/* Part of SWI-Prolog Author: Eva Stoewe, Guenter Kniesel and Jan Wielemaker E-mail: pdt@lists.iai.uni-bonn.de WWW: http://sewiki.iai.uni-bonn.de/research/pdt/start Copyright (c) 2004-2012, CS Dept. III, University of Bonn All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ :- module(prolog_metainference, [ infer_meta_predicate/2, % :Head, -MetaSpec inferred_meta_predicate/2 % :Head, ?MetaSpec ]). :- autoload(library(apply),[maplist/4]). :- autoload(library(lists),[append/3]). :- meta_predicate inferred_meta_predicate(:, ?), infer_meta_predicate(:, -). :- dynamic inferred_meta_pred/3. % Head, Module, Meta /** Infer meta-predicate properties This module infers meta-predicate properties by inspecting the clauses of predicates that call other predicates. This is extremely useful for program analysis and refactoring because many programs `in the wild' have incomplete or incorrect meta-predicate information. @see This library is used by prolog_walk_code/1 to improve the accuracy of this analysis. @tbd Re-introduce some alias-analysis @tbd Not all missing meta-declarations are interesting. Notably, meta-predicates that are private and only pass meta-arguments on behalve of a public meta-predicates do not need a declaration. */ %! inferred_meta_predicate(:Head, ?MetaSpec) is nondet. % % True when MetaSpec is an inferred meta-predicate specification % for Head. inferred_meta_predicate(M:Head, MetaSpec) :- inferred_meta_pred(Head, M, MetaSpec). inferred_meta_predicate(M:Head, MetaSpec) :- predicate_property(M:Head, imported_from(From)), inferred_meta_pred(Head, From, MetaSpec). %! infer_meta_predicate(:Head, -MetaSpec) is semidet % % True when MetaSpec is a meta-predicate specifier for the % predicate Head. Derived meta-predicates are collected and made % available through inferred_meta_predicate/2. infer_meta_predicate(Head, MetaSpec) :- inferred_meta_predicate(Head, MetaSpec), !. infer_meta_predicate(M:Head, MetaSpec) :- predicate_property(M:Head, imported_from(From)), !, do_infer_meta_predicate(From:Head, MetaSpec), assertz(inferred_meta_pred(Head, From, MetaSpec)). infer_meta_predicate(M:Head, MetaSpec) :- do_infer_meta_predicate(M:Head, MetaSpec), assertz(inferred_meta_pred(Head, M, MetaSpec)). :- meta_predicate do_infer_meta_predicate(:, -). do_infer_meta_predicate(Module:AHead, MetaSpec):- functor(AHead, Functor, Arity), functor(Head, Functor, Arity), % Generalise the head findall(MetaSpec, meta_pred_args_in_clause(Module, Head, MetaSpec), MetaSpecs), MetaSpecs \== [], combine_meta_args(MetaSpecs, MetaSpec). %! meta_pred_args_in_clause(+Module, +Head, -MetaSpec) is nondet. meta_pred_args_in_clause(Module, Head, MetaArgs) :- clause(Module:Head, Body), annotate_meta_vars_in_body(Body, Module), meta_annotation(Head, MetaArgs). %! annotate_meta_vars_in_body(+Term, +Module) is det % % Annotate variables in Term if they appear as meta-arguments. % % @tbd Aliasing. Previous code detected aliasing for % - =/2 % - functor/3 % - atom_concat/3 % - =../2 % - arg/3 % @tbd We can make this nondet, exploring multiple aliasing % paths in disjunctions. annotate_meta_vars_in_body(A, _) :- atomic(A), !. annotate_meta_vars_in_body(Var, _) :- var(Var), !, annotate(Var, 0). annotate_meta_vars_in_body(Module:Term, _) :- !, ( atom(Module) -> annotate_meta_vars_in_body(Term, Module) ; var(Module) -> annotate(Module, m) ; true % may continue if Term is a system ). % predicate? annotate_meta_vars_in_body((TermA, TermB), Module) :- !, annotate_meta_vars_in_body(TermB, Module), annotate_meta_vars_in_body(TermA, Module). annotate_meta_vars_in_body((TermA; TermB), Module) :- !, annotate_meta_vars_in_body(TermB, Module), annotate_meta_vars_in_body(TermA, Module). annotate_meta_vars_in_body((TermA->TermB), Module) :- !, annotate_meta_vars_in_body(TermB, Module), annotate_meta_vars_in_body(TermA, Module). annotate_meta_vars_in_body((TermA*->TermB), Module) :- !, annotate_meta_vars_in_body(TermB, Module), annotate_meta_vars_in_body(TermA, Module). annotate_meta_vars_in_body(A=B, _) :- var(A), var(B), !, A = B. annotate_meta_vars_in_body(Goal, Module) :- % TBD: do we trust this? predicate_property(Module:Goal, meta_predicate(Head)), !, functor(Goal, _, Arity), annotate_meta_args(1, Arity, Goal, Head, Module). annotate_meta_vars_in_body(Goal, Module) :- inferred_meta_predicate(Module:Goal, Head), !, functor(Goal, _, Arity), annotate_meta_args(1, Arity, Goal, Head, Module). annotate_meta_vars_in_body(_, _). %! annotate_meta_args(+Arg, +Arity, +Goal, +MetaSpec, +Module) annotate_meta_args(I, Arity, Goal, MetaSpec, Module) :- I =< Arity, !, arg(I, MetaSpec, MetaArg), arg(I, Goal, Arg), annotate_meta_arg(MetaArg, Arg, Module), I2 is I + 1, annotate_meta_args(I2, Arity, Goal, MetaSpec, Module). annotate_meta_args(_, _, _, _, _). annotate_meta_arg(Spec, Arg, _) :- var(Arg), !, annotate(Arg, Spec). annotate_meta_arg(0, Arg, Module) :- !, annotate_meta_vars_in_body(Arg, Module). annotate_meta_arg(N, Arg, Module) :- integer(N), callable(Arg), !, Arg =.. List, length(Extra, N), append(List, Extra, ListX), ArgX =.. ListX, annotate_meta_vars_in_body(ArgX, Module). annotate_meta_arg(Spec, Arg, _) :- is_meta(Spec), compound(Arg), Arg = Module:_, var(Module), !, annotate(Module, m). annotate_meta_arg(_,_,_). annotate(Var, Annotation) :- get_attr(Var, prolog_metainference, Annot0), !, join_annotation(Annot0, Annotation, Joined), put_attr(Var, prolog_metainference, Joined). annotate(Var, Annotation) :- put_attr(Var, prolog_metainference, Annotation). join_annotation(A, A, A) :- !. join_annotation(A, B, C) :- ( is_meta(A), \+ is_meta(B) -> C = A ; \+ is_meta(A), is_meta(B) -> C = B ; is_meta(A), is_meta(B) -> C = (:) ; C = * ). attr_unify_hook(A0, Other) :- get_attr(Other, prolog_metainference, A1), !, join_annotation(A0, A1, A), put_attr(Other, prolog_metainference, A). %! meta_annotation(+Head, -Annotation) is semidet. % % True when Annotation is an appropriate meta-specification for % Head. meta_annotation(Head, Meta) :- functor(Head, Name, Arity), functor(Meta, Name, Arity), meta_args(1, Arity, Head, Meta, HasMeta), HasMeta == true. meta_args(I, Arity, Head, Meta, HasMeta) :- I =< Arity, !, arg(I, Head, HeadArg), arg(I, Meta, MetaArg), meta_arg(HeadArg, MetaArg), ( is_meta(MetaArg) -> HasMeta = true ; true ), I2 is I + 1, meta_args(I2, Arity, Head, Meta, HasMeta). meta_args(_, _, _, _, _). is_meta(I) :- integer(I), !. is_meta(:). is_meta(^). is_meta(//). %! meta_arg(+AnnotatedArg, -MetaSpec) is det. % % True when MetaSpec is a proper annotation for the argument % AnnotatedArg. This is simple if the argument is a plain argument % in the head (first clause). If it is a compound term, it must % unify to _:_, otherwise there is no point turning it into a meta % argument. If the module part is then passed to a module % sensitive predicate, we assume it is a meta-predicate. meta_arg(HeadArg, MetaArg) :- get_attr(HeadArg, prolog_metainference, MetaArg), MetaArg \== m, !. meta_arg(HeadArg, :) :- compound(HeadArg), HeadArg = M:_, get_attr(M, prolog_metainference, m), !. meta_arg(_, *). %! combine_meta_args(+Heads, -Head) is det. % % Combine multiple meta-specifications. combine_meta_args([], []) :- !. combine_meta_args([List], List) :- !. combine_meta_args([Spec,Spec|Specs], CombinedArgs) :- !, combine_meta_args([Spec|Specs], CombinedArgs). combine_meta_args([Spec1,Spec2|Specs], CombinedArgs) :- Spec1 =.. [Name|Args1], Spec2 =.. [Name|Args2], maplist(join_annotation, Args1, Args2, Args), Spec =.. [Name|Args], combine_meta_args([Spec|Specs], CombinedArgs).