%%% -*- Mode: Prolog; -*-

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%  $Date: 2010-11-03 19:13:53 +0100 (Wed, 03 Nov 2010) $
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% nested tries handling
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

:- module(nestedtries, [nested_trie_to_depth_breadth_trie/4]).

:- use_module(library(ordsets), [list_to_ord_set/2, ord_subset/2]). % this two might be better to do a custom fast implementation
:- use_module(library(lists), [memberchk/2, delete/3]).
:- use_module(library(tries), [trie_to_depth_breadth_trie/6, trie_get_depth_breadth_reduction_entry/1, trie_dup/2, trie_close/1, trie_open/1, trie_replace_nested_trie/3, trie_remove_entry/1, trie_get_entry/2, trie_put_entry/3, trie_traverse/2]).

:- use_module(flags, [problog_define_flag/5, problog_flag/2]).

:- style_check(all).
:- yap_flag(unknown,error).

:- initialization((
%   problog_define_flag(subset_check,    problog_flag_validate_boolean, 'perform subset check in nested tries', true, nested_tries),
  problog_define_flag(loop_refine_ancs, problog_flag_validate_boolean, 'refine ancestors if no loop exists', true, nested_tries)
%   problog_define_flag(trie_preprocess, problog_flag_validate_boolean, 'perform a preprocess step to nested tries', false, nested_tries),
%   problog_define_flag(refine_anclst,   problog_flag_validate_boolean, 'refine the ancestor list with their childs', false, nested_tries),
%   problog_define_flag(anclst_represent,problog_flag_validate_in_list([list, integer]), 'represent the ancestor list', list, nested_tries)
)).


trie_replace_entry(_Trie, Entry, _E, false):-
  !, trie_remove_entry(Entry).
trie_replace_entry(Trie, Entry, E, true):-
  !, trie_get_entry(Entry, Proof),
  delete(Proof, E, NewProof),
  (NewProof == [] ->
    trie_delete(Trie),
    trie_put_entry(Trie, [true], _)
  ;
    trie_remove_entry(Entry),
    trie_put_entry(Trie, NewProof, _)
  ).
trie_replace_entry(Trie, _Entry, t(ID), R):-
  trie_replace_nested_trie(Trie, ID, R).

trie_delete(Trie):-
  trie_traverse(Trie, R),
  trie_remove_entry(R),
  fail.
trie_delete(_Trie).

is_state(Variable):-
  Variable == true, !.
is_state(Variable):-
  Variable == false.
is_state(Variable):-
  nonvar(Variable),
  Variable = not(NestedVariable),
  is_state(NestedVariable).

is_trie(Trie, ID):-
  nonvar(Trie),
  Trie = t(ID), !.
is_trie(Trie, ID):-
  nonvar(Trie),
  Trie = not(NestedTrie),
  is_trie(NestedTrie, ID).

is_label(Label, ID):-
  atom(Label), !,
  atomic_concat('L', ID, Label).
is_label(Label, ID):-
  nonvar(Label),
  Label = not(NestedLabel),
  is_label(NestedLabel, ID).

% Ancestor related stuff

initialise_ancestors(0):-
  problog_flag(anclst_represent, integer).
initialise_ancestors([]):-
  problog_flag(anclst_represent, list).

add_to_ancestors(ID, Ancestors, NewAncestors):-
  integer(Ancestors), !,
  NewAncestors is (1 << (ID - 1)) \/ Ancestors.
add_to_ancestors(ID, Ancestors, NewAncestors):-
  is_list(Ancestors),
  list_to_ord_set([ID|Ancestors], NewAncestors).

ancestor_subset_check(SubAncestors, Ancestors):-
  integer(SubAncestors), !,
  SubAncestors is Ancestors /\ SubAncestors.
ancestor_subset_check(SubAncestors, Ancestors):-
  is_list(SubAncestors),
  ord_subset(SubAncestors, Ancestors).

ancestor_loop_refine(Loop, Ancestors, 0):-
  var(Loop), integer(Ancestors), !.
ancestor_loop_refine(Loop, Ancestors, []):-
  var(Loop), is_list(Ancestors), !.
ancestor_loop_refine(true, Ancestors, Ancestors).

% Cycle check related stuff
% missing synonym check

cycle_check(ID, Ancestors):-
  integer(Ancestors), !,
  Bit is 1 << (ID - 1),
  Bit is Bit /\ Ancestors.
cycle_check(ID, Ancestors):-
  is_list(Ancestors),
  memberchk(ID, Ancestors).

preprocess(Index, DepthBreadthTrie, OptimizationLevel, StartCount, FinalEndCount):-
  problog:problog_chktabled(Index, Trie), !,
  trie_dup(Trie, CopyTrie),
  initialise_ancestors(Ancestors),
  make_nested_trie_base_cases(CopyTrie, t(Index), DepthBreadthTrie, OptimizationLevel, StartCount, EndCount, Ancestors),
  trie_close(CopyTrie),
  Next is Index + 1,
  preprocess(Next, DepthBreadthTrie, OptimizationLevel, EndCount, FinalEndCount).
preprocess(_, _, _, FinalEndCount, FinalEndCount).

make_nested_trie_base_cases(Trie, t(ID), DepthBreadthTrie, OptimizationLevel, StartCount, FinalEndCount, Ancestors):-
  trie_to_depth_breadth_trie(Trie, DepthBreadthTrie, Label, OptimizationLevel, StartCount, EndCount),
  (is_trie(Label, SID) ->
    trie_get_depth_breadth_reduction_entry(NestedEntry),
    trie_replace_entry(Trie, NestedEntry, Label, false),
    add_to_ancestors(SID, Ancestors, NewAncestors),
    make_nested_trie_base_cases(Trie, t(ID), DepthBreadthTrie, OptimizationLevel, EndCount, FinalEndCount, NewAncestors)
  ;
    FinalEndCount = EndCount,
    get_set_trie(ID, Label, Ancestors)
  ).

nested_trie_to_depth_breadth_trie(Trie, DepthBreadthTrie, FinalLabel, OptimizationLevel):-
  integer(OptimizationLevel),
  trie_open(DepthBreadthTrie),
  (problog_flag(trie_preprocess, true) ->
    preprocess(1, DepthBreadthTrie, OptimizationLevel, 0, StartCount)
  ;
    StartCount = 0
  ),
  initialise_ancestors(Ancestors),
%   initialise_ancestors(Childs),
  (problog_flag(loop_refine_ancs, true) ->
    trie_2_dbtrie_init(Trie, DepthBreadthTrie, OptimizationLevel, StartCount, _, Ancestors, FinalLabel, _)
  ;
    trie_2_dbtrie_init(Trie, DepthBreadthTrie, OptimizationLevel, StartCount, _, Ancestors, FinalLabel, true)
  ),
  eraseall(problog_trie_table).

trie_2_dbtrie_init(ID, DepthBreadthTrie, OptimizationLevel, StartCount, EndCount, Ancestors, Label, ContainLoop):-
  get_trie_pointer(ID, Trie),
  trie_dup(Trie, CopyTrie),
  trie_2_dbtrie_intern(CopyTrie, DepthBreadthTrie, OptimizationLevel, StartCount, EndCount, Ancestors, Label, ContainLoop),
  trie_close(CopyTrie).

trie_2_dbtrie_intern(Trie, DepthBreadthTrie, OptimizationLevel, StartCount, FinalEndCount, Ancestors, TrieLabel, ContainLoop):-
  trie_to_depth_breadth_trie(Trie, DepthBreadthTrie, Label, OptimizationLevel, StartCount, EndCount),
  (is_trie(Label, ID) ->             % Label might have issues with negation
    trie_get_depth_breadth_reduction_entry(NestedEntry),
    % check if Trie introduces a loop
    (cycle_check(ID, Ancestors) ->
      ContainLoop = true,
      NewLabel = false,
      NewEndCount = EndCount
    ;
      % check if Trie is resolved and extract it
      (get_set_trie(ID, NewLabel, Ancestors) ->
        NewEndCount = EndCount
      ;
        % calculate the nested trie
        add_to_ancestors(ID, Ancestors, NewAncestors), % to be able to support 2 representations
        trie_2_dbtrie_init(ID, DepthBreadthTrie, OptimizationLevel, EndCount, NewEndCount, NewAncestors, NewLabel, NewContainLoop),
        ancestor_loop_refine(NewContainLoop, Ancestors, RefinedAncestors),
        get_set_trie(ID, NewLabel, RefinedAncestors),
        ContainLoop = NewContainLoop
      )
    ),
    trie_replace_entry(Trie, NestedEntry, t(ID), NewLabel), % should be careful to verify that it works also with not(t(ID))
    trie_2_dbtrie_intern(Trie, DepthBreadthTrie, OptimizationLevel, NewEndCount, FinalEndCount, Ancestors, TrieLabel, ContainLoop)
  ;
    % else we can terminate and return
    FinalEndCount = EndCount,
    TrieLabel = Label
  ).

% predicate to check/remember resolved tries
% no refiment of ancestor list included

get_trie_pointer(ID, Trie):-
  problog:problog_chktabled(ID, Trie), !.
get_trie_pointer(Trie, Trie).

get_set_trie(Trie, Label, Ancestors):-
  recorded(problog_trie_table, store(Trie, StoredAncestors, Label), _),
  (problog_flag(subset_check, true) ->
    ancestor_subset_check(StoredAncestors, Ancestors)
  ;
    StoredAncestors == Ancestors
  ), !.
get_set_trie(Trie, Label, Ancestors):-
  ground(Label),
  recordz(problog_trie_table, store(Trie, Ancestors, Label), _).


% chk_negated([H|T], ID):-
%   simplify(H, not(t(ID))), !.
% chk_negated([_|T], ID):-
%   chk_negated(T, ID).


/*
chk_negated([], ID, ID).
chk_negated([H|T], ID, not(ID)):-
  simplify(H, not(t(ID))), !.
chk_negated([H|T], ID, ID):-
  simplify(H, t(ID)), !.
chk_negated([_|T], ID, FID):-
  chk_negated(T, ID, FID).*/