347 lines
8.8 KiB
Prolog
347 lines
8.8 KiB
Prolog
/*************************************************************************
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* *
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* YAP Prolog *
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* *
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* Yap Prolog was developed at NCCUP - Universidade do Porto *
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* *
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* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 *
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* *
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**************************************************************************
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* *
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* File: atts.yap *
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* Last rev: 8/2/88 *
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* mods: *
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* comments: attribute support for Prolog *
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* *
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*************************************************************************/
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:- module('$attributes', [
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delayed_goals/4
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]).
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:- use_system_module( '$_boot', ['$undefp'/1]).
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:- use_system_module( '$_errors', ['$do_error'/2]).
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:- use_system_module( '$coroutining', [attr_unify_hook/2]).
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:- use_system_module( attributes, [all_attvars/1,
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attributed_module/3,
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bind_attvar/1,
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del_all_atts/1,
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del_all_module_atts/2,
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get_all_swi_atts/2,
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get_module_atts/2,
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modules_with_attributes/1,
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put_att_term/2,
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put_module_atts/2,
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unbind_attvar/1,
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woken_att_do/4]).
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:- dynamic attributes:attributed_module/3, attributes:modules_with_attributes/1.
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prolog:get_attr(Var, Mod, Att) :-
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functor(AttTerm, Mod, 2),
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arg(2, AttTerm, Att),
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attributes:get_module_atts(Var, AttTerm).
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prolog:put_attr(Var, Mod, Att) :-
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functor(AttTerm, Mod, 2),
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arg(2, AttTerm, Att),
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attributes:put_module_atts(Var, AttTerm).
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prolog:del_attr(Var, Mod) :-
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functor(AttTerm, Mod, 2),
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attributes:del_all_module_atts(Var, AttTerm).
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prolog:del_attrs(Var) :-
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attributes:del_all_atts(Var).
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prolog:get_attrs(AttVar, SWIAtts) :-
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attributes:get_all_swi_atts(AttVar,SWIAtts).
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prolog:put_attrs(_, []).
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prolog:put_attrs(V, Atts) :-
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cvt_to_swi_atts(Atts, YapAtts),
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attributes:put_att_term(V, YapAtts).
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cvt_to_swi_atts([], _).
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cvt_to_swi_atts(att(Mod,Attribute,Atts), ModAttribute) :-
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ModAttribute =.. [Mod, YapAtts, Attribute],
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cvt_to_swi_atts(Atts, YapAtts).
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%
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% wake_up_goal is called by the system whenever a suspended goal
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% resumes.
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%
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/* The first case may happen if this variable was used for dif.
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In this case, we need a way to keep the original
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suspended goal around
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*/
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%'$wake_up_goal'([Module1|Continuation],G) :-
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% '$write'(4,vsc_woke:G+[Module1|Continuation]:'
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%'), fail.
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prolog:'$wake_up_goal'([Module1|Continuation], LG) :-
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% writeln( [Module1|Continuation]:LG),
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execute_woken_system_goals(LG),
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do_continuation(Continuation, Module1).
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%
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% in the first two cases restore register immediately and proceed
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% to continuation. In the last case take care with modules, but do
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% not act as if a meta-call.
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%
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%
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do_continuation('$cut_by'(X), _) :- !,
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'$$cut_by'(X).
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do_continuation('$restore_regs'(X), _) :- !,
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% yap_flag(gc_trace,verbose),
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% garbage_collect,
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'$restore_regs'(X).
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do_continuation('$restore_regs'(X,Y), _) :- !,
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% yap_flag(gc_trace,verbose),
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% garbage_collect,
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'$restore_regs'(X,Y).
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do_continuation(Continuation, Module1) :-
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execute_continuation(Continuation,Module1).
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execute_continuation(Continuation, Module1) :-
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'$undefined'(Continuation, Module1), !,
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'$undefp'([Module1|Continuation]).
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execute_continuation(Continuation, Mod) :-
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% do not do meta-expansion nor any fancy stuff.
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'$execute0'(Continuation, Mod).
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execute_woken_system_goals([]).
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execute_woken_system_goals(['$att_do'(V,New)|LG]) :-
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execute_woken_system_goals(LG),
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call_atts(V,New).
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%
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% what to do when an attribute gets bound
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%
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call_atts(V,_) :-
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nonvar(V), !.
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call_atts(V,_) :-
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'$att_bound'(V), !.
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call_atts(V,New) :-
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attributes:get_all_swi_atts(V,SWIAtts),
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(
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'$undefined'(woken_att_do(V, New, LGoals, DoNotBind), attributes)
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->
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LGoals = [],
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DoNotBind = false
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;
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attributes:woken_att_do(V, New, LGoals, DoNotBind)
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),
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( DoNotBind == true
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->
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attributes:unbind_attvar(V)
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;
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attributes:bind_attvar(V)
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),
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do_hook_attributes(SWIAtts, New),
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lcall(LGoals).
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do_hook_attributes([], _).
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do_hook_attributes(att(Mod,Att,Atts), Binding) :-
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('$undefined'(attr_unify_hook(Att,Binding), Mod)
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->
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true
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;
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Mod:attr_unify_hook(Att, Binding)
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),
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do_hook_attributes(Atts, Binding).
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lcall([]).
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lcall([Mod:Gls|Goals]) :-
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lcall2(Gls,Mod),
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lcall(Goals).
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lcall2([], _).
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lcall2([Goal|Goals], Mod) :-
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call(Mod:Goal),
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lcall2(Goals, Mod).
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prolog:call_residue_vars(Goal,Residue) :-
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attributes:all_attvars(Vs0),
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call(Goal),
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attributes:all_attvars(Vs),
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% this should not be actually strictly necessary right now.
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% but it makes it a safe bet.
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sort(Vs, Vss),
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sort(Vs0, Vs0s),
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'$ord_remove'(Vss, Vs0s, Residue).
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'$ord_remove'([], _, []).
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'$ord_remove'([V|Vs], [], [V|Vs]).
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'$ord_remove'([V1|Vss], [V2|Vs0s], Residue) :-
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( V1 == V2 ->
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'$ord_remove'(Vss, Vs0s, Residue)
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;
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V1 @< V2 ->
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Residue = [V1|ResidueF],
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'$ord_remove'(Vss, [V2|Vs0s], ResidueF)
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;
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'$ord_remove'([V1|Vss], Vs0s, Residue)
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).
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%% from SWI
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%% copy_term(+Term, -Copy, -Gs) is det.
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%
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% Creates a regular term Copy as a copy of Term (without any
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% attributes), and a list Gs of goals that when executed reinstate
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% all attributes onto Copy. The nonterminal attribute_goals//1, as
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% defined in the modules the attributes stem from, is used to
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% convert attributes to lists of goals.
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prolog:copy_term(Term, Copy, Gs) :-
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term_attvars(Term, Vs),
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( Vs == []
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-> Gs = [],
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copy_term(Term, Copy)
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; findall(Term-Gs,
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'$attributes':residuals_and_delete_attributes(Vs, Gs, Term),
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[Copy-Gs])
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).
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residuals_and_delete_attributes(Vs, Gs, Term) :-
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attvars_residuals(Vs, Gs, []),
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delete_attributes(Term).
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attvars_residuals([]) --> [].
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attvars_residuals([V|Vs]) -->
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( { get_attrs(V, As) }
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-> attvar_residuals(As, V)
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; []
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),
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attvars_residuals(Vs).
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attvar_residuals([], _) --> [].
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attvar_residuals(att(Module,Value,As), V) -->
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( { nonvar(V) }
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-> % a previous projection predicate could have instantiated
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% this variable, for example, to avoid redundant goals
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[]
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; { attributes:attributed_module(Module, _, _) } ->
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% SICStus like run, put attributes back first
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{ Value =.. [Name,_|Vs],
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NValue =.. [Name,_|Vs],
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attributes:put_module_atts(V,NValue)
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},
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attvar_residuals(As, V),
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( { '$undefined'(attribute_goal(V, Goal), Module) }
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->
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[]
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;
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{ call(Module:attribute_goal(V, Goal)) },
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dot_list(Goal)
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)
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; ( { current_predicate(Module:attribute_goals/3) }
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-> { call(Module:attribute_goals(V, Goals, [])) },
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list(Goals)
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; { current_predicate(Module:attribute_goal/2) }
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-> { call(Module:attribute_goal(V, Goal)) },
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dot_list(Goal)
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; [put_attr(V, Module, Value)]
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),
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attvar_residuals(As, V)
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).
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list([]) --> [].
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list([L|Ls]) --> [L], list(Ls).
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dot_list((A,B)) --> !, dot_list(A), dot_list(B).
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dot_list(A) --> [A].
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delete_attributes(Term) :-
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term_attvars(Term, Vs),
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delete_attributes_(Vs).
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delete_attributes_([]).
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delete_attributes_([V|Vs]) :-
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del_attrs(V),
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delete_attributes_(Vs).
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prolog:call_residue(Goal,Residue) :-
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var(Goal), !,
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'$do_error'(instantiation_error,call_residue(Goal,Residue)).
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prolog:call_residue(Module:Goal,Residue) :-
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atom(Module), !,
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call_residue(Goal,Module,Residue).
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prolog:call_residue(Goal,Residue) :-
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'$current_module'(Module),
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call_residue(Goal,Module,Residue).
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call_residue(Goal,Module,Residue) :-
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prolog:call_residue_vars(Module:Goal,NewAttVars),
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(
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attributes:modules_with_attributes([_|_])
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->
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project_attributes(NewAttVars, Module:Goal)
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;
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true
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),
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copy_term(Goal, Goal, Residue).
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delayed_goals(G, Vs, NVs, Gs) :-
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project_delayed_goals(G),
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% term_factorized([G|Vs], [_|NVs], Gs).
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copy_term([G|Vs], [_|NVs], Gs).
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project_delayed_goals(G) :-
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% SICStus compatible step,
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% just try to simplify store by projecting constraints
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% over query variables.
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% called by top_level to find out about delayed goals
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attributes:modules_with_attributes([_|_]), !,
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attributes:all_attvars(LAV),
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LAV = [_|_],
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project_attributes(LAV, G), !.
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project_delayed_goals(_).
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attributed(G, Vs) :-
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term_variables(G, LAV),
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att_vars(LAV, Vs).
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att_vars([], []).
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att_vars([V|LGs], [V|AttVars]) :- attvar(V), !,
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att_vars(LGs, AttVars).
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att_vars([_|LGs], AttVars) :-
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att_vars(LGs, AttVars).
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% make sure we set the suspended goal list to its previous state!
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% make sure we have installed a SICStus like constraint solver.
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project_attributes(AllVs, G) :-
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attributes:modules_with_attributes(LMods),
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LMods = [_|_],
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term_variables(G, InputVs),
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pick_att_vars(InputVs, AttIVs),
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project_module(LMods, AttIVs, AllVs).
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pick_att_vars([],[]).
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pick_att_vars([V|L],[V|NL]) :- attvar(V), !,
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pick_att_vars(L,NL).
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pick_att_vars([_|L],NL) :-
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pick_att_vars(L,NL).
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project_module([], _, _).
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project_module([Mod|LMods], LIV, LAV) :-
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'$pred_exists'(project_attributes(LIV, LAV),Mod),
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call(Mod:project_attributes(LIV, LAV)), !,
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attributes:all_attvars(NLAV),
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project_module(LMods,LIV,NLAV).
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project_module([_|LMods], LIV, LAV) :-
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project_module(LMods,LIV,LAV).
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