374 lines
9.6 KiB
Prolog
374 lines
9.6 KiB
Prolog
%
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% A compiler for Meld programs
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% can understand aggregates.
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%
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:- module(meld_compiler,
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[
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mcompile/1,
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input_graph/1,
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run/1
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]).
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:- use_module(meldi,
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[
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push/1,
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first/2,
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min/3,
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max/3,
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sum/3
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]).
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:- use_module(library(meld)).
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:- use_module(library(terms), [
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variable_in_term/2
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]).
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:- use_module(library(ordsets), [
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ord_subset/2,
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ord_union/3
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]).
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:- dynamic meld_constants:const/2.
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mcompile(Program) :-
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open(Program, read, P),
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init_mcompile(Program),
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repeat,
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read_term(P, Term, [variable_names(Vars), module(meld_compiler)]),
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(
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Term == end_of_file
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->
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!,
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close(P)
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;
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mcompile(Term, Program, Vars),
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fail
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).
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init_mcompile(Program) :-
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retractall(type(_, _, Program, _)).
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mcompile(type(T), Program, Vars) :-
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ground_term(T, Vars),
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type_declaration(T, Program), !.
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mcompile(const(T=V), _Program, Vars) :-
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ground_term(T, Vars),
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const_declaration(T, V), !.
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mcompile((Head :- Body), _, _Vars) :-
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rule(Head, Body).
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type_declaration(extensional(T), Program) :- !,
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functor(T, Na, Arity),
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functor(NT, Na, Arity),
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assert(meld_topdown:extensional(NT, Na, Arity)),
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type_declaration(T, Program).
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type_declaration(logical_neighbor(T), Program) :- !,
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type_declaration(T, Program).
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type_declaration(persistent(T), Program) :- !,
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type_declaration(T, Program).
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type_declaration(extern(T), Program) :- !,
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type_declaration(T, Program).
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type_declaration(T, _) :-
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functor(T, N, A),
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dynamic(meld_program:N/A),
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fail.
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type_declaration(T, Program) :-
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T =.. [P|Args],
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check_aggregate(Args, 1, NewArgs, Aggregation, Arg),
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!,
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NT =.. [P|NewArgs],
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assert_type(NT, Program, aggregation(Aggregation, Arg)).
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type_declaration(T, Program) :-
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assert_type(T, Program, horn).
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assert_type(NT, Program, Agg) :-
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functor(NT, Na, Ar),
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functor(Spec, Na, Ar),
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assert(type(Spec, NT, Program, Agg)).
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const_declaration(C,V) :- !,
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( atom(C) -> true ; throw(type_error(atom,C),const(C=V))),
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( number(V) -> true ; throw(type_error(number,V),const(C=V))),
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assert(meld_constants:const(C, V)).
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check_aggregate([first(Type)|Args], I, [Type|Args], first, I) :- !.
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check_aggregate([max(Type)|Args], I, [Type|Args], max, I) :- !.
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check_aggregate([min(Type)|Args], I, [Type|Args], min, I) :- !.
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check_aggregate([sum(Type)|Args], I, [Type|Args], sum, I) :- !.
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check_aggregate([Type|Args], I, [Type|NewArgs], Agg, Arg) :-
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atom(Type),
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I1 is I+1,
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check_aggregate(Args, I1, NewArgs, Agg, Arg).
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ground_term(_, []).
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%
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% Rule compiler
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%
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rule(Head, Body) :-
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bodytolist(Body, L0, []),
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builtins(L0, L, R),
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builtins([Head], RLH, []),
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join(RLH, NHead, R, []),
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compile_goals(L, [], NHead).
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builtins([]) --> [].
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builtins(G.Gs) -->
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builtin(G),
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builtins(Gs).
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builtin(Res = Op) --> !,
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process_constants(Op, Res).
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builtin(Goal) -->
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process_constants(Goal, NGoal),
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[ NGoal ].
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process_constants(G, G) -->
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{ var(G) }, !.
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process_constants(C, V) -->
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{ meld_constants:const(C,V) }, !.
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process_constants(G, G) -->
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{ atomic(G) }, !.
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process_constants(to_float(Arg1), NArg1) --> !,
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process_constants(Arg1, NArg1).
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process_constants(A, NA) -->
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{ arithmetic(A, Op, Arg1, Arg2) }, !,
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process_constants(Arg1, NArg1),
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process_constants(Arg2, NArg2),
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{ arithmetic(NExp, Op, NArg1, NArg2) },
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[ NA is NExp ].
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process_constants(A, NA) -->
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{ arithmetic(A, Op, Arg1) }, !,
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process_constants(Arg1, NArg1),
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{ arithmetic(NExp, Op, NArg1) },
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[ NA is NExp ].
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process_constants(G, NG) -->
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{ G =.. [A|Args] },
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process_args(Args, NArgs),
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{ NG =.. [A|NArgs] }.
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process_args([], []) --> [].
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process_args(A.Args, NA.NArgs) -->
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process_constants(A, NA),
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process_args(Args, NArgs).
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join([H0], H0) --> !.
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join([H|T], H0) -->
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[H],
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join(T, H0).
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compile_goals([], _, _).
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compile_goals([Goal|Goals], Gs, Head) :-
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compile_goal(Goal, Goals, Gs, Head),
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compile_goals(Goals, [Goal|Gs], Head).
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compile_goal(BIP, _Goals, _Gs, _Head) :-
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meld_builtin(BIP, _, _), !.
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compile_goal((forall G then Do), Goals, Gs, Head) :- !,
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% make sure quantified variables are not seen outside
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quantified_vars(G,Gs+Goals,NG),
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%
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% just collect the body into a number of goals
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%
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collect_body(Gs, [(forall G then Do)|Goals], BLF, BL1),
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% make a backup copy for deletion
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copy_term(h(Head,BLF,BL1,NG), h(Head,DelBLF,DelBL1,DelNG)),
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% add the operation, usually push
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extra_head(Head, BL1, []),
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% add the delete operation
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extra_delete(Head, DelBL1, []),
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% reorder builtins
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reorder_builtins(NG, BLF, BLF2),
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reorder_builtins(DelNG, DelBLF, DelBLF2),
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% create the body as a conjunction
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listtobody(BLF2, Body),
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listtobody(DelBLF2, DelBody),
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% done
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assert_static(meld_program:(run(NG) :- Body)),
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assert_static(meld_program:(run(delete(DelNG)) :- DelBody)).
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compile_goal(Goal, Goals, Gs, Head) :-
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collect_body(Gs, Goals, BLF, BL1),
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copy_term(h(Head,BLF,BL1,Goal), h(Head,DelBLF,DelBL1,DelGoal)),
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extra_head(Head, BL1, []),
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extra_delete(Head, DelBL1, []),
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% reorder builtins
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reorder_builtins(Goal, BLF, BLF2),
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reorder_builtins(DelGoal, DelBLF, DelBLF2),
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listtobody(BLF2, Body),
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listtobody(DelBLF2, DelBody),
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assert_static(meld_program:(run(Goal) :- Body)),
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assert_static(meld_program:(run(deleted(DelGoal)) :- DelBody)).
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% quantified variables should not leave the scope of the forall.
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quantified_vars(G,Extern,NG) :-
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term_variables(G, TVs),
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copy_term(G+TVs,NG+NTVs),
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bind_external(TVs, NTVs, Extern).
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bind_external([], [], _).
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bind_external(V.TVs, NV.NTVs, Extern) :-
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variable_in_term(Extern, V), !,
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V = NV,
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bind_external(TVs, NTVs, Extern).
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bind_external(_.TVs, _.NTVs, Extern) :-
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bind_external(TVs, NTVs, Extern).
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% a very simple version
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%
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collect_body([], []) --> [].
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collect_body([G|Gs], MGs) -->
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process_goal(G),
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collect_body(Gs, MGs).
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collect_body([], [G|Gs]) -->
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process_goal(G),
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collect_body([], Gs).
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process_goal((forall Goal then Conj)) --> !,
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[(Goal, \+ Conj -> fail ; true)].
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process_goal( G ) -->
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[G].
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extra_head(Head) -->
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{ type(Head, _, _, horn) },
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[push(Head)].
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extra_head(Head) -->
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{ type(Head, _, _, aggregation(first, Arg)),
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freshen(Head, Arg, VHead) },
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[ meld_interpreter:first(VHead, Head)].
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extra_head(Head) -->
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{ type(Head, _, _, aggregation(max, Arg)),
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freshen(Head, Arg, VHead) },
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[ meld_interpreter:max(VHead, Arg, Head)].
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extra_head(Head) -->
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{ type(Head, _, _, aggregation(min, Arg)),
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freshen(Head, Arg, VHead) },
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[ meld_interpreter:min(VHead, Arg, Head)].
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extra_head(Head) -->
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{ type(Head, _, _, aggregation(sum, Arg)),
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freshen(Head, Arg, VHead) },
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[ meld_interpreter:sum(VHead, Arg, Head)].
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extra_delete(Head) -->
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{ type(Head, _, _, horn) },
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[meld_interpreter:deleted(Head)].
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extra_delete(Head) -->
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{ type(Head, _, _, aggregation(first, Arg)),
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freshen(Head, Arg, VHead) },
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[ meld_interpreter:delete_from_first(VHead, Head)].
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extra_delete(Head) -->
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{ type(Head, _, _, aggregation(max, Arg)),
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freshen(Head, Arg, VHead) },
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[ meld_interpreter:delete_from_max(VHead, Arg, Head)].
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extra_delete(Head) -->
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{ type(Head, _, _, aggregation(min, Arg)),
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freshen(Head, Arg, VHead) },
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[ meld_interpreter:delete_from_min(VHead, Arg, Head)].
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extra_delete(Head) -->
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{ type(Head, _, _, aggregation(sum, Arg)),
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freshen(Head, Arg, VHead) },
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[ meld_interpreter:delete_from_sum(VHead, Arg, Head)].
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freshen(Head, Arg, VHead) :-
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Head =.. [N|Args],
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freshen_arg(Arg, Args, VArgs),
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VHead =.. [N|VArgs].
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freshen_arg(1, [_|Args], [_|Args]) :- !.
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freshen_arg(N, A.Args, A.VArgs) :-
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N1 is N-1,
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freshen_arg(N1, Args, VArgs).
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input_graph(Program) :-
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open(Program, read, P),
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repeat,
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read_term(P, Term, [variable_names(_Vars), module(meld_compiler)]),
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(
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Term == end_of_file
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->
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!,
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close(P)
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;
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add_graph_fact(Term),
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fail
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).
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add_graph_fact(Term) :-
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push(Term).
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bodytolist((G1,G2)) -->
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!,
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bodytolist(G1),
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bodytolist(G2).
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bodytolist(G) -->
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[G].
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listtobody([G], G) :- !.
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listtobody([G|GL], (G,Gs)) :-
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listtobody(GL, Gs).
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reorder_builtins(Head, BLF, BLF2) :-
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term_variables(Head, Vs0),
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sort(Vs0, Vs),
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reorder_term(BLF, Vs, [], BLF2).
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% 4 arguments
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% list of input goals
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% queue of built-ins waiting for execution
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% list of current variables
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% output variables
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%
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reorder_term([], _, [], []).
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reorder_term(G.Gs, Vs0, Queue, NGs) :-
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meld_builtin(G, Is, Os), !,
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term_variables(Is, InpVs0),
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sort(InpVs0, InpVs),
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continue_reorder_term(Gs, G, InpVs, Vs0, Queue, Os, NGs).
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reorder_term(G.Gs, Vs0, Queue, G.NGs) :-
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term_variables(G, GVs0),
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sort(GVs0, GVs),
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ord_union(GVs, Vs0, Vs),
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wake_queue(Queue, NewQueue, Vs, Vs0, NewQueue, FVs, NGs, NGs0),
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reorder_term(Gs, FVs, NewQueue, NGs0).
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continue_reorder_term(Gs, G, InpVs, Vs0, Queue, Os, G.NGs) :-
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ord_subset(InpVs, Vs0), !,
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term_variables(Os, OutVs0),
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sort(OutVs0, OutVs),
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ord_union(OutVs, Vs0, Vs),
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wake_queue(Queue, NewQueue, Vs, Vs0, NewQueue, FVs, NGs, NGs0),
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reorder_term(Gs, FVs, NewQueue, NGs0).
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continue_reorder_term(Gs, G, InpVs, Vs0, Queue, Os, NGs) :-
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term_variables(Os, OutVs0),
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sort(OutVs0, OutVs),
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reorder_term(Gs, Vs0, q(InpVs, OutVs, G).Queue, NGs).
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wake_queue([], _, Vs, _, [], Vs) --> [].
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wake_queue(Q.Queue, _, Vs, Vs0, Q.Queue, Vs) --> { Vs == Vs0 }, !.
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wake_queue(q(InpVs,OutVs,G).Queue, NewQueue, Vs, Vs0, Queue, FVs) -->
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{ ord_subset(InpVs, Vs) }, !,
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[G],
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{ ord_union(OutVs, Vs, NVs) },
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% restart from beginning
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wake_queue(NewQueue, NewNewQueue, NVs, Vs0, NewNewQueue, FVs).
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wake_queue(Q.Queue, NewQueue, NVs, Vs0, Q.NQueue, FVs) -->
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wake_queue(Queue, NewQueue, NVs, Vs0, NQueue, FVs).
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meld_builtin(O is I, I, O).
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meld_builtin(I1 =< I2, I1-I2, []).
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meld_builtin(I1 >= I2, I1-I2, []).
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meld_builtin(I1 =:= I2, I1-I2, []).
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arithmetic( A+B, (+), A, B).
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arithmetic( A-B, (-), A, B).
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arithmetic( A*B, (*), A, B).
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arithmetic( A/B, (/), A, B).
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arithmetic( sin(A), sin, A).
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arithmetic( cos(A), cos, A).
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arithmetic( tan(A), tan, A).
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