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