/* $Id$ Part of SWI-Prolog Author: Jan Wielemaker E-mail: J.Wielemaker@cs.vu.nl WWW: http://www.swi-prolog.org Copyright (C): 1985-2010, University of Amsterdam, VU University Amsterdam This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA As a special exception, if you link this library with other files, compiled with a Free Software compiler, to produce an executable, this library does not by itself cause the resulting executable to be covered by the GNU General Public License. This exception does not however invalidate any other reasons why the executable file might be covered by the GNU General Public License. */ :- module(prolog_explain, [ explain/1, explain/2 ]). :- use_module(library(helpidx)). :- use_module(library(lists)). :- use_module(library(apply)). /** Describe Prolog Terms The library(explain) describes prolog-terms. The most useful functionality is its cross-referencing function. == ?- explain(subset(_,_)). "subset(_, _)" is a compound term Referenced from 2-th clause of lists:subset/2 Referenced from 46-th clause of prolog_xref:imported/3 Referenced from 68-th clause of prolog_xref:imported/3 lists:subset/2 is a predicate defined in /staff/jan/lib/pl-5.6.17/library/lists.pl:307 Referenced from 2-th clause of lists:subset/2 Possibly referenced from 2-th clause of lists:subset/2 == Note that the help-tool for XPCE provides a nice graphical cross-referencer. */ %% explain(@Term) is det % % Write all information known about Term to the current output. explain(Item) :- explain(Item, Explanation), writeln(Explanation), fail. explain(_). /******************************** * BASIC TYPES * *********************************/ %% explain(@Term, -Explanation) is nondet. % % Explanation describes information about Term. explain(Var, Explanation) :- var(Var), !, utter(Explanation, '"~w" is an unbound variable', [Var]). explain(I, Explanation) :- integer(I), !, utter(Explanation, '"~w" is an integer', [I]). explain(F, Explanation) :- float(F), !, utter(Explanation, '"~w" is a floating point number', [F]). explain(S, Explanation) :- string(S), !, utter(Explanation, '"~w" is a string', S). explain([], Explanation) :- !, utter(Explanation, '"[]" is a special constant denoting an empty list', []). explain(A, Explanation) :- atom(A), utter(Explanation, '"~w" is an atom', [A]). explain(A, Explanation) :- atom(A), current_op(Pri, F, A), op_type(F, Type), utter(Explanation, '"~w" is a ~w (~w) operator of priority ~d', [A, Type, F, Pri]). explain(A, Explanation) :- atom(A), !, explain_atom(A, Explanation). explain([H|T], Explanation) :- is_list(T), !, List = [H|T], length(List, L), ( utter(Explanation, '"~p" is a proper list with ~d elements', [List, L]) ; maplist(printable, List), utter(Explanation, '~t~8|Text is "~s"', [List]) ). explain([H|T], Explanation) :- !, length([H|T], L), !, utter(Explanation, '"~p" is a not-closed list with ~d elements', [[H|T], L]). explain(Name/Arity, Explanation) :- atom(Name), integer(Arity), !, functor(Head, Name, Arity), known_predicate(Module:Head), ( Module == system -> true ; \+ predicate_property(Module:Head, imported_from(_)) ), explain_predicate(Module:Head, Explanation). explain(Module:Name/Arity, Explanation) :- atom(Module), atom(Name), integer(Arity), !, functor(Head, Name, Arity), explain_predicate(Module:Head, Explanation). explain(Module:Head, Explanation) :- callable(Head), !, explain_predicate(Module:Head, Explanation). explain(Term, Explanation) :- numbervars(Term, 0, _, [singletons(true)]), utter(Explanation, '"~W" is a compound term', [Term, [quoted(true), numbervars(true)]]). explain(Term, Explanation) :- explain_functor(Term, Explanation). %% known_predicate(:Head) % % Succeeds if we know anything about this predicate. Undefined % predicates are considered `known' for this purpose, so we can % provide referenced messages on them. known_predicate(Pred) :- current_predicate(_, Pred), !. known_predicate(Pred) :- predicate_property(Pred, undefined). known_predicate(_:Head) :- functor(Head, Name, Arity), '$in_library'(Name, Arity, _Path). op_type(X, prefix) :- atom_chars(X, [f, _]). op_type(X, infix) :- atom_chars(X, [_, f, _]). op_type(X, postfix) :- atom_chars(X, [_, f]). printable(C) :- integer(C), between(32, 126, C). /******************************** * ATOMS * *********************************/ explain_atom(A, Explanation) :- referenced(A, Explanation). explain_atom(A, Explanation) :- current_predicate(A, Module:Head), ( Module == system -> true ; \+ predicate_property(Module:Head, imported_from(_)) ), explain_predicate(Module:Head, Explanation). explain_atom(A, Explanation) :- predicate_property(Module:Head, undefined), functor(Head, A, _), explain_predicate(Module:Head, Explanation). /******************************** * FUNCTOR * *********************************/ explain_functor(Head, Explanation) :- referenced(Head, Explanation). explain_functor(Head, Explanation) :- current_predicate(_, Module:Head), \+ predicate_property(Module:Head, imported_from(_)), explain_predicate(Module:Head, Explanation). explain_functor(Head, Explanation) :- predicate_property(M:Head, undefined), ( functor(Head, N, A), utter(Explanation, '~w:~w/~d is an undefined predicate', [M,N,A]) ; referenced(M:Head, Explanation) ). /******************************** * PREDICATE * *********************************/ lproperty(built_in, ' built-in', []). lproperty(dynamic, ' dynamic', []). lproperty(multifile, ' multifile', []). lproperty(transparent, ' meta', []). tproperty(imported_from(Module), ' imported from module ~w', [Module]). tproperty(file(File), ' defined in~n~t~8|~w', [File]). tproperty(line_count(Number), ':~d', [Number]). tproperty(autoload, ' that can be autoloaded', []). combine_utterances(Pairs, Explanation) :- maplist(first, Pairs, Fmts), atomic_list_concat(Fmts, Format), maplist(second, Pairs, ArgList), flatten(ArgList, Args), utter(Explanation, Format, Args). first(A-_B, A). second(_A-B, B). %% explain_predicate(:Head, -Explanation) is det. explain_predicate(Pred, Explanation) :- Pred = Module:Head, functor(Head, Name, Arity), ( predicate_property(Pred, undefined) -> utter(Explanation, '~w:~w/~d is an undefined predicate', [Module,Name,Arity]) ; ( var(Module) -> U0 = '~w/~d is a' - [Name, Arity] ; U0 = '~w:~w/~d is a' - [Module, Name, Arity] ), findall(Fmt-Arg, (lproperty(Prop, Fmt, Arg), predicate_property(Pred, Prop)), U1), U2 = ' predicate' - [], findall(Fmt-Arg, (tproperty(Prop, Fmt, Arg), predicate_property(Pred, Prop)), U3), flatten([U0, U1, U2, U3], Utters), combine_utterances(Utters, Explanation) ). explain_predicate(Pred, Explanation) :- predicate_property(Pred, built_in), Pred = _Module:Head, functor(Head, Name, Arity), predicate(Name, Arity, Summary, _, _), utter(Explanation, '~t~8|Summary: ``~w''''', [Summary]). explain_predicate(Pred, Explanation) :- referenced(Pred, Explanation). /******************************** * REFERENCES * *********************************/ referenced(Term, Explanation) :- current_predicate(_, Module:Head), ( predicate_property(Module:Head, built_in) -> current_prolog_flag(access_level, system) ; true ), \+ predicate_property(Module:Head, imported_from(_)), Module:Head \= help_index:predicate(_,_,_,_,_), nth_clause(Module:Head, N, Ref), '$xr_member'(Ref, Term), utter_referenced(Module:Head, N, Ref, 'Referenced', Explanation). referenced(_:Head, Explanation) :- current_predicate(_, Module:Head), ( predicate_property(Module:Head, built_in) -> current_prolog_flag(access_level, system) ; true ), \+ predicate_property(Module:Head, imported_from(_)), nth_clause(Module:Head, N, Ref), '$xr_member'(Ref, Head), utter_referenced(Module:Head, N, Ref, 'Possibly referenced', Explanation). utter_referenced(_Module:class(_,_,_,_,_,_), _, _, _, _) :- current_prolog_flag(xpce, true), !, fail. utter_referenced(_Module:lazy_send_method(_,_,_), _, _, _, _) :- current_prolog_flag(xpce, true), !, fail. utter_referenced(_Module:lazy_get_method(_,_,_), _, _, _, _) :- current_prolog_flag(xpce, true), !, fail. utter_referenced(pce_xref:exported(_,_), _, _, _, _) :- !, fail. utter_referenced(pce_xref:defined(_,_,_), _, _, _, _) :- !, fail. utter_referenced(pce_xref:called(_,_,_), _, _, _, _) :- !, fail. utter_referenced(pce_principal:send_implementation(_, _, _), _, Ref, Text, Explanation) :- current_prolog_flag(xpce, true), !, xpce_method_id(Ref, Id), utter(Explanation, '~t~8|~w from ~w', [Text, Id]). utter_referenced(pce_principal:get_implementation(Id, _, _, _), _, Ref, Text, Explanation) :- current_prolog_flag(xpce, true), !, xpce_method_id(Ref, Id), utter(Explanation, '~t~8|~w from ~w', [Text, Id]). utter_referenced(Module:Head, N, _Ref, Text, Explanation) :- functor(Head, Name, Arity), utter(Explanation, '~t~8|~w from ~d-th clause of ~w:~w/~d', [Text, N, Module, Name, Arity]). xpce_method_id(Ref, Id) :- clause(Head, _Body, Ref), strip_module(Head, _, H), arg(1, H, Id). /******************************** * UTTER * *********************************/ utter(Explanation, Fmt, Args) :- format(string(Explanation), Fmt, Args).