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1a977ea19a
*.nl: Replace all occurrences of `not(Vars, Goal)' with just plain `not(Goal)'. type_util.nl, switch_gen.nl: Higher-order pred types are not user-defined types. Add a `predtype' type category for them. call_gen.nl: Change call_closure/2 to call_closure/3 (with liveinfo). Plus a little bit of random hacking.
209 lines
7.1 KiB
Mathematica
209 lines
7.1 KiB
Mathematica
%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
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% File: implication.nl
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% Main author: squirrel (Jane Anna Langley)
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%
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% This module performs the inlining of implications as a part of the
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% language.
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%
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% This is a parse-tree to parse-tree transformation, to be performed
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% just before the parse-tree is converted to the hlds.
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% Immediately after this transformation is performed, negation is
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% pushed inwards by the transformations in the file negation.nl.
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%
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% This transformation also has the effect of converting all
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% occurrences of all(X,p(X)) to not(some(X, p(X))).
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%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
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:- module implication.
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:- interface.
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%-----------------------------------------------------------------------------%
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% PUBLIC PREDICATE DECLARATIONS:
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%-----------------------------------------------------------------------------%
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% dependencies
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:- import_module prog_io, io.
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:- pred implication__transform_operators(item_list, item_list,
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io__state, io__state).
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:- mode implication__transform_operators(in, out, di, uo) is det.
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:- pred implication__expand_implication(goal, goal, goal).
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:- mode implication__expand_implication(in, in, out) is det.
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:- pred implication__expand_equivalence(goal, goal, goal).
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:- mode implication__expand_equivalence(in, in, out) is det.
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%-----------------------------------------------------------------------------%
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% PUBLIC PREDICATE IMPLEMENTATIONS:
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%-----------------------------------------------------------------------------%
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:- implementation.
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% dependencies.
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:- import_module string, int, set, bintree, list, map, require, std_util.
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:- import_module term, term_io, varset.
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:- import_module prog_util, prog_out, hlds_out.
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:- import_module globals, options.
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:- import_module make_tags, quantification.
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:- import_module unify_proc, type_util.
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% implication__transform_operators/4
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% This is the top level, publically visible predicate of this
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% module.
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implication__transform_operators(Items_In, Items_Out) -->
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globals__io_lookup_bool_option(verbose, Verbose),
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maybe_write_string(Verbose,
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"% Transforming implication and equivalence..."),
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maybe_flush_output(Verbose),
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{ implication__transform_over_list(Items_In, Items_Out) },
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maybe_write_string(Verbose, " done.\n"),
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globals__io_lookup_bool_option(statistics, Statistics),
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maybe_report_stats(Statistics).
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% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - %
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implication__expand_implication(Goal1, Goal2, TransformedGoal) :-
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implication__transform_goal(implies(Goal1, Goal2), TransformedGoal).
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% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - %
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implication__expand_equivalence(Goal1, Goal2, TransformedGoal) :-
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implication__transform_goal(equivalent(Goal1, Goal2), TransformedGoal).
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%-----------------------------------------------------------------------------%
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% LOCAL PREDICATE DECLARATIONS:
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%-----------------------------------------------------------------------------%
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% Note: the types ``item_list'' and ``item_and_context'' are defined in
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% prog_io.nl
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:- pred implication__transform_over_list(item_list, item_list).
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:- mode implication__transform_over_list(in, out) is det.
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:- pred implication__transform_item_and_context(item_and_context,
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item_and_context).
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:- mode implication__transform_item_and_context(in, out) is det.
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:- pred implication__transform_item(item, item).
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:- mode implication__transform_item(in, out) is det.
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:- pred implication__transform_goal(goal, goal).
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:- mode implication__transform_goal(in, out) is det.
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%-----------------------------------------------------------------------------%
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% LOCAL PREDICATE IMPLEMENTATIONS:
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%-----------------------------------------------------------------------------%
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% implication__transform_over_list/2
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% This predicate simply maps the transformation
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% implication__transform_item_and_context onto every member of the
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% input list.
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implication__transform_over_list([], []).
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implication__transform_over_list([In|Ins], [Out|Outs]) :-
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implication__transform_item_and_context(In, Out),
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implication__transform_over_list(Ins, Outs).
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% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - %
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% implication__transform_item_and_context/2
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% Inlines the implication and equivalence operators
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% Note that the Context is unchanged and is just passed
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% straight through.
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% It simply strips off the Context and passes the
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% item on to implication__transform_item/2
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implication__transform_item_and_context((Item_In - Context_In),
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(Item_Out - Context_In)) :-
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implication__transform_item(Item_In, Item_Out).
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% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - %
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% implication__transform_item/2
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% Inlines the implication and equivalence operators.
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% If the item is a clause, it pulls out the goal and
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% transforms it, otherwise the item passes through
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% unchanged.
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implication__transform_item(Item_In, Item_Out) :-
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(
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Item_In = clause(Varset, Sym_name, Terms, Goal_In)
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->
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(
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implication__transform_goal(Goal_In, Goal_Out),
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Item_Out = clause(Varset, Sym_name, Terms, Goal_Out)
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)
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;
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Item_Out = Item_In
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).
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% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - %
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% implication__transform_goal/2
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% Implication
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implication__transform_goal(implies(P, Q), Goal_Out) :-
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implication__transform_goal(P, P1),
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implication__transform_goal(Q, Q1),
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Goal_Out = not((P1, not(Q1))).
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% Equivalence
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implication__transform_goal(equivalent(P, Q), Goal_Out) :-
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implication__transform_goal((implies(P,Q), implies(Q,P)),
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Goal_Out).
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% Existential Quantification
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implication__transform_goal(some(Vars, P), Goal_Out) :-
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implication__transform_goal(P, P1),
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Goal_Out = some(Vars, P1).
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% Universal Quantification
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implication__transform_goal(all(Vars, P), Goal_Out) :-
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implication__transform_goal(P, P1),
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Goal_Out = not(some(Vars, not(P1))).
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% Negation
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implication__transform_goal(not(P), Goal_Out) :-
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implication__transform_goal(P, P1),
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Goal_Out = not(P1).
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% Conjunction
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implication__transform_goal((P, Q), Goal_Out) :-
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implication__transform_goal(P, P1),
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implication__transform_goal(Q, Q1),
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Goal_Out = (P1, Q1).
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% Disjunction
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implication__transform_goal((P; Q), Goal_Out) :-
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implication__transform_goal(P, P1),
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implication__transform_goal(Q, Q1),
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Goal_Out = (P1; Q1).
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% If-Then
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implication__transform_goal(if_then(Vars, P, Q), Goal_Out) :-
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implication__transform_goal(P, P1),
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implication__transform_goal(Q, Q1),
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Goal_Out = if_then(Vars, P1, Q1).
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% If-Then-Else
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implication__transform_goal(if_then_else(Vars, P, Q, R), Goal_Out) :-
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implication__transform_goal(P, P1),
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implication__transform_goal(Q, Q1),
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implication__transform_goal(R, R1),
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Goal_Out = if_then_else(Vars, P1, Q1, R1).
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% Truth
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implication__transform_goal(true, true).
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% Falsehood
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implication__transform_goal(fail, fail).
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% Call
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implication__transform_goal(call(Term), call(Term)).
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% Unify
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implication__transform_goal(unify(Term1, Term2), unify(Term1, Term2)).
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% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - %
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