191 lines
5.8 KiB
Prolog
191 lines
5.8 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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:- op(1150, fx, attribute).
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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_predicate(existing_attribute/3,logical).
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:- dynamic_predicate(modules_with_attributes/1,logical).
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modules_with_attributes([]).
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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, Gs) :- !,
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expand_get_attributes(AccessSpec,Mod,Var,[],GL),
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convert_to_goals(GL,Gs).
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user:goal_expansion(put_atts(Var,AccessSpec), Mod, Gs) :- !,
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expand_put_attributes(AccessSpec,Mod,Var,[],GL),
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convert_to_goals(GL,Gs).
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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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inc_n_of_atts(Key),
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functor(S,Na,Ar),
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store_new_module(Mod),
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assertz(existing_attribute(S,Mod,Key)).
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store_new_module(Mod) :-
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existing_attribute(_,Mod,_), !.
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store_new_module(Mod) :-
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retract(modules_with_attributes(Mods)),
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assertz(modules_with_attributes([Mod|Mods])).
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expand_get_attributes(V,Mod,Var,GL0,GL) :- var(V), !,
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GL = [attributes:get_atts_at_run_time(Var,V,Mod)|GL0].
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expand_get_attributes([],_,_,LG,LG) :- !.
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expand_get_attributes([Att|Atts],Mod,Var,L0,LF) :- !,
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expand_get_attributes(Att,Mod,Var,L0,L1),
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expand_get_attributes(Atts,Mod,Var,L1,LF).
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expand_get_attributes(+Att,Mod,Var,L0,LF) :- !,
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expand_get_attributes(Att,Mod,Var,L0,LF).
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expand_get_attributes(-Att,Mod,Var,L0,[attributes:free_att(Var,Key)|L0]) :- !,
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existing_attribute(Att,Mod,Key).
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expand_get_attributes(Att,Mod,Var,L0,[attributes:get_att(Var,Key,Att)|L0]) :-
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% searching for an attribute
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existing_attribute(Att,Mod,Key).
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get_atts_at_run_time(Var,Atts,Module) :-
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var(Atts), !,
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get_all_atts(Var,LAtts),
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fetch_interesting_attributes(LAtts, Module, Atts).
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get_atts_at_run_time(Var,Atts,Module) :-
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expand_get_attributes(Atts,Module,Var,[],GL),
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convert_to_goals(GL,Gs),
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call(Gs).
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fetch_interesting_attributes([], _, []).
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fetch_interesting_attributes([[I|Att]|LAtts], Module, Atts) :-
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fetch_interesting_attribute(Att, Module, I, Atts, AttsI),
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fetch_interesting_attributes(LAtts, Module, AttsI).
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%
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% only output attributes if they are for the current module.
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%
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fetch_interesting_attribute(Att, Module, Key, [Att|Atts], Atts) :-
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existing_attribute(Att, Module, Key), !.
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fetch_interesting_attribute(_, _, _, Atts, Atts).
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expand_put_attributes(V,Mod,Var,G0,GF) :- var(V), !,
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GF = [attributes:put_atts_at_run_time(Var,V,Mod)|G0].
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expand_put_attributes([],_,_,G,G) :- !.
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expand_put_attributes([Att|Atts],Mod,Var,G0,GF) :- !,
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expand_put_attributes(Att,Mod,Var,G0,GI),
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expand_put_attributes(Atts,Mod,Var,GI,GF).
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expand_put_attributes(+Att,Mod,Var,G0,GF) :- !,
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expand_put_attributes(Att,Mod,Var,G0,GF).
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expand_put_attributes(-Att,Mod,Var,G0,[attributes:rm_att(Var,Key)|G0]) :- !,
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existing_attribute(Att,Mod,Key).
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expand_put_attributes(Att,Mod,Var,G0,[attributes:put_att(Var,Key,Att)|G0]) :-
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% searching for an attribute
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existing_attribute(Att,Mod,Key).
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put_atts_at_run_time(Var,Atts,_) :-
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var(Atts), !,
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throw(error(instantiation_error,put_atts(Var,Atts))).
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put_atts_at_run_time(Var,Atts,Module) :-
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expand_put_attributes(Atts,Module,Var,[],GL),
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convert_to_goals(GL,Gs),
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call(Gs).
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woken_att_do(AttVar, Binding) :-
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modules_with_attributes(Mods),
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do_verify_attributes(Mods, AttVar, Binding, Goals),
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bind_attvar(AttVar),
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lcall(Goals).
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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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existing_attribute(_,Mod,Key),
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get_att(AttVar,Key,_),
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current_predicate(verify_attributes, Mod:verify_attributes(_,_,_)), !,
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do_verify_attributes(Mods, AttVar, Binding, Goals),
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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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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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convert_att_var(V, Gs) :-
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modules_with_attributes(LMods),
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fetch_att_goals(LMods,V,Gs0), !,
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simplify_trues(Gs0, Gs).
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convert_att_var(_, true).
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fetch_att_goals([Mod], Att, G1) :-
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call_module_attributes(Mod, Att, G1), !.
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fetch_att_goals([_], _, true) :- !.
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fetch_att_goals([Mod|LMods], Att, (G1,LGoal)) :-
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call_module_attributes(Mod, Att, G1), !,
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fetch_att_goals(LMods, Att, LGoal).
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fetch_att_goals([_|LMods], Att, LGoal) :-
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fetch_att_goals(LMods, Att, LGoal).
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%
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% if there is an active attribute for this module call attribute_goal.
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%
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call_module_attributes(Mod, AttV, G1) :-
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existing_attribute(_,Mod,Key),
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get_att(AttV,Key,_), !,
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current_predicate(attribute_goal, Mod:attribute_goal(AttV,G1)),
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Mod:attribute_goal(AttV, G1).
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simplify_trues((A,B), NG) :- !,
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simplify_trues(A, NA),
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simplify_trues(B, NB),
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simplify_true(NA, NB, NG).
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simplify_trues(G, G).
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simplify_true(true, G, G) :- !.
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simplify_true(G, true, G) :- !.
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simplify_true(A, B, (A,B)).
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convert_to_goals([G],G) :- !.
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convert_to_goals([A|G],(A,Gs)) :-
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convert_to_goals(G,Gs).
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