yap-6.3/packages/chr/chr_translate.chr

/*  $Id$

    Part of CHR (Constraint Handling Rules)

    Author:        Tom Schrijvers
    E-mail:        Tom.Schrijvers@cs.kuleuven.be
    WWW:           http://www.swi-prolog.org
    Copyright (C): 2003-2004, K.U. Leuven

    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
    as published by the Free Software Foundation; either version 2
    of the License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

    As a special exception, if you link this library with other files,
    compiled with a Free Software compiler, to produce an executable, this
    library does not by itself cause the resulting executable to be covered
    by the GNU General Public License. This exception does not however
    invalidate any other reasons why the executable file might be covered by
    the GNU General Public License.
*/

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%%   ____ _   _ ____     ____                      _ _
%%  / ___| | | |  _ \   / ___|___  _ __ ___  _ __ (_) | ___ _ __
%% | |   | |_| | |_) | | |   / _ \| '_ ` _ \| '_ \| | |/ _ \ '__|
%% | |___|  _  |  _ <  | |__| (_) | | | | | | |_) | | |  __/ |
%%  \____|_| |_|_| \_\  \____\___/|_| |_| |_| .__/|_|_|\___|_|
%%                                          |_|
%%
%% hProlog CHR compiler:
%%
%%	* by Tom Schrijvers, K.U. Leuven, Tom.Schrijvers@cs.kuleuven.be
%%
%%	* based on the SICStus CHR compilation by Christian Holzbaur
%%
%% First working version: 6 June 2003
%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%% TODO {{{
%%
%% URGENTLY TODO
%%
%%	* add mode checking to debug mode
%%	* add groundness info to a.i.-based observation analysis
%%	* proper fd/index analysis
%%	* re-add generation checking
%%	* untangle CHR-level and target source-level generation & optimization
%%
%% AGGRESSIVE OPTIMISATION IDEAS
%%
%%	* analyze history usage to determine whether/when
%%	  cheaper suspension is possible:
%%		don't use history when all partners are passive and self never triggers
%%	* store constraint unconditionally for unconditional propagation rule,
%%	  if first, i.e. without checking history and set trigger cont to next occ
%%	* get rid of suspension passing for never triggered constraints,
%%	   up to allocation occurrence
%%	* get rid of call indirection for never triggered constraints
%%	  up to first allocation occurrence.
%%	* get rid of unnecessary indirection if last active occurrence
%%	  before unconditional removal is head2, e.g.
%%		a \ b <=> true.
%%		a <=> true.
%%	* Eliminate last clause of never stored constraint, if its body
%%	  is fail, e.g.
%%		a ...
%%		a <=> fail.
%%	* Specialize lookup operations and indexes for functional dependencies.
%%
%% MORE TODO
%%
%%	* map A \ B <=> true | true rules
%%	  onto efficient code that empties the constraint stores of B
%%	  in O(1) time for ground constraints where A and B do not share
%%	  any variables
%%	* ground matching seems to be not optimized for compound terms
%%	  in case of simpagation_head2 and propagation occurrences
%%	* analysis for storage delaying (see primes for case)
%%	* internal constraints declaration + analyses?
%%	* Do not store in global variable store if not necessary
%%		NOTE: affects show_store/1
%%	* var_assoc multi-level store: variable - ground
%%	* Do not maintain/check unnecessary propagation history
%%		for reasons of anti-monotony
%%	* Strengthen storage analysis for propagation rules
%%		reason about bodies of rules only containing constraints
%%		-> fixpoint with observation analysis
%%	* instantiation declarations
%%		COMPOUND (bound to nonvar)
%%			avoid nonvar tests
%%
%%	* make difference between cheap guards		for reordering
%%	                      and non-binding guards	for lock removal
%%	* fd -> once/[] transformation for propagation
%%	* cheap guards interleaved with head retrieval + faster
%%	  via-retrieval + non-empty checking for propagation rules
%%	  redo for simpagation_head2 prelude
%%	* intelligent backtracking for simplification/simpagation rule
%%		generator_1(X),'_$savecp'(CP_1),
%%              ...
%%              if( (
%%			generator_n(Y),
%%			test(X,Y)
%%		    ),
%%		    true,
%%		    ('_$cutto'(CP_1), fail)
%%		),
%%		...
%%
%%	  or recently developped cascading-supported approach
%%      * intelligent backtracking for propagation rule
%%          use additional boolean argument for each possible smart backtracking
%%          when boolean at end of list true  -> no smart backtracking
%%                                      false -> smart backtracking
%%          only works for rules with at least 3 constraints in the head
%%	* (set semantics + functional dependency) declaration + resolution
%% }}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
:- module(chr_translate,
	  [ chr_translate/2		% +Decls, -TranslatedDecls
	  , chr_translate_line_info/3	% +DeclsWithLines, -TranslatedDecls
	  ]).
%% SWI begin {{{
:- use_module(library(lists),[member/2, append/3,reverse/2,permutation/2,last/2]).
:- use_module(library(ordsets)).
:- use_module(library(aggregate)).
:- use_module(library(apply_macros)).
:- use_module(library(occurs)).
:- use_module(library(assoc)).
:- use_module(library(dialect/hprolog)).
%% SWI end }}}

% imports and operators {{{
:- use_module(pairlist).
:- use_module(a_star).
:- use_module(listmap).
:- use_module(clean_code).
:- use_module(builtins).
:- use_module(find).
:- use_module(binomialheap).
:- use_module(guard_entailment).
:- use_module(chr_compiler_options).
:- use_module(chr_compiler_utility).
:- use_module(chr_compiler_errors).
:- include(chr_op).
:- op(1150, fx, chr_type).
:- op(1150, fx, chr_declaration).
:- op(1130, xfx, --->).
:- op(980, fx, (+)).
:- op(980, fx, (-)).
:- op(980, fx, (?)).
:- op(1150, fx, constraints).
:- op(1150, fx, chr_constraint).
% }}}

:- chr_option(debug,off).
:- chr_option(optimize,full).
:- chr_option(check_guard_bindings,off).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Type Declarations {{{
:- chr_type list(T)	---> [] ; [T|list(T)].

:- chr_type list	==   list(any).

:- chr_type mode	---> (+) ; (-) ; (?).

:- chr_type maybe(T)	---> yes(T) ; no.

:- chr_type constraint	---> any / any.

:- chr_type module_name == any.

:- chr_type pragma_rule --->	pragma(rule,idspair,list(pragma_type),maybe(rule_name),rule_nb).
:- chr_type rule	--->	rule(list(any),list(any),goal,goal).
:- chr_type idspair	--->	ids(list(id),list(id)).

:- chr_type pragma_type	--->	passive(id)
			;	mpassive(list(id))
			;	already_in_heads
			;	already_in_heads(id)
			;	no_history
			;	history(history_name,list(id)).
:- chr_type history_name==	any.

:- chr_type rule_name	==	any.
:- chr_type rule_nb	==	natural.
:- chr_type id		==	natural.
:- chr_type occurrence  ==	int.

:- chr_type goal	==	any.

:- chr_type store_type	--->	default
			;	multi_store(list(store_type))
			;	multi_hash(list(list(int)))
			;	multi_inthash(list(list(int)))
			;	global_singleton
			;	global_ground
			%	EXPERIMENTAL STORES
			;	atomic_constants(list(int),list(any),coverage)
			;	ground_constants(list(int),list(any),coverage)
			;	var_assoc_store(int,list(int))
			;	identifier_store(int)
			;	type_indexed_identifier_store(int,any).
:- chr_type coverage	--->	complete ; incomplete.
% }}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%------------------------------------------------------------------------------%
:- chr_constraint chr_source_file/1.
:- chr_option(mode,chr_source_file(+)).
:- chr_option(type_declaration,chr_source_file(module_name)).
%------------------------------------------------------------------------------%
chr_source_file(_) \ chr_source_file(_) <=> true.

%------------------------------------------------------------------------------%
:- chr_constraint get_chr_source_file/1.
:- chr_option(mode,get_chr_source_file(-)).
:- chr_option(type_declaration,get_chr_source_file(module_name)).
%------------------------------------------------------------------------------%
chr_source_file(Mod) \ get_chr_source_file(Query)
	<=> Query = Mod .
get_chr_source_file(Query)
	<=> Query = user.


%------------------------------------------------------------------------------%
:- chr_constraint target_module/1.
:- chr_option(mode,target_module(+)).
:- chr_option(type_declaration,target_module(module_name)).
%------------------------------------------------------------------------------%
target_module(_) \ target_module(_) <=> true.

%------------------------------------------------------------------------------%
:- chr_constraint get_target_module/1.
:- chr_option(mode,get_target_module(-)).
:- chr_option(type_declaration,get_target_module(module_name)).
%------------------------------------------------------------------------------%
target_module(Mod) \ get_target_module(Query)
	<=> Query = Mod .
get_target_module(Query)
	<=> Query = user.

%------------------------------------------------------------------------------%
:- chr_constraint line_number/2.
:- chr_option(mode,line_number(+,+)).
:- chr_option(type_declaration,line_number(rule_nb,int)).
%------------------------------------------------------------------------------%
line_number(RuleNb,LineNb) \ line_number(RuleNb,LineNumber) <=> true.

%------------------------------------------------------------------------------%
:- chr_constraint get_line_number/2.
:- chr_option(mode,get_line_number(+,-)).
:- chr_option(type_declaration,get_line_number(rule_nb,int)).
%------------------------------------------------------------------------------%
line_number(RuleNb,LineNb) \ get_line_number(RuleNb,Q) <=> Q = LineNb.
get_line_number(RuleNb,Q) <=> Q = 0.			% no line number available

:- chr_constraint indexed_argument/2.			% argument instantiation may enable applicability of rule
:- chr_option(mode,indexed_argument(+,+)).
:- chr_option(type_declaration,indexed_argument(constraint,int)).

:- chr_constraint is_indexed_argument/2.
:- chr_option(mode,is_indexed_argument(+,+)).
:- chr_option(type_declaration,is_indexed_argument(constraint,int)).

:- chr_constraint constraint_mode/2.
:- chr_option(mode,constraint_mode(+,+)).
:- chr_option(type_declaration,constraint_mode(constraint,list(mode))).

:- chr_constraint get_constraint_mode/2.
:- chr_option(mode,get_constraint_mode(+,-)).
:- chr_option(type_declaration,get_constraint_mode(constraint,list(mode))).

:- chr_constraint may_trigger/1.
:- chr_option(mode,may_trigger(+)).
:- chr_option(type_declaration,may_trigger(constraint)).

:- chr_constraint only_ground_indexed_arguments/1.
:- chr_option(mode,only_ground_indexed_arguments(+)).
:- chr_option(type_declaration,only_ground_indexed_arguments(constraint)).

:- chr_constraint none_suspended_on_variables/0.

:- chr_constraint are_none_suspended_on_variables/0.

:- chr_constraint store_type/2.
:- chr_option(mode,store_type(+,+)).
:- chr_option(type_declaration,store_type(constraint,store_type)).

:- chr_constraint get_store_type/2.
:- chr_option(mode,get_store_type(+,?)).
:- chr_option(type_declaration,get_store_type(constraint,store_type)).

:- chr_constraint update_store_type/2.
:- chr_option(mode,update_store_type(+,+)).
:- chr_option(type_declaration,update_store_type(constraint,store_type)).

:- chr_constraint actual_store_types/2.
:- chr_option(mode,actual_store_types(+,+)).
:- chr_option(type_declaration,actual_store_types(constraint,list(store_type))).

:- chr_constraint assumed_store_type/2.
:- chr_option(mode,assumed_store_type(+,+)).
:- chr_option(type_declaration,assumed_store_type(constraint,store_type)).

:- chr_constraint validate_store_type_assumption/1.
:- chr_option(mode,validate_store_type_assumption(+)).
:- chr_option(type_declaration,validate_store_type_assumption(constraint)).

:- chr_constraint rule_count/1.
:- chr_option(mode,rule_count(+)).
:- chr_option(type_declaration,rule_count(natural)).

:- chr_constraint inc_rule_count/1.
:- chr_option(mode,inc_rule_count(-)).
:- chr_option(type_declaration,inc_rule_count(natural)).

rule_count(_) \ rule_count(_)
	<=> true.
rule_count(C), inc_rule_count(NC)
	<=> NC is C + 1, rule_count(NC).
inc_rule_count(NC)
	<=> NC = 1, rule_count(NC).

:- chr_constraint passive/2.
:- chr_option(mode,passive(+,+)).
:- chr_option(type_declaration,passive(rule_nb,id)).

:- chr_constraint is_passive/2.
:- chr_option(mode,is_passive(+,+)).
:- chr_option(type_declaration,is_passive(rule_nb,id)).

:- chr_constraint any_passive_head/1.
:- chr_option(mode,any_passive_head(+)).

:- chr_constraint new_occurrence/4.
:- chr_option(mode,new_occurrence(+,+,+,+)).

:- chr_constraint occurrence/5.
:- chr_option(mode,occurrence(+,+,+,+,+)).

:- chr_type occurrence_type ---> simplification ; propagation.
:- chr_option(type_declaration,occurrence(constraint,occurrence,rule_nb,id,occurrence_type)).

:- chr_constraint get_occurrence/4.
:- chr_option(mode,get_occurrence(+,+,-,-)).

:- chr_constraint get_occurrence/5.
:- chr_option(mode,get_occurrence(+,+,-,-,-)).

:- chr_constraint get_occurrence_from_id/4.
:- chr_option(mode,get_occurrence_from_id(+,-,+,+)).

:- chr_constraint max_occurrence/2.
:- chr_option(mode,max_occurrence(+,+)).

:- chr_constraint get_max_occurrence/2.
:- chr_option(mode,get_max_occurrence(+,-)).

:- chr_constraint allocation_occurrence/2.
:- chr_option(mode,allocation_occurrence(+,+)).

:- chr_constraint get_allocation_occurrence/2.
:- chr_option(mode,get_allocation_occurrence(+,-)).

:- chr_constraint rule/2.
:- chr_option(mode,rule(+,+)).
:- chr_option(type_declaration,rule(rule_nb,pragma_rule)).

:- chr_constraint get_rule/2.
:- chr_option(mode,get_rule(+,-)).
:- chr_option(type_declaration,get_rule(int,pragma_rule)).

:- chr_constraint least_occurrence/2.
:- chr_option(mode,least_occurrence(+,+)).
:- chr_option(type_declaration,least_occurrence(any,list)).

:- chr_constraint is_least_occurrence/1.
:- chr_option(mode,is_least_occurrence(+)).


indexed_argument(FA,I) \ indexed_argument(FA,I) <=> true.
indexed_argument(FA,I) \ is_indexed_argument(FA,I) <=> true.
is_indexed_argument(_,_) <=> fail.

%%% C O N S T R A I N T   M O D E %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

constraint_mode(FA,_) \ constraint_mode(FA,_) <=> true.
constraint_mode(FA,Mode) \ get_constraint_mode(FA,Q) <=>
	Q = Mode.
get_constraint_mode(FA,Q) <=>
	FA = _ / N,
	replicate(N,(?),Q).

%%% M A Y   T R I G G E R %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

may_trigger(FA) <=> \+ has_active_occurrence(FA) | fail.
constraint_mode(FA,Mode), indexed_argument(FA,I) \ may_trigger(FA) <=>
  nth1(I,Mode,M),
  M \== (+) |
  is_stored(FA).
may_trigger(FA) <=> chr_pp_flag(debugable,on).	% in debug mode, we assume everything can be triggered

constraint_mode(FA,Mode), indexed_argument(FA,I) \ only_ground_indexed_arguments(FA)
	<=>
		nth1(I,Mode,M),
		M \== (+)
	|
		fail.
only_ground_indexed_arguments(_) <=>
	true.

none_suspended_on_variables \ none_suspended_on_variables <=> true.
none_suspended_on_variables \ are_none_suspended_on_variables <=> true.
are_none_suspended_on_variables <=> fail.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% STORE TYPES
%
% The functionality for inspecting and deciding on the different types of constraint
% store / indexes for constraints.

store_type(FA,StoreType)
	==> chr_pp_flag(verbose,on)
	|
	format('The indexes for ~w are:\n',[FA]),
	format_storetype(StoreType).
	% chr_info(verbose,'Storetype of ~w is ~w.\n',[FA,StoreType]).

format_storetype(multi_store(StoreTypes)) :- !,
	maplist(format_storetype,StoreTypes).
format_storetype(atomic_constants(Index,Constants,_)) :-
	format('\t* a trie index on the argument(s) ~w for the ground terms ~w\n',[Index,Constants]).
format_storetype(ground_constants(Index,Constants,_)) :-
	format('\t* a trie index on the argument(s) ~w for the ground terms ~w\n',[Index,Constants]).
format_storetype(StoreType) :-
	format('\t* ~w\n',[StoreType]).


% 1. Inspection
% ~~~~~~~~~~~~~
%
%

get_store_type_normal @
store_type(FA,Store) \ get_store_type(FA,Query)
	<=> Query = Store.

get_store_type_assumed @
assumed_store_type(FA,Store) \ get_store_type(FA,Query)
	<=> Query = Store.

get_store_type_default @
get_store_type(_,Query)
	<=> Query = default.

% 2. Store type registration
% ~~~~~~~~~~~~~~~~~~~~~~~~~~

actual_store_types(C,STs) \ update_store_type(C,ST)
	<=> memberchk(ST,STs) | true.
update_store_type(C,ST), actual_store_types(C,STs)
	<=>
		actual_store_types(C,[ST|STs]).
update_store_type(C,ST)
	<=>
		actual_store_types(C,[ST]).

% 3. Final decision on store types
% ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

validate_store_type_assumption(C) \ actual_store_types(C,STs), actual_atomic_multi_hash_keys(C,Index,Keys)
	<=>
		true % chr_pp_flag(experiment,on)
	|
		selectchk(multi_hash([Index]),STs,STs0),
		Index = [IndexPos],
		( get_constraint_arg_type(C,IndexPos,Type),
		  enumerated_atomic_type(Type,Atoms) ->
			/* use the type constants rather than the collected keys */
			Constants    = Atoms,
			Completeness = complete
		;
			Constants    = Keys,
			Completeness = incomplete
		),
		actual_store_types(C,[atomic_constants(Index,Constants,Completeness)|STs0]).
validate_store_type_assumption(C) \ actual_store_types(C,STs), actual_ground_multi_hash_keys(C,Index,Constants0)
	<=>
		true % chr_pp_flag(experiment,on)
	|
		( Index = [IndexPos],
                  get_constraint_arg_type(C,IndexPos,Type),
		  Type = chr_enum(Constants)
		->
			Completeness = complete
		;
			Constants    = Constants0,
			Completeness = incomplete
		),
		selectchk(multi_hash([Index]),STs,STs0),
		actual_store_types(C,[ground_constants(Index,Constants,Completeness)|STs0]).

get_constraint_arg_type(C,Pos,Type) :-
                  get_constraint_type(C,Types),
		  nth1(Pos,Types,Type0),
		  unalias_type(Type0,Type).

validate_store_type_assumption(C) \ actual_store_types(C,STs)
	<=>
		% chr_pp_flag(experiment,on),
		memberchk(multi_hash([[Index]]),STs),
		get_constraint_type(C,Types),
		nth1(Index,Types,Type),
		enumerated_atomic_type(Type,Atoms)
	|
		selectchk(multi_hash([[Index]]),STs,STs0),
		actual_store_types(C,[atomic_constants([Index],Atoms,complete)|STs0]).
validate_store_type_assumption(C) \ actual_store_types(C,STs)
	<=>
		memberchk(multi_hash([[Index]]),STs),
		get_constraint_arg_type(C,Index,Type),
		Type = chr_enum(Constants)
	|
		selectchk(multi_hash([[Index]]),STs,STs0),
		actual_store_types(C,[ground_constants([Index],Constants,complete)|STs0]).
validate_store_type_assumption(C), actual_store_types(C,STs), assumed_store_type(C,_)	% automatic assumption
	<=>
		( /* chr_pp_flag(experiment,on), */ maplist(partial_store,STs) ->
			Stores = [global_ground|STs]
		;
			Stores = STs
		),
		store_type(C,multi_store(Stores)).
validate_store_type_assumption(C), actual_store_types(C,STs), store_type(C,_)		% user assumption
	<=>
		store_type(C,multi_store(STs)).
validate_store_type_assumption(C), assumed_store_type(C,_)				% no lookups on constraint in debug mode
	<=>
		chr_pp_flag(debugable,on)
	|
		store_type(C,default).
validate_store_type_assumption(C), assumed_store_type(C,_)				% no lookups on constraint
	<=> store_type(C,global_ground).
validate_store_type_assumption(C)
	<=> true.

partial_store(ground_constants(_,_,incomplete)).
partial_store(atomic_constants(_,_,incomplete)).

%%% P A S S I V E %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
passive(R,ID) \ passive(R,ID) <=> true.

passive(RuleNb,ID) \ is_passive(RuleNb,ID) <=> true.
is_passive(_,_) <=> fail.

passive(RuleNb,_) \ any_passive_head(RuleNb)
	<=> true.
any_passive_head(_)
	<=> fail.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

max_occurrence(C,N) \ max_occurrence(C,M)
	<=> N >= M | true.

max_occurrence(C,MO), new_occurrence(C,RuleNb,ID,Type) <=>
	NO is MO + 1,
	occurrence(C,NO,RuleNb,ID,Type),
	max_occurrence(C,NO).
new_occurrence(C,RuleNb,ID,_) <=>
	chr_error(internal,'new_occurrence: missing max_occurrence for ~w in rule ~w\n',[C,RuleNb]).

max_occurrence(C,MON) \ get_max_occurrence(C,Q)
	<=> Q = MON.
get_max_occurrence(C,Q)
	<=> chr_error(internal,'get_max_occurrence: missing max occurrence for ~w\n',[C]).

occurrence(C,ON,Rule,ID,_) \ get_occurrence(C,ON,QRule,QID)
	<=> Rule = QRule, ID = QID.
get_occurrence(C,O,_,_)
	<=> chr_error(internal,'get_occurrence: missing occurrence ~w:~w\n',[C,O]).

occurrence(C,ON,Rule,ID,OccType) \ get_occurrence(C,ON,QRule,QID,QOccType)
	<=> Rule = QRule, ID = QID, OccType = QOccType.
get_occurrence(C,O,_,_,_)
	<=> chr_error(internal,'get_occurrence: missing occurrence ~w:~w\n',[C,O]).

occurrence(C,ON,Rule,ID,_) \ get_occurrence_from_id(QC,QON,Rule,ID)
	<=> QC = C, QON = ON.
get_occurrence_from_id(C,O,_,_)
	<=> chr_error(internal,'get_occurrence_from_id: missing occurrence ~w:~w\n',[]).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Late allocation

late_allocation_analysis(Cs) :-
	( chr_pp_flag(late_allocation,on) ->
		maplist(late_allocation, Cs)
	;
		true
	).

late_allocation(C) :- late_allocation(C,0).
late_allocation(C,O) :- allocation_occurrence(C,O), !.
late_allocation(C,O) :- NO is O + 1, late_allocation(C,NO).

% A L L O C C A T I O N   O C C U R R E N C E %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

allocation_occurrence(C,0) ==> stored_in_guard_before_next_kept_occurrence(C,0).

rule(RuleNb,Rule), occurrence(C,O,RuleNb,Id,Type), allocation_occurrence(C,O) ==>
	\+ is_passive(RuleNb,Id),
	Type == propagation,
	( stored_in_guard_before_next_kept_occurrence(C,O) ->
		true
	; Rule = pragma(rule([_|_],_,_,_),_,_,_,_) ->	% simpagation rule
		is_observed(C,O)
	; is_least_occurrence(RuleNb) ->		% propagation rule
		is_observed(C,O)
	;
		true
	).

stored_in_guard_before_next_kept_occurrence(C,O) :-
	chr_pp_flag(store_in_guards, on),
	NO is O + 1,
	stored_in_guard_lookahead(C,NO).

:- chr_constraint stored_in_guard_lookahead/2.
:- chr_option(mode, stored_in_guard_lookahead(+,+)).

occurrence(C,O,RuleNb,Id,_), passive(RuleNb,Id) \ stored_in_guard_lookahead(C,O) <=>
	NO is O + 1, stored_in_guard_lookahead(C,NO).
occurrence(C,O,RuleNb,Id,Type) \ stored_in_guard_lookahead(C,O) <=>
	Type == simplification,
	( is_stored_in_guard(C,RuleNb) ->
		true
	;
		NO is O + 1, stored_in_guard_lookahead(C,NO)
	).
stored_in_guard_lookahead(_,_) <=> fail.


rule(RuleNb,Rule), occurrence(C,O,RuleNb,ID,_), allocation_occurrence(C,AO)
	\ least_occurrence(RuleNb,[ID|IDs])
	<=> AO >= O, \+ may_trigger(C) |
	least_occurrence(RuleNb,IDs).
rule(RuleNb,Rule), passive(RuleNb,ID)
	\ least_occurrence(RuleNb,[ID|IDs])
	<=> least_occurrence(RuleNb,IDs).

rule(RuleNb,Rule)
	==> Rule = pragma(rule([],_,_,_),ids([],IDs),_,_,_) |
	least_occurrence(RuleNb,IDs).

least_occurrence(RuleNb,[]) \ is_least_occurrence(RuleNb)
	<=> true.
is_least_occurrence(_)
	<=> fail.

allocation_occurrence(C,O) \ get_allocation_occurrence(C,Q)
	<=> Q = O.
get_allocation_occurrence(_,Q)
	<=> chr_pp_flag(late_allocation,off), Q=0.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

rule(RuleNb,Rule) \ get_rule(RuleNb,Q)
	<=> Q = Rule.
get_rule(_,_)
	<=> fail.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%% C O N S T R A I N T   I N D E X %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% Default store constraint index assignment.

:- chr_constraint constraint_index/2.			% constraint_index(F/A,DefaultStoreAndAttachedIndex)
:- chr_option(mode,constraint_index(+,+)).
:- chr_option(type_declaration,constraint_index(constraint,int)).

:- chr_constraint get_constraint_index/2.
:- chr_option(mode,get_constraint_index(+,-)).
:- chr_option(type_declaration,get_constraint_index(constraint,int)).

:- chr_constraint get_indexed_constraint/2.
:- chr_option(mode,get_indexed_constraint(+,-)).
:- chr_option(type_declaration,get_indexed_constraint(int,constraint)).

:- chr_constraint max_constraint_index/1.			% max_constraint_index(MaxDefaultStoreAndAttachedIndex)
:- chr_option(mode,max_constraint_index(+)).
:- chr_option(type_declaration,max_constraint_index(int)).

:- chr_constraint get_max_constraint_index/1.
:- chr_option(mode,get_max_constraint_index(-)).
:- chr_option(type_declaration,get_max_constraint_index(int)).

constraint_index(C,Index) \ get_constraint_index(C,Query)
	<=> Query = Index.
get_constraint_index(C,Query)
	<=> fail.

constraint_index(C,Index) \ get_indexed_constraint(Index,Q)
	<=> Q = C.
get_indexed_constraint(Index,Q)
	<=> fail.

max_constraint_index(Index) \ get_max_constraint_index(Query)
	<=> Query = Index.
get_max_constraint_index(Query)
	<=> Query = 0.

set_constraint_indices(Constraints) :-
	set_constraint_indices(Constraints,1).
set_constraint_indices([],M) :-
	N is M - 1,
	max_constraint_index(N).
set_constraint_indices([C|Cs],N) :-
	( ( chr_pp_flag(debugable, on) ; \+ only_ground_indexed_arguments(C), is_stored(C) ;  is_stored(C), get_store_type(C,default)
	  ; get_store_type(C,var_assoc_store(_,_))) ->
		constraint_index(C,N),
		M is N + 1,
		set_constraint_indices(Cs,M)
	;
		set_constraint_indices(Cs,N)
	).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Identifier Indexes

:- chr_constraint identifier_size/1.
:- chr_option(mode,identifier_size(+)).
:- chr_option(type_declaration,identifier_size(natural)).

identifier_size(_) \ identifier_size(_)
	<=>
		true.

:- chr_constraint get_identifier_size/1.
:- chr_option(mode,get_identifier_size(-)).
:- chr_option(type_declaration,get_identifier_size(natural)).

identifier_size(Size) \ get_identifier_size(Q)
	<=>
		Q = Size.

get_identifier_size(Q)
	<=>
		Q = 1.

:- chr_constraint identifier_index/3.
:- chr_option(mode,identifier_index(+,+,+)).
:- chr_option(type_declaration,identifier_index(constraint,natural,natural)).

identifier_index(C,I,_) \ identifier_index(C,I,_)
	<=>
		true.

:- chr_constraint get_identifier_index/3.
:- chr_option(mode,get_identifier_index(+,+,-)).
:- chr_option(type_declaration,get_identifier_index(constraint,natural,natural)).

identifier_index(C,I,II) \ get_identifier_index(C,I,Q)
	<=>
		Q = II.
identifier_size(Size), get_identifier_index(C,I,Q)
	<=>
		NSize is Size + 1,
		identifier_index(C,I,NSize),
		identifier_size(NSize),
		Q = NSize.
get_identifier_index(C,I,Q)
	<=>
		identifier_index(C,I,2),
		identifier_size(2),
		Q = 2.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Type Indexed Identifier Indexes

:- chr_constraint type_indexed_identifier_size/2.
:- chr_option(mode,type_indexed_identifier_size(+,+)).
:- chr_option(type_declaration,type_indexed_identifier_size(any,natural)).

type_indexed_identifier_size(IndexType,_) \ type_indexed_identifier_size(IndexType,_)
	<=>
		true.

:- chr_constraint get_type_indexed_identifier_size/2.
:- chr_option(mode,get_type_indexed_identifier_size(+,-)).
:- chr_option(type_declaration,get_type_indexed_identifier_size(any,natural)).

type_indexed_identifier_size(IndexType,Size) \ get_type_indexed_identifier_size(IndexType,Q)
	<=>
		Q = Size.

get_type_indexed_identifier_size(IndexType,Q)
	<=>
		Q = 1.

:- chr_constraint type_indexed_identifier_index/4.
:- chr_option(mode,type_indexed_identifier_index(+,+,+,+)).
:- chr_option(type_declaration,type_indexed_identifier_index(any,constraint,natural,natural)).

type_indexed_identifier_index(_,C,I,_) \ type_indexed_identifier_index(_,C,I,_)
	<=>
		true.

:- chr_constraint get_type_indexed_identifier_index/4.
:- chr_option(mode,get_type_indexed_identifier_index(+,+,+,-)).
:- chr_option(type_declaration,get_type_indexed_identifier_index(any,constraint,natural,natural)).

type_indexed_identifier_index(IndexType,C,I,II) \ get_type_indexed_identifier_index(IndexType,C,I,Q)
	<=>
		Q = II.
type_indexed_identifier_size(IndexType,Size), get_type_indexed_identifier_index(IndexType,C,I,Q)
	<=>
		NSize is Size + 1,
		type_indexed_identifier_index(IndexType,C,I,NSize),
		type_indexed_identifier_size(IndexType,NSize),
		Q = NSize.
get_type_indexed_identifier_index(IndexType,C,I,Q)
	<=>
		type_indexed_identifier_index(IndexType,C,I,2),
		type_indexed_identifier_size(IndexType,2),
		Q = 2.

type_indexed_identifier_structure(IndexType,Structure) :-
	type_indexed_identifier_name(IndexType,type_indexed_identifier_struct,Functor),
	get_type_indexed_identifier_size(IndexType,Arity),
	functor(Structure,Functor,Arity).
type_indexed_identifier_name(IndexType,Prefix,Name) :-
	( atom(IndexType) ->
		IndexTypeName = IndexType
	;
		term_to_atom(IndexType,IndexTypeName)
	),
	atom_concat_list([Prefix,'_',IndexTypeName],Name).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%




%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%% Translation

chr_translate(Declarations,NewDeclarations) :-
	chr_translate_line_info(Declarations,'bootstrap',NewDeclarations).

chr_translate_line_info(Declarations0,File,NewDeclarations) :-
	chr_banner,
	restart_after_flattening(Declarations0,Declarations),
	init_chr_pp_flags,
	chr_source_file(File),
	/* sort out the interesting stuff from the input */
	partition_clauses(Declarations,Constraints0,Rules0,OtherClauses),
	chr_compiler_options:sanity_check,

	dump_code(Declarations),

	check_declared_constraints(Constraints0),
	generate_show_constraint(Constraints0,Constraints,Rules0,Rules1),
	add_constraints(Constraints),
	add_rules(Rules1),
	generate_never_stored_rules(Constraints,NewRules),
	add_rules(NewRules),
	append(Rules1,NewRules,Rules),
	chr_analysis(Rules,Constraints,Declarations),
	time('constraint code generation',chr_translate:constraints_code(Constraints,ConstraintClauses)),
	time('validate store assumptions',chr_translate:validate_store_type_assumptions(Constraints)),
	phase_end(validate_store_type_assumptions),
	used_states_known,
	time('store code generation',chr_translate:store_management_preds(Constraints,StoreClauses)),	% depends on actual code used
	insert_declarations(OtherClauses, Clauses0),
	chr_module_declaration(CHRModuleDeclaration),
	append([StoreClauses,ConstraintClauses,CHRModuleDeclaration,[end_of_file]],StuffyGeneratedClauses),
	clean_clauses(StuffyGeneratedClauses,GeneratedClauses),
	append([Clauses0,GeneratedClauses], NewDeclarations),
	dump_code(NewDeclarations),
	!. /* cut choicepoint of restart_after_flattening */

chr_analysis(Rules,Constraints,Declarations) :-
	maplist(pragma_rule_to_ast_rule,Rules,AstRules),
	check_rules(Rules,AstRules,Constraints),
	time('type checking',chr_translate:static_type_check(Rules,AstRules)),
	/* constants */
	collect_constants(Rules,AstRules,Constraints,Declarations),
	add_occurrences(Rules,AstRules),
	time('functional dependency',chr_translate:functional_dependency_analysis(Rules)),
	time('set semantics',chr_translate:set_semantics_rules(Rules)),
	time('symmetry analysis',chr_translate:symmetry_analysis(Rules)),
	time('guard simplification',chr_translate:guard_simplification),
	time('late storage',chr_translate:storage_analysis(Constraints)),
	time('observation',chr_translate:observation_analysis(Constraints)),
	time('ai observation',chr_translate:ai_observation_analysis(Constraints)),
	time('late allocation',chr_translate:late_allocation_analysis(Constraints)),
	partial_wake_analysis,
	time('assume constraint stores',chr_translate:assume_constraint_stores(Constraints)),
	time('default constraint indices',chr_translate:set_constraint_indices(Constraints)),
	time('check storedness assertions',chr_translate:check_storedness_assertions(Constraints)),
	time('continuation analysis',chr_translate:continuation_analysis(Constraints)).

store_management_preds(Constraints,Clauses) :-
	generate_attach_detach_a_constraint_all(Constraints,AttachAConstraintClauses),
	generate_attr_unify_hook(AttrUnifyHookClauses),
	generate_attach_increment(AttachIncrementClauses),
	generate_extra_clauses(Constraints,ExtraClauses),
	generate_insert_delete_constraints(Constraints,DeleteClauses),
	generate_attach_code(Constraints,StoreClauses),
	generate_counter_code(CounterClauses),
	generate_dynamic_type_check_clauses(TypeCheckClauses),
	append([AttachAConstraintClauses
	       ,AttachIncrementClauses
	       ,AttrUnifyHookClauses
	       ,ExtraClauses
	       ,DeleteClauses
	       ,StoreClauses
	       ,CounterClauses
	       ,TypeCheckClauses
	       ]
	      ,Clauses).


insert_declarations(Clauses0, Clauses) :-
	findall((:- use_module(chr(Module))),(auxiliary_module(Module), is_used_auxiliary_module(Module)),Decls),
	append(Clauses0, [(:- use_module(chr(chr_runtime)))|Decls], Clauses).

auxiliary_module(chr_hashtable_store).
auxiliary_module(chr_integertable_store).
auxiliary_module(chr_assoc_store).

generate_counter_code(Clauses) :-
	( chr_pp_flag(store_counter,on) ->
		Clauses = [
			('$counter_init'(N1) :- nb_setval(N1,0)) ,
			('$counter'(N2,X1) :- nb_getval(N2,X1)),
			('$counter_inc'(N) :- nb_getval(N,X), Y is X + 1, nb_setval(N,Y)),
			(:- '$counter_init'('$insert_counter')),
			(:- '$counter_init'('$delete_counter')),
			('$insert_counter_inc' :- '$counter_inc'('$insert_counter')),
			('$delete_counter_inc' :- '$counter_inc'('$delete_counter')),
			( counter_stats(I,D) :- '$counter'('$insert_counter',I),'$counter'('$delete_counter',D))
		]
	;
		Clauses = []
	).

% for systems with multifile declaration
chr_module_declaration(CHRModuleDeclaration) :-
	get_target_module(Mod),
	( Mod \== chr_translate, chr_pp_flag(toplevel_show_store,on) ->
		CHRModuleDeclaration = [
			(:- multifile chr:'$chr_module'/1),
			chr:'$chr_module'(Mod)
		]
	;
		CHRModuleDeclaration = []
	).


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%% Partitioning of clauses into constraint declarations, chr rules and other
%% clauses

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	partition_clauses(+Clauses,-ConstraintDeclarations,-Rules,-OtherClauses) is det.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
partition_clauses([],[],[],[]).
partition_clauses([Clause|Clauses],ConstraintDeclarations,Rules,OtherClauses) :-
	( parse_rule(Clause,Rule) ->
		ConstraintDeclarations = RestConstraintDeclarations,
		Rules = [Rule|RestRules],
		OtherClauses = RestOtherClauses
	; is_declaration(Clause,ConstraintDeclaration) ->
		append(ConstraintDeclaration,RestConstraintDeclarations,ConstraintDeclarations),
		Rules = RestRules,
		OtherClauses = RestOtherClauses
	; is_module_declaration(Clause,Mod) ->
		target_module(Mod),
		ConstraintDeclarations = RestConstraintDeclarations,
		Rules = RestRules,
		OtherClauses = [Clause|RestOtherClauses]
	; is_type_definition(Clause) ->
		ConstraintDeclarations = RestConstraintDeclarations,
		Rules = RestRules,
		OtherClauses = RestOtherClauses
	; is_chr_declaration(Clause) ->
		ConstraintDeclarations = RestConstraintDeclarations,
		Rules = RestRules,
		OtherClauses = RestOtherClauses
	; Clause = (handler _) ->
		chr_warning(deprecated(Clause),'Backward compatibility: ignoring handler/1 declaration.\n',[]),
		ConstraintDeclarations = RestConstraintDeclarations,
		Rules = RestRules,
		OtherClauses = RestOtherClauses
	; Clause = (rules _) ->
		chr_warning(deprecated(Clause),'Backward compatibility: ignoring rules/1 declaration.\n',[]),
		ConstraintDeclarations = RestConstraintDeclarations,
		Rules = RestRules,
		OtherClauses = RestOtherClauses
	; Clause = option(OptionName,OptionValue) ->
		chr_warning(deprecated(Clause),'Instead use `:-chr_option(~w,~w).\'\n',[OptionName,OptionValue]),
		handle_option(OptionName,OptionValue),
		ConstraintDeclarations = RestConstraintDeclarations,
		Rules = RestRules,
		OtherClauses = RestOtherClauses
	; Clause = (:-chr_option(OptionName,OptionValue)) ->
		handle_option(OptionName,OptionValue),
		ConstraintDeclarations = RestConstraintDeclarations,
		Rules = RestRules,
		OtherClauses = RestOtherClauses
	; Clause = ('$chr_compiled_with_version'(_)) ->
		ConstraintDeclarations = RestConstraintDeclarations,
		Rules = RestRules,
		OtherClauses = ['$chr_compiled_with_version'(3)|RestOtherClauses]
	; ConstraintDeclarations = RestConstraintDeclarations,
		Rules = RestRules,
		OtherClauses = [Clause|RestOtherClauses]
	),
	partition_clauses(Clauses,RestConstraintDeclarations,RestRules,RestOtherClauses).

'$chr_compiled_with_version'(2).

is_declaration(D, Constraints) :-		%% constraint declaration
	( D = (:- Decl), Decl =.. [F,Cs], F == (chr_constraint) ->
		conj2list(Cs,Constraints0)
	;
		( D = (:- Decl) ->
			Decl =.. [constraints,Cs]
		;
			D =.. [constraints,Cs]
		),
		conj2list(Cs,Constraints0),
		chr_warning(deprecated(D),'Instead use :- chr_constraint ~w.\n',[Cs])
	),
	extract_type_mode(Constraints0,Constraints).

extract_type_mode([],[]).
extract_type_mode([F/A|R],[F/A|R2]) :- !,extract_type_mode(R,R2).
extract_type_mode([C0|R],[ConstraintSymbol|R2]) :-
	( C0 = C # Annotation ->
		functor(C,F,A),
		extract_annotation(Annotation,F/A)
	;
		C0 = C,
		functor(C,F,A)
	),
	ConstraintSymbol = F/A,
	C =.. [_|Args],
	extract_types_and_modes(Args,ArgTypes,ArgModes),
	assert_constraint_type(ConstraintSymbol,ArgTypes),
	constraint_mode(ConstraintSymbol,ArgModes),
	extract_type_mode(R,R2).

extract_annotation(stored,Symbol) :-
	stored_assertion(Symbol).
extract_annotation(default(Goal),Symbol) :-
	never_stored_default(Symbol,Goal).

extract_types_and_modes([],[],[]).
extract_types_and_modes([X|R],[T|R2],[M|R3]) :-
	extract_type_and_mode(X,T,M),
	extract_types_and_modes(R,R2,R3).

extract_type_and_mode(+(T),T,(+)) :- !.
extract_type_and_mode(?(T),T,(?)) :- !.
extract_type_and_mode(-(T),T,(-)) :- !.
extract_type_and_mode((+),any,(+)) :- !.
extract_type_and_mode((?),any,(?)) :- !.
extract_type_and_mode((-),any,(-)) :- !.
extract_type_and_mode(Illegal,_,_) :-
    chr_error(syntax(Illegal),'Illegal mode/type declaration.\n\tCorrect syntax is +type, -type or ?type\n\tor +, - or ?.\n',[]).

is_chr_declaration(Declaration) :-
	Declaration = (:- chr_declaration Decl),
	( Decl = (Pattern ---> Information) ->
	        background_info(Pattern,Information)
	; Decl = Information ->
	        background_info([Information])
	).
is_type_definition(Declaration) :-
	is_type_definition(Declaration,Result),
	assert_type_definition(Result).

assert_type_definition(typedef(Name,DefList)) :- type_definition(Name,DefList).
assert_type_definition(alias(Alias,Name))     :- type_alias(Alias,Name).

is_type_definition(Declaration,Result) :-
	( Declaration = (:- TDef) ->
	      true
	;
	      Declaration = TDef
	),
	TDef =.. [chr_type,TypeDef],
	( TypeDef = (Name ---> Def) ->
	        tdisj2list(Def,DefList),
		Result = typedef(Name,DefList)
	; TypeDef = (Alias == Name) ->
		Result = alias(Alias,Name)
	;
		Result = typedef(TypeDef,[]),
		chr_warning(syntax,'Empty type definition `~w\'.\nAre you sure you want to declare a phantom type?\n',[Declaration])
	).

%%	tdisj2list(+Goal,-ListOfGoals) is det.
%
%	no removal of fails, e.g. :- type bool --->  true ; fail.
tdisj2list(Conj,L) :-
	tdisj2list(Conj,L,[]).

tdisj2list(Conj,L,T) :-
	Conj = (G1;G2), !,
	tdisj2list(G1,L,T1),
	tdisj2list(G2,T1,T).
tdisj2list(G,[G | T],T).


%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	parse_rule(+term,-pragma_rule) is semidet.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
parse_rule(RI,R) :-				%% name @ rule
	RI = (Name @ RI2), !,
	rule(RI2,yes(Name),R).
parse_rule(RI,R) :-
	rule(RI,no,R).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	parse_rule(+term,-pragma_rule) is semidet.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
rule(RI,Name,R) :-
	RI = (RI2 pragma P), !,			%% pragmas
	( var(P) ->
		Ps = [_]			% intercept variable
	;
		conj2list(P,Ps)
	),
	inc_rule_count(RuleCount),
	R = pragma(R1,IDs,Ps,Name,RuleCount),
	is_rule(RI2,R1,IDs,R).
rule(RI,Name,R) :-
	inc_rule_count(RuleCount),
	R = pragma(R1,IDs,[],Name,RuleCount),
	is_rule(RI,R1,IDs,R).

is_rule(RI,R,IDs,RC) :-				%% propagation rule
   RI = (H ==> B), !,
   conj2list(H,Head2i),
   get_ids(Head2i,IDs2,Head2,RC),
   IDs = ids([],IDs2),
   (   B = (G | RB) ->
       R = rule([],Head2,G,RB)
   ;
       R = rule([],Head2,true,B)
   ).
is_rule(RI,R,IDs,RC) :-				%% simplification/simpagation rule
   RI = (H <=> B), !,
   (   B = (G | RB) ->
       Guard = G,
       Body  = RB
   ;   Guard = true,
       Body = B
   ),
   (   H = (H1 \ H2) ->
       conj2list(H1,Head2i),
       conj2list(H2,Head1i),
       get_ids(Head2i,IDs2,Head2,0,N,RC),
       get_ids(Head1i,IDs1,Head1,N,_,RC),
       IDs = ids(IDs1,IDs2)
   ;   conj2list(H,Head1i),
       Head2 = [],
       get_ids(Head1i,IDs1,Head1,RC),
       IDs = ids(IDs1,[])
   ),
   R = rule(Head1,Head2,Guard,Body).

get_ids(Cs,IDs,NCs,RC) :-
	get_ids(Cs,IDs,NCs,0,_,RC).

get_ids([],[],[],N,N,_).
get_ids([C|Cs],[N|IDs],[NC|NCs],N,NN,RC) :-
	( C = (NC # N1) ->
		( var(N1) ->
			N1 = N
		;
			check_direct_pragma(N1,N,RC)
		)
	;
		NC = C
	),
	M is N + 1,
	get_ids(Cs,IDs,NCs, M,NN,RC).

check_direct_pragma(passive,Id,PragmaRule) :- !,
	PragmaRule = pragma(_,_,_,_,RuleNb),
	passive(RuleNb,Id).
check_direct_pragma(Abbrev,Id,PragmaRule) :-
	( direct_pragma(FullPragma),
	  atom_concat(Abbrev,Remainder,FullPragma) ->
		chr_warning(problem_pragma(Abbrev,PragmaRule),'completed `~w\' to `~w\'\n',[Abbrev,FullPragma])
	;
		chr_warning(unsupported_pragma(Abbrev,PragmaRule),'',[])
	).

direct_pragma(passive).

is_module_declaration((:- module(Mod)),Mod).
is_module_declaration((:- module(Mod,_)),Mod).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Add constraints
add_constraints([]).
add_constraints([C|Cs]) :-
	max_occurrence(C,0),
	C = _/A,
	length(Mode,A),
	set_elems(Mode,?),
	constraint_mode(C,Mode),
	add_constraints(Cs).

% Add rules
add_rules([]).
add_rules([Rule|Rules]) :-
	Rule = pragma(_,_,_,_,RuleNb),
	rule(RuleNb,Rule),
	add_rules(Rules).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Some input verification:

check_declared_constraints(Constraints) :-
	tree_set_empty(Acc),
	check_declared_constraints(Constraints,Acc).

check_declared_constraints([],_).
check_declared_constraints([C|Cs],Acc) :-
	( tree_set_memberchk(C,Acc) ->
		chr_error(syntax(C),'Constraint multiply defined: ~w.\n\tRemove redundant declaration!\n',[C])
	;
		true
	),
	tree_set_add(Acc,C,NAcc),
	check_declared_constraints(Cs,NAcc).

%%  - all constraints in heads are declared constraints
%%  - all passive pragmas refer to actual head constraints

check_rules(PragmaRules,AstRules,Decls) :-
	maplist(check_rule(Decls),PragmaRules,AstRules).

check_rule(Decls,PragmaRule,AstRule) :-
	PragmaRule = pragma(_Rule,_IDs,Pragmas,_Name,_N),
	check_ast_rule_indexing(AstRule,PragmaRule),
	% check_rule_indexing(PragmaRule),
	check_ast_trivial_propagation_rule(AstRule,PragmaRule),
	% check_trivial_propagation_rule(PragmaRule),
	check_ast_head_constraints(AstRule,Decls,PragmaRule),
	% Rule = rule(H1,H2,_,_),
	% check_head_constraints(H1,Decls,PragmaRule),
	% check_head_constraints(H2,Decls,PragmaRule),
	check_pragmas(Pragmas,PragmaRule).

%-------------------------------------------------------------------------------
%	Make all heads passive in trivial propagation rule
%	... ==> ... | true.
check_ast_trivial_propagation_rule(AstRule,PragmaRule) :-
	AstRule = ast_rule(AstHead,_,_,AstBody,_),
	( AstHead = propagation(_),
          AstBody == [] ->
		chr_warning(weird_program,'Ignoring propagation rule with empty body: ~@.\n\t\n',[format_rule(PragmaRule)]),
		set_rule_passive(PragmaRule)
	;
		true
	).

set_rule_passive(PragmaRule) :-
	PragmaRule = pragma(_Rule,_IDs,_Pragmas,_Name,RuleNb),
	set_all_passive(RuleNb).

check_trivial_propagation_rule(PragmaRule) :-
	PragmaRule = pragma(Rule,IDs,Pragmas,Name,RuleNb),
	( Rule = rule([],_,_,true) ->
		chr_warning(weird_program,'Ignoring propagation rule with empty body: ~@.\n\t\n',[format_rule(PragmaRule)]),
		set_all_passive(RuleNb)
	;
		true
	).

%-------------------------------------------------------------------------------
check_ast_head_constraints(ast_rule(AstHead,_,_,_,_),Decls,PragmaRule) :-
	check_ast_head_constraints_(AstHead,Decls,PragmaRule).

check_ast_head_constraints_(simplification(AstConstraints),Decls,PragmaRule) :-
	maplist(check_ast_head_constraint(Decls,PragmaRule),AstConstraints).
check_ast_head_constraints_(propagation(AstConstraints),Decls,PragmaRule) :-
	maplist(check_ast_head_constraint(Decls,PragmaRule),AstConstraints).
check_ast_head_constraints_(simpagation(AstConstraints1,AstConstraints2),Decls,PragmaRule) :-
	maplist(check_ast_head_constraint(Decls,PragmaRule),AstConstraints1),
	maplist(check_ast_head_constraint(Decls,PragmaRule),AstConstraints2).

check_ast_head_constraint(Decls,PragmaRule,chr_constraint(Symbol,_,Constraint)) :-
	( memberchk(Symbol,Decls) ->
		true
	;
		chr_error(syntax(Constraint),'Undeclared constraint ~w in head of ~@.\n\tConstraint should be one of ~w.\n', [F/A,format_rule(PragmaRule),Decls])
	).

check_head_constraints([],_,_).
check_head_constraints([Constr|Rest],Decls,PragmaRule) :-
	functor(Constr,F,A),
	( memberchk(F/A,Decls) ->
		check_head_constraints(Rest,Decls,PragmaRule)
	;
		chr_error(syntax(Constr),'Undeclared constraint ~w in head of ~@.\n\tConstraint should be one of ~w.\n', [F/A,format_rule(PragmaRule),Decls])
	).
%-------------------------------------------------------------------------------

check_pragmas([],_).
check_pragmas([Pragma|Pragmas],PragmaRule) :-
	check_pragma(Pragma,PragmaRule),
	check_pragmas(Pragmas,PragmaRule).

check_pragma(Pragma,PragmaRule) :-
	var(Pragma), !,
	chr_error(syntax(Pragma),'Invalid pragma ~w in ~@.\n\tPragma should not be a variable!\n',[Pragma,format_rule(PragmaRule)]).
check_pragma(passive(ID), PragmaRule) :-
	!,
	PragmaRule = pragma(_,ids(IDs1,IDs2),_,_,RuleNb),
	( memberchk_eq(ID,IDs1) ->
		true
	; memberchk_eq(ID,IDs2) ->
		true
	;
		chr_error(syntax(ID),'Invalid identifier ~w in pragma passive in ~@.\n', [ID,format_rule(PragmaRule)])
	),
	passive(RuleNb,ID).

check_pragma(mpassive(IDs), PragmaRule) :-
	!,
	PragmaRule = pragma(_,_,_,_,RuleNb),
	chr_warning(experimental,'Experimental pragma ~w. Use with care!\n',[mpassive(IDs)]),
	maplist(passive(RuleNb),IDs).

check_pragma(Pragma, PragmaRule) :-
	Pragma = already_in_heads,
	!,
	chr_warning(unsupported_pragma(Pragma,PragmaRule),'Termination and correctness may be affected.\n',[]).

check_pragma(Pragma, PragmaRule) :-
	Pragma = already_in_head(_),
	!,
	chr_warning(unsupported_pragma(Pragma,PragmaRule),'Termination and correctness may be affected.\n',[]).

check_pragma(Pragma, PragmaRule) :-
	Pragma = no_history,
	!,
	chr_warning(experimental,'Experimental pragma no_history. Use with care!\n',[]),
	PragmaRule = pragma(_,_,_,_,N),
	no_history(N).

check_pragma(Pragma, PragmaRule) :-
	Pragma = history(HistoryName,IDs),
	!,
	PragmaRule = pragma(_,ids(IDs1,IDs2),_,_,RuleNb),
	chr_warning(experimental,'Experimental pragma ~w. Use with care!\n',[Pragma]),
	( IDs1 \== [] ->
		chr_error(syntax(Pragma),'Pragma history only implemented for propagation rules.\n',[])
	; \+ atom(HistoryName) ->
		chr_error(syntax(Pragma),'Illegal argument for pragma history: ~w is not an atom (rule number ~w).\n',[HistoryName,RuleNb])
	; \+ is_set(IDs) ->
		chr_error(syntax(Pragma),'Illegal argument for pragma history: ~w is not a set (rule number ~w).\n',[IDs,RuleNb])
	; check_history_pragma_ids(IDs,IDs1,IDs2) ->
		history(RuleNb,HistoryName,IDs)
	;
		chr_error(syntax(Pragma),'Invalid identifier(s) in pragma ~w of rule number ~w.\n',[Pragma,RuleNb])
	).
check_pragma(Pragma,PragmaRule) :-
	Pragma = line_number(LineNumber),
	!,
	PragmaRule = pragma(_,_,_,_,RuleNb),
	line_number(RuleNb,LineNumber).

check_history_pragma_ids([], _, _).
check_history_pragma_ids([ID|IDs],IDs1,IDs2) :-
	( memberchk_eq(ID,IDs2) ; memberchk_eq(ID,IDs1) ),
	check_history_pragma_ids(IDs,IDs1,IDs2).

check_pragma(Pragma,PragmaRule) :-
	chr_error(syntax(Pragma),'Unknown pragma ~w in ~@.\n', [Pragma,format_rule(PragmaRule)]).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%	no_history(+RuleNb) is det.
:- chr_constraint no_history/1.
:- chr_option(mode,no_history(+)).
:- chr_option(type_declaration,no_history(int)).

%%	has_no_history(+RuleNb) is semidet.
:- chr_constraint has_no_history/1.
:- chr_option(mode,has_no_history(+)).
:- chr_option(type_declaration,has_no_history(int)).

no_history(RuleNb) \ has_no_history(RuleNb) <=> true.
has_no_history(_) <=> fail.

:- chr_constraint history/3.
:- chr_option(mode,history(+,+,+)).
:- chr_option(type_declaration,history(any,any,list)).

:- chr_constraint named_history/3.

history(RuleNb,_,_), history(RuleNb,_,_) ==>
	chr_error(syntax,'Only one pragma history allowed per rule (rule number ~w)\n',[RuleNb]).	%'

history(RuleNb1,Name,IDs1), history(RuleNb2,Name,IDs2) ==>
	length(IDs1,L1), length(IDs2,L2),
	( L1 \== L2 ->
		chr_error(syntax,'The history named ~w does not always range over an equal amount of occurrences.\n',[Name])
	;
		test_named_history_id_pairs(RuleNb1,IDs1,RuleNb2,IDs2)
	).

test_named_history_id_pairs(_, [], _, []).
test_named_history_id_pairs(RuleNb1, [ID1|IDs1], RuleNb2, [ID2|IDs2]) :-
	test_named_history_id_pair(RuleNb1,ID1,RuleNb2,ID2),
	test_named_history_id_pairs(RuleNb1,IDs1,RuleNb2,IDs2).

:- chr_constraint test_named_history_id_pair/4.
:- chr_option(mode,test_named_history_id_pair(+,+,+,+)).

occurrence(C,_,RuleNb1,ID1,_), occurrence(C,_,RuleNb2,ID2,_)
   \ test_named_history_id_pair(RuleNb1,ID1,RuleNb2,ID2) <=> true.
test_named_history_id_pair(RuleNb1,ID1,RuleNb2,ID2) <=>
	chr_error(syntax,'Occurrences of shared history in rules number ~w and ~w do not correspond\n', [RuleNb2,RuleNb1]).

history(RuleNb,Name,IDs) \ named_history(RuleNb,QName,QIDs) <=> QName = Name, QIDs = IDs.
named_history(_,_,_) <=> fail.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


format_rule(PragmaRule) :-
	PragmaRule = pragma(_,_,_,MaybeName,RuleNumber),
	( MaybeName = yes(Name) ->
		write('rule '), write(Name)
	;
		write('rule number '), write(RuleNumber)
	),
	get_line_number(RuleNumber,LineNumber),
	write(' (line '),
	write(LineNumber),
	write(')').

check_ast_rule_indexing(AstRule,PragmaRule) :-
	AstRule = ast_rule(AstHead,AstGuard,_,_,_),
	tree_set_empty(EmptyVarSet),
	ast_head_variables(AstHead,EmptyVarSet,VarSet),
	ast_remove_anti_monotonic_guards(AstGuard,VarSet,MonotonicAstGuard),
	ast_term_list_variables(MonotonicAstGuard,EmptyVarSet,GuardVarSet),
	check_ast_head_indexing(AstHead,GuardVarSet),
	% check_indexing(H1,NG-H2),
	% check_indexing(H2,NG-H1),
	% EXPERIMENT
	( chr_pp_flag(term_indexing,on) ->
		PragmaRule = pragma(Rule,_,_,_,_),
		Rule = rule(H1,H2,G,_),
		term_variables(H1-H2,HeadVars),
		remove_anti_monotonic_guards(G,HeadVars,NG),
		term_variables(NG,GuardVariables),
		append(H1,H2,Heads),
		check_specs_indexing(Heads,GuardVariables,Specs)
	;
		true
	).

check_ast_head_indexing(simplification(H1),VarSet) :-
	check_ast_indexing(H1,VarSet).
check_ast_head_indexing(propagation(H2),VarSet) :-
	check_ast_indexing(H2,VarSet).
check_ast_head_indexing(simpagation(H1,H2),VarSet) :-
	ast_constraint_list_variables(H2,VarSet,VarSet1),
	check_ast_indexing(H1,VarSet1),
	ast_constraint_list_variables(H1,VarSet,VarSet2),
	check_ast_indexing(H2,VarSet2).

check_rule_indexing(PragmaRule) :-
	PragmaRule = pragma(Rule,_,_,_,_),
	Rule = rule(H1,H2,G,_),
	term_variables(H1-H2,HeadVars),
	remove_anti_monotonic_guards(G,HeadVars,NG),
	check_indexing(H1,NG-H2),
	check_indexing(H2,NG-H1),
	% EXPERIMENT
	( chr_pp_flag(term_indexing,on) ->
		term_variables(NG,GuardVariables),
		append(H1,H2,Heads),
		check_specs_indexing(Heads,GuardVariables,Specs)
	;
		true
	).

:- chr_constraint indexing_spec/2.
:- chr_option(mode,indexing_spec(+,+)).

:- chr_constraint get_indexing_spec/2.
:- chr_option(mode,get_indexing_spec(+,-)).


indexing_spec(FA,Spec) \ get_indexing_spec(FA,R) <=> R = Spec.
get_indexing_spec(_,Spec) <=> Spec = [].

indexing_spec(FA,Specs1), indexing_spec(FA,Specs2)
	<=>
		append(Specs1,Specs2,Specs),
		indexing_spec(FA,Specs).

remove_anti_monotonic_guards(G,Vars,NG) :-
	conj2list(G,GL),
	remove_anti_monotonic_guard_list(GL,Vars,NGL),
	list2conj(NGL,NG).

remove_anti_monotonic_guard_list([],_,[]).
remove_anti_monotonic_guard_list([G|Gs],Vars,NGs) :-
	( G = var(X), memberchk_eq(X,Vars) ->
		NGs = RGs
	;
		NGs = [G|RGs]
	),
	remove_anti_monotonic_guard_list(Gs,Vars,RGs).

ast_remove_anti_monotonic_guards([],_,[]).
ast_remove_anti_monotonic_guards([G|Gs],VarSet,NGs) :-
	( G = compound(var,1,[X],_),
          ast_var_memberchk(X,VarSet) ->
		NGs = RGs
	;
		NGs = [G|RGs]
	),
	ast_remove_anti_monotonic_guards(Gs,VarSet,RGs).
%-------------------------------------------------------------------------------

check_ast_indexing([],_).
check_ast_indexing([Head|Heads],VarSet) :-
	Head = chr_constraint(Symbol,Args,_Constraint),
	ast_constraint_list_variables(Heads,VarSet,VarSet1),
	check_ast_indexing(Args,1,Symbol,VarSet1),
	ast_constraint_variables(Head,VarSet,NVarSet),
	check_ast_indexing(Heads,NVarSet).

check_ast_indexing([],_,_,_).
check_ast_indexing([Arg|Args],I,Symbol,VarSet) :-
	( is_indexed_argument(Symbol,I) ->
		true
	; ast_nonvar(Arg) ->
		indexed_argument(Symbol,I)
	; % ast_var(Arg)  ->
		ast_term_list_variables(Args,VarSet,VarSet1),
		( ast_var_memberchk(Arg,VarSet1) ->
			indexed_argument(Symbol,I)
		;
			true
		)
	),
	J is I + 1,
	ast_term_variables(Arg,VarSet,NVarSet),
	check_ast_indexing(Args,J,Symbol,NVarSet).

% check_indexing(list(chr_constraint),variables)
check_indexing([],_).
check_indexing([Head|Heads],Other) :-
	functor(Head,F,A),
	Head =.. [_|Args],
	term_variables(Heads-Other,OtherVars),
	check_indexing(Args,1,F/A,OtherVars),
	check_indexing(Heads,[Head|Other]).

check_indexing([],_,_,_).
check_indexing([Arg|Args],I,FA,OtherVars) :-
	( is_indexed_argument(FA,I) ->
		true
	; nonvar(Arg) ->
		indexed_argument(FA,I)
	; % var(Arg) ->
		term_variables(Args,ArgsVars),
		append(ArgsVars,OtherVars,RestVars),
		( memberchk_eq(Arg,RestVars) ->
			indexed_argument(FA,I)
		;
			true
		)
	),
	J is I + 1,
	term_variables(Arg,NVars),
	append(NVars,OtherVars,NOtherVars),
	check_indexing(Args,J,FA,NOtherVars).
%-------------------------------------------------------------------------------

check_specs_indexing([],_,[]).
check_specs_indexing([Head|Heads],Variables,Specs) :-
	Specs = [Spec|RSpecs],
	term_variables(Heads,OtherVariables,Variables),
	check_spec_indexing(Head,OtherVariables,Spec),
	term_variables(Head,NVariables,Variables),
	check_specs_indexing(Heads,NVariables,RSpecs).

check_spec_indexing(Head,OtherVariables,Spec) :-
	functor(Head,F,A),
	Spec = spec(F,A,ArgSpecs),
	Head =.. [_|Args],
	check_args_spec_indexing(Args,1,OtherVariables,ArgSpecs),
	indexing_spec(F/A,[ArgSpecs]).

check_args_spec_indexing([],_,_,[]).
check_args_spec_indexing([Arg|Args],I,OtherVariables,ArgSpecs) :-
	term_variables(Args,Variables,OtherVariables),
	( check_arg_spec_indexing(Arg,I,Variables,ArgSpec) ->
		ArgSpecs = [ArgSpec|RArgSpecs]
	;
		ArgSpecs = RArgSpecs
	),
	J is I + 1,
	term_variables(Arg,NOtherVariables,OtherVariables),
	check_args_spec_indexing(Args,J,NOtherVariables,RArgSpecs).

check_arg_spec_indexing(Arg,I,Variables,ArgSpec) :-
	( var(Arg) ->
		memberchk_eq(Arg,Variables),
		ArgSpec = specinfo(I,any,[])
	;
		functor(Arg,F,A),
		ArgSpec = specinfo(I,F/A,[ArgSpecs]),
		Arg =.. [_|Args],
		check_args_spec_indexing(Args,1,Variables,ArgSpecs)
	).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Occurrences

add_occurrences(PragmaRules,AstRules) :-
	maplist(add_rule_occurrences,PragmaRules,AstRules).

add_rule_occurrences(PragmaRule,AstRule) :-
	PragmaRule = pragma(_,IDs,_,_,Nb),
	AstRule    = ast_rule(AstHead,_,_,_,_),
	add_head_occurrences(AstHead,IDs,Nb).

add_head_occurrences(simplification(H1),ids(IDs1,_),Nb) :-
	maplist(add_constraint_occurrence(Nb,simplification),H1,IDs1).
add_head_occurrences(propagation(H2),ids(_,IDs2),Nb) :-
	maplist(add_constraint_occurrence(Nb,propagation),H2,IDs2).
add_head_occurrences(simpagation(H1,H2),ids(IDs1,IDs2),Nb) :-
	maplist(add_constraint_occurrence(Nb,simplification),H1,IDs1),
	maplist(add_constraint_occurrence(Nb,propagation),H2,IDs2).

add_constraint_occurrence(Nb,OccType,Constraint,ID) :-
	Constraint = chr_constraint(Symbol,_,_),
	new_occurrence(Symbol,Nb,ID,OccType).

% add_occurrences([],[]).
% add_occurrences([Rule|Rules],[]) :-
%	Rule = pragma(rule(H1,H2,_,_),ids(IDs1,IDs2),_,_,Nb),
%	add_occurrences(H1,IDs1,simplification,Nb),
%	add_occurrences(H2,IDs2,propagation,Nb),
%	add_occurrences(Rules).
%
% add_occurrences([],[],_,_).
% add_occurrences([H|Hs],[ID|IDs],Type,RuleNb) :-
%	functor(H,F,A),
%	FA = F/A,
%	new_occurrence(FA,RuleNb,ID,Type),
%	add_occurrences(Hs,IDs,Type,RuleNb).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Observation Analysis
%
% CLASSIFICATION
%
%
%
%
%
%

:- chr_constraint observation_analysis/1.
:- chr_option(mode, observation_analysis(+)).

observation_analysis(Cs), rule(RuleNb,PragmaRule) # Id ==>
	PragmaRule = pragma(rule(_,_,Guard,Body),_,_,_,_),
	( chr_pp_flag(store_in_guards, on) ->
		observation_analysis(RuleNb, Guard, guard, Cs)
	;
		true
	),
	observation_analysis(RuleNb, Body, body, Cs)

	pragma passive(Id).
observation_analysis(_) <=> true.

observation_analysis(RuleNb, Term, GB, Cs) :-
	( all_spawned(RuleNb,GB) ->
		true
	; var(Term) ->
		spawns_all(RuleNb,GB)
	; Term = true ->
		true
	; Term = fail ->
		true
	; Term = '!' ->
		true
	; Term = (T1,T2) ->
		observation_analysis(RuleNb,T1,GB,Cs),
		observation_analysis(RuleNb,T2,GB,Cs)
	; Term = (T1;T2) ->
		observation_analysis(RuleNb,T1,GB,Cs),
		observation_analysis(RuleNb,T2,GB,Cs)
	; Term = (T1->T2) ->
		observation_analysis(RuleNb,T1,GB,Cs),
		observation_analysis(RuleNb,T2,GB,Cs)
	; Term = (\+ T) ->
		observation_analysis(RuleNb,T,GB,Cs)
	; functor(Term,F,A), memberchk(F/A,Cs) ->
		spawns(RuleNb,GB,F/A)
	; Term = (_ = _) ->
		spawns_all_triggers(RuleNb,GB)
	; Term = (_ is _) ->
		spawns_all_triggers(RuleNb,GB)
	; builtin_binds_b(Term,Vars) ->
		(  Vars == [] ->
			true
		;
			spawns_all_triggers(RuleNb,GB)
		)
	;
		spawns_all(RuleNb,GB)
	).

:- chr_constraint spawns/3.
:- chr_option(mode, spawns(+,+,+)).
:- chr_type spawns_type ---> guard ; body.
:- chr_option(type_declaration,spawns(any,spawns_type,any)).

:- chr_constraint spawns_all/2, spawns_all_triggers/2.
:- chr_option(mode, spawns_all(+,+)).
:- chr_option(type_declaration,spawns_all(any,spawns_type)).
:- chr_option(mode, spawns_all_triggers(+,+)).
:- chr_option(type_declaration,spawns_all_triggers(any,spawns_type)).

spawns_all(RuleNb,GB) \ spawns_all(RuleNb,GB) <=> true.
spawns_all(RuleNb,guard) \ spawns_all(RuleNb,body) <=> true.
spawns_all_triggers(RuleNb,GB) \ spawns_all_triggers(RuleNb,GB) <=> true.
spawns_all_triggers(RuleNb,guard) \ spawns_all_triggers(RuleNb,body) <=> true.
spawns(RuleNb,GB,C) \ spawns(RuleNb,GB,C) <=> true.
spawns(RuleNb,guard,C) \ spawns(RuleNb,body,C) <=> true.

spawns_all(RuleNb,GB) \ spawns(RuleNb,GB,_) <=> true.
spawns_all(RuleNb,guard) \ spawns(RuleNb,body,_) <=> true.
spawns_all(RuleNb,GB) \ spawns_all_triggers(RuleNb,GB) <=> true.
spawns_all(RuleNb,guard) \ spawns_all_triggers(RuleNb,body) <=> true.

spawns_all_triggers(RuleNb,GB) \ spawns(RuleNb,GB,C) <=> may_trigger(C) | true.
spawns_all_triggers(RuleNb,guard) \ spawns(RuleNb,body,C) <=> may_trigger(C) | true.

spawns_all(RuleNb2,_), occurrence(C1,_,RuleNb2,O,_)#Id
	 \
		spawns(RuleNb1,GB,C1)
	<=>
		\+ is_passive(RuleNb2,O)
	 |
		spawns_all(RuleNb1,GB)
	pragma
		passive(Id).

occurrence(C1,_,RuleNb2,O,_)#Id, spawns_all(RuleNb2,_)
	==>
		\+(\+ spawns_all_triggers_implies_spawns_all),	% in the hope it schedules this guard early...
		\+ is_passive(RuleNb2,O), may_trigger(C1)
	 |
		spawns_all_triggers_implies_spawns_all
	pragma
		passive(Id).

:- chr_constraint spawns_all_triggers_implies_spawns_all/0.
spawns_all_triggers_implies_spawns_all, spawns_all_triggers_implies_spawns_all <=> fail.
spawns_all_triggers_implies_spawns_all \
	spawns_all_triggers(RuleNb,GB) <=> spawns_all(RuleNb,GB).

spawns_all_triggers(RuleNb2,_), occurrence(C1,_,RuleNb2,O,_)#Id
	 \
		spawns(RuleNb1,GB,C1)
	<=>
		may_trigger(C1),
		\+ is_passive(RuleNb2,O)
	 |
		spawns_all_triggers(RuleNb1,GB)
	pragma
		passive(Id).

spawns_all_triggers(RuleNb2,_), occurrence(C1,_,RuleNb2,O,_)#Id,
		spawns(RuleNb1,GB,C1)
	==>
		\+ may_trigger(C1),
		\+ is_passive(RuleNb2,O)
	 |
		spawns_all_triggers(RuleNb1,GB)
	pragma
		passive(Id).

% a bit dangerous this rule: could start propagating too much too soon?
spawns(RuleNb2,_,C2), occurrence(C1,_,RuleNb2,O,_)#Id,
		spawns(RuleNb1,GB,C1)
	==>
		RuleNb1 \== RuleNb2, C1 \== C2,
		\+ is_passive(RuleNb2,O)
	|
		spawns(RuleNb1,GB,C2)
	pragma
		passive(Id).

spawns(RuleNb2,_,C2), occurrence(C1,_,RuleNb2,O,_)#Id,
		spawns_all_triggers(RuleNb1,GB)
	==>
		\+ is_passive(RuleNb2,O), may_trigger(C1), \+ may_trigger(C2)
	 |
		spawns(RuleNb1,GB,C2)
	pragma
		passive(Id).


:- chr_constraint all_spawned/2.
:- chr_option(mode, all_spawned(+,+)).
spawns_all(RuleNb,guard) \ all_spawned(RuleNb,_) <=> true.
spawns_all(RuleNb,GB) \ all_spawned(RuleNb,GB) <=> true.
all_spawned(RuleNb,GB) <=> fail.


% Overview of the supported queries:
%	is_observed(+functor/artiy, +occurrence_number, +(guard;body))
%		only succeeds if the occurrence is observed by the
%		guard resp. body (depending on the last argument) of its rule
%	is_observed(+functor/artiy, +occurrence_number, -)
%		succeeds if the occurrence is observed by either the guard or
%		the body of its rule
%		NOTE: the last argument is NOT bound by this query
%
%	do_is_observed(+functor/artiy,+rule_number,+(guard;body))
%		succeeds if the given constraint is observed by the given
%		guard resp. body
%	do_is_observed(+functor/artiy,+rule_number)
%		succeeds if the given constraint is observed by the given
%		rule (either its guard or its body)


is_observed(C,O) :-
	is_observed(C,O,_),
	ai_is_observed(C,O).

is_stored_in_guard(C,RuleNb) :-
	chr_pp_flag(store_in_guards, on),
	do_is_observed(C,RuleNb,guard).

:- chr_constraint is_observed/3.
:- chr_option(mode, is_observed(+,+,+)).
occurrence(C,O,RuleNb,_,_) \ is_observed(C,O,GB) <=> do_is_observed(C,RuleNb,GB).
is_observed(_,_,_) <=> fail.	% this will not happen in practice


:- chr_constraint do_is_observed/3.
:- chr_option(mode, do_is_observed(+,+,?)).
:- chr_constraint do_is_observed/2.
:- chr_option(mode, do_is_observed(+,+)).

do_is_observed(C,RuleNb,GB) <=> var(GB) | do_is_observed(C,RuleNb).

% (1) spawns_all
% a constraint C is observed if the GB of the rule it occurs in spawns all,
% and some non-passive occurrence of some (possibly other) constraint
% exists in a rule (could be same rule) with at least one occurrence of C

spawns_all(RuleNb,GB),
		occurrence(_,_,RuleNb2,O,_), occurrence(C,_,RuleNb2,_,_)
	 \
		do_is_observed(C,RuleNb,GB)
	 <=>
		\+ is_passive(RuleNb2,O)
	  |
		true.

spawns_all(RuleNb,_),
		occurrence(_,_,RuleNb2,O,_), occurrence(C,_,RuleNb2,_,_)
	 \
		do_is_observed(C,RuleNb)
	 <=>
		\+ is_passive(RuleNb2,O)
	  |
		true.

% (2) spawns
% a constraint C is observed if the GB of the rule it occurs in spawns a
% constraint C2 that occurs non-passively in a rule (possibly the same rule)
% as an occurrence of C

spawns(RuleNb,GB,C2),
		occurrence(C2,_,RuleNb2,O,_), occurrence(C,_,RuleNb2,_,_)
	 \
		do_is_observed(C,RuleNb,GB)
	<=>
		\+ is_passive(RuleNb2,O)
	 |
		true.

spawns(RuleNb,_,C2),
		occurrence(C2,_,RuleNb2,O,_), occurrence(C,_,RuleNb2,_,_)
	 \
		do_is_observed(C,RuleNb)
	<=>
		\+ is_passive(RuleNb2,O)
	 |
		true.

% (3) spawns_all_triggers
% a constraint C is observed if the GB of the rule it occurs in spawns all triggers
% and some non-passive occurrence of some (possibly other) constraint that may trigger
% exists in a rule (could be same rule) with at least one occurrence of C

spawns_all_triggers(RuleNb,GB),
		occurrence(C2,_,RuleNb2,O,_), occurrence(C,_,RuleNb2,_,_)
	 \
		do_is_observed(C,RuleNb,GB)
	<=>
		\+ is_passive(RuleNb2,O), may_trigger(C2)
	 |
		true.

spawns_all_triggers(RuleNb,_),
		occurrence(C2,_,RuleNb2,O,_), occurrence(C,_,RuleNb2,_,_)
	 \
		do_is_observed(C,RuleNb)
	<=>
		\+ is_passive(RuleNb2,O), may_trigger(C2)
	 |
		true.

% (4) conservativeness
do_is_observed(_,_,_) <=> chr_pp_flag(observation_analysis,off).
do_is_observed(_,_) <=> chr_pp_flag(observation_analysis,off).


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%
%% Generated predicates
%%	attach_$CONSTRAINT
%%	attach_increment
%%	detach_$CONSTRAINT
%%	attr_unify_hook

%%	attach_$CONSTRAINT
generate_attach_detach_a_constraint_all([],[]).
generate_attach_detach_a_constraint_all([Constraint|Constraints],Clauses) :-
	( ( chr_pp_flag(debugable,on) ; is_stored(Constraint), \+ only_ground_indexed_arguments(Constraint), \+ get_store_type(Constraint,var_assoc_store(_,_)) ) ->
		generate_attach_a_constraint(Constraint,Clauses1),
		generate_detach_a_constraint(Constraint,Clauses2)
	;
		Clauses1 = [],
		Clauses2 = []
	),
	generate_attach_detach_a_constraint_all(Constraints,Clauses3),
	append([Clauses1,Clauses2,Clauses3],Clauses).

generate_attach_a_constraint(Constraint,[Clause1,Clause2]) :-
	generate_attach_a_constraint_nil(Constraint,Clause1),
	generate_attach_a_constraint_cons(Constraint,Clause2).

attach_constraint_atom(FA,Vars,Susp,Atom) :-
	make_name('attach_',FA,Name),
	Atom =.. [Name,Vars,Susp].

generate_attach_a_constraint_nil(FA,Clause) :-
	Clause = (Head :- true),
	attach_constraint_atom(FA,[],_,Head).

generate_attach_a_constraint_cons(FA,Clause) :-
	Clause = (Head :- Body),
	attach_constraint_atom(FA,[Var|Vars],Susp,Head),
	attach_constraint_atom(FA,Vars,Susp,RecursiveCall),
	Body = ( AttachBody, Subscribe, RecursiveCall ),
	get_max_constraint_index(N),
	( N == 1 ->
		generate_attach_body_1(FA,Var,Susp,AttachBody)
	;
		generate_attach_body_n(FA,Var,Susp,AttachBody)
	),
	% SWI-Prolog specific code
	chr_pp_flag(solver_events,NMod),
	( NMod \== none ->
		Args = [[Var|_],Susp],
		get_target_module(Mod),
		use_auxiliary_predicate(run_suspensions),
		Subscribe = clp_events:subscribe(Var,NMod,Mod,Mod:'$run_suspensions'([Susp]))
	;
		Subscribe = true
	).

generate_attach_body_1(FA,Var,Susp,Body) :-
	get_target_module(Mod),
	Body =
	(   get_attr(Var, Mod, Susps) ->
            put_attr(Var, Mod, [Susp|Susps])
        ;
            put_attr(Var, Mod, [Susp])
	).

generate_attach_body_n(F/A,Var,Susp,Body) :-
	chr_pp_flag(experiment,off), !,
	get_constraint_index(F/A,Position),
	get_max_constraint_index(Total),
	get_target_module(Mod),
	add_attr(Total,Susp,Position,TAttr,AddGoal,NTAttr),
	singleton_attr(Total,Susp,Position,NewAttr3),
	Body =
	( get_attr(Var,Mod,TAttr) ->
		AddGoal,
		put_attr(Var,Mod,NTAttr)
	;
		put_attr(Var,Mod,NewAttr3)
	), !.
generate_attach_body_n(F/A,Var,Susp,Body) :-
	chr_pp_flag(experiment,on), !,
	get_constraint_index(F/A,Position),
	or_pattern(Position,Pattern),
	Position1 is Position + 1,
	get_max_constraint_index(Total),
	get_target_module(Mod),
	singleton_attr(Total,Susp,Position,NewAttr3),
	Body =
	( get_attr(Var,Mod,TAttr) ->
		arg(1,TAttr,BitVector),
		arg(Position1,TAttr,Susps),
		NBitVector is BitVector \/ Pattern,
		setarg(1,TAttr,NBitVector),
		setarg(Position1,TAttr,[Susp|Susps])
	;
		put_attr(Var,Mod,NewAttr3)
	), !.

%%	detach_$CONSTRAINT
generate_detach_a_constraint(Constraint,[Clause1,Clause2]) :-
	generate_detach_a_constraint_nil(Constraint,Clause1),
	generate_detach_a_constraint_cons(Constraint,Clause2).

detach_constraint_atom(FA,Vars,Susp,Atom) :-
	make_name('detach_',FA,Name),
	Atom =.. [Name,Vars,Susp].

generate_detach_a_constraint_nil(FA,Clause) :-
	Clause = ( Head :- true),
	detach_constraint_atom(FA,[],_,Head).

generate_detach_a_constraint_cons(FA,Clause) :-
	Clause = (Head :- Body),
	detach_constraint_atom(FA,[Var|Vars],Susp,Head),
	detach_constraint_atom(FA,Vars,Susp,RecursiveCall),
	Body = ( DetachBody, RecursiveCall ),
	get_max_constraint_index(N),
	( N == 1 ->
		generate_detach_body_1(FA,Var,Susp,DetachBody)
	;
		generate_detach_body_n(FA,Var,Susp,DetachBody)
	).

generate_detach_body_1(FA,Var,Susp,Body) :-
	get_target_module(Mod),
	Body =
	( get_attr(Var,Mod,Susps) ->
		'chr sbag_del_element'(Susps,Susp,NewSusps),
		( NewSusps == [] ->
			del_attr(Var,Mod)
		;
			put_attr(Var,Mod,NewSusps)
		)
	;
		true
	).

generate_detach_body_n(F/A,Var,Susp,Body) :-
	get_constraint_index(F/A,Position),
	get_max_constraint_index(Total),
	rem_attr(Total,Var,Susp,Position,TAttr,RemGoal),
	get_target_module(Mod),
	Body =
	( get_attr(Var,Mod,TAttr) ->
		RemGoal
	;
		true
	), !.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%-------------------------------------------------------------------------------
%%	generate_indexed_variables_body(+ConstraintSymbol,+ArgList,-Body,-VarList) is det.
:- chr_constraint generate_indexed_variables_body/4.
:- chr_option(mode,generate_indexed_variables_body(+,?,+,?)).
:- chr_option(type_declaration,generate_indexed_variables_body(constraint,any,any,any)).
%-------------------------------------------------------------------------------
constraint_mode(F/A,ArgModes) \ generate_indexed_variables_body(F/A,Args,Body,Vars) <=>
	get_indexing_spec(F/A,Specs),
	( chr_pp_flag(term_indexing,on) ->
		spectermvars(Specs,Args,F,A,Body,Vars)
	;
		get_constraint_type_det(F/A,ArgTypes),
		create_indexed_variables_body(Args,ArgModes,ArgTypes,Vars,1,F/A,MaybeBody,N),
		( MaybeBody == empty ->
			Body = true,
			Vars = []
		; N == 0 ->
			( Args = [Term] ->
				true
			;
				Term =.. [term|Args]
			),
			Body = term_variables(Term,Vars)
		;
			MaybeBody = Body
		)
	).
generate_indexed_variables_body(FA,_,_,_) <=>
	chr_error(internal,'generate_indexed_variables_body: missing mode info for ~w.\n',[FA]).
%===============================================================================

create_indexed_variables_body([],[],[],_,_,_,empty,0).
create_indexed_variables_body([V|Vs],[Mode|Modes],[Type|Types],Vars,I,FA,Body,N) :-
	J is I + 1,
	create_indexed_variables_body(Vs,Modes,Types,Tail,J,FA,RBody,M),
	( Mode == (?),
          is_indexed_argument(FA,I) ->
		( atomic_type(Type) ->
			Body =
			(
				( var(V) ->
					Vars = [V|Tail]
				;
					Vars = Tail
				),
				Continuation
			),
			( RBody == empty ->
				Continuation = true, Tail = []
			;
				Continuation = RBody
			)
		;
			( RBody == empty ->
				Body = term_variables(V,Vars)
			;
				Body = (term_variables(V,Vars,Tail),RBody)
			)
		),
		N = M
	; Mode == (-), is_indexed_argument(FA,I) ->
		( RBody == empty ->
			Body = (Vars = [V])
		;
			Body = (Vars = [V|Tail],RBody)
		),
		N is M + 1
	;
		Vars = Tail,
		Body = RBody,
		N is M + 1
	).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% EXPERIMENTAL
spectermvars(Specs,Args,F,A,Goal,Vars) :-
	spectermvars(Args,1,Specs,F,A,Vars,[],Goal).

spectermvars([],B,_,_,A,L,L,true) :- B > A, !.
spectermvars([Arg|Args],I,Specs,F,A,L,T,Goal) :-
	Goal = (ArgGoal,RGoal),
	argspecs(Specs,I,TempArgSpecs,RSpecs),
	merge_argspecs(TempArgSpecs,ArgSpecs),
	arggoal(ArgSpecs,Arg,ArgGoal,L,L1),
	J is I + 1,
	spectermvars(Args,J,RSpecs,F,A,L1,T,RGoal).

argspecs([],_,[],[]).
argspecs([[]|Rest],I,ArgSpecs,RestSpecs) :-
	argspecs(Rest,I,ArgSpecs,RestSpecs).
argspecs([[specinfo(J,Spec,Args)|Specs]|Rest],I,ArgSpecs,RestSpecs) :-
	( I == J ->
		ArgSpecs = [specinfo(J,Spec,Args)|RArgSpecs],
		( Specs = [] ->
			RRestSpecs = RestSpecs
		;
			RestSpecs = [Specs|RRestSpecs]
		)
	;
		ArgSpecs = RArgSpecs,
		RestSpecs = [[specinfo(J,Spec,Args)|Specs]|RRestSpecs]
	),
	argspecs(Rest,I,RArgSpecs,RRestSpecs).

merge_argspecs(In,Out) :-
	sort(In,Sorted),
	merge_argspecs_(Sorted,Out).

merge_argspecs_([],[]).
merge_argspecs_([X],R) :- !, R = [X].
merge_argspecs_([specinfo(I,F1,A1),specinfo(I,F2,A2)|Rest],R) :-
	( (F1 == any ; F2 == any) ->
		merge_argspecs_([specinfo(I,any,[])|Rest],R)
	; F1 == F2 ->
		append(A1,A2,A),
		merge_argspecs_([specinfo(I,F1,A)|Rest],R)
	;
		R = [specinfo(I,F1,A1)|RR],
		merge_argspecs_([specinfo(I,F2,A2)|Rest],RR)
	).

arggoal(List,Arg,Goal,L,T) :-
	( List == [] ->
		L = T,
		Goal = true
	; List = [specinfo(_,any,_)] ->
		Goal = term_variables(Arg,L,T)
	;
		Goal =
		( var(Arg) ->
			L = [Arg|T]
		;
			Cases
		),
		arggoal_cases(List,Arg,L,T,Cases)
	).

arggoal_cases([],_,L,T,L=T).
arggoal_cases([specinfo(_,FA,ArgSpecs)|Rest],Arg,L,T,Cases) :-
	( ArgSpecs == [] ->
		Cases = RCases
	; ArgSpecs == [[]] ->
		Cases = RCases
	; FA = F/A ->
		Cases = (Case ; RCases),
		functor(Term,F,A),
		Term =.. [_|Args],
		Case = (Arg = Term -> ArgsGoal),
		spectermvars(Args,1,ArgSpecs,F,A,L,T,ArgsGoal)
	),
	arggoal_cases(Rest,Arg,L,T,RCases).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

generate_extra_clauses(Constraints,List) :-
	generate_activate_clauses(Constraints,List,Tail0),
	generate_remove_clauses(Constraints,Tail0,Tail1),
	generate_allocate_clauses(Constraints,Tail1,Tail2),
	generate_insert_constraint_internal_clauses(Constraints,Tail2,Tail3),
	generate_novel_production(Tail3,Tail4),
	generate_extend_history(Tail4,Tail5),
	generate_run_suspensions_clauses(Constraints,Tail5,Tail6),
	generate_empty_named_history_initialisations(Tail6,Tail7),
	Tail7 = [].

%~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
% remove_constraint_internal/[1/3]

generate_remove_clauses([],List,List).
generate_remove_clauses([C|Cs],List,Tail) :-
	generate_remove_clause(C,List,List1),
	generate_remove_clauses(Cs,List1,Tail).

remove_constraint_goal(Constraint,Susp,Agenda,DeleteNo,DeleteYes,Role,Goal) :-
	uses_state(Constraint,removed),
	( chr_pp_flag(inline_insertremove,off) ->
		use_auxiliary_predicate(remove_constraint_internal,Constraint),
		Goal = ( DeleteGoal, ( Delete == yes -> DeleteYes ; DeleteNo) ),
		remove_constraint_atom(Constraint,Susp,Agenda,Delete,DeleteGoal)
	;
		delay_phase_end(validate_store_type_assumptions,
			generate_remove_body(Constraint,Susp,Agenda,DeleteNo,DeleteYes,Role,Goal)
		)
	).

remove_constraint_atom(Constraint,Susp,Agenda,Delete,Goal) :-
	make_name('$remove_constraint_internal_',Constraint,Name),
	( chr_pp_flag(debugable,off), ( only_ground_indexed_arguments(Constraint) ; get_store_type(Constraint,var_assoc_store(_,_)) ) ->
		Goal =.. [Name, Susp,Delete]
	;
		Goal =.. [Name,Susp,Agenda,Delete]
	).

generate_remove_clause(Constraint,List,Tail) :-
	( is_used_auxiliary_predicate(remove_constraint_internal,Constraint) ->
		List = [RemoveClause|Tail],
		RemoveClause = (Head :- RemoveBody),
		remove_constraint_atom(Constraint,Susp,Agenda,Delete,Head),
		generate_remove_body(Constraint,Susp,Agenda,Delete = no,Delete = yes,active,RemoveBody)
	;
		List = Tail
	).

generate_remove_body(Constraint,Susp,Agenda,DeleteNo,DeleteYes,Role,RemoveBody) :-
	( chr_pp_flag(debugable,off), ( only_ground_indexed_arguments(Constraint) ; get_store_type(Constraint,var_assoc_store(_,_))) ->
		( Role == active ->
			get_update_suspension_field(Constraint,Susp,state,State,removed,GetState,GetStateValue0,UpdateState),
			if_used_state(Constraint,not_stored_yet,GetStateValue0,true,GetStateValue),
			if_used_state(Constraint,not_stored_yet,(State == not_stored_yet -> DeleteNo ; DeleteYes),DeleteYes,MaybeDelete)
		; Role == partner ->
			get_update_suspension_field(Constraint,Susp,state,State,removed,GetState,_,UpdateState),
			GetStateValue = true,
			MaybeDelete = DeleteYes
		),
		RemoveBody =
		(
			GetState,
			GetStateValue,
			UpdateState,
			MaybeDelete
		)
	;
		static_suspension_term(Constraint,Susp2),
		get_static_suspension_term_field(arguments,Constraint,Susp2,Args),
		generate_indexed_variables_body(Constraint,Args,IndexedVariablesBody,Agenda),
		( chr_pp_flag(debugable,on) ->
			Constraint = Functor / _,
			get_static_suspension_term_field(functor,Constraint,Susp2,Functor)
		;
			true
		),
		( Role == active ->
			get_update_static_suspension_field(Constraint,Susp,Susp2,state,State,removed,GetStateValue0,UpdateState),
			if_used_state(Constraint,not_stored_yet,GetStateValue0,true,GetStateValue),
			if_used_state(Constraint,not_stored_yet,(State == not_stored_yet -> Agenda = [], DeleteNo ; IndexedVariablesBody, DeleteYes),(IndexedVariablesBody,DeleteYes),MaybeDelete)
		; Role == partner ->
			get_update_static_suspension_field(Constraint,Susp,Susp2,state,State,removed,_,UpdateState),
			GetStateValue = true,
			MaybeDelete = (IndexedVariablesBody, DeleteYes)
		),
		RemoveBody =
		(
                        Susp = Susp2,
			GetStateValue,
			UpdateState,
			MaybeDelete
		)
	).

%~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
% activate_constraint/4

generate_activate_clauses([],List,List).
generate_activate_clauses([C|Cs],List,Tail) :-
	generate_activate_clause(C,List,List1),
	generate_activate_clauses(Cs,List1,Tail).

activate_constraint_goal(Constraint,StoreAction,Vars,Susp,Generation,Goal) :-
	( chr_pp_flag(inline_insertremove,off) ->
		use_auxiliary_predicate(activate_constraint,Constraint),
		Goal = ( ActivateGoal , (Store == yes -> StoreAction ; true) ),
		activate_constraint_atom(Constraint,Store,Vars,Susp,Generation,ActivateGoal)
	;
		delay_phase_end(validate_store_type_assumptions,
			activate_constraint_body(Constraint,StoreAction,true,Vars,Susp,Generation,Goal)
		)
	).

activate_constraint_atom(Constraint,Store,Vars,Susp,Generation,Goal) :-
	make_name('$activate_constraint_',Constraint,Name),
	( chr_pp_flag(debugable,off), only_ground_indexed_arguments(Constraint) ->
		Goal =.. [Name,Store, Susp]
	; chr_pp_flag(debugable,off), may_trigger(Constraint), get_store_type(Constraint,var_assoc_store(_,_)) ->
		Goal =.. [Name,Store, Susp, Generation]
	; chr_pp_flag(debugable,off), may_trigger(Constraint), get_store_type(Constraint,var_assoc_store(_,_)) ->
		Goal =.. [Name,Store, Vars, Susp, Generation]
	;
		Goal =.. [Name,Store, Vars, Susp]
	).

generate_activate_clause(Constraint,List,Tail) :-
	( is_used_auxiliary_predicate(activate_constraint,Constraint) ->
		List = [Clause|Tail],
		Clause = (Head :- Body),
		activate_constraint_atom(Constraint,Store,Vars,Susp,Generation,Head),
		activate_constraint_body(Constraint,Store = yes, Store = no,Vars,Susp,Generation,Body)
	;
		List = Tail
	).

activate_constraint_body(Constraint,StoreYes,StoreNo,Vars,Susp,Generation,Body) :-
	( chr_pp_flag(debugable,off), may_trigger(Constraint), uses_field(Constraint,generation) ->
		get_update_suspension_field(Constraint,Susp,generation,Gen,Generation,GetGeneration,GetGenerationValue,UpdateGeneration),
		GenerationHandling = (GetGeneration, GetGenerationValue, Generation is Gen+1, UpdateGeneration)
	;
		GenerationHandling = true
	),
	get_update_suspension_field(Constraint,Susp,state,State,active,GetState,GetStateValue0,UpdateState),
	if_used_state(Constraint,not_stored_yet,GetStateValue0,true,GetStateValue),
	( chr_pp_flag(debugable,off), ( only_ground_indexed_arguments(Constraint) ; get_store_type(Constraint,var_assoc_store(_,_))) ->
		if_used_state(Constraint,not_stored_yet,( State == not_stored_yet -> StoreYes ; StoreNo ),StoreNo,StoreVarsGoal)
	;
		get_dynamic_suspension_term_field(arguments,Constraint,Susp,Arguments,ArgumentsGoal),
		generate_indexed_variables_body(Constraint,Arguments,IndexedVariablesBody,Vars),
		chr_none_locked(Vars,NoneLocked),
		if_used_state(Constraint,not_stored_yet,
					  ( State == not_stored_yet ->
						  ArgumentsGoal,
						    IndexedVariablesBody,
					            NoneLocked,
						    StoreYes
						;
						    % Vars = [],
						    StoreNo
						),
				% (Vars = [],StoreNo),StoreVarsGoal)
				StoreNo,StoreVarsGoal)
	),
	Body =
	(
		GetState,
		GetStateValue,
		UpdateState,
		GenerationHandling,
		StoreVarsGoal
	).
%~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
% allocate_constraint/4

generate_allocate_clauses([],List,List).
generate_allocate_clauses([C|Cs],List,Tail) :-
	generate_allocate_clause(C,List,List1),
	generate_allocate_clauses(Cs,List1,Tail).

allocate_constraint_goal(Constraint,Susp,Args,Goal) :-
	uses_state(Constraint,not_stored_yet),
	( chr_pp_flag(inline_insertremove,off) ->
		use_auxiliary_predicate(allocate_constraint,Constraint),
		allocate_constraint_atom(Constraint,Susp,Args,Goal)
	;
		Goal = (Susp = Suspension, Goal0),
		delay_phase_end(validate_store_type_assumptions,
			allocate_constraint_body(Constraint,Suspension,Args,Goal0)
		)
	).

allocate_constraint_atom(Constraint, Susp, Args,Goal) :-
	make_name('$allocate_constraint_',Constraint,Name),
	Goal =.. [Name,Susp|Args].

generate_allocate_clause(Constraint,List,Tail) :-
	( is_used_auxiliary_predicate(allocate_constraint,Constraint) ->
		List = [Clause|Tail],
		Clause = (Head :- Body),
		Constraint = _/A,
		length(Args,A),
		allocate_constraint_atom(Constraint,Susp,Args,Head),
		allocate_constraint_body(Constraint,Susp,Args,Body)
	;
		List = Tail
	).

allocate_constraint_body(Constraint,Susp,Args,Body) :-
	static_suspension_term(Constraint,Suspension),
	get_static_suspension_term_field(arguments,Constraint,Suspension,Args),
	( chr_pp_flag(debugable,on) ->
		Constraint = Functor / _,
		get_static_suspension_term_field(functor,Constraint,Suspension,Functor)
	;
		true
	),
	( chr_pp_flag(debugable,on) ->
		( may_trigger(Constraint) ->
			append(Args,[Susp],VarsSusp),
			build_head(F,A,[0],VarsSusp, ContinuationGoal),
			get_target_module(Mod),
			Continuation = Mod : ContinuationGoal
		;
			Continuation = true
		),
		Init = (Susp = Suspension),
		create_static_suspension_field(Constraint,Suspension,continuation,Continuation,CreateContinuation),
		create_static_suspension_field(Constraint,Suspension,generation,0,CreateGeneration)
	; may_trigger(Constraint), uses_field(Constraint,generation) ->
		create_static_suspension_field(Constraint,Suspension,generation,0,CreateGeneration),
		Susp = Suspension, Init = true, CreateContinuation = true
	;
		CreateGeneration = true, Susp = Suspension, Init = true, CreateContinuation = true
	),
	( uses_history(Constraint) ->
		create_static_suspension_field(Constraint,Suspension,history,t,CreateHistory)
	;
		CreateHistory = true
	),
	create_static_suspension_field(Constraint,Suspension,state,not_stored_yet,CreateState),
	( has_suspension_field(Constraint,id) ->
		get_static_suspension_term_field(id,Constraint,Suspension,Id),
		gen_id(Id,GenID)
	;
		GenID = true
	),
	Body =
	(
		Init,
		CreateContinuation,
		CreateGeneration,
		CreateHistory,
		CreateState,
		GenID
	).

gen_id(Id,'chr gen_id'(Id)).
%~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
% insert_constraint_internal

generate_insert_constraint_internal_clauses([],List,List).
generate_insert_constraint_internal_clauses([C|Cs],List,Tail) :-
	generate_insert_constraint_internal_clause(C,List,List1),
	generate_insert_constraint_internal_clauses(Cs,List1,Tail).

insert_constraint_internal_constraint_goal(Constraint, Vars, Suspension, Continuation, Args,Goal) :-
	( chr_pp_flag(inline_insertremove,off) ->
		use_auxiliary_predicate(remove_constraint_internal,Constraint),
		insert_constraint_internal_constraint_atom(Constraint,Vars,Suspension,Continuation,Args,Goal)
	;
		delay_phase_end(validate_store_type_assumptions,
			generate_insert_constraint_internal_body(Constraint,Suspension,Continuation,Args,Vars,Goal)
		)
	).


insert_constraint_internal_constraint_atom(Constraint,Vars,Self,Closure,Args,Goal) :-
	insert_constraint_internal_constraint_name(Constraint,Name),
	( chr_pp_flag(debugable,on) ->
		Goal =.. [Name, Vars, Self, Closure | Args]
	; ( only_ground_indexed_arguments(Constraint) ; get_store_type(Constraint,var_assoc_store(_,_)))->
		Goal =.. [Name,Self | Args]
	;
		Goal =.. [Name,Vars, Self | Args]
	).

insert_constraint_internal_constraint_name(Constraint,Name) :-
	make_name('$insert_constraint_internal_',Constraint,Name).

generate_insert_constraint_internal_clause(Constraint,List,Tail) :-
	( is_used_auxiliary_predicate(insert_constraint_internal,Constraint) ->
		List = [Clause|Tail],
		Clause = (Head :- Body),
		Constraint = _/A,
		length(Args,A),
		insert_constraint_internal_constraint_atom(Constraint, Vars, Suspension, Continuation,Args,Head),
		generate_insert_constraint_internal_body(Constraint,Suspension,Continuation,Args,Vars,Body)
	;
		List = Tail
	).


generate_insert_constraint_internal_body(Constraint,Susp,Continuation,Args,Vars,Body) :-
	static_suspension_term(Constraint,Suspension),
	create_static_suspension_field(Constraint,Suspension,state,active,CreateState),
	( chr_pp_flag(debugable,on) ->
		get_static_suspension_term_field(continuation,Constraint,Suspension,Continuation),
		create_static_suspension_field(Constraint,Suspension,generation,0,CreateGeneration)
	; may_trigger(Constraint), uses_field(Constraint,generation) ->
		create_static_suspension_field(Constraint,Suspension,generation,0,CreateGeneration)
	;
		CreateGeneration = true
	),
	( chr_pp_flag(debugable,on) ->
		Constraint = Functor / _,
		get_static_suspension_term_field(functor,Constraint,Suspension,Functor)
	;
		true
	),
	( uses_history(Constraint) ->
		create_static_suspension_field(Constraint,Suspension,history,t,CreateHistory)
	;
		CreateHistory = true
	),
	get_static_suspension_term_field(arguments,Constraint,Suspension,Args),
	List = [Clause|Tail],
	( chr_pp_flag(debugable,off), ( only_ground_indexed_arguments(Constraint) ; get_store_type(Constraint,var_assoc_store(_,_)))->
		suspension_term_base_fields(Constraint,BaseFields),
		( has_suspension_field(Constraint,id) ->
			get_static_suspension_term_field(id,Constraint,Suspension,Id),
			gen_id(Id,GenID)
		;
			GenID = true
		),
		Body =
		    (
			Susp = Suspension,
			CreateState,
		        CreateGeneration,
			CreateHistory,
			GenID
		    )
	;
		( has_suspension_field(Constraint,id) ->
			get_static_suspension_term_field(id,Constraint,Suspension,Id),
			gen_id(Id,GenID)
		;
			GenID = true
		),
		generate_indexed_variables_body(Constraint,Args,IndexedVariablesBody,Vars),
		chr_none_locked(Vars,NoneLocked),
		Body =
		(
			Susp = Suspension,
			IndexedVariablesBody,
			NoneLocked,
			CreateState,
			CreateGeneration,
			CreateHistory,
			GenID
		)
	).

%~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
% novel_production/2

generate_novel_production(List,Tail) :-
	( is_used_auxiliary_predicate(novel_production) ->
		List = [Clause|Tail],
		Clause =
		(
			'$novel_production'( Self, Tuple) :-
				% arg( 3, Self, Ref), % ARGXXX
				% 'chr get_mutable'( History, Ref),
				arg( 3, Self, History), % ARGXXX
				( hprolog:get_ds( Tuple, History, _) ->
					fail
				;
					true
				)
		)
	;
		List = Tail
	).

%~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
% extend_history/2

generate_extend_history(List,Tail) :-
	( is_used_auxiliary_predicate(extend_history) ->
		List = [Clause|Tail],
		Clause =
		(
			'$extend_history'( Self, Tuple) :-
				% arg( 3, Self, Ref), % ARGXXX
				% 'chr get_mutable'( History, Ref),
				arg( 3, Self, History), % ARGXXX
				hprolog:put_ds( Tuple, History, x, NewHistory),
				setarg( 3, Self, NewHistory) % ARGXXX
		)
	;
		List = Tail
	).

%~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
%
:- chr_constraint
	empty_named_history_initialisations/2,
	generate_empty_named_history_initialisation/1,
	find_empty_named_histories/0.

generate_empty_named_history_initialisations(List, Tail) :-
	empty_named_history_initialisations(List, Tail),
	find_empty_named_histories.

find_empty_named_histories, history(_, Name, []) ==>
	generate_empty_named_history_initialisation(Name).

generate_empty_named_history_initialisation(Name) \
	generate_empty_named_history_initialisation(Name) <=> true.
generate_empty_named_history_initialisation(Name) \
	empty_named_history_initialisations(List, Tail) # Passive
  <=>
	empty_named_history_global_variable(Name, GlobalVariable),
	List = [(:- nb_setval(GlobalVariable, 0))|Rest],
	empty_named_history_initialisations(Rest, Tail)
  pragma passive(Passive).

find_empty_named_histories \
	generate_empty_named_history_initialisation(_) # Passive <=> true
pragma passive(Passive).

find_empty_named_histories,
	empty_named_history_initialisations(List, Tail) # Passive <=> List = Tail
pragma passive(Passive).

find_empty_named_histories <=>
	chr_error(internal, 'find_empty_named_histories was not removed', []).


empty_named_history_global_variable(Name, GlobalVariable) :-
	atom_concat('chr empty named history ', Name, GlobalVariable).

empty_named_history_novel_production(Name, nb_getval(GlobalVariable, 0)) :-
	empty_named_history_global_variable(Name, GlobalVariable).

empty_named_history_extend_history(Name, b_setval(GlobalVariable, 1)) :-
	empty_named_history_global_variable(Name, GlobalVariable).


%~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
% run_suspensions/2

generate_run_suspensions_clauses([],List,List).
generate_run_suspensions_clauses([C|Cs],List,Tail) :-
	generate_run_suspensions_clause(C,List,List1),
	generate_run_suspensions_clauses(Cs,List1,Tail).

run_suspensions_goal(Constraint,Suspensions,Goal) :-
	make_name('$run_suspensions_',Constraint,Name),
	Goal =.. [Name,Suspensions].

generate_run_suspensions_clause(Constraint,List,Tail) :-
	( is_used_auxiliary_predicate(run_suspensions,Constraint) ->
		List = [Clause1,Clause2|Tail],
		run_suspensions_goal(Constraint,[],Clause1),
		( chr_pp_flag(debugable,on) ->
			run_suspensions_goal(Constraint,[Suspension|Suspensions],Clause2Head),
			get_update_suspension_field(Constraint,Suspension,state,State,triggered,GetState,GetStateValue,UpdateState),
			get_update_suspension_field(Constraint,Suspension,state,Post,active,GetPost,GetPostValue,UpdatePost),
			get_update_suspension_field(Constraint,Suspension,generation,Gen,Generation,GetGeneration,GetGenerationValue,UpdateGeneration),
			get_dynamic_suspension_term_field(continuation,Constraint,Suspension,Continuation,GetContinuation),
			run_suspensions_goal(Constraint,Suspensions,Clause2Recursion),
			Clause2 =
			(
				Clause2Head :-
					GetState,
					GetStateValue,
					( State==active ->
					    UpdateState,
					    GetGeneration,
					    GetGenerationValue,
					    Generation is Gen+1,
					    UpdateGeneration,
					    GetContinuation,
					    (
						'chr debug_event'(wake(Suspension)),
					        call(Continuation)
					    ;
						'chr debug_event'(fail(Suspension)), !,
						fail
					    ),
					    (
						'chr debug_event'(exit(Suspension))
					    ;
						'chr debug_event'(redo(Suspension)),
						fail
					    ),
					    GetPost,
					    GetPostValue,
					    ( Post==triggered ->
						UpdatePost   % catching constraints that did not do anything
					    ;
						true
					    )
					;
					    true
					),
					Clause2Recursion
			)
		;
			run_suspensions_goal(Constraint,[Suspension|Suspensions],Clause2Head),
			static_suspension_term(Constraint,SuspensionTerm),
			get_static_suspension_term_field(arguments,Constraint,SuspensionTerm,Arguments),
			append(Arguments,[Suspension],VarsSusp),
			make_suspension_continuation_goal(Constraint,VarsSusp,Continuation),
			run_suspensions_goal(Constraint,Suspensions,Clause2Recursion),
			( uses_field(Constraint,generation) ->
				get_update_static_suspension_field(Constraint,Suspension,SuspensionTerm,generation,Gen,Generation,GetGeneration,UpdateGeneration),
				GenerationHandling = ( GetGeneration, Generation is Gen+1, UpdateGeneration)
			;
				GenerationHandling = true
			),
			get_update_static_suspension_field(Constraint,Suspension,SuspensionTerm,state,State,triggered,GetState,UpdateState),
			get_update_static_suspension_field(Constraint,Suspension,SuspensionTerm,state,Post,active,GetPostState,UpdatePostState),
			if_used_state(Constraint,removed,
				( GetState,
					( State==active
					-> ReactivateConstraint
					;  true)
				),ReactivateConstraint,CondReactivate),
			ReactivateConstraint =
			(
				UpdateState,
				GenerationHandling,
				Continuation,
				GetPostState,
				( Post==triggered ->
				    UpdatePostState	% catching constraints that did not do anything
				;
				    true
				)
			),
			Clause2 =
			(
				Clause2Head :-
					Suspension = SuspensionTerm,
					CondReactivate,
					Clause2Recursion
			)
		)
	;
		List = Tail
	).

%~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
generate_attach_increment(Clauses) :-
	get_max_constraint_index(N),
	( is_used_auxiliary_predicate(attach_increment), N > 0 ->
		Clauses = [Clause1,Clause2],
		generate_attach_increment_empty(Clause1),
		( N == 1 ->
			generate_attach_increment_one(Clause2)
		;
			generate_attach_increment_many(N,Clause2)
		)
	;
		Clauses = []
	).

generate_attach_increment_empty((attach_increment([],_) :- true)).

generate_attach_increment_one(Clause) :-
	Head = attach_increment([Var|Vars],Susps),
	get_target_module(Mod),
	chr_not_locked(Var,NotLocked),
	Body =
	(
		NotLocked,
		( get_attr(Var,Mod,VarSusps) ->
			sort(VarSusps,SortedVarSusps),
			'chr merge_attributes'(Susps,SortedVarSusps,MergedSusps),
			put_attr(Var,Mod,MergedSusps)
		;
			put_attr(Var,Mod,Susps)
		),
		attach_increment(Vars,Susps)
	),
	Clause = (Head :- Body).

generate_attach_increment_many(N,Clause) :-
	Head = attach_increment([Var|Vars],TAttr1),
	% writeln(merge_attributes_1_before),
	merge_attributes(N,TAttr1,TAttr2,MergeGoal,Attr),
	% writeln(merge_attributes_1_after),
	get_target_module(Mod),
	chr_not_locked(Var,NotLocked),
	Body =
	(
		NotLocked,
		( get_attr(Var,Mod,TAttr2) ->
			MergeGoal,
			put_attr(Var,Mod,Attr)
		;
			put_attr(Var,Mod,TAttr1)
		),
		attach_increment(Vars,TAttr1)
	),
	Clause = (Head :- Body).

%%	attr_unify_hook
generate_attr_unify_hook(Clauses) :-
	get_max_constraint_index(N),
	( N == 0 ->
		Clauses = []
	;
		Clauses = [GoalsClause|HookClauses],
		GoalsClause = attribute_goals(_,Goals,Goals),
		( N == 1 ->
			generate_attr_unify_hook_one(HookClauses)
		;
			generate_attr_unify_hook_many(N,HookClauses)
		)
	).

generate_attr_unify_hook_one([Clause]) :-
	Head = attr_unify_hook(Susps,Other),
	get_target_module(Mod),
	get_indexed_constraint(1,C),
	( get_store_type(C,ST),
	  ( ST = default ; ST = multi_store(STs), memberchk(default,STs) ) ->
		make_run_suspensions(NewSusps,SortedSusps,WakeNewSusps),
		make_run_suspensions(SortedSusps,SortedSusps,WakeSusps),
		( atomic_types_suspended_constraint(C) ->
			SortGoal1   = true,
			SortedSusps = Susps,
			SortGoal2   = true,
			SortedOtherSusps = OtherSusps,
			MergeGoal = (append(Susps,OtherSusps,List), sort(List,NewSusps)),
			NonvarBody = true
		;
			SortGoal1 = sort(Susps, SortedSusps),
			SortGoal2 = sort(OtherSusps,SortedOtherSusps),
			MergeGoal = 'chr merge_attributes'(SortedSusps,SortedOtherSusps,NewSusps),
			use_auxiliary_predicate(attach_increment),
			NonvarBody =
				( compound(Other) ->
					term_variables(Other,OtherVars),
					attach_increment(OtherVars, SortedSusps)
				;
					true
				)
		),
		Body =
		(
			SortGoal1,
			( var(Other) ->
				( get_attr(Other,Mod,OtherSusps) ->
					SortGoal2,
					MergeGoal,
					put_attr(Other,Mod,NewSusps),
					WakeNewSusps
				;
					put_attr(Other,Mod,SortedSusps),
					WakeSusps
				)
			;
				NonvarBody,
				WakeSusps
			)
		),
		Clause = (Head :- Body)
	; get_store_type(C,var_assoc_store(VarIndex,KeyIndex)) ->
		make_run_suspensions(List,List,WakeNewSusps),
		MergeGoal = (merge_into_assoc_store(Susps,OtherSusps,List)),
		Body =
			( get_attr(Other,Mod,OtherSusps) ->
				MergeGoal,
				WakeNewSusps
			;
				put_attr(Other,Mod,Susps)
			),
		Clause = (Head :- Body)
	).


generate_attr_unify_hook_many(N,[Clause]) :-
	chr_pp_flag(dynattr,off), !,
	Head = attr_unify_hook(Attr,Other),
	get_target_module(Mod),
	make_attr(N,Mask,SuspsList,Attr),
	bagof(Sort,A ^ B ^ ( member(A,SuspsList) , Sort = sort(A,B) ) , SortGoalList),
	list2conj(SortGoalList,SortGoals),
	bagof(B, A ^ member(sort(A,B),SortGoalList), SortedSuspsList),
	merge_attributes2(N,Mask,SortedSuspsList,TOtherAttr,MergeGoal,MergedAttr),
	get_all_suspensions2(N,MergedAttr,MergedSuspsList),
	make_attr(N,Mask,SortedSuspsList,SortedAttr),
	make_run_suspensions_loop(MergedSuspsList,SortedSuspsList,WakeMergedSusps),
	make_run_suspensions_loop(SortedSuspsList,SortedSuspsList,WakeSortedSusps),
	( forall((between(1,N,Index), get_indexed_constraint(Index,Constraint)),atomic_types_suspended_constraint(Constraint)) ->
		NonvarBody = true
	;
		use_auxiliary_predicate(attach_increment),
		NonvarBody =
			( compound(Other) ->
				term_variables(Other,OtherVars),
				attach_increment(OtherVars,SortedAttr)
			;
				true
			)
	),
	Body =
	(
		SortGoals,
		( var(Other) ->
			( get_attr(Other,Mod,TOtherAttr) ->
				MergeGoal,
				put_attr(Other,Mod,MergedAttr),
				WakeMergedSusps
			;
				put_attr(Other,Mod,SortedAttr),
				WakeSortedSusps
			)
		;
			NonvarBody,
			WakeSortedSusps
		)
	),
	Clause = (Head :- Body).

% NEW
generate_attr_unify_hook_many(N,Clauses) :-
	Head = attr_unify_hook(Attr,Other),
	get_target_module(Mod),
	normalize_attr(Attr,NormalGoal,NormalAttr),
	normalize_attr(OtherAttr,NormalOtherGoal,NormalOtherAttr),
	merge_attributes(N,NormalAttr,NormalOtherAttr,MergeGoal,MergedAttr),
	make_run_suspensions(N),
	( forall((between(1,N,Index), get_indexed_constraint(Index,Constraint)),atomic_types_suspended_constraint(Constraint)) ->
		NonvarBody = true
	;
		use_auxiliary_predicate(attach_increment),
		NonvarBody =
			( compound(Other) ->
				term_variables(Other,OtherVars),
				attach_increment(OtherVars,NormalAttr)
			;
				true
			)
	),
	Body =
	(
		NormalGoal,
		( var(Other) ->
			( get_attr(Other,Mod,OtherAttr) ->
				NormalOtherGoal,
				MergeGoal,
				put_attr(Other,Mod,MergedAttr),
				'$dispatch_run_suspensions'(MergedAttr)
			;
				put_attr(Other,Mod,NormalAttr),
				'$dispatch_run_suspensions'(NormalAttr)
			)
		;
			NonvarBody,
			'$dispatch_run_suspensions'(NormalAttr)
		)
	),
	Clause = (Head :- Body),
	Clauses = [Clause,DispatchList1,DispatchList2|Dispatchers],
	DispatchList1 = ('$dispatch_run_suspensions'([])),
	DispatchList2 = ('$dispatch_run_suspensions'([Pos-List|Rest]) :- '$dispatch_run_suspensions'(Pos,List),'$dispatch_run_suspensions'(Rest)),
	run_suspensions_dispatchers(N,[],Dispatchers).

% NEW
run_suspensions_dispatchers(N,Acc,Dispatchers) :-
	( N > 0 ->
		get_indexed_constraint(N,C),
		NAcc = [('$dispatch_run_suspensions'(N,List) :- Body)|Acc],
		( may_trigger(C) ->
			run_suspensions_goal(C,List,Body)
		;
			Body = true
		),
		M is N - 1,
		run_suspensions_dispatchers(M,NAcc,Dispatchers)
	;
		Dispatchers = Acc
	).

% NEW
make_run_suspensions(N) :-
	( N > 0 ->
		( get_indexed_constraint(N,C),
		  may_trigger(C) ->
			use_auxiliary_predicate(run_suspensions,C)
		;
			true
		),
		M is N - 1,
		make_run_suspensions(M)
	;
		true
	).

make_run_suspensions(AllSusps,OneSusps,Goal) :-
	make_run_suspensions(1,AllSusps,OneSusps,Goal).

make_run_suspensions(Index,AllSusps,OneSusps,Goal) :-
	( get_indexed_constraint(Index,C), may_trigger(C) ->
		use_auxiliary_predicate(run_suspensions,C),
		( wakes_partially(C) ->
			run_suspensions_goal(C,OneSusps,Goal)
		;
			run_suspensions_goal(C,AllSusps,Goal)
		)
	;
		Goal = true
	).

make_run_suspensions_loop(AllSuspsList,OneSuspsList,Goal) :-
	make_run_suspensions_loop(AllSuspsList,OneSuspsList,1,Goal).

make_run_suspensions_loop([],[],_,true).
make_run_suspensions_loop([AllSusps|AllSuspsList],[OneSusps|OneSuspsList],I,(Goal,Goals)) :-
	make_run_suspensions(I,AllSusps,OneSusps,Goal),
	J is I + 1,
	make_run_suspensions_loop(AllSuspsList,OneSuspsList,J,Goals).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% $insert_in_store_F/A
% $delete_from_store_F/A

generate_insert_delete_constraints([],[]).
generate_insert_delete_constraints([FA|Rest],Clauses) :-
	( is_stored(FA) ->
		generate_insert_delete_constraint(FA,Clauses,RestClauses)
	;
		Clauses = RestClauses
	),
	generate_insert_delete_constraints(Rest,RestClauses).

generate_insert_delete_constraint(FA,Clauses,RestClauses) :-
	insert_constraint_clause(FA,Clauses,RestClauses1),
	delete_constraint_clause(FA,RestClauses1,RestClauses).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
% insert_in_store

insert_constraint_goal(FA,Susp,Vars,Goal) :-
	( chr_pp_flag(inline_insertremove,off) ->
		use_auxiliary_predicate(insert_in_store,FA),
		insert_constraint_atom(FA,Susp,Goal)
	;
		delay_phase_end(validate_store_type_assumptions,
			( insert_constraint_body(FA,Susp,UsedVars,Goal),
			  insert_constraint_direct_used_vars(UsedVars,Vars)
		        )
		)
	).

insert_constraint_direct_used_vars([],_).
insert_constraint_direct_used_vars([Index-Var|Rest],Vars) :-
	nth1(Index,Vars,Var),
	insert_constraint_direct_used_vars(Rest,Vars).

insert_constraint_atom(FA,Susp,Call) :-
	make_name('$insert_in_store_',FA,Functor),
	Call =.. [Functor,Susp].

insert_constraint_clause(C,Clauses,RestClauses) :-
	( is_used_auxiliary_predicate(insert_in_store,C) ->
		Clauses = [Clause|RestClauses],
		Clause = (Head :- InsertCounterInc,VarsBody,Body),
		insert_constraint_atom(C,Susp,Head),
		insert_constraint_body(C,Susp,UsedVars,Body),
		insert_constraint_used_vars(UsedVars,C,Susp,VarsBody),
		( chr_pp_flag(store_counter,on) ->
			InsertCounterInc = '$insert_counter_inc'
		;
			InsertCounterInc = true
		)
	;
		Clauses = RestClauses
	).

insert_constraint_used_vars([],_,_,true).
insert_constraint_used_vars([Index-Var|Rest],C,Susp,(Goal,Goals)) :-
	get_dynamic_suspension_term_field(argument(Index),C,Susp,Var,Goal),
	insert_constraint_used_vars(Rest,C,Susp,Goals).

insert_constraint_body(C,Susp,UsedVars,Body) :-
	get_store_type(C,StoreType),
	insert_constraint_body(StoreType,C,Susp,UsedVars,Body).

insert_constraint_body(default,C,Susp,[],Body) :-
	global_list_store_name(C,StoreName),
	make_get_store_goal(StoreName,Store,GetStoreGoal),
	make_update_store_goal(StoreName,Cell,UpdateStoreGoal),
	( chr_pp_flag(debugable,on) ->
		Cell = [Susp|Store],
		Body =
		(
			GetStoreGoal,
			UpdateStoreGoal
		)
	;
		set_dynamic_suspension_term_field(global_list_prev,C,NextSusp,Cell,SetGoal),
		Body =
		(
			GetStoreGoal,
			Cell = [Susp|Store],
			UpdateStoreGoal,
			( Store = [NextSusp|_] ->
				SetGoal
			;
				true
			)
		)
	).
%	get_target_module(Mod),
%	get_max_constraint_index(Total),
%	( Total == 1 ->
%		generate_attach_body_1(C,Store,Susp,AttachBody)
%	;
%		generate_attach_body_n(C,Store,Susp,AttachBody)
%	),
%	Body =
%	(
%		'chr default_store'(Store),
%		AttachBody
%	).
insert_constraint_body(multi_inthash(Indexes),C,Susp,[],Body) :-
	generate_multi_inthash_insert_constraint_bodies(Indexes,C,Susp,Body).
insert_constraint_body(multi_hash(Indexes),C,Susp,MixedUsedVars,Body) :-
	generate_multi_hash_insert_constraint_bodies(Indexes,C,Susp,Body,MixedUsedVars),
	sort_out_used_vars(MixedUsedVars,UsedVars).
insert_constraint_body(atomic_constants(Index,_,_),C,Susp,UsedVars,Body) :-
	multi_hash_key_direct(C,Index,Susp,Key,UsedVars),
	constants_store_index_name(C,Index,IndexName),
	IndexLookup =.. [IndexName,Key,StoreName],
	Body =
	( IndexLookup ->
		nb_getval(StoreName,Store),
		b_setval(StoreName,[Susp|Store])
	;
		true
	).
insert_constraint_body(ground_constants(Index,_,_),C,Susp,UsedVars,Body) :-
	multi_hash_key_direct(C,Index,Susp,Key,UsedVars),
	constants_store_index_name(C,Index,IndexName),
	IndexLookup =.. [IndexName,Key,StoreName],
	Body =
	( IndexLookup ->
		nb_getval(StoreName,Store),
		b_setval(StoreName,[Susp|Store])
	;
		true
	).
insert_constraint_body(global_ground,C,Susp,[],Body) :-
	global_ground_store_name(C,StoreName),
	make_get_store_goal(StoreName,Store,GetStoreGoal),
	make_update_store_goal(StoreName,Cell,UpdateStoreGoal),
	( chr_pp_flag(debugable,on) ->
		Cell = [Susp|Store],
		Body =
		(
			GetStoreGoal,
			UpdateStoreGoal
		)
	;
		set_dynamic_suspension_term_field(global_list_prev,C,NextSusp,Cell,SetGoal),
		Body =
		(
			GetStoreGoal,
			Cell = [Susp|Store],
			UpdateStoreGoal,
			( Store = [NextSusp|_] ->
				SetGoal
			;
				true
			)
		)
	).
%	global_ground_store_name(C,StoreName),
%	make_get_store_goal(StoreName,Store,GetStoreGoal),
%	make_update_store_goal(StoreName,[Susp|Store],UpdateStoreGoal),
%	Body =
%	(
%		GetStoreGoal,    % nb_getval(StoreName,Store),
%		UpdateStoreGoal  % b_setval(StoreName,[Susp|Store])
%	).
insert_constraint_body(var_assoc_store(VarIndex,AssocIndex),C,Susp,[VarIndex-Variable,AssocIndex-Key],Body) :-
	% TODO: generalize to more than one !!!
	get_target_module(Module),
	Body = ( get_attr(Variable,Module,AssocStore) ->
			insert_assoc_store(AssocStore,Key,Susp)
		;
			new_assoc_store(AssocStore),
			put_attr(Variable,Module,AssocStore),
			insert_assoc_store(AssocStore,Key,Susp)
		).

insert_constraint_body(global_singleton,C,Susp,[],Body) :-
	global_singleton_store_name(C,StoreName),
	make_update_store_goal(StoreName,Susp,UpdateStoreGoal),
	Body =
	(
		UpdateStoreGoal
	).
insert_constraint_body(multi_store(StoreTypes),C,Susp,UsedVars,Body) :-
	maplist(insert_constraint_body1(C,Susp),StoreTypes,NestedUsedVars,Bodies),
	list2conj(Bodies,Body),
	sort_out_used_vars(NestedUsedVars,UsedVars).
insert_constraint_body1(C,Susp,StoreType,UsedVars,Body) :-
	insert_constraint_body(StoreType,C,Susp,UsedVars,Body).
insert_constraint_body(identifier_store(Index),C,Susp,UsedVars,Body) :-
	UsedVars = [Index-Var],
	get_identifier_size(ISize),
	functor(Struct,struct,ISize),
	get_identifier_index(C,Index,IIndex),
	arg(IIndex,Struct,Susps),
	Body = (Var = Struct, setarg(IIndex,Var,[Susp|Susps])).
insert_constraint_body(type_indexed_identifier_store(Index,IndexType),C,Susp,UsedVars,Body) :-
	UsedVars = [Index-Var],
	type_indexed_identifier_structure(IndexType,Struct),
	get_type_indexed_identifier_index(IndexType,C,Index,IIndex),
	arg(IIndex,Struct,Susps),
	Body = (Var = Struct, setarg(IIndex,Var,[Susp|Susps])).

sort_out_used_vars(NestedUsedVars,UsedVars) :-
	flatten(NestedUsedVars,FlatUsedVars),
	sort(FlatUsedVars,SortedFlatUsedVars),
	sort_out_used_vars1(SortedFlatUsedVars,UsedVars).

sort_out_used_vars1([],[]).
sort_out_used_vars1([I-V],L) :- !, L = [I-V].
sort_out_used_vars1([I-X,J-Y|R],L) :-
	( I == J ->
		X = Y,
		sort_out_used_vars1([I-X|R],L)
	;
		L = [I-X|T],
		sort_out_used_vars1([J-Y|R],T)
	).

generate_multi_inthash_insert_constraint_bodies([],_,_,true).
generate_multi_inthash_insert_constraint_bodies([Index|Indexes],FA,Susp,(Body,Bodies)) :-
	multi_hash_store_name(FA,Index,StoreName),
	multi_hash_key(FA,Index,Susp,KeyBody,Key),
	Body =
	(
		KeyBody,
		nb_getval(StoreName,Store),
		insert_iht(Store,Key,Susp)
	),
	generate_multi_inthash_insert_constraint_bodies(Indexes,FA,Susp,Bodies).

generate_multi_hash_insert_constraint_bodies([],_,_,true,[]).
generate_multi_hash_insert_constraint_bodies([Index|Indexes],FA,Susp,(Body,Bodies),[UsedVars|MoreUsedVars]) :-
	multi_hash_store_name(FA,Index,StoreName),
	multi_hash_key_direct(FA,Index,Susp,Key,UsedVars),
	make_get_store_goal(StoreName,Store,GetStoreGoal),
	(   chr_pp_flag(ht_removal,on)
	->  ht_prev_field(Index,PrevField),
	    set_dynamic_suspension_term_field(PrevField,FA,NextSusp,Result,
		SetGoal),
	    Body =
	    (
		GetStoreGoal,
		insert_ht(Store,Key,Susp,Result),
		(   Result = [_,NextSusp|_]
		->  SetGoal
		;   true
		)
	    )
	;   Body =
	    (
		GetStoreGoal,
		insert_ht(Store,Key,Susp)
	    )
	),
	generate_multi_hash_insert_constraint_bodies(Indexes,FA,Susp,Bodies,MoreUsedVars).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
% Delete

delete_constraint_clause(C,Clauses,RestClauses) :-
	( is_used_auxiliary_predicate(delete_from_store,C) ->
		Clauses = [Clause|RestClauses],
		Clause = (Head :- Body),
		delete_constraint_atom(C,Susp,Head),
		C = F/A,
		functor(Head,F,A),
		delete_constraint_body(C,Head,Susp,[],Body)
	;
		Clauses = RestClauses
	).

delete_constraint_goal(Head,Susp,VarDict,Goal) :-
	functor(Head,F,A),
	C = F/A,
	( chr_pp_flag(inline_insertremove,off) ->
		use_auxiliary_predicate(delete_from_store,C),
		delete_constraint_atom(C,Susp,Goal)
	;
		delay_phase_end(validate_store_type_assumptions, delete_constraint_body(C,Head,Susp,VarDict,Goal))
	).

delete_constraint_atom(C,Susp,Atom) :-
	make_name('$delete_from_store_',C,Functor),
	Atom =.. [Functor,Susp].


delete_constraint_body(C,Head,Susp,VarDict,Body) :-
	Body = (CounterBody,DeleteBody),
	( chr_pp_flag(store_counter,on) ->
		CounterBody = '$delete_counter_inc'
	;
		CounterBody = true
	),
	get_store_type(C,StoreType),
	delete_constraint_body(StoreType,C,Head,Susp,VarDict,DeleteBody).

delete_constraint_body(default,C,_,Susp,_,Body) :-
	( chr_pp_flag(debugable,on) ->
		global_list_store_name(C,StoreName),
		make_get_store_goal(StoreName,Store,GetStoreGoal),
		make_update_store_goal(StoreName,NStore,UpdateStoreGoal),
		Body =
		(
			GetStoreGoal, % nb_getval(StoreName,Store),
			'chr sbag_del_element'(Store,Susp,NStore),
			UpdateStoreGoal % b_setval(StoreName,NStore)
		)
	;
		get_dynamic_suspension_term_field(global_list_prev,C,Susp,PredCell,GetGoal),
		global_list_store_name(C,StoreName),
		make_get_store_goal(StoreName,Store,GetStoreGoal),
		make_update_store_goal(StoreName,Tail,UpdateStoreGoal),
		set_dynamic_suspension_term_field(global_list_prev,C,NextSusp,_,SetGoal1),
		set_dynamic_suspension_term_field(global_list_prev,C,NextSusp,PredCell,SetGoal2),
		Body =
		(
			GetGoal,
			( var(PredCell) ->
				GetStoreGoal, % nb_getval(StoreName,Store),
				Store = [_|Tail],
				UpdateStoreGoal,
				( Tail = [NextSusp|_] ->
					SetGoal1
				;
					true
				)
			;
				PredCell = [_,_|Tail],
				setarg(2,PredCell,Tail),
				( Tail = [NextSusp|_] ->
					SetGoal2
				;
					true
				)
			)
		)
	).
%	get_target_module(Mod),
%	get_max_constraint_index(Total),
%	( Total == 1 ->
%		generate_detach_body_1(C,Store,Susp,DetachBody),
%		Body =
%		(
%			'chr default_store'(Store),
%			DetachBody
%		)
%	;
%		generate_detach_body_n(C,Store,Susp,DetachBody),
%		Body =
%		(
%			'chr default_store'(Store),
%			DetachBody
%		)
%	).
delete_constraint_body(multi_inthash(Indexes),C,_,Susp,_,Body) :-
	generate_multi_inthash_delete_constraint_bodies(Indexes,C,Susp,Body).
delete_constraint_body(multi_hash(Indexes),C,Head,Susp,VarDict,Body) :-
	generate_multi_hash_delete_constraint_bodies(Indexes,C,Head,Susp,VarDict,Body).
delete_constraint_body(atomic_constants(Index,_,_),C,Head,Susp,VarDict,Body) :-
	multi_hash_key(C,Head,Index,Susp,VarDict,KeyBody,Key),
	constants_store_index_name(C,Index,IndexName),
	IndexLookup =.. [IndexName,Key,StoreName],
	Body =
	( KeyBody,
	 ( IndexLookup ->
		nb_getval(StoreName,Store),
		'chr sbag_del_element'(Store,Susp,NStore),
		b_setval(StoreName,NStore)
	;
		true
	)).
delete_constraint_body(ground_constants(Index,_,_),C,Head,Susp,VarDict,Body) :-
	multi_hash_key(C,Head,Index,Susp,VarDict,KeyBody,Key),
	constants_store_index_name(C,Index,IndexName),
	IndexLookup =.. [IndexName,Key,StoreName],
	Body =
	( KeyBody,
	 ( IndexLookup ->
		nb_getval(StoreName,Store),
		'chr sbag_del_element'(Store,Susp,NStore),
		b_setval(StoreName,NStore)
	;
		true
	)).
delete_constraint_body(global_ground,C,_,Susp,_,Body) :-
	( chr_pp_flag(debugable,on) ->
		global_ground_store_name(C,StoreName),
		make_get_store_goal(StoreName,Store,GetStoreGoal),
		make_update_store_goal(StoreName,NStore,UpdateStoreGoal),
		Body =
		(
			GetStoreGoal, % nb_getval(StoreName,Store),
			'chr sbag_del_element'(Store,Susp,NStore),
			UpdateStoreGoal % b_setval(StoreName,NStore)
		)
	;
		get_dynamic_suspension_term_field(global_list_prev,C,Susp,PredCell,GetGoal),
		global_ground_store_name(C,StoreName),
		make_get_store_goal(StoreName,Store,GetStoreGoal),
		make_update_store_goal(StoreName,Tail,UpdateStoreGoal),
		set_dynamic_suspension_term_field(global_list_prev,C,NextSusp,_,SetGoal1),
		set_dynamic_suspension_term_field(global_list_prev,C,NextSusp,PredCell,SetGoal2),
		Body =
		(
			GetGoal,
			( var(PredCell) ->
				GetStoreGoal, % nb_getval(StoreName,Store),
				Store = [_|Tail],
				UpdateStoreGoal,
				( Tail = [NextSusp|_] ->
					SetGoal1
				;
					true
				)
			;
				PredCell = [_,_|Tail],
				setarg(2,PredCell,Tail),
				( Tail = [NextSusp|_] ->
					SetGoal2
				;
					true
				)
			)
		)
	).
%	global_ground_store_name(C,StoreName),
%	make_get_store_goal(StoreName,Store,GetStoreGoal),
%	make_update_store_goal(StoreName,NStore,UpdateStoreGoal),
%	Body =
%	(
%		GetStoreGoal, % nb_getval(StoreName,Store),
%		'chr sbag_del_element'(Store,Susp,NStore),
%		UpdateStoreGoal % b_setval(StoreName,NStore)
%	).
delete_constraint_body(var_assoc_store(VarIndex,AssocIndex),C,_,Susp,_,Body) :-
	get_target_module(Module),
	get_dynamic_suspension_term_field(argument(VarIndex),C,Susp,Variable,VariableGoal),
	get_dynamic_suspension_term_field(argument(AssocIndex),C,Susp,Key,KeyGoal),
	Body = (
		VariableGoal,
		get_attr(Variable,Module,AssocStore),
		KeyGoal,
		delete_assoc_store(AssocStore,Key,Susp)
	).
delete_constraint_body(global_singleton,C,_,_Susp,_,Body) :-
	global_singleton_store_name(C,StoreName),
	make_update_store_goal(StoreName,[],UpdateStoreGoal),
	Body =
	(
		UpdateStoreGoal  % b_setval(StoreName,[])
	).
delete_constraint_body(multi_store(StoreTypes),C,Head,Susp,VarDict,Body) :-
	maplist(delete_constraint_body1(C,Head,Susp,VarDict),StoreTypes,Bodies),
	list2conj(Bodies,Body).
delete_constraint_body1(C,Head,Susp,VarDict,StoreType,Body) :-
	delete_constraint_body(StoreType,C,Head,Susp,VarDict,Body).
delete_constraint_body(identifier_store(Index),C,Head,Susp,VarDict,Body) :-
	get_suspension_argument_possibly_in_scope(Head,VarDict,Susp,Index,Variable,VariableGoal),
	get_identifier_size(ISize),
	functor(Struct,struct,ISize),
	get_identifier_index(C,Index,IIndex),
	arg(IIndex,Struct,Susps),
	Body = (
		VariableGoal,
		Variable = Struct,
		'chr sbag_del_element'(Susps,Susp,NSusps),
		setarg(IIndex,Variable,NSusps)
	).
delete_constraint_body(type_indexed_identifier_store(Index,IndexType),C,Head,Susp,VarDict,Body) :-
	get_suspension_argument_possibly_in_scope(Head,VarDict,Susp,Index,Variable,VariableGoal),
	type_indexed_identifier_structure(IndexType,Struct),
	get_type_indexed_identifier_index(IndexType,C,Index,IIndex),
	arg(IIndex,Struct,Susps),
	Body = (
		VariableGoal,
		Variable = Struct,
		'chr sbag_del_element'(Susps,Susp,NSusps),
		setarg(IIndex,Variable,NSusps)
	).

generate_multi_inthash_delete_constraint_bodies([],_,_,true).
generate_multi_inthash_delete_constraint_bodies([Index|Indexes],FA,Susp,(Body,Bodies)) :-
	multi_hash_store_name(FA,Index,StoreName),
	multi_hash_key(FA,Index,Susp,KeyBody,Key),
	Body =
	(
		KeyBody,
		nb_getval(StoreName,Store),
		delete_iht(Store,Key,Susp)
	),
	generate_multi_inthash_delete_constraint_bodies(Indexes,FA,Susp,Bodies).
generate_multi_hash_delete_constraint_bodies([],_,_,_,_,true).
generate_multi_hash_delete_constraint_bodies([Index|Indexes],C,Head,Susp,VarDict,(Body,Bodies)) :-
	multi_hash_store_name(C,Index,StoreName),
	multi_hash_key(C,Head,Index,Susp,VarDict,KeyBody,Key),
	make_get_store_goal(StoreName,Store,GetStoreGoal),
	(   chr_pp_flag(ht_removal,on)
	->  ht_prev_field(Index,PrevField),
	    get_dynamic_suspension_term_field(PrevField,C,Susp,Prev,GetGoal),
	    set_dynamic_suspension_term_field(PrevField,C,NextSusp,_,
		SetGoal1),
	    set_dynamic_suspension_term_field(PrevField,C,NextSusp,Prev,
		SetGoal2),
	    Body =
	    (
		GetGoal,
		(   var(Prev)
		->  GetStoreGoal,
		    KeyBody,
		    delete_first_ht(Store,Key,Values),
		    (   Values = [NextSusp|_]
		    ->  SetGoal1
		    ;   true
		    )
		;   Prev = [_,_|Values],
		    setarg(2,Prev,Values),
		    (   Values = [NextSusp|_]
		    ->  SetGoal2
		    ;   true
		    )
		)
	    )
	;   Body =
	    (
		KeyBody,
		GetStoreGoal, % nb_getval(StoreName,Store),
		delete_ht(Store,Key,Susp)
	    )
	),
	generate_multi_hash_delete_constraint_bodies(Indexes,FA,Head,Susp,VarDict,Bodies).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

:- chr_constraint
	module_initializer/1,
	module_initializers/1.

module_initializers(G), module_initializer(Initializer) <=>
	G = (Initializer,Initializers),
	module_initializers(Initializers).

module_initializers(G) <=>
	G = true.

generate_attach_code(Constraints,Clauses) :-
	enumerate_stores_code(Constraints,Enumerate),
	append(Enumerate,L,Clauses),
	generate_attach_code(Constraints,L,T),
	module_initializers(Initializers),
	prolog_global_variables_code(PrologGlobalVariables),
	% Do not rename or the 'chr_initialization' predicate
	% without warning SSS
	T = [('$chr_initialization' :- Initializers),(:- initialization '$chr_initialization')|PrologGlobalVariables].

generate_attach_code([],L,L).
generate_attach_code([C|Cs],L,T) :-
	get_store_type(C,StoreType),
	generate_attach_code(StoreType,C,L,L1),
	generate_attach_code(Cs,L1,T).

generate_attach_code(default,C,L,T) :-
	global_list_store_initialisation(C,L,T).
generate_attach_code(multi_inthash(Indexes),C,L,T) :-
	multi_inthash_store_initialisations(Indexes,C,L,L1),
	multi_inthash_via_lookups(Indexes,C,L1,T).
generate_attach_code(multi_hash(Indexes),C,L,T) :-
	multi_hash_store_initialisations(Indexes,C,L,L1),
	multi_hash_lookups(Indexes,C,L1,T).
generate_attach_code(atomic_constants(Index,Constants,_),C,L,T) :-
	constants_initializers(C,Index,Constants),
	atomic_constants_code(C,Index,Constants,L,T).
generate_attach_code(ground_constants(Index,Constants,_),C,L,T) :-
	constants_initializers(C,Index,Constants),
	ground_constants_code(C,Index,Constants,L,T).
generate_attach_code(global_ground,C,L,T) :-
	global_ground_store_initialisation(C,L,T).
generate_attach_code(var_assoc_store(_,_),_,L,L) :-
	use_auxiliary_module(chr_assoc_store).
generate_attach_code(global_singleton,C,L,T) :-
	global_singleton_store_initialisation(C,L,T).
generate_attach_code(multi_store(StoreTypes),C,L,T) :-
	multi_store_generate_attach_code(StoreTypes,C,L,T).
generate_attach_code(identifier_store(Index),C,L,T) :-
	get_identifier_index(C,Index,IIndex),
	( IIndex == 2 ->
		get_identifier_size(ISize),
		functor(Struct,struct,ISize),
		Struct =.. [_,Label|Stores],
		set_elems(Stores,[]),
		Clause1 = new_identifier(Label,Struct),
		functor(Struct2,struct,ISize),
		arg(1,Struct2,Label2),
		Clause2 =
		( user:portray(Struct2) :-
			write('<id:'),
			print(Label2),
			write('>')
		),
		functor(Struct3,struct,ISize),
		arg(1,Struct3,Label3),
		Clause3 = identifier_label(Struct3,Label3),
		L = [Clause1,Clause2,Clause3|T]
	;
		L = T
	).
generate_attach_code(type_indexed_identifier_store(Index,IndexType),C,L,T) :-
	get_type_indexed_identifier_index(IndexType,C,Index,IIndex),
	( IIndex == 2 ->
		identifier_store_initialization(IndexType,L,L1),
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		get_type_indexed_identifier_size(IndexType,ISize),
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		type_indexed_identifier_structure(IndexType,Struct),
		Struct =.. [_,Label|Stores],
		set_elems(Stores,[]),
		type_indexed_identifier_name(IndexType,new_identifier,Name1),
		Clause1 =.. [Name1,Label,Struct],
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		Goal1 =.. [Name1,Label1b,S1b],
		type_indexed_identifier_structure(IndexType,Struct1b),
		Struct1b =.. [_,Label1b|Stores1b],
		set_elems(Stores1b,[]),
		Expansion1 = (S1b = Struct1b),
		Clause1b = user:goal_expansion(Goal1,Expansion1),
		% writeln(Clause1-Clause1b),
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		type_indexed_identifier_structure(IndexType,Struct2),
		arg(1,Struct2,Label2),
		Clause2 =
		( user:portray(Struct2) :-
			write('<id:'),
			print(Label2),
			write('>')
		),
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		type_indexed_identifier_structure(IndexType,Struct3),
		arg(1,Struct3,Label3),
		type_indexed_identifier_name(IndexType,identifier_label,Name3),
		Clause3 =.. [Name3,Struct3,Label3],
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		Goal3b =.. [Name3,S3b,L3b],
		type_indexed_identifier_structure(IndexType,Struct3b),
		arg(1,Struct3b,L3b),
		Expansion3b = (S3b = Struct3b),
		Clause3b = ( user:goal_expansion(Goal3b,Expansion3b) :- writeln(expanding)),
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		identifier_store_name(IndexType,GlobalVariable),
		lookup_identifier_atom(IndexType,X,IX,LookupAtom),
		type_indexed_identifier_name(IndexType,new_identifier,NewIdentifierFunctor),
		NewIdentifierGoal =.. [NewIdentifierFunctor,X,IX],
		Clause4 =
			( LookupAtom :-
				nb_getval(GlobalVariable,HT),
				( lookup_ht(HT,X,[IX]) ->
					true
				;
					NewIdentifierGoal,
					insert_ht(HT,X,IX)
				)
			),
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		lookup_only_identifier_atom(IndexType,Y,IY,LookupOnlyAtom),
		Clause5 =
			( LookupOnlyAtom :-
				nb_getval(GlobalVariable,HT0),
				lookup_ht(HT0,Y,[IY])
			),
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
		L1 = [(:- multifile goal_expansion/2),(:- dynamic goal_expansion/2),Clause1,Clause1b,Clause2,Clause3,Clause3b,Clause4,Clause5|T]
	;
		L = T
	).

constants_initializers(C,Index,Constants) :-
	maplist(constant_initializer(C,Index),Constants).

constant_initializer(C,Index,Constant) :-
	constants_store_name(C,Index,Constant,StoreName),
	prolog_global_variable(StoreName),
	module_initializer(nb_setval(StoreName,[])).

lookup_identifier_atom(Key,X,IX,Atom) :-
	atom_concat('lookup_identifier_',Key,LookupFunctor),
	Atom =.. [LookupFunctor,X,IX].

lookup_only_identifier_atom(Key,X,IX,Atom) :-
	atom_concat('lookup_only_identifier_',Key,LookupFunctor),
	Atom =.. [LookupFunctor,X,IX].

identifier_label_atom(IndexType,IX,X,Atom) :-
	type_indexed_identifier_name(IndexType,identifier_label,Name),
	Atom =.. [Name,IX,X].

multi_store_generate_attach_code([],_,L,L).
multi_store_generate_attach_code([ST|STs],C,L,T) :-
	generate_attach_code(ST,C,L,L1),
	multi_store_generate_attach_code(STs,C,L1,T).

multi_inthash_store_initialisations([],_,L,L).
multi_inthash_store_initialisations([Index|Indexes],FA,L,T) :-
	use_auxiliary_module(chr_integertable_store),
	multi_hash_store_name(FA,Index,StoreName),
	module_initializer((new_iht(HT),nb_setval(StoreName,HT))),
	% L = [(:- (chr_integertable_store:new_ht(HT),nb_setval(StoreName,HT)) )|L1],
	L1 = L,
	multi_inthash_store_initialisations(Indexes,FA,L1,T).
multi_hash_store_initialisations([],_,L,L).
multi_hash_store_initialisations([Index|Indexes],FA,L,T) :-
	use_auxiliary_module(chr_hashtable_store),
	multi_hash_store_name(FA,Index,StoreName),
	prolog_global_variable(StoreName),
	make_init_store_goal(StoreName,HT,InitStoreGoal),
	module_initializer((new_ht(HT),InitStoreGoal)),
	L1 = L,
	multi_hash_store_initialisations(Indexes,FA,L1,T).

global_list_store_initialisation(C,L,T) :-
	( is_stored(C) ->
		global_list_store_name(C,StoreName),
		prolog_global_variable(StoreName),
		make_init_store_goal(StoreName,[],InitStoreGoal),
		module_initializer(InitStoreGoal)
	;
		true
	),
	L = T.
global_ground_store_initialisation(C,L,T) :-
	global_ground_store_name(C,StoreName),
	prolog_global_variable(StoreName),
	make_init_store_goal(StoreName,[],InitStoreGoal),
	module_initializer(InitStoreGoal),
	L = T.
global_singleton_store_initialisation(C,L,T) :-
	global_singleton_store_name(C,StoreName),
	prolog_global_variable(StoreName),
	make_init_store_goal(StoreName,[],InitStoreGoal),
	module_initializer(InitStoreGoal),
	L = T.
identifier_store_initialization(IndexType,L,T) :-
	use_auxiliary_module(chr_hashtable_store),
	identifier_store_name(IndexType,StoreName),
	prolog_global_variable(StoreName),
	make_init_store_goal(StoreName,HT,InitStoreGoal),
	module_initializer((new_ht(HT),InitStoreGoal)),
	L = T.


multi_inthash_via_lookups([],_,L,L).
multi_inthash_via_lookups([Index|Indexes],C,L,T) :-
	multi_hash_lookup_head(C,Index,Key,SuspsList,Head),
	multi_hash_lookup_body(C,inthash,Index,Key,SuspsList,Body),
	L = [(Head :- Body)|L1],
	multi_inthash_via_lookups(Indexes,C,L1,T).
multi_hash_lookups([],_,L,L).
multi_hash_lookups([Index|Indexes],C,L,T) :-
	multi_hash_lookup_head(C,Index,Key,SuspsList,Head),
	multi_hash_lookup_body(C,hash,Index,Key,SuspsList,Body),
	L = [(Head :- Body)|L1],
	multi_hash_lookups(Indexes,C,L1,T).

multi_hash_lookup_head(ConstraintSymbol,Index,Key,SuspsList,Head) :-
	multi_hash_lookup_name(ConstraintSymbol,Index,Name),
	Head =.. [Name,Key,SuspsList].

%%	multi_hash_lookup_body(+ConstraintSymbol,+HashType,+Index,+Key,+SuspsList,-Goal) is det.
%
%	Returns goal that performs hash table lookup.
multi_hash_lookup_body(ConstraintSymbol,HashType,Index,Key,SuspsList,Goal) :-
	% INLINED:
	get_store_type(ConstraintSymbol,multi_store(Stores)),
	( memberchk(atomic_constants(Index,Constants,_),Stores) ->
		( ground(Key) ->
			constants_store_name(ConstraintSymbol,Index,Key,StoreName),
			Goal = nb_getval(StoreName,SuspsList)
		;
			constants_store_index_name(ConstraintSymbol,Index,IndexName),
			Lookup =.. [IndexName,Key,StoreName],
			Goal = (Lookup, nb_getval(StoreName,SuspsList))
		)
	; memberchk(ground_constants(Index,Constants,_),Stores) ->
		( ground(Key) ->
			constants_store_name(ConstraintSymbol,Index,Key,StoreName),
			Goal = nb_getval(StoreName,SuspsList)
		;
			constants_store_index_name(ConstraintSymbol,Index,IndexName),
			Lookup =.. [IndexName,Key,StoreName],
			Goal = (Lookup, nb_getval(StoreName,SuspsList))
		)
	; memberchk(multi_hash([Index]),Stores) ->
		multi_hash_store_name(ConstraintSymbol,Index,StoreName),
		make_get_store_goal(StoreName,HT,GetStoreGoal),
		( HashType == hash, specialized_hash_term_call(ConstraintSymbol,Index,Key,Hash,HashCall) ->
			Goal =
			(
				GetStoreGoal, % nb_getval(StoreName,HT),
				HashCall,     % hash_term(Key,Hash),
				lookup_ht1(HT,Hash,Key,SuspsList)
			)
		;
			lookup_hash_call(HashType,HT,Key,SuspsList,Lookup),
			Goal =
			(
				GetStoreGoal, % nb_getval(StoreName,HT),
				Lookup
			)
		)
	; HashType == inthash ->
			multi_hash_store_name(ConstraintSymbol,Index,StoreName),
			make_get_store_goal(StoreName,HT,GetStoreGoal),
			lookup_hash_call(HashType,HT,Key,SuspsList,Lookup),
			Goal =
			(
				GetStoreGoal, % nb_getval(StoreName,HT),
				Lookup
			)
	% ; % chr_error(internal,'Index ~w for constraint ~w does not exist!\n',[Index,ConstraintSymbol])
		% find alternative index
		%	-> SubIndex + RestIndex
		%	-> SubKey   + RestKeys
		% multi_hash_lookup_goal(ConstraintSymbol,HashType,SubIndex,SubKey,SuspsList,SubGoal),
		% instantiate rest goal?
		% Goal = (SubGoal,RestGoal)
	).


lookup_hash_call(hash,HT,Key,SuspsList,lookup_ht(HT,Key,SuspsList)).
lookup_hash_call(inthash,HT,Key,SuspsList,lookup_iht(HT,Key,SuspsList)).

specialized_hash_term_call(Constraint,Index,Key,Hash,Call) :-
	( ground(Key) ->
		% This is based on a property of SWI-Prolog's
		% hash_term/2 predicate:
		%	the hash value is stable over repeated invocations
		%	of SWI-Prolog
		hash_term(Key,Hash),
		Call = true
%	; Index = [IndexPos],
%	  get_constraint_type(Constraint,ArgTypes),
%	  nth1(IndexPos,ArgTypes,Type),
%	  unalias_type(Type,NormalType),
%	  memberchk_eq(NormalType,[int,natural]) ->
%		( NormalType == int ->
%			Call = (Hash is abs(Key))
%		;
%			Hash = Key,
%			Call = true
%		)
%	;
%		nonvar(Key),
%		specialize_hash_term(Key,NewKey),
%		NewKey \== Key,
%		Call = hash_term(NewKey,Hash)
	).

% specialize_hash_term(Term,NewTerm) :-
%	( ground(Term) ->
%		hash_term(Term,NewTerm)
%	; var(Term) ->
%		NewTerm = Term
%	;
%		Term =.. [F|Args],
%		maplist(specialize_hash_term,Args,NewArgs),
%		NewTerm =.. [F|NewArgs]
%	).

multi_hash_lookup_goal(ConstraintSymbol,HashType,Index,Key,SuspsList,Goal) :-
	% format(' * lookup of ~w on ~w with ~w.\n',[ConstraintSymbol,Index,Key]),
	( /* chr_pp_flag(experiment,off) ->
		true
	; */ atomic(Key) ->
		actual_atomic_multi_hash_keys(ConstraintSymbol,Index,[Key])
	; ground(Key) ->
		actual_ground_multi_hash_keys(ConstraintSymbol,Index,[Key])
	;
		( Index = [Pos],
		  get_constraint_arg_type(ConstraintSymbol,Pos,Type),
		  is_chr_constants_type(Type,_,_)
		->
			true
		;
			actual_non_ground_multi_hash_key(ConstraintSymbol,Index)
		)
	),
	delay_phase_end(validate_store_type_assumptions,
		multi_hash_lookup_body(ConstraintSymbol,HashType,Index,Key,SuspsList,Goal)).

:- chr_constraint actual_atomic_multi_hash_keys/3.
:- chr_option(mode,actual_atomic_multi_hash_keys(+,+,?)).

:- chr_constraint actual_ground_multi_hash_keys/3.
:- chr_option(mode,actual_ground_multi_hash_keys(+,+,?)).

:- chr_constraint actual_non_ground_multi_hash_key/2.
:- chr_option(mode,actual_non_ground_multi_hash_key(+,+)).

/*
actual_atomic_multi_hash_keys(C,Index,Keys)
	==> format('Keys: ~w - ~w : ~w\n', [C,Index,Keys]).

actual_ground_multi_hash_keys(C,Index,Keys)
	==> format('Keys: ~w - ~w : ~w\n', [C,Index,Keys]).

actual_non_ground_multi_hash_key(C,Index)
	==> format('Keys: ~w - ~w : N/A\n', [C,Index]).
*/
actual_atomic_multi_hash_keys(C,Index,Keys1), actual_atomic_multi_hash_keys(C,Index,Keys2)
	<=> append(Keys1,Keys2,Keys0),
	    sort(Keys0,Keys),
	    actual_atomic_multi_hash_keys(C,Index,Keys).

actual_ground_multi_hash_keys(C,Index,Keys1), actual_atomic_multi_hash_keys(C,Index,Keys2)
	<=> append(Keys1,Keys2,Keys0),
	    sort(Keys0,Keys),
	    actual_ground_multi_hash_keys(C,Index,Keys).

actual_ground_multi_hash_keys(C,Index,Keys1), actual_ground_multi_hash_keys(C,Index,Keys2)
	<=> append(Keys1,Keys2,Keys0),
	    sort(Keys0,Keys),
	    actual_ground_multi_hash_keys(C,Index,Keys).

actual_non_ground_multi_hash_key(C,Index) \ actual_non_ground_multi_hash_key(C,Index)
	<=> true.

actual_non_ground_multi_hash_key(C,Index) \ actual_atomic_multi_hash_keys(C,Index,_)
	<=> true.

actual_non_ground_multi_hash_key(C,Index) \ actual_ground_multi_hash_keys(C,Index,_)
	<=> true.

%%	multi_hash_lookup_name(+ConstraintSymbol,+Index,-Name)
%
%	Returns predicate name of hash table lookup predicate.
multi_hash_lookup_name(F/A,Index,Name) :-
	atom_concat_list(Index,IndexName),
	atom_concat_list(['$via1_multi_hash_',F,'___',A,'-',IndexName],Name).

multi_hash_store_name(F/A,Index,Name) :-
	get_target_module(Mod),
	atom_concat_list(Index,IndexName),
	atom_concat_list(['$chr_store_multi_hash_',Mod,'____',F,'___',A,'-',IndexName],Name).

multi_hash_key(FA,Index,Susp,KeyBody,Key) :-
	( Index = [I] ->
		get_dynamic_suspension_term_field(argument(I),FA,Susp,Key,KeyBody)
	;
		maplist(get_dynamic_suspension_term_field1(FA,Susp),Index,Keys,Bodies),
		Key =.. [k|Keys],
		list2conj(Bodies,KeyBody)
	).

get_dynamic_suspension_term_field1(FA,Susp,I,KeyI,Goal) :-
	get_dynamic_suspension_term_field(argument(I),FA,Susp,KeyI,Goal).

multi_hash_key(C,Head,Index,Susp,VarDict,KeyBody,Key) :-
	( Index = [I] ->
		get_suspension_argument_possibly_in_scope(Head,VarDict,Susp,I,Key,KeyBody)
	;
		maplist(get_suspension_argument_possibly_in_scope(Head,VarDict,Susp),Index,Keys,Bodies),
		Key =.. [k|Keys],
		list2conj(Bodies,KeyBody)
	).

get_suspension_argument_possibly_in_scope(Head,VarDict,Susp,Index,Arg,Goal) :-
		arg(Index,Head,OriginalArg),
		( ground(OriginalArg), OriginalArg = '$chr_identifier_match'(Value,KeyType) ->
			functor(Head,F,A),
			lookup_identifier_atom(KeyType,Value,Arg,Goal)
		; term_variables(OriginalArg,OriginalVars),
		  copy_term_nat(OriginalArg-OriginalVars,Arg-Vars),
		  translate(OriginalVars,VarDict,Vars) ->
			Goal = true
		;
			functor(Head,F,A),
			C = F/A,
			get_dynamic_suspension_term_field(argument(Index),C,Susp,Arg,Goal)
		).

multi_hash_key_direct(FA,Index,Susp,Key,UsedVars) :-
	( Index = [I] ->
		UsedVars = [I-Key]
	;
		pairup(Index,Keys,UsedVars),
		Key =.. [k|Keys]
	).

args(Index,Head,KeyArgs) :-
	maplist(arg1(Head),Index,KeyArgs).

split_args(Indexes,Args,IArgs,NIArgs) :-
	split_args(Indexes,Args,1,IArgs,NIArgs).

split_args([],Args,_,[],Args).
split_args([I|Is],[Arg|Args],J,IArgs,NIArgs) :-
	NJ is J + 1,
	( I == J ->
		IArgs = [Arg|Rest],
		split_args(Is,Args,NJ,Rest,NIArgs)
	;
		NIArgs = [Arg|Rest],
		split_args([I|Is],Args,NJ,IArgs,Rest)
	).


%-------------------------------------------------------------------------------
atomic_constants_code(C,Index,Constants,L,T) :-
	constants_store_index_name(C,Index,IndexName),
	maplist(atomic_constant_code(C,Index,IndexName),Constants,Clauses),
	append(Clauses,T,L).

atomic_constant_code(C,Index,IndexName,Constant,Clause) :-
	  constants_store_name(C,Index,Constant,StoreName),
	  Clause =.. [IndexName,Constant,StoreName].

%-------------------------------------------------------------------------------
ground_constants_code(C,Index,Terms,L,T) :-
	constants_store_index_name(C,Index,IndexName),
	maplist(constants_store_name(C,Index),Terms,StoreNames),
	length(Terms,N),
	replicate(N,[],More),
	trie_index([Terms|More],StoreNames,IndexName,L,T).

constants_store_name(F/A,Index,Term,Name) :-
	get_target_module(Mod),
	term_to_atom(Term,Constant),
	term_to_atom(Index,IndexAtom),
	atom_concat_list(['$chr_store_constants_',Mod,'____',F,'___',A,'___',IndexAtom,'___',Constant],Name).

constants_store_index_name(F/A,Index,Name) :-
	get_target_module(Mod),
	term_to_atom(Index,IndexAtom),
	atom_concat_list(['$chr_store_constants_',Mod,'____',F,'___',A,'___',IndexAtom],Name).

% trie index code {{{
trie_index([Patterns|MorePatterns],Results,Prefix,Clauses,Tail) :-
	trie_step(Patterns,Prefix,Prefix,MorePatterns,Results,Clauses,Tail).

trie_step([],_,_,[],[],L,L) :- !.
	% length MorePatterns == length Patterns == length Results
trie_step(Patterns,Symbol,Prefix,MorePatterns,Results,Clauses,T) :-
	MorePatterns = [List|_],
	length(List,N),
	aggregate_all(set(F/A),
		( member(Pattern,Patterns),
		  functor(Pattern,F,A)
		),
		FAs),
	N1 is N + 1,
	trie_step_cases(FAs,N1,Patterns,MorePatterns,Results,Symbol,Prefix,Clauses,T).

trie_step_cases([],_,_,_,_,_,_,Clauses,Clauses).
trie_step_cases([FA|FAs],N,Pattern,MorePatterns,Results,Symbol,Prefix,Clauses,Tail) :-
	trie_step_case(FA,N,Pattern,MorePatterns,Results,Symbol,Prefix,Clauses,Clauses1),
	trie_step_cases(FAs,N,Pattern,MorePatterns,Results,Symbol,Prefix,Clauses1,Tail).

trie_step_case(F/A,N,Patterns,MorePatterns,Results,Symbol,Prefix,[Clause|List],Tail) :-
	Clause = (Head :- Body),
	/* Head = Symbol(IndexPattern,V2,...,Vn,Result) */
	N1 is N  + 1,
	functor(Head,Symbol,N1),
	arg(1,Head,IndexPattern),
	Head =.. [_,_|RestArgs],
	once(append(Vs,[Result],RestArgs)),
	/* IndexPattern = F() */
	functor(IndexPattern,F,A),
	IndexPattern =.. [_|Args],
	append(Args,RestArgs,RecArgs),
	( RecArgs == [Result] ->
		/* nothing more to match on */
		List = Tail,
		Body = true,
		rec_cases(Patterns,_,Results,F/A,_,_,MoreResults),
		MoreResults = [Result]
	;	/* more things to match on */
		rec_cases(Patterns,MorePatterns,Results,F/A,Cases,MoreCases,MoreResults),
		( MoreCases = [OneMoreCase] ->
			/* only one more thing to match on */
			List = Tail,
			Body = true,
			append([Cases,OneMoreCase,MoreResults],RecArgs)
		;
			/* more than one thing to match on */
			/*	[ x1,..., xn]
				[xs1,...,xsn]
			*/
			pairup(Cases,MoreCases,CasePairs),
			common_pattern(CasePairs,CommonPatternPair,DiffVars,Differences),
			append(Args,Vs,[First|Rest]),
			First-Rest = CommonPatternPair,
			% Body = RSymbol(DiffVars,Result)
			fresh_symbol(Prefix,RSymbol),
			append(DiffVars,[Result],RecCallVars),
			Body =.. [RSymbol|RecCallVars],
			maplist(head_tail,Differences,CHs,CTs),
			trie_step(CHs,RSymbol,Prefix,CTs,MoreResults,List,Tail)
		)
	).

:- chr_constraint symbol_count/2.
:- chr_constraint fresh_symbol/2.

symbol_count(Atom,N), fresh_symbol(Atom,Symbol) <=>
	atom_concat(Atom,N,Symbol),
	M is N + 1,
	symbol_count(Atom,M).

fresh_symbol(Atom,Symbol) ==>
	symbol_count(Atom,0).

head_tail([H|T],H,T).

rec_cases([],[],[],_,[],[],[]).
rec_cases([Pattern|Patterns],[MorePattern|MorePatterns],[Result|Results],F/A,Cases,MoreCases,MoreResults) :-
	( functor(Pattern,F,A), Pattern =.. [_|ArgPatterns], append(ArgPatterns,MorePattern,[Case|MoreCase]) ->
		Cases = [Case|NCases],
		MoreCases = [MoreCase|NMoreCases],
		MoreResults = [Result|NMoreResults],
		rec_cases(Patterns,MorePatterns,Results,F/A,NCases,NMoreCases,NMoreResults)
	;
		rec_cases(Patterns,MorePatterns,Results,F/A,Cases,MoreCases,MoreResults)
	).
% }}}

%% common_pattern(+terms,-term,-vars,-differences) is det.
common_pattern(Ts,T,Vars,Differences) :-
	fold1(chr_translate:gct,Ts,T),
	term_variables(T,Vars),
	findall(Vars,member(T,Ts),Differences).

gct(T1,T2,T) :-
	gct_(T1,T2,T,[],_).

gct_(T1,T2,T,Dict0,Dict) :-
	( nonvar(T1),
	  nonvar(T2),
	  functor(T1,F1,A1),
	  functor(T2,F2,A2),
	  F1 == F2,
	  A1 == A2 ->
		functor(T,F1,A1),
		T1 =.. [_|Args1],
		T2 =.. [_|Args2],
		T  =.. [_|Args],
		maplist_dcg(chr_translate:gct_,Args1,Args2,Args,Dict0,Dict)
	;
		/* T is a variable */
		( lookup_eq(Dict0,T1+T2,T) ->
			/* we already have a variable for this difference */
			Dict = Dict0
		;
			/* T is a fresh variable */
			Dict = [(T1+T2)-T|Dict0]
		)
	).


%-------------------------------------------------------------------------------
global_list_store_name(F/A,Name) :-
	get_target_module(Mod),
	atom_concat_list(['$chr_store_global_list_',Mod,'____',F,'___',A],Name).
global_ground_store_name(F/A,Name) :-
	get_target_module(Mod),
	atom_concat_list(['$chr_store_global_ground_',Mod,'____',F,'___',A],Name).
global_singleton_store_name(F/A,Name) :-
	get_target_module(Mod),
	atom_concat_list(['$chr_store_global_singleton_',Mod,'____',F,'___',A],Name).

identifier_store_name(TypeName,Name) :-
	get_target_module(Mod),
	atom_concat_list(['$chr_identifier_lookup_',Mod,'____',TypeName],Name).

:- chr_constraint prolog_global_variable/1.
:- chr_option(mode,prolog_global_variable(+)).

:- chr_constraint prolog_global_variables/1.
:- chr_option(mode,prolog_global_variables(-)).

prolog_global_variable(Name) \ prolog_global_variable(Name) <=> true.

prolog_global_variables(List), prolog_global_variable(Name) <=>
	List = [Name|Tail],
	prolog_global_variables(Tail).
prolog_global_variables(List) <=> List = [].

%% SWI begin
prolog_global_variables_code(Code) :-
	prolog_global_variables(Names),
	( Names == [] ->
		Code = []
	;
		maplist(wrap_in_functor('$chr_prolog_global_variable'),Names,NameDeclarations),
		Code = [(:- dynamic user:exception/3),
			(:- multifile user:exception/3),
			(user:exception(undefined_global_variable,Name,retry) :-
			        (
				'$chr_prolog_global_variable'(Name),
				'$chr_initialization'
			        )
			)
			|
			NameDeclarations
			]
	).
%% SWI end
%% SICStus begin
% prolog_global_variables_code([]).
%% SICStus end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%sbag_member_call(S,L,sysh:mem(S,L)).
sbag_member_call(S,L,'chr sbag_member'(S,L)).
%sbag_member_call(S,L,member(S,L)).
update_mutable_call(A,B,'chr update_mutable'( A, B)).
%update_mutable_call(A,B,setarg(1, B, A)).
create_mutable_call(Value,Mutable,true) :- Mutable = mutable(Value).
% create_mutable_call(Value,Mutable,'chr create_mutable'(Value,Mutable)).

% get_suspension_field(Constraint,Susp,FieldName,Value,(Get0,Get1)) :-
%	get_dynamic_suspension_term_field(FieldName,Constraint,Susp,Field,Get0),
%	create_get_mutable(Value,Field,Get1).
%
% update_suspension_field(Constraint,Susp,FieldName,NewValue,(Get,Set)) :-
%	get_dynamic_suspension_term_field(FieldName,Constraint,Susp,Field,Get),
%         update_mutable_call(NewValue,Field,Set).
%
% get_update_suspension_field(Constraint,Susp,FieldName,Value,NewValue,Get0,Get1,Set) :-
%	get_dynamic_suspension_term_field(FieldName,Constraint,Susp,Field,Get0),
%	create_get_mutable_ref(Value,Field,Get1),
%         update_mutable_call(NewValue,Field,Set).
%
% create_static_suspension_field(Constraint,Susp,FieldName,Value,Create) :-
%	get_static_suspension_term_field(FieldName,Constraint,Susp,Field),
%	create_mutable_call(Value,Field,Create).
%
% get_static_suspension_field(Constraint,Susp,FieldName,Value,Get) :-
%	get_static_suspension_term_field(FieldName,Constraint,Susp,Field),
%	create_get_mutable(Value,Field,Get).
%
% get_update_static_suspension_field(Constraint,Susp,SuspTerm,FieldName,Value,NewValue,Get,Set) :-
%	get_static_suspension_term_field(FieldName,Constraint,SuspTerm,Field),
%	create_get_mutable_ref(Value,Field,Get),
%       update_mutable_call(NewValue,Field,Set).

get_suspension_field(Constraint,Susp,FieldName,Value,Get) :-
	get_dynamic_suspension_term_field(FieldName,Constraint,Susp,Value,Get).

update_suspension_field(Constraint,Susp,FieldName,NewValue,Set) :-
	set_dynamic_suspension_term_field(FieldName,Constraint,Susp,NewValue,Set).

get_update_suspension_field(Constraint,Susp,FieldName,Value,NewValue,true,Get,Set) :-
	get_dynamic_suspension_term_field(FieldName,Constraint,Susp,Value,Get),
	set_dynamic_suspension_term_field(FieldName,Constraint,Susp,NewValue,Set).

create_static_suspension_field(Constraint,Susp,FieldName,Value,true) :-
	get_static_suspension_term_field(FieldName,Constraint,Susp,Value).

get_static_suspension_field(Constraint,Susp,FieldName,Value,true) :-
	get_static_suspension_term_field(FieldName,Constraint,Susp,Value).

get_update_static_suspension_field(Constraint,Susp,SuspTerm,FieldName,Value,NewValue,true,Set) :-
	get_static_suspension_term_field(FieldName,Constraint,SuspTerm,Value),
	set_dynamic_suspension_term_field(FieldName,Constraint,Susp,NewValue,Set).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

enumerate_stores_code(Constraints,[Clause|List]) :-
	Head = '$enumerate_constraints'(Constraint),
	Clause = ( Head :- Body),
	enumerate_store_bodies(Constraints,Constraint,List),
	( List = [] ->
		Body = fail
	;
		Body = ( nonvar(Constraint) ->
				functor(Constraint,Functor,_),
				'$enumerate_constraints'(Functor,Constraint)
		       ;
				'$enumerate_constraints'(_,Constraint)
		       )
	).

enumerate_store_bodies([],_,[]).
enumerate_store_bodies([C|Cs],Constraint,L) :-
	( is_stored(C) ->
		get_store_type(C,StoreType),
		( enumerate_store_body(StoreType,C,Suspension,SuspensionBody) ->
			true
		;
			chr_error(internal,'Could not generate enumeration code for constraint ~w.\n',[C])
		),
		get_dynamic_suspension_term_field(arguments,C,Suspension,Arguments,DynamicGoal),
		C = F/_,
		Constraint0 =.. [F|Arguments],
		Head = '$enumerate_constraints'(F,Constraint),
		Body = (SuspensionBody, DynamicGoal, Constraint = Constraint0),
		L = [(Head :- Body)|T]
	;
		L = T
	),
	enumerate_store_bodies(Cs,Constraint,T).

enumerate_store_body(default,C,Susp,Body) :-
	global_list_store_name(C,StoreName),
	sbag_member_call(Susp,List,Sbag),
	make_get_store_goal(StoreName,List,GetStoreGoal),
	Body =
	(
		GetStoreGoal, % nb_getval(StoreName,List),
		Sbag
	).
%	get_constraint_index(C,Index),
%	get_target_module(Mod),
%	get_max_constraint_index(MaxIndex),
%	Body1 =
%	(
%		'chr default_store'(GlobalStore),
%		get_attr(GlobalStore,Mod,Attr)
%	),
%	( MaxIndex > 1 ->
%		NIndex is Index + 1,
%		sbag_member_call(Susp,List,Sbag),
%		Body2 =
%		(
%			arg(NIndex,Attr,List),
%			Sbag
%		)
%	;
%		sbag_member_call(Susp,Attr,Sbag),
%		Body2 = Sbag
%	),
%	Body = (Body1,Body2).
enumerate_store_body(multi_inthash([Index|_]),C,Susp,Body) :-
	multi_inthash_enumerate_store_body(Index,C,Susp,Body).
enumerate_store_body(multi_hash([Index|_]),C,Susp,Body) :-
	multi_hash_enumerate_store_body(Index,C,Susp,Body).
enumerate_store_body(atomic_constants(Index,Constants,Completeness),C,Susp,Body) :-
	Completeness == complete, % fail if incomplete
	maplist(enumerate_constant_store_body(C,Index,Susps),Constants,Disjuncts),
	list2disj(Disjuncts, Disjunction),
	Body = ( Disjunction, member(Susp,Susps) ).
enumerate_constant_store_body(C,Index,Susps,Constant,nb_getval(StoreName,Susps)) :-
	constants_store_name(C,Index,Constant,StoreName).

enumerate_store_body(ground_constants(Index,Constants,Completeness),C,Susp,Body) :-
	enumerate_store_body(atomic_constants(Index,Constants,Completeness),C,Susp,Body).
enumerate_store_body(global_ground,C,Susp,Body) :-
	global_ground_store_name(C,StoreName),
	sbag_member_call(Susp,List,Sbag),
	make_get_store_goal(StoreName,List,GetStoreGoal),
	Body =
	(
		GetStoreGoal, % nb_getval(StoreName,List),
		Sbag
	).
enumerate_store_body(var_assoc_store(_,_),C,_,Body) :-
	Body = fail.
enumerate_store_body(global_singleton,C,Susp,Body) :-
	global_singleton_store_name(C,StoreName),
	make_get_store_goal(StoreName,Susp,GetStoreGoal),
	Body =
	(
		GetStoreGoal, % nb_getval(StoreName,Susp),
		Susp \== []
	).
enumerate_store_body(multi_store(STs),C,Susp,Body) :-
	( memberchk(global_ground,STs) ->
		enumerate_store_body(global_ground,C,Susp,Body)
	;
		once((
			member(ST,STs),
			enumerate_store_body(ST,C,Susp,Body)
		))
	).
enumerate_store_body(identifier_store(Index),C,Susp,Body) :-
	Body = fail.
enumerate_store_body(type_indexed_identifier_store(Index,IndexType),C,Susp,Body) :-
	Body = fail.

multi_inthash_enumerate_store_body(I,C,Susp,B) :-
	multi_hash_store_name(C,I,StoreName),
	B =
	(
		nb_getval(StoreName,HT),
		value_iht(HT,Susp)
	).
multi_hash_enumerate_store_body(I,C,Susp,B) :-
	multi_hash_store_name(C,I,StoreName),
	make_get_store_goal(StoreName,HT,GetStoreGoal),
	B =
	(
		GetStoreGoal, % nb_getval(StoreName,HT),
		value_ht(HT,Susp)
	).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%    BACKGROUND INFORMATION     (declared using :- chr_declaration)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

:- chr_constraint
        background_info/1,
        background_info/2,
        get_bg_info/1,
        get_bg_info/2,
        get_bg_info_answer/1.

background_info(X), background_info(Y) <=>
	append(X,Y,XY), background_info(XY).
background_info(X) \ get_bg_info(Q) <=> Q=X.
get_bg_info(Q) <=> Q = [].

background_info(T,I), get_bg_info(A,Q) ==>
        copy_term_nat(T,T1),
	subsumes_chk(T1,A)
	|
        copy_term_nat(T-I,A-X),
	get_bg_info_answer([X]).
get_bg_info_answer(X), get_bg_info_answer(Y) <=>
	append(X,Y,XY), get_bg_info_answer(XY).

get_bg_info_answer(X) # Id, get_bg_info(A,Q) <=> Q=X pragma passive(Id).
get_bg_info(_,Q) <=> Q=[].      % no info found on this term

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


:- chr_constraint
	prev_guard_list/8,
	prev_guard_list/6,
	simplify_guards/1,
	set_all_passive/1.

:- chr_option(mode,prev_guard_list(+,+,+,+,+,+,+,+)).
:- chr_option(mode,prev_guard_list(+,+,+,+,+,+)).
:- chr_option(type_declaration,prev_guard_list(any,any,any,any,any,list)).
:- chr_option(mode,simplify_guards(+)).
:- chr_option(mode,set_all_passive(+)).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%    GUARD SIMPLIFICATION
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% If the negation of the guards of earlier rules entails (part of)
% the current guard, the current guard can be simplified. We can only
% use earlier rules with a head that matches if the head of the current
% rule does, and which make it impossible for the current rule to match
% if they fire (i.e. they shouldn't be propagation rules and their
% head constraints must be subsets of those of the current rule).
% At this point, we know for sure that the negation of the guard
% of such a rule has to be true (otherwise the earlier rule would have
% fired, because of the refined operational semantics), so we can use
% that information to simplify the guard by replacing all entailed
% conditions by true/0. As a consequence, the never-stored analysis
% (in a further phase) will detect more cases of never-stored constraints.
%
% e.g.      c(X),d(Y) <=> X > 0 | ...
%           e(X) <=> X < 0 | ...
%           c(X) \ d(Y),e(Z) <=> X =< 0, Z >= 0, ... | ...
%			         \____________/
%                                    true

guard_simplification :-
	( chr_pp_flag(guard_simplification,on) ->
		precompute_head_matchings,
		simplify_guards(1)
	;
		true
	).

%	for every rule, we create a prev_guard_list where the last argument
%	eventually is a list of the negations of earlier guards
rule(RuleNb,Rule) \ simplify_guards(RuleNb)
	<=>
		Rule = pragma(rule(Head1,Head2,Guard,_B),ids(IDs1,IDs2),_Pragmas,_Name,RuleNb),
		append(Head1,Head2,Heads),
		make_head_matchings_explicit_not_negated(Heads,MatchingFreeHeads,Matchings),
		tree_set_empty(Done),
		multiple_occ_constraints_checked(Done),
		apply_guard_wrt_term(Heads,Guard,SubstitutedHeads),

		append(IDs1,IDs2,IDs),
		findall(tuple(C,O,RuleNb)-(-RuleNb),(member(ID,IDs),get_occurrence_from_id(C,O,RuleNb,ID)),HeapData),
		empty_q(EmptyHeap),
		insert_list_q(HeapData,EmptyHeap,Heap),
		next_prev_rule(Heap,_,Heap1),
		next_prev_rule(Heap1,PrevRuleNb,NHeap),
		prev_guard_list(RuleNb,PrevRuleNb,NHeap,MatchingFreeHeads,Guard,[],Matchings,[SubstitutedHeads]),
		NextRule is RuleNb+1,
		simplify_guards(NextRule).

next_prev_rule(Heap,RuleNb,NHeap) :-
	( find_min_q(Heap,_-Priority) ->
		Priority = (-RuleNb),
		normalize_heap(Heap,Priority,NHeap)
	;
		RuleNb = 0,
		NHeap = Heap
	).

normalize_heap(Heap,Priority,NHeap) :-
	( find_min_q(Heap,_-Priority) ->
		delete_min_q(Heap,Heap1,tuple(C,O,_)-_),
		( O > 1 ->
			NO is O -1,
			get_occurrence(C,NO,RuleNb,_),
			insert_q(Heap1,tuple(C,NO,RuleNb)-(-RuleNb),Heap2)
		;
			Heap2 = Heap1
		),
		normalize_heap(Heap2,Priority,NHeap)
	;
		NHeap = Heap
	).

%	no more rule
simplify_guards(_)
	<=>
		true.

%	The negation of the guard of a non-propagation rule is added
%	if its kept head constraints are a subset of the kept constraints of
%	the rule we're working on, and its removed head constraints (at least one)
%	are a subset of the removed constraints.

rule(PrevRuleNb,PrevRule) \ prev_guard_list(RuleNb,PrevRuleNb,Heap,CurrentHeads,G,GuardList,Matchings,GH)
	<=>
		PrevRule = pragma(rule(H1,H2,PrevGuard,_B),_Ids,_Pragmas,_Name,_PrevRuleNb), % PrevRuleNb == _PrevRuleNb
		H1 \== [],
		make_head_matchings_explicit(PrevRuleNb,MatchingFreeHeads,PrevMatchings),
		setof(Renaming,chr_translate:head_subset(MatchingFreeHeads,CurrentHeads,Renaming),Renamings)
    |
		append(H1,H2,Heads),
		compute_derived_info(Renamings,PrevMatchings,MatchingFreeHeads,Heads,PrevGuard,Matchings,CurrentHeads,GH,DerivedInfo,GH_New1),
		append(GuardList,DerivedInfo,GL1),
		normalize_conj_list(GL1,GL),
		append(GH_New1,GH,GH1),
		normalize_conj_list(GH1,GH_New),
		next_prev_rule(Heap,PrevPrevRuleNb,NHeap),
		% PrevPrevRuleNb is PrevRuleNb-1,
		prev_guard_list(RuleNb,PrevPrevRuleNb,NHeap,CurrentHeads,G,GL,Matchings,GH_New).

%	if this isn't the case, we skip this one and try the next rule
prev_guard_list(RuleNb,N,Heap,H,G,GuardList,M,GH)
	<=>
		( N > 0 ->
			next_prev_rule(Heap,N1,NHeap),
			% N1 is N-1,
			prev_guard_list(RuleNb,N1,NHeap,H,G,GuardList,M,GH)
		;
			prev_guard_list(RuleNb,H,G,GuardList,M,GH)
		).

prev_guard_list(RuleNb,H,G,GuardList,M,GH)
	<=>
		GH \== []
	|
		head_types_modes_condition(GH,H,TypeInfo),
		conj2list(TypeInfo,TI),
		term_variables(H,HeadVars),
		append([chr_pp_headvariables(HeadVars)|TI],GuardList,Info),
		normalize_conj_list(Info,InfoL),
                append(H,InfoL,RelevantTerms),
                add_background_info([G|RelevantTerms],BGInfo),
                append(InfoL,BGInfo,AllInfo_),
		normalize_conj_list(AllInfo_,AllInfo),
		prev_guard_list(RuleNb,H,G,AllInfo,M,[]).

head_types_modes_condition([],H,true).
head_types_modes_condition([GH|GHs],H,(TI1, TI2)) :-
	types_modes_condition(H,GH,TI1),
	head_types_modes_condition(GHs,H,TI2).

add_background_info(Term,Info) :-
        get_bg_info(GeneralInfo),
        add_background_info2(Term,TermInfo),
        append(GeneralInfo,TermInfo,Info).

add_background_info2(X,[]) :- var(X), !.
add_background_info2([],[]) :- !.
add_background_info2([X|Xs],Info) :- !,
        add_background_info2(X,Info1),
        add_background_info2(Xs,Infos),
        append(Info1,Infos,Info).

add_background_info2(X,Info) :-
        (functor(X,_,A), A>0 ->
                X =.. [_|XArgs],
                add_background_info2(XArgs,XArgInfo)
        ;
                XArgInfo = []
        ),
        get_bg_info(X,XInfo),
        append(XInfo,XArgInfo,Info).

%%
%	when all earlier guards are added or skipped, we simplify the guard.
%	if it's different from the original one, we change the rule

prev_guard_list(RuleNb,H,G,GuardList,M,[]), rule(RuleNb,Rule)
	<=>
		Rule = pragma(rule(Head1,Head2,G,B),Ids,Pragmas,Name,RuleNb),
		G \== true,		% let's not try to simplify this ;)
		append(M,GuardList,Info),
                (% if guard + context is a contradiction, it should be simplified to "fail"
		  conj2list(G,GL), append(Info,GL,GuardWithContext),
		  guard_entailment:entails_guard(GuardWithContext,fail) ->
                        SimpleGuard = fail
                ;
                % otherwise we try to remove redundant conjuncts
			simplify_guard(G,B,Info,SimpleGuard,NB)
                ),
		G \== SimpleGuard     % only do this if we can change the guard
	|
		rule(RuleNb,pragma(rule(Head1,Head2,SimpleGuard,NB),Ids,Pragmas,Name,RuleNb)),
		prev_guard_list(RuleNb,H,SimpleGuard,GuardList,M,[]).

%%	normalize_conj_list(+List,-NormalList) is det.
%
%	Removes =true= elements and flattens out conjunctions.

normalize_conj_list(List,NormalList) :-
	list2conj(List,Conj),
	conj2list(Conj,NormalList).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%    AUXILIARY PREDICATES	(GUARD SIMPLIFICATION)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

compute_derived_info([],_PrevMatchings,_MatchingFreeHeads,_Heads,_PrevGuard,_Matchings,_H,_GH,[],[]).
compute_derived_info([Renaming1|RestRenamings],PrevMatchings,PrevMatchingFreeHeads,PrevHeads,PrevGuard,Matchings,H,GH,[DerivedInfo1|DerivedInfo2],[GH3|GH_New2]) :-
	copy_term(PrevMatchings-PrevGuard,FreshMatchings),
	variable_replacement(PrevMatchings-PrevGuard,FreshMatchings,ExtraRenaming),
	append(Renaming1,ExtraRenaming,Renaming2),
	list2conj(PrevMatchings,Match),
	negate_b(Match,HeadsDontMatch),
	make_head_matchings_explicit_not_negated2(PrevHeads,PrevMatchingFreeHeads,HeadsMatch),
	list2conj(HeadsMatch,HeadsMatchBut),
	term_variables(Renaming2,RenVars),
	term_variables(PrevMatchings-PrevGuard-HeadsMatch,MGVars),
	new_vars(MGVars,RenVars,ExtraRenaming2),
	append(Renaming2,ExtraRenaming2,Renaming),
	( PrevGuard == true ->		% true can't fail
		Info_ = HeadsDontMatch
	;
		negate_b(PrevGuard,TheGuardFailed),
		Info_ = (HeadsDontMatch ; (HeadsMatchBut, TheGuardFailed))
	),
	copy_with_variable_replacement(Info_,DerivedInfo1,Renaming),
	copy_with_variable_replacement(PrevGuard,RenamedG2,Renaming),
	copy_with_variable_replacement(PrevMatchings,RenamedMatchings_,Renaming),
	list2conj(RenamedMatchings_,RenamedMatchings),
	apply_guard_wrt_term(H,RenamedG2,GH2),
	apply_guard_wrt_term(GH2,RenamedMatchings,GH3),
	compute_derived_info(RestRenamings,PrevMatchings,PrevMatchingFreeHeads,PrevHeads,PrevGuard,Matchings,H,GH,DerivedInfo2,GH_New2).

simplify_guard(G,B,Info,SG,NB) :-
    conj2list(G,LG),
    % writeq(guard_entailment:simplify_guards(Info,B,LG,SGL,NB)),nl,
    guard_entailment:simplify_guards(Info,B,LG,SGL,NB),
    list2conj(SGL,SG).


new_vars([],_,[]).
new_vars([A|As],RV,ER) :-
    ( memberchk_eq(A,RV) ->
	new_vars(As,RV,ER)
    ;
	ER = [A-NewA,NewA-A|ER2],
	new_vars(As,RV,ER2)
    ).

%%	head_subset(+Subset,+MultiSet,-Renaming) is nondet.
%
%	check if a list of constraints is a subset of another list of constraints
%	(multiset-subset), meanwhile computing a variable renaming to convert
%	one into the other.
head_subset(H,Head,Renaming) :-
	head_subset(H,Head,Renaming,[],_).

head_subset([],Remainder,Renaming,Renaming,Remainder).
head_subset([X|Xs],MultiSet,Renaming,Acc,Remainder) :-
	head_member(MultiSet,X,NAcc,Acc,Remainder1),
	head_subset(Xs,Remainder1,Renaming,NAcc,Remainder).

%	check if A is in the list, remove it from Headleft
head_member([X|Xs],A,Renaming,Acc,Remainder) :-
	( variable_replacement(A,X,Acc,Renaming),
		Remainder = Xs
	;
		Remainder = [X|RRemainder],
		head_member(Xs,A,Renaming,Acc,RRemainder)
	).
%-------------------------------------------------------------------------------%
% memoing code to speed up repeated computation

:- chr_constraint precompute_head_matchings/0.

rule(RuleNb,PragmaRule), precompute_head_matchings ==>
	PragmaRule = pragma(rule(H1,H2,_G,_B),_Ids,_Pragmas,_Name,_PrevRuleNb),
	append(H1,H2,Heads),
	make_head_matchings_explicit_(Heads,MatchingFreeHeads,Matchings),
	copy_term_nat(MatchingFreeHeads-Matchings,A-B),
	make_head_matchings_explicit_memo_table(RuleNb,A,B).

precompute_head_matchings <=> true.

:- chr_constraint make_head_matchings_explicit_memo_table/3.
:- chr_constraint make_head_matchings_explicit_memo_lookup/3.

:- chr_option(mode,make_head_matchings_explicit_memo_table(+,?,?)).
:- chr_option(mode,make_head_matchings_explicit_memo_lookup(+,?,?)).

make_head_matchings_explicit_memo_table(RuleNb,NHeads,Matchings) \
		make_head_matchings_explicit_memo_lookup(RuleNb,Q1,Q2)
	<=>
		Q1 = NHeads,
		Q2 = Matchings.
make_head_matchings_explicit_memo_lookup(_,_,_) <=> fail.

make_head_matchings_explicit(RuleNb,MatchingFreeHeads,Matchings) :-
	make_head_matchings_explicit_memo_lookup(RuleNb,A,B),
	copy_term_nat(A-B,MatchingFreeHeads-Matchings).
%-------------------------------------------------------------------------------%

make_head_matchings_explicit_(Heads,MatchingFreeHeads,Matchings) :-
	extract_arguments(Heads,Arguments),
	make_matchings_explicit(Arguments,FreeVariables,[],[],_,Matchings),
	substitute_arguments(Heads,FreeVariables,MatchingFreeHeads).

make_head_matchings_explicit_not_negated(Heads,MatchingFreeHeads,Matchings) :-
	extract_arguments(Heads,Arguments),
	make_matchings_explicit_not_negated(Arguments,FreshVariables,Matchings),
	substitute_arguments(Heads,FreshVariables,MatchingFreeHeads).

make_head_matchings_explicit_not_negated2(Heads,MatchingFreeHeads,Matchings) :-
    extract_arguments(Heads,Arguments1),
    extract_arguments(MatchingFreeHeads,Arguments2),
    make_matchings_explicit_not_negated(Arguments1,Arguments2,Matchings).

%%	extract_arguments(+ListOfConstraints,-ListOfVariables) is det.
%
%	Returns list of arguments of given list of constraints.
extract_arguments([],[]).
extract_arguments([Constraint|Constraints],AllArguments) :-
	Constraint =.. [_|Arguments],
	append(Arguments,RestArguments,AllArguments),
	extract_arguments(Constraints,RestArguments).

%%	substitute_arguments(+InListOfConstraints,ListOfVariables,-OutListOfConstraints) is det.
%
%	Substitutes arguments of constraints with those in the given list.

substitute_arguments([],[],[]).
substitute_arguments([Constraint|Constraints],Variables,[NConstraint|NConstraints]) :-
	functor(Constraint,F,N),
	split_at(N,Variables,Arguments,RestVariables),
	NConstraint =.. [F|Arguments],
	substitute_arguments(Constraints,RestVariables,NConstraints).

make_matchings_explicit([],[],_,MC,MC,[]).
make_matchings_explicit([Arg|Args],[NewVar|NewVars],VarAcc,MatchingCondition,MatchingConditionO,Matchings) :-
	( var(Arg) ->
	    ( memberchk_eq(Arg,VarAcc) ->
	        list2disj(MatchingCondition,MatchingCondition_disj),
	        Matchings = [(MatchingCondition_disj ; NewVar == Arg)|RestMatchings],		% or only =    ??
	        NVarAcc = VarAcc
	    ;
	        Matchings = RestMatchings,
	        NewVar = Arg,
	        NVarAcc = [Arg|VarAcc]
	    ),
	    MatchingCondition2 = MatchingCondition
	;
	    functor(Arg,F,A),
	    Arg =.. [F|RecArgs],
	    make_matchings_explicit(RecArgs,RecVars,VarAcc,MatchingCondition,MatchingCondition_,RecMatchings),
	    FlatArg =.. [F|RecVars],
	    ( RecMatchings == [] ->
	        Matchings = [functor(NewVar,F,A)|RestMatchings]
	    ;
	        list2conj(RecMatchings,ArgM_conj),
	        list2disj(MatchingCondition,MatchingCondition_disj),
	        ArgM_ = (NewVar \= FlatArg ; MatchingCondition_disj ; ArgM_conj),
	        Matchings = [ functor(NewVar,F,A) , ArgM_|RestMatchings]
	    ),
	    MatchingCondition2 = [ NewVar \= FlatArg |MatchingCondition_],
	    term_variables(Args,ArgVars),
	    append(ArgVars,VarAcc,NVarAcc)
	),
	make_matchings_explicit(Args,NewVars,NVarAcc,MatchingCondition2,MatchingConditionO,RestMatchings).


%%	make_matchings_explicit_not_negated(+ListOfTerms,-ListOfVariables,-ListOfMatchings) is det.
%
%	Returns list of new variables and list of pairwise unifications between given list and variables.

make_matchings_explicit_not_negated([],[],[]).
make_matchings_explicit_not_negated([X|Xs],[Var|Vars],Matchings) :-
	Matchings = [Var = X|RMatchings],
	make_matchings_explicit_not_negated(Xs,Vars,RMatchings).

%%	apply_guard_wrt_term(+ListOfConstraints,+Goal,-NewListOfConstraints) is det.
%
%	(Partially) applies substitutions of =Goal= to given list.

apply_guard_wrt_term([],_Guard,[]).
apply_guard_wrt_term([Term|RH],Guard,[NTerm|RGH]) :-
	( var(Term) ->
		apply_guard_wrt_variable(Guard,Term,NTerm)
	;
		Term =.. [F|HArgs],
		apply_guard_wrt_term(HArgs,Guard,NewHArgs),
		NTerm =.. [F|NewHArgs]
	),
	apply_guard_wrt_term(RH,Guard,RGH).

%%	apply_guard_wrt_variable(+Goal,+Variable,-NVariable) is det.
%
%	(Partially) applies goal =Guard= wrt variable.

apply_guard_wrt_variable((Guard1,Guard2),Variable,NVariable) :- !,
	apply_guard_wrt_variable(Guard1,Variable,NVariable1),
	apply_guard_wrt_variable(Guard2,NVariable1,NVariable).
apply_guard_wrt_variable(Guard,Variable,NVariable) :-
	( Guard = (X = Y), Variable == X ->
		NVariable = Y
	; Guard = functor(AVariable,Functor,Arity), Variable == AVariable, ground(Functor), ground(Arity) ->
		functor(NVariable,Functor,Arity)
	;
		NVariable = Variable
	).


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%    ALWAYS FAILING GUARDS
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

prev_guard_list(RuleNb,H,G,GuardList,M,[]),rule(RuleNb,Rule)
	==>
		chr_pp_flag(check_impossible_rules,on),
		Rule = pragma(rule(_,_,G,_),_Ids,_Pragmas,_Name,RuleNb),
		conj2list(G,GL),
		append(M,GuardList,Info),
                append(Info,GL,GuardWithContext),
		guard_entailment:entails_guard(GuardWithContext,fail)
	|
		chr_warning(weird_program,'Heads will never match or guard will always fail in ~@.\n\tThis rule will never fire!\n',[format_rule(Rule)]),
		set_all_passive(RuleNb).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%    HEAD SIMPLIFICATION
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% now we check the head matchings  (guard may have been simplified meanwhile)
prev_guard_list(RuleNb,H,G,GuardList,M,[]) \ rule(RuleNb,Rule)
	<=>
		Rule = pragma(rule(Head1,Head2,G,B),Ids,Pragmas,Name,RuleNb),
		simplify_heads(M,GuardList,G,B,NewM,NewB),
		NewM \== [],
		extract_arguments(Head1,VH1),
		extract_arguments(Head2,VH2),
		extract_arguments(H,VH),
		replace_some_heads(VH1,VH2,VH,NewM,H1,H2,G,B,NewB_),
		substitute_arguments(Head1,H1,NewH1),
		substitute_arguments(Head2,H2,NewH2),
		append(NewB,NewB_,NewBody),
		list2conj(NewBody,BodyMatchings),
		NewRule = pragma(rule(NewH1,NewH2,G,(BodyMatchings,B)),Ids,Pragmas,Name,RuleNb),
		(Head1 \== NewH1 ; Head2 \== NewH2 )
	|
		rule(RuleNb,NewRule).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%    AUXILIARY PREDICATES	(HEAD SIMPLIFICATION)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

replace_some_heads(H1,H2,NH,[],H1,H2,G,Body,[]) :- !.
replace_some_heads([],[H2|RH2],[NH|RNH],[M|RM],[],[H2_|RH2_],G,Body,NewB) :- !,
    ( NH == M ->
	H2_ = M,
	replace_some_heads([],RH2,RNH,RM,[],RH2_,G,Body,NewB)
    ;
	(M = functor(X,F,A), NH == X ->
	    length(A_args,A),
	    (var(H2) ->
		NewB1 = [],
		H2_ =.. [F|A_args]
	    ;
		H2 =.. [F|OrigArgs],
		use_same_args(OrigArgs,A_args,A_args_,G,Body,NewB1),
		H2_ =.. [F|A_args_]
	    ),
	    replace_some_heads([],RH2,RNH,RM,[],RH2_,G,Body,NewB2),
	    append(NewB1,NewB2,NewB)
	;
	    H2_ = H2,
	    replace_some_heads([],RH2,RNH,[M|RM],[],RH2_,G,Body,NewB)
	)
    ).

replace_some_heads([H1|RH1],H2,[NH|RNH],[M|RM],[H1_|RH1_],H2_,G,Body,NewB) :- !,
    ( NH == M ->
	H1_ = M,
	replace_some_heads(RH1,H2,RNH,RM,RH1_,H2_,G,Body,NewB)
    ;
	(M = functor(X,F,A), NH == X ->
	    length(A_args,A),
	    (var(H1) ->
		NewB1 = [],
		H1_ =.. [F|A_args]
	    ;
		H1 =.. [F|OrigArgs],
		use_same_args(OrigArgs,A_args,A_args_,G,Body,NewB1),
		H1_ =.. [F|A_args_]
	    ),
	    replace_some_heads(RH1,H2,RNH,RM,RH1_,H2_,G,Body,NewB2),
	    append(NewB1,NewB2,NewB)
	;
	    H1_ = H1,
	    replace_some_heads(RH1,H2,RNH,[M|RM],RH1_,H2_,G,Body,NewB)
	)
    ).

use_same_args([],[],[],_,_,[]).
use_same_args([OA|ROA],[NA|RNA],[Out|ROut],G,Body,NewB) :-
    var(OA),!,
    Out = OA,
    use_same_args(ROA,RNA,ROut,G,Body,NewB).
use_same_args([OA|ROA],[NA|RNA],[Out|ROut],G,Body,NewB) :-
    nonvar(OA),!,
    ( common_variables(OA,Body) ->
        NewB = [NA = OA|NextB]
    ;
        NewB = NextB
    ),
    Out = NA,
    use_same_args(ROA,RNA,ROut,G,Body,NextB).


simplify_heads([],_GuardList,_G,_Body,[],[]).
simplify_heads([M|RM],GuardList,G,Body,NewM,NewB) :-
    M = (A = B),
    ( (nonvar(B) ; common_variables(B,RM-GuardList)),
	guard_entailment:entails_guard(GuardList,(A=B)) ->
	( common_variables(B,G-RM-GuardList) ->
	    NewB = NextB,
	    NewM = NextM
	;
	    ( common_variables(B,Body) ->
		NewB = [A = B|NextB]
	    ;
		NewB = NextB
	    ),
	    NewM = [A|NextM]
	)
    ;
	( nonvar(B), functor(B,BFu,BAr),
	  guard_entailment:entails_guard([functor(A,BFu,BAr)|GuardList],(A=B)) ->
	    NewB = NextB,
	    ( common_variables(B,G-RM-GuardList) ->
	        NewM = NextM
	    ;
		NewM = [functor(A,BFu,BAr)|NextM]
	    )
	;
	    NewM = NextM,
	    NewB = NextB
	)
    ),
    simplify_heads(RM,[M|GuardList],G,Body,NextM,NextB).

common_variables(B,G) :-
	term_variables(B,BVars),
	term_variables(G,GVars),
	intersect_eq(BVars,GVars,L),
	L \== [].


set_all_passive(RuleNb), occurrence(_,_,RuleNb,ID,_) ==> passive(RuleNb,ID).
set_all_passive(_) <=> true.



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%    OCCURRENCE SUBSUMPTION
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

:- chr_constraint
	first_occ_in_rule/4,
	next_occ_in_rule/6.

:- chr_option(mode,first_occ_in_rule(+,+,+,+)).
:- chr_option(mode,next_occ_in_rule(+,+,+,+,+,+)).

:- chr_constraint multiple_occ_constraints_checked/1.
:- chr_option(mode,multiple_occ_constraints_checked(+)).

prev_guard_list(RuleNb,H,G,GuardList,M,[]),
		occurrence(C,O,RuleNb,ID,_),
		occurrence(C,O2,RuleNb,ID2,_),
		rule(RuleNb,Rule)
		\
		multiple_occ_constraints_checked(Done)
	<=>
		O < O2,
		chr_pp_flag(occurrence_subsumption,on),
		Rule = pragma(rule(H1,H2,_G,_B),_Ids,_Pragmas,_Name,_RuleNb), % RuleNb == _RuleNb
		H1 \== [],
		\+ tree_set_memberchk(C,Done)
	|
		first_occ_in_rule(RuleNb,C,O,ID),
		tree_set_add(Done,C,NDone),
		multiple_occ_constraints_checked(NDone).

%	Find first occurrence of  constraint =C= in rule =RuleNb=
occurrence(C,O,RuleNb,ID,_) \ first_occ_in_rule(RuleNb,C,O2,_)
	<=>
		O < O2
	|
		first_occ_in_rule(RuleNb,C,O,ID).

first_occ_in_rule(RuleNb,C,O,ID_o1)
	<=>
		C = F/A,
		functor(FreshHead,F,A),
		next_occ_in_rule(RuleNb,C,O,ID_o1,[],FreshHead).

%	Skip passive occurrences.
passive(RuleNb,ID_o2), occurrence(C,O2,RuleNb,ID_o2,_) \ next_occ_in_rule(RuleNb,C,O,ID_o1,Cond,FH)
	<=>
		O2 is O+1
	|
		next_occ_in_rule(RuleNb,C,O2,ID_o1,NewCond,FH).

prev_guard_list(RuleNb,H,G,GuardList,M,[]), occurrence(C,O2,RuleNb,ID_o2,_), rule(RuleNb,Rule) \ next_occ_in_rule(RuleNb,C,O,ID_o1,Cond,FH)
	<=>
		O2 is O+1,
		Rule = pragma(rule(H1,H2,G,B),ids(ID1,ID2),_Pragmas,_Name,RuleNb)
    |
		append(H1,H2,Heads),
		add_failing_occ(Rule,Heads,H,ID_o1,ExtraCond,FH,M,C,Repl),
		( ExtraCond == [chr_pp_void_info] ->
			next_occ_in_rule(RuleNb,C,O2,ID_o2,Cond,FH)
		;
			append(ExtraCond,Cond,NewCond),
			add_failing_occ(Rule,Heads,H,ID_o2,CheckCond,FH,M,C,Repl2),
			copy_term(GuardList,FGuardList),
			variable_replacement(GuardList,FGuardList,GLRepl),
			copy_with_variable_replacement(GuardList,GuardList2,Repl),
			copy_with_variable_replacement(GuardList,GuardList3_,Repl2),
			copy_with_variable_replacement(GuardList3_,GuardList3,GLRepl),
			append(NewCond,GuardList2,BigCond),
			append(BigCond,GuardList3,BigCond2),
			copy_with_variable_replacement(M,M2,Repl),
			copy_with_variable_replacement(M,M3,Repl2),
			append(M3,BigCond2,BigCond3),
			append([chr_pp_active_constraint(FH)|M2],BigCond3,Info),
			list2conj(CheckCond,OccSubsum),
			copy_term((NewCond,BigCond2,Info,OccSubsum,FH),(NewCond2,BigCond2_,Info2,OccSubsum2,FH2)),
			( OccSubsum \= chr_pp_void_info ->
				( guard_entailment:entails_guard(Info2,OccSubsum2) ->
					passive(RuleNb,ID_o2)
				;
					true
				)
			;
				true
			),!,
			next_occ_in_rule(RuleNb,C,O2,ID_o2,NewCond,FH)
		).


next_occ_in_rule(RuleNb,C,O,ID,Cond,Args)
	<=>
		true.

prev_guard_list(RuleNb,H,G,GuardList,M,[]), multiple_occ_constraints_checked(Done)
	<=>
		true.

add_failing_occ(Rule,Heads,NH,ID_o1,FailCond,FH,M,C,Repl) :-
	Rule = pragma(rule(H1,H2,G,B),ids(ID1,ID2),_Pragmas,_Name,RuleNb),
	append(ID2,ID1,IDs),
	missing_partner_cond(Heads,NH,IDs,ID_o1,MPCond,H,C),
	copy_term((H,Heads,NH),(FH2,FHeads,NH2)),
	variable_replacement((H,Heads,NH),(FH2,FHeads,NH2),Repl),
	copy_with_variable_replacement(G,FG,Repl),
	extract_explicit_matchings(FG,FG2),
	negate_b(FG2,NotFG),
	copy_with_variable_replacement(MPCond,FMPCond,Repl),
	( subsumes(FH,FH2) ->
	    FailCond = [(NotFG;FMPCond)]
	;
	    % in this case, not much can be done
	    % e.g.    c(f(...)), c(g(...)) <=> ...
	    FailCond = [chr_pp_void_info]
	).

missing_partner_cond([],[],[],ID_o1,fail,H2,C).
missing_partner_cond([H|Hs],[H2|H2s],[ID_o1|IDs],ID_o1,Cond,H,C) :- !,
    missing_partner_cond(Hs,H2s,IDs,ID_o1,Cond,H,C).
missing_partner_cond([H|Hs],[NH|NHs],[ID|IDs],ID_o1,Cond,H2,F/A) :-
    Cond = (chr_pp_not_in_store(H);Cond1),
    missing_partner_cond(Hs,NHs,IDs,ID_o1,Cond1,H2,F/A).

extract_explicit_matchings((A,B),D) :- !,
	( extract_explicit_matchings(A) ->
		extract_explicit_matchings(B,D)
	;
		D = (A,E),
		extract_explicit_matchings(B,E)
	).
extract_explicit_matchings(A,D) :- !,
	( extract_explicit_matchings(A) ->
		D = true
	;
		D = A
	).

extract_explicit_matchings(A=B) :-
    var(A), var(B), !, A=B.
extract_explicit_matchings(A==B) :-
    var(A), var(B), !, A=B.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%    TYPE INFORMATION
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

:- chr_constraint
	type_definition/2,
	type_alias/2,
	constraint_type/2,
	get_type_definition/2,
	get_constraint_type/2.


:- chr_option(mode,type_definition(?,?)).
:- chr_option(mode,get_type_definition(?,?)).
:- chr_option(mode,type_alias(?,?)).
:- chr_option(mode,constraint_type(+,+)).
:- chr_option(mode,get_constraint_type(+,-)).

assert_constraint_type(Constraint,ArgTypes) :-
	( ground(ArgTypes) ->
		constraint_type(Constraint,ArgTypes)
	;
		chr_error(type_error,'Declared argument types "~w" for constraint "~w" must be ground!\n',[ArgTypes,Constraint])
	).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
% Consistency checks of type aliases

type_alias(T1,T2) <=>
	var(T1)
	|
	chr_error(type_error,'Variable alias definition: "~w".\n',[(:- chr_type T1 == T2)]).

type_alias(T1,T2) <=>
	var(T2)
	|
	chr_error(type_error,'Variable alias definition: "~w".\n',[(:- chr_type T1 == T2)]).

type_alias(T,T2) <=>
	functor(T,F,A),
	functor(T2,F,A),
	copy_term((T,T2),(X,Y)), subsumes(X,Y)
	|
	chr_error(type_error,'Cyclic alias definition: "~w".\n',[(T == T2)]).

type_alias(T1,A1), type_alias(T2,A2) <=>
	functor(T1,F,A),
	functor(T2,F,A),
	\+ (T1\=T2)
	|
	copy_term_nat(T1,T1_),
	copy_term_nat(T2,T2_),
	T1_ = T2_,
	chr_error(type_error,
	'Ambiguous type aliases: you have defined \n\t`~w\'\n\t`~w\'\n\tresulting in two definitions for "~w".\n',[T1==A1,T2==A2,T1_]).

type_alias(T,B) \ type_alias(X,T2) <=>
	functor(T,F,A),
	functor(T2,F,A),
	copy_term_nat((X,T2,T,B),(X2,T3,T1,D1)),
	subsumes(T1,T3)
	|
	% chr_info(type_information,'Inferring `~w\' from `~w\' and `~w\'.\n',[X2==D1,X==T2,T==B]),
	type_alias(X2,D1).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
% Consistency checks of type definitions

type_definition(T1,_), type_definition(T2,_)
	<=>
		functor(T1,F,A), functor(T2,F,A)
	|
		chr_error(type_error,'Multiple definitions for type: ~w/~w.\n',[F,A]).

type_definition(T1,_), type_alias(T2,_)
	<=>
		functor(T1,F,A), functor(T2,F,A)
	|
		chr_error(type_error,'Multiple definitions for type, once in a type definition and once as a type alias: ~w/~w.\n',[F,A]).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%%	get_type_definition(+Type,-Definition) is semidet.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

get_type_definition(T,Def)
	<=>
		\+ ground(T)
	|
		chr_error(type_error,'Non-ground type in constraint definition: "~w".\n',[T]).

type_alias(T,D) \ get_type_definition(T2,Def)
	<=>
		nonvar(T),nonvar(T2),functor(T,F,A),functor(T2,F,A),
		copy_term_nat((T,D),(T1,D1)),T1=T2
	|
		( get_type_definition(D1,Def) ->
			true
		;
			chr_error(type_error,'Could not find type definition for "~w" (accessed via alias "~w").\n',[D1,T1]), fail
		).

type_definition(T,D) \ get_type_definition(T2,Def)
	<=>
		nonvar(T),nonvar(T2),functor(T,F,A),functor(T2,F,A),
		copy_term_nat((T,D),(T1,D1)),T1=T2
	|
		Def = D1.

get_type_definition(Type,Def)
	<=>
		atomic_builtin_type(Type,_,_)
	|
		Def = [Type].

get_type_definition(Type,Def)
	<=>
		compound_builtin_type(Type,_,_,_)
	|
		Def = [Type].

get_type_definition(X,Y) <=> fail.

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%%	get_type_definition_det(+Type,-Definition) is det.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
get_type_definition_det(Type,Definition) :-
	( get_type_definition(Type,Definition) ->
		true
	;
		chr_error(type,'Could not find type definition for type `~w\'.\n',[Type])
	).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	get_constraint_type(+ConstraintSymbol,-Types) is semidet.
%
%	Return argument types of =ConstraintSymbol=, but fails if none where
%	declared.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
constraint_type(C,T) \ get_constraint_type(C,Type) <=> Type = T.
get_constraint_type(_,_) <=> fail.

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	get_constraint_type_det(+ConstraintSymbol,-Types) is det.
%
%	Like =get_constraint_type/2=, but returns list of =any= types when
%	no types are declared.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
get_constraint_type_det(ConstraintSymbol,Types) :-
	( get_constraint_type(ConstraintSymbol,Types) ->
		true
	;
		ConstraintSymbol = _ / N,
		replicate(N,any,Types)
	).
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	unalias_type(+Alias,-Type) is det.
%
%	Follows alias chain until base type is reached.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
:- chr_constraint unalias_type/2.

unalias_var @
unalias_type(Alias,BaseType)
	<=>
		var(Alias)
	|
		BaseType = Alias.

unalias_alias @
type_alias(AliasProtoType,ProtoType) \ unalias_type(Alias,BaseType)
	<=>
		nonvar(AliasProtoType),
		nonvar(Alias),
		functor(AliasProtoType,F,A),
		functor(Alias,F,A),
		copy_term_nat((AliasProtoType,ProtoType),(AliasInstance,Type)),
		Alias = AliasInstance
	|
		unalias_type(Type,BaseType).

unalias_type_definition @
type_definition(ProtoType,Definition) \ unalias_type(Alias,BaseType)
	<=>
		nonvar(ProtoType),
		nonvar(Alias),
		functor(ProtoType,F,A),
		functor(Alias,F,A)
	|
		BaseType = Alias.

unalias_atomic_builtin @
unalias_type(Alias,BaseType)
	<=>
		atomic_builtin_type(Alias,_,_)
	|
		BaseType = Alias.

unalias_compound_builtin @
unalias_type(Alias,BaseType)
	<=>
		compound_builtin_type(Alias,_,_,_)
	|
		BaseType = Alias.

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	types_modes_condition(+Heads,+UnrollHeads,-Condition) is det.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
:- chr_constraint types_modes_condition/3.
:- chr_option(mode,types_modes_condition(+,+,?)).
:- chr_option(type_declaration,types_modes_condition(list,list,goal)).

types_modes_condition([],[],T) <=> T=true.

constraint_mode(F/A,Modes) \ types_modes_condition([Head|Heads],[UnrollHead|UnrollHeads],Condition)
	<=>
		functor(Head,F,A)
	|
		Head =.. [_|Args],
		Condition = (ModesCondition, TypesCondition, RestCondition),
		modes_condition(Modes,Args,ModesCondition),
		get_constraint_type_det(F/A,Types),
		UnrollHead =.. [_|RealArgs],
		types_condition(Types,Args,RealArgs,Modes,TypesCondition),
		types_modes_condition(Heads,UnrollHeads,RestCondition).

types_modes_condition([Head|_],_,_)
	<=>
		functor(Head,F,A),
		chr_error(internal,'Mode information missing for ~w.\n',[F/A]).


%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	modes_condition(+Modes,+Args,-Condition) is det.
%
%	Return =Condition= on =Args= that checks =Modes=.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
modes_condition([],[],true).
modes_condition([Mode|Modes],[Arg|Args],Condition) :-
	( Mode == (+) ->
		Condition = ( ground(Arg) , RCondition )
	; Mode == (-) ->
		Condition = ( var(Arg) , RCondition )
	;
		Condition = RCondition
	),
	modes_condition(Modes,Args,RCondition).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	types_condition(+Types,+Args,+UnrollArgs,+Modes,-Condition) is det.
%
%	Return =Condition= on =Args= that checks =Types= given =Modes=.
%	=UnrollArgs= controls the depth of type definition unrolling.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
types_condition([],[],[],[],true).
types_condition([Type|Types],[Arg|Args],[UnrollArg|UnrollArgs],[Mode|Modes],(DisjTypeConditionList,RCondition)) :-
	( Mode == (-) ->
		TypeConditionList = [true]	% TypeConditionList = [var(Arg)] already encoded in modes_condition
	;
		get_type_definition_det(Type,Def),
		type_condition(Def,Arg,UnrollArg,Mode,TypeConditionList1),
		( Mode == (+) ->
			TypeConditionList = TypeConditionList1
		;
			TypeConditionList = [(\+ ground(Arg))|TypeConditionList1]
		)
	),
	list2disj(TypeConditionList,DisjTypeConditionList),
	types_condition(Types,Args,UnrollArgs,Modes,RCondition).

type_condition([],_,_,_,[]).
type_condition([DefCase|DefCases],Arg,UnrollArg,Mode,[Condition|Conditions]) :-
	( var(DefCase) ->
		chr_error(type,'Unexpected variable type in type definition!\n',[]) % Condition = true
	; atomic_builtin_type(DefCase,Arg,Condition) ->
		true
	; compound_builtin_type(DefCase,Arg,Condition,_) ->
		true
	;
		type_def_case_condition(DefCase,Arg,UnrollArg,Mode,Condition)
	),
	type_condition(DefCases,Arg,UnrollArg,Mode,Conditions).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
:- chr_type atomic_builtin_type	--->	any
				;	number
				;	float
				;	int
				;	natural
				;	dense_int
				;	chr_identifier
				;	chr_identifier(any)
				;       /* all possible values are given
					*/
					chr_enum(list(any))
				;	/* all values of interest are given
					   for the other values a handler is provided */
					chr_enum(list(any),any)
				;	/* all possible values appear in rule heads;
					   to distinguish between multiple chr_constants
					   we have a key*/
					chr_constants(any)
				;	/* all relevant values appear in rule heads;
					   for other values a handler is provided */
					chr_constants(any,any).
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%

ast_atomic_builtin_type(Type,AstTerm,Goal) :-
	ast_term_to_term(AstTerm,Term),
	atomic_builtin_type(Type,Term,Goal).

ast_compound_builtin_type(Type,AstTerm,Goal) :-
	ast_term_to_term(AstTerm,Term),
	compound_builtin_type(Type,Term,_,Goal).

atomic_builtin_type(any,_Arg,true).
atomic_builtin_type(dense_int,Arg,(integer(Arg),Arg>=0)).
atomic_builtin_type(int,Arg,integer(Arg)).
atomic_builtin_type(number,Arg,number(Arg)).
atomic_builtin_type(float,Arg,float(Arg)).
atomic_builtin_type(natural,Arg,(integer(Arg),Arg>=0)).
atomic_builtin_type(chr_identifier,_Arg,true).

compound_builtin_type(chr_constants(_),_Arg,true,true).
compound_builtin_type(chr_constants(_,_),_Arg,true,true).
compound_builtin_type(chr_identifier(_),_Arg,true,true).
compound_builtin_type(chr_enum(Constants),Arg,(ground(Arg), memberchk(Arg,Constants)),
		     once(( member(Constant,Constants),
			    unifiable(Arg,Constant,_)
			  )
			 )
	).
compound_builtin_type(chr_enum(_,_),Arg,true,true).

is_chr_constants_type(chr_constants(Key),Key,no).
is_chr_constants_type(chr_constants(Key,ErrorHandler),Key,yes(ErrorHandler)).

is_chr_enum_type(chr_enum(Constants),		Constants,	no).
is_chr_enum_type(chr_enum(Constants,Handler),	Constants,	yes(Handler)).

type_def_case_condition(DefCase,Arg,UnrollArg,Mode,Condition) :-
	( nonvar(DefCase) ->
		functor(DefCase,F,A),
		( A == 0 ->
			Condition = (Arg = DefCase)
		; var(UnrollArg) ->
			Condition = functor(Arg,F,A)
		; functor(UnrollArg,F,A) ->
			Condition = (functor(Arg,F,A),Arg=Template,ArgsCondition),
			DefCase =.. [_|ArgTypes],
			UnrollArg =.. [_|UnrollArgs],
			functor(Template,F,A),
			Template =.. [_|TemplateArgs],
			replicate(A,Mode,ArgModes),
			types_condition(ArgTypes,TemplateArgs,UnrollArgs,ArgModes,ArgsCondition)
		;
			Condition = functor(Arg,F,A)
		)
	;
		chr_error(internal,'Illegal type definition (must be nonvar).\n',[])
	).


%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
% STATIC TYPE CHECKING
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
% Checks head constraints and CHR constraint calls in bodies.
%
% TODO:
%	- type clashes involving built-in types
%	- Prolog built-ins in guard and body
%	- indicate position in terms in error messages
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
:- chr_constraint
	static_type_check/2.

% 1. Check the declared types

constraint_type(Constraint,ArgTypes), static_type_check(_,_)
	==>
		forall(
			( member(ArgType,ArgTypes), sub_term(ArgType,Type) ),
			( get_type_definition(Type,_) ->
				true
			;
				chr_error(type_error,'Undefined type "~w" used in type declaration of "~w".\n',[Type,Constraint])
			)
		).

% 2. Check the rules

:- chr_type type_error_src ---> head(any) ; body(any).

static_type_check(PragmaRules,AstRules)
	<=>
		maplist(static_type_check_rule,PragmaRules,AstRules).

static_type_check_rule(PragmaRule,AstRule) :-
		AstRule = ast_rule(AstHead,_AstGuard,_Guard,AstBody,_Body),
		(
			catch(
				( ast_static_type_check_head(AstHead),
				  ast_static_type_check_body(AstBody)
				),
				type_error(Error),
				( Error = invalid_functor(Src,Term,Type) ->
					chr_error(type_error,'Invalid functor in ~@ of ~@:\n\t\tfound `~w\',\n\t\texpected type `~w\'!\n',
						[chr_translate:format_src(Src),format_rule(PragmaRule),Term,Type])
				; Error = type_clash(Var,Src1,Src2,Type1,Type2) ->
					chr_error(type_error,'Type clash for variable ~w in ~@:\n\t\texpected type ~w in ~@\n\t\texpected type ~w in ~@\n',
						[Var,format_rule(PragmaRule),Type1,chr_translate:format_src(Src1),Type2,chr_translate:format_src(Src2)])
				)
			),
			fail % cleanup constraints
		;
			true
		).

%------------------------------------------------------------------------------%
% Static Type Checking: Head Constraints {{{
ast_static_type_check_head(simplification(AstConstraints)) :-
	maplist(ast_static_type_check_head_constraint,AstConstraints).
ast_static_type_check_head(propagation(AstConstraints)) :-
	maplist(ast_static_type_check_head_constraint,AstConstraints).
ast_static_type_check_head(simpagation(AstConstraints1,AstConstraints2)) :-
	maplist(ast_static_type_check_head_constraint,AstConstraints1),
	maplist(ast_static_type_check_head_constraint,AstConstraints2).

ast_static_type_check_head_constraint(AstConstraint) :-
	AstConstraint = chr_constraint(Symbol,Arguments,_),
	get_constraint_type_det(Symbol,Types),
	maplist(ast_static_type_check_term(head(Head)),Arguments,Types).
% }}}
%------------------------------------------------------------------------------%
% Static Type Checking: Terms {{{
:- chr_constraint ast_static_type_check_term/3.
:- chr_option(mode,ast_static_type_check_term(?,?,?)).
:- chr_option(type_declaration,ast_static_type_check_term(type_error_src,any,any)).

ast_static_type_check_term(_,_,any)
	<=>
		true.

ast_static_type_check_term(Src,var(Id,Var),Type)
	<=>
		ast_static_type_check_var(Id,var(Id,Var),Type,Src).

ast_static_type_check_term(Src,Term,Type)
	<=>
		ast_atomic_builtin_type(Type,Term,Goal)
	|
		( call(Goal) ->
			true
		;
			throw(type_error(invalid_functor(Src,Term,Type)))
		).
ast_static_type_check_term(Src,Term,Type)
	<=>
		ast_compound_builtin_type(Type,Term,Goal)
	|
		( call(Goal) ->
			true
		;
			throw(type_error(invalid_functor(Src,Term,Type)))
		).
type_alias(AType,ADef) \ ast_static_type_check_term(Src,Term,Type)
	<=>
		functor(Type,F,A),
		functor(AType,F,A)
	|
		copy_term_nat(AType-ADef,Type-Def),
		ast_static_type_check_term(Src,Term,Def).

type_definition(AType,ADef) \ ast_static_type_check_term(Src,Term,Type)
	<=>
		functor(Type,F,A),
		functor(AType,F,A)
	|
		copy_term_nat(AType-ADef,Type-Variants),
		ast_functor(Term,TF,TA),
		( member(Variant,Variants), functor(Variant,TF,TA) ->
			ast_args(Term,Args),
			Variant =.. [_|Types],
			maplist(ast_static_type_check_term(Src),Args,Types)
		;
			throw(type_error(invalid_functor(Src,Term,Type)))
		).

ast_static_type_check_term(Src,Term,Type)
	<=>
		chr_error(internal,'Undefined type ~w while type checking term ~w in ~@.\n',[Type,Term,chr_translate:format_src(Src)]).
% }}}
%------------------------------------------------------------------------------%
% Static Type Checking: Variables {{{

:- chr_constraint ast_static_type_check_var/4.
:- chr_option(mode,ast_static_type_check_var(+,?,?,?)).
:- chr_option(type_declaration,ast_static_type_check_var(var_id,any,any,type_error_src)).

type_alias(AType,ADef) \ ast_static_type_check_var(VarId,Var,Type,Src)
	<=>
		functor(AType,F,A),
		functor(Type,F,A)
	|
		copy_term_nat(AType-ADef,Type-Def),
		ast_static_type_check_var(VarId,Var,Def,Src).

ast_static_type_check_var(VarId,Var,Type,Src)
	<=>
		atomic_builtin_type(Type,_,_)
	|
		ast_static_atomic_builtin_type_check_var(VarId,Var,Type,Src).

ast_static_type_check_var(VarId,Var,Type,Src)
	<=>
		compound_builtin_type(Type,_,_,_)
	|
		true.


ast_static_type_check_var(VarId,Var,Type1,Src1), ast_static_type_check_var(VarId,_Var,Type2,Src2)
	<=>
		Type1 \== Type2
	|
		throw(type_error(type_clash(Var,Src1,Src2,Type1,Type2))).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
:- chr_constraint ast_static_atomic_builtin_type_check_var/4.
:- chr_option(mode,ast_static_atomic_builtin_type_check_var(+,?,+,?)).
:- chr_option(type_declaration,ast_static_atomic_builtin_type_check_var(var_id,any,atomic_builtin_type,type_error_src)).

ast_static_atomic_builtin_type_check_var(_,_,any,_) <=> true.
ast_static_atomic_builtin_type_check_var(VarId,_,BuiltinType,_) \ ast_static_atomic_builtin_type_check_var(VarId,_,BuiltinType,_)
	<=>
		true.
ast_static_atomic_builtin_type_check_var(VarId,_,float,_) \ ast_static_atomic_builtin_type_check_var(VarId,_,number,_)
	<=>
		true.
ast_static_atomic_builtin_type_check_var(VarId,_,int,_) \ ast_static_atomic_builtin_type_check_var(VarId,_,number,_)
	<=>
		true.
ast_static_atomic_builtin_type_check_var(VarId,_,natural,_) \ ast_static_atomic_builtin_type_check_var(VarId,_,number,_)
	<=>
		true.
ast_static_atomic_builtin_type_check_var(VarId,_,dense_int,_) \ ast_static_atomic_builtin_type_check_var(VarId,_,number,_)
	<=>
		true.
ast_static_atomic_builtin_type_check_var(VarId,_,natural,_) \ ast_static_atomic_builtin_type_check_var(VarId,_,int,_)
	<=>
		true.
ast_static_atomic_builtin_type_check_var(VarId,_,dense_int,_) \ ast_static_atomic_builtin_type_check_var(VarId,_,int,_)
	<=>
		true.
ast_static_atomic_builtin_type_check_var(VarId,_,dense_int,_) \ ast_static_atomic_builtin_type_check_var(VarId,_,natural,_)
	<=>
		true.
ast_static_atomic_builtin_type_check_var(VarId,Var,Type1,Src1), ast_static_atomic_builtin_type_check_var(VarId,_Var,Type2,Src2)
	<=>
		throw(type_error(type_clash(Var,Src1,Src2,Type1,Type2))).
% }}}
%------------------------------------------------------------------------------%
% Static Type Checking: Bodies {{{
ast_static_type_check_body([]).
ast_static_type_check_body([Goal|Goals]) :-
	ast_symbol(Goal,Symbol),
	get_constraint_type_det(Symbol,Types),
	ast_args(Goal,Args),
	maplist(ast_static_type_check_term(body(Goal)),Args,Types),
	ast_static_type_check_body(Goals).

% }}}
%------------------------------------------------------------------------------%

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	format_src(+type_error_src) is det.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
format_src(head(Head)) :- format('head ~w',[Head]).
format_src(body(Goal)) :- format('body goal ~w',[Goal]).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
% Dynamic type checking
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

:- chr_constraint
	dynamic_type_check/0,
	dynamic_type_check_clauses/1,
	get_dynamic_type_check_clauses/1.

generate_dynamic_type_check_clauses(Clauses) :-
	( chr_pp_flag(debugable,on) ->
		dynamic_type_check,
		get_dynamic_type_check_clauses(Clauses0),
		append(Clauses0,
				[('$dynamic_type_check'(Type,Term) :-
					throw(error(type_error(Type,Term),context(_,'CHR Runtime Type Error')))
				)],
				Clauses)
	;
		Clauses = []
	).

type_definition(T,D), dynamic_type_check
	==>
		copy_term_nat(T-D,Type-Definition),
		maplist(dynamic_type_check_clause(Type),Definition,DynamicChecks),
		dynamic_type_check_clauses(DynamicChecks).
type_alias(A,B), dynamic_type_check
	==>
		copy_term_nat(A-B,Alias-Body),
		dynamic_type_check_alias_clause(Alias,Body,Clause),
		dynamic_type_check_clauses([Clause]).

dynamic_type_check <=>
	findall(
			('$dynamic_type_check'(Type,Term) :- Goal),
			( atomic_builtin_type(Type,Term,Goal) ; compound_builtin_type(Type,Term,Goal,_) ),
			BuiltinChecks
	),
	dynamic_type_check_clauses(BuiltinChecks).

dynamic_type_check_clause(T,DC,Clause) :-
	copy_term(T-DC,Type-DefinitionClause),
	functor(DefinitionClause,F,A),
	functor(Term,F,A),
	DefinitionClause =.. [_|DCArgs],
	Term =.. [_|TermArgs],
	maplist(dynamic_type_check_call,DCArgs,TermArgs,RecursiveCallList),
	list2conj(RecursiveCallList,RecursiveCalls),
	Clause = (
			'$dynamic_type_check'(Type,Term) :-
				RecursiveCalls
	).

dynamic_type_check_alias_clause(Alias,Body,Clause) :-
	Clause = (
			'$dynamic_type_check'(Alias,Term) :-
				'$dynamic_type_check'(Body,Term)
	).

dynamic_type_check_call(Type,Term,Call) :-
	% ( nonvar(Type), atomic_builtin_type(Type,Term,Goal) ->
	%	Call = when(nonvar(Term),Goal)
	% ; nonvar(Type), compound_builtin_type(Type,Term,Goal) ->
	%	Call = when(nonvar(Term),Goal)
	% ;
		( Type == any ->
			Call = true
		;
			Call = when(nonvar(Term),once('$dynamic_type_check'(Type,Term)))
		)
	% )
	.

dynamic_type_check_clauses(C1), dynamic_type_check_clauses(C2)
	<=>
		append(C1,C2,C),
		dynamic_type_check_clauses(C).

get_dynamic_type_check_clauses(Q), dynamic_type_check_clauses(C)
	<=>
		Q = C.
get_dynamic_type_check_clauses(Q)
	<=>
		Q = [].

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
% Atomic Types
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
% Some optimizations can be applied for atomic types...
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

atomic_types_suspended_constraint(C) :-
	C = _/N,
	get_constraint_type(C,ArgTypes),
	get_constraint_mode(C,ArgModes),
	numlist(1,N,Indexes),
	maplist(atomic_types_suspended_constraint(C),ArgTypes,ArgModes,Indexes).

atomic_types_suspended_constraint(C,Type,Mode,Index) :-
	( is_indexed_argument(C,Index) ->
		( Mode == (?) ->
			atomic_type(Type)
		;
			true
		)
	;
		true
	).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	atomic_type(+Type) is semidet.
%
%	Succeeds when all values of =Type= are atomic.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
:- chr_constraint atomic_type/1.

atomic_type(Type) <=> atomic_builtin_type(Type,_,_) | Type \== any.

type_definition(TypePat,Def) \ atomic_type(Type)
	<=>
		functor(Type,F,A), functor(TypePat,F,A)
	|
		maplist(atomic,Def).

type_alias(TypePat,Alias) \ atomic_type(Type)
	<=>
		functor(Type,F,A), functor(TypePat,F,A)
	|
		atomic(Alias),
		copy_term_nat(TypePat-Alias,Type-NType),
		atomic_type(NType).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	enumerated_atomic_type(+Type,-Atoms) is semidet.
%
%	Succeeds when all values of =Type= are atomic
%	and the atom values are finitely enumerable.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
:- chr_constraint enumerated_atomic_type/2.

enumerated_atomic_type(Type,_) <=> atomic_builtin_type(Type,_,_) | fail.

type_definition(TypePat,Def) \ enumerated_atomic_type(Type,Atoms)
	<=>
		functor(Type,F,A), functor(TypePat,F,A)
	|
		maplist(atomic,Def),
		Atoms = Def.

type_alias(TypePat,Alias) \ enumerated_atomic_type(Type,Atoms)
	<=>
		functor(Type,F,A), functor(TypePat,F,A)
	|
		atomic(Alias),
		copy_term_nat(TypePat-Alias,Type-NType),
		enumerated_atomic_type(NType,Atoms).

enumerated_atomic_type(_,_)
	<=>
	fail.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

:- chr_constraint
	stored/3, % constraint,occurrence,(yes/no/maybe)
	stored_completing/3,
	stored_complete/3,
	is_stored/1,
	is_finally_stored/1,
	check_all_passive/2.

:- chr_option(mode,stored(+,+,+)).
:- chr_option(type_declaration,stored(any,int,storedinfo)).
:- chr_type storedinfo ---> yes ; no ; maybe.
:- chr_option(mode,stored_complete(+,+,+)).
:- chr_option(mode,maybe_complementary_guards(+,+,?,?)).
:- chr_option(mode,guard_list(+,+,+,+)).
:- chr_option(mode,check_all_passive(+,+)).
:- chr_option(type_declaration,check_all_passive(any,list)).

% change yes in maybe when yes becomes passive
passive(RuleNb,ID), occurrence(C,O,RuleNb,ID,_) \
	stored(C,O,yes), stored_complete(C,RO,Yesses)
	<=> O < RO | NYesses is Yesses - 1,
	stored(C,O,maybe), stored_complete(C,RO,NYesses).
% change yes in maybe when not observed
ai_not_observed(C,O) \ stored(C,O,yes), stored_complete(C,RO,Yesses)
	<=> O < RO |
	NYesses is Yesses - 1,
	stored(C,O,maybe), stored_complete(C,RO,NYesses).

occurrence(_,_,RuleNb,ID,_), occurrence(C2,_,RuleNb,_,_), stored_complete(C2,RO,0), max_occurrence(C2,MO2)
	==> RO =< MO2 |  % C2 is never stored
	passive(RuleNb,ID).




%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

rule(RuleNb,Rule),passive(RuleNb,Id) ==>
    Rule = pragma(rule(Head1,Head2,G,B),ids([Id|IDs1],IDs2),Pragmas,Name,RuleNb) |
    append(IDs1,IDs2,I), check_all_passive(RuleNb,I).

rule(RuleNb,Rule),passive(RuleNb,Id) ==>
    Rule = pragma(rule(Head1,Head2,G,B),ids([],[Id|IDs2]),Pragmas,Name,RuleNb) |
    check_all_passive(RuleNb,IDs2).

passive(RuleNb,Id) \ check_all_passive(RuleNb,[Id|IDs]) <=>
    check_all_passive(RuleNb,IDs).

rule(RuleNb,Rule) \ check_all_passive(RuleNb,[]) <=>
    chr_warning(weird_program,'All heads passive in ~@.\n\tThis rule never fires. Please check your program.\n',[format_rule(Rule)]).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% collect the storage information
stored(C,O,yes) \ stored_completing(C,O,Yesses)
	<=> NO is O + 1, NYesses is Yesses + 1,
	    stored_completing(C,NO,NYesses).
stored(C,O,maybe) \ stored_completing(C,O,Yesses)
	<=> NO is O + 1,
	    stored_completing(C,NO,Yesses).

stored(C,O,no) \ stored_completing(C,O,Yesses)
	<=> stored_complete(C,O,Yesses).
stored_completing(C,O,Yesses)
	<=> stored_complete(C,O,Yesses).

stored_complete(C,O,Yesses), occurrence(C,O2,RuleNb,Id,_) ==>
	O2 > O | passive(RuleNb,Id).

% decide whether a constraint is stored
max_occurrence(C,MO), stored_complete(C,RO,0) \ is_stored(C)
	<=> RO =< MO | fail.
is_stored(C) <=>  true.

% decide whether a constraint is suspends after occurrences
max_occurrence(C,MO), stored_complete(C,RO,_) \ is_finally_stored(C)
	<=> RO =< MO | fail.
is_finally_stored(C) <=>  true.

storage_analysis(Constraints) :-
	( chr_pp_flag(storage_analysis,on) ->
		check_constraint_storages(Constraints)
	;
		true
	).

check_constraint_storages(Symbols) :- maplist(check_constraint_storage,Symbols).

check_constraint_storage(C) :-
	get_max_occurrence(C,MO),
	check_occurrences_storage(C,1,MO).

check_occurrences_storage(C,O,MO) :-
	( O > MO ->
		stored_completing(C,1,0)
	;
		check_occurrence_storage(C,O),
		NO is O + 1,
		check_occurrences_storage(C,NO,MO)
	).

check_occurrence_storage(C,O) :-
	get_occurrence(C,O,RuleNb,ID,OccType),
	( is_passive(RuleNb,ID) ->
		stored(C,O,maybe)
	;
		get_rule(RuleNb,PragmaRule),
		PragmaRule = pragma(rule(Heads1,Heads2,Guard,Body),ids(IDs1,IDs2),_,_,_),
		( OccType == simplification, select2(ID,Head1,IDs1,Heads1,RIDs1,RHeads1) ->
			check_storage_head1(Head1,O,Heads1,Heads2,Guard)
		; OccType == propagation, select2(ID,Head2,IDs2,Heads2,RIDs2,RHeads2) ->
			check_storage_head2(Head2,O,Heads1,Body)
		)
	).

check_storage_head1(Head,O,H1,H2,G) :-
	functor(Head,F,A),
	C = F/A,
	( H1 == [Head],
	  H2 == [],
          % writeq(guard_entailment:entails_guard([chr_pp_headvariables(Head)],G)),nl,
	  guard_entailment:entails_guard([chr_pp_headvariables(Head)],G),
	  Head =.. [_|L],
	  no_matching(L,[]) ->
		stored(C,O,no)
	;
		stored(C,O,maybe)
	).

no_matching([],_).
no_matching([X|Xs],Prev) :-
	var(X),
	\+ memberchk_eq(X,Prev),
	no_matching(Xs,[X|Prev]).

check_storage_head2(Head,O,H1,B) :-
	functor(Head,F,A),
	C = F/A,
	( %(
		( H1 \== [], B == true )
	  %;
	  % \+ is_observed(F/A,O)  % always fails because observation analysis has not been performed yet
	  %)
	->
		stored(C,O,maybe)
	;
		stored(C,O,yes)
	).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%  ____        _         ____                      _ _       _   _
%% |  _ \ _   _| | ___   / ___|___  _ __ ___  _ __ (_) | __ _| |_(_) ___  _ __
%% | |_) | | | | |/ _ \ | |   / _ \| '_ ` _ \| '_ \| | |/ _` | __| |/ _ \| '_ \
%% |  _ <| |_| | |  __/ | |__| (_) | | | | | | |_) | | | (_| | |_| | (_) | | | |
%% |_| \_\\__,_|_|\___|  \____\___/|_| |_| |_| .__/|_|_|\__,_|\__|_|\___/|_| |_|
%%                                           |_|

constraints_code(Constraints,Clauses) :-
	(chr_pp_flag(reduced_indexing,on),
		forall(C,Constraints,chr_translate:only_ground_indexed_arguments(C)) ->
	    none_suspended_on_variables
	;
	    true
        ),
	constraints_code1(Constraints,Clauses,[]).

%===============================================================================
:- chr_constraint constraints_code1/3.
:- chr_option(mode,constraints_code1(+,+,+)).
:- chr_option(type_declaration,constraints_code1(list,any,any)).
%-------------------------------------------------------------------------------
constraints_code1([],L,T) <=> L = T.
constraints_code1([C|RCs],L,T)
	<=>
		constraint_code(C,L,T1),
		constraints_code1(RCs,T1,T).
%===============================================================================
:- chr_constraint constraint_code/3.
:- chr_option(mode,constraint_code(+,+,+)).
%-------------------------------------------------------------------------------
%%	Generate code for a single CHR constraint
constraint_code(Constraint, L, T)
	<=>	true
	|	( (chr_pp_flag(debugable,on) ;
		  is_stored(Constraint), ( has_active_occurrence(Constraint); chr_pp_flag(late_allocation,off)),
                  ( may_trigger(Constraint) ;
		    get_allocation_occurrence(Constraint,AO),
		    get_max_occurrence(Constraint,MO), MO >= AO ) )
		   ->
			constraint_prelude(Constraint,Clause),
			add_dummy_location(Clause,LocatedClause),
			L = [LocatedClause | L1]
		;
			L = L1
		),
		Id = [0],
		occurrences_code(Constraint,1,Id,NId,L1,L2),
		gen_cond_attach_clause(Constraint,NId,L2,T).

%===============================================================================
%%	Generate prelude predicate for a constraint.
%%	f(...) :- f/a_0(...,Susp).
constraint_prelude(F/A, Clause) :-
	vars_susp(A,Vars,Susp,VarsSusp),
	Head =.. [ F | Vars],
	make_suspension_continuation_goal(F/A,VarsSusp,Continuation),
	build_head(F,A,[0],VarsSusp,Delegate),
	( chr_pp_flag(debugable,on) ->
		insert_constraint_goal(F/A,Susp,Vars,InsertCall),
		attach_constraint_atom(F/A,Vars2,Susp,AttachCall),
		delay_phase_end(validate_store_type_assumptions,chr_translate:update_suspension_field(F/A,Susp,state,inactive,Inactive)),
		insert_constraint_internal_constraint_goal(F/A, Vars2, Susp, Continuation, Vars,InsertGoal),

		( get_constraint_type(F/A,ArgTypeList) ->
			maplist(dynamic_type_check_call,ArgTypeList,Vars,DynamicTypeCheckList),
			list2conj(DynamicTypeCheckList,DynamicTypeChecks)
		;
			DynamicTypeChecks = true
		),

		Clause =
			( Head :-
				DynamicTypeChecks,
				InsertGoal,
				InsertCall,
				AttachCall,
				Inactive,
				'chr debug_event'(insert(Head#Susp)),
			        (
					'chr debug_event'(call(Susp)),
			                Delegate
				;
					'chr debug_event'(fail(Susp)), !,
					fail
				),
			        (
					'chr debug_event'(exit(Susp))
			        ;
					'chr debug_event'(redo(Susp)),
				        fail
			        )
			)
	; get_allocation_occurrence(F/A,0) ->
		gen_insert_constraint_internal_goal(F/A,Goal,VarsSusp,Vars,Susp),
		delay_phase_end(validate_store_type_assumptions,chr_translate:update_suspension_field(F/A,Susp,state,inactive,Inactive)),
		Clause = ( Head  :- Goal, Inactive, Delegate )
	;
		Clause = ( Head  :- Delegate )
	).

make_suspension_continuation_goal(F/A,VarsSusp,Goal) :-
	( may_trigger(F/A) ->
		build_head(F,A,[0],VarsSusp,Delegate),
		( chr_pp_flag(debugable,off) ->
			Goal = Delegate
		;
			get_target_module(Mod),
			Goal = Mod:Delegate
		)
	;
		Goal = true
	).

%===============================================================================
:- chr_constraint has_active_occurrence/1, has_active_occurrence/2.
:- chr_option(mode,has_active_occurrence(+)).
:- chr_option(mode,has_active_occurrence(+,+)).

:- chr_constraint memo_has_active_occurrence/1.
:- chr_option(mode,memo_has_active_occurrence(+)).
%-------------------------------------------------------------------------------
memo_has_active_occurrence(C) \ has_active_occurrence(C) <=> true.
has_active_occurrence(C) <=> has_active_occurrence(C,1), memo_has_active_occurrence(C).

max_occurrence(C,MO) \ has_active_occurrence(C,O) <=>
	O > MO | fail.
passive(RuleNb,ID),occurrence(C,O,RuleNb,ID,_) \
	has_active_occurrence(C,O) <=>
	NO is O + 1,
	has_active_occurrence(C,NO).
has_active_occurrence(C,O) <=> true.
%===============================================================================

gen_cond_attach_clause(F/A,Id,L,T) :-
	( is_finally_stored(F/A) ->
		get_allocation_occurrence(F/A,AllocationOccurrence),
		get_max_occurrence(F/A,MaxOccurrence),
		( chr_pp_flag(debugable,off), MaxOccurrence < AllocationOccurrence ->
			( only_ground_indexed_arguments(F/A) ->
				gen_insert_constraint_internal_goal(F/A,Body,AllArgs,Args,Susp)
			;
				gen_cond_attach_goal(F/A,Body,AllArgs,Args,Susp)
			)
		;	vars_susp(A,Args,Susp,AllArgs),
			gen_uncond_attach_goal(F/A,Susp,Args,Body,_)
		),
		build_head(F,A,Id,AllArgs,Head),
		Clause = ( Head :- Body ),
		add_dummy_location(Clause,LocatedClause),
		L = [LocatedClause | T]
	;
		L = T
	).

:- chr_constraint use_auxiliary_predicate/1.
:- chr_option(mode,use_auxiliary_predicate(+)).

:- chr_constraint use_auxiliary_predicate/2.
:- chr_option(mode,use_auxiliary_predicate(+,+)).

:- chr_constraint is_used_auxiliary_predicate/1.
:- chr_option(mode,is_used_auxiliary_predicate(+)).

:- chr_constraint is_used_auxiliary_predicate/2.
:- chr_option(mode,is_used_auxiliary_predicate(+,+)).


use_auxiliary_predicate(P) \ use_auxiliary_predicate(P) <=> true.

use_auxiliary_predicate(P,C) \ use_auxiliary_predicate(P,C) <=> true.

use_auxiliary_predicate(P) \ is_used_auxiliary_predicate(P) <=> true.

use_auxiliary_predicate(P,_) \ is_used_auxiliary_predicate(P) <=> true.

is_used_auxiliary_predicate(P) <=> fail.

use_auxiliary_predicate(P) \ is_used_auxiliary_predicate(P,_) <=> true.
use_auxiliary_predicate(P,C) \ is_used_auxiliary_predicate(P,C) <=> true.

is_used_auxiliary_predicate(P,C) <=> fail.

%------------------------------------------------------------------------------%
% Only generate import statements for actually used modules.
%------------------------------------------------------------------------------%

:- chr_constraint use_auxiliary_module/1.
:- chr_option(mode,use_auxiliary_module(+)).

:- chr_constraint is_used_auxiliary_module/1.
:- chr_option(mode,is_used_auxiliary_module(+)).


use_auxiliary_module(P) \ use_auxiliary_module(P) <=> true.

use_auxiliary_module(P) \ is_used_auxiliary_module(P) <=> true.

is_used_auxiliary_module(P) <=> fail.

	% only called for constraints with
	% at least one
	% non-ground indexed argument
gen_cond_attach_goal(F/A,Goal,AllArgs,Args,Susp) :-
	vars_susp(A,Args,Susp,AllArgs),
	make_suspension_continuation_goal(F/A,AllArgs,Closure),
	( get_store_type(F/A,var_assoc_store(_,_)) ->
		Attach = true
	;
		attach_constraint_atom(F/A,Vars,Susp,Attach)
	),
	FTerm =.. [F|Args],
	insert_constraint_goal(F/A,Susp,Args,InsertCall),
	insert_constraint_internal_constraint_goal(F/A, Vars, Susp, Closure, Args,InsertGoal),
	( may_trigger(F/A) ->
		activate_constraint_goal(F/A,(InsertCall,Attach),Vars,Susp,_,ActivateGoal),
		Goal =
		(
			( var(Susp) ->
				InsertGoal, % insert_constraint_internal(Stored,Vars,Susp,Closure,F,Args)
				InsertCall,
				Attach
			;
				ActivateGoal % activate_constraint(Stored,Vars,Susp,_)
			)
		)
	;
		Goal =
		(
			InsertGoal, % insert_constraint_internal(Stored,Vars,Susp,Closure,F,Args),
			InsertCall,
			Attach
		)
	).

gen_insert_constraint_internal_goal(F/A,Goal,AllArgs,Args,Susp) :-
	vars_susp(A,Args,Susp,AllArgs),
	make_suspension_continuation_goal(F/A,AllArgs,Cont),
	( \+ only_ground_indexed_arguments(F/A), \+ get_store_type(F/A,var_assoc_store(_,_)) ->
		attach_constraint_atom(F/A,Vars,Susp,Attach)
	;
		Attach = true
	),
	FTerm =.. [F|Args],
	insert_constraint_goal(F/A,Susp,Args,InsertCall),
	insert_constraint_internal_constraint_goal(F/A, Vars, Susp, Cont, Args,InsertInternalGoal),
	( only_ground_indexed_arguments(F/A), chr_pp_flag(debugable,off) ->
	    Goal =
	    (
		InsertInternalGoal, % insert_constraint_internal(Susp,F,Args),
		InsertCall
	    )
	;
	    Goal =
	    (
		InsertInternalGoal, % insert_constraint_internal(_,Vars,Susp,Cont,F,Args),
		InsertCall,
		Attach
	    )
	).

gen_uncond_attach_goal(FA,Susp,Args,AttachGoal,Generation) :-
	( \+ only_ground_indexed_arguments(FA), \+ get_store_type(FA,var_assoc_store(_,_)) ->
		attach_constraint_atom(FA,Vars,Susp,Attach)
	;
		Attach = true
	),
	insert_constraint_goal(FA,Susp,Args,InsertCall),
	( chr_pp_flag(late_allocation,on) ->
		activate_constraint_goal(FA,(InsertCall,Attach),Vars,Susp,Generation,AttachGoal)
	;
		activate_constraint_goal(FA,true,Vars,Susp,Generation,AttachGoal)
	).

%-------------------------------------------------------------------------------
:- chr_constraint occurrences_code/6.
:- chr_option(mode,occurrences_code(+,+,+,+,+,+)).
%-------------------------------------------------------------------------------
max_occurrence(C,MO) \ occurrences_code(C,O,Id,NId,L,T)
	 <=>	O > MO
	|	NId = Id, L = T.
occurrences_code(C,O,Id,NId,L,T)
	<=>
		occurrence_code(C,O,Id,Id1,L,L1),
		NO is O + 1,
		occurrences_code(C,NO,Id1,NId,L1,T).
%-------------------------------------------------------------------------------
:- chr_constraint occurrence_code/6.
:- chr_option(mode,occurrence_code(+,+,+,+,+,+)).
%-------------------------------------------------------------------------------
occurrence(C,O,RuleNb,ID,_), passive(RuleNb,ID) \ occurrence_code(C,O,Id,NId,L,T)
	<=>
		( named_history(RuleNb,_,_) ->
			does_use_history(C,O)
		;
			true
		),
		NId = Id,
		L = T.
occurrence(C,O,RuleNb,ID,_), rule(RuleNb,PragmaRule) \ occurrence_code(C,O,Id,NId,L,T)
	<=>	true |
		PragmaRule = pragma(rule(Heads1,Heads2,_,_),ids(IDs1,IDs2),_,_,_),
		( select2(ID,Head1,IDs1,Heads1,RIDs1,RHeads1) ->
			NId = Id,
			head1_code(Head1,ID,RHeads1,RIDs1,PragmaRule,C,O,Id,L,T)
		; select2(ID,Head2,IDs2,Heads2,RIDs2,RHeads2) ->

			head2_code(Head2,ID,RHeads2,RIDs2,PragmaRule,C,O,Id,L,L1),
			( should_skip_to_next_id(C,O) ->
				inc_id(Id,NId),
				( unconditional_occurrence(C,O) ->
					L1 = T
				;
					gen_alloc_inc_clause(C,O,Id,L1,T)
				)
			;
				NId = Id,
				L1 = T
			)
		).

occurrence_code(C,O,_,_,_,_)
	<=>
		chr_error(internal,'occurrence_code/6: missing information to compile ~w:~w\n',[C,O]).
%-------------------------------------------------------------------------------

%%	Generate code based on one removed head of a CHR rule
head1_code(Head,ID,OtherHeads,OtherIDs,PragmaRule,FA,O,Id,L,T) :-
	PragmaRule = pragma(Rule,_,_,_Name,RuleNb),
	Rule = rule(_,Head2,_,_),
	( Head2 == [] ->
		reorder_heads(RuleNb,Head,OtherHeads,OtherIDs,NOtherHeads,NOtherIDs),
		simplification_code(Head,ID,NOtherHeads,NOtherIDs,PragmaRule,FA,O,Id,L,T)
	;
		simpagation_head1_code(Head,ID,OtherHeads,OtherIDs,PragmaRule,FA,O,Id,L,T)
	).

%% Generate code based on one persistent head of a CHR rule
head2_code(Head,ID,OtherHeads,OtherIDs,PragmaRule,FA,O,Id,L,T) :-
	PragmaRule = pragma(Rule,_,_,_Name,RuleNb),
	Rule = rule(Head1,_,_,_),
	( Head1 == [] ->
		reorder_heads(RuleNb,Head,OtherHeads,OtherIDs,NOtherHeads,NOtherIDs),
		propagation_code(Head,ID,NOtherHeads,NOtherIDs,Rule,RuleNb,FA,O,Id,L,T)
	;
		simpagation_head2_code(Head,ID,OtherHeads,OtherIDs,PragmaRule,FA,O,Id,L,T)
	).

gen_alloc_inc_clause(F/A,O,Id,L,T) :-
	vars_susp(A,Vars,Susp,VarsSusp),
	build_head(F,A,Id,VarsSusp,Head),
	inc_id(Id,IncId),
	build_head(F,A,IncId,VarsSusp,CallHead),
	gen_occ_allocation(F/A,O,Vars,Susp,ConditionalAlloc),
	Clause =
	(
		Head :-
			ConditionalAlloc,
			CallHead
	),
	add_dummy_location(Clause,LocatedClause),
	L = [LocatedClause|T].

gen_occ_allocation(FA,O,Vars,Susp,Goal) :-
	get_allocation_occurrence(FA,AO),
	get_occurrence_code_id(FA,AO,AId),
	get_occurrence_code_id(FA,O,Id),
	( chr_pp_flag(debugable,off), Id == AId ->
		allocate_constraint_goal(FA,Susp,Vars,Goal0),
		( may_trigger(FA) ->
			Goal = (var(Susp) -> Goal0 ; true)
		;
			Goal = Goal0
		)
	;
		Goal = true
	).

gen_occ_allocation_in_guard(FA,O,Vars,Susp,Goal) :-
	get_allocation_occurrence(FA,AO),
	( chr_pp_flag(debugable,off), O < AO ->
		allocate_constraint_goal(FA,Susp,Vars,Goal0),
		( may_trigger(FA) ->
			Goal = (var(Susp) -> Goal0 ; true)
		;
			Goal = Goal0
		)
	;
		Goal = true
	).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% Reorders guard goals with respect to partner constraint retrieval goals and
% active constraint. Returns combined partner retrieval + guard goal.

guard_via_reschedule_new(Retrievals,GuardList,Prelude,GuardListSkeleton,LookupSkeleton,GoalSkeleton) :-
	( chr_pp_flag(guard_via_reschedule,on) ->
		guard_via_reschedule_main_new(Retrievals,GuardList,Prelude,GuardListSkeleton,LookupSkeleton,ScheduleSkeleton),
		list2conj(ScheduleSkeleton,GoalSkeleton)
	;
		length(Retrievals,RL), length(LookupSkeleton,RL),
		length(GuardList,GL), length(GuardListSkeleton,GL),
		append(LookupSkeleton,GuardListSkeleton,GoalListSkeleton),
		list2conj(GoalListSkeleton,GoalSkeleton)
	).
guard_via_reschedule_main_new(PartnerLookups,GuardList,ActiveHead,
	GuardListSkeleton,LookupSkeleton,ScheduleSkeleton) :-
	initialize_unit_dictionary(ActiveHead,Dict),
	maplist(wrap_in_functor(lookup),PartnerLookups,WrappedPartnerLookups),
	maplist(wrap_in_functor(guard),GuardList,WrappedGuardList),
	build_units(WrappedPartnerLookups,WrappedGuardList,Dict,Units),
	dependency_reorder(Units,NUnits),
	wrappedunits2lists(NUnits,IndexedGuardListSkeleton,LookupSkeleton,ScheduleSkeleton),
	sort(IndexedGuardListSkeleton,SortedIndexedGuardListSkeleton),
	snd_of_pairs(SortedIndexedGuardListSkeleton,GuardListSkeleton).

wrappedunits2lists([],[],[],[]).
wrappedunits2lists([unit(N,WrappedGoal,_,_)|Units],Gs,Ls,Ss) :-
	Ss = [GoalCopy|TSs],
	( WrappedGoal = lookup(Goal) ->
		Ls = [GoalCopy|TLs],
		Gs = TGs
	; WrappedGoal = guard(Goal) ->
		Gs = [N-GoalCopy|TGs],
		Ls = TLs
	),
	wrappedunits2lists(Units,TGs,TLs,TSs).

guard_splitting(Rule,SplitGuardList) :-
	Rule = rule(H1,H2,Guard,_),
	append(H1,H2,Heads),
	conj2list(Guard,GuardList),
	term_variables(Heads,HeadVars),
	split_off_simple_guard_new(GuardList,HeadVars,GuardPrefix,RestGuardList),
	append(GuardPrefix,[RestGuard],SplitGuardList),
	term_variables(RestGuardList,GuardVars1),
	% variables that are declared to be ground don't need to be locked
	ground_vars(Heads,GroundVars),
	list_difference_eq(HeadVars,GroundVars,LockableHeadVars),
	intersect_eq(LockableHeadVars,GuardVars1,GuardVars),
	maplist(chr_lock,GuardVars,Locks),
	maplist(chr_unlock,GuardVars,Unlocks),
	list2conj(Locks,LockPhase),
	list2conj(Unlocks,UnlockPhase),
	list2conj(RestGuardList,RestGuard1),
	RestGuard = (LockPhase,(RestGuard1,UnlockPhase)).

guard_body_copies3(Rule,GuardList,VarDict,GuardCopyList,BodyCopy) :-
	Rule = rule(_,_,_,Body),
	my_term_copy(GuardList,VarDict,VarDict2,GuardCopyList),
	my_term_copy(Body,VarDict2,BodyCopy).


split_off_simple_guard_new([],_,[],[]).
split_off_simple_guard_new([G|Gs],VarDict,S,C) :-
	( simple_guard_new(G,VarDict) ->
		S = [G|Ss],
		split_off_simple_guard_new(Gs,VarDict,Ss,C)
	;
		S = [],
		C = [G|Gs]
	).

% simple guard: cheap and benign (does not bind variables)
simple_guard_new(G,Vars) :-
	builtin_binds_b(G,BoundVars),
	not(( member(V,BoundVars),
	      memberchk_eq(V,Vars)
	   )).

dependency_reorder(Units,NUnits) :-
	dependency_reorder(Units,[],NUnits).

dependency_reorder([],Acc,Result) :-
	reverse(Acc,Result).

dependency_reorder([Unit|Units],Acc,Result) :-
	Unit = unit(_GID,_Goal,Type,GIDs),
	( Type == fixed ->
		NAcc = [Unit|Acc]
	;
		dependency_insert(Acc,Unit,GIDs,NAcc)
	),
	dependency_reorder(Units,NAcc,Result).

dependency_insert([],Unit,_,[Unit]).
dependency_insert([X|Xs],Unit,GIDs,L) :-
	X = unit(GID,_,_,_),
	( memberchk(GID,GIDs) ->
		L = [Unit,X|Xs]
	;
		L = [X | T],
		dependency_insert(Xs,Unit,GIDs,T)
	).

build_units(Retrievals,Guard,InitialDict,Units) :-
	build_retrieval_units(Retrievals,1,N,InitialDict,Dict,Units,Tail),
	build_guard_units(Guard,N,Dict,Tail).

build_retrieval_units([],N,N,Dict,Dict,L,L).
build_retrieval_units([U|Us],N,M,Dict,NDict,L,T) :-
	term_variables(U,Vs),
	update_unit_dictionary(Vs,N,Dict,Dict1,[],GIDs),
	L = [unit(N,U,fixed,GIDs)|L1],
	N1 is N + 1,
	build_retrieval_units(Us,N1,M,Dict1,NDict,L1,T).

initialize_unit_dictionary(Term,Dict) :-
	term_variables(Term,Vars),
	pair_all_with(Vars,0,Dict).

update_unit_dictionary([],_,Dict,Dict,GIDs,GIDs).
update_unit_dictionary([V|Vs],This,Dict,NDict,GIDs,NGIDs) :-
	( lookup_eq(Dict,V,GID) ->
		( (GID == This ; memberchk(GID,GIDs) ) ->
			GIDs1 = GIDs
		;
			GIDs1 = [GID|GIDs]
		),
		Dict1 = Dict
	;
		Dict1 = [V - This|Dict],
		GIDs1 = GIDs
	),
	update_unit_dictionary(Vs,This,Dict1,NDict,GIDs1,NGIDs).

build_guard_units(Guard,N,Dict,Units) :-
	( Guard = [Goal] ->
		Units = [unit(N,Goal,fixed,[])]
	; Guard = [Goal|Goals] ->
		term_variables(Goal,Vs),
		update_unit_dictionary2(Vs,N,Dict,NDict,[],GIDs),
		Units = [unit(N,Goal,movable,GIDs)|RUnits],
		N1 is N + 1,
		build_guard_units(Goals,N1,NDict,RUnits)
	).

update_unit_dictionary2([],_,Dict,Dict,GIDs,GIDs).
update_unit_dictionary2([V|Vs],This,Dict,NDict,GIDs,NGIDs) :-
	( lookup_eq(Dict,V,GID) ->
		( (GID == This ; memberchk(GID,GIDs) ) ->
			GIDs1 = GIDs
		;
			GIDs1 = [GID|GIDs]
		),
		Dict1 = [V - This|Dict]
	;
		Dict1 = [V - This|Dict],
		GIDs1 = GIDs
	),
	update_unit_dictionary2(Vs,This,Dict1,NDict,GIDs1,NGIDs).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%  ____       _     ____                             _   _
%% / ___|  ___| |_  / ___|  ___ _ __ ___   __ _ _ __ | |_(_) ___ ___ _
%% \___ \ / _ \ __| \___ \ / _ \ '_ ` _ \ / _` | '_ \| __| |/ __/ __(_)
%%  ___) |  __/ |_   ___) |  __/ | | | | | (_| | | | | |_| | (__\__ \_
%% |____/ \___|\__| |____/ \___|_| |_| |_|\__,_|_| |_|\__|_|\___|___(_)
%%
%%  _   _       _                    ___        __
%% | | | |_ __ (_) __ _ _   _  ___  |_ _|_ __  / _| ___ _ __ ___ _ __   ___ ___
%% | | | | '_ \| |/ _` | | | |/ _ \  | || '_ \| |_ / _ \ '__/ _ \ '_ \ / __/ _ \
%% | |_| | | | | | (_| | |_| |  __/  | || | | |  _|  __/ | |  __/ | | | (_|  __/
%%  \___/|_| |_|_|\__, |\__,_|\___| |___|_| |_|_|  \___|_|  \___|_| |_|\___\___|
%%                   |_|
:- chr_constraint
	functional_dependency/4,
	get_functional_dependency/4.

:- chr_option(mode,functional_dependency(+,+,?,?)).
:- chr_option(mode,get_functional_dependency(+,+,?,?)).

allocation_occurrence(C,AO), occurrence(C,O,RuleNb,_,_) \ functional_dependency(C,RuleNb,Pattern,Key)
	<=>
		RuleNb > 1, AO > O
	|
		functional_dependency(C,1,Pattern,Key).

functional_dependency(C,RuleNb1,Pattern,Key) \ get_functional_dependency(C,RuleNb2,QPattern,QKey)
	<=>
		RuleNb2 >= RuleNb1
	|
		QPattern = Pattern, QKey = Key.
get_functional_dependency(_,_,_,_)
	<=>
		fail.

functional_dependency_analysis(Rules) :-
		( fail, chr_pp_flag(functional_dependency_analysis,on) ->
			functional_dependency_analysis_main(Rules)
		;
			true
		).

functional_dependency_analysis_main([]).
functional_dependency_analysis_main([PRule|PRules]) :-
	( discover_unique_pattern(PRule,C,RuleNb,Pattern,Key) ->
		functional_dependency(C,RuleNb,Pattern,Key)
	;
		true
	),
	functional_dependency_analysis_main(PRules).

discover_unique_pattern(PragmaRule,F/A,RuleNb,Pattern,Key) :-
	PragmaRule = pragma(Rule,_,_,Name,RuleNb),
	Rule = rule(H1,H2,Guard,_),
	( H1 = [C1],
	  H2 = [C2] ->
		true
	; H1 = [C1,C2],
	  H2 == [] ->
		true
	),
	check_unique_constraints(C1,C2,Guard,RuleNb,List),
	term_variables(C1,Vs),
	\+ (
		member(V1,Vs),
		lookup_eq(List,V1,V2),
		memberchk_eq(V2,Vs)
	),
	select_pragma_unique_variables(Vs,List,Key1),
	copy_term_nat(C1-Key1,Pattern-Key),
	functor(C1,F,A).

select_pragma_unique_variables([],_,[]).
select_pragma_unique_variables([V|Vs],List,L) :-
	( lookup_eq(List,V,_) ->
		L = T
	;
		L = [V|T]
	),
	select_pragma_unique_variables(Vs,List,T).

	% depends on functional dependency analysis
	% and shape of rule: C1 \ C2 <=> true.
set_semantics_rules(Rules) :-
	( fail, chr_pp_flag(set_semantics_rule,on) ->
		set_semantics_rules_main(Rules)
	;
		true
	).

set_semantics_rules_main([]).
set_semantics_rules_main([R|Rs]) :-
	set_semantics_rule_main(R),
	set_semantics_rules_main(Rs).

set_semantics_rule_main(PragmaRule) :-
	PragmaRule = pragma(Rule,IDs,Pragmas,_,RuleNb),
	( Rule = rule([C1],[C2],true,_),
	  IDs = ids([ID1],[ID2]),
	  \+ is_passive(RuleNb,ID1),
	  functor(C1,F,A),
	  get_functional_dependency(F/A,RuleNb,Pattern,Key),
	  copy_term_nat(Pattern-Key,C1-Key1),
	  copy_term_nat(Pattern-Key,C2-Key2),
	  Key1 == Key2 ->
		passive(RuleNb,ID2)
	;
		true
	).

check_unique_constraints(C1,C2,G,RuleNb,List) :-
	\+ any_passive_head(RuleNb),
	variable_replacement(C1-C2,C2-C1,List),
	copy_with_variable_replacement(G,OtherG,List),
	negate_b(G,NotG),
	once(entails_b(NotG,OtherG)).

	% checks for rules of the shape ...,C1,C2... (<|=)=> ...
	% where C1 and C2 are symmteric constraints
symmetry_analysis(Rules) :-
	( chr_pp_flag(check_unnecessary_active,off) ->
		true
	;
		symmetry_analysis_main(Rules)
	).

symmetry_analysis_main([]).
symmetry_analysis_main([R|Rs]) :-
	R = pragma(Rule,ids(IDs1,IDs2),_,_,RuleNb),
	Rule = rule(H1,H2,_,_),
	( ( \+ chr_pp_flag(check_unnecessary_active,simplification) ; H2 == [] ), H1 \== [] ->
		symmetry_analysis_heads_simplification(H1,IDs1,[],[],Rule,RuleNb),
		symmetry_analysis_heads_propagation(H2,IDs2,[],[],Rule,RuleNb)
	;
		true
	),
	symmetry_analysis_main(Rs).

symmetry_analysis_heads_simplification([],[],_,_,_,_).
symmetry_analysis_heads_simplification([H|Hs],[ID|IDs],PreHs,PreIDs,Rule,RuleNb) :-
	( \+ is_passive(RuleNb,ID),
	  member2(PreHs,PreIDs,PreH-PreID),
	  \+ is_passive(RuleNb,PreID),
	  variable_replacement(PreH,H,List),
	  copy_with_variable_replacement(Rule,Rule2,List),
	  identical_guarded_rules(Rule,Rule2) ->
		passive(RuleNb,ID)
	;
		true
	),
	symmetry_analysis_heads_simplification(Hs,IDs,[H|PreHs],[ID|PreIDs],Rule,RuleNb).

symmetry_analysis_heads_propagation([],[],_,_,_,_).
symmetry_analysis_heads_propagation([H|Hs],[ID|IDs],PreHs,PreIDs,Rule,RuleNb) :-
	( \+ is_passive(RuleNb,ID),
	  member2(PreHs,PreIDs,PreH-PreID),
	  \+ is_passive(RuleNb,PreID),
	  variable_replacement(PreH,H,List),
	  copy_with_variable_replacement(Rule,Rule2,List),
	  identical_rules(Rule,Rule2) ->
		passive(RuleNb,ID)
	;
		true
	),
	symmetry_analysis_heads_propagation(Hs,IDs,[H|PreHs],[ID|PreIDs],Rule,RuleNb).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%  ____  _                 _ _  __ _           _   _
%% / ___|(_)_ __ ___  _ __ | (_)/ _(_) ___ __ _| |_(_) ___  _ __
%% \___ \| | '_ ` _ \| '_ \| | | |_| |/ __/ _` | __| |/ _ \| '_ \
%%  ___) | | | | | | | |_) | | |  _| | (_| (_| | |_| | (_) | | | |
%% |____/|_|_| |_| |_| .__/|_|_|_| |_|\___\__,_|\__|_|\___/|_| |_|
%%                   |_|
%% {{{

simplification_code(Head,ID,RestHeads,RestIDs,PragmaRule,Symbol,O,Id,L,T) :-
	PragmaRule = pragma(Rule,_,Pragmas,_,RuleNb),
	head_info1(Head,Symbol,_Vars,Susp,HeadVars,HeadPairs),
	build_head(Symbol,Id,HeadVars,ClauseHead),
	get_constraint_mode(Symbol,Mode),
	head_arg_matches(HeadPairs,Mode,[],FirstMatching,VarDict1,[],GroundVars),


	guard_splitting(Rule,GuardList0),
	( is_stored_in_guard(Symbol, RuleNb) ->
		GuardList = [Hole1|GuardList0]
	;
		GuardList = GuardList0
	),
	guard_via_reschedule_new(RestHeads,GuardList,Head,GuardCopyList,GetRestHeads,RescheduledTest),

	rest_heads_retrieval_and_matching(RestHeads,RestIDs,Head,GetRestHeads,Susps,VarDict1,VarDict,[],[],[],GroundVars,_),

	guard_body_copies3(Rule,GuardList,VarDict,GuardCopyList,BodyCopy),

	( is_stored_in_guard(Symbol, RuleNb) ->
		gen_occ_allocation_in_guard(Symbol,O,Vars,Susp,Allocation),
		gen_uncond_attach_goal(Symbol,Susp,Vars,Attachment,_),
		GuardCopyList = [Hole1Copy|_],
		Hole1Copy = (Allocation, Attachment)
	;
		true
	),


	partner_constraint_detachments(Susps,RestHeads,VarDict,SuspsDetachments),
	active_constraint_detachment(Id,Susp,Head,VarDict,SuspDetachment),

	( chr_pp_flag(debugable,on) ->
		Rule = rule(_,_,Guard,Body),
		my_term_copy(Guard - Body, VarDict, DebugGuard - DebugBody),
		sort_by_key([Susp|Susps],[ID|RestIDs],SortedSusps),
		DebugTry   = 'chr debug_event'(  try(SortedSusps,[],DebugGuard,DebugBody)),
		DebugApply = 'chr debug_event'(apply(SortedSusps,[],DebugGuard,DebugBody)),
		instrument_goal(ActualCut,DebugTry,DebugApply,Cut)
	;
		Cut = ActualCut
	),
	actual_cut(Symbol,O,ActualCut),
	Clause = ( ClauseHead :-
			FirstMatching,
			RescheduledTest,
			Cut,
			SuspsDetachments,
			SuspDetachment,
			BodyCopy
		),
	add_location(Clause,RuleNb,LocatedClause),
	L = [LocatedClause | T].

actual_cut(Symbol,Occurrence,ActualCut) :-
	( unconditional_occurrence(Symbol,Occurrence),
          chr_pp_flag(late_allocation,on) ->
		ActualCut = true
	;
		ActualCut = (!)
	).
% }}}

add_location(Clause,RuleNb,NClause) :-
	( chr_pp_flag(line_numbers,on) ->
		get_chr_source_file(File),
		get_line_number(RuleNb,LineNb),
		NClause = '$source_location'(File,LineNb):Clause
	;
		NClause = Clause
	).

add_dummy_location(Clause,NClause) :-
	( chr_pp_flag(line_numbers,on) ->
		get_chr_source_file(File),
		NClause = '$source_location'(File,1):Clause
	;
		NClause = Clause
	).
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	head_arg_matches(+Pairs,+Modes,+VarDict,-Goal,-NVarDict) is det.
%
%	Return goal matching newly introduced variables with variables in
%	previously looked-up heads.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
head_arg_matches(Pairs,Modes,VarDict,Goal,NVarDict) :-
	head_arg_matches(Pairs,Modes,VarDict,Goal,NVarDict,[],_).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	head_arg_matches(+Pairs,+Modes,+VarDict,-Goal,-NVarDict,+GroundVars,-NGroundVars) is det.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
head_arg_matches(Pairs,Modes,VarDict,Goal,NVarDict,GroundVars,NGroundVars) :-
	head_arg_matches_(Pairs,Modes,VarDict,GroundVars,GoalList,NVarDict,NGroundVars),
	list2conj(GoalList,Goal).

head_arg_matches_([],[],VarDict,GroundVars,[],VarDict,GroundVars).
head_arg_matches_([silent(Arg-Var)| Rest],[Mode|Modes],VarDict,GroundVars,GoalList,NVarDict,NGroundVars) :- !,
	( Mode == (+) ->
		term_variables(Arg,GroundVars0,GroundVars),
		head_arg_matches_(Rest,Modes,VarDict,GroundVars0,GoalList,NVarDict,NGroundVars)
	;
		head_arg_matches_(Rest,Modes,VarDict,GroundVars,GoalList,NVarDict,NGroundVars)
	).
head_arg_matches_([Arg-Var| Rest],[Mode|Modes],VarDict,GroundVars,GoalList,NVarDict,NGroundVars) :-
	( var(Arg) ->
		( lookup_eq(VarDict,Arg,OtherVar) ->
			( Mode = (+) ->
				( memberchk_eq(Arg,GroundVars) ->
					GoalList = [Var = OtherVar | RestGoalList],
					GroundVars1 = GroundVars
				;
					GoalList = [Var == OtherVar | RestGoalList],
					GroundVars1 = [Arg|GroundVars]
				)
		        ;
				GoalList = [Var == OtherVar | RestGoalList],
				GroundVars1 = GroundVars
		        ),
			VarDict1 = VarDict
		;
			VarDict1 = [Arg-Var | VarDict],
			GoalList = RestGoalList,
			( Mode = (+) ->
				GroundVars1 = [Arg|GroundVars]
			;
				GroundVars1 = GroundVars
			)
		),
		Pairs = Rest,
		RestModes = Modes
	; ground(Arg), Arg = '$chr_identifier_match'(ActualArg,IndexType) ->
	    identifier_label_atom(IndexType,Var,ActualArg,Goal),
	    GoalList = [Goal|RestGoalList],
	    VarDict = VarDict1,
	    GroundVars1 = GroundVars,
	    Pairs = Rest,
	    RestModes = Modes
	; atomic(Arg) ->
	    ( Mode = (+) ->
	            GoalList = [ Var = Arg | RestGoalList]
	    ;
	            GoalList = [ Var == Arg | RestGoalList]
	    ),
	    VarDict = VarDict1,
	    GroundVars1 = GroundVars,
	    Pairs = Rest,
	    RestModes = Modes
	; Mode == (+), is_ground(GroundVars,Arg)  ->
	    copy_with_variable_replacement(Arg,ArgCopy,VarDict),
	    GoalList = [ Var = ArgCopy | RestGoalList],
	    VarDict = VarDict1,
	    GroundVars1 = GroundVars,
	    Pairs = Rest,
	    RestModes = Modes
	; Mode == (?), is_ground(GroundVars,Arg)  ->
	    copy_with_variable_replacement(Arg,ArgCopy,VarDict),
	    GoalList = [ Var == ArgCopy | RestGoalList],
	    VarDict = VarDict1,
	    GroundVars1 = GroundVars,
	    Pairs = Rest,
	    RestModes = Modes
	;   Arg =.. [_|Args],
	    functor(Arg,Fct,N),
	    functor(Term,Fct,N),
	    Term =.. [_|Vars],
	    ( Mode = (+) ->
		GoalList = [ Var = Term | RestGoalList ]
	    ;
		GoalList = [ nonvar(Var), Var = Term | RestGoalList ]
	    ),
	    pairup(Args,Vars,NewPairs),
	    append(NewPairs,Rest,Pairs),
	    replicate(N,Mode,NewModes),
	    append(NewModes,Modes,RestModes),
	    VarDict1 = VarDict,
	    GroundVars1 = GroundVars
	),
	head_arg_matches_(Pairs,RestModes,VarDict1,GroundVars1,RestGoalList,NVarDict,NGroundVars).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
% add_heads_types(+ListOfHeads,+VarTypes,-NVarTypes) is det.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
add_heads_types([],VarTypes,VarTypes).
add_heads_types([Head|Heads],VarTypes,NVarTypes) :-
	add_head_types(Head,VarTypes,VarTypes1),
	add_heads_types(Heads,VarTypes1,NVarTypes).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
% add_head_types(+Head,+VarTypes,-NVarTypes) is det.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
add_head_types(Head,VarTypes,NVarTypes) :-
	functor(Head,F,A),
	get_constraint_type_det(F/A,ArgTypes),
	Head =.. [_|Args],
	add_args_types(Args,ArgTypes,VarTypes,NVarTypes).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
% add_args_types(+Terms,+Types,+VarTypes,-NVarTypes) is det.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
add_args_types([],[],VarTypes,VarTypes).
add_args_types([Arg|Args],[Type|Types],VarTypes,NVarTypes) :-
	add_arg_types(Arg,Type,VarTypes,VarTypes1),
	add_args_types(Args,Types,VarTypes1,NVarTypes).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
% add_arg_types(+Term,+Type,+VarTypes,-NVarTypes) is det.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
% OPTIMIZATION: don't add if `any'
add_arg_types(Term,Type,VarTypes,NVarTypes) :-
	( Type == any ->
		NVarTypes = VarTypes
	; var(Term) ->
		( lookup_eq(VarTypes,Term,_) ->
			NVarTypes = VarTypes
		;
			NVarTypes = [Term-Type|VarTypes]
		)
	; % nonvar
		NVarTypes = VarTypes % approximate with any
	).



%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	add_heads_ground_variables(+ListOfHeads,+GroundVars,-NGroundVars) is det.
%
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
add_heads_ground_variables([],GroundVars,GroundVars).
add_heads_ground_variables([Head|Heads],GroundVars,NGroundVars) :-
	add_head_ground_variables(Head,GroundVars,GroundVars1),
	add_heads_ground_variables(Heads,GroundVars1,NGroundVars).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	add_head_ground_variables(+Head,+GroundVars,-GroundVars) is det.
%
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
add_head_ground_variables(Head,GroundVars,NGroundVars) :-
	functor(Head,F,A),
	get_constraint_mode(F/A,ArgModes),
	Head =.. [_|Args],
	add_arg_ground_variables(Args,ArgModes,GroundVars,NGroundVars).


add_arg_ground_variables([],[],GroundVars,GroundVars).
add_arg_ground_variables([Arg|Args],[Mode|Modes],GroundVars,NGroundVars) :-
	( Mode == (+) ->
		term_variables(Arg,Vars),
		add_var_ground_variables(Vars,GroundVars,GroundVars1)
	;
		GroundVars = GroundVars1
	),
	add_arg_ground_variables(Args,Modes,GroundVars1,NGroundVars).

add_var_ground_variables([],GroundVars,GroundVars).
add_var_ground_variables([Var|Vars],GroundVars,NGroundVars) :-
	( memberchk_eq(Var,GroundVars) ->
		GroundVars1 = GroundVars
	;
		GroundVars1 = [Var|GroundVars]
	),
	add_var_ground_variables(Vars,GroundVars1,NGroundVars).
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	is_ground(+GroundVars,+Term) is semidet.
%
%	Determine whether =Term= is always ground.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
is_ground(GroundVars,Term) :-
	( ground(Term) ->
		true
	; compound(Term) ->
		Term =.. [_|Args],
		maplist(is_ground(GroundVars),Args)
	;
		memberchk_eq(Term,GroundVars)
	).

%%	check_ground(+GroundVars,+Term,-Goal) is det.
%
%	Return runtime check to see whether =Term= is ground.
check_ground(GroundVars,Term,Goal) :-
	term_variables(Term,Variables),
	check_ground_variables(Variables,GroundVars,Goal).

check_ground_variables([],_,true).
check_ground_variables([Var|Vars],GroundVars,Goal) :-
	( memberchk_eq(Var,GroundVars) ->
		check_ground_variables(Vars,GroundVars,Goal)
	;
		Goal = (ground(Var), RGoal),
		check_ground_variables(Vars,GroundVars,RGoal)
	).

rest_heads_retrieval_and_matching(Heads,IDs,ActiveHead,GoalList,Susps,VarDict,NVarDict,PrevHs,PrevSusps,AttrDict) :-
	rest_heads_retrieval_and_matching(Heads,IDs,ActiveHead,GoalList,Susps,VarDict,NVarDict,PrevHs,PrevSusps,AttrDict,[],_).

rest_heads_retrieval_and_matching(Heads,IDs,ActiveHead,GoalList,Susps,VarDict,NVarDict,PrevHs,PrevSusps,AttrDict,GroundVars,NGroundVars) :-
	( Heads = [_|_] ->
		rest_heads_retrieval_and_matching_n(Heads,IDs,PrevHs,PrevSusps,ActiveHead,GoalList,Susps,VarDict,NVarDict,AttrDict,GroundVars,NGroundVars)
	;
		GoalList = [],
		Susps = [],
		VarDict = NVarDict,
		GroundVars = NGroundVars
	).

rest_heads_retrieval_and_matching_n([],_,_,_,_,[],[],VarDict,VarDict,_AttrDict,GroundVars,GroundVars).
rest_heads_retrieval_and_matching_n([H|Hs],[ID|IDs],PrevHs,PrevSusps,ActiveHead,
    [Goal|Goals],[Susp|Susps],VarDict,NVarDict,_AttrDict,GroundVars,NGroundVars) :-
	functor(H,F,A),
	head_info(H,A,Vars,_,_,Pairs),
	get_store_type(F/A,StoreType),
	( StoreType == default ->
		passive_head_via(H,[ActiveHead|PrevHs],VarDict,ViaGoal,VarSusps),
		delay_phase_end(validate_store_type_assumptions,
			( static_suspension_term(F/A,Suspension),
			  get_static_suspension_term_field(arguments,F/A,Suspension,Vars),
		          get_static_suspension_field(F/A,Suspension,state,active,GetState)
			)
		),
		% create_get_mutable_ref(active,State,GetMutable),
		get_constraint_mode(F/A,Mode),
		head_arg_matches(Pairs,Mode,VarDict,MatchingGoal,VarDict1,GroundVars,GroundVars1),
		NPairs = Pairs,
		sbag_member_call(Susp,VarSusps,Sbag),
		ExistentialLookup =	(
						ViaGoal,
						Sbag,
						Susp = Suspension,		% not inlined
						GetState
					),
		inline_matching_goal(MatchingGoal,MatchingGoal2)
	;
		delay_phase_end(validate_store_type_assumptions,
			( static_suspension_term(F/A,Suspension),
			  get_static_suspension_term_field(arguments,F/A,Suspension,Vars)
			)
		),
		existential_lookup(StoreType,H,[ActiveHead|PrevHs],VarDict,GroundVars,Suspension,ExistentialLookup,Susp,Pairs,NPairs),
		get_constraint_mode(F/A,Mode),
		NMode = Mode, % filter_mode(NPairs,Pairs,Mode,NMode),
		head_arg_matches(NPairs,NMode,VarDict,MatchingGoal,VarDict1,GroundVars,GroundVars1),
		filter_append(NPairs,VarDict1,DA_),		% order important here
		translate(GroundVars1,DA_,GroundVarsA),
		translate(GroundVars1,VarDict1,GroundVarsB),
		inline_matching_goal(MatchingGoal,MatchingGoal2,GroundVarsA,GroundVarsB)
	),
	different_from_other_susps(H,Susp,PrevHs,PrevSusps,DiffSuspGoals),
	Goal =
	(
		ExistentialLookup,
		DiffSuspGoals,
		MatchingGoal2
	),
	rest_heads_retrieval_and_matching_n(Hs,IDs,[H|PrevHs],[Susp|PrevSusps],ActiveHead,Goals,Susps,VarDict1,NVarDict,_NewAttrDict,GroundVars1,NGroundVars).

inline_matching_goal(G1,G2) :-
	inline_matching_goal(G1,G2,[],[]).

inline_matching_goal(A==B,true,GVA,GVB) :-
    memberchk_eq(A,GVA),
    memberchk_eq(B,GVB),
    A=B, !.
% inline_matching_goal(A=B,true,_,_) :- A=B, !.
inline_matching_goal((A,B),(A2,B2),GVA,GVB) :- !,
    inline_matching_goal(A,A2,GVA,GVB),
    inline_matching_goal(B,B2,GVA,GVB).
inline_matching_goal(X,X,_,_).


filter_mode([],_,_,[]).
filter_mode([Arg-Var|Rest],[_-V|R],[M|Ms],Modes) :-
	( Var == V ->
		Modes = [M|MT],
		filter_mode(Rest,R,Ms,MT)
	;
		filter_mode([Arg-Var|Rest],R,Ms,Modes)
	).

filter_append([],VarDict,VarDict).
filter_append([X|Xs],VarDict,NVarDict) :-
	( X = silent(_) ->
		filter_append(Xs,VarDict,NVarDict)
	;
		NVarDict = [X|NVarDict0],
		filter_append(Xs,VarDict,NVarDict0)
	).

check_unique_keys([],_).
check_unique_keys([V|Vs],Dict) :-
	lookup_eq(Dict,V,_),
	check_unique_keys(Vs,Dict).

% Generates tests to ensure the found constraint differs from previously found constraints
%	TODO: detect more cases where constraints need be different
different_from_other_susps(Head,Susp,Heads,Susps,DiffSuspGoals) :-
	different_from_other_susps_(Heads,Susps,Head,Susp,DiffSuspGoalList),
	list2conj(DiffSuspGoalList,DiffSuspGoals).

different_from_other_susps_(_,[],_,_,[]) :- !.
different_from_other_susps_([PreHead|Heads],[PreSusp|Susps],Head,Susp,List) :-
	( functor(Head,F,A), functor(PreHead,F,A),
          copy_term_nat(PreHead-Head,PreHeadCopy-HeadCopy),
	  \+ \+ PreHeadCopy = HeadCopy ->

		List = [Susp \== PreSusp | Tail]
	;
		List = Tail
	),
	different_from_other_susps_(Heads,Susps,Head,Susp,Tail).

% passive_head_via(in,in,in,in,out,out,out) :-
passive_head_via(Head,PrevHeads,VarDict,Goal,AllSusps) :-
	functor(Head,F,A),
	get_constraint_index(F/A,Pos),
	/* which static variables may contain runtime variables */
	common_variables(Head,PrevHeads,CommonVars0),
	ground_vars([Head],GroundVars),
	list_difference_eq(CommonVars0,GroundVars,CommonVars),
	/********************************************************/
	global_list_store_name(F/A,Name),
	GlobalGoal = nb_getval(Name,AllSusps),
	get_constraint_mode(F/A,ArgModes),
	( Vars == [] ->
		Goal = GlobalGoal
	; member(CommonVar,CommonVars), nth1(I,ArgModes,(-)), arg(I,Head,Arg), Arg == CommonVar ->
		translate([CommonVar],VarDict,[Var]),
		gen_get_mod_constraints(F/A,Var,AttrGoal,AllSusps),
		Goal = AttrGoal
	;
		translate(CommonVars,VarDict,Vars),
		add_heads_types(PrevHeads,[],TypeDict),
		my_term_copy(TypeDict,VarDict,TypeDictCopy),
		gen_get_mod_constraints(F/A,Vars,TypeDictCopy,ViaGoal,AttrGoal,AllSusps),
		Goal =
			( ViaGoal ->
				AttrGoal
			;
				GlobalGoal
			)
	).

common_variables(T,Ts,Vs) :-
	term_variables(T,V1),
	term_variables(Ts,V2),
	intersect_eq(V1,V2,Vs).

gen_get_mod_constraints(FA,Vars,TypeDict,ViaGoal,AttrGoal,AllSusps) :-
	via_goal(Vars,TypeDict,ViaGoal,Var),
	get_target_module(Mod),
	AttrGoal =
	(   get_attr(Var,Mod,TSusps),
	    TSuspsEqSusps % TSusps = Susps
	),
	get_max_constraint_index(N),
	( N == 1 ->
		TSuspsEqSusps = true, % TSusps = Susps
		AllSusps = TSusps
	;
		get_constraint_index(FA,Pos),
		get_suspensions(N,Pos,TSusps,TSuspsEqSusps,AllSusps)
	).
via_goal(Vars,TypeDict,ViaGoal,Var) :-
        ( Vars = [] ->
		ViaGoal = fail
	; Vars = [A] ->
		lookup_type(TypeDict,A,Type),
		( atomic_type(Type) ->
			ViaGoal = var(A),
			A = Var
		;
			ViaGoal =  'chr newvia_1'(A,Var)
		)
	; Vars = [A,B] ->
		ViaGoal = 'chr newvia_2'(A,B,Var)
        ;
		ViaGoal = 'chr newvia'(Vars,Var)
	).
lookup_type(TypeDict,Var,Type) :-
	( lookup_eq(TypeDict,Var,Type) ->
		true
	;
		Type = any % default type
	).
gen_get_mod_constraints(FA,Var,AttrGoal,AllSusps) :-
	get_target_module(Mod),
	AttrGoal =
	(   get_attr(Var,Mod,TSusps),
	    TSuspsEqSusps % TSusps = Susps
	),
	get_max_constraint_index(N),
	( N == 1 ->
		TSuspsEqSusps = true, % TSusps = Susps
		AllSusps = TSusps
	;
		get_constraint_index(FA,Pos),
		get_suspensions(N,Pos,TSusps,TSuspsEqSusps,AllSusps)
	).

guard_body_copies(Rule,VarDict,GuardCopy,BodyCopy) :-
	guard_body_copies2(Rule,VarDict,GuardCopyList,BodyCopy),
	list2conj(GuardCopyList,GuardCopy).

guard_body_copies2(Rule,VarDict,GuardCopyList,BodyCopy) :-
	Rule = rule(_,H,Guard,Body),
	conj2list(Guard,GuardList),
	split_off_simple_guard(GuardList,VarDict,GuardPrefix,RestGuardList),
	my_term_copy(GuardPrefix-RestGuardList,VarDict,VarDict2,GuardPrefixCopy-RestGuardListCopyCore),

	append(GuardPrefixCopy,[RestGuardCopy],GuardCopyList),
	term_variables(RestGuardList,GuardVars),
	term_variables(RestGuardListCopyCore,GuardCopyVars),
	% variables that are declared to be ground don't need to be locked
	ground_vars(H,GroundVars),
	list_difference_eq(GuardVars,GroundVars,LockedGuardVars),
	( chr_pp_flag(guard_locks,off) ->
		Locks = [],
		Unlocks = []
	;
          bagof(Lock - Unlock,
                X ^ Y ^ (lists:member(X,LockedGuardVars),	 % X is a variable appearing in the original guard
                     pairlist:lookup_eq(VarDict,X,Y),            % translate X into new variable
                     memberchk_eq(Y,GuardCopyVars),		 % redundant check? or multiple entries for X possible?
		     chr_lock(Y,Lock),
		     chr_unlock(Y,Unlock)
                    ),
                LocksUnlocks) ->
		once(pairup(Locks,Unlocks,LocksUnlocks))
	;
		Locks = [],
		Unlocks = []
	),
	list2conj(Locks,LockPhase),
	list2conj(Unlocks,UnlockPhase),
	list2conj(RestGuardListCopyCore,RestGuardCopyCore),
	RestGuardCopy = (LockPhase,(RestGuardCopyCore,UnlockPhase)),
	my_term_copy(Body,VarDict2,BodyCopy).


split_off_simple_guard([],_,[],[]).
split_off_simple_guard([G|Gs],VarDict,S,C) :-
	( simple_guard(G,VarDict) ->
		S = [G|Ss],
		split_off_simple_guard(Gs,VarDict,Ss,C)
	;
		S = [],
		C = [G|Gs]
	).

% simple guard: cheap and benign (does not bind variables)
simple_guard(G,VarDict) :-
	binds_b(G,Vars),
	\+ (( member(V,Vars),
	     lookup_eq(VarDict,V,_)
	   )).

active_constraint_detachment(Id,Susp,Head,VarDict,SuspDetachment) :-
	functor(Head,F,A),
	C = F/A,
	( is_stored(C) ->
		(
			(
				Id == [0], chr_pp_flag(store_in_guards, off)
			;
				( get_allocation_occurrence(C,AO),
				  get_max_occurrence(C,MO),
				  MO < AO )
			),
			only_ground_indexed_arguments(C), chr_pp_flag(late_allocation,on) ->
			SuspDetachment = true
		;
			gen_uncond_susp_detachment(Head,Susp,active,VarDict,UnCondSuspDetachment),
			( chr_pp_flag(late_allocation,on) ->
				SuspDetachment =
					( var(Susp) ->
						true
					;
						UnCondSuspDetachment
					)
			;
				SuspDetachment = UnCondSuspDetachment
			)
		)
	;
	        SuspDetachment = true
	).

partner_constraint_detachments([],[],_,true).
partner_constraint_detachments([Susp|Susps],[Head|Heads],VarDict,(SuspDetachment,SuspsDetachments)) :-
   gen_uncond_susp_detachment(Head,Susp,partner,VarDict,SuspDetachment),
   partner_constraint_detachments(Susps,Heads,VarDict,SuspsDetachments).

gen_uncond_susp_detachment(Head,Susp,Role,VarDict,SuspDetachment) :-
	functor(Head,F,A),
	C = F/A,
	( is_stored(C) ->
	     SuspDetachment = ( DebugEvent, RemoveInternalGoal),
	     ( chr_pp_flag(debugable,on) ->
		DebugEvent = 'chr debug_event'(remove(Susp))
	     ;
		DebugEvent = true
	     ),
	     remove_constraint_goal(C,Susp,Vars,true,(DeleteCall,Detach),Role,RemoveInternalGoal),
	     delete_constraint_goal(Head,Susp,VarDict,DeleteCall),
	     ( \+ only_ground_indexed_arguments(C), \+ get_store_type(C,var_assoc_store(_,_)) ->
		detach_constraint_atom(C,Vars,Susp,Detach)
	     ;
		Detach = true
	     )
	;
	     SuspDetachment = true
	).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%  ____  _                                   _   _               _
%% / ___|(_)_ __ ___  _ __   __ _  __ _  __ _| |_(_) ___  _ __   / |
%% \___ \| | '_ ` _ \| '_ \ / _` |/ _` |/ _` | __| |/ _ \| '_ \  | |
%%  ___) | | | | | | | |_) | (_| | (_| | (_| | |_| | (_) | | | | | |
%% |____/|_|_| |_| |_| .__/ \__,_|\__, |\__,_|\__|_|\___/|_| |_| |_|
%%                   |_|          |___/
%% {{{

simpagation_head1_code(Head,ID,RestHeads,OtherIDs,PragmaRule,F/A,O,Id,L,T) :-
	PragmaRule = pragma(Rule,ids(_,Heads2IDs),Pragmas,_Name,RuleNb),
	Rule = rule(_Heads,Heads2,Guard,Body),

	head_info(Head,A,Vars,Susp,HeadVars,HeadPairs),
	get_constraint_mode(F/A,Mode),
	head_arg_matches(HeadPairs,Mode,[],FirstMatching,VarDict1,[],GroundVars),

	build_head(F,A,Id,HeadVars,ClauseHead),

	append(RestHeads,Heads2,Heads),
	append(OtherIDs,Heads2IDs,IDs),
	reorder_heads(RuleNb,Head,Heads,IDs,NHeads,NIDs),

	guard_splitting(Rule,GuardList0),
	( is_stored_in_guard(F/A, RuleNb) ->
		GuardList = [Hole1|GuardList0]
	;
		GuardList = GuardList0
	),
	guard_via_reschedule_new(NHeads,GuardList,Head,GuardCopyList,GetRestHeads,RescheduledTest),

	rest_heads_retrieval_and_matching(NHeads,NIDs,Head,GetRestHeads,Susps,VarDict1,VarDict,[],[],[],GroundVars,_),
	split_by_ids(NIDs,Susps,OtherIDs,Susps1,Susps1IDs,Susps2,Susps2IDs),

	guard_body_copies3(Rule,GuardList,VarDict,GuardCopyList,BodyCopy),

	( is_stored_in_guard(F/A, RuleNb) ->
		gen_uncond_attach_goal(F/A,Susp,Vars,Attachment,_),
		GuardCopyList = [Hole1Copy|_],
		Hole1Copy = Attachment
	;
		true
	),

	sort_by_key(Susps1,Susps1IDs,SortedSusps1),
	partner_constraint_detachments(SortedSusps1,RestHeads,VarDict,SuspsDetachments),
	active_constraint_detachment(Id,Susp,Head,VarDict,SuspDetachment),

	( chr_pp_flag(debugable,on) ->
		my_term_copy(Guard - Body, VarDict, DebugGuard - DebugBody),
		sort_by_key([Susp|Susps1],[ID|Susps1IDs],RemovedSusps),
		sort_by_key(Susps2,Susps2IDs,KeptSusps),
		DebugTry   = 'chr debug_event'(  try(RemovedSusps,KeptSusps,DebugGuard,DebugBody)),
		DebugApply = 'chr debug_event'(apply(RemovedSusps,KeptSusps,DebugGuard,DebugBody)),
		instrument_goal((!),DebugTry,DebugApply,Cut)
	;
		Cut = (!)
	),

   Clause = ( ClauseHead :-
		FirstMatching,
		RescheduledTest,
		Cut,
                SuspsDetachments,
                SuspDetachment,
                BodyCopy
            ),
	add_location(Clause,RuleNb,LocatedClause),
	L = [LocatedClause | T].

% }}}

split_by_ids([],[],_,[],[]).
split_by_ids([I|Is],[S|Ss],I1s,S1s,S2s) :-
	( memberchk_eq(I,I1s) ->
		S1s = [S | R1s],
		S2s = R2s
	;
		S1s = R1s,
		S2s = [S | R2s]
	),
	split_by_ids(Is,Ss,I1s,R1s,R2s).

split_by_ids([],[],_,[],[],[],[]).
split_by_ids([I|Is],[S|Ss],I1s,S1s,SI1s,S2s,SI2s) :-
	( memberchk_eq(I,I1s) ->
		S1s  = [S | R1s],
		SI1s = [I|RSI1s],
		S2s = R2s,
		SI2s = RSI2s
	;
		S1s = R1s,
		SI1s = RSI1s,
		S2s = [S | R2s],
		SI2s = [I|RSI2s]
	),
	split_by_ids(Is,Ss,I1s,R1s,RSI1s,R2s,RSI2s).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%  ____  _                                   _   _               ____
%% / ___|(_)_ __ ___  _ __   __ _  __ _  __ _| |_(_) ___  _ __   |___ \
%% \___ \| | '_ ` _ \| '_ \ / _` |/ _` |/ _` | __| |/ _ \| '_ \    __) |
%%  ___) | | | | | | | |_) | (_| | (_| | (_| | |_| | (_) | | | |  / __/
%% |____/|_|_| |_| |_| .__/ \__,_|\__, |\__,_|\__|_|\___/|_| |_| |_____|
%%                   |_|          |___/

%% Genereate prelude + worker predicate
%% prelude calls worker
%% worker iterates over one type of removed constraints
simpagation_head2_code(Head2,ID,RestHeads2,RestIDs,PragmaRule,FA,O,Id,L,T) :-
   PragmaRule = pragma(Rule,ids(IDs1,IDs2),Pragmas,_Name,RuleNb),
   Rule = rule(Heads1,_,Guard,Body),
   append(Heads1,RestHeads2,Heads),
   append(IDs1,RestIDs,IDs),
   reorder_heads(RuleNb,Head2,Heads,IDs,[NHead|NHeads],[NID|NIDs]),
   simpagation_head2_prelude(Head2,NHead,[NHeads,Guard,Body],FA,O,Id,L,L1),
   extend_id(Id,Id1),
   ( memberchk_eq(NID,IDs2) ->
        simpagation_universal_searches(NHeads,NIDs,IDs2,[NHead,Head2],Rule,FA,O,NextHeads,PreHeads,NextIDs,Id1,Id2,L1,L2)
   ;
	L1 = L2, Id1 = Id2,NextHeads = NHeads, PreHeads = [NHead,Head2], NextIDs = NIDs
   ),
   universal_search_iterator_end(PreHeads,NextHeads,Rule,FA,O,Id2,L2,L3),
   simpagation_head2_worker(PreHeads,NextHeads,NextIDs,ID,PragmaRule,FA,O,Id2,L3,T).

simpagation_universal_searches([],[],_,PreHeads,_,_,_,[],PreHeads,[],Id,Id,L,L).
simpagation_universal_searches(Heads,[ID|IDs],IDs2,PreHeads,Rule,C,O,OutHeads,OutPreHeads,OutIDs,Id,NId,L,T) :-
	Heads = [Head|RHeads],
	inc_id(Id,Id1),
	universal_search_iterator_end(PreHeads,Heads,Rule,C,O,Id,L,L0),
	universal_search_iterator(Heads,PreHeads,Rule,C,O,Id,L0,L1),
	( memberchk_eq(ID,IDs2) ->
		simpagation_universal_searches(RHeads,IDs,IDs2,[Head|PreHeads],Rule,C,O,OutHeads,OutPreHeads,OutIDs,Id1,NId,L1,T)
	;
		NId = Id1, L1 = T, OutHeads = RHeads, OutPreHeads = [Head|PreHeads], IDs = OutIDs
	).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
simpagation_head2_prelude(Head,Head1,Rest,F/A,O,Id1,L,T) :-
	head_info(Head,A,Vars,Susp,VarsSusp,HeadPairs),
	build_head(F,A,Id1,VarsSusp,ClauseHead),
	get_constraint_mode(F/A,Mode),
	head_arg_matches(HeadPairs,Mode,[],FirstMatching,VarDict,[],GroundVars),

	lookup_passive_head(Head1,[Head],VarDict,GroundVars,ModConstraintsGoal,AllSusps),

	gen_occ_allocation(F/A,O,Vars,Susp,ConstraintAllocationGoal),

	extend_id(Id1,DelegateId),
	extra_active_delegate_variables(Head,[Head1|Rest],VarDict,ExtraVars),
	append([AllSusps|VarsSusp],ExtraVars,DelegateCallVars),
	build_head(F,A,[O|DelegateId],DelegateCallVars,Delegate),

	PreludeClause =
	   ( ClauseHead :-
	          FirstMatching,
	          ModConstraintsGoal,
	          !,
	          ConstraintAllocationGoal,
	          Delegate
	   ),
	add_dummy_location(PreludeClause,LocatedPreludeClause),
	L = [LocatedPreludeClause|T].

extra_active_delegate_variables(Term,Terms,VarDict,Vars) :-
	Term =.. [_|Args],
	delegate_variables(Term,Terms,VarDict,Args,Vars).

passive_delegate_variables(Term,PrevTerms,NextTerms,VarDict,Vars) :-
	term_variables(PrevTerms,PrevVars),
	delegate_variables(Term,NextTerms,VarDict,PrevVars,Vars).

delegate_variables(Term,Terms,VarDict,PrevVars,Vars) :-
	term_variables(Term,V1),
	term_variables(Terms,V2),
	intersect_eq(V1,V2,V3),
	list_difference_eq(V3,PrevVars,V4),
	translate(V4,VarDict,Vars).


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
simpagation_head2_worker([CurrentHead|PreHeads],NextHeads,NextIDs,ID,PragmaRule,F/A,O,Id,L,T) :-
	PragmaRule = pragma(Rule,ids(IDs1,_),Pragmas,_,RuleNb),
	Rule = rule(_,_,Guard,Body),
	get_prop_inner_loop_vars(PreHeads,[CurrentHead,NextHeads,Guard,Body],PreVarsAndSusps,VarDict,Susp,Vars,PreSusps),

	gen_var(OtherSusp),
	gen_var(OtherSusps),

	functor(CurrentHead,OtherF,OtherA),
	gen_vars(OtherA,OtherVars),
	head_info(CurrentHead,OtherA,OtherVars,OtherSusp,_VarsSusp,HeadPairs),
	get_constraint_mode(OtherF/OtherA,Mode),
	head_arg_matches(HeadPairs,Mode,VarDict,FirstMatching,VarDict1,[],GroundVars),

	delay_phase_end(validate_store_type_assumptions,
		( static_suspension_term(OtherF/OtherA,OtherSuspension),
		  get_static_suspension_field(OtherF/OtherA,OtherSuspension,state,active,GetState),
		  get_static_suspension_term_field(arguments,OtherF/OtherA,OtherSuspension,OtherVars)
		)
	),
	% create_get_mutable_ref(active,State,GetMutable),
	different_from_other_susps(CurrentHead,OtherSusp,PreHeads,PreSusps,DiffSuspGoals),
	CurrentSuspTest = (
	   OtherSusp = OtherSuspension,
	   GetState,
	   DiffSuspGoals,
	   FirstMatching
	),

	ClauseVars = [[OtherSusp|OtherSusps]|PreVarsAndSusps],
	build_head(F,A,[O|Id],ClauseVars,ClauseHead),

	guard_splitting(Rule,GuardList0),
	( is_stored_in_guard(F/A, RuleNb) ->
		GuardList = [Hole1|GuardList0]
	;
		GuardList = GuardList0
	),
	guard_via_reschedule_new(NextHeads,GuardList,[CurrentHead|PreHeads],GuardCopyList,RestSuspsRetrieval,RescheduledTest),

	rest_heads_retrieval_and_matching(NextHeads,NextIDs,[CurrentHead|PreHeads],RestSuspsRetrieval,Susps,VarDict1,VarDict2,[CurrentHead|PreHeads],[OtherSusp|PreSusps],[]),
	split_by_ids(NextIDs,Susps,IDs1,Susps1,Susps2),
	split_by_ids(NextIDs,NextHeads,IDs1,RestHeads1,_),

	partner_constraint_detachments([OtherSusp | Susps1],[CurrentHead|RestHeads1],VarDict2,Susps1Detachments),

	RecursiveVars = [OtherSusps|PreVarsAndSusps],
	build_head(F,A,[O|Id],RecursiveVars,RecursiveCall),
	RecursiveVars2 = [[]|PreVarsAndSusps],
	build_head(F,A,[O|Id],RecursiveVars2,RecursiveCall2),

	guard_body_copies3(Rule,GuardList,VarDict2,GuardCopyList,BodyCopy),
	( is_stored_in_guard(F/A, RuleNb) ->
		GuardCopyList = [GuardAttachment|_] % once( ) ??
	;
		true
	),

	( is_observed(F/A,O) ->
	    gen_uncond_attach_goal(F/A,Susp,Vars,Attachment,Generation),
	    gen_state_cond_call(Susp,F/A,RecursiveCall,Generation,ConditionalRecursiveCall),
	    gen_state_cond_call(Susp,F/A,RecursiveCall2,Generation,ConditionalRecursiveCall2)
	;
	    Attachment = true,
	    ConditionalRecursiveCall = RecursiveCall,
	    ConditionalRecursiveCall2 = RecursiveCall2
	),

	( chr_pp_flag(debugable,on) ->
		my_term_copy(Guard - Body, VarDict, DebugGuard - DebugBody),
		DebugTry   = 'chr debug_event'(  try([OtherSusp|Susps1],[Susp|Susps2],DebugGuard,DebugBody)),
		DebugApply = 'chr debug_event'(apply([OtherSusp|Susps1],[Susp|Susps2],DebugGuard,DebugBody))
	;
		DebugTry = true,
		DebugApply = true
	),

	( is_stored_in_guard(F/A, RuleNb) ->
		GuardAttachment = Attachment,
		BodyAttachment = true
	;
		GuardAttachment = true,
		BodyAttachment = Attachment	% will be true if not observed at all
	),

	( member(unique(ID1,UniqueKeys), Pragmas),
	  check_unique_keys(UniqueKeys,VarDict) ->
	     Clause =
		( ClauseHead :-
			( CurrentSuspTest ->
				( RescheduledTest,
				  DebugTry ->
					DebugApply,
					Susps1Detachments,
					BodyAttachment,
					BodyCopy,
					ConditionalRecursiveCall2
				;
					RecursiveCall2
				)
			;
				RecursiveCall
			)
		)
	 ;
	     Clause =
			( ClauseHead :-
				( CurrentSuspTest,
				  RescheduledTest,
				  DebugTry ->
					DebugApply,
					Susps1Detachments,
					BodyAttachment,
					BodyCopy,
					ConditionalRecursiveCall
				;
					RecursiveCall
				)
			)
	),
	add_location(Clause,RuleNb,LocatedClause),
	L = [LocatedClause | T].

gen_state_cond_call(Susp,FA,Call,Generation,ConditionalCall) :-
	( may_trigger(FA) ->
		does_use_field(FA,generation),
		delay_phase_end(validate_store_type_assumptions,
			( static_suspension_term(FA,Suspension),
			  get_update_static_suspension_field(FA,Susp,Suspension,state,active,inactive,GetState,UpdateState),
			  get_static_suspension_field(FA,Suspension,generation,Generation,GetGeneration),
			  get_static_suspension_term_field(arguments,FA,Suspension,Args)
			)
		)
	;
		delay_phase_end(validate_store_type_assumptions,
			( static_suspension_term(FA,Suspension),
			  get_update_static_suspension_field(FA,Susp,Suspension,state,active,inactive,GetState,UpdateState),
			  get_static_suspension_term_field(arguments,FA,Suspension,Args)
			)
		),
		GetGeneration = true
	),
	ConditionalCall =
	(	Susp = Suspension,
		GetState,
		GetGeneration ->
			UpdateState,
			Call
		;
			true
	).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%  ____                                    _   _
%% |  _ \ _ __ ___  _ __   __ _  __ _  __ _| |_(_) ___  _ __
%% | |_) | '__/ _ \| '_ \ / _` |/ _` |/ _` | __| |/ _ \| '_ \
%% |  __/| | | (_) | |_) | (_| | (_| | (_| | |_| | (_) | | | |
%% |_|   |_|  \___/| .__/ \__,_|\__, |\__,_|\__|_|\___/|_| |_|
%%                 |_|          |___/

propagation_code(Head,ID,RestHeads,RestIDs,Rule,RuleNb,FA,O,Id,L,T) :-
	( RestHeads == [] ->
		propagation_single_headed(Head,ID,Rule,RuleNb,FA,O,Id,L,T)
	;
		propagation_multi_headed(Head,RestHeads,RestIDs,Rule,RuleNb,FA,O,Id,L,T)
	).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Single headed propagation
%% everything in a single clause
propagation_single_headed(Head,ID,Rule,RuleNb,F/A,O,Id,ProgramList,ProgramTail) :-
	head_info(Head,A,Vars,Susp,VarsSusp,HeadPairs),
	build_head(F,A,Id,VarsSusp,ClauseHead),

	inc_id(Id,NextId),
	build_head(F,A,NextId,VarsSusp,NextHead),

	get_constraint_mode(F/A,Mode),
	head_arg_matches(HeadPairs,Mode,[],HeadMatching,VarDict,[],GroundVars),
	guard_body_copies(Rule,VarDict,GuardCopy,BodyCopy),

	% - recursive call -
	RecursiveCall = NextHead,

	actual_cut(F/A,O,ActualCut),

	Rule = rule(_,_,Guard,Body),
	( chr_pp_flag(debugable,on) ->
		my_term_copy(Guard - Body, VarDict, DebugGuard - DebugBody),
		DebugTry   = 'chr debug_event'(  try([],[Susp],DebugGuard,DebugBody)),
		DebugApply = 'chr debug_event'(apply([],[Susp],DebugGuard,DebugBody)),
		instrument_goal(ActualCut,DebugTry,DebugApply,Cut)
	;
		Cut = ActualCut
	),
	( may_trigger(F/A), \+ has_no_history(RuleNb)->
		use_auxiliary_predicate(novel_production),
		use_auxiliary_predicate(extend_history),
		does_use_history(F/A,O),
		gen_occ_allocation(F/A,O,Vars,Susp,Allocation),

		( named_history(RuleNb,HistoryName,HistoryIDs) ->
			( HistoryIDs == [] ->
				empty_named_history_novel_production(HistoryName,NovelProduction),
				empty_named_history_extend_history(HistoryName,ExtendHistory)
			;
				Tuple = HistoryName
			)
		;
			Tuple = RuleNb
		),

		( var(NovelProduction) ->
			NovelProduction = '$novel_production'(Susp,Tuple),
			ExtendHistory   = '$extend_history'(Susp,Tuple)
		;
			true
		),

		( is_observed(F/A,O) ->
			gen_uncond_attach_goal(F/A,Susp,Vars,Attachment,Generation),
			gen_state_cond_call(Susp,F/A,RecursiveCall,Generation,ConditionalRecursiveCall)
		;
			Attachment = true,
			ConditionalRecursiveCall = RecursiveCall
		)
	;
		Allocation = true,
		NovelProduction = true,
		ExtendHistory   = true,

		( is_observed(F/A,O) ->
			get_allocation_occurrence(F/A,AllocO),
			( O == AllocO ->
				gen_insert_constraint_internal_goal(F/A,Attachment,VarsSusp,Vars,Susp),
				Generation = 0
			;	% more room for improvement?
				Attachment = (Attachment1, Attachment2),
				gen_occ_allocation(F/A,O,Vars,Susp,Attachment1),
				gen_uncond_attach_goal(F/A,Susp,Vars,Attachment2,Generation)
			),
			gen_state_cond_call(Susp,F/A,RecursiveCall,Generation,ConditionalRecursiveCall)
		;
			gen_occ_allocation(F/A,O,Vars,Susp,Attachment),
			ConditionalRecursiveCall = RecursiveCall
		)
	),

	( is_stored_in_guard(F/A, RuleNb) ->
		GuardAttachment = Attachment,
		BodyAttachment = true
	;
		GuardAttachment = true,
		BodyAttachment = Attachment	% will be true if not observed at all
	),

	Clause = (
	     ClauseHead :-
		HeadMatching,
		Allocation,
		NovelProduction,
		GuardAttachment,
		GuardCopy,
		Cut,
		ExtendHistory,
		BodyAttachment,
		BodyCopy,
		ConditionalRecursiveCall
	),
	add_location(Clause,RuleNb,LocatedClause),
	ProgramList = [LocatedClause | ProgramTail].

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% multi headed propagation
%% prelude + predicates to accumulate the necessary combinations of suspended
%% constraints + predicate to execute the body
propagation_multi_headed(Head,RestHeads,RestIDs,Rule,RuleNb,FA,O,Id,L,T) :-
   RestHeads = [First|Rest],
   propagation_prelude(Head,RestHeads,Rule,FA,O,Id,L,L1),
   extend_id(Id,ExtendedId),
   propagation_nested_code(Rest,[First,Head],RestIDs,Rule,RuleNb,FA,O,ExtendedId,L1,T).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
propagation_prelude(Head,[First|Rest],Rule,F/A,O,Id,L,T) :-
	head_info(Head,A,Vars,Susp,VarsSusp,HeadPairs),
	build_head(F,A,Id,VarsSusp,PreludeHead),
	get_constraint_mode(F/A,Mode),
	head_arg_matches(HeadPairs,Mode,[],FirstMatching,VarDict,[],GroundVars),
	Rule = rule(_,_,Guard,Body),
	extra_active_delegate_variables(Head,[First,Rest,Guard,Body],VarDict,ExtraVars),

	lookup_passive_head(First,[Head],VarDict,GroundVars,FirstSuspGoal,Susps),

	gen_occ_allocation(F/A,O,Vars,Susp,CondAllocation),

	extend_id(Id,NestedId),
	append([Susps|VarsSusp],ExtraVars,NestedVars),
	build_head(F,A,[O|NestedId],NestedVars,NestedHead),
	NestedCall = NestedHead,

	Prelude = (
	   PreludeHead :-
	       FirstMatching,
	       FirstSuspGoal,
	       !,
	       CondAllocation,
	       NestedCall
	),
	add_dummy_location(Prelude,LocatedPrelude),
	L = [LocatedPrelude|T].

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
propagation_nested_code([],[CurrentHead|PreHeads],RestIDs,Rule,RuleNb,FA,O,Id,L,T) :-
   universal_search_iterator_end([CurrentHead|PreHeads],[],Rule,FA,O,Id,L,L1),
   propagation_body(CurrentHead,PreHeads,RestIDs,Rule,RuleNb,FA,O,Id,L1,T).

propagation_nested_code([Head|RestHeads],PreHeads,RestIDs,Rule,RuleNb,FA,O,Id,L,T) :-
   universal_search_iterator_end(PreHeads,[Head|RestHeads],Rule,FA,O,Id,L,L1),
   universal_search_iterator([Head|RestHeads],PreHeads,Rule,FA,O,Id,L1,L2),
   inc_id(Id,IncId),
   propagation_nested_code(RestHeads,[Head|PreHeads],RestIDs,Rule,RuleNb,FA,O,IncId,L2,T).

%check_fd_lookup_condition(_,_,_,_) :- fail.
check_fd_lookup_condition(F,A,_,_) :-
	get_store_type(F/A,global_singleton), !.
check_fd_lookup_condition(F,A,CurrentHead,PreHeads) :-
	\+ may_trigger(F/A),
	get_functional_dependency(F/A,1,P,K),
	copy_term(P-K,CurrentHead-Key),
	term_variables(PreHeads,PreVars),
	intersect_eq(Key,PreVars,Key),!.

propagation_body(CurrentHead,PreHeads,RestIDs,Rule,RuleNb,F/A,O,Id,L,T) :-
	Rule = rule(_,H2,Guard,Body),
	gen_var_susp_list_for_b(PreHeads,[CurrentHead,Guard,Body],VarDict1,PreVarsAndSuspsList,FirstVarsSusp,AllSusps,PrevIterators),
	flatten(PreVarsAndSuspsList,PreVarsAndSusps),
	init(AllSusps,RestSusps),
	last(AllSusps,Susp),
	gen_var(OtherSusp),
	gen_var(OtherSusps),
	functor(CurrentHead,OtherF,OtherA),
	gen_vars(OtherA,OtherVars),
	delay_phase_end(validate_store_type_assumptions,
		( static_suspension_term(OtherF/OtherA,Suspension),
		  get_static_suspension_field(OtherF/OtherA,Suspension,state,active,GetState),
		  get_static_suspension_term_field(arguments,OtherF/OtherA,Suspension,OtherVars)
		)
	),
	% create_get_mutable_ref(active,State,GetMutable),
	CurrentSuspTest = (
	   OtherSusp = Suspension,
	   GetState
	),
	ClauseVars = [[OtherSusp|OtherSusps]|PreVarsAndSusps],
	build_head(F,A,[O|Id],ClauseVars,ClauseHead),
	( check_fd_lookup_condition(OtherF,OtherA,CurrentHead,PreHeads) ->	% iterator (OtherSusps) is empty at runtime
		universal_search_iterator_failure_vars(PreHeads,Id,PreVarsAndSuspsList,FirstVarsSusp,PrevIterators,PreVarsAndSusps1,PrevId0),
		RecursiveVars = PreVarsAndSusps1
	;
		RecursiveVars = [OtherSusps|PreVarsAndSusps],
		PrevId0 = Id
	),
	( PrevId0 = [_] ->
		PrevId = PrevId0
	;
		PrevId = [O|PrevId0]
	),
	build_head(F,A,PrevId,RecursiveVars,RecursiveHead),
	RecursiveCall = RecursiveHead,
	CurrentHead =.. [_|OtherArgs],
	pairup(OtherArgs,OtherVars,OtherPairs),
	get_constraint_mode(OtherF/OtherA,Mode),
	head_arg_matches(OtherPairs,Mode,VarDict1,Matching,VarDict),

	different_from_other_susps(CurrentHead,OtherSusp,PreHeads,RestSusps,DiffSuspGoals),
	guard_body_copies(Rule,VarDict,GuardCopy,BodyCopy),
	get_occurrence(F/A,O,_,ID),

	( is_observed(F/A,O) ->
	    init(FirstVarsSusp,FirstVars),
	    gen_uncond_attach_goal(F/A,Susp,FirstVars,Attachment,Generation),
	    gen_state_cond_call(Susp,F/A,RecursiveCall,Generation,ConditionalRecursiveCall)
	;
	    Attachment = true,
	    ConditionalRecursiveCall = RecursiveCall
	),
	( (is_least_occurrence(RuleNb) ; has_no_history(RuleNb)) ->
		NovelProduction = true,
		ExtendHistory   = true
	; \+ may_trigger(F/A), maplist(is_passive(RuleNb),RestIDs) ->
		NovelProduction = true,
		ExtendHistory   = true
	;
		get_occurrence(F/A,O,_,ID),
		use_auxiliary_predicate(novel_production),
		use_auxiliary_predicate(extend_history),
		does_use_history(F/A,O),
		( named_history(RuleNb,HistoryName,HistoryIDs) ->
			( HistoryIDs == [] ->
				empty_named_history_novel_production(HistoryName,NovelProduction),
				empty_named_history_extend_history(HistoryName,ExtendHistory)
			;
				reverse([OtherSusp|RestSusps],NamedSusps),
				named_history_susps(HistoryIDs,[ID|RestIDs],[Susp|NamedSusps],HistorySusps),
				HistorySusps = [HistorySusp|_],

				( length(HistoryIDs, 1) ->
					ExtendHistory = '$extend_history'(HistorySusp,HistoryName),
					NovelProduction = '$novel_production'(HistorySusp,HistoryName)
				;
					findall(ConstraintSymbol,(member(SomeID,HistoryIDs),get_occurrence_from_id(ConstraintSymbol,_,RuleNb,SomeID)),ConstraintSymbols),
					Tuple =.. [t,HistoryName|HistorySusps]
				)
			)
		;
			HistorySusp = Susp,
			maplist(extract_symbol,H2,ConstraintSymbols),
			sort([ID|RestIDs],HistoryIDs),
			history_susps(RestIDs,[OtherSusp|RestSusps],Susp,ID,HistorySusps),
			Tuple =.. [t,RuleNb|HistorySusps]
		),

		( var(NovelProduction) ->
			novel_production_calls(ConstraintSymbols,HistoryIDs,HistorySusps,RuleNb,TupleVar,NovelProductions),
			ExtendHistory = '$extend_history'(HistorySusp,TupleVar),
			NovelProduction = ( TupleVar = Tuple, NovelProductions )
		;
			true
		)
	),


	( chr_pp_flag(debugable,on) ->
		Rule = rule(_,_,Guard,Body),
		my_term_copy(Guard - Body, VarDict, DebugGuard - DebugBody),
		get_occurrence(F/A,O,_,ID),
		sort_by_key([Susp,OtherSusp|RestSusps],[ID|RestIDs],KeptSusps),
		DebugTry   = 'chr debug_event'(  try([],KeptSusps,DebugGuard,DebugBody)),
		DebugApply = 'chr debug_event'(apply([],KeptSusps,DebugGuard,DebugBody))
	;
		DebugTry = true,
		DebugApply = true
	),

	( is_stored_in_guard(F/A, RuleNb) ->
		GuardAttachment = Attachment,
		BodyAttachment = true
	;
		GuardAttachment = true,
		BodyAttachment = Attachment	% will be true if not observed at all
	),

   Clause = (
      ClauseHead :-
	  (   CurrentSuspTest,
	     DiffSuspGoals,
             Matching,
	     NovelProduction,
	     GuardAttachment,
             GuardCopy,
	     DebugTry ->
	     DebugApply,
	     ExtendHistory,
             BodyAttachment,
             BodyCopy,
             ConditionalRecursiveCall
         ;   RecursiveCall
         )
   ),
   add_location(Clause,RuleNb,LocatedClause),
   L = [LocatedClause|T].

extract_symbol(Head,F/A) :-
	functor(Head,F,A).

novel_production_calls([],[],[],_,_,true).
novel_production_calls([ConstraintSymbol|ConstraintSymbols],[ID|IDs],[Suspension|Suspensions],RuleNb,Tuple,(Goal,Goals)) :-
	get_occurrence_from_id(ConstraintSymbol,Occurrence,RuleNb,ID),
	delay_phase_end(validate_store_type_assumptions,novel_production_call(ConstraintSymbol,Occurrence,'$novel_production'(Suspension,Tuple),Goal)),
	novel_production_calls(ConstraintSymbols,IDs,Suspensions,RuleNb,Tuple,Goals).

history_susps(RestIDs,ReversedRestSusps,Susp,ID,HistorySusps) :-
	reverse(ReversedRestSusps,RestSusps),
	sort_by_key([Susp|RestSusps],[ID|RestIDs],HistorySusps).

named_history_susps([],_,_,[]).
named_history_susps([HistoryID|HistoryIDs],IDs,Susps,[HistorySusp|HistorySusps]) :-
	select2(HistoryID,HistorySusp,IDs,Susps,RestIDs,RestSusps), !,
	named_history_susps(HistoryIDs,RestIDs,RestSusps,HistorySusps).



gen_var_susp_list_for([Head],Terms,VarDict,HeadVars,VarsSusp,Susp) :-
   !,
   functor(Head,F,A),
   head_info(Head,A,_Vars,Susp,VarsSusp,HeadPairs),
   get_constraint_mode(F/A,Mode),
   head_arg_matches(HeadPairs,Mode,[],_,VarDict),
   extra_active_delegate_variables(Head,Terms,VarDict,ExtraVars),
   append(VarsSusp,ExtraVars,HeadVars).
gen_var_susp_list_for([Head|Heads],Terms,NVarDict,VarsSusps,Rest,Susps) :-
	gen_var_susp_list_for(Heads,[Head|Terms],VarDict,Rest,_,_),
	functor(Head,F,A),
	gen_var(Susps),
	head_info(Head,A,_Vars,Susp,_VarsSusp,HeadPairs),
	get_constraint_mode(F/A,Mode),
	head_arg_matches(HeadPairs,Mode,VarDict,_,NVarDict),
	passive_delegate_variables(Head,Heads,Terms,NVarDict,HeadVars),
	append(HeadVars,[Susp,Susps|Rest],VarsSusps).

	% returns
	%	VarDict		for the copies of variables in the original heads
	%	VarsSuspsList	list of lists of arguments for the successive heads
	%	FirstVarsSusp	top level arguments
	%	SuspList	list of all suspensions
	%	Iterators	list of all iterators
gen_var_susp_list_for_b([Head],NextHeads,VarDict,[HeadVars],VarsSusp,[Susp],[]) :-
	!,
	functor(Head,F,A),
	head_info(Head,A,_Vars,Susp,VarsSusp,Pairs),			% make variables for argument positions
	get_constraint_mode(F/A,Mode),
	head_arg_matches(Pairs,Mode,[],_,VarDict),				% copy variables inside arguments, build dictionary
	extra_active_delegate_variables(Head,NextHeads,VarDict,ExtraVars),	% decide what additional variables are needed
	append(VarsSusp,ExtraVars,HeadVars).					% add additional variables to head variables
gen_var_susp_list_for_b([Head|Heads],NextHeads,NVarDict,[Vars|RestVars],FirstVarsSusp,[Susp|SuspList],[Susps|Iterators]) :-
	gen_var_susp_list_for_b(Heads,[Head|NextHeads],VarDict,RestVars,FirstVarsSusp,SuspList,Iterators),
	functor(Head,F,A),
	gen_var(Susps),
	head_info(Head,A,_Vars,Susp,_VarsSusp,HeadPairs),
	get_constraint_mode(F/A,Mode),
	head_arg_matches(HeadPairs,Mode,VarDict,_,NVarDict),
	passive_delegate_variables(Head,Heads,NextHeads,NVarDict,HeadVars),
	append(HeadVars,[Susp,Susps],Vars).

get_prop_inner_loop_vars([Head],NextHeads,HeadVars,VarDict,Susp,Vars,[]) :-
	!,
	functor(Head,F,A),
	head_info(Head,A,Vars,Susp,VarsSusp,Pairs),
	get_constraint_mode(F/A,Mode),
	head_arg_matches(Pairs,Mode,[],_,VarDict),
	extra_active_delegate_variables(Head,NextHeads,VarDict,ExtraVars),
	append(VarsSusp,ExtraVars,HeadVars).
get_prop_inner_loop_vars([Head|Heads],Terms,VarsSusps,NVarDict,MainSusp,MainVars,[Susp|RestSusps]) :-
	get_prop_inner_loop_vars(Heads,[Head|Terms],RestVarsSusp,VarDict,MainSusp,MainVars,RestSusps),
	functor(Head,F,A),
	gen_var(Susps),
	head_info(Head,A,_Vars,Susp,_VarsSusp,Pairs),
	get_constraint_mode(F/A,Mode),
	head_arg_matches(Pairs,Mode,VarDict,_,NVarDict),
	passive_delegate_variables(Head,Heads,Terms,NVarDict,HeadVars),
	append(HeadVars,[Susp,Susps|RestVarsSusp],VarsSusps).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%  ____               _             _   _                _
%% |  _ \ __ _ ___ ___(_)_   _____  | | | | ___  __ _  __| |
%% | |_) / _` / __/ __| \ \ / / _ \ | |_| |/ _ \/ _` |/ _` |
%% |  __/ (_| \__ \__ \ |\ V /  __/ |  _  |  __/ (_| | (_| |
%% |_|   \__,_|___/___/_| \_/ \___| |_| |_|\___|\__,_|\__,_|
%%
%%  ____      _        _                 _
%% |  _ \ ___| |_ _ __(_) _____   ____ _| |
%% | |_) / _ \ __| '__| |/ _ \ \ / / _` | |
%% |  _ <  __/ |_| |  | |  __/\ V / (_| | |
%% |_| \_\___|\__|_|  |_|\___| \_/ \__,_|_|
%%
%%  ____                    _           _
%% |  _ \ ___  ___  _ __ __| | ___ _ __(_)_ __   __ _
%% | |_) / _ \/ _ \| '__/ _` |/ _ \ '__| | '_ \ / _` |
%% |  _ <  __/ (_) | | | (_| |  __/ |  | | | | | (_| |
%% |_| \_\___|\___/|_|  \__,_|\___|_|  |_|_| |_|\__, |
%%                                              |___/

reorder_heads(RuleNb,Head,RestHeads,RestIDs,NRestHeads,NRestIDs) :-
	( chr_pp_flag(reorder_heads,on), length(RestHeads,Length), Length =< 6 ->
		reorder_heads_main(RuleNb,Head,RestHeads,RestIDs,NRestHeads,NRestIDs)
	;
		NRestHeads = RestHeads,
		NRestIDs = RestIDs
	).

reorder_heads_main(RuleNb,Head,RestHeads,RestIDs,NRestHeads,NRestIDs) :-
	term_variables(Head,Vars),
	InitialData = entry([],[],Vars,RestHeads,RestIDs,RuleNb),
	copy_term_nat(InitialData,InitialDataCopy),
	a_star(InitialDataCopy,FD^(chr_translate:final_data(FD)),N^EN^C^(chr_translate:expand_data(N,EN,C)),FinalData),
	InitialDataCopy = InitialData,
	FinalData   = entry(RNRestHeads,RNRestIDs,_,_,_,_),
	reverse(RNRestHeads,NRestHeads),
	reverse(RNRestIDs,NRestIDs).

final_data(Entry) :-
	Entry = entry(_,_,_,_,[],_).

expand_data(Entry,NEntry,Cost) :-
	Entry = entry(Heads,IDs,Vars,NHeads,NIDs,RuleNb),
	select2(Head1,ID1,NHeads,NIDs,NHeads1,NIDs1),
	term_variables([Head1|Vars],Vars1),
	NEntry = entry([Head1|Heads],[ID1|IDs],Vars1,NHeads1,NIDs1,RuleNb),
	order_score(Head1,ID1,Vars,NHeads1,RuleNb,Cost).

% Assigns score to head based on known variables and heads to lookup
% order_score(+head,+id,+knownvars,+heads,+rule_nb,-score). {{{
order_score(Head,ID,KnownVars,RestHeads,RuleNb,Score) :-
	functor(Head,F,A),
	get_store_type(F/A,StoreType),
	order_score(StoreType,Head,ID,KnownVars,RestHeads,RuleNb,99999,Score).
% }}}

%% order_score(+store+_type,+head,+id,+vars,+heads,+rule_nb,+score,-score) {{{
order_score(default,Head,_ID,KnownVars,RestHeads,RuleNb,CScore,NScore) :-
	term_variables(Head,HeadVars0),
	term_variables(RestHeads,RestVars),
	ground_vars([Head],GroundVars),
	list_difference_eq(HeadVars0,GroundVars,HeadVars),
	order_score_vars(HeadVars,KnownVars,RestVars,Score),
	NScore is min(CScore,Score).
order_score(multi_inthash(Indexes),Head,_ID,KnownVars,RestHeads,RuleNb,CScore,Score) :-
	( CScore =< 100 ->
		Score = CScore
	;
		order_score_indexes(Indexes,Head,KnownVars,Score)
	).
order_score(multi_hash(Indexes),Head,_ID,KnownVars,RestHeads,RuleNb,CScore,Score) :-
	( CScore =< 100 ->
		Score = CScore
	;
		order_score_indexes(Indexes,Head,KnownVars,Score)
	).
order_score(global_ground,Head,ID,KnownVars,RestHeads,RuleNb,CScore,NScore) :-
	term_variables(Head,HeadVars),
	term_variables(RestHeads,RestVars),
	order_score_vars(HeadVars,KnownVars,RestVars,Score_),
	Score is Score_ * 200,
	NScore is min(CScore,Score).
order_score(var_assoc_store(_,_),_,_,_,_,_,_,1).
order_score(global_singleton,_Head,ID,_KnownVars,_RestHeads,_RuleNb,_,Score) :-
	Score = 1.		% guaranteed O(1)
order_score(multi_store(StoreTypes),Head,ID,KnownVars,RestHeads,RuleNb,CScore,Score) :-
	multi_order_score(StoreTypes,Head,ID,KnownVars,RestHeads,RuleNb,CScore,Score).
multi_order_score([],_,_,_,_,_,Score,Score).
multi_order_score([StoreType|StoreTypes],Head,ID,KnownVars,RestHeads,RuleNb,Score0,Score) :-
	( order_score(StoreType,Head,ID,KnownVars,RestHeads,RuleNb,Score0,Score1) -> true
	; Score1 = Score0
	),
	multi_order_score(StoreTypes,Head,ID,KnownVars,RestHeads,RuleNb,Score1,Score).

order_score(identifier_store(Index),Head,ID,KnownVars,RestHeads,RuleNb,CScore,Score) :-
	arg(Index,Head,Arg),
	memberchk_eq(Arg,KnownVars),
	Score is min(CScore,10).
order_score(type_indexed_identifier_store(Index,_),Head,ID,KnownVars,RestHeads,RuleNb,CScore,Score) :-
	arg(Index,Head,Arg),
	memberchk_eq(Arg,KnownVars),
	Score is min(CScore,10).
% }}}


%% order_score_indexes(+indexes,+head,+vars,-score). {{{
order_score_indexes(Indexes,Head,Vars,Score) :-
	copy_term_nat(Head+Vars,HeadCopy+VarsCopy),
	numbervars(VarsCopy,0,_),
	order_score_indexes(Indexes,HeadCopy,Score).

order_score_indexes([I|Is],Head,Score) :-
	args(I,Head,Args),
	( maplist(ground,Args) /* forall(Arg,Args,memberchk_eq(Arg,KnownVars)) */ ->
		Score = 100
	;
		order_score_indexes(Is,Head,Score)
	).
% }}}

memberchk_eq_flip(List,Element) :- memberchk_eq(Element,List).

order_score_vars(Vars,KnownVars,RestVars,Score) :-
	order_score_count_vars(Vars,KnownVars,RestVars,K-R-O),
	( K-R-O == 0-0-0 ->
		Score = 0
	; K > 0 ->
		Score is max(10 - K,0)
	; R > 0 ->
		Score is max(10 - R,1) * 100
	;
		Score is max(10-O,1) * 1000
	).
order_score_count_vars([],_,_,0-0-0).
order_score_count_vars([V|Vs],KnownVars,RestVars,NK-NR-NO) :-
	order_score_count_vars(Vs,KnownVars,RestVars,K-R-O),
	( memberchk_eq(V,KnownVars) ->
		NK is K + 1,
		NR = R, NO = O
	; memberchk_eq(V,RestVars) ->
		NR is R + 1,
		NK = K, NO = O
	;
		NO is O + 1,
		NK = K, NR = R
	).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%  ___       _ _       _
%% |_ _|_ __ | (_)_ __ (_)_ __   __ _
%%  | || '_ \| | | '_ \| | '_ \ / _` |
%%  | || | | | | | | | | | | | | (_| |
%% |___|_| |_|_|_|_| |_|_|_| |_|\__, |
%%                              |___/

%% SWI begin
create_get_mutable_ref(V,M,GM) :- GM = (M = mutable(V)).
create_get_mutable(V,M,GM) :- M = mutable(V), GM = true.
%% SWI end

%% SICStus begin
%% create_get_mutable(V,M,GM) :- GM = get_mutable(V,M).
%% create_get_mutable_ref(V,M,GM) :- GM = get_mutable(V,M).
%% SICStus end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%  _   _ _   _ _ _ _
%% | | | | |_(_) (_) |_ _   _
%% | | | | __| | | | __| | | |
%% | |_| | |_| | | | |_| |_| |
%%  \___/ \__|_|_|_|\__|\__, |
%%                      |___/

%	Create a fresh variable.
gen_var(_).

%	Create =N= fresh variables.
gen_vars(N,Xs) :-
   length(Xs,N).

ast_head_info1(AstHead,Vars,Susp,VarsSusp,HeadPairs) :-
   AstHead = chr_constraint(_/A,Args,_),
   vars_susp(A,Vars,Susp,VarsSusp),
   pairup(Args,Vars,HeadPairs).

head_info1(Head,_/A,Vars,Susp,VarsSusp,HeadPairs) :-
   vars_susp(A,Vars,Susp,VarsSusp),
   Head =.. [_|Args],
   pairup(Args,Vars,HeadPairs).

head_info(Head,A,Vars,Susp,VarsSusp,HeadPairs) :-
   vars_susp(A,Vars,Susp,VarsSusp),
   Head =.. [_|Args],
   pairup(Args,Vars,HeadPairs).

inc_id([N|Ns],[O|Ns]) :-
   O is N + 1.
dec_id([N|Ns],[M|Ns]) :-
   M is N - 1.

extend_id(Id,[0|Id]).

next_id([_,N|Ns],[O|Ns]) :-
   O is N + 1.

	% return clause Head
	% for F/A constraint symbol, predicate identifier Id and arguments Head
build_head(F/A,Id,Args,Head) :-
	build_head(F,A,Id,Args,Head).
build_head(F,A,Id,Args,Head) :-
	buildName(F,A,Id,Name),
	( (chr_pp_flag(debugable,on) ; is_stored(F/A), ( has_active_occurrence(F/A) ; chr_pp_flag(late_allocation,off)),
	     ( may_trigger(F/A) ;
		get_allocation_occurrence(F/A,AO),
		get_max_occurrence(F/A,MO),
	     MO >= AO ) ) ->
	        Head =.. [Name|Args]
	;
	        init(Args,ArgsWOSusp),	% XXX not entirely correct!
	        Head =.. [Name|ArgsWOSusp]
	).

	% return predicate name Result
	% for Fct/Aty constraint symbol and predicate identifier List
buildName(Fct,Aty,List,Result) :-
   ( (chr_pp_flag(debugable,on) ; (once((is_stored(Fct/Aty), ( has_active_occurrence(Fct/Aty) ; chr_pp_flag(late_allocation,off)),
   ( may_trigger(Fct/Aty) ; get_allocation_occurrence(Fct/Aty,AO), get_max_occurrence(Fct/Aty,MO),
   MO >= AO ) ; List \= [0])) ) ) ->
	atom_concat(Fct, '___' ,FctSlash),
	atomic_concat(FctSlash,Aty,FctSlashAty),
	buildName_(List,FctSlashAty,Result)
   ;
	Result = Fct
   ).

buildName_([],Name,Name).
buildName_([N|Ns],Name,Result) :-
  buildName_(Ns,Name,Name1),
  atom_concat(Name1,'__',NameDash),    % '_' is a char :-(
  atomic_concat(NameDash,N,Result).

vars_susp(A,Vars,Susp,VarsSusp) :-
   length(Vars,A),
   append(Vars,[Susp],VarsSusp).

or_pattern(Pos,Pat) :-
	Pow is Pos - 1,
	Pat is 1 << Pow.      % was 2 ** X

and_pattern(Pos,Pat) :-
	X is Pos - 1,
	Y is 1 << X,          % was 2 ** X
	Pat is (-1)*(Y + 1).

make_name(Prefix,F/A,Name) :-
	atom_concat_list([Prefix,F,'___',A],Name).

%===============================================================================
% Attribute for attributed variables

make_attr(N,Mask,SuspsList,Attr) :-
	length(SuspsList,N),
	Attr =.. [v,Mask|SuspsList].

get_all_suspensions2(N,Attr,SuspensionsList) :-
	chr_pp_flag(dynattr,off), !,
	make_attr(N,_,SuspensionsList,Attr).

% NEW
get_all_suspensions2(N,Attr,Goal,SuspensionsList) :-
	% writeln(get_all_suspensions2),
	length(SuspensionsList,N),
	Goal = 'chr all_suspensions'(SuspensionsList,1,Attr).


% NEW
normalize_attr(Attr,NormalGoal,NormalAttr) :-
	% writeln(normalize_attr),
	NormalGoal = 'chr normalize_attr'(Attr,NormalAttr).

get_suspensions(N,Position,TAttr,(TAttr = Attr),Suspensions) :-
	chr_pp_flag(dynattr,off),
	!, % chr_pp_flag(experiment,off), !,
	make_attr(N,_,SuspsList,Attr),
	nth1(Position,SuspsList,Suspensions).

% get_suspensions(N,Position,TAttr,Goal,Suspensions) :-
%	chr_pp_flag(dynattr,off),
%	chr_pp_flag(experiment,on), !,
%	Position1 is Position + 1,
%	Goal = arg(Position1,TAttr,Suspensions).

% NEW
get_suspensions(N,Position,TAttr,Goal,Suspensions) :-
	% writeln(get_suspensions),
	Goal =
	( memberchk(Position-Suspensions,TAttr) ->
			true
	;
		Suspensions = []
	).

%-------------------------------------------------------------------------------
% +N: number of constraint symbols
% +Suspension: source-level variable, for suspension
% +Position: constraint symbol number
% -Attr: source-level term, for new attribute
singleton_attr(N,Suspension,Position,Attr) :-
	chr_pp_flag(dynattr,off), !,
	or_pattern(Position,Pattern),
	make_attr(N,Pattern,SuspsList,Attr),
	nth1(Position,SuspsList,[Suspension],RestSuspsList),
	set_elems(RestSuspsList,[]).

% NEW
singleton_attr(N,Suspension,Position,Attr) :-
	% writeln(singleton_attr),
	Attr = [Position-[Suspension]].

%-------------------------------------------------------------------------------
% +N: number of constraint symbols
% +Suspension: source-level variable, for suspension
% +Position: constraint symbol number
% +TAttr: source-level variable, for old attribute
% -Goal: goal for creating new attribute
% -NTAttr: source-level variable, for new attribute
add_attr(N,Suspension,Position,TAttr,Goal,NTAttr) :-
	chr_pp_flag(dynattr,off), !,
	make_attr(N,Mask,SuspsList,Attr),
	or_pattern(Position,Pattern),
	nth1(Position,SuspsList,Susps),
	substitute_eq(Susps,SuspsList,[Suspension|Susps],SuspsList1),
	make_attr(N,Mask,SuspsList1,NewAttr1),
	substitute_eq(Susps,SuspsList,[Suspension],SuspsList2),
	make_attr(N,NewMask,SuspsList2,NewAttr2),
	Goal = (
		TAttr = Attr,
		( Mask /\ Pattern =:= Pattern ->
			NTAttr = NewAttr1
		;
			NewMask is Mask \/ Pattern,
			NTAttr = NewAttr2
		)
	), !.

% NEW
add_attr(N,Suspension,Position,TAttr,Goal,NTAttr) :-
	% writeln(add_attr),
	Goal =
		( 'chr select'(TAttr,Position-Suspensions,RAttr) ->
			NTAttr = [Position-[Suspension|Suspensions]|RAttr]
		;
			NTAttr = [Position-[Suspension]|TAttr]
		).

rem_attr(N,Var,Suspension,Position,TAttr,Goal) :-
	chr_pp_flag(dynattr,off),
	chr_pp_flag(experiment,off), !,
	or_pattern(Position,Pattern),
	and_pattern(Position,DelPattern),
	make_attr(N,Mask,SuspsList,Attr),
	nth1(Position,SuspsList,Susps),
	substitute_eq(Susps,SuspsList,[],SuspsList1),
	make_attr(N,NewMask,SuspsList1,Attr1),
	substitute_eq(Susps,SuspsList,NewSusps,SuspsList2),
	make_attr(N,Mask,SuspsList2,Attr2),
	get_target_module(Mod),
	Goal = (
		TAttr = Attr,
		( Mask /\ Pattern =:= Pattern ->
			'chr sbag_del_element'(Susps,Suspension,NewSusps),
			( NewSusps == [] ->
				NewMask is Mask /\ DelPattern,
				( NewMask == 0 ->
					del_attr(Var,Mod)
				;
					put_attr(Var,Mod,Attr1)
				)
			;
				put_attr(Var,Mod,Attr2)
			)
		;
			true
		)
	), !.
rem_attr(N,Var,Suspension,Position,TAttr,Goal) :-
	chr_pp_flag(dynattr,off),
	chr_pp_flag(experiment,on), !,
	or_pattern(Position,Pattern),
	and_pattern(Position,DelPattern),
	Position1 is Position + 1,
	get_target_module(Mod),
	Goal = (
		arg(1,TAttr,Mask),
		( Mask /\ Pattern =:= Pattern ->
			arg(Position1,TAttr,Susps),
			'chr sbag_del_element'(Susps,Suspension,NewSusps),
			( NewSusps == [] ->
				NewMask is Mask /\ DelPattern,
				( NewMask == 0 ->
					del_attr(Var,Mod)
				;
					setarg(1,TAttr,NewMask),
					setarg(Position1,TAttr,NewSusps)
				)
			;
				setarg(Position1,TAttr,NewSusps)
			)
		;
			true
		)
	), !.

% NEW
rem_attr(N,Var,Suspension,Position,TAttr,Goal) :-
	% writeln(rem_attr),
	get_target_module(Mod),
	Goal =
		( 'chr select'(TAttr,Position-Suspensions,RAttr) ->
			'chr sbag_del_element'(Suspensions,Suspension,NSuspensions),
			( NSuspensions == [] ->
				( RAttr == [] ->
					del_attr(Var,Mod)
				;
					put_attr(Var,Mod,RAttr)
				)
			;
				put_attr(Var,Mod,[Position-NSuspensions|RAttr])
			)
		;
			true
		).

%-------------------------------------------------------------------------------
% +N: number of constraint symbols
% +TAttr1: source-level variable, for attribute
% +TAttr2: source-level variable, for other attribute
% -Goal: goal for merging the two attributes
% -Attr: source-level term, for merged attribute
merge_attributes(N,TAttr1,TAttr2,Goal,Attr) :-
	chr_pp_flag(dynattr,off), !,
	make_attr(N,Mask1,SuspsList1,Attr1),
	merge_attributes2(N,Mask1,SuspsList1,TAttr2,Goal2,Attr),
	Goal = (
		TAttr1 = Attr1,
		Goal2
	).

% NEW
merge_attributes(N,TAttr1,TAttr2,Goal,Attr) :-
	% writeln(merge_attributes),
	Goal = (
		sort(TAttr1,Sorted1),
		sort(TAttr2,Sorted2),
		'chr new_merge_attributes'(Sorted1,Sorted2,Attr)
	).


%-------------------------------------------------------------------------------
% +N: number of constraint symbols
% +Mask1: ...
% +SuspsList1: static term, for suspensions list
% +TAttr2: source-level variable, for other attribute
% -Goal: goal for merging the two attributes
% -Attr: source-level term, for merged attribute
merge_attributes2(N,Mask1,SuspsList1,TAttr2,Goal,Attr) :-
	make_attr(N,Mask2,SuspsList2,Attr2),
	bagof(G,X ^ Y ^ SY ^ M ^ (member2(SuspsList1,SuspsList2,X-Y),G = (sort(Y,SY),'chr merge_attributes'(X,SY,M))),Gs),
	list2conj(Gs,SortGoals),
	bagof(MS,A ^ B ^ C ^ member((A,'chr merge_attributes'(B,C,MS)),Gs), SuspsList),
	make_attr(N,Mask,SuspsList,Attr),
	Goal = (
		TAttr2 = Attr2,
		SortGoals,
		Mask is Mask1 \/ Mask2
	).


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Storetype dependent lookup

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	lookup_passive_head(+Head,+PreviousVars,+RenamingVarDict,
%%				 -Goal,-SuspensionList) is det.
%
%	Create a universal lookup goal for given head.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
lookup_passive_head(Head,PreJoin,VarDict,Goal,AllSusps) :-
	functor(Head,F,A),
	get_store_type(F/A,StoreType),
	lookup_passive_head(StoreType,Head,PreJoin,VarDict,[],Goal,AllSusps).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	lookup_passive_head(+Head,+PreviousVars,+RenamingVarDict,+GroundVars,
%%				 -Goal,-SuspensionList) is det.
%
%	Create a universal lookup goal for given head.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
lookup_passive_head(Head,PreJoin,VarDict,GroundVars,Goal,AllSusps) :-
	functor(Head,F,A),
	get_store_type(F/A,StoreType),
	lookup_passive_head(StoreType,Head,PreJoin,VarDict,GroundVars,Goal,AllSusps).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	lookup_passive_head(+StoreType,+Head,+PreviousVars,+RenamingVarDict,
%%				 +GroundVars,-Goal,-SuspensionList) is det.
%
%	Create a universal lookup goal for given head.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
lookup_passive_head(default,Head,PreJoin,VarDict,_,Goal,AllSusps) :-
	functor(Head,F,A),
	passive_head_via(Head,PreJoin,VarDict,Goal,AllSusps),
	update_store_type(F/A,default).
lookup_passive_head(multi_inthash(Indexes),Head,_PreJoin,VarDict,GroundVars,Goal,AllSusps) :-
	hash_lookup_passive_head(inthash,Indexes,Head,VarDict,GroundVars,Goal,AllSusps,_).
lookup_passive_head(multi_hash(Indexes),Head,_PreJoin,VarDict,GroundVars,Goal,AllSusps) :-
	hash_lookup_passive_head(hash,Indexes,Head,VarDict,GroundVars,Goal,AllSusps,_).
lookup_passive_head(global_ground,Head,_PreJoin,_VarDict,_,Goal,AllSusps) :-
	functor(Head,F,A),
	global_ground_store_name(F/A,StoreName),
	make_get_store_goal(StoreName,AllSusps,Goal), % Goal = nb_getval(StoreName,AllSusps),
	update_store_type(F/A,global_ground).
lookup_passive_head(var_assoc_store(VarIndex,KeyIndex),Head,_PreJoin,VarDict,_,Goal,AllSusps) :-
	arg(VarIndex,Head,OVar),
	arg(KeyIndex,Head,OKey),
	translate([OVar,OKey],VarDict,[Var,Key]),
	get_target_module(Module),
	Goal = (
		get_attr(Var,Module,AssocStore),
		lookup_assoc_store(AssocStore,Key,AllSusps)
	).
lookup_passive_head(global_singleton,Head,_PreJoin,_VarDict,_,Goal,AllSusps) :-
	functor(Head,F,A),
	global_singleton_store_name(F/A,StoreName),
	make_get_store_goal(StoreName,Susp,GetStoreGoal),
	Goal = (GetStoreGoal,Susp \== [],AllSusps = [Susp]),
	update_store_type(F/A,global_singleton).
lookup_passive_head(multi_store(StoreTypes),Head,PreJoin,VarDict,GroundVars,Goal,AllSusps) :-
	once((
		member(ST,StoreTypes),
		lookup_passive_head(ST,Head,PreJoin,VarDict,GroundVars,Goal,AllSusps)
	)).
lookup_passive_head(identifier_store(Index),Head,PreJoin,VarDict,GroundVars,Goal,AllSusps) :-
	functor(Head,F,A),
	arg(Index,Head,Var),
	translate([Var],VarDict,[KeyVar]),
	delay_phase_end(validate_store_type_assumptions,
		identifier_lookup(F/A,Index,AllSusps,KeyVar,Goal)
	),
	update_store_type(F/A,identifier_store(Index)),
	get_identifier_index(F/A,Index,_).
lookup_passive_head(type_indexed_identifier_store(Index,IndexType),Head,PreJoin,VarDict,GroundVars,Goal,AllSusps) :-
	functor(Head,F,A),
	arg(Index,Head,Var),
	( var(Var) ->
		translate([Var],VarDict,[KeyVar]),
		Goal = StructGoal
	; ground(Var), Var = '$chr_identifier_match'(ActualVar,_) ->
		lookup_only_identifier_atom(IndexType,ActualVar,KeyVar,LookupGoal),
		Goal = (LookupGoal,StructGoal)
	),
	delay_phase_end(validate_store_type_assumptions,
		type_indexed_identifier_lookup(F/A,Index,IndexType,AllSusps,KeyVar,StructGoal)
	),
	update_store_type(F/A,type_indexed_identifier_store(Index,IndexType)),
	get_type_indexed_identifier_index(IndexType,F/A,Index,_).

identifier_lookup(C,Index,AllSusps,KeyVar,Goal) :-
	get_identifier_size(ISize),
	functor(Struct,struct,ISize),
	get_identifier_index(C,Index,IIndex),
	arg(IIndex,Struct,AllSusps),
	Goal = (KeyVar = Struct).

type_indexed_identifier_lookup(C,Index,IndexType,AllSusps,KeyVar,Goal) :-
	type_indexed_identifier_structure(IndexType,Struct),
	get_type_indexed_identifier_index(IndexType,C,Index,IIndex),
	arg(IIndex,Struct,AllSusps),
	Goal = (KeyVar = Struct).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	hash_lookup_passive_head(+StoreType,+Indexes,+Head,+RenamingVarDict,
%%				 +GroundVars,-Goal,-SuspensionList,-Index) is det.
%
%	Create a universal hash lookup goal for given head.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
hash_lookup_passive_head(HashType,Indexes,Head,VarDict,GroundVars,Goal,AllSusps,Index) :-
	pick_hash_index(Indexes,Head,VarDict,Index,KeyArgs,KeyArgCopies),
	( KeyArgCopies = [KeyCopy] ->
		true
	;
		KeyCopy =.. [k|KeyArgCopies]
	),
	functor(Head,F,A),
	multi_hash_lookup_goal(F/A,HashType,Index,KeyCopy,AllSusps,LookupGoal),

	check_ground(GroundVars,KeyArgs,OriginalGroundCheck),
	my_term_copy(OriginalGroundCheck,VarDict,GroundCheck),

	Goal = (GroundCheck,LookupGoal),

	( HashType == inthash ->
		update_store_type(F/A,multi_inthash([Index]))
	;
		update_store_type(F/A,multi_hash([Index]))
	).

pick_hash_index(Indexes,Head,VarDict,Index,KeyArgs,KeyArgCopies) :-
	member(Index,Indexes),
	args(Index,Head,KeyArgs),
	key_in_scope(KeyArgs,VarDict,KeyArgCopies),
	!.

% check whether we can copy the given terms
% with the given dictionary, and, if so, do so
key_in_scope([],VarDict,[]).
key_in_scope([Arg|Args],VarDict,[ArgCopy|ArgCopies]) :-
	term_variables(Arg,Vars),
	translate(Vars,VarDict,VarCopies),
	copy_term(Arg/Vars,ArgCopy/VarCopies),
	key_in_scope(Args,VarDict,ArgCopies).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	existential_lookup(+StoreType,+Head,+PrevVariablesHead,+RenamingVarDict,
%%				+GroundVariables,-SuspensionTerm,-Goal,-SuspVar,
%%				+VarArgDict,-NewVarArgDict) is det.
%
%	Create existential lookup goal for given head.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
existential_lookup(var_assoc_store(VarIndex,KeyIndex),Head,PreJoin,VarDict,GroundVars,SuspTerm,Goal,Susp,Pairs,Pairs) :- !,
	lookup_passive_head(var_assoc_store(VarIndex,KeyIndex),Head,PreJoin,VarDict,GroundVars,UniversalGoal,AllSusps),
	sbag_member_call(Susp,AllSusps,Sbag),
	functor(Head,F,A),
	delay_phase_end(validate_store_type_assumptions,
		( static_suspension_term(F/A,SuspTerm),
		  get_static_suspension_field(F/A,SuspTerm,state,active,GetState)
		)
	),
	Goal = (
		UniversalGoal,
		Sbag,
		Susp = SuspTerm,
		GetState
	).
existential_lookup(global_singleton,Head,_PreJoin,_VarDict,_,SuspTerm,Goal,Susp,Pairs,Pairs) :- !,
	functor(Head,F,A),
	global_singleton_store_name(F/A,StoreName),
	make_get_store_goal(StoreName,Susp,GetStoreGoal),
	Goal =	(
			GetStoreGoal, % nb_getval(StoreName,Susp),
			Susp \== [],
			Susp = SuspTerm
		),
	update_store_type(F/A,global_singleton).
existential_lookup(multi_store(StoreTypes),Head,PreJoin,VarDict,GroundVars,SuspTerm,Goal,Susp,Pairs,NPairs) :- !,
	once((
		member(ST,StoreTypes),
		existential_lookup(ST,Head,PreJoin,VarDict,GroundVars,SuspTerm,Goal,Susp,Pairs,NPairs)
	)).
existential_lookup(multi_inthash(Indexes),Head,_,VarDict,GroundVars,SuspTerm,Goal,Susp,Pairs,NPairs) :- !,
	existential_hash_lookup(inthash,Indexes,Head,VarDict,GroundVars,SuspTerm,Goal,Susp,Pairs,NPairs).
existential_lookup(multi_hash(Indexes),Head,_,VarDict,GroundVars,SuspTerm,Goal,Susp,Pairs,NPairs) :- !,
	existential_hash_lookup(hash,Indexes,Head,VarDict,GroundVars,SuspTerm,Goal,Susp,Pairs,NPairs).
existential_lookup(identifier_store(Index),Head,PreJoin,VarDict,GroundVars,SuspTerm,Goal,Susp,Pairs,NPairs) :- !,
	lookup_passive_head(identifier_store(Index),Head,PreJoin,VarDict,GroundVars,LookupGoal,AllSusps),
	hash_index_filter(Pairs,[Index],NPairs),

	functor(Head,F,A),
	( check_fd_lookup_condition(F,A,Head,KeyArgs) ->
		Sbag = (AllSusps = [Susp])
	;
		sbag_member_call(Susp,AllSusps,Sbag)
	),
	delay_phase_end(validate_store_type_assumptions,
		( static_suspension_term(F/A,SuspTerm),
		  get_static_suspension_field(F/A,SuspTerm,state,active,GetState)
		)
	),
	Goal =	(
			LookupGoal,
			Sbag,
			Susp = SuspTerm,		% not inlined
			GetState
	).
existential_lookup(type_indexed_identifier_store(Index,IndexType),Head,PreJoin,VarDict,GroundVars,SuspTerm,Goal,Susp,Pairs,NPairs) :- !,
	lookup_passive_head(type_indexed_identifier_store(Index,IndexType),Head,PreJoin,VarDict,GroundVars,LookupGoal,AllSusps),
	hash_index_filter(Pairs,[Index],NPairs),

	functor(Head,F,A),
	( check_fd_lookup_condition(F,A,Head,KeyArgs) ->
		Sbag = (AllSusps = [Susp])
	;
		sbag_member_call(Susp,AllSusps,Sbag)
	),
	delay_phase_end(validate_store_type_assumptions,
		( static_suspension_term(F/A,SuspTerm),
		  get_static_suspension_field(F/A,SuspTerm,state,active,GetState)
		)
	),
	Goal =	(
			LookupGoal,
			Sbag,
			Susp = SuspTerm,		% not inlined
			GetState
	).
existential_lookup(StoreType,Head,PreJoin,VarDict,GroundVars,SuspTerm,Goal,Susp,Pairs,Pairs) :-
	lookup_passive_head(StoreType,Head,PreJoin,VarDict,GroundVars,UGoal,Susps),
	sbag_member_call(Susp,Susps,Sbag),
	functor(Head,F,A),
	delay_phase_end(validate_store_type_assumptions,
		( static_suspension_term(F/A,SuspTerm),
		  get_static_suspension_field(F/A,SuspTerm,state,active,GetState)
		)
	),
	Goal =	(
			UGoal,
			Sbag,
			Susp = SuspTerm,		% not inlined
			GetState
		).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	existential_hash_lookup(+StoreType,+Indexes,+Head,+RenamingVarDict,
%%				+GroundVariables,-SuspensionTerm,-Goal,-SuspVar,
%%				+VarArgDict,-NewVarArgDict) is det.
%
%	Create existential hash lookup goal for given head.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
existential_hash_lookup(HashType,Indexes,Head,VarDict,GroundVars,SuspTerm,Goal,Susp,Pairs,NPairs) :-
	hash_lookup_passive_head(HashType,Indexes,Head,VarDict,GroundVars,LookupGoal,AllSusps,Index),

	hash_index_filter(Pairs,Index,NPairs),

	functor(Head,F,A),
	( check_fd_lookup_condition(F,A,Head,KeyArgs) ->
		Sbag = (AllSusps = [Susp])
	;
		sbag_member_call(Susp,AllSusps,Sbag)
	),
	delay_phase_end(validate_store_type_assumptions,
		( static_suspension_term(F/A,SuspTerm),
		  get_static_suspension_field(F/A,SuspTerm,state,active,GetState)
		)
	),
	Goal =	(
			LookupGoal,
			Sbag,
			Susp = SuspTerm,		% not inlined
			GetState
	).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
%%	hash_index_filter(+Pairs,+Index,-NPairs) is det.
%
%	Filter out pairs already covered by given hash index.
%	makes them 'silent'
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%
hash_index_filter(Pairs,Index,NPairs) :-
	hash_index_filter(Pairs,Index,1,NPairs).

hash_index_filter([],_,_,[]).
hash_index_filter([P|Ps],Index,N,NPairs) :-
	( Index = [I|Is] ->
		NN is N + 1,
		( I > N ->
			NPairs = [P|NPs],
			hash_index_filter(Ps,[I|Is],NN,NPs)
		; I == N ->
			NPairs = [silent(P)|NPs],
			hash_index_filter(Ps,Is,NN,NPs)
		)
	;
		NPairs = [P|Ps]
	).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%------------------------------------------------------------------------------%
%%	assume_constraint_stores(+ConstraintSymbols) is det.
%
%	Compute all constraint store types that are possible for the given
%	=ConstraintSymbols=.
%------------------------------------------------------------------------------%
assume_constraint_stores([]).
assume_constraint_stores([C|Cs]) :-
	( chr_pp_flag(debugable,off),
	  ( only_ground_indexed_arguments(C) ; chr_pp_flag(mixed_stores,on) ),
	  is_stored(C),
	  get_store_type(C,default) ->
		get_indexed_arguments(C,AllIndexedArgs),
		get_constraint_mode(C,Modes),
		aggregate_all(bag(Index)-count,
					(member(Index,AllIndexedArgs),nth1(Index,Modes,+)),
			      IndexedArgs-NbIndexedArgs),
		% Construct Index Combinations
		( NbIndexedArgs > 10 ->
			findall([Index],member(Index,IndexedArgs),Indexes)
		;
			findall(Index,(sublist(Index,IndexedArgs), Index \== []),UnsortedIndexes),
			predsort(longer_list,UnsortedIndexes,Indexes)
		),
		% EXPERIMENTAL HEURISTIC
		% findall(Index, (
		%			member(Arg1,IndexedArgs),
		%			member(Arg2,IndexedArgs),
		%			Arg1 =< Arg2,
		%			sort([Arg1,Arg2], Index)
		%		), UnsortedIndexes),
		% predsort(longer_list,UnsortedIndexes,Indexes),
		% Choose Index Type
		( get_functional_dependency(C,1,Pattern,Key),
		  all_distinct_var_args(Pattern), Key == [] ->
			assumed_store_type(C,global_singleton)
		; ( only_ground_indexed_arguments(C) ; NbIndexedArgs > 0 ) ->
			get_constraint_type_det(C,ArgTypes),
			partition_indexes(Indexes,ArgTypes,HashIndexes,IntHashIndexes,IdentifierIndexes,CompoundIdentifierIndexes),

			( IntHashIndexes = [] ->
				Stores = Stores1
			;
				Stores = [multi_inthash(IntHashIndexes)|Stores1]
			),
			( HashIndexes = [] ->
				Stores1 = Stores2
			;
				Stores1 = [multi_hash(HashIndexes)|Stores2]
			),
			( IdentifierIndexes = [] ->
				Stores2 = Stores3
			;
				maplist(wrap_in_functor(identifier_store),IdentifierIndexes,WrappedIdentifierIndexes),
				append(WrappedIdentifierIndexes,Stores3,Stores2)
			),
			append(CompoundIdentifierIndexes,Stores4,Stores3),
			(   only_ground_indexed_arguments(C)
			->  Stores4 = [global_ground]
			;   Stores4 = [default]
			),
			assumed_store_type(C,multi_store(Stores))
		;	true
		)
	;
		true
	),
	assume_constraint_stores(Cs).

%------------------------------------------------------------------------------%
%%	partition_indexes(+Indexes,+Types,
%%		-HashIndexes,-IntHashIndexes,-IdentifierIndexes) is det.
%------------------------------------------------------------------------------%
partition_indexes([],_,[],[],[],[]).
partition_indexes([Index|Indexes],Types,HashIndexes,IntHashIndexes,IdentifierIndexes,CompoundIdentifierIndexes) :-
	( Index = [I],
	  nth1(I,Types,Type),
	  unalias_type(Type,UnAliasedType),
	  UnAliasedType == chr_identifier ->
		IdentifierIndexes = [I|RIdentifierIndexes],
		IntHashIndexes = RIntHashIndexes,
		HashIndexes = RHashIndexes,
		CompoundIdentifierIndexes = RCompoundIdentifierIndexes
	; Index = [I],
	  nth1(I,Types,Type),
	  unalias_type(Type,UnAliasedType),
	  nonvar(UnAliasedType),
	  UnAliasedType = chr_identifier(IndexType) ->
		CompoundIdentifierIndexes = [type_indexed_identifier_store(I,IndexType)|RCompoundIdentifierIndexes],
		IdentifierIndexes = RIdentifierIndexes,
		IntHashIndexes = RIntHashIndexes,
		HashIndexes = RHashIndexes
	; Index = [I],
	  nth1(I,Types,Type),
	  unalias_type(Type,UnAliasedType),
	  UnAliasedType == dense_int ->
		IntHashIndexes = [Index|RIntHashIndexes],
		HashIndexes = RHashIndexes,
		IdentifierIndexes = RIdentifierIndexes,
		CompoundIdentifierIndexes = RCompoundIdentifierIndexes
	; member(I,Index),
	  nth1(I,Types,Type),
	  unalias_type(Type,UnAliasedType),
	  nonvar(UnAliasedType),
	  UnAliasedType = chr_identifier(_) ->
		% don't use chr_identifiers in hash indexes
		IntHashIndexes = RIntHashIndexes,
		HashIndexes = RHashIndexes,
		IdentifierIndexes = RIdentifierIndexes,
		CompoundIdentifierIndexes = RCompoundIdentifierIndexes
	;
		IntHashIndexes = RIntHashIndexes,
		HashIndexes = [Index|RHashIndexes],
		IdentifierIndexes = RIdentifierIndexes,
		CompoundIdentifierIndexes = RCompoundIdentifierIndexes
	),
	partition_indexes(Indexes,Types,RHashIndexes,RIntHashIndexes,RIdentifierIndexes,RCompoundIdentifierIndexes).

longer_list(R,L1,L2) :-
	length(L1,N1),
	length(L2,N2),
	compare(Rt,N2,N1),
	( Rt == (=) ->
		compare(R,L1,L2)
	;
		R = Rt
	).

all_distinct_var_args(Term) :-
	copy_term_nat(Term,TermCopy),
	functor(Term,F,A),
	functor(Pattern,F,A),
	Pattern =@= TermCopy.

get_indexed_arguments(C,IndexedArgs) :-
	C = F/A,
	get_indexed_arguments(1,A,C,IndexedArgs).

get_indexed_arguments(I,N,C,L) :-
	( I > N ->
		L = []
	;	( is_indexed_argument(C,I) ->
			L = [I|T]
		;
			L = T
		),
		J is I + 1,
		get_indexed_arguments(J,N,C,T)
	).

validate_store_type_assumptions([]).
validate_store_type_assumptions([C|Cs]) :-
	validate_store_type_assumption(C),
	validate_store_type_assumptions(Cs).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% new code generation
universal_search_iterator_end([CurrentHead|PrevHeads],NextHeads,Rule,F/A,O,Id,L,T) :-
	Rule = rule(H1,_,Guard,Body),
	gen_var_susp_list_for_b(PrevHeads,[CurrentHead,NextHeads,Guard,Body],_,VarsAndSuspsList,FirstVarsSusp,_,PrevIterators),
	universal_search_iterator_failure_vars(PrevHeads,Id,VarsAndSuspsList,FirstVarsSusp,PrevIterators,PrevVarsAndSusps,PrevId0),
	flatten(VarsAndSuspsList,VarsAndSusps),
	Vars = [ [] | VarsAndSusps],
	build_head(F,A,[O|Id],Vars,Head),
	( PrevId0 = [_] ->
		get_success_continuation_code_id(F/A,O,PredictedPrevId),
		% format('~w == ~w ?\n',[PrevId0,PredictedPrevId]),
		PrevId = [PredictedPrevId] % PrevId = PrevId0
	;
		PrevId = [O|PrevId0]
	),
	build_head(F,A,PrevId,PrevVarsAndSusps,PredecessorCall),
	Clause = ( Head :- PredecessorCall),
	add_dummy_location(Clause,LocatedClause),
	L = [LocatedClause | T].
%	( H1 == [],
%	  functor(CurrentHead,CF,CA),
%	  check_fd_lookup_condition(CF,CA,CurrentHead,PrevHeads) ->
%		L = T
%	;
%		gen_var_susp_list_for_b(PrevHeads,[CurrentHead,NextHeads,Guard,Body],_,VarsAndSuspsList,FirstVarsSusp,_,PrevIterators),
%		universal_search_iterator_failure_vars(PrevHeads,Id,VarsAndSuspsList,FirstVarsSusp,PrevIterators,PrevVarsAndSusps,PrevId),
%		flatten(VarsAndSuspsList,VarsAndSusps),
%		Vars = [ [] | VarsAndSusps],
%		build_head(F,A,Id,Vars,Head),
%		build_head(F,A,PrevId,PrevVarsAndSusps,PredecessorCall),
%		Clause = ( Head :- PredecessorCall),
%		L = [Clause | T]
%	).

	% skips back intelligently over global_singleton lookups
universal_search_iterator_failure_vars(PrevHeads,Id,VarsAndSuspsList,BaseCallArgs,PrevIterators,PrevVarsAndSusps,PrevId) :-
	( Id = [0|_] ->
		% TOM: add partial success continuation optimization here!
		next_id(Id,PrevId),
		PrevVarsAndSusps = BaseCallArgs
	;
		VarsAndSuspsList = [_|AllButFirstList],
		dec_id(Id,PrevId1),
		( PrevHeads  = [PrevHead|PrevHeads1],
		  functor(PrevHead,F,A),
		  check_fd_lookup_condition(F,A,PrevHead,PrevHeads1) ->
			PrevIterators = [_|PrevIterators1],
			universal_search_iterator_failure_vars(PrevHeads1,PrevId1,AllButFirstList,BaseCallArgs,PrevIterators1,PrevVarsAndSusps,PrevId)
		;
			PrevId = PrevId1,
			flatten(AllButFirstList,AllButFirst),
			PrevIterators = [PrevIterator|_],
			PrevVarsAndSusps = [PrevIterator|AllButFirst]
		)
	).

universal_search_iterator([NextHead|RestHeads],[CurrentHead|PreHeads],Rule,F/A,O,Id,L,T) :-
	Rule = rule(_,_,Guard,Body),
	gen_var_susp_list_for_b(PreHeads,[CurrentHead,NextHead,RestHeads,Guard,Body],VarDict,PreVarsAndSuspsList,FirstVarsSusp,AllSusps,PrevIterators),
	init(AllSusps,PreSusps),
	flatten(PreVarsAndSuspsList,PreVarsAndSusps),
	gen_var(OtherSusps),
	functor(CurrentHead,OtherF,OtherA),
	gen_vars(OtherA,OtherVars),
	head_info(CurrentHead,OtherA,OtherVars,OtherSusp,_VarsSusp,HeadPairs),
	get_constraint_mode(OtherF/OtherA,Mode),
	head_arg_matches(HeadPairs,Mode,VarDict,FirstMatching,VarDict1),

	delay_phase_end(validate_store_type_assumptions,
		( static_suspension_term(OtherF/OtherA,OtherSuspension),
		  get_static_suspension_field(OtherF/OtherA,OtherSuspension,state,active,GetState),
		  get_static_suspension_term_field(arguments,OtherF/OtherA,OtherSuspension,OtherVars)
		)
	),

	different_from_other_susps(CurrentHead,OtherSusp,PreHeads,PreSusps,DiffSuspGoals),
	% create_get_mutable_ref(active,State,GetMutable),
	CurrentSuspTest = (
	   OtherSusp = OtherSuspension,
	   GetState,
	   DiffSuspGoals,
	   FirstMatching
	),
	add_heads_ground_variables([CurrentHead|PreHeads],[],GroundVars),
        lookup_passive_head(NextHead,[CurrentHead|PreHeads],VarDict1,GroundVars,NextSuspGoal,NextSusps),
	inc_id(Id,NestedId),
	ClauseVars = [[OtherSusp|OtherSusps]|PreVarsAndSusps],
	build_head(F,A,[O|Id],ClauseVars,ClauseHead),
	passive_delegate_variables(CurrentHead,PreHeads,[NextHead,RestHeads,Guard,Body],VarDict1,CurrentHeadVars),
	append([NextSusps|CurrentHeadVars],[OtherSusp,OtherSusps|PreVarsAndSusps],NestedVars),
	build_head(F,A,[O|NestedId],NestedVars,NestedHead),

	( check_fd_lookup_condition(OtherF,OtherA,CurrentHead,PreHeads) ->	% iterator (OtherSusps) is empty at runtime
		universal_search_iterator_failure_vars(PreHeads,Id,PreVarsAndSuspsList,FirstVarsSusp,PrevIterators,PreVarsAndSusps1,PrevId0),
		RecursiveVars = PreVarsAndSusps1
	;
		RecursiveVars = [OtherSusps|PreVarsAndSusps],
		PrevId0 = Id
	),
	( PrevId0 = [_] ->
		PrevId = PrevId0
	;
		PrevId = [O|PrevId0]
	),
	build_head(F,A,PrevId,RecursiveVars,RecursiveHead),

	Clause = (
	   ClauseHead :-
	   (   CurrentSuspTest,
	       NextSuspGoal
	       ->
	       NestedHead
	   ;   RecursiveHead
	   )
	),
	add_dummy_location(Clause,LocatedClause),
	L = [LocatedClause|T].

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Observation Analysis
%
% CLASSIFICATION
%   Enabled
%
% Analysis based on Abstract Interpretation paper.
%
% TODO:
%   stronger analysis domain [research]

:- chr_constraint
	initial_call_pattern/1,
	call_pattern/1,
	call_pattern_worker/1,
	final_answer_pattern/2,
	abstract_constraints/1,
	depends_on/2,
	depends_on_ap/4,
	depends_on_goal/2,
	ai_observed_internal/2,
	% ai_observed/2,
	ai_not_observed_internal/2,
	ai_not_observed/2,
	ai_is_observed/2,
	depends_on_as/3,
	ai_observation_gather_results/0.

:- chr_type abstract_domain	--->	odom(program_point,list(constraint)).
:- chr_type program_point	==	any.

:- chr_option(mode,initial_call_pattern(+)).
:- chr_option(type_declaration,call_pattern(abstract_domain)).

:- chr_option(mode,call_pattern(+)).
:- chr_option(type_declaration,call_pattern(abstract_domain)).

:- chr_option(mode,call_pattern_worker(+)).
:- chr_option(type_declaration,call_pattern_worker(abstract_domain)).

:- chr_option(mode,final_answer_pattern(+,+)).
:- chr_option(type_declaration,final_answer_pattern(abstract_domain,abstract_domain)).

:- chr_option(mode,abstract_constraints(+)).
:- chr_option(type_declaration,abstract_constraints(list)).

:- chr_option(mode,depends_on(+,+)).
:- chr_option(type_declaration,depends_on(abstract_domain,abstract_domain)).

:- chr_option(mode,depends_on_as(+,+,+)).
:- chr_option(mode,depends_on_ap(+,+,+,+)).
:- chr_option(mode,depends_on_goal(+,+)).
:- chr_option(mode,ai_is_observed(+,+)).
:- chr_option(mode,ai_not_observed(+,+)).
% :- chr_option(mode,ai_observed(+,+)).
:- chr_option(mode,ai_not_observed_internal(+,+)).
:- chr_option(mode,ai_observed_internal(+,+)).


abstract_constraints_fd @
	abstract_constraints(_) \ abstract_constraints(_) <=> true.

ai_observed_internal(C,O) \ ai_not_observed_internal(C,O) <=> true.
ai_not_observed_internal(C,O) \ ai_not_observed_internal(C,O) <=> true.
ai_observed_internal(C,O) \ ai_observed_internal(C,O) <=> true.

ai_not_observed(C,O) \ ai_is_observed(C,O) <=> fail.
ai_is_observed(_,_) <=> true.

ai_observation_gather_results \ ai_observed_internal(C,O) <=> true. % ai_observed(C,O).
ai_observation_gather_results \ ai_not_observed_internal(C,O) <=> ai_not_observed(C,O).
ai_observation_gather_results <=> true.

%------------------------------------------------------------------------------%
% Main Analysis Entry
%------------------------------------------------------------------------------%
ai_observation_analysis(ACs) :-
    ( chr_pp_flag(ai_observation_analysis,on),
	get_target_module(Module), '$chr_compiled_with_version'(3) -> % , Module \== guard_entailment ->
	list_to_ord_set(ACs,ACSet),
	abstract_constraints(ACSet),
	ai_observation_schedule_initial_calls(ACSet,ACSet),
	ai_observation_gather_results
    ;
	true
    ).

ai_observation_schedule_initial_calls([],_).
ai_observation_schedule_initial_calls([AC|RACs],ACs) :-
	ai_observation_schedule_initial_call(AC,ACs),
	ai_observation_schedule_initial_calls(RACs,ACs).

ai_observation_schedule_initial_call(AC,ACs) :-
	ai_observation_top(AC,CallPattern),
	% ai_observation_bot(AC,ACs,CallPattern),
	initial_call_pattern(CallPattern).

ai_observation_schedule_new_calls([],AP).
ai_observation_schedule_new_calls([AC|ACs],AP) :-
	AP = odom(_,Set),
	initial_call_pattern(odom(AC,Set)),
	ai_observation_schedule_new_calls(ACs,AP).

final_answer_pattern(CP,AP1) \ final_answer_pattern(CP,AP2)
	<=>
		ai_observation_leq(AP2,AP1)
	|
		true.

initial_call_pattern(CP) \ initial_call_pattern(CP) <=> true.

initial_call_pattern(CP) ==> call_pattern(CP).

initial_call_pattern(CP), final_answer_pattern(CP,AP), abstract_constraints(ACs) # ID3
	==>
		ai_observation_schedule_new_calls(ACs,AP)
	pragma
		passive(ID3).

call_pattern(CP) \ call_pattern(CP) <=> true.

depends_on(CP1,CP2), final_answer_pattern(CP2,AP) ==>
	final_answer_pattern(CP1,AP).

 %call_pattern(CP) ==> writeln(call_pattern(CP)).

call_pattern(CP) ==> call_pattern_worker(CP).

%------------------------------------------------------------------------------%
% Abstract Goal
%------------------------------------------------------------------------------%

	% AbstractGoala
%call_pattern(odom([],Set)) ==>
%	final_answer_pattern(odom([],Set),odom([],Set)).

call_pattern_worker(odom([],Set)) <=>
	% writeln(' - AbstractGoal'(odom([],Set))),
	final_answer_pattern(odom([],Set),odom([],Set)).

	% AbstractGoalb
call_pattern_worker(odom([G|Gs],Set)) <=>
	% writeln(' - AbstractGoal'(odom([G|Gs],Set))),
	CP1 = odom(G,Set),
	depends_on_goal(odom([G|Gs],Set),CP1),
	call_pattern(CP1).

depends_on_goal(CP1,CP2), final_answer_pattern(CP2,AP2) \ depends_on(CP1,_) # ID
	<=> true pragma passive(ID).
depends_on_goal(CP1,CP2), final_answer_pattern(CP2,AP2)
	==>
		CP1 = odom([_|Gs],_),
		AP2 = odom([],Set),
		CCP = odom(Gs,Set),
		call_pattern(CCP),
		depends_on(CP1,CCP).

%------------------------------------------------------------------------------%
% Abstract Disjunction
%------------------------------------------------------------------------------%

call_pattern_worker(odom((AG1;AG2),Set)) <=>
	CP = odom((AG1;AG2),Set),
	InitialAnswerApproximation = odom([],Set),
	final_answer_pattern(CP,InitialAnswerApproximation),
	CP1 = odom(AG1,Set),
	CP2 = odom(AG2,Set),
	call_pattern(CP1),
	call_pattern(CP2),
	depends_on_as(CP,CP1,CP2).

%------------------------------------------------------------------------------%
% Abstract Solve
%------------------------------------------------------------------------------%
call_pattern_worker(odom(builtin,Set)) <=>
	% writeln('  - AbstractSolve'(odom(builtin,Set))),
	ord_empty(EmptySet),
	final_answer_pattern(odom(builtin,Set),odom([],EmptySet)).

%------------------------------------------------------------------------------%
% Abstract Drop
%------------------------------------------------------------------------------%
max_occurrence(C,MO) # ID2 \ call_pattern_worker(odom(occ(C,O),Set))
	<=>
		O > MO
	|
		% writeln('  - AbstractDrop'(odom(occ(C,O),Set))),
		final_answer_pattern(odom(occ(C,O),Set),odom([],Set))
	pragma
		passive(ID2).

%------------------------------------------------------------------------------%
% Abstract Activate
%------------------------------------------------------------------------------%
call_pattern_worker(odom(AC,Set))
	<=>
		AC = _ / _
	|
		% writeln('  - AbstractActivate'(odom(AC,Set))),
		CP = odom(occ(AC,1),Set),
		call_pattern(CP),
		depends_on(odom(AC,Set),CP).

%------------------------------------------------------------------------------%
% Abstract Passive
%------------------------------------------------------------------------------%
occurrence(C,O,RuleNb,ID,_) # ID2 \ call_pattern_worker(odom(occ(C,O),Set))
	<=>
		is_passive(RuleNb,ID)
	|
		% writeln(' - AbstractPassive'(odom(occ(C,O),Set))),
		% DEFAULT
		NO is O + 1,
		DCP = odom(occ(C,NO),Set),
		call_pattern(DCP),
		final_answer_pattern(odom(occ(C,O),Set),odom([],Set)),
		depends_on(odom(occ(C,O),Set),DCP)
	pragma
		passive(ID2).
%------------------------------------------------------------------------------%
% Abstract Simplify
%------------------------------------------------------------------------------%

	% AbstractSimplify
occurrence(C,O,RuleNb,ID,simplification) # ID2 \ call_pattern_worker(odom(occ(C,O),Set))
	<=>
		\+ is_passive(RuleNb,ID)
	|
		% writeln(' - AbstractPassive'(odom(occ(C,O),Set))),
		ai_observation_memo_simplification_rest_heads(C,O,AbstractRestHeads),
		ai_observation_observe_set(Set,AbstractRestHeads,Set2),
		ai_observation_memo_abstract_goal(RuleNb,AG),
		call_pattern(odom(AG,Set2)),
		% DEFAULT
		NO is O + 1,
		DCP = odom(occ(C,NO),Set),
		call_pattern(DCP),
		depends_on_as(odom(occ(C,O),Set),odom(AG,Set2),DCP),
		% DEADLOCK AVOIDANCE
		final_answer_pattern(odom(occ(C,O),Set),odom([],Set))
	pragma
		passive(ID2).

depends_on_as(CP,CPS,CPD),
	final_answer_pattern(CPS,APS),
	final_answer_pattern(CPD,APD) ==>
	ai_observation_lub(APS,APD,AP),
	final_answer_pattern(CP,AP).


:- chr_constraint
	ai_observation_memo_simplification_rest_heads/3,
	ai_observation_memoed_simplification_rest_heads/3.

:- chr_option(mode,ai_observation_memo_simplification_rest_heads(+,+,?)).
:- chr_option(mode,ai_observation_memoed_simplification_rest_heads(+,+,+)).

ai_observation_memoed_simplification_rest_heads(C,O,RH) \ ai_observation_memo_simplification_rest_heads(C,O,QRH)
	<=>
		QRH = RH.
abstract_constraints(ACs) # ID1, occurrence(C,O,RuleNb,ID,_) # ID2, rule(RuleNb,Rule) # ID3 \ ai_observation_memo_simplification_rest_heads(C,O,QRH)
	<=>
		Rule = pragma(rule(H1,H2,_,_),ids(IDs1,_),_,_,_),
		once(select2(ID,_,IDs1,H1,_,RestH1)),
		ai_observation_abstract_constraints(RestH1,ACs,ARestHeads),
		ai_observation_abstract_constraints(H2,ACs,AH2),
		append(ARestHeads,AH2,AbstractHeads),
		sort(AbstractHeads,QRH),
		ai_observation_memoed_simplification_rest_heads(C,O,QRH)
	pragma
		passive(ID1),
		passive(ID2),
		passive(ID3).

ai_observation_memo_simplification_rest_heads(_,_,_) <=> fail.

%------------------------------------------------------------------------------%
% Abstract Propagate
%------------------------------------------------------------------------------%


	% AbstractPropagate
occurrence(C,O,RuleNb,ID,propagation) # ID2 \ call_pattern_worker(odom(occ(C,O),Set))
	<=>
		\+ is_passive(RuleNb,ID)
	|
		% writeln('  - AbstractPropagate'(odom(occ(C,O),Set))),
		% observe partners
		ai_observation_memo_propagation_rest_heads(C,O,AHs),
		ai_observation_observe_set(Set,AHs,Set2),
		ord_add_element(Set2,C,Set3),
		ai_observation_memo_abstract_goal(RuleNb,AG),
		call_pattern(odom(AG,Set3)),
		( ord_memberchk(C,Set2) ->
			Delete = no
		;
			Delete = yes
		),
		% DEFAULT
		NO is O + 1,
		DCP = odom(occ(C,NO),Set),
		call_pattern(DCP),
		depends_on_ap(odom(occ(C,O),Set),odom(AG,Set3),DCP,Delete)
	pragma
		passive(ID2).

:- chr_constraint
	ai_observation_memo_propagation_rest_heads/3,
	ai_observation_memoed_propagation_rest_heads/3.

:- chr_option(mode,ai_observation_memo_propagation_rest_heads(+,+,?)).
:- chr_option(mode,ai_observation_memoed_propagation_rest_heads(+,+,+)).

ai_observation_memoed_propagation_rest_heads(C,O,RH) \ ai_observation_memo_propagation_rest_heads(C,O,QRH)
	<=>
		QRH = RH.
abstract_constraints(ACs) # ID1, occurrence(C,O,RuleNb,ID,_) # ID2, rule(RuleNb,Rule) # ID3 \ ai_observation_memo_propagation_rest_heads(C,O,QRH)
	<=>
		Rule = pragma(rule(H1,H2,_,_),ids(_,IDs2),_,_,_),
		once(select2(ID,_,IDs2,H2,_,RestH2)),
		ai_observation_abstract_constraints(RestH2,ACs,ARestHeads),
		ai_observation_abstract_constraints(H1,ACs,AH1),
		append(ARestHeads,AH1,AbstractHeads),
		sort(AbstractHeads,QRH),
		ai_observation_memoed_propagation_rest_heads(C,O,QRH)
	pragma
		passive(ID1),
		passive(ID2),
		passive(ID3).

ai_observation_memo_propagation_rest_heads(_,_,_) <=> fail.

depends_on_ap(CP,CPP,CPD,Delete), final_answer_pattern(CPD,APD) ==>
	final_answer_pattern(CP,APD).
depends_on_ap(CP,CPP,CPD,Delete), final_answer_pattern(CPP,APP),
	final_answer_pattern(CPD,APD) ==>
	true |
	CP = odom(occ(C,O),_),
	( ai_observation_is_observed(APP,C) ->
		ai_observed_internal(C,O)
	;
		ai_not_observed_internal(C,O)
	),
	( Delete == yes ->
		APP = odom([],Set0),
		ord_del_element(Set0,C,Set),
		NAPP = odom([],Set)
	;
		NAPP = APP
	),
	ai_observation_lub(NAPP,APD,AP),
	final_answer_pattern(CP,AP).

%------------------------------------------------------------------------------%
% Catch All
%------------------------------------------------------------------------------%

call_pattern_worker(CP) <=> chr_error(internal,'AI observation analysis: unexpected abstract state ~w\n',[CP]).

%------------------------------------------------------------------------------%
% Auxiliary Predicates
%------------------------------------------------------------------------------%

ai_observation_lub(odom(AG,S1),odom(AG,S2),odom(AG,S3)) :-
	ord_intersection(S1,S2,S3).

ai_observation_bot(AG,AS,odom(AG,AS)).

ai_observation_top(AG,odom(AG,EmptyS)) :-
	ord_empty(EmptyS).

ai_observation_leq(odom(AG,S1),odom(AG,S2)) :-
	ord_subset(S2,S1).

ai_observation_observe_set(S,ACSet,NS) :-
	ord_subtract(S,ACSet,NS).

ai_observation_abstract_constraint(C,ACs,AC) :-
	functor(C,F,A),
	AC = F/A,
	memberchk(AC,ACs).

ai_observation_abstract_constraints(Cs,ACs,NACs) :-
	findall(NAC,(member(C,Cs),ai_observation_abstract_constraint(C,ACs,NAC)),NACs).

%------------------------------------------------------------------------------%
% Abstraction of Rule Bodies
%------------------------------------------------------------------------------%

:- chr_constraint
	ai_observation_memoed_abstract_goal/2,
	ai_observation_memo_abstract_goal/2.

:- chr_option(mode,ai_observation_memoed_abstract_goal(+,+)).
:- chr_option(mode,ai_observation_memo_abstract_goal(+,?)).

ai_observation_memoed_abstract_goal(RuleNb,AG) # ID1 \ ai_observation_memo_abstract_goal(RuleNb,QAG)
	<=>
		QAG = AG
	pragma
		passive(ID1).

rule(RuleNb,Rule) # ID1, abstract_constraints(ACs) # ID2 \ ai_observation_memo_abstract_goal(RuleNb,QAG)
	<=>
		Rule = pragma(rule(H1,H2,Guard,Body),_,_,_,_),
		ai_observation_abstract_goal_(H1,H2,Guard,Body,ACs,AG),
		QAG = AG,
		ai_observation_memoed_abstract_goal(RuleNb,AG)
	pragma
		passive(ID1),
		passive(ID2).

ai_observation_abstract_goal_(H1,H2,Guard,G,ACs,AG) :-
	% also guard: e.g. b, c(X) ==> Y=X | p(Y).
	term_variables((H1,H2,Guard),HVars),
	append(H1,H2,Heads),
	% variables that are declared to be ground are safe,
	ground_vars(Heads,GroundVars),
	% so we remove them from the list of 'dangerous' head variables
	list_difference_eq(HVars,GroundVars,HV),
	ai_observation_abstract_goal(G,ACs,AG,[],HV),!.
	% writeln(ai_observation_abstract_goal(G,ACs,AG,[],HV)).
	% HV are 'dangerous' variables, all others are fresh and safe

ground_vars([],[]).
ground_vars([H|Hs],GroundVars) :-
	functor(H,F,A),
	get_constraint_mode(F/A,Mode),
	% TOM: fix this code!
	head_info(H,A,_Vars,_Susp,_HeadVars,HeadPairs),
	head_arg_matches(HeadPairs,Mode,[],_FirstMatching,_VarDict1,[],GroundVars1),
	ground_vars(Hs,GroundVars2),
	append(GroundVars1,GroundVars2,GroundVars).

ai_observation_abstract_goal((G1,G2),ACs,List,Tail,HV) :- !,	% conjunction
	ai_observation_abstract_goal(G1,ACs,List,IntermediateList,HV),
	ai_observation_abstract_goal(G2,ACs,IntermediateList,Tail,HV).
ai_observation_abstract_goal((G1;G2),ACs,[(ABranch1;ABranch2)|Tail],Tail,HV) :- !,	% disjunction
	ai_observation_abstract_goal(G1,ACs,ABranch1,[],HV),
	ai_observation_abstract_goal(G2,ACs,ABranch2,[],HV).
ai_observation_abstract_goal((G1->G2),ACs,List,Tail,HV) :- !,	% if-then
	ai_observation_abstract_goal(G1,ACs,List,IntermediateList,HV),
	ai_observation_abstract_goal(G2,ACs,IntermediateList,Tail,HV).
ai_observation_abstract_goal(C,ACs,[AC|Tail],Tail,HV) :-
	ai_observation_abstract_constraint(C,ACs,AC), !.	% CHR constraint
ai_observation_abstract_goal(true,_,Tail,Tail,_) :- !.
ai_observation_abstract_goal(writeln(_),_,Tail,Tail,_) :- !.
% non-CHR constraint is safe if it only binds fresh variables
ai_observation_abstract_goal(G,_,Tail,Tail,HV) :-
	builtin_binds_b(G,Vars),
	intersect_eq(Vars,HV,[]),
	!.
ai_observation_abstract_goal(G,_,[AG|Tail],Tail,_) :-
	AG = builtin. % default case if goal is not recognized/safe

ai_observation_is_observed(odom(_,ACSet),AC) :-
	\+ ord_memberchk(AC,ACSet).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
unconditional_occurrence(C,O) :-
	get_occurrence(C,O,RuleNb,ID),
	get_rule(RuleNb,PRule),
	PRule = pragma(ORule,_,_,_,_),
	copy_term_nat(ORule,Rule),
	Rule = rule(H1,H2,Guard,_),
	guard_entailment:entails_guard([chr_pp_headvariables(H1,H2)],Guard),
	once((
		H1 = [Head], H2 == []
	     ;
		H2 = [Head], H1 == [], \+ may_trigger(C)
	)),
	all_distinct_var_args(Head).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
% Partial wake analysis
%
% In a Var = Var unification do not wake up constraints of both variables,
% but rather only those of one variable.
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

:- chr_constraint partial_wake_analysis/0.
:- chr_constraint no_partial_wake/1.
:- chr_option(mode,no_partial_wake(+)).
:- chr_constraint wakes_partially/1.
:- chr_option(mode,wakes_partially(+)).

partial_wake_analysis, occurrence(FA,O,RuleNb,ID,Type),  rule(RuleNb,Rule), constraint_mode(FA,ArgModes)
	==>
		Rule = pragma(rule(H1,H2,Guard,Body),_,_,_,_),
		( is_passive(RuleNb,ID) ->
			true
		; Type == simplification ->
			select(H,H1,RestH1),
			H =.. [_|Args],
			term_variables(Guard,Vars),
			partial_wake_args(Args,ArgModes,Vars,FA)
		; % Type == propagation  ->
			select(H,H2,RestH2),
			H =.. [_|Args],
			term_variables(Guard,Vars),
			partial_wake_args(Args,ArgModes,Vars,FA)
		).

partial_wake_args([],_,_,_).
partial_wake_args([Arg|Args],[Mode|Modes],Vars,C) :-
	( Mode \== (+) ->
		( nonvar(Arg) ->
			no_partial_wake(C)
		; memberchk_eq(Arg,Vars) ->
			no_partial_wake(C)
		;
			true
		)
	;
		true
	),
	partial_wake_args(Args,Modes,Vars,C).

no_partial_wake(C) \ no_partial_wake(C) <=> true.

no_partial_wake(C) \ wakes_partially(C) <=> fail.

wakes_partially(C) <=> true.


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Generate rules that implement chr_show_store/1 functionality.
%
% CLASSIFICATION
%   Experimental
%   Unused
%
% Generates additional rules:
%
%   $show, C1 # ID ==> writeln(C1) pragma passive(ID).
%   ...
%   $show, Cn # ID ==> writeln(Cn) pragma passive(ID).
%   $show <=> true.

generate_show_constraint(Constraints0,Constraints,Rules0,Rules) :-
	( chr_pp_flag(show,on) ->
		Constraints = ['$show'/0|Constraints0],
		generate_show_rules(Constraints0,Rules,[Rule|Rules0]),
		inc_rule_count(RuleNb),
		Rule = pragma(
				rule(['$show'],[],true,true),
				ids([0],[]),
				[],
				no,
				RuleNb
			)
	;
		Constraints = Constraints0,
		Rules = Rules0
	).

generate_show_rules([],Rules,Rules).
generate_show_rules([F/A|Rest],[Rule|Tail],Rules) :-
	functor(C,F,A),
	inc_rule_count(RuleNb),
	Rule = pragma(
			rule([],['$show',C],true,writeln(C)),
			ids([],[0,1]),
			[passive(1)],
			no,
			RuleNb
		),
	generate_show_rules(Rest,Tail,Rules).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Custom supension term layout

static_suspension_term(F/A,Suspension) :-
	suspension_term_base(F/A,Base),
	Arity is Base + A,
	functor(Suspension,suspension,Arity).

has_suspension_field(FA,Field) :-
	suspension_term_base_fields(FA,Fields),
	memberchk(Field,Fields).

suspension_term_base(FA,Base) :-
	suspension_term_base_fields(FA,Fields),
	length(Fields,Base).

suspension_term_base_fields(FA,Fields) :-
	( chr_pp_flag(debugable,on) ->
		% 1. ID
		% 2. State
		% 3. Propagation History
		% 4. Generation Number
		% 5. Continuation Goal
		% 6. Functor
		Fields = [id,state,history,generation,continuation,functor]
	;
		( uses_history(FA) ->
			Fields = [id,state,history|Fields2]
		; only_ground_indexed_arguments(FA), get_functional_dependency(FA,1,_,_) ->
			Fields = [state|Fields2]
		;
			Fields = [id,state|Fields2]
		),
		( only_ground_indexed_arguments(FA) ->
			get_store_type(FA,StoreType),
			basic_store_types(StoreType,BasicStoreTypes),
			( memberchk(global_ground,BasicStoreTypes) ->
				% 1. ID
				% 2. State
				% 3. Propagation History
				% 4. Global List Prev
				Fields2 = [global_list_prev|Fields3]
			;
				% 1. ID
				% 2. State
				% 3. Propagation History
				Fields2 = Fields3
			),
			(   chr_pp_flag(ht_removal,on)
			->  ht_prev_fields(BasicStoreTypes,Fields3)
			;   Fields3 = []
			)
		; may_trigger(FA) ->
			% 1. ID
			% 2. State
			% 3. Propagation History
			( uses_field(FA,generation) ->
			% 4. Generation Number
			% 5. Global List Prev
				Fields2 = [generation,global_list_prev|Fields3]
			;
				Fields2 = [global_list_prev|Fields3]
			),
			(   chr_pp_flag(mixed_stores,on),
			    chr_pp_flag(ht_removal,on)
			->  get_store_type(FA,StoreType),
			    basic_store_types(StoreType,BasicStoreTypes),
			    ht_prev_fields(BasicStoreTypes,Fields3)
			;   Fields3 = []
			)
		;
			% 1. ID
			% 2. State
			% 3. Propagation History
			% 4. Global List Prev
			Fields2 = [global_list_prev|Fields3],
			(   chr_pp_flag(mixed_stores,on),
			    chr_pp_flag(ht_removal,on)
			->  get_store_type(FA,StoreType),
			    basic_store_types(StoreType,BasicStoreTypes),
			    ht_prev_fields(BasicStoreTypes,Fields3)
			;   Fields3 = []
			)
		)
	).

ht_prev_fields(Stores,Prevs) :-
	ht_prev_fields_int(Stores,PrevsList),
	append(PrevsList,Prevs).
ht_prev_fields_int([],[]).
ht_prev_fields_int([H|T],Fields) :-
	(   H = multi_hash(Indexes)
	->  maplist(ht_prev_field,Indexes,FH),
	    Fields = [FH|FT]
	;   Fields = FT
	),
	ht_prev_fields_int(T,FT).

ht_prev_field(Index,Field) :-
	concat_atom(['multi_hash_prev-'|Index],Field).

get_static_suspension_term_field(FieldName,FA,StaticSuspension,Field) :-
	suspension_term_base_fields(FA,Fields),
	nth1(Index,Fields,FieldName), !,
	arg(Index,StaticSuspension,Field).
get_static_suspension_term_field(arguments,FA,StaticSuspension,Field) :- !,
	suspension_term_base(FA,Base),
	StaticSuspension =.. [_|Args],
	drop(Base,Args,Field).
get_static_suspension_term_field(FieldName,FA,_StaticSuspension,_Field) :-
	chr_error(internal,'Trying to obtain field ~w of ~w, wich does not have it!',[FieldName,FA]).


get_dynamic_suspension_term_field(FieldName,FA,DynamicSuspension,Field,Goal) :-
	suspension_term_base_fields(FA,Fields),
	nth1(Index,Fields,FieldName), !,
	Goal = arg(Index,DynamicSuspension,Field).
get_dynamic_suspension_term_field(arguments,FA,DynamicSuspension,Field,Goal) :- !,
	static_suspension_term(FA,StaticSuspension),
	get_static_suspension_term_field(arguments,FA,StaticSuspension,Field),
	Goal = (DynamicSuspension = StaticSuspension).
get_dynamic_suspension_term_field(argument(I),FA,DynamicSuspension,Field,Goal) :- !,
	suspension_term_base(FA,Base),
	Index is I + Base,
	Goal = arg(Index,DynamicSuspension,Field).
get_dynamic_suspension_term_field(FieldName,FA,_DynamicSuspension,_Field,_Goal) :-
	chr_error(internal,'Dynamic goal to get ~w of ~w, which does not have this field!',[FieldName,FA]).


set_dynamic_suspension_term_field(FieldName,FA,DynamicSuspension,Field,Goal) :-
	suspension_term_base_fields(FA,Fields),
	nth1(Index,Fields,FieldName), !,
	Goal = setarg(Index,DynamicSuspension,Field).
set_dynamic_suspension_term_field(FieldName,FA,_DynamicSuspension,_Field,_Goal) :-
	chr_error(internal,'Dynamic goal to set ~w of ~w, which does not have this field!',[FieldName,FA]).

basic_store_types(multi_store(Types),Types) :- !.
basic_store_types(Type,[Type]).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%

:- chr_constraint
        phase_end/1,
        delay_phase_end/2.

:- chr_option(mode,phase_end(+)).
:- chr_option(mode,delay_phase_end(+,?)).

phase_end(Phase) \ delay_phase_end(Phase,Goal) <=> call(Goal).
% phase_end(Phase) <=> true.


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
:- chr_constraint
	does_use_history/2,
	uses_history/1,
	novel_production_call/4.

:- chr_option(mode,uses_history(+)).
:- chr_option(mode,does_use_history(+,+)).
:- chr_option(mode,novel_production_call(+,+,?,?)).

does_use_history(FA,Occ) \ does_use_history(FA,Occ) <=> true.
does_use_history(FA,_) \ uses_history(FA) <=> true.
uses_history(_FA) <=> fail.

does_use_history(FA,Occ) \ novel_production_call(FA,Occ,PossibleGoal,Goal) <=> Goal = PossibleGoal.
novel_production_call(FA,_,_PossibleGoal,Goal) <=> Goal = true.

:- chr_constraint
	does_use_field/2,
	uses_field/2.

:- chr_option(mode,uses_field(+,+)).
:- chr_option(mode,does_use_field(+,+)).

does_use_field(FA,Field) \ does_use_field(FA,Field) <=> true.
does_use_field(FA,Field) \ uses_field(FA,Field) <=> true.
uses_field(_FA,_Field) <=> fail.

:- chr_constraint
	uses_state/2,
	if_used_state/5,
	used_states_known/0.

:- chr_option(mode,uses_state(+,+)).
:- chr_option(mode,if_used_state(+,+,?,?,?)).


% states ::= not_stored_yet | passive | active | triggered | removed
%
% allocate CREATES not_stored_yet
%   remove CHECKS  not_stored_yet
% activate CHECKS  not_stored_yet
%
%  ==> no allocate THEN no not_stored_yet

% recurs   CREATES inactive
% lookup   CHECKS  inactive

% insert   CREATES active
% activate CREATES active
% lookup   CHECKS  active
% recurs   CHECKS  active

% runsusp  CREATES triggered
% lookup   CHECKS  triggered
%
% ==> no runsusp THEN no triggered

% remove   CREATES removed
% runsusp  CHECKS  removed
% lookup   CHECKS  removed
% recurs   CHECKS  removed
%
% ==> no remove THEN no removed

% ==> no allocate, no remove, no active/inactive distinction THEN no state at all...

uses_state(Constraint,State) \ uses_state(Constraint,State) <=> true.

used_states_known, uses_state(Constraint,State) \ if_used_state(Constraint,State,Used,NotUsed,ResultGoal)
        <=> ResultGoal = Used.
used_states_known \ if_used_state(Constraint,State,Used,NotUsed,ResultGoal)
        <=> ResultGoal = NotUsed.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% CHECK STOREDNESS ANNOTATIONS AND GENERATE DEFAULT SIMPLIFICATION RULES
% (Feature for SSS)
%
% 1. Checking
% ~~~~~~~~~~~
%
% When the programmer enables the `declare_stored_constraints' option, i.e. writes
%
%	:- chr_option(declare_stored_constraints,on).
%
% the compiler will check for the storedness of constraints.
%
% By default, the compiler assumes that the programmer wants his constraints to
% be never-stored. Hence, a warning will be issues when a constraint is actually
% stored.
%
% Such warnings are suppressed, if the programmer adds the `# stored' modifier
% to a constraint declaration, i.e. writes
%
%	:- chr_constraint c(...) # stored.
%
% In that case a warning is issued when the constraint is never-stored.
%
% NOTE: Checking is only performed if `storage_analysis' is on. Otherwise, all
%       constraints are stored anyway.
%
%
% 2. Rule Generation
% ~~~~~~~~~~~~~~~~~~
%
% When the programmer enables the `declare_stored_constraints' option, i.e. writes
%
%	:- chr_option(declare_stored_constraints,on).
%
% the compiler will generate default simplification rules for constraints.
%
% By default, no default rule is generated for a constraint. However, if the
% programmer writes a default/1 annotation in the constraint declaration, i.e. writes
%
%	:- chr_constraint c(...) # default(Goal).
%
% where `Goal' is a ground and callable goal (e.g. `true', `fail' or `throw(error)'),
% the compiler generates a rule:
%
%		c(_,...,_) <=> Goal.
%
% at the end of the program. If multiple default rules are generated, for several constraints,
% then the order of the default rules is not specified.


:- chr_constraint stored_assertion/1.
:- chr_option(mode,stored_assertion(+)).
:- chr_option(type_declaration,stored_assertion(constraint)).

:- chr_constraint never_stored_default/2.
:- chr_option(mode,never_stored_default(+,?)).
:- chr_option(type_declaration,never_stored_default(constraint,any)).

% Rule Generation
% ~~~~~~~~~~~~~~~

generate_never_stored_rules(Constraints,Rules) :-
	( chr_pp_flag(declare_stored_constraints,on) ->
		never_stored_rules(Constraints,Rules)
	;
		Rules = []
	).

:- chr_constraint never_stored_rules/2.
:- chr_option(mode,never_stored_rules(+,?)).
:- chr_option(type_declaration,never_stored_rules(list(constraint),any)).

never_stored_rules([],Rules) <=> Rules = [].
never_stored_default(Constraint,Goal) \ never_stored_rules([Constraint|Constraints],Rules) <=>
	Constraint = F/A,
	functor(Head,F,A),
	inc_rule_count(RuleNb),
	Rule = pragma(
			rule([Head],[],true,Goal),
			ids([0],[]),
			[],
			no,
			RuleNb
		),
	Rules = [Rule|Tail],
	never_stored_rules(Constraints,Tail).
never_stored_rules([_|Constraints],Rules) <=>
	never_stored_rules(Constraints,Rules).

% Checking
% ~~~~~~~~

check_storedness_assertions(Constraints) :-
	( chr_pp_flag(storage_analysis,on), chr_pp_flag(declare_stored_constraints,on) ->
		forall(Constraint,Constraints,check_storedness_assertion(Constraint))
	;
		true
	).


:- chr_constraint check_storedness_assertion/1.
:- chr_option(mode,check_storedness_assertion(+)).
:- chr_option(type_declaration,check_storedness_assertion(constraint)).

check_storedness_assertion(Constraint), stored_assertion(Constraint)
	<=> ( is_stored(Constraint) ->
		true
	    ;
		chr_warning(assertion_failed,'Constraint ~w is not stored. However, it was asserted to be stored.\n',[Constraint])
	    ).
never_stored_default(Constraint,_) \ check_storedness_assertion(Constraint)
	<=> ( is_finally_stored(Constraint) ->
		chr_warning(assertion_failed,'Constraint ~w is stored. However, it was asserted not to be stored.\n',[Constraint])
	    ; is_stored(Constraint) ->
		chr_warning(assertion_failed,'Constraint ~w is temporarily stored. However, it was asserted not to be stored.\n',[Constraint])
	    ;
		true
	    ).
	% never-stored, no default goal
check_storedness_assertion(Constraint)
	<=> ( is_finally_stored(Constraint) ->
		chr_warning(assertion_failed,'Constraint ~w is stored. However, it was asserted not to be stored.\n',[Constraint])
	    ; is_stored(Constraint) ->
		chr_warning(assertion_failed,'Constraint ~w is temporarily stored. However, it was asserted not to be stored.\n',[Constraint])
	    ;
		true
	    ).

%^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
% success continuation analysis

% TODO
%	also use for forward jumping improvement!
%	use Prolog indexing for generated code
%
% EXPORTED
%
%	should_skip_to_next_id(C,O)
%
%	get_occurrence_code_id(C,O,Id)
%
%vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv

continuation_analysis(ConstraintSymbols) :-
	maplist(analyse_continuations,ConstraintSymbols).

analyse_continuations(C) :-
	% 1. compute success continuations of the
	%    occurrences of constraint C
	continuation_analysis(C,1),
	% 2. determine for which occurrences
	%    to skip to next code id
	get_max_occurrence(C,MO),
	LO is MO + 1,
	bulk_propagation(C,1,LO),
	% 3. determine code id for each occurrence
	set_occurrence_code_id(C,1,0).

% 1. Compute the success continuations of constrait C
%-------------------------------------------------------------------------------

continuation_analysis(C,O) :-
	get_max_occurrence(C,MO),
	( O > MO ->
		true
	; O == MO ->
		NextO is O + 1,
		continuation_occurrence(C,O,NextO)
	;
		constraint_continuation(C,O,MO,NextO),
		continuation_occurrence(C,O,NextO),
		NO is O + 1,
		continuation_analysis(C,NO)
	).

constraint_continuation(C,O,MO,NextO) :-
	( get_occurrence_head(C,O,Head) ->
		NO is O + 1,
		( between(NO,MO,NextO),
		  get_occurrence_head(C,NextO,NextHead),
		  unifiable(Head,NextHead,_) ->
			true
		;
			NextO is MO + 1
		)
	; % current occurrence is passive
		NextO = MO
	).

get_occurrence_head(C,O,Head) :-
	get_occurrence(C,O,RuleNb,Id),
	\+ is_passive(RuleNb,Id),
	get_rule(RuleNb,Rule),
	Rule = pragma(rule(H1,H2,_,_),ids(Ids1,Ids2),_,_,_),
	( select2(Id,Head,Ids1,H1,_,_) -> true
	; select2(Id,Head,Ids2,H2,_,_)
	).

:- chr_constraint continuation_occurrence/3.
:- chr_option(mode,continuation_occurrence(+,+,+)).

:- chr_constraint get_success_continuation_occurrence/3.
:- chr_option(mode,get_success_continuation_occurrence(+,+,-)).

continuation_occurrence(C,O,NO) \ get_success_continuation_occurrence(C,O,X)
	<=>
		X = NO.

get_success_continuation_occurrence(C,O,X)
	<=>
		chr_error(internal,'Success continuation not found for ~w.\n',[C:O]).

% 2. figure out when to skip to next code id
%-------------------------------------------------------------------------------
	% don't go beyond the last occurrence
	% we have to go to next id for storage here

:- chr_constraint skip_to_next_id/2.
:- chr_option(mode,skip_to_next_id(+,+)).

:- chr_constraint should_skip_to_next_id/2.
:- chr_option(mode,should_skip_to_next_id(+,+)).

skip_to_next_id(C,O) \ should_skip_to_next_id(C,O)
	<=>
		true.

should_skip_to_next_id(_,_)
	<=>
		fail.

:- chr_constraint bulk_propagation/3.
:- chr_option(mode,bulk_propagation(+,+,+)).

max_occurrence(C,MO) \ bulk_propagation(C,O,_)
	<=>
		O >= MO
	|
		skip_to_next_id(C,O).
	% we have to go to the next id here because
	% a predecessor needs it
bulk_propagation(C,O,LO)
	<=>
		LO =:= O + 1
	|
		skip_to_next_id(C,O),
		get_max_occurrence(C,MO),
		NLO is MO + 1,
		bulk_propagation(C,LO,NLO).
	% we have to go to the next id here because
	% we're running into a simplification rule
	% IMPROVE: propagate back to propagation predecessor (IF ANY)
occurrence(C,NO,_,_,simplification) \ bulk_propagation(C,O,LO)
	<=>
		NO =:= O + 1
	|
		skip_to_next_id(C,O),
		get_max_occurrence(C,MO),
		NLO is MO + 1,
		bulk_propagation(C,NO,NLO).
	% we skip the next id here
	% and go to the next occurrence
continuation_occurrence(C,O,NextO) \ bulk_propagation(C,O,LO)
	<=>
		NextO > O + 1
	|
		NLO is min(LO,NextO),
		NO is O + 1,
		bulk_propagation(C,NO,NLO).
	% default case
	% err on the safe side
bulk_propagation(C,O,LO)
	<=>
		skip_to_next_id(C,O),
		get_max_occurrence(C,MO),
		NLO is MO + 1,
		NO is O + 1,
		bulk_propagation(C,NO,NLO).

skip_to_next_id(C,O) \ skip_to_next_id(C,O) <=> true.

	% if this occurrence is passive, but has to skip,
	% then the previous one must skip instead...
	% IMPROVE reasoning is conservative
occurrence(C,O,RuleNb,Id,_), passive(RuleNb,Id), skip_to_next_id(C,O)
	==>
		O > 1
	|
		PO is O - 1,
		skip_to_next_id(C,PO).

% 3. determine code id of each occurrence
%-------------------------------------------------------------------------------

:- chr_constraint set_occurrence_code_id/3.
:- chr_option(mode,set_occurrence_code_id(+,+,+)).

:- chr_constraint occurrence_code_id/3.
:- chr_option(mode,occurrence_code_id(+,+,+)).

	% stop at the end
set_occurrence_code_id(C,O,IdNb)
	<=>
		get_max_occurrence(C,MO),
		O > MO
	|
		occurrence_code_id(C,O,IdNb).

	% passive occurrences don't change the code id
occurrence(C,O,RuleNb,Id,_), passive(RuleNb,Id) \ set_occurrence_code_id(C,O,IdNb)
	<=>
		occurrence_code_id(C,O,IdNb),
		NO is O + 1,
		set_occurrence_code_id(C,NO,IdNb).

occurrence(C,O,RuleNb,Id,simplification) \ set_occurrence_code_id(C,O,IdNb)
	<=>
		occurrence_code_id(C,O,IdNb),
		NO is O + 1,
		set_occurrence_code_id(C,NO,IdNb).

occurrence(C,O,RuleNb,Id,propagation), skip_to_next_id(C,O) \ set_occurrence_code_id(C,O,IdNb)
	<=>
		occurrence_code_id(C,O,IdNb),
		NO    is O    + 1,
		NIdNb is IdNb + 1,
		set_occurrence_code_id(C,NO,NIdNb).

occurrence(C,O,RuleNb,Id,propagation) \ set_occurrence_code_id(C,O,IdNb)
	<=>
		occurrence_code_id(C,O,IdNb),
		NO is O + 1,
		set_occurrence_code_id(C,NO,IdNb).

% occurrence_code_id(C,O,IdNb) ==> writeln(occurrence_code_id(C,O,IdNb)).

:- chr_constraint get_occurrence_code_id/3.
:- chr_option(mode,get_occurrence_code_id(+,+,-)).

occurrence_code_id(C,O,IdNb) \ get_occurrence_code_id(C,O,X)
	<=>
		X = IdNb.

get_occurrence_code_id(C,O,X)
	<=>
		( O == 0 ->
			true % X = 0
		;
			format('no occurrence code for ~w!\n',[C:O])
		).

get_success_continuation_code_id(C,O,NextId) :-
	get_success_continuation_occurrence(C,O,NextO),
	get_occurrence_code_id(C,NextO,NextId).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% COLLECT CONSTANTS FOR INLINING
%
% for SSS

%%% TODO: APPLY NEW DICT FORMAT DOWNWARDS

% collect_constants(+rules,+ast_rules,+constraint_symbols,+clauses) {{{
collect_constants(Rules,AstRules,Constraints,Clauses0) :-
	( not_restarted, chr_pp_flag(experiment,on) ->
		( chr_pp_flag(sss,on) ->
				Dictionary = [fep/4-[2,3]-[[a,b]-fep1,[c,d]-fep2]-no],
				copy_term_nat(Clauses0,Clauses),
				flatten_clauses(Clauses,Dictionary,FlatClauses),
				install_new_declarations_and_restart(FlatClauses)
		;
			maplist(collect_rule_constants(Constraints),AstRules),
			( chr_pp_flag(verbose,on) ->
				print_chr_constants
			;
				true
			),
			( chr_pp_flag(experiment,on) ->
				flattening_dictionary(Constraints,Dictionary),
				copy_term_nat(Clauses0,Clauses),
				flatten_clauses(Clauses,Dictionary,FlatClauses),
				install_new_declarations_and_restart(FlatClauses)
			;
				true
			)
		)
	;
		true
	).

:- chr_constraint chr_constants/1.
:- chr_option(mode,chr_constants(+)).

:- chr_constraint get_chr_constants/1.

chr_constants(Constants) \ get_chr_constants(Q) <=> Q = Constants.

get_chr_constants(Q) <=> chr_warning(internal,'No constants found for key ~w.\n',[Key]), Q = [].

% collect_rule_constants(+constraint_symbols,+ast_rule) {{{
collect_rule_constants(Constraints,AstRule) :-
	AstRule = ast_rule(AstHead,_,_,AstBody,_),
	collect_head_constants(AstHead),
	collect_body_constants(AstBody,Constraints).

collect_head_constants(simplification(H1)) :-
	maplist(collect_constraint_constants,H1).
collect_head_constants(propagation(H2)) :-
	maplist(collect_constraint_constants,H2).
collect_head_constants(simpagation(H1,H2)) :-
	maplist(collect_constraint_constants,H1),
	maplist(collect_constraint_constants,H2).

collect_body_constants(AstBody,Constraints) :-
	maplist(collect_goal_constants(Constraints),AstBody).

collect_goal_constants(Constraints,Goal) :-
	( ast_nonvar(Goal) ->
		ast_symbol(Goal,Symbol),
		( memberchk(Symbol,Constraints) ->
			ast_term_to_term(Goal,Term),
			ast_args(Goal,Arguments),
			collect_constraint_constants(chr_constraint(Symbol,Arguments,Term))
		; Symbol == (:)/2,
		  ast_args(Goal,[Arg1,Goal2]),
		  Arg1 = atomic(Mod),
		  get_target_module(Module),
		  Mod == Module,
		  ast_nonvar(Goal2),
		  ast_symbol(Goal2,Symbol2),
		  memberchk(Symbol2,Constraints) ->
			ast_term_to_term(Goal2,Term2),
			ast_args(Goal2,Arguments2),
			collect_constraint_constants(chr_constraint(Symbol2,Arguments2,Term2))
		;
			true
		)
	;
		true
	).

collect_constraint_constants(Head) :-
	Head = chr_constraint(Symbol,Arguments,_),
	get_constraint_type_det(Symbol,Types),
	collect_all_arg_constants(Arguments,Types,[]).

collect_all_arg_constants([],[],Constants) :-
	( Constants \== [] ->
		add_chr_constants(Constants)
	;
		true
	).
collect_all_arg_constants([Arg|Args],[Type|Types],Constants0) :-
	unalias_type(Type,NormalizedType),
	( is_chr_constants_type(NormalizedType,Key,_) ->
		( ast_ground(Arg) ->
			ast_term_to_term(Arg,Term),
			collect_all_arg_constants(Args,Types,[Key-Term|Constants0])
		; % no useful information here
			true
		)
	;
		collect_all_arg_constants(Args,Types,Constants0)
	).

add_chr_constants(Pairs) :-
	keysort(Pairs,SortedPairs),
	add_chr_constants_(SortedPairs).

:- chr_constraint add_chr_constants_/1.
:- chr_option(mode,add_chr_constants_(+)).

add_chr_constants_(Constants), chr_constants(MoreConstants) <=>
	sort([Constants|MoreConstants],NConstants),
	chr_constants(NConstants).

add_chr_constants_(Constants) <=>
	chr_constants([Constants]).

% }}}

:- chr_constraint print_chr_constants/0. % {{{

print_chr_constants, chr_constants(Constants) # Id ==>
	format('\t* chr_constants : ~w.\n',[Constants])
	pragma passive(Id).

print_chr_constants <=>
	true.

% }}}

% flattening_dictionary(+constraint_symbols,-dictionary) {{{
flattening_dictionary([],[]).
flattening_dictionary([CS|CSs],Dictionary) :-
	( flattening_dictionary_entry(CS,Entry) ->
		Dictionary = [Entry|Rest]
	;
		Dictionary = Rest
	),
	flattening_dictionary(CSs,Rest).

flattening_dictionary_entry(CS,Entry) :-
	get_constraint_type_det(CS,Types),
	constant_positions(Types,1,Positions,Keys,Handler,MaybeEnum),
	( Positions \== [] ->					% there are chr_constant arguments
		pairup(Keys,Constants,Pairs0),
		keysort(Pairs0,Pairs),
		Entry = CS-Positions-Specs-Handler,
		get_chr_constants(ConstantsList),
		findall(Spec,
				( member(Pairs,ConstantsList)
				, flat_spec(CS,Positions,Constants,Spec)
				),
			Specs)
	; MaybeEnum == yes ->
		enum_positions(Types,1,EnumPositions,ConstantsLists,EnumHandler),
		Entry = CS-EnumPositions-Specs-EnumHandler,
		findall(Spec,
				( cartesian_product(Terms,ConstantsLists)
				, flat_spec(CS,EnumPositions,Terms,Spec)
				),
			Specs)
	).

constant_positions([],_,[],[],no,no).
constant_positions([Type|Types],I,Positions,Keys,Handler,MaybeEnum) :-
	unalias_type(Type,NormalizedType),
	( is_chr_constants_type(NormalizedType,Key,ErrorHandler) ->
		compose_error_handlers(ErrorHandler,NHandler,Handler),
		Positions = [I|NPositions],
		Keys = [Key|NKeys],
		MaybeEnum = NMaybeEnum
	;
		( is_chr_enum_type(NormalizedType,_,_) ->
			MaybeEnum = yes
		;
			MaybeEnum = NMaybeEnum
		),
		NPositions = Positions,
		NKeys = Keys,
		NHandler = Handler
	),
	J is I + 1,
	constant_positions(Types,J,NPositions,NKeys,NHandler,NMaybeEnum).

compose_error_handlers(no,Handler,Handler).
compose_error_handlers(yes(Handler),_,yes(Handler)).

enum_positions([],_,[],[],no).
enum_positions([Type|Types],I,Positions,ConstantsLists,Handler) :-
	unalias_type(Type,NormalizedType),
	( is_chr_enum_type(NormalizedType,Constants,ErrorHandler) ->
		compose_error_handlers(ErrorHandler,NHandler,Handler),
		Positions      = [I|NPositions],
		ConstantsLists = [Constants|NConstantsLists]
	;	Positions      = NPositions,
		ConstantsLists = NConstantsLists,
		Handler	       = NHandler
	),
	J is I + 1,
	enum_positions(Types,J,NPositions,NConstantsLists,NHandler).

cartesian_product([],[]).
cartesian_product([E|Es],[L|Ls]) :-
	member(E,L),
	cartesian_product(Es,Ls).

flat_spec(C/N,Positions,Terms,Spec) :-
	Spec = Terms - Functor,
	term_to_atom(Terms,TermsAtom),
	term_to_atom(Positions,PositionsAtom),
	atom_concat_list(['$flat_',C,'/',N,'___',PositionsAtom,'___',TermsAtom],Functor).

% }}}

% }}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% RESTART AFTER FLATTENING {{{

restart_after_flattening(Declarations,Declarations) :-
	nb_setval('$chr_restart_after_flattening',started).
restart_after_flattening(_,Declarations) :-
	nb_getval('$chr_restart_after_flattening',restart(Declarations)),
	nb_setval('$chr_restart_after_flattening',restarted).

not_restarted :-
	nb_getval('$chr_restart_after_flattening',started).

install_new_declarations_and_restart(Declarations) :-
	nb_setval('$chr_restart_after_flattening',restart(Declarations)),
	fail. /* fails to choicepoint of restart_after_flattening */
% }}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% FLATTENING {{{

% DONE
%	-) generate dictionary from collected chr_constants
%	   enable with :- chr_option(experiment,on).
%	-) issue constraint declarations for constraints not present in
%	   dictionary
%	-) integrate with CHR compiler
%	-) pass Mike's test code (full syntactic support for current CHR code)
%	-) rewrite the body using the inliner
%
% TODO:
%	-) refined semantics correctness issue
%	-) incorporate chr_enum into dictionary generation
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

flatten_clauses(Clauses,Dict,NClauses) :-
	flatten_readcontent(Clauses,Rules,Symbols,ModeDecls,_TypeDefs,TypeDecls,RestClauses),
	flatten_clauses_(Dict,Rules,RestClauses,Symbols,ModeDecls,TypeDecls,NClauses).

flatten_clauses_(Dict,Clauses,RestClauses,Symbols,ModeDecls,TypeDecls,NClauses) :-
	auxiliary_constraints_declarations(Dict,ModeDecls,TypeDecls,NClauses0),
	dispatching_rules(Dict,NClauses1),
	declarations(Symbols,Dict,ModeDecls,TypeDecls,NClauses2),
	flatten_rules(Clauses,Dict,NClauses3),
	append([RestClauses,NClauses0,NClauses1,NClauses2,NClauses3],NClauses).

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
% Declarations for non-flattened constraints

% declarations(+constraint_symbols,+dict,+mode_decls,+type_decls,-clauses) {{{
declarations(ConstraintSymbols,Dict,ModeDecls,TypeDecls,Declarations) :-
	findall(Symbol,(member(Symbol,ConstraintSymbols), \+ memberchk(Symbol-_-_-_,Dict)),Symbols),
	maplist(declaration(ModeDecls,TypeDecls),Symbols,DeclarationsList),
	flatten(DeclarationsList,Declarations).

declaration(ModeDecls,TypeDecls,ConstraintSymbol,
	[(:- chr_constraint ConstraintSymbol),
	 (:- chr_option(mode,ModeDeclPattern)),
         (:- chr_option(type_declaration,TypeDeclPattern))
	]) :-
	ConstraintSymbol = Functor / Arity,
	% print optional mode declaration
	functor(ModeDeclPattern,Functor,Arity),
	( memberchk(ModeDeclPattern,ModeDecls) ->
		true
	;
		replicate(Arity,(?),Modes),
		ModeDeclPattern =.. [_|Modes]
	),
	% print optional type declaration
	functor(TypeDeclPattern,Functor,Arity),
	( memberchk(TypeDeclPattern,TypeDecls) ->
		true
	;
		replicate(Arity,any,Types),
		TypeDeclPattern =.. [_|Types]
	).
% }}}
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
% read clauses from file
%	CHR			are	returned
%	declared constaints	are	returned
%	type definitions	are	returned and printed
%	mode declarations	are	returned
%	other clauses		are	returned

% flatten_readcontent(+clauses,-rules,-symbols,-mode_decls,-type_defs,-type_decls,-rest_clauses) {{{
flatten_readcontent([],[],[],[],[],[],[]).
flatten_readcontent([Clause|RClauses],Rules,ConstraintSymbols,ModeDecls,TypeDefs,TypeDecls,RestClauses) :-
	% read(Clause),
        ( Clause == end_of_file ->
                Rules			= [],
		ConstraintSymbols	= [],
		ModeDecls		= [],
		TypeDecls		= [],
		TypeDefs		= [],
		RestClauses		= []
        ; crude_is_rule(Clause) ->
		Rules = [Clause|RestRules],
		flatten_readcontent(RClauses,RestRules,ConstraintSymbols,ModeDecls,TypeDefs,TypeDecls,RestClauses)
	; pure_is_declaration(Clause,SomeConstraintSymbols,SomeModeDecls,SomeTypeDecls) ->
		append(SomeConstraintSymbols,RestConstraintSymbols,ConstraintSymbols),
		append(SomeModeDecls,RestModeDecls,ModeDecls),
		append(SomeTypeDecls,RestTypeDecls,TypeDecls),
		flatten_readcontent(RClauses,Rules,RestConstraintSymbols,RestModeDecls,TypeDefs,RestTypeDecls,RestClauses)
	; is_mode_declaration(Clause,ModeDecl) ->
		ModeDecls = [ModeDecl|RestModeDecls],
		flatten_readcontent(RClauses,Rules,ConstraintSymbols,RestModeDecls,TypeDefs,TypeDecls,RestClauses)
	; is_type_declaration(Clause,TypeDecl) ->
		TypeDecls = [TypeDecl|RestTypeDecls],
		flatten_readcontent(RClauses,Rules,ConstraintSymbols,ModeDecls,TypeDefs,RestTypeDecls,RestClauses)
	; is_type_definition(Clause,TypeDef) ->
		RestClauses = [Clause|NRestClauses],
		TypeDefs = [TypeDef|RestTypeDefs],
		flatten_readcontent(RClauses,Rules,ConstraintSymbols,ModeDecls,RestTypeDefs,TypeDecls,NRestClauses)
	;	( Clause = (:- op(A,B,C)) ->
			% assert operators in order to read and print them out properly
			op(A,B,C)
		;
			true
		),
		RestClauses = [Clause|NRestClauses],
                flatten_readcontent(RClauses,Rules,ConstraintSymbols,ModeDecls,TypeDefs,TypeDecls,NRestClauses)
        ).

crude_is_rule((_ @ _)).
crude_is_rule((_ pragma _)).
crude_is_rule((_ ==> _)).
crude_is_rule((_ <=> _)).

pure_is_declaration(D, Constraints,Modes,Types) :-		%% constraint declaration
	D = (:- Decl), Decl =.. [F,Cs], F == (chr_constraint),
	conj2list(Cs,Constraints0),
	pure_extract_type_mode(Constraints0,Constraints,Modes,Types).

pure_extract_type_mode([],[],[],[]).
pure_extract_type_mode([F/A|R],[F/A|R2],Modes,Types) :- !,
	pure_extract_type_mode(R,R2,Modes,Types).
pure_extract_type_mode([C|R],[ConstraintSymbol|R2],[Mode|Modes],Types) :-
	functor(C,F,A),
	ConstraintSymbol = F/A,
	C =.. [_|Args],
	extract_types_and_modes(Args,ArgTypes,ArgModes),
	Mode =.. [F|ArgModes],
	( forall(member(ArgType,ArgTypes),ArgType == any) ->
		Types = RTypes
	;
		Types = [Type|RTypes],
		Type =.. [F|ArgTypes]
	),
	pure_extract_type_mode(R,R2,Modes,RTypes).

is_mode_declaration((:- chr_option(mode,ModeDecl)),ModeDecl).

is_type_declaration((:- chr_option(type_declaration,TypeDecl)),TypeDecl).
% }}}
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
%  DECLARATIONS FOR FLATTENED CONSTRAINTS
%	including mode and type declarations

% auxiliary_constraints_declarations(+dict,+mode_decls,+type_decls,-constraint_specs) {{{
auxiliary_constraints_declarations(Dict,ModeDecls,TypeDecls,ConstraintSpecs) :-
	findall(ConstraintSpec,auxiliary_constraints_declaration(Dict,ModeDecls,TypeDecls,ConstraintSpec),ConstraintSpecs0),
	flatten(ConstraintSpecs0,ConstraintSpecs).

auxiliary_constraints_declaration(Dict,ModeDecls,TypeDecls,
		[(:- chr_constraint ConstraintSpec),
		 (:- chr_option(mode,NewModeDecl)),
		 (:- chr_option(type_declaration,NewTypeDecl))]) :-
	member(C/N-I-SFs-_,Dict),
	arg_modes(C,N,ModeDecls,Modes),
	specialize_modes(Modes,I,SpecializedModes),
	arg_types(C,N,TypeDecls,Types),
	specialize_types(Types,I,SpecializedTypes),
	length(I,IndexSize),
	AN is N - IndexSize,
	member(_Term-F,SFs),
	ConstraintSpec = F/AN,
	NewModeDecl     =.. [F|SpecializedModes],
	NewTypeDecl	=.. [F|SpecializedTypes].

arg_modes(C,N,ModeDecls,ArgModes) :-
	functor(ConstraintPattern,C,N),
	( memberchk(ConstraintPattern,ModeDecls) ->
		ConstraintPattern =.. [_|ArgModes]
	;
		replicate(N,?,ArgModes)
	).

specialize_modes(Modes,I,SpecializedModes) :-
	split_args(I,Modes,_,SpecializedModes).

arg_types(C,N,TypeDecls,ArgTypes) :-
	functor(ConstraintPattern,C,N),
	( memberchk(ConstraintPattern,TypeDecls) ->
		ConstraintPattern =.. [_|ArgTypes]
	;
		replicate(N,any,ArgTypes)
	).

specialize_types(Types,I,SpecializedTypes) :-
	split_args(I,Types,_,SpecializedTypes).
% }}}
%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
% DISPATCHING RULES
%
% dispatching_rules(+dict,-newrules)


% {{{

% This code generates a decision tree for calling the appropriate specialized
% constraint based on the particular value of the argument the constraint
% is being specialized on.
%
% In case an error handler is provided, the handler is called with the
% unexpected constraint.

dispatching_rules([],[]).
dispatching_rules([CN-I-SFs-MaybeErrorHandler|Dict], DispatchingRules) :-
	constraint_dispatching_rule(SFs,CN,I,MaybeErrorHandler,DispatchingRules,RestDispatchingRules),
	dispatching_rules(Dict,RestDispatchingRules).

constraint_dispatching_rule(SFs,C/N,I,MaybeErrorHandler,Rules,RestRules) :-
	( increasing_numbers(I,1) ->
		/* index on first arguments */
		Rules0 = Rules,
		NCN = C/N
	;
		/* reorder arguments for 1st argument indexing */
		functor(Head,C,N),
		Head =.. [_|Args],
		split_args(I,Args,GroundArgs,OtherArgs),
		append(GroundArgs,OtherArgs,ShuffledArgs),
		atom_concat(C,'_$shuffled',NC),
		Body =.. [NC|ShuffledArgs],
		[(Head :- Body)|Rules0] = Rules,
		NCN = NC / N
	),
	Context = swap(C,I),
	dispatching_rule_term_cases(SFs,I,NCN,MaybeErrorHandler,Context,Rules0,RestRules).

increasing_numbers([],_).
increasing_numbers([X|Ys],X) :-
	Y is X + 1,
	increasing_numbers(Ys,Y).

dispatching_rule_term_cases(SFs,I,NC/N,MaybeErrorHandler,Context,Rules,RestRules) :-
	length(I,IndexLength),
	once(pairup(TermLists,Functors,SFs)),
	maplist(head_tail,TermLists,Heads,Tails),
	Payload is N - IndexLength,
	maplist(wrap_in_functor(dispatching_action),Functors,Actions),
	dispatch_trie_index(Heads,Tails,Payload,MaybeErrorHandler,Context,Actions,NC,Rules,RestRules).

dispatching_action(Functor,PayloadArgs,Goal) :-
	Goal =.. [Functor|PayloadArgs].

dispatch_trie_index(Patterns,MorePatterns,Payload,MaybeErrorHandler,Context,Actions,Prefix,Clauses,Tail) :-
	dispatch_trie_step(Patterns,Prefix,Prefix,MorePatterns,Payload,MaybeErrorHandler,Context,Actions,Clauses,Tail).

dispatch_trie_step([],_,_,_,[],_,_,[],L,L) :- !.
	% length MorePatterns == length Patterns == length Results
dispatch_trie_step(Patterns,Symbol,Prefix,MorePatterns,Payload,MaybeErrorHandler,Context,Actions,Clauses,T) :-
	MorePatterns = [List|_],
	length(List,N),
	aggregate_all(set(F/A),
		( member(Pattern,Patterns),
		  functor(Pattern,F,A)
		),
		FAs),
	N1 is N + 1,
	dispatch_trie_step_cases(FAs,N1,Patterns,MorePatterns,Payload,MaybeErrorHandler,Context,Actions,Symbol,Prefix,Clauses,T).

dispatch_trie_step_cases([],N,_,_,Payload,MaybeErrorHandler,Context,_,Symbol,_,Clauses0,Clauses) :-
	( MaybeErrorHandler = yes(ErrorHandler) ->
		Clauses0 = [ErrorClause|Clauses],
		ErrorClause = (Head :- Body),
		Arity is N + Payload,
		functor(Head,Symbol,Arity),
		reconstruct_original_term(Context,Head,Term),
		Body =.. [ErrorHandler,Term]
	;
		Clauses0 = Clauses
	).
dispatch_trie_step_cases([FA|FAs],N,Pattern,MorePatterns,Payload,MaybeErrorHandler,Context,Actions,Symbol,Prefix,Clauses,Tail) :-
	dispatch_trie_step_case(FA,N,Pattern,MorePatterns,Payload,MaybeErrorHandler,Context,Actions,Symbol,Prefix,Clauses,Clauses1),
	dispatch_trie_step_cases(FAs,N,Pattern,MorePatterns,Payload,MaybeErrorHandler,Context,Actions,Symbol,Prefix,Clauses1,Tail).

dispatch_trie_step_case(F/A,N,Patterns,MorePatterns,Payload,MaybeErrorHandler,Context0,Actions,Symbol,Prefix,[Clause|List],Tail) :-
	Clause = (Head :- Cut, Body),
	( MaybeErrorHandler = yes(_) ->
		Cut = (!)
	;
		Cut = true
	),
	/* Head = Symbol(IndexPattern,V2,...,Vn,Payload) */
	N1 is N  + Payload,
	functor(Head,Symbol,N1),
	arg(1,Head,IndexPattern),
	Head =.. [_,_|RestArgs],
	length(PayloadArgs,Payload),
	once(append(Vs,PayloadArgs,RestArgs)),
	/* IndexPattern = F(...) */
	functor(IndexPattern,F,A),
	Context1 = index_functor(F,A,Context0),
	IndexPattern =.. [_|Args],
	append(Args,RestArgs,RecArgs),
	( RecArgs == PayloadArgs ->
		/* nothing more to match on */
		List = Tail,
		rec_cases(Patterns,_,Actions,F/A,_,_,MoreActions),
		MoreActions = [Action],
		call(Action,PayloadArgs,Body)
	;	/* more things to match on */
		rec_cases(Patterns,MorePatterns,Actions,F/A,Cases,MoreCases,MoreActions),
		( MoreActions = [OneMoreAction] ->
			/* only one more thing to match on */
			MoreCases = [OneMoreCase],
			append([Cases,OneMoreCase,PayloadArgs],RecArgs),
			List = Tail,
			call(OneMoreAction,PayloadArgs,Body)
		;
			/* more than one thing to match on */
			/*	[ x1,..., xn]
				[xs1,...,xsn]
			*/
			pairup(Cases,MoreCases,CasePairs),
			common_pattern(CasePairs,CommonPatternPair,DiffVars,Differences),
			append(Args,Vs,[First|Rest]),
			First-Rest = CommonPatternPair,
			Context2 = gct([First|Rest],Context1),
			fresh_symbol(Prefix,RSymbol),
			append(DiffVars,PayloadArgs,RecCallVars),
			Body =.. [RSymbol|RecCallVars],
			findall(CH-CT,member([CH|CT],Differences),CPairs),
			once(pairup(CHs,CTs,CPairs)),
			dispatch_trie_step(CHs,RSymbol,Prefix,CTs,Payload,MaybeErrorHandler,Context2,MoreActions,List,Tail)
		)
	).


% split(list,int,before,at,after).

split([X|Xs],I,Before,At,After) :-
	( I == 1 ->
		Before	= [],
		At	= X,
		After	= Xs
	;
		J is I - 1,
		Before = [X|RBefore],
		split(Xs,J,RBefore,At,After)
	).

% reconstruct_original_term(Context,CurrentTerm,OriginalTerm)
%
% context	::=	swap(functor,positions)
%		|	index_functor(functor,arity,context)
%		|	gct(Pattern,Context)

reconstruct_original_term(swap(Functor,Positions),Term,OriginalTerm) :-
	functor(Term,_,Arity),
	functor(OriginalTerm,Functor,Arity),
	OriginalTerm =.. [_|OriginalArgs],
	split_args(Positions,OriginalArgs,IndexArgs,OtherArgs),
	Term =.. [_|Args],
	append(IndexArgs,OtherArgs,Args).
reconstruct_original_term(index_functor(Functor,Arity,Context),Term0,OriginalTerm) :-
	Term0 =.. [Predicate|Args],
	split_at(Arity,Args,IndexArgs,RestArgs),
	Index =.. [Functor|IndexArgs],
	Term1 =.. [Predicate,Index|RestArgs],
	reconstruct_original_term(Context,Term1,OriginalTerm).
reconstruct_original_term(gct(PatternList,Context),Term0,OriginalTerm) :-
	copy_term_nat(PatternList,IndexTerms),
	term_variables(IndexTerms,Variables),
	Term0 =.. [Predicate|Args0],
	append(Variables,RestArgs,Args0),
	append(IndexTerms,RestArgs,Args1),
	Term1 =.. [Predicate|Args1],
	reconstruct_original_term(Context,Term1,OriginalTerm).
% }}}

%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
% SUBSTITUTE CONSTRAINT SYMBOL FUNCTORS
%
% flatten_rules(+rule_clauses,+dict,-rule_clauses).
%
% dict :== list(functor/arity-list(int)-list(list(term)-functor)-maybe(error_handler))

% {{{
flatten_rules(Rules,Dict,FlatRules) :-
	flatten_rules1(Rules,Dict,FlatRulesList),
	flatten(FlatRulesList,FlatRules).

flatten_rules1([],_,[]).
flatten_rules1([Rule|Rules],Dict,[FlatRules|FlatRulesList]) :-
	findall(FlatRule,flatten_rule(Rule,Dict,FlatRule),FlatRules),
	flatten_rules1(Rules,Dict,FlatRulesList).

flatten_rule((Name @ Rule),Dict,(Name @ NRule)) :- !,
	flatten_rule(Rule,Dict,NRule).
flatten_rule((Rule pragma Pragmas),Dict,(NRule pragma Pragmas)) :- !,
	flatten_rule(Rule,Dict,NRule).
flatten_rule((H ==> B),Dict,(NH ==> NB)) :- !,
	flatten_heads(H,Dict,NH),
	flatten_body(B,Dict,NB).
flatten_rule((H1 \ H2 <=> B),Dict,(NH1 \ NH2 <=> NB)) :- !,
	flatten_heads((H1,H2),Dict,(NH1,NH2)),
	flatten_body(B,Dict,NB).
flatten_rule((H <=> B),Dict,(NH <=> NB)) :-
	flatten_heads(H,Dict,NH),
	flatten_body(B,Dict,NB).

flatten_heads((H1,H2),Dict,(NH1,NH2)) :- !,
	flatten_heads(H1,Dict,NH1),
	flatten_heads(H2,Dict,NH2).
flatten_heads((H # Annotation),Dict,(NH # Annotation)) :- !,
	flatten_heads(H,Dict,NH).
flatten_heads(H,Dict,NH) :-
	( functor(H,C,N),
	  memberchk(C/N-ArgPositions-SFs-_,Dict) ->
		H =.. [_|AllArgs],
		split_args(ArgPositions,AllArgs,GroundArgs,OtherArgs),
		member(GroundArgs-Name,SFs),
		NH =.. [Name|OtherArgs]
	;
		NH = H
	).

flatten_body((Guard | Body),Dict,(NGuard | NBody)) :- !,
	conj2list(Guard,Guards),
	maplist(flatten_goal(Dict),Guards,NGuards),
	list2conj(NGuards,NGuard),
	conj2list(Body,Goals),
	maplist(flatten_goal(Dict),Goals,NGoals),
	list2conj(NGoals,NBody).
flatten_body(Body,Dict,NBody) :-
	conj2list(Body,Goals),
	maplist(flatten_goal(Dict),Goals,NGoals),
	list2conj(NGoals,NBody).

flatten_goal(Dict,Goal,NGoal) :- var(Goal), !, NGoal = Goal.
flatten_goal(Dict,Goal,NGoal) :-
	( is_specializable_goal(Goal,Dict,ArgPositions)
	->
	  specialize_goal(Goal,ArgPositions,NGoal)
	; Goal = Mod : TheGoal,
	  get_target_module(Module),
	  Mod == Module,
	  nonvar(TheGoal),
	  is_specializable_goal(TheGoal,Dict,ArgPositions)
	->
	  specialize_goal(TheGoal,ArgPositions,NTheGoal),
	  NGoal = Mod : NTheGoal
	; partial_eval(Goal,NGoal)
	->
	  true
	;
		NGoal = Goal
	).

%-------------------------------------------------------------------------------%
% Specialize body/guard goal
%-------------------------------------------------------------------------------%
is_specializable_goal(Goal,Dict,ArgPositions) :-
	functor(Goal,C,N),
	memberchk(C/N-ArgPositions-_-_,Dict),
	args(ArgPositions,Goal,Args),
	ground(Args).

specialize_goal(Goal,ArgPositions,NGoal) :-
	  functor(Goal,C,N),
	  Goal =.. [_|Args],
	  split_args(ArgPositions,Args,GroundTerms,Others),
	  flat_spec(C/N,ArgPositions,GroundTerms,_-Functor),
	  NGoal =.. [Functor|Others].

%-------------------------------------------------------------------------------%
% Partially evaluate predicates
%-------------------------------------------------------------------------------%

%	append([],Y,Z)	>-->	Y = Z
%	append(X,[],Z)  >-->	X = Z
partial_eval(append(L1,L2,L3),NGoal) :-
	( L1 == [] ->
		NGoal = (L3 = L2)
	; L2 == [] ->
		NGoal = (L3 = L1)

	).
%	flatten_path(L1,L2) >--> flatten_path(L1',L2)
%				 where flatten(L1,L1')
partial_eval(flatten_path(L1,L2),NGoal) :-
	nonvar(L1),
	flatten(L1,FlatterL1),
	FlatterL1 \== L1 ->
	NGoal = flatten_path(FlatterL1,L2).


% }}}

% }}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
dump_code(Clauses) :-
	( chr_pp_flag(dump,on) ->
		maplist(portray_clause,Clauses)
	;
		true
	).

chr_banner :-
	chr_info(banner,'\tThe K.U.Leuven CHR System\n\t\tMain Developer:\tTom Schrijvers\n\t\tContributors:\tJon Sneyers, Bart Demoen, Jan Wielemaker\n\t\tCopyright:\tK.U.Leuven, Belgium\n\t\tURL:\t\thttp://www.cs.kuleuven.be/~~toms/CHR/\n',[]).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% LOCKING {{{

chr_none_locked(Vars,Goal) :-
	chr_pp_flag(guard_locks,Flag),
	( Flag == off ->
		Goal = true
	; Flag == on ->
		Goal = 'chr none_locked'( Vars)
	; Flag == error ->
		Goal = 'chr none_error_locked'( Vars)
	).

chr_not_locked(Var,Goal) :-
	chr_pp_flag(guard_locks,Flag),
	( Flag == off ->
		Goal = true
	; Flag == on ->
		Goal = 'chr not_locked'( Var)
	; Flag == error ->
		Goal = 'chr not_error_locked'( Var)
	).

chr_lock(Var,Goal) :-
	chr_pp_flag(guard_locks,Flag),
	( Flag == off ->
		Goal = true
	; Flag == on ->
		Goal = 'chr lock'( Var)
	; Flag == error ->
		Goal = 'chr error_lock'( Var)
	).

chr_unlock(Var,Goal) :-
	chr_pp_flag(guard_locks,Flag),
	( Flag == off ->
		Goal = true
	; Flag == on ->
		Goal = 'chr unlock'( Var)
	; Flag == error ->
		Goal = 'chr unerror_lock'( Var)
	).
% }}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% AST representation
%	each AST representation caches the original term
%
%	ast_term ::=	atomic(Term)
%		 |      compound(Functor,Arity,list(ast_term),Term)
%		 |      var(int,Term)
%			-- unique integer identifier

% Conversion Predicate {{{
:- chr_type var_id == natural.

term_to_ast_term(Term,AstTerm,VarEnv,NVarEnv) :-
	( atomic(Term) ->
		AstTerm = atomic(Term),
		NVarEnv  = VarEnv
	; compound(Term) ->
		functor(Term,Functor,Arity),
		AstTerm = compound(Functor,Arity,AstTerms,Term),
		Term =.. [_|Args],
		maplist_dcg(chr_translate:term_to_ast_term,Args,AstTerms,VarEnv,NVarEnv)
	; var(Term) ->
		var_to_ast_term(Term,VarEnv,AstTerm,NVarEnv)
	).

var_to_ast_term(Var,Env,AstTerm,NVarEnv) :-
	Env = VarDict - VarId,
	( lookup_eq(VarDict,Var,AstTerm) ->
		NVarEnv = Env
	;
		AstTerm = var(VarId,Var),
		NVarId is VarId + 1,
		NVarDict = [Var - AstTerm|VarDict],
		NVarEnv = NVarDict - NVarId
	).

%	ast_constraint ::= chr_constraint(Symbol,Arguments,Constraint)
chr_constraint_to_ast_constraint(CHRConstraint,AstConstraint,VarEnv,NVarEnv) :-
	AstConstraint = chr_constraint(Functor/Arity,AstTerms,CHRConstraint),
	functor(CHRConstraint,Functor,Arity),
	CHRConstraint =.. [_|Arguments],
	maplist_dcg(chr_translate:term_to_ast_term,Arguments,AstTerms,VarEnv,NVarEnv).

%	ast_head       ::= simplification(list(chr_constraint))
%			 | propagation(list(chr_constraint))
%			 | simpagation(list(chr_constraint),list(chr_constraint))

%	head_id	       ::= int

%       ast_guard      ::= list(ast_term)
%       ast_body       ::= list(ast_term)

%	ast_rule       ::= ast_rule(ast_head,ast_guard,guard,ast_body,body)

rule_to_ast_rule(Rule,AstRule) :-
	AstRule = ast_rule(Head,AstGuard,Guard,AstBody,Body),
	Rule = rule(H1,H2,Guard,Body),
	EmptyVarEnv = []-1,
	( H1 == [] ->
		Head = propagation(AstConstraints),
		maplist_dcg(chr_translate:chr_constraint_to_ast_constraint,H2,AstConstraints,EmptyVarEnv,VarEnv1)
	; H2 == [] ->
		Head = simplification(AstConstraints),
		maplist_dcg(chr_translate:chr_constraint_to_ast_constraint,H1,AstConstraints,EmptyVarEnv,VarEnv1)
	;
		Head = simpagation(RemovedAstConstraints,KeptAstConstraints),
		maplist_dcg(chr_translate:chr_constraint_to_ast_constraint,H1,RemovedAstConstraints,EmptyVarEnv,VarEnv0),
		maplist_dcg(chr_translate:chr_constraint_to_ast_constraint,H2,KeptAstConstraints,VarEnv0,VarEnv1)
	),
	conj2list(Guard,GuardList),
	maplist_dcg(chr_translate:term_to_ast_term,GuardList,AstGuard,VarEnv1,VarEnv2),
	conj2list(Body,BodyList),
	maplist_dcg(chr_translate:term_to_ast_term,BodyList,AstBody,VarEnv2,_).

pragma_rule_to_ast_rule(pragma(Rule,_,_,_,_),AstRule) :-
	rule_to_ast_rule(Rule,AstRule).

check_rule_to_ast_rule(Rule) :-
	( rule_to_ast_rule(Rule,AstRule) ->
		writeln(AstRule)
	;
		writeln(failed(rule_to_ast_rule(Rule,AstRule)))
	).

% }}}

% AST Utility Predicates {{{
ast_term_to_term(var(_,Var),Var).
ast_term_to_term(atomic(Atom),Atom).
ast_term_to_term(compound(_,_,_,Compound),Compound).

ast_nonvar(atomic(_)).
ast_nonvar(compound(_,_,_,_)).

ast_ground(atomic(_)).
ast_ground(compound(_,_,Arguments,_)) :-
	maplist(ast_ground,Arguments).

%------------------------------------------------------------------------------%
% Check whether a term is ground, given a set of variables that are ground.
%------------------------------------------------------------------------------%
ast_is_ground(VarSet,AstTerm) :-
	ast_is_ground_(AstTerm,VarSet).

ast_is_ground_(var(VarId,_),VarSet) :-
	tree_set_memberchk(VarId,VarSet).
ast_is_ground_(atomic(_),_).
ast_is_ground_(compound(_,_,Arguments,_),VarSet) :-
	maplist(ast_is_ground(VarSet),Arguments).
%------------------------------------------------------------------------------%

ast_functor(atomic(Atom),Atom,0).
ast_functor(compound(Functor,Arity,_,_),Functor,Arity).

ast_symbol(atomic(Atom),Atom/0).
ast_symbol(compound(Functor,Arity,_,_),Functor/Arity).

ast_args(atomic(_),[]).
ast_args(compound(_,_,Arguments,_),Arguments).

%------------------------------------------------------------------------------%
% Add variables in a term to a given set.
%------------------------------------------------------------------------------%
ast_term_variables(atomic(_),Set,Set).
ast_term_variables(compound(_,_,Args,_),Set,NSet) :-
	ast_term_list_variables(Args,Set,NSet).
ast_term_variables(var(VarId,_),Set,NSet) :-
	tree_set_add(Set,VarId,NSet).

ast_term_list_variables(Terms,Set,NSet) :-
	fold(Terms,chr_translate:ast_term_variables,Set,NSet).
%------------------------------------------------------------------------------%

ast_constraint_variables(chr_constraint(_,Args,_),Set,NSet) :-
	ast_term_list_variables(Args,Set,NSet).

ast_constraint_list_variables(Constraints,Set,NSet) :-
	fold(Constraints,chr_translate:ast_constraint_variables,Set,NSet).

ast_head_variables(simplification(H1),Set,NSet) :-
	ast_constraint_list_variables(H1,Set,NSet).
ast_head_variables(propagation(H2),Set,NSet) :-
	ast_constraint_list_variables(H2,Set,NSet).
ast_head_variables(simpagation(H1,H2),Set,NSet) :-
	ast_constraint_list_variables(H1,Set,Set1),
	ast_constraint_list_variables(H2,Set1,NSet).

ast_var_memberchk(var(VarId,_),Set) :-
	tree_set_memberchk(VarId,Set).

%------------------------------------------------------------------------------%
% Return term based on AST-term with variables mapped.
%------------------------------------------------------------------------------%
ast_instantiate(Map,AstTerm,Term) :-
	ast_instantiate_(AstTerm,Map,Term).

ast_instantiate_(var(VarId,_),Map,Term) :-
	get_assoc(VarId,Map,Term).
ast_instantiate_(atomic(Atom),_,Atom).
ast_instantiate_(compound(Functor,Arity,Arguments,_),Map,Term) :-
	functor(Term,Functor,Arity),
	Term =.. [_|Terms],
	maplist(ast_instantiate(Map),Arguments,Terms).
%------------------------------------------------------------------------------%
% }}}

%------------------------------------------------------------------------------%
% ast_head_arg_matches_(list(silent_pair(ast_term,var)
%                      ,modes
%                      ,map(var_id,...)
%                      ,set(variables)
%                      ,list(goal)
%                      ,vardict
%                      ,set(variables)
%                      )
%------------------------------------------------------------------------------%

ast_head_arg_matches_([],[],VarDict,GroundVars,[],VarDict,GroundVars).
ast_head_arg_matches_([silent(Arg-Var)| Rest],[Mode|Modes],VarDict,GroundVars,GoalList,NVarDict,NGroundVars) :- !,
	( Mode == (+) ->
		ast_term_variables(Arg,GroundVars0,GroundVars),
		ast_head_arg_matches_(Rest,Modes,VarDict,GroundVars0,GoalList,NVarDict,NGroundVars)
	;
		ast_head_arg_matches_(Rest,Modes,VarDict,GroundVars,GoalList,NVarDict,NGroundVars)
	).
ast_head_arg_matches_([Arg-Var| Rest],[Mode|Modes],VarDict,GroundVars,GoalList,NVarDict,NGroundVars) :-
	( Arg = var(VarId,_) ->
		( get_assoc(VarId,VarDict,OtherVar) ->
			( Mode = (+) ->
				( tree_set_memberchk(VarId,GroundVars) ->
					GoalList = [Var = OtherVar | RestGoalList],
					GroundVars1 = GroundVars
				;
					GoalList = [Var == OtherVar | RestGoalList],
					tree_set_add(GroundVars,VarId,GroundVars1)
				)
		        ;
				GoalList = [Var == OtherVar | RestGoalList],
				GroundVars1 = GroundVars
		        ),
			VarDict1 = VarDict
		;
			put_assoc(VarId,VarDict,Var,VarDict1),
			GoalList = RestGoalList,
			( Mode = (+) ->

				tree_set_add(GroundVars,VarId,GroundVars1)
			;
				GroundVars1 = GroundVars
			)
		),
		Pairs = Rest,
		RestModes = Modes
	; ground(Arg), Arg = '$chr_identifier_match'(ActualArg,IndexType) -> % TODO
	    identifier_label_atom(IndexType,Var,ActualArg,Goal),
	    GoalList = [Goal|RestGoalList],
	    VarDict = VarDict1,
	    GroundVars1 = GroundVars,
	    Pairs = Rest,
	    RestModes = Modes
	; Arg = atomic(Atom) ->
	    ( Mode = (+) ->
	            GoalList = [ Var = Atom | RestGoalList]
	    ;
	            GoalList = [ Var == Atom | RestGoalList]
	    ),
	    VarDict = VarDict1,
	    GroundVars1 = GroundVars,
	    Pairs = Rest,
	    RestModes = Modes
	; Mode == (+), ast_is_ground(GroundVars,Arg)  ->
	    ast_instantiate(VarDict,Arg,ArgInst),
	    GoalList = [ Var = ArgInst | RestGoalList],
	    VarDict = VarDict1,
	    GroundVars1 = GroundVars,
	    Pairs = Rest,
	    RestModes = Modes
	; Mode == (?), ast_is_ground(GroundVars,Arg)  ->
	    ast_instantiate(VarDict,Arg,ArgInst),
	    GoalList = [ Var == ArgInst | RestGoalList],
	    VarDict = VarDict1,
	    GroundVars1 = GroundVars,
	    Pairs = Rest,
	    RestModes = Modes
	;   Arg = compound(Functor,Arity,Arguments,_),
	    functor(Term,Functor,Arity),
	    Term =.. [_|Vars],
	    ( Mode = (+) ->
		GoalList = [ Var = Term | RestGoalList ]
	    ;
		GoalList = [ nonvar(Var), Var = Term | RestGoalList ]
	    ),
	    pairup(Arguments,Vars,NewPairs),
	    append(NewPairs,Rest,Pairs),
	    replicate(N,Mode,NewModes),
	    append(NewModes,Modes,RestModes),
	    VarDict1 = VarDict,
	    GroundVars1 = GroundVars
	),
	ast_head_arg_matches_(Pairs,RestModes,VarDict1,GroundVars1,RestGoalList,NVarDict,NGroundVars).