189 lines
6.0 KiB
Prolog
189 lines
6.0 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, [op(1150, fx, attribute)]).
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:- use_module(library(lists), [member/2]).
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:- multifile
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user:goal_expansion/3.
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:- multifile
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user:term_expansion/2.
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:- dynamic existing_attribute/4.
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:- dynamic modules_with_attributes/1.
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:- dynamic attributed_module/3.
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modules_with_attributes([]).
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%
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% defining a new attribute is just a question of establishing a
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% Functor, Mod -> INT mappings
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%
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new_attribute(V) :- var(V), !,
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throw(error(instantiation_error,attribute(V))).
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new_attribute((At1,At2)) :-
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new_attribute(At1),
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new_attribute(At2).
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new_attribute(Na/Ar) :-
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source_module(Mod),
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functor(S,Na,Ar),
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existing_attribute(S,Mod,_,_) , !.
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new_attribute(Na/Ar) :-
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source_module(Mod),
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functor(S,Na,Ar),
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store_new_module(Mod,Ar,Position),
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assertz(existing_attribute(S,Mod,Ar,Position)).
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store_new_module(Mod,Ar,ArgPosition) :-
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(
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retract(attributed_module(Mod,Position,_))
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->
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true
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;
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retract(modules_with_attributes(Mods)),
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assert(modules_with_attributes([Mod|Mods])), Position = 2
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),
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ArgPosition is Position+1,
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( Ar == 0 -> NOfAtts is Position+1 ; NOfAtts is Position+Ar),
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functor(AccessTerm,Mod,NOfAtts),
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assertz(attributed_module(Mod,NOfAtts,AccessTerm)).
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:- user_defined_directive(attribute(G), attributes:new_attribute(G)).
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user:goal_expansion(get_atts(Var,AccessSpec), Mod, Goal) :-
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expand_get_attributes(AccessSpec,Mod,Var,Goal).
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user:goal_expansion(put_atts(Var,AccessSpec), Mod, Goal) :-
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expand_put_attributes(AccessSpec, Mod, Var, Goal).
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expand_get_attributes(V,_,_,_) :- var(V), !, fail.
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expand_get_attributes([],_,_,true) :- !.
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expand_get_attributes([-G1],Mod,V,attributes:free_att(V,Mod,Pos)) :-
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existing_attribute(G1,Mod,_,Pos), !.
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expand_get_attributes([+G1],Mod,V,attributes:get_att(V,Mod,Pos,A)) :-
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existing_attribute(G1,Mod,1,Pos), !,
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arg(1,G1,A).
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expand_get_attributes([G1],Mod,V,attributes:get_att(V,Mod,Pos,A)) :-
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existing_attribute(G1,Mod,1,Pos), !,
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arg(1,G1,A).
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expand_get_attributes(Atts,Mod,Var,attributes:get_module_atts(Var,AccessTerm)) :- Atts = [_|_], !,
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attributed_module(Mod,NOfAtts,AccessTerm),
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void_term(Void),
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cvt_atts(Atts,Mod,Void,LAtts),
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sort(LAtts,SortedLAtts),
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free_term(Free),
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build_att_term(1,NOfAtts,SortedLAtts,Free,AccessTerm).
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expand_get_attributes(Att,Mod,Var,Goal) :-
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expand_get_attributes([Att],Mod,Var,Goal).
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build_att_term(NOfAtts,NOfAtts,[],_,_) :- !.
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build_att_term(I0,NOfAtts,[I-Info|SortedLAtts],Void,AccessTerm) :-
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I is I0+1, !,
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copy_att_args(Info,I0,NI,AccessTerm),
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build_att_term(NI,NOfAtts,SortedLAtts,Void,AccessTerm).
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build_att_term(I0,NOfAtts,SortedLAtts,Void,AccessTerm) :-
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I is I0+1,
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arg(I,AccessTerm,Void),
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build_att_term(I,NOfAtts,SortedLAtts,Void,AccessTerm).
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cvt_atts(V,_,_,_) :- var(V), !, fail.
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cvt_atts([],_,_,[]).
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cvt_atts([V|_],_,_,_) :- var(V), !, fail.
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cvt_atts([+Att|Atts],Mod,Void,[Pos-LAtts|Read]) :- !,
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existing_attribute(Att,Mod,_,Pos),
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(atom(Att) -> LAtts = [_] ; Att=..[_|LAtts]),
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cvt_atts(Atts,Mod,Void,Read).
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cvt_atts([-Att|Atts],Mod,Void,[Pos-LVoids|Read]) :- !,
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existing_attribute(Att,Mod,_,Pos),
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(
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atom(Att)
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->
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LVoids = [Void]
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;
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Att =..[_|LAtts],
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void_vars(LAtts,Void,LVoids)
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),
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cvt_atts(Atts,Mod,Void,Read).
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cvt_atts([Att|Atts],Mod,Void,[Pos-LAtts|Read]) :- !,
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existing_attribute(Att,Mod,_,Pos),
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(atom(Att) -> LAtts = [_] ; Att=..[_|LAtts]),
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cvt_atts(Atts,Mod,Void,Read).
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copy_att_args([],I,I,_).
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copy_att_args([V|Info],I,NI,AccessTerm) :-
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I1 is I+1,
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arg(I1,AccessTerm,V),
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copy_att_args(Info,I1,NI,AccessTerm).
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void_vars([],_,[]).
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void_vars([_|LAtts],Void,[Void|LVoids]) :-
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void_vars(LAtts,Void,LVoids).
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expand_put_attributes(V,_,_,_) :- var(V), !, fail.
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expand_put_attributes([-G1],Mod,V,attributes:rm_att(V,Mod,NOfAtts,Pos)) :-
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existing_attribute(G1,Mod,_,Pos), !,
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attributed_module(Mod,NOfAtts,_).
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expand_put_attributes([+G1],Mod,V,attributes:put_att(V,Mod,NOfAtts,Pos,A)) :-
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existing_attribute(G1,Mod,1,Pos), !,
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attributed_module(Mod,NOfAtts,_),
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arg(1,G1,A).
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expand_put_attributes([G1],Mod,V,attributes:put_att(V,Mod,NOfAtts,Pos,A)) :-
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existing_attribute(G1,Mod,1,Pos), !,
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attributed_module(Mod,NOfAtts,_),
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arg(1,G1,A).
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expand_put_attributes(Atts,Mod,Var,attributes:put_module_atts(Var,AccessTerm)) :- Atts = [_|_], !,
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attributed_module(Mod,NOfAtts,AccessTerm),
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void_term(Void),
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cvt_atts(Atts,Mod,Void,LAtts),
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sort(LAtts,SortedLAtts),
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free_term(Free),
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build_att_term(1,NOfAtts,SortedLAtts,Free,AccessTerm).
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expand_put_attributes(Att,Mod,Var,Goal) :-
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expand_put_attributes([Att],Mod,Var,Goal).
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woken_att_do(AttVar, Binding, NGoals, DoNotBind) :-
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modules_with_attributes(AttVar,Mods0),
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modules_with_attributes(Mods),
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find_used(Mods,Mods0,[],ModsI),
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do_verify_attributes(ModsI, AttVar, Binding, Goals),
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process_goals(Goals, NGoals, DoNotBind).
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% dirty trick to be able to unbind a variable that has been constrained.
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process_goals([], [], _).
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process_goals((M:do_not_bind_variable(Gs)).Goals, (M:Gs).NGoals, true) :- !,
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process_goals(Goals, NGoals, _).
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process_goals(G.Goals, G.NGoals, Do) :-
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process_goals(Goals, NGoals, Do).
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find_used([],_,L,L).
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find_used([M|Mods],Mods0,L0,Lf) :-
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member(M,Mods0), !,
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find_used(Mods,Mods0,[M|L0],Lf).
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find_used([_|Mods],Mods0,L0,Lf) :-
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find_used(Mods,Mods0,L0,Lf).
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do_verify_attributes([], _, _, []).
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do_verify_attributes([Mod|Mods], AttVar, Binding, [Mod:Goal|Goals]) :-
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current_predicate(verify_attributes,Mod:verify_attributes(_,_,_)), !,
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Mod:verify_attributes(AttVar, Binding, Goal),
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do_verify_attributes(Mods, AttVar, Binding, Goals).
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do_verify_attributes([_|Mods], AttVar, Binding, Goals) :-
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do_verify_attributes(Mods, AttVar, Binding, Goals).
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