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