/* Part of SWI-Prolog Author: Jan Wielemaker E-mail: J.Wielemaker@vu.nl WWW: http://www.swi-prolog.org Copyright (c) 1985-2018, University of Amsterdam, VU University Amsterdam 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_explain, [ explain/1, explain/2 ]). :- autoload(library(apply),[maplist/2,maplist/3]). :- autoload(library(lists),[flatten/2]). :- if(exists_source(library(pldoc/man_index))). :- autoload(library(pldoc/man_index), [man_object_property/2]). :- endif. /** 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 % % Give an explanation on Term. The argument may be any Prolog data % object. If the argument is an atom, a term of the form `Name/Arity` % or a term of the form `Module:Name/Arity`, explain/1 describes the % predicate as well as possible references to it. See also gxref/0. explain(Item) :- explain(Item, Explanation), writeln(Explanation), fail. explain(_). /******************************** * BASIC TYPES * *********************************/ %! explain(@Term, -Explanation) is nondet. % % True when Explanation is an explanation of 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(M:Head) :- var(M), current_predicate(_, M2:Head), ( predicate_property(M2:Head, imported_from(M)) -> true ; M = M2 ), !. 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) ). :- if(current_predicate(man_object_property/2)). explain_predicate(Pred, Explanation) :- Pred = _Module:Head, functor(Head, Name, Arity), man_object_property(Name/Arity, summary(Summary)), source_file(Pred, File), current_prolog_flag(home, Home), sub_atom(File, 0, _, _, Home), utter(Explanation, '~t~8|Summary: ``~w''''', [Summary]). :- endif. 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).