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)  1998-2025, University of Amsterdam
    7                              VU University Amsterdam
    8                              SWI-Prolog Solutions b.v.
    9    All rights reserved.
   10
   11    Redistribution and use in source and binary forms, with or without
   12    modification, are permitted provided that the following conditions
   13    are met:
   14
   15    1. Redistributions of source code must retain the above copyright
   16       notice, this list of conditions and the following disclaimer.
   17
   18    2. Redistributions in binary form must reproduce the above copyright
   19       notice, this list of conditions and the following disclaimer in
   20       the documentation and/or other materials provided with the
   21       distribution.
   22
   23    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   24    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   25    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   26    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   27    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   28    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   29    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   30    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   31    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   32    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   33    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   34    POSSIBILITY OF SUCH DAMAGE.
   35*/
   36
   37:- module(prolog_edit,
   38          [ edit/1,                     % +Spec
   39            edit/0
   40          ]).   41:- autoload(library(lists), [member/2, append/3, select/3]).   42:- autoload(library(make), [make/0]).   43:- if(exists_source(library(pce))).   44:- autoload(library(pce), [in_pce_thread/1]).   45:- autoload(library(pce_emacs), [emacs/1]).   46:- endif.   47:- autoload(library(prolog_breakpoints), [breakpoint_property/2]).   48:- autoload(library(apply), [foldl/5, maplist/3, maplist/2]).   49:- use_module(library(dcg/high_order), [sequence/5]).   50:- autoload(library(readutil), [read_line_to_string/2]).   51
   52
   53% :- set_prolog_flag(generate_debug_info, false).
   54
   55/** <module> Editor interface
   56
   57This module implements the generic editor  interface. It consists of two
   58extensible parts with little  in  between.   The  first  part deals with
   59translating the input into source-location, and the second with starting
   60an editor.
   61*/
   62
   63:- multifile
   64    locate/3,                       % +Partial, -FullSpec, -Location
   65    locate/2,                       % +FullSpec, -Location
   66    select_location/3,              % +Pairs, +Spec, -Location
   67    exists_location/1,              % +Location
   68    user_select/2,                  % +Max, -I
   69    edit_source/1,                  % +Location
   70    edit_command/2,                 % +Editor, -Command
   71    load/0.                         % provides load-hooks
   72
   73%!  edit(+Spec)
   74%
   75%   Edit indicated object.
   76
   77edit(Spec) :-
   78    notrace(edit_no_trace(Spec)).
   79
   80edit_no_trace(Spec) :-
   81    var(Spec),
   82    !,
   83    throw(error(instantiation_error, _)).
   84edit_no_trace(Spec) :-
   85    load_extensions,
   86    findall(Location-FullSpec,
   87            locate(Spec, FullSpec, Location),
   88            Pairs0),
   89    sort(Pairs0, Pairs1),
   90    merge_locations(Pairs1, Pairs),
   91    do_select_location(Pairs, Spec, Location),
   92    do_edit_source(Location).
   93
   94%!  edit
   95%
   96%   Edit associated or script file.  This is the Prolog file opened
   97%   by double-clicking or the file loaded using
   98%
   99%     ==
  100%     % swipl [-s] file.pl
  101%     ==
  102
  103edit :-
  104    current_prolog_flag(associated_file, File),
  105    !,
  106    edit(file(File)).
  107edit :-
  108    '$cmd_option_val'(script_file, OsFiles),
  109    OsFiles = [OsFile],
  110    !,
  111    prolog_to_os_filename(File, OsFile),
  112    edit(file(File)).
  113edit :-
  114    throw(error(context_error(edit, no_default_file), _)).
  115
  116
  117                 /*******************************
  118                 *            LOCATE            *
  119                 *******************************/
  120
  121%!  locate(+Spec, -FullSpec, -Location:dict)
  122
  123locate(FileSpec:Line, file(Path, line(Line)), #{file:Path, line:Line}) :-
  124    integer(Line), Line >= 1,
  125    ground(FileSpec),                      % so specific; do not try alts
  126    !,
  127    locate(FileSpec, _, #{file:Path}).
  128locate(FileSpec:Line:LinePos,
  129       file(Path, line(Line), linepos(LinePos)),
  130       #{file:Path, line:Line, linepos:LinePos}) :-
  131    integer(Line), Line >= 1,
  132    integer(LinePos), LinePos >= 1,
  133    ground(FileSpec),                      % so specific; do not try alts
  134    !,
  135    locate(FileSpec, _, #{file:Path}).
  136locate(Path, file(Path), #{file:Path}) :-
  137    atom(Path),
  138    exists_file(Path).
  139locate(Pattern, file(Path), #{file:Path}) :-
  140    atom(Pattern),
  141    catch(expand_file_name(Pattern, Files), error(_,_), fail),
  142    member(Path, Files),
  143    exists_file(Path).
  144locate(FileBase, file(File), #{file:File}) :-
  145    atom(FileBase),
  146    find_source(FileBase, File).
  147locate(FileSpec, file(File), #{file:File}) :-
  148    is_file_search_spec(FileSpec),
  149    find_source(FileSpec, File).
  150locate(FileBase, source_file(Path),  #{file:Path}) :-
  151    atom(FileBase),
  152    source_file(Path),
  153    file_base_name(Path, File),
  154    (   File == FileBase
  155    ->  true
  156    ;   file_name_extension(FileBase, _, File)
  157    ).
  158locate(FileBase, include_file(Path),  #{file:Path}) :-
  159    atom(FileBase),
  160    setof(Path, include_file(Path), Paths),
  161    member(Path, Paths),
  162    file_base_name(Path, File),
  163    (   File == FileBase
  164    ->  true
  165    ;   file_name_extension(FileBase, _, File)
  166    ).
  167locate(Name, FullSpec, Location) :-
  168    atom(Name),
  169    locate(Name/_, FullSpec, Location).
  170locate(Name/Arity, Module:Name/Arity, Location) :-
  171    locate(Module:Name/Arity, Location).
  172locate(Name//DCGArity, FullSpec, Location) :-
  173    (   integer(DCGArity)
  174    ->  Arity is DCGArity+2,
  175        locate(Name/Arity, FullSpec, Location)
  176    ;   locate(Name/_, FullSpec, Location) % demand arity >= 2
  177    ).
  178locate(Name/Arity, library(File),  #{file:PlPath}) :-
  179    atom(Name),
  180    '$in_library'(Name, Arity, Path),
  181    (   absolute_file_name(library(.), Dir,
  182                           [ file_type(directory),
  183                             solutions(all)
  184                           ]),
  185        atom_concat(Dir, File0, Path),
  186        atom_concat(/, File, File0)
  187    ->  find_source(Path, PlPath)
  188    ;   fail
  189    ).
  190locate(Module:Name, Module:Name/Arity, Location) :-
  191    locate(Module:Name/Arity, Location).
  192locate(Module:Head, Module:Name/Arity, Location) :-
  193    callable(Head),
  194    \+ ( Head = (PName/_),
  195         atom(PName)
  196       ),
  197    functor(Head, Name, Arity),
  198    locate(Module:Name/Arity, Location).
  199locate(Spec, module(Spec), Location) :-
  200    locate(module(Spec), Location).
  201locate(Spec, Spec, Location) :-
  202    locate(Spec, Location).
  203
  204include_file(Path) :-
  205    source_file_property(Path, included_in(_,_)).
  206
  207%!  is_file_search_spec(@Spec) is semidet.
  208%
  209%   True if Spec is valid pattern for absolute_file_name/3.
  210
  211is_file_search_spec(Spec) :-
  212    compound(Spec),
  213    compound_name_arguments(Spec, Alias, [Arg]),
  214    is_file_spec(Arg),
  215    user:file_search_path(Alias, _),
  216    !.
  217
  218is_file_spec(Name), atom(Name) => true.
  219is_file_spec(Name), string(Name) => true.
  220is_file_spec(Term), cyclic_term(Term) => fail.
  221is_file_spec(A/B) => is_file_spec(A), is_file_spec(B).
  222
  223%!  find_source(++FileSpec, =File) is semidet.
  224%
  225%   Find a source file from FileSpec.  If FileSpec resolves to a .qlf
  226%   file, File is the embedded `.pl` file (which may not exist).
  227
  228find_source(FileSpec, File) :-
  229    catch(absolute_file_name(FileSpec, File0,
  230                             [ file_type(prolog),
  231                               access(read),
  232                               file_errors(fail)
  233                             ]),
  234          error(_,_), fail),
  235    prolog_source(File0, File).
  236
  237prolog_source(File0, File) :-
  238    file_name_extension(_, Ext, File0),
  239    user:prolog_file_type(Ext, qlf),
  240    !,
  241    '$qlf_module'(File0, Info),
  242    File = Info.get(file).
  243prolog_source(File, File).
  244
  245
  246%!  locate(+Spec, -Location)
  247%
  248%   Locate object from the specified location.
  249
  250locate(file(File, line(Line)), #{file:File, line:Line}).
  251locate(file(File), #{file:File}).
  252locate(Module:Name/Arity, #{file:File, line:Line}) :-
  253    (   atom(Name), integer(Arity)
  254    ->  functor(Head, Name, Arity)
  255    ;   Head = _                    % leave unbound
  256    ),
  257    (   (   var(Module)
  258        ;   var(Name)
  259        )
  260    ->  NonImport = true
  261    ;   NonImport = false
  262    ),
  263    current_predicate(Name, Module:Head),
  264    \+ (   NonImport == true,
  265           Module \== system,
  266           predicate_property(Module:Head, imported_from(_))
  267       ),
  268    functor(Head, Name, Arity),     % bind arity
  269    predicate_property(Module:Head, file(File)),
  270    predicate_property(Module:Head, line_count(Line)).
  271locate(module(Module), Location) :-
  272    atom(Module),
  273    module_property(Module, file(Path)),
  274    (   module_property(Module, line_count(Line))
  275    ->  Location = #{file:Path, line:Line}
  276    ;   Location = #{file:Path}
  277    ).
  278locate(breakpoint(Id), Location) :-
  279    integer(Id),
  280    breakpoint_property(Id, clause(Ref)),
  281    (   breakpoint_property(Id, file(File)),
  282        breakpoint_property(Id, line_count(Line))
  283    ->  Location =  #{file:File, line:Line}
  284    ;   locate(clause(Ref), Location)
  285    ).
  286locate(clause(Ref), #{file:File, line:Line}) :-
  287    clause_property(Ref, file(File)),
  288    clause_property(Ref, line_count(Line)).
  289locate(clause(Ref, _PC), #{file:File, line:Line}) :- % TBD: use clause
  290    clause_property(Ref, file(File)),
  291    clause_property(Ref, line_count(Line)).
  292
  293
  294                 /*******************************
  295                 *             EDIT             *
  296                 *******************************/
  297
  298%!  do_edit_source(+Location)
  299%
  300%   Actually call the editor to edit Location, a list of Name(Value)
  301%   that contains file(File) and may contain line(Line). First the
  302%   multifile hook edit_source/1 is called. If this fails the system
  303%   checks for XPCE and the prolog-flag editor. If the latter is
  304%   built_in or pce_emacs, it will start PceEmacs.
  305%
  306%   Finally, it will get the editor to use from the prolog-flag
  307%   editor and use edit_command/2 to determine how this editor
  308%   should be called.
  309
  310do_edit_source(Location) :-             % hook
  311    edit_source(Location),
  312    !.
  313:- if(current_predicate(emacs/1)).  314do_edit_source(Location) :-             % PceEmacs
  315    current_prolog_flag(editor, Editor),
  316    pceemacs(Editor),
  317    current_prolog_flag(gui, true),
  318    !,
  319    location_url(Location, URL),        % File[:Line[:LinePos]]
  320    in_pce_thread(emacs(URL)).
  321:- endif.  322do_edit_source(Location) :-             % External editor
  323    external_edit_command(Location, Command),
  324    print_message(informational, edit(waiting_for_editor)),
  325    (   catch(shell(Command), E,
  326              (print_message(warning, E),
  327               fail))
  328    ->  print_message(informational, edit(make)),
  329        make
  330    ;   print_message(informational, edit(canceled))
  331    ).
  332
  333external_edit_command(Location, Command) :-
  334    #{file:File, line:Line} :< Location,
  335    editor(Editor),
  336    file_base_name(Editor, EditorFile),
  337    file_name_extension(Base, _, EditorFile),
  338    edit_command(Base, Cmd),
  339    prolog_to_os_filename(File, OsFile),
  340    atom_codes(Cmd, S0),
  341    substitute('%e', Editor, S0, S1),
  342    substitute('%f', OsFile, S1, S2),
  343    substitute('%d', Line,   S2, S),
  344    !,
  345    atom_codes(Command, S).
  346external_edit_command(Location, Command) :-
  347    #{file:File} :< Location,
  348    editor(Editor),
  349    file_base_name(Editor, EditorFile),
  350    file_name_extension(Base, _, EditorFile),
  351    edit_command(Base, Cmd),
  352    prolog_to_os_filename(File, OsFile),
  353    atom_codes(Cmd, S0),
  354    substitute('%e', Editor, S0, S1),
  355    substitute('%f', OsFile, S1, S),
  356    \+ substitute('%d', 1, S, _),
  357    !,
  358    atom_codes(Command, S).
  359external_edit_command(Location, Command) :-
  360    #{file:File} :< Location,
  361    editor(Editor),
  362    format(string(Command), '"~w" "~w"', [Editor, File]).
  363
  364pceemacs(pce_emacs).
  365pceemacs(built_in).
  366
  367%!  editor(-Editor)
  368%
  369%   Determine the external editor to run.
  370
  371editor(Editor) :-                       % $EDITOR
  372    current_prolog_flag(editor, Editor),
  373    (   sub_atom(Editor, 0, _, _, $)
  374    ->  sub_atom(Editor, 1, _, 0, Var),
  375        catch(getenv(Var, Editor), _, fail), !
  376    ;   Editor == default
  377    ->  catch(getenv('EDITOR', Editor), _, fail), !
  378    ;   \+ pceemacs(Editor)
  379    ->  !
  380    ).
  381editor(Editor) :-                       % User defaults
  382    getenv('EDITOR', Editor),
  383    !.
  384editor(vi) :-                           % Platform defaults
  385    current_prolog_flag(unix, true),
  386    !.
  387editor(notepad) :-
  388    current_prolog_flag(windows, true),
  389    !.
  390editor(_) :-                            % No luck
  391    throw(error(existence_error(editor), _)).
  392
  393%!  edit_command(+Editor, -Command)
  394%
  395%   This predicate should specify the shell-command called to invoke
  396%   the user's editor. The following substitutions will be made:
  397%
  398%           | %e | Path name of the editor            |
  399%           | %f | Path name of the file to be edited |
  400%           | %d | Line number of the target          |
  401
  402
  403edit_command(vi,          '%e +%d \'%f\'').
  404edit_command(vi,          '%e \'%f\'').
  405edit_command(emacs,       '%e +%d \'%f\'').
  406edit_command(emacs,       '%e \'%f\'').
  407edit_command(notepad,     '"%e" "%f"').
  408edit_command(wordpad,     '"%e" "%f"').
  409edit_command(uedit32,     '%e "%f/%d/0"').      % ultraedit (www.ultraedit.com)
  410edit_command(jedit,       '%e -wait \'%f\' +line:%d').
  411edit_command(jedit,       '%e -wait \'%f\'').
  412edit_command(edit,        '%e %f:%d').          % PceEmacs client script
  413edit_command(edit,        '%e %f').
  414
  415edit_command(emacsclient, Command) :- edit_command(emacs, Command).
  416edit_command(vim,         Command) :- edit_command(vi,    Command).
  417edit_command(nvim,        Command) :- edit_command(vi,    Command).
  418
  419substitute(FromAtom, ToAtom, Old, New) :-
  420    atom_codes(FromAtom, From),
  421    (   atom(ToAtom)
  422    ->  atom_codes(ToAtom, To)
  423    ;   number_codes(ToAtom, To)
  424    ),
  425    append(Pre, S0, Old),
  426    append(From, Post, S0) ->
  427    append(Pre, To, S1),
  428    append(S1, Post, New),
  429    !.
  430substitute(_, _, Old, Old).
  431
  432
  433                 /*******************************
  434                 *            SELECT            *
  435                 *******************************/
  436
  437merge_locations([L1|T1], Locations) :-
  438    L1 = Loc1-Spec1,
  439    select(L2, T1, T2),
  440    L2 = Loc2-Spec2,
  441    same_location(Loc1, Loc2, Loc),
  442    merge_specs(Spec1, Spec2, Spec),
  443    !,
  444    merge_locations([Loc-Spec|T2], Locations).
  445merge_locations(Locations, Locations).
  446
  447same_location(L, L, L).
  448same_location(#{file:F1}, #{file:F2}, #{file:F}) :-
  449    best_same_file(F1, F2, F).
  450same_location(#{file:F1, line:Line}, #{file:F2}, #{file:F, line:Line}) :-
  451    best_same_file(F1, F2, F).
  452same_location(#{file:F1}, #{file:F2, line:Line}, #{file:F, line:Line}) :-
  453    best_same_file(F1, F2, F).
  454
  455best_same_file(F1, F2, F) :-
  456    catch(same_file(F1, F2), _, fail),
  457    !,
  458    atom_length(F1, L1),
  459    atom_length(F2, L2),
  460    (   L1 < L2
  461    ->  F = F1
  462    ;   F = F2
  463    ).
  464
  465merge_specs(Spec, Spec, Spec) :-
  466    !.
  467merge_specs(file(F1), file(F2), file(F)) :-
  468    best_same_file(F1, F2, F),
  469    !.
  470merge_specs(Spec1, Spec2, Spec) :-
  471    merge_specs_(Spec1, Spec2, Spec),
  472    !.
  473merge_specs(Spec1, Spec2, Spec) :-
  474    merge_specs_(Spec2, Spec1, Spec),
  475    !.
  476
  477merge_specs_(FileSpec, Spec, Spec) :-
  478    is_filespec(FileSpec).
  479
  480is_filespec(source_file(_)) => true.
  481is_filespec(Term),
  482    compound(Term),
  483    compound_name_arguments(Term, Alias, [_Arg]),
  484    user:file_search_path(Alias, _) => true.
  485is_filespec(_) =>
  486    fail.
  487
  488%!  select_location(+Pairs, +UserSpec, -Location) is semidet.
  489%
  490%   @arg Pairs is a list of `Location-Spec` pairs
  491%   @arg Location is a list of properties
  492
  493do_select_location(Pairs, Spec, Location) :-
  494    select_location(Pairs, Spec, Location),                % HOOK
  495    !,
  496    Location \== [].
  497do_select_location([], Spec, _) :-
  498    !,
  499    print_message(warning, edit(not_found(Spec))),
  500    fail.
  501do_select_location([#{file:File}-file(File)], _, Location) :-
  502    !,
  503    Location = #{file:File}.
  504do_select_location([Location-_Spec], _, Location) :-
  505    existing_location(Location),
  506    !.
  507do_select_location(Pairs, _, Location) :-
  508    foldl(number_location, Pairs, NPairs, 1, End),
  509    print_message(help, edit(select(NPairs))),
  510    (   End == 1
  511    ->  fail
  512    ;   Max is End - 1,
  513        user_selection(Max, I),
  514        memberchk(I-(Location-_Spec), NPairs)
  515    ).
  516
  517%!  existing_location(+Location) is semidet.
  518%
  519%   True when Location can be edited.  By   default  that means that the
  520%   file exists. This facility is hooked   to allow for alternative ways
  521%   to reach the source, e.g., by lazily downloading it.
  522
  523existing_location(Location) :-
  524    exists_location(Location),
  525    !.
  526existing_location(Location) :-
  527    #{file:File} :< Location,
  528    access_file(File, read).
  529
  530number_location(Pair, N-Pair, N, N1) :-
  531    Pair = Location-_Spec,
  532    existing_location(Location),
  533    !,
  534    N1 is N+1.
  535number_location(Pair, 0-Pair, N, N).
  536
  537user_selection(Max, I) :-
  538    user_select(Max, I),
  539    !.
  540user_selection(Max, I) :-
  541    print_message(help, edit(choose(Max))),
  542    read_number(Max, I).
  543
  544%!  read_number(+Max, -X) is semidet.
  545%
  546%   Read a number between 1 and Max. If Max < 10, use get_single_char/1.
  547
  548read_number(Max, X) :-
  549    Max < 10,
  550    !,
  551    get_single_char(C),
  552    put_code(user_error, C),
  553    between(0'0, 0'9, C),
  554    X is C - 0'0.
  555read_number(_, X) :-
  556    read_line_to_string(user_input, String),
  557    number_string(X, String).
  558
  559
  560                 /*******************************
  561                 *             MESSAGES         *
  562                 *******************************/
  563
  564:- multifile
  565    prolog:message/3.  566
  567prolog:message(edit(Msg)) -->
  568    message(Msg).
  569
  570message(not_found(Spec)) -->
  571    [ 'Cannot find anything to edit from "~p"'-[Spec] ],
  572    (   { atom(Spec) }
  573    ->  [ nl, '    Use edit(file(~q)) to create a new file'-[Spec] ]
  574    ;   []
  575    ).
  576message(select(NPairs)) -->
  577    { \+ (member(N-_, NPairs), N > 0) },
  578    !,
  579    [ 'Found the following locations:', nl ],
  580    sequence(target, [nl], NPairs).
  581message(select(NPairs)) -->
  582    [ 'Please select item to edit:', nl ],
  583    sequence(target, [nl], NPairs).
  584message(choose(_Max)) -->
  585    [ nl, 'Your choice? ', flush ].
  586message(waiting_for_editor) -->
  587    [ 'Waiting for editor ... ', flush ].
  588message(make) -->
  589    [ 'Running make to reload modified files' ].
  590message(canceled) -->
  591    [ 'Editor returned failure; skipped make/0 to reload files' ].
  592
  593target(0-(Location-Spec)) ==>
  594    [ ansi(warning, '~t*~3| ', [])],
  595    edit_specifier(Spec),
  596    [ '~t~32|' ],
  597    edit_location(Location, false),
  598    [ ansi(warning, ' (no source available)', [])].
  599target(N-(Location-Spec)) ==>
  600    [ ansi(bold, '~t~d~3| ', [N])],
  601    edit_specifier(Spec),
  602    [ '~t~32|' ],
  603    edit_location(Location, true).
  604
  605edit_specifier(Module:Name/Arity) ==>
  606    [ '~w:'-[Module],
  607      ansi(code, '~w/~w', [Name, Arity]) ].
  608edit_specifier(file(_Path)) ==>
  609    [ '<file>' ].
  610edit_specifier(source_file(_Path)) ==>
  611    [ '<loaded file>' ].
  612edit_specifier(include_file(_Path)) ==>
  613    [ '<included file>' ].
  614edit_specifier(Term) ==>
  615    [ '~p'-[Term] ].
  616
  617edit_location(Location, false) ==>
  618    { location_label(Location, Label) },
  619    [ ansi(warning, '~s', [Label]) ].
  620edit_location(Location, true) ==>
  621    { location_label(Location, Label),
  622      location_url(Location, URL)
  623    },
  624    [ url(URL, Label) ].
  625
  626location_label(Location, Label) :-
  627    #{file:File, line:Line} :< Location,
  628    !,
  629    short_filename(File, ShortFile),
  630    format(string(Label), '~w:~d', [ShortFile, Line]).
  631location_label(Location, Label) :-
  632    #{file:File} :< Location,
  633    !,
  634    short_filename(File, ShortFile),
  635    format(string(Label), '~w', [ShortFile]).
  636
  637location_url(Location, File:Line:LinePos) :-
  638    #{file:File, line:Line, linepos:LinePos} :< Location,
  639    !.
  640location_url(Location, File:Line) :-
  641    #{file:File, line:Line} :< Location,
  642    !.
  643location_url(Location, File) :-
  644    #{file:File} :< Location.
  645
  646%!  short_filename(+Path, -Spec) is det.
  647%
  648%   Spec is a way to refer to the file Path that is shorter. The path is
  649%   shortened by either taking  it  relative   to  the  current  working
  650%   directory or use one of the Prolog path aliases.
  651
  652short_filename(Path, Spec) :-
  653    working_directory(Here, Here),
  654    atom_concat(Here, Local0, Path),
  655    !,
  656    remove_leading_slash(Local0, Spec).
  657short_filename(Path, Spec) :-
  658    findall(LenAlias, aliased_path(Path, LenAlias), Keyed),
  659    keysort(Keyed, [_-Spec|_]).
  660short_filename(Path, Path).
  661
  662aliased_path(Path, Len-Spec) :-
  663    setof(Alias, file_alias_path(Alias), Aliases),
  664    member(Alias, Aliases),
  665    Alias \== autoload,             % confusing and covered by something else
  666    Term =.. [Alias, '.'],
  667    absolute_file_name(Term, Prefix,
  668                       [ file_type(directory),
  669                         file_errors(fail),
  670                         solutions(all)
  671                       ]),
  672    atom_concat(Prefix, Local0, Path),
  673    remove_leading_slash(Local0, Local1),
  674    remove_extension(Local1, Local2),
  675    unquote_segments(Local2, Local),
  676    atom_length(Local2, Len),
  677    Spec =.. [Alias, Local].
  678
  679file_alias_path(Alias) :-
  680    user:file_search_path(Alias, _).
  681
  682remove_leading_slash(Path, Local) :-
  683    atom_concat(/, Local, Path),
  684    !.
  685remove_leading_slash(Path, Path).
  686
  687remove_extension(File0, File) :-
  688    file_name_extension(File, Ext, File0),
  689    user:prolog_file_type(Ext, source),
  690    !.
  691remove_extension(File, File).
  692
  693unquote_segments(File, Segments) :-
  694    split_string(File, "/", "/", SegmentStrings),
  695    maplist(atom_string, SegmentList, SegmentStrings),
  696    maplist(no_quote_needed, SegmentList),
  697    !,
  698    segments(SegmentList, Segments).
  699unquote_segments(File, File).
  700
  701
  702no_quote_needed(A) :-
  703    format(atom(Q), '~q', [A]),
  704    Q == A.
  705
  706segments([Segment], Segment) :-
  707    !.
  708segments(List, A/Segment) :-
  709    append(L1, [Segment], List),
  710    !,
  711    segments(L1, A).
  712
  713
  714                 /*******************************
  715                 *        LOAD EXTENSIONS       *
  716                 *******************************/
  717
  718load_extensions :-
  719    load,
  720    fail.
  721load_extensions.
  722
  723:- load_extensions.