1/*  Part of SWI-Prolog
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  1985-2002, University of Amsterdam
    7    All rights reserved.
    8
    9    Redistribution and use in source and binary forms, with or without
   10    modification, are permitted provided that the following conditions
   11    are met:
   12
   13    1. Redistributions of source code must retain the above copyright
   14       notice, this list of conditions and the following disclaimer.
   15
   16    2. Redistributions in binary form must reproduce the above copyright
   17       notice, this list of conditions and the following disclaimer in
   18       the documentation and/or other materials provided with the
   19       distribution.
   20
   21    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   22    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   23    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   24    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   25    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   26    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   27    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   28    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   29    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   31    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   32    POSSIBILITY OF SUCH DAMAGE.
   33*/
   34
   35:- module(online_help,
   36          [ help/1,
   37            help/0,
   38            apropos/1
   39          ]).   40:- use_module(lists, [append/3, member/2]).   41
   42:- if(exists_source(library(helpidx))).   43:- use_module(library(helpidx)).   44no_help :-
   45    fail.
   46:- else.   47no_help :-
   48    print_message(warning, no_help_files).
   49function(_,_,_).                        % make check silent
   50predicate(_,_,_,_,_).
   51section(_,_,_,_).
   52:- endif.   53
   54:- multifile
   55    prolog:help_hook/1,             % Generic help hook.
   56    prolog:show_help_hook/2.        % +Title, +TmpFile
   57
   58/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
   59This module  defines the  online  help  facility of   SWI-Prolog.   It
   60assumes  (Prolog) index file  at library(help_index)   and  the actual
   61manual  at library(online_manual).   Output  is piped through  a  user
   62defined pager, which defaults to `more'.
   63- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
   64
   65%       help/0
   66
   67help :-
   68    no_help,
   69    !.
   70help :-
   71    prolog:help_hook(help),
   72    !.
   73help :-
   74    help(help/1).

 help(+Subject)

Display online help on specified subject.

   80help(_) :-
   81    no_help,
   82    !.
   83help(What) :-
   84    prolog:help_hook(help(What)),
   85    !.
   86help(What) :-
   87    give_help(What).

 apropos(Pattern)

Give a list of subjects that might be appropriate.

   92apropos(_) :-
   93    no_help,
   94    !.
   95apropos(What) :-
   96    prolog:help_hook(apropos(What)),
   97    !.
   98apropos(What) :-
   99    give_apropos(What).
  100
  101give_help(Name/Arity) :-
  102    !,
  103    predicate(Name, Arity, _, From, To),
  104    !,
  105    show_help(Name/Arity, [From-To]).
  106give_help(Section) :-
  107    user_index(Index, Section),
  108    !,
  109    section(Index, _, From, To),
  110    show_help(Section, [From-To]).
  111give_help(Function) :-
  112    atom(Function),
  113    atom_concat('PL_', _, Function),
  114    function(Function, From, To),
  115    !,
  116    show_help(Function, [From-To]).
  117give_help(Name) :-
  118    findall(From-To, predicate(Name, _, _, From, To), Ranges),
  119    Ranges \== [],
  120    !,
  121    show_help(Name, Ranges).
  122give_help(What) :-
  123    format('No help available for ~w~n', [What]).

 show_help(+ListOfRanges)

Pipe specified ranges of the manual through the user defined pager

  128:- dynamic asserted_help_tmp_file/1.  129
  130help_tmp_file(X) :-
  131    asserted_help_tmp_file(X),
  132    !.
  133help_tmp_file(X) :-
  134    tmp_file(manual, X),
  135    asserta(asserted_help_tmp_file(X)).
  136
  137write_ranges_to_file(Ranges, Outfile) :-
  138    online_manual_stream(Manual),
  139    help_tmp_file(Outfile),
  140    open(Outfile, write, Output),
  141    show_ranges(Ranges, Manual, Output),
  142    close(Manual),
  143    close(Output).
  144
  145show_help(Title, Ranges) :-
  146    predicate_property(prolog:show_help_hook(_,_), number_of_clauses(N)),
  147    N > 0,
  148    write_ranges_to_file(Ranges, TmpFile),
  149    prolog:show_help_hook(Title, TmpFile).
  150show_help(_, Ranges) :-
  151    current_prolog_flag(pipe, true),
  152    !,
  153    online_manual_stream(Manual),
  154    pager_stream(Pager),
  155    catch(show_ranges(Ranges, Manual, Pager), _, true),
  156    close(Manual),
  157    catch(close(Pager), _, true).
  158show_help(_, Ranges) :-
  159    online_manual_stream(Manual),
  160    show_ranges(Ranges, Manual, user_output).
  161
  162show_ranges([], _, _) :- !.
  163show_ranges([FromLine-ToLine|Rest], Manual, Pager) :-
  164    line_start(FromLine, From),
  165    line_start(ToLine, To),
  166    seek(Manual, From, bof, _),
  167    Range is To - From,
  168    copy_chars(Range, Manual, Pager),
  169    nl(Pager),
  170    show_ranges(Rest, Manual, Pager).

 copy_chars(+Count, +FromStream, +ToStream)

Note: stream is binary to deal with byte offsets. As the data is ISO Latin-1 anyway, this is fine.

  177copy_chars(N, From, To) :-
  178    get0(From, C0),
  179    copy_chars(N, From, To, C0).
  180
  181copy_chars(N, _, _, _) :-
  182    N =< 0,
  183    !.
  184copy_chars(N, _, To, _) :-
  185    0 =:= N mod 4096,
  186    flush_output(To),
  187    fail.
  188copy_chars(N, From, To, C) :-
  189    get_byte(From, C1),
  190    (   C1 == 8,                    % backspace
  191        \+ current_prolog_flag(write_help_with_overstrike, true)
  192    ->  get_byte(From, C2),
  193        NN is N - 2,
  194        copy_chars(NN, From, To, C2)
  195    ;   put_printable(To, C),
  196        NN is N - 1,
  197        copy_chars(NN, From, To, C1)
  198    ).
  199
  200put_printable(_, 12) :- !.
  201put_printable(_, 13) :- !.
  202put_printable(_, -1) :- !.
  203put_printable(To, C) :-
  204    put_code(To, C).
  205
  206online_manual_stream(Stream) :-
  207    find_manual(Manual),
  208    open(Manual, read, Stream, [type(binary)]).
  209
  210pager_stream(Stream) :-
  211    find_pager(Pager),
  212    open(pipe(Pager), write, Stream).
  213
  214find_manual(Path) :-
  215    absolute_file_name(library('MANUAL'), Path, [access(read)]).
  216
  217find_pager(Pager) :-
  218    getenv('PAGER', Pager),
  219    !.
  220find_pager(more).
  221
  222/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  223Set the write_help_with_overstrike feature.
  224- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  225
  226set_overstrike_feature :-
  227    current_prolog_flag(write_help_with_overstrike, _),
  228    !.
  229set_overstrike_feature :-
  230    (   getenv('TERM', xterm)
  231    ->  Flag = true
  232    ;   Flag = false
  233    ),
  234    create_prolog_flag(write_help_with_overstrike, Flag, []).
  235
  236:- initialization set_overstrike_feature.

 line_start(Line, Start) is det

True if Start is the byte position at which Line starts.

  242:- dynamic
  243    start_of_line/2.  244
  245line_start(Line, Start) :-
  246    start_of_line(Line, Start),
  247    !.
  248line_start(Line, Start) :-
  249    line_index,
  250    start_of_line(Line, Start).

 line_index

Create index holding the byte positions for the line starts

  257line_index :-
  258    start_of_line(_,_),
  259    !.
  260line_index :-
  261    online_manual_stream(Stream),
  262    set_stream(Stream, encoding(octet)),
  263    call_cleanup(line_index(Stream, 1), close(Stream)).
  264
  265line_index(Stream, LineNo) :-
  266    byte_count(Stream, ByteNo),
  267    assert(start_of_line(LineNo, ByteNo)),
  268    (   at_end_of_stream(Stream)
  269    ->  true
  270    ;   LineNo2 is LineNo+1,
  271        skip(Stream, 10),
  272        line_index(Stream, LineNo2)
  273    ).
  274
  275
  276                 /*******************************
  277                 *             APROPOS          *
  278                 *******************************/
  279
  280give_apropos(Atom) :-
  281    ignore(predicate_apropos(Atom)),
  282    ignore(function_apropos(Atom)),
  283    ignore(section_apropos(Atom)).
  284
  285apropos_predicate(Pattern, Name, Arity, Summary) :-
  286    predicate(Name, Arity, Summary, _, _),
  287    (   apropos_match(Pattern, Name)
  288    ->  true
  289    ;   apropos_match(Pattern, Summary)
  290    ).
  291
  292predicate_apropos(Pattern) :-
  293    findall(Name-Arity-Summary,
  294            apropos_predicate(Pattern, Name, Arity, Summary),
  295            Names),
  296    forall(member(Name-Arity-Summary, Names),
  297           format('~w/~w~t~30|~w~n', [Name, Arity, Summary])).
  298
  299function_apropos(Pattern) :-
  300    findall(Name, (function(Name, _, _),
  301                   apropos_match(Pattern, Name)), Names),
  302    forall(member(Name, Names),
  303           format('Interface Function~t~30|~w()~n', Name)).
  304
  305section_apropos(Pattern) :-
  306    findall(Index-Name, (section(Index, Name, _, _),
  307                   apropos_match(Pattern, Name)), Names),
  308    forall(member(Index-Name, Names),
  309           (user_index(Index, UserIndex),
  310            format('Section ~w~t~30|"~w"~n', [UserIndex, Name]))).
  311
  312apropos_match(Needle, Haystack) :-
  313    sub_atom_icasechk(Haystack, _, Needle).
  314
  315user_index(List, Index) :-
  316    is_list(List),
  317    !,
  318    to_user_index(List, S),
  319    name(Index, S).
  320user_index(List, Index) :-
  321    to_system_index(Index, List).
  322
  323to_user_index([], []).
  324to_user_index([A], S) :-
  325    !,
  326    name(A, S).
  327to_user_index([A|B], S) :-
  328    name(A, S0),
  329    append(S0, [0'-], S1),
  330    append(S1, Rest, S),
  331    to_user_index(B, Rest).
  332
  333to_system_index(A-B, I) :-
  334    !,
  335    to_system_index(A, C),
  336    integer(B),
  337    append(C, [B], I).
  338to_system_index(A, [A]) :-
  339    integer(A).
  340
  341                 /*******************************
  342                 *            MESSAGES          *
  343                 *******************************/
  344
  345:- multifile
  346    prolog:message/3.  347
  348prolog:message(no_help_files) -->
  349    [ 'The online help files (helpidx.pl, MANUAL) are not installed.', nl,
  350      'If you installed SWI-Prolog from GIT/CVS, please consult', nl,
  351      'README.doc and README.git in the toplevel of the sources.'
  352    ]