/* $Id: help.pl,v 1.22 2006/08/10 13:45:47 jan Exp $ Part of SWI-Prolog Author: Jan Wielemaker E-mail: jan@swi.psy.uva.nl WWW: http://www.swi-prolog.org Copyright (C): 1985-2002, University of 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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(online_help, [ help/1 , help/0 , apropos/1 ]). :- use_module(lists, [append/3, member/2]). :- use_module(library(helpidx)). :- multifile prolog:help_hook/1. % Generic help hook. /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - This module defines the online help facility of SWI-Prolog. It assumes (Prolog) index file at library(help_index) and the actual manual at library(online_manual). Output is piped through a user defined pager, which defaults to `more'. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ % help/0 help :- prolog:help_hook(help), !. help :- help(help/1). %% help(+Subject) % % Display online help on specified subject. help(What) :- prolog:help_hook(help(What)), !. help(What) :- give_help(What). %% apropos(Pattern) % Give a list of subjects that might be appropriate. apropos(What) :- prolog:help_hook(apropos(What)), !. apropos(What) :- give_apropos(What). give_help(Name/Arity) :- !, predicate(Name, Arity, _, From, To), !, show_help(Name/Arity, [From-To]). give_help(Section) :- user_index(Index, Section), !, section(Index, _, From, To), show_help(Section, [From-To]). give_help(Function) :- atom(Function), atom_concat('PL_', _, Function), function(Function, From, To), !, show_help(Function, [From-To]). give_help(Name) :- findall(From-To, predicate(Name, _, _, From, To), Ranges), Ranges \== [], !, show_help(Name, Ranges). give_help(What) :- format('No help available for ~w~n', What). %% show_help(+ListOfRanges) % Pipe specified ranges of the manual through the user defined pager :- dynamic asserted_help_tmp_file/1. help_tmp_file(X) :- asserted_help_tmp_file(X), !. help_tmp_file(X) :- tmp_file(manual, X), asserta(asserted_help_tmp_file(X)). write_ranges_to_file(Ranges, Outfile) :- online_manual_stream(Manual), help_tmp_file(Outfile), open(Outfile, write, Output), show_ranges(Ranges, Manual, Output), close(Manual), close(Output). show_help(Title, Ranges) :- current_predicate(_, show_help_hook(_,_)), write_ranges_to_file(Ranges, TmpFile), user:show_help_hook(Title, TmpFile). show_help(_, Ranges) :- clause(running_under_emacs_interface, _), running_under_emacs_interface, !, write_ranges_to_file(Ranges, Outfile), call_emacs('(view-file-other-window "~w")', [Outfile]). show_help(_, Ranges) :- current_prolog_flag(pipe, true), !, online_manual_stream(Manual), pager_stream(Pager), catch(show_ranges(Ranges, Manual, Pager), _, true), close(Manual), catch(close(Pager), _, true). show_help(_, Ranges) :- online_manual_stream(Manual), show_ranges(Ranges, Manual, user_output). show_ranges([], _, _) :- !. show_ranges([From-To|Rest], Manual, Pager) :- seek(Manual, From, bof, _), Range is To - From, copy_chars(Range, Manual, Pager), nl(Pager), show_ranges(Rest, Manual, Pager). copy_chars(N, From, To) :- get0(From, C0), copy_chars(N, From, To, C0). copy_chars(N, _, _, _) :- N =< 0, !. copy_chars(N, _, To, _) :- 0 =:= N mod 4096, flush_output(To), fail. copy_chars(N, From, To, C) :- get0(From, C1), ( C1 == 8, % backspace \+ current_prolog_flag(write_help_with_overstrike, true) -> get0(From, C2), NN is N - 2, copy_chars(NN, From, To, C2) ; put_printable(To, C), NN is N - 1, copy_chars(NN, From, To, C1) ). put_printable(_, 12) :- !. put_printable(_, -1) :- !. put_printable(To, C) :- put(To, C). online_manual_stream(Stream) :- find_manual(Manual), open(Manual, read, Stream). pager_stream(Stream) :- find_pager(Pager), open(pipe(Pager), write, Stream). find_manual(Path) :- absolute_file_name(library('MANUAL'), [access(read)], Path). find_pager(Pager) :- getenv('PAGER', Pager), !. find_pager(more). /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Set the write_help_with_overstrike feature. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ set_overstrike_feature :- current_prolog_flag(write_help_with_overstrike, _), !. set_overstrike_feature :- getenv('TERM', xterm), !, set_prolog_flag(write_help_with_overstrike, true). set_overstrike_feature :- set_prolog_flag(write_help_with_overstrike, false). :- initialization set_overstrike_feature. % APROPOS give_apropos(Atom) :- ignore(predicate_apropos(Atom)), ignore(function_apropos(Atom)), ignore(section_apropos(Atom)). apropos_predicate(Pattern, Name, Arity, Summary) :- predicate(Name, Arity, Summary, _, _), ( apropos_match(Pattern, Name) -> true ; apropos_match(Pattern, Summary) ). predicate_apropos(Pattern) :- findall(Name-Arity-Summary, apropos_predicate(Pattern, Name, Arity, Summary), Names), forall(member(Name-Arity-Summary, Names), format('~w/~w~t~30|~w~n', [Name, Arity, Summary])). function_apropos(Pattern) :- findall(Name, (function(Name, _, _), apropos_match(Pattern, Name)), Names), forall(member(Name, Names), format('Interface Function~t~30|~w()~n', Name)). section_apropos(Pattern) :- findall(Index-Name, (section(Index, Name, _, _), apropos_match(Pattern, Name)), Names), forall(member(Index-Name, Names), (user_index(Index, UserIndex), format('Section ~w~t~30|"~w"~n', [UserIndex, Name]))). apropos_match(A, B) :- '$apropos_match'(A, B). % C defined for performance user_index(List, Index) :- is_list(List), !, to_user_index(List, S), name(Index, S). user_index(List, Index) :- to_system_index(Index, List). to_user_index([], ""). to_user_index([A], S) :- !, name(A, S). to_user_index([A|B], S) :- name(A, S0), append(S0, "-", S1), append(S1, Rest, S), to_user_index(B, Rest). to_system_index(A-B, I) :- !, to_system_index(A, C), integer(B), append(C, [B], I). to_system_index(A, [A]) :- integer(A).