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)  1997-2024, University of Amsterdam
    7                              VU University Amsterdam
    8                              CWI, Amsterdam
    9                              SWI-Prolog Solutions b.v.
   10    All rights reserved.
   11
   12    Redistribution and use in source and binary forms, with or without
   13    modification, are permitted provided that the following conditions
   14    are met:
   15
   16    1. Redistributions of source code must retain the above copyright
   17       notice, this list of conditions and the following disclaimer.
   18
   19    2. Redistributions in binary form must reproduce the above copyright
   20       notice, this list of conditions and the following disclaimer in
   21       the documentation and/or other materials provided with the
   22       distribution.
   23
   24    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   25    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   26    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   27    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   28    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   29    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   30    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   31    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   32    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   34    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   35    POSSIBILITY OF SUCH DAMAGE.
   36*/
   37
   38:- module('$messages',
   39          [ print_message/2,            % +Kind, +Term
   40            print_message_lines/3,      % +Stream, +Prefix, +Lines
   41            message_to_string/2         % +Term, -String
   42          ]).   43
   44:- multifile
   45    prolog:message//1,              % entire message
   46    prolog:error_message//1,        % 1-st argument of error term
   47    prolog:message_context//1,      % Context of error messages
   48    prolog:deprecated//1,	    % Deprecated features
   49    prolog:message_location//1,     % (File) location of error messages
   50    prolog:message_line_element/2.  % Extend printing
   51:- '$hide'((
   52    prolog:message//1,
   53    prolog:error_message//1,
   54    prolog:message_context//1,
   55    prolog:deprecated//1,
   56    prolog:message_location//1,
   57    prolog:message_line_element/2)).   58% Lang, Term versions
   59:- multifile
   60    prolog:message//2,              % entire message
   61    prolog:error_message//2,        % 1-st argument of error term
   62    prolog:message_context//2,      % Context of error messages
   63    prolog:message_location//2,	    % (File) location of error messages
   64    prolog:deprecated//2.	    % Deprecated features
   65:- '$hide'((
   66    prolog:message//2,
   67    prolog:error_message//2,
   68    prolog:message_context//2,
   69    prolog:deprecated//2,
   70    prolog:message_location//2)).   71
   72:- discontiguous
   73    prolog_message/3.   74
   75:- public
   76    translate_message//1,           % +Message (deprecated)
   77    prolog:translate_message//1.    % +Message
   78
   79:- create_prolog_flag(message_context, [thread], []).

 translate_message(+Term)// is det

Translate a message Term into message lines. The produced lines is a list of

nl

Emit a newline

Fmt - Args

Emit the result of format(Fmt, Args)

Fmt

Emit the result of format(Fmt)

ansi(Code, Fmt, Args)

Use ansi_format/3 for color output.

flush

Used only as last element of the list. Simply flush the output instead of producing a final newline.

at_same_line

Start the messages at the same line (instead of using ~N)

deprecated

- Use code for message translation should call translate_message//1.

  103prolog:translate_message(Term) -->
  104    translate_message(Term).

 translate_message(+Term)// is det

Translate a message term into message lines. This version may be called from user and library definitions for message translation.

  111translate_message(Term) -->
  112    { nonvar(Term) },
  113    (   { message_lang(Lang) },
  114        prolog:message(Lang, Term)
  115    ;   prolog:message(Term)
  116    ),
  117    !.
  118translate_message(Term) -->
  119    { nonvar(Term) },
  120    translate_message2(Term),
  121    !.
  122translate_message(Term) -->
  123    { nonvar(Term),
  124      Term = error(_, _)
  125    },
  126    [ 'Unknown exception: ~p'-[Term] ].
  127translate_message(Term) -->
  128    [ 'Unknown message: ~p'-[Term] ].
  129
  130translate_message2(Term) -->
  131    prolog_message(Term).
  132translate_message2(error(resource_error(stack), Context)) -->
  133    !,
  134    out_of_stack(Context).
  135translate_message2(error(resource_error(tripwire(Wire, Context)), _)) -->
  136    !,
  137    tripwire_message(Wire, Context).
  138translate_message2(error(existence_error(reset, Ball), SWI)) -->
  139    swi_location(SWI),
  140    tabling_existence_error(Ball, SWI).
  141translate_message2(error(ISO, SWI)) -->
  142    swi_location(SWI),
  143    term_message(ISO),
  144    swi_extra(SWI).
  145translate_message2(unwind(Term)) -->
  146    unwind_message(Term).
  147translate_message2(message_lines(Lines), L, T) :- % deal with old C-warning()
  148    make_message_lines(Lines, L, T).
  149translate_message2(format(Fmt, Args)) -->
  150    [ Fmt-Args ].
  151
  152make_message_lines([], T, T) :- !.
  153make_message_lines([Last],  ['~w'-[Last]|T], T) :- !.
  154make_message_lines([L0|LT], ['~w'-[L0],nl|T0], T) :-
  155    make_message_lines(LT, T0, T).

 term_message(+Term)//

Deal with the formal argument of error(Format, ImplDefined) exception terms. The ImplDefined argument is handled by swi_location//2.

  163:- public term_message//1.  164term_message(Term) -->
  165    {var(Term)},
  166    !,
  167    [ 'Unknown error term: ~p'-[Term] ].
  168term_message(Term) -->
  169    { message_lang(Lang) },
  170    prolog:error_message(Lang, Term),
  171    !.
  172term_message(Term) -->
  173    prolog:error_message(Term),
  174    !.
  175term_message(Term) -->
  176    iso_message(Term).
  177term_message(Term) -->
  178    swi_message(Term).
  179term_message(Term) -->
  180    [ 'Unknown error term: ~p'-[Term] ].
  181
  182iso_message(resource_error(c_stack)) -->
  183    out_of_c_stack.
  184iso_message(resource_error(Missing)) -->
  185    [ 'Not enough resources: ~w'-[Missing] ].
  186iso_message(type_error(evaluable, Actual)) -->
  187    { callable(Actual) },
  188    [ 'Arithmetic: `~p'' is not a function'-[Actual] ].
  189iso_message(type_error(free_of_attvar, Actual)) -->
  190    [ 'Type error: `~W'' contains attributed variables'-
  191      [Actual,[portray(true), attributes(portray)]] ].
  192iso_message(type_error(Expected, Actual)) -->
  193    [ 'Type error: `~w'' expected, found `~p'''-[Expected, Actual] ],
  194    type_error_comment(Expected, Actual).
  195iso_message(domain_error(Domain, Actual)) -->
  196    [ 'Domain error: '-[] ], domain(Domain),
  197    [ ' expected, found `~p'''-[Actual] ].
  198iso_message(instantiation_error) -->
  199    [ 'Arguments are not sufficiently instantiated' ].
  200iso_message(uninstantiation_error(Var)) -->
  201    [ 'Uninstantiated argument expected, found ~p'-[Var] ].
  202iso_message(representation_error(What)) -->
  203    [ 'Cannot represent due to `~w'''-[What] ].
  204iso_message(permission_error(Action, Type, Object)) -->
  205    permission_error(Action, Type, Object).
  206iso_message(evaluation_error(Which)) -->
  207    [ 'Arithmetic: evaluation error: `~p'''-[Which] ].
  208iso_message(existence_error(procedure, Proc)) -->
  209    [ 'Unknown procedure: ~q'-[Proc] ],
  210    unknown_proc_msg(Proc).
  211iso_message(existence_error(answer_variable, Var)) -->
  212    [ '$~w was not bound by a previous query'-[Var] ].
  213iso_message(existence_error(matching_rule, Goal)) -->
  214    [ 'No rule matches ~p'-[Goal] ].
  215iso_message(existence_error(Type, Object)) -->
  216    [ '~w `~p'' does not exist'-[Type, Object] ].
  217iso_message(existence_error(export, PI, module(M))) --> % not ISO
  218    [ 'Module ', ansi(code, '~q', [M]), ' does not export ',
  219      ansi(code, '~q', [PI]) ].
  220iso_message(existence_error(Type, Object, In)) --> % not ISO
  221    [ '~w `~p'' does not exist in ~p'-[Type, Object, In] ].
  222iso_message(busy(Type, Object)) -->
  223    [ '~w `~p'' is busy'-[Type, Object] ].
  224iso_message(syntax_error(swi_backslash_newline)) -->
  225    [ 'Deprecated ... \\<newline><white>*.  Use \\c' ].
  226iso_message(syntax_error(Id)) -->
  227    [ 'Syntax error: ' ],
  228    syntax_error(Id).
  229iso_message(occurs_check(Var, In)) -->
  230    [ 'Cannot unify ~p with ~p: would create an infinite tree'-[Var, In] ].

 permission_error(Action, Type, Object)//

Translate permission errors. Most follow te pattern "No permission to Action Type Object", but some are a bit different.

  237permission_error(Action, built_in_procedure, Pred) -->
  238    { user_predicate_indicator(Pred, PI)
  239    },
  240    [ 'No permission to ~w built-in predicate `~p'''-[Action, PI] ],
  241    (   {Action \== export}
  242    ->  [ nl,
  243          'Use :- redefine_system_predicate(+Head) if redefinition is intended'
  244        ]
  245    ;   []
  246    ).
  247permission_error(import_into(Dest), procedure, Pred) -->
  248    [ 'No permission to import ~p into ~w'-[Pred, Dest] ].
  249permission_error(Action, static_procedure, Proc) -->
  250    [ 'No permission to ~w static procedure `~p'''-[Action, Proc] ],
  251    defined_definition('Defined', Proc).
  252permission_error(input, stream, Stream) -->
  253    [ 'No permission to read from output stream `~p'''-[Stream] ].
  254permission_error(output, stream, Stream) -->
  255    [ 'No permission to write to input stream `~p'''-[Stream] ].
  256permission_error(input, text_stream, Stream) -->
  257    [ 'No permission to read bytes from TEXT stream `~p'''-[Stream] ].
  258permission_error(output, text_stream, Stream) -->
  259    [ 'No permission to write bytes to TEXT stream `~p'''-[Stream] ].
  260permission_error(input, binary_stream, Stream) -->
  261    [ 'No permission to read characters from binary stream `~p'''-[Stream] ].
  262permission_error(output, binary_stream, Stream) -->
  263    [ 'No permission to write characters to binary stream `~p'''-[Stream] ].
  264permission_error(open, source_sink, alias(Alias)) -->
  265    [ 'No permission to reuse alias "~p": already taken'-[Alias] ].
  266permission_error(tnot, non_tabled_procedure, Pred) -->
  267    [ 'The argument of tnot/1 is not tabled: ~p'-[Pred] ].
  268permission_error(assert, procedure, Pred) -->
  269    { '$pi_head'(Pred, Head),
  270      predicate_property(Head, ssu)
  271    },
  272    [ '~p: an SSU (Head => Body) predicate cannot have normal Prolog clauses'-
  273      [Pred] ].
  274permission_error(Action, Type, Object) -->
  275    [ 'No permission to ~w ~w `~p'''-[Action, Type, Object] ].
  276
  277
  278unknown_proc_msg(_:(^)/2) -->
  279    !,
  280    unknown_proc_msg((^)/2).
  281unknown_proc_msg((^)/2) -->
  282    !,
  283    [nl, '  ^/2 can only appear as the 2nd argument of setof/3 and bagof/3'].
  284unknown_proc_msg((:-)/2) -->
  285    !,
  286    [nl, '  Rules must be loaded from a file'],
  287    faq('ToplevelMode').
  288unknown_proc_msg((=>)/2) -->
  289    !,
  290    [nl, '  Rules must be loaded from a file'],
  291    faq('ToplevelMode').
  292unknown_proc_msg((:-)/1) -->
  293    !,
  294    [nl, '  Directives must be loaded from a file'],
  295    faq('ToplevelMode').
  296unknown_proc_msg((?-)/1) -->
  297    !,
  298    [nl, '  ?- is the Prolog prompt'],
  299    faq('ToplevelMode').
  300unknown_proc_msg(Proc) -->
  301    { dwim_predicates(Proc, Dwims) },
  302    (   {Dwims \== []}
  303    ->  [nl, '  However, there are definitions for:', nl],
  304        dwim_message(Dwims)
  305    ;   []
  306    ).
  307
  308dependency_error(shared(Shared), private(Private)) -->
  309    [ 'Shared table for ~p may not depend on private ~p'-[Shared, Private] ].
  310dependency_error(Dep, monotonic(On)) -->
  311    { '$pi_head'(PI, Dep),
  312      '$pi_head'(MPI, On)
  313    },
  314    [ 'Dependent ~p on monotonic predicate ~p is not monotonic or incremental'-
  315      [PI, MPI]
  316    ].
  317
  318faq(Page) -->
  319    [nl, '  See FAQ at https://www.swi-prolog.org/FAQ/', Page, '.html' ].
  320
  321type_error_comment(_Expected, Actual) -->
  322    { type_of(Actual, Type),
  323      (   sub_atom(Type, 0, 1, _, First),
  324          memberchk(First, [a,e,i,o,u])
  325      ->  Article = an
  326      ;   Article = a
  327      )
  328    },
  329    [ ' (~w ~w)'-[Article, Type] ].
  330
  331type_of(Term, Type) :-
  332    (   attvar(Term)      -> Type = attvar
  333    ;   var(Term)         -> Type = var
  334    ;   atom(Term)        -> Type = atom
  335    ;   integer(Term)     -> Type = integer
  336    ;   string(Term)      -> Type = string
  337    ;   Term == []        -> Type = empty_list
  338    ;   blob(Term, BlobT) -> blob_type(BlobT, Type)
  339    ;   rational(Term)    -> Type = rational
  340    ;   float(Term)       -> Type = float
  341    ;   is_stream(Term)   -> Type = stream
  342    ;   is_dict(Term)     -> Type = dict
  343    ;   is_list(Term)     -> Type = list
  344    ;   cyclic_term(Term) -> Type = cyclic
  345    ;   compound(Term)    -> Type = compound
  346    ;                        Type = unknown
  347    ).
  348
  349blob_type(BlobT, Type) :-
  350    atom_concat(BlobT, '_reference', Type).
  351
  352syntax_error(end_of_clause) -->
  353    [ 'Unexpected end of clause' ].
  354syntax_error(end_of_clause_expected) -->
  355    [ 'End of clause expected' ].
  356syntax_error(end_of_file) -->
  357    [ 'Unexpected end of file' ].
  358syntax_error(end_of_file_in_block_comment) -->
  359    [ 'End of file in /* ... */ comment' ].
  360syntax_error(end_of_file_in_quoted(Quote)) -->
  361    [ 'End of file in quoted ' ],
  362    quoted_type(Quote).
  363syntax_error(illegal_number) -->
  364    [ 'Illegal number' ].
  365syntax_error(long_atom) -->
  366    [ 'Atom too long (see style_check/1)' ].
  367syntax_error(long_string) -->
  368    [ 'String too long (see style_check/1)' ].
  369syntax_error(operator_clash) -->
  370    [ 'Operator priority clash' ].
  371syntax_error(operator_expected) -->
  372    [ 'Operator expected' ].
  373syntax_error(operator_balance) -->
  374    [ 'Unbalanced operator' ].
  375syntax_error(quoted_punctuation) -->
  376    [ 'Operand expected, unquoted comma or bar found' ].
  377syntax_error(list_rest) -->
  378    [ 'Unexpected comma or bar in rest of list' ].
  379syntax_error(cannot_start_term) -->
  380    [ 'Illegal start of term' ].
  381syntax_error(punct(Punct, End)) -->
  382    [ 'Unexpected `~w\' before `~w\''-[Punct, End] ].
  383syntax_error(undefined_char_escape(C)) -->
  384    [ 'Unknown character escape in quoted atom or string: `\\~w\''-[C] ].
  385syntax_error(void_not_allowed) -->
  386    [ 'Empty argument list "()"' ].
  387syntax_error(Term) -->
  388    { compound(Term),
  389      compound_name_arguments(Term, Syntax, [Text])
  390    }, !,
  391    [ '~w expected, found '-[Syntax], ansi(code, '"~w"', [Text]) ].
  392syntax_error(Message) -->
  393    [ '~w'-[Message] ].
  394
  395quoted_type('\'') --> [atom].
  396quoted_type('\"') --> { current_prolog_flag(double_quotes, Type) }, [Type-[]].
  397quoted_type('\`') --> { current_prolog_flag(back_quotes, Type) }, [Type-[]].
  398
  399domain(range(Low,High)) -->
  400    !,
  401    ['[~q..~q]'-[Low,High] ].
  402domain(Domain) -->
  403    ['`~w\''-[Domain] ].

 tabling_existence_error(+Ball, +Context)//

Called on invalid shift/1 calls. Track those that result from tabling errors.

  410tabling_existence_error(Ball, Context) -->
  411    { table_shift_ball(Ball) },
  412    [ 'Tabling dependency error' ],
  413    swi_extra(Context).
  414
  415table_shift_ball(dependency(_Head)).
  416table_shift_ball(dependency(_Skeleton, _Trie, _Mono)).
  417table_shift_ball(call_info(_Skeleton, _Status)).
  418table_shift_ball(call_info(_GenSkeleton, _Skeleton, _Status)).

 dwim_predicates(+PI, -Dwims)

Find related predicate indicators.

  424dwim_predicates(Module:Name/_Arity, Dwims) :-
  425    !,
  426    findall(Dwim, dwim_predicate(Module:Name, Dwim), Dwims).
  427dwim_predicates(Name/_Arity, Dwims) :-
  428    findall(Dwim, dwim_predicate(user:Name, Dwim), Dwims).
  429
  430dwim_message([]) --> [].
  431dwim_message([M:Head|T]) -->
  432    { hidden_module(M),
  433      !,
  434      functor(Head, Name, Arity)
  435    },
  436    [ '        ~q'-[Name/Arity], nl ],
  437    dwim_message(T).
  438dwim_message([Module:Head|T]) -->
  439    !,
  440    { functor(Head, Name, Arity)
  441    },
  442    [ '        ~q'-[Module:Name/Arity], nl],
  443    dwim_message(T).
  444dwim_message([Head|T]) -->
  445    {functor(Head, Name, Arity)},
  446    [ '        ~q'-[Name/Arity], nl],
  447    dwim_message(T).
  448
  449
  450swi_message(io_error(Op, Stream)) -->
  451    [ 'I/O error in ~w on stream ~p'-[Op, Stream] ].
  452swi_message(thread_error(TID, false)) -->
  453    [ 'Thread ~p died due to failure:'-[TID] ].
  454swi_message(thread_error(TID, exception(Error))) -->
  455    [ 'Thread ~p died abnormally:'-[TID], nl ],
  456    translate_message(Error).
  457swi_message(dependency_error(Tabled, DependsOn)) -->
  458    dependency_error(Tabled, DependsOn).
  459swi_message(shell(execute, Cmd)) -->
  460    [ 'Could not execute `~w'''-[Cmd] ].
  461swi_message(shell(signal(Sig), Cmd)) -->
  462    [ 'Caught signal ~d on `~w'''-[Sig, Cmd] ].
  463swi_message(format(Fmt, Args)) -->
  464    [ Fmt-Args ].
  465swi_message(signal(Name, Num)) -->
  466    [ 'Caught signal ~d (~w)'-[Num, Name] ].
  467swi_message(limit_exceeded(Limit, MaxVal)) -->
  468    [ 'Exceeded ~w limit (~w)'-[Limit, MaxVal] ].
  469swi_message(goal_failed(Goal)) -->
  470    [ 'goal unexpectedly failed: ~p'-[Goal] ].
  471swi_message(shared_object(_Action, Message)) --> % Message = dlerror()
  472    [ '~w'-[Message] ].
  473swi_message(system_error(Error)) -->
  474    [ 'error in system call: ~w'-[Error]
  475    ].
  476swi_message(system_error) -->
  477    [ 'error in system call'
  478    ].
  479swi_message(failure_error(Goal)) -->
  480    [ 'Goal failed: ~p'-[Goal] ].
  481swi_message(timeout_error(Op, Stream)) -->
  482    [ 'Timeout in ~w from ~p'-[Op, Stream] ].
  483swi_message(not_implemented(Type, What)) -->
  484    [ '~w `~p\' is not implemented in this version'-[Type, What] ].
  485swi_message(context_error(nodirective, Goal)) -->
  486    { goal_to_predicate_indicator(Goal, PI) },
  487    [ 'Wrong context: ~p can only be used in a directive'-[PI] ].
  488swi_message(context_error(edit, no_default_file)) -->
  489    (   { current_prolog_flag(windows, true) }
  490    ->  [ 'Edit/0 can only be used after opening a \c
  491               Prolog file by double-clicking it' ]
  492    ;   [ 'Edit/0 can only be used with the "-s file" commandline option'
  493        ]
  494    ),
  495    [ nl, 'Use "?- edit(Topic)." or "?- emacs."' ].
  496swi_message(context_error(function, meta_arg(S))) -->
  497    [ 'Functions are not (yet) supported for meta-arguments of type ~q'-[S] ].
  498swi_message(format_argument_type(Fmt, Arg)) -->
  499    [ 'Illegal argument to format sequence ~~~w: ~p'-[Fmt, Arg] ].
  500swi_message(format(Msg)) -->
  501    [ 'Format error: ~w'-[Msg] ].
  502swi_message(conditional_compilation_error(unterminated, File:Line)) -->
  503    [ 'Unterminated conditional compilation from '-[], url(File:Line) ].
  504swi_message(conditional_compilation_error(no_if, What)) -->
  505    [ ':- ~w without :- if'-[What] ].
  506swi_message(duplicate_key(Key)) -->
  507    [ 'Duplicate key: ~p'-[Key] ].
  508swi_message(initialization_error(failed, Goal, File:Line)) -->
  509    !,
  510    [ url(File:Line), ': ~p: false'-[Goal] ].
  511swi_message(initialization_error(Error, Goal, File:Line)) -->
  512    [ url(File:Line), ': ~p '-[Goal] ],
  513    translate_message(Error).
  514swi_message(determinism_error(PI, det, Found, property)) -->
  515    (   { '$pi_head'(user:PI, Head),
  516          predicate_property(Head, det)
  517        }
  518    ->  [ 'Deterministic procedure ~p'-[PI] ]
  519    ;   [ 'Procedure ~p called from a deterministic procedure'-[PI] ]
  520    ),
  521    det_error(Found).
  522swi_message(determinism_error(PI, det, fail, guard)) -->
  523    [ 'Procedure ~p failed after $-guard'-[PI] ].
  524swi_message(determinism_error(PI, det, fail, guard_in_caller)) -->
  525    [ 'Procedure ~p failed after $-guard in caller'-[PI] ].
  526swi_message(determinism_error(Goal, det, fail, goal)) -->
  527    [ 'Goal ~p failed'-[Goal] ].
  528swi_message(determinism_error(Goal, det, nondet, goal)) -->
  529    [ 'Goal ~p succeeded with a choice point'-[Goal] ].
  530swi_message(qlf_format_error(File, Message)) -->
  531    [ '~w: Invalid QLF file: ~w'-[File, Message] ].
  532swi_message(goal_expansion_error(bound, Term)) -->
  533    [ 'Goal expansion bound a variable to ~p'-[Term] ].
  534
  535det_error(nondet) -->
  536    [ ' succeeded with a choicepoint'- [] ].
  537det_error(fail) -->
  538    [ ' failed'- [] ].

 swi_location(+Term)// is det

Print location information for error(Formal, ImplDefined) from the ImplDefined term.

  546:- public swi_location//1.  547swi_location(X) -->
  548    { var(X) },
  549    !.
  550swi_location(Context) -->
  551    { message_lang(Lang) },
  552    prolog:message_location(Lang, Context),
  553    !.
  554swi_location(Context) -->
  555    prolog:message_location(Context),
  556    !.
  557swi_location(context(Caller, _Msg)) -->
  558    { ground(Caller) },
  559    !,
  560    caller(Caller).
  561swi_location(file(Path, Line, -1, _CharNo)) -->
  562    !,
  563    [ url(Path:Line), ': ' ].
  564swi_location(file(Path, Line, LinePos, _CharNo)) -->
  565    [ url(Path:Line:LinePos), ': ' ].
  566swi_location(stream(Stream, Line, LinePos, CharNo)) -->
  567    (   { is_stream(Stream),
  568          stream_property(Stream, file_name(File))
  569        }
  570    ->  swi_location(file(File, Line, LinePos, CharNo))
  571    ;   [ 'Stream ~w:~d:~d '-[Stream, Line, LinePos] ]
  572    ).
  573swi_location(autoload(File:Line)) -->
  574    [ url(File:Line), ': ' ].
  575swi_location(_) -->
  576    [].
  577
  578caller(system:'$record_clause'/3) -->
  579    !,
  580    [].
  581caller(Module:Name/Arity) -->
  582    !,
  583    (   { \+ hidden_module(Module) }
  584    ->  [ '~q:~q/~w: '-[Module, Name, Arity] ]
  585    ;   [ '~q/~w: '-[Name, Arity] ]
  586    ).
  587caller(Name/Arity) -->
  588    [ '~q/~w: '-[Name, Arity] ].
  589caller(Caller) -->
  590    [ '~p: '-[Caller] ].

 swi_extra(+Term)// is det

Extract information from the second argument of an error(Formal, ImplDefined) that is printed after the core of the message.

See also

- swi_location//1 uses the same term to insert context before the core of the message.

  601swi_extra(X) -->
  602    { var(X) },
  603    !,
  604    [].
  605swi_extra(Context) -->
  606    { message_lang(Lang) },
  607    prolog:message_context(Lang, Context),
  608    !.
  609swi_extra(Context) -->
  610    prolog:message_context(Context).
  611swi_extra(context(_, Msg)) -->
  612    { nonvar(Msg),
  613      Msg \== ''
  614    },
  615    !,
  616    swi_comment(Msg).
  617swi_extra(string(String, CharPos)) -->
  618    { sub_string(String, 0, CharPos, _, Before),
  619      sub_string(String, CharPos, _, 0, After)
  620    },
  621    [ nl, '~w'-[Before], nl, '** here **', nl, '~w'-[After] ].
  622swi_extra(_) -->
  623    [].
  624
  625swi_comment(already_from(Module)) -->
  626    !,
  627    [ ' (already imported from ~q)'-[Module] ].
  628swi_comment(directory(_Dir)) -->
  629    !,
  630    [ ' (is a directory)' ].
  631swi_comment(not_a_directory(_Dir)) -->
  632    !,
  633    [ ' (is not a directory)' ].
  634swi_comment(Msg) -->
  635    [ ' (~w)'-[Msg] ].
  636
  637
  638thread_context -->
  639    { thread_self(Me), Me \== main, thread_property(Me, id(Id)) },
  640    !,
  641    ['[Thread ~w] '-[Id]].
  642thread_context -->
  643    [].
  644
  645		 /*******************************
  646		 *        UNWIND MESSAGES	*
  647		 *******************************/
  648
  649unwind_message(Var) -->
  650    { var(Var) }, !,
  651    [ 'Unknown unwind message: ~p'-[Var] ].
  652unwind_message(abort) -->
  653    [ 'Execution Aborted' ].
  654unwind_message(halt(_)) -->
  655    [].
  656unwind_message(thread_exit(Term)) -->
  657    [ 'Invalid thread_exit/1.  Payload: ~p'-[Term] ].
  658unwind_message(Term) -->
  659    [ 'Unknown "unwind" exception: ~p'-[Term] ].
  660
  661
  662                 /*******************************
  663                 *        NORMAL MESSAGES       *
  664                 *******************************/
  665
  666prolog_message(welcome) -->
  667    [ 'Welcome to SWI-Prolog (' ],
  668    prolog_message(threads),
  669    prolog_message(address_bits),
  670    ['version ' ],
  671    prolog_message(version),
  672    [ ')', nl ],
  673    prolog_message(copyright),
  674    [ nl ],
  675    translate_message(user_versions),
  676    [ nl ],
  677    prolog_message(documentaton),
  678    [ nl, nl ].
  679prolog_message(user_versions) -->
  680    (   { findall(Msg, prolog:version_msg(Msg), Msgs),
  681          Msgs \== []
  682        }
  683    ->  [nl],
  684        user_version_messages(Msgs)
  685    ;   []
  686    ).
  687prolog_message(deprecated(Term)) -->
  688    { nonvar(Term) },
  689    (   { message_lang(Lang) },
  690        prolog:deprecated(Lang, Term)
  691    ->  []
  692    ;   prolog:deprecated(Term)
  693    ->  []
  694    ;   deprecated(Term)
  695    ).
  696prolog_message(unhandled_exception(E)) -->
  697    { nonvar(E) },
  698    [ 'Unhandled exception: ' ],
  699    (   translate_message(E)
  700    ->  []
  701    ;   [ '~p'-[E] ]
  702    ).

 prolog_message(+Term)//

  706prolog_message(initialization_error(_, E, File:Line)) -->
  707    !,
  708    [ url(File:Line),
  709      ': Initialization goal raised exception:', nl
  710    ],
  711    translate_message(E).
  712prolog_message(initialization_error(Goal, E, _)) -->
  713    [ 'Initialization goal ~p raised exception:'-[Goal], nl ],
  714    translate_message(E).
  715prolog_message(initialization_failure(_Goal, File:Line)) -->
  716    !,
  717    [ url(File:Line),
  718      ': Initialization goal failed'-[]
  719    ].
  720prolog_message(initialization_failure(Goal, _)) -->
  721    [ 'Initialization goal failed: ~p'-[Goal]
  722    ].
  723prolog_message(initialization_exception(E)) -->
  724    [ 'Prolog initialisation failed:', nl ],
  725    translate_message(E).
  726prolog_message(init_goal_syntax(Error, Text)) -->
  727    !,
  728    [ '-g ~w: '-[Text] ],
  729    translate_message(Error).
  730prolog_message(init_goal_failed(failed, @(Goal,File:Line))) -->
  731    !,
  732    [ url(File:Line), ': ~p: false'-[Goal] ].
  733prolog_message(init_goal_failed(Error, @(Goal,File:Line))) -->
  734    !,
  735    [ url(File:Line), ': ~p '-[Goal] ],
  736    translate_message(Error).
  737prolog_message(init_goal_failed(failed, Text)) -->
  738    !,
  739    [ '-g ~w: false'-[Text] ].
  740prolog_message(init_goal_failed(Error, Text)) -->
  741    !,
  742    [ '-g ~w: '-[Text] ],
  743    translate_message(Error).
  744prolog_message(goal_failed(Context, Goal)) -->
  745    [ 'Goal (~w) failed: ~p'-[Context, Goal] ].
  746prolog_message(no_current_module(Module)) -->
  747    [ '~w is not a current module (created)'-[Module] ].
  748prolog_message(commandline_arg_type(Flag, Arg)) -->
  749    [ 'Bad argument to commandline option -~w: ~w'-[Flag, Arg] ].
  750prolog_message(missing_feature(Name)) -->
  751    [ 'This version of SWI-Prolog does not support ~w'-[Name] ].
  752prolog_message(singletons(_Term, List)) -->
  753    [ 'Singleton variables: ~w'-[List] ].
  754prolog_message(multitons(_Term, List)) -->
  755    [ 'Singleton-marked variables appearing more than once: ~w'-[List] ].
  756prolog_message(profile_no_cpu_time) -->
  757    [ 'No CPU-time info.  Check the SWI-Prolog manual for details' ].
  758prolog_message(non_ascii(Text, Type)) -->
  759    [ 'Unquoted ~w with non-portable characters: ~w'-[Type, Text] ].
  760prolog_message(io_warning(Stream, Message)) -->
  761    { stream_property(Stream, position(Position)),
  762      !,
  763      stream_position_data(line_count, Position, LineNo),
  764      stream_position_data(line_position, Position, LinePos),
  765      (   stream_property(Stream, file_name(File))
  766      ->  Obj = File
  767      ;   Obj = Stream
  768      )
  769    },
  770    [ '~p:~d:~d: ~w'-[Obj, LineNo, LinePos, Message] ].
  771prolog_message(io_warning(Stream, Message)) -->
  772    [ 'stream ~p: ~w'-[Stream, Message] ].
  773prolog_message(option_usage(pldoc)) -->
  774    [ 'Usage: --pldoc[=port]' ].
  775prolog_message(interrupt(begin)) -->
  776    [ 'Action (h for help) ? ', flush ].
  777prolog_message(interrupt(end)) -->
  778    [ 'continue' ].
  779prolog_message(interrupt(trace)) -->
  780    [ 'continue (trace mode)' ].
  781prolog_message(unknown_in_module_user) -->
  782    [ 'Using a non-error value for unknown in the global module', nl,
  783      'causes most of the development environment to stop working.', nl,
  784      'Please use :- dynamic or limit usage of unknown to a module.', nl,
  785      'See https://www.swi-prolog.org/howto/database.html'
  786    ].
  787prolog_message(untable(PI)) -->
  788    [ 'Reconsult: removed tabling for ~p'-[PI] ].
  789
  790
  791                 /*******************************
  792                 *         LOADING FILES        *
  793                 *******************************/
  794
  795prolog_message(modify_active_procedure(Who, What)) -->
  796    [ '~p: modified active procedure ~p'-[Who, What] ].
  797prolog_message(load_file(failed(user:File))) -->
  798    [ 'Failed to load ~p'-[File] ].
  799prolog_message(load_file(failed(Module:File))) -->
  800    [ 'Failed to load ~p into module ~p'-[File, Module] ].
  801prolog_message(load_file(failed(File))) -->
  802    [ 'Failed to load ~p'-[File] ].
  803prolog_message(mixed_directive(Goal)) -->
  804    [ 'Cannot pre-compile mixed load/call directive: ~p'-[Goal] ].
  805prolog_message(cannot_redefine_comma) -->
  806    [ 'Full stop in clause-body?  Cannot redefine ,/2' ].
  807prolog_message(illegal_autoload_index(Dir, Term)) -->
  808    [ 'Illegal term in INDEX file of directory ~w: ~w'-[Dir, Term] ].
  809prolog_message(redefined_procedure(Type, Proc)) -->
  810    [ 'Redefined ~w procedure ~p'-[Type, Proc] ],
  811    defined_definition('Previously defined', Proc).
  812prolog_message(declare_module(Module, abolish(Predicates))) -->
  813    [ 'Loading module ~w abolished: ~p'-[Module, Predicates] ].
  814prolog_message(import_private(Module, Private)) -->
  815    [ 'import/1: ~p is not exported (still imported into ~q)'-
  816      [Private, Module]
  817    ].
  818prolog_message(ignored_weak_import(Into, From:PI)) -->
  819    [ 'Local definition of ~p overrides weak import from ~q'-
  820      [Into:PI, From]
  821    ].
  822prolog_message(undefined_export(Module, PI)) -->
  823    [ 'Exported procedure ~q:~q is not defined'-[Module, PI] ].
  824prolog_message(no_exported_op(Module, Op)) -->
  825    [ 'Operator ~q:~q is not exported (still defined)'-[Module, Op] ].
  826prolog_message(discontiguous((-)/2,_)) -->
  827    prolog_message(minus_in_identifier).
  828prolog_message(discontiguous(Proc,Current)) -->
  829    [ 'Clauses of ', ansi(code, '~p', [Proc]),
  830      ' are not together in the source-file', nl ],
  831    current_definition(Proc, 'Earlier definition at '),
  832    [ 'Current predicate: ', ansi(code, '~p', [Current]), nl,
  833      'Use ', ansi(code, ':- discontiguous ~p.', [Proc]),
  834      ' to suppress this message'
  835    ].
  836prolog_message(decl_no_effect(Goal)) -->
  837    [ 'Deprecated declaration has no effect: ~p'-[Goal] ].
  838prolog_message(load_file(start(Level, File))) -->
  839    [ '~|~t~*+Loading '-[Level] ],
  840    load_file(File),
  841    [ ' ...' ].
  842prolog_message(include_file(start(Level, File))) -->
  843    [ '~|~t~*+include '-[Level] ],
  844    load_file(File),
  845    [ ' ...' ].
  846prolog_message(include_file(done(Level, File))) -->
  847    [ '~|~t~*+included '-[Level] ],
  848    load_file(File).
  849prolog_message(load_file(done(Level, File, Action, Module, Time, Clauses))) -->
  850    [ '~|~t~*+'-[Level] ],
  851    load_file(File),
  852    [ ' ~w'-[Action] ],
  853    load_module(Module),
  854    [ ' ~2f sec, ~D clauses'-[Time, Clauses] ].
  855prolog_message(dwim_undefined(Goal, Alternatives)) -->
  856    { goal_to_predicate_indicator(Goal, Pred)
  857    },
  858    [ 'Unknown procedure: ~q'-[Pred], nl,
  859      '    However, there are definitions for:', nl
  860    ],
  861    dwim_message(Alternatives).
  862prolog_message(dwim_correct(Into)) -->
  863    [ 'Correct to: ~q? '-[Into], flush ].
  864prolog_message(error(loop_error(Spec), file_search(Used))) -->
  865    [ 'File search: too many levels of indirections on: ~p'-[Spec], nl,
  866      '    Used alias expansions:', nl
  867    ],
  868    used_search(Used).
  869prolog_message(minus_in_identifier) -->
  870    [ 'The "-" character should not be used to separate words in an', nl,
  871      'identifier.  Check the SWI-Prolog FAQ for details.'
  872    ].
  873prolog_message(qlf(removed_after_error(File))) -->
  874    [ 'Removed incomplete QLF file ~w'-[File] ].
  875prolog_message(qlf(recompile(Spec,_Pl,_Qlf,Reason))) -->
  876    [ '~p: recompiling QLF file'-[Spec] ],
  877    qlf_recompile_reason(Reason).
  878prolog_message(qlf(can_not_recompile(Spec,QlfFile,_Reason))) -->
  879    [ '~p: can not recompile "~w" (access denied)'-[Spec, QlfFile], nl,
  880      '\tLoading from source'-[]
  881    ].
  882prolog_message(qlf(system_lib_out_of_date(Spec,QlfFile))) -->
  883    [ '~p: can not recompile "~w" (access denied)'-[Spec, QlfFile], nl,
  884      '\tLoading QlfFile'-[]
  885    ].
  886prolog_message(redefine_module(Module, OldFile, File)) -->
  887    [ 'Module "~q" already loaded from ~w.'-[Module, OldFile], nl,
  888      'Wipe and reload from ~w? '-[File], flush
  889    ].
  890prolog_message(redefine_module_reply) -->
  891    [ 'Please answer y(es), n(o) or a(bort)' ].
  892prolog_message(reloaded_in_module(Absolute, OldContext, LM)) -->
  893    [ '~w was previously loaded in module ~w'-[Absolute, OldContext], nl,
  894      '\tnow it is reloaded into module ~w'-[LM] ].
  895prolog_message(expected_layout(Expected, Pos)) -->
  896    [ 'Layout data: expected ~w, found: ~p'-[Expected, Pos] ].
  897
  898defined_definition(Message, Spec) -->
  899    { strip_module(user:Spec, M, Name/Arity),
  900      functor(Head, Name, Arity),
  901      predicate_property(M:Head, file(File)),
  902      predicate_property(M:Head, line_count(Line))
  903    },
  904    !,
  905    [ nl, '~w at '-[Message], url(File:Line) ].
  906defined_definition(_, _) --> [].
  907
  908used_search([]) -->
  909    [].
  910used_search([Alias=Expanded|T]) -->
  911    [ '        file_search_path(~p, ~p)'-[Alias, Expanded], nl ],
  912    used_search(T).
  913
  914load_file(file(Spec, _Path)) -->
  915    (   {atomic(Spec)}
  916    ->  [ '~w'-[Spec] ]
  917    ;   [ '~p'-[Spec] ]
  918    ).
  919%load_file(file(_, Path)) -->
  920%       [ '~w'-[Path] ].
  921
  922load_module(user) --> !.
  923load_module(system) --> !.
  924load_module(Module) -->
  925    [ ' into ~w'-[Module] ].
  926
  927goal_to_predicate_indicator(Goal, PI) :-
  928    strip_module(Goal, Module, Head),
  929    callable_name_arity(Head, Name, Arity),
  930    user_predicate_indicator(Module:Name/Arity, PI).
  931
  932callable_name_arity(Goal, Name, Arity) :-
  933    compound(Goal),
  934    !,
  935    compound_name_arity(Goal, Name, Arity).
  936callable_name_arity(Goal, Goal, 0) :-
  937    atom(Goal).
  938
  939user_predicate_indicator(Module:PI, PI) :-
  940    hidden_module(Module),
  941    !.
  942user_predicate_indicator(PI, PI).
  943
  944hidden_module(user) :- !.
  945hidden_module(system) :- !.
  946hidden_module(M) :-
  947    sub_atom(M, 0, _, _, $).
  948
  949current_definition(Proc, Prefix) -->
  950    { pi_uhead(Proc, Head),
  951      predicate_property(Head, file(File)),
  952      predicate_property(Head, line_count(Line))
  953    },
  954    [ '~w'-[Prefix], url(File:Line), nl ].
  955current_definition(_, _) --> [].
  956
  957pi_uhead(Module:Name/Arity, Module:Head) :-
  958    !,
  959    atom(Module), atom(Name), integer(Arity),
  960    functor(Head, Name, Arity).
  961pi_uhead(Name/Arity, user:Head) :-
  962    atom(Name), integer(Arity),
  963    functor(Head, Name, Arity).
  964
  965qlf_recompile_reason(old) -->
  966    !,
  967    [ ' (out of date)'-[] ].
  968qlf_recompile_reason(_) -->
  969    [ ' (incompatible with current Prolog version)'-[] ].
  970
  971prolog_message(file_search(cache(Spec, _Cond), Path)) -->
  972    [ 'File search: ~p --> ~p (cache)'-[Spec, Path] ].
  973prolog_message(file_search(found(Spec, Cond), Path)) -->
  974    [ 'File search: ~p --> ~p OK ~p'-[Spec, Path, Cond] ].
  975prolog_message(file_search(tried(Spec, Cond), Path)) -->
  976    [ 'File search: ~p --> ~p NO ~p'-[Spec, Path, Cond] ].
  977
  978                 /*******************************
  979                 *              GC              *
  980                 *******************************/
  981
  982prolog_message(agc(start)) -->
  983    thread_context,
  984    [ 'AGC: ', flush ].
  985prolog_message(agc(done(Collected, Remaining, Time))) -->
  986    [ at_same_line,
  987      'reclaimed ~D atoms in ~3f sec. (remaining: ~D)'-
  988      [Collected, Time, Remaining]
  989    ].
  990prolog_message(cgc(start)) -->
  991    thread_context,
  992    [ 'CGC: ', flush ].
  993prolog_message(cgc(done(CollectedClauses, _CollectedBytes,
  994                        RemainingBytes, Time))) -->
  995    [ at_same_line,
  996      'reclaimed ~D clauses in ~3f sec. (pending: ~D bytes)'-
  997      [CollectedClauses, Time, RemainingBytes]
  998    ].
  999
 1000		 /*******************************
 1001		 *        STACK OVERFLOW	*
 1002		 *******************************/
 1003
 1004out_of_stack(Context) -->
 1005    { human_stack_size(Context.localused,   Local),
 1006      human_stack_size(Context.globalused,  Global),
 1007      human_stack_size(Context.trailused,   Trail),
 1008      human_stack_size(Context.stack_limit, Limit),
 1009      LCO is (100*(Context.depth - Context.environments))/Context.depth
 1010    },
 1011    [ 'Stack limit (~s) exceeded'-[Limit], nl,
 1012      '  Stack sizes: local: ~s, global: ~s, trail: ~s'-[Local,Global,Trail], nl,
 1013      '  Stack depth: ~D, last-call: ~0f%, Choice points: ~D'-
 1014         [Context.depth, LCO, Context.choicepoints], nl
 1015    ],
 1016    overflow_reason(Context, Resolve),
 1017    resolve_overflow(Resolve).
 1018
 1019human_stack_size(Size, String) :-
 1020    Size < 100,
 1021    format(string(String), '~dKb', [Size]).
 1022human_stack_size(Size, String) :-
 1023    Size < 100 000,
 1024    Value is Size / 1024,
 1025    format(string(String), '~1fMb', [Value]).
 1026human_stack_size(Size, String) :-
 1027    Value is Size / (1024*1024),
 1028    format(string(String), '~1fGb', [Value]).
 1029
 1030overflow_reason(Context, fix) -->
 1031    show_non_termination(Context),
 1032    !.
 1033overflow_reason(Context, enlarge) -->
 1034    { Stack = Context.get(stack) },
 1035    !,
 1036    [ '  In:'-[], nl ],
 1037    stack(Stack).
 1038overflow_reason(_Context, enlarge) -->
 1039    [ '  Insufficient global stack'-[] ].
 1040
 1041show_non_termination(Context) -->
 1042    (   { Stack = Context.get(cycle) }
 1043    ->  [ '  Probable infinite recursion (cycle):'-[], nl ]
 1044    ;   { Stack = Context.get(non_terminating) }
 1045    ->  [ '  Possible non-terminating recursion:'-[], nl ]
 1046    ),
 1047    stack(Stack).
 1048
 1049stack([]) --> [].
 1050stack([frame(Depth, M:Goal, _)|T]) -->
 1051    [ '    [~D] ~q:'-[Depth, M] ],
 1052    stack_goal(Goal),
 1053    [ nl ],
 1054    stack(T).
 1055
 1056stack_goal(Goal) -->
 1057    { compound(Goal),
 1058      !,
 1059      compound_name_arity(Goal, Name, Arity)
 1060    },
 1061    [ '~q('-[Name] ],
 1062    stack_goal_args(1, Arity, Goal),
 1063    [ ')'-[] ].
 1064stack_goal(Goal) -->
 1065    [ '~q'-[Goal] ].
 1066
 1067stack_goal_args(I, Arity, Goal) -->
 1068    { I =< Arity,
 1069      !,
 1070      arg(I, Goal, A),
 1071      I2 is I + 1
 1072    },
 1073    stack_goal_arg(A),
 1074    (   { I2 =< Arity }
 1075    ->  [ ', '-[] ],
 1076        stack_goal_args(I2, Arity, Goal)
 1077    ;   []
 1078    ).
 1079stack_goal_args(_, _, _) -->
 1080    [].
 1081
 1082stack_goal_arg(A) -->
 1083    { nonvar(A),
 1084      A = [Len|T],
 1085      !
 1086    },
 1087    (   {Len == cyclic_term}
 1088    ->  [ '[cyclic list]'-[] ]
 1089    ;   {T == []}
 1090    ->  [ '[length:~D]'-[Len] ]
 1091    ;   [ '[length:~D|~p]'-[Len, T] ]
 1092    ).
 1093stack_goal_arg(A) -->
 1094    { nonvar(A),
 1095      A = _/_,
 1096      !
 1097    },
 1098    [ '<compound ~p>'-[A] ].
 1099stack_goal_arg(A) -->
 1100    [ '~p'-[A] ].
 1101
 1102resolve_overflow(fix) -->
 1103    [].
 1104resolve_overflow(enlarge) -->
 1105    { current_prolog_flag(stack_limit, LimitBytes),
 1106      NewLimit is LimitBytes * 2
 1107    },
 1108    [ nl,
 1109      'Use the --stack_limit=size[KMG] command line option or'-[], nl,
 1110      '?- set_prolog_flag(stack_limit, ~I). to double the limit.'-[NewLimit]
 1111    ].

 out_of_c_stack

The thread's C-stack limit was exceeded. Give some advice on how to resolve this.

 1118out_of_c_stack -->
 1119    { statistics(c_stack, Limit), Limit > 0 },
 1120    !,
 1121    [ 'C-stack limit (~D bytes) exceeded.'-[Limit], nl ],
 1122    resolve_c_stack_overflow(Limit).
 1123out_of_c_stack -->
 1124    { statistics(c_stack, Limit), Limit > 0 },
 1125    [ 'C-stack limit exceeded.'-[Limit], nl ],
 1126    resolve_c_stack_overflow(Limit).
 1127
 1128resolve_c_stack_overflow(_Limit) -->
 1129    { thread_self(main) },
 1130    [ 'Use the shell command ' ], code('~w', 'ulimit -s size'),
 1131    [ ' to enlarge the limit.' ].
 1132resolve_c_stack_overflow(_Limit) -->
 1133    [ 'Use the ' ], code('~w', 'c_stack(KBytes)'),
 1134    [ ' option of '], code(thread_create/3), [' to enlarge the limit.' ].
 1135
 1136
 1137                 /*******************************
 1138                 *        MAKE/AUTOLOAD         *
 1139                 *******************************/
 1140
 1141prolog_message(make(reload(Files))) -->
 1142    { length(Files, N)
 1143    },
 1144    [ 'Make: reloading ~D files'-[N] ].
 1145prolog_message(make(done(_Files))) -->
 1146    [ 'Make: finished' ].
 1147prolog_message(make(library_index(Dir))) -->
 1148    [ 'Updating index for library ~w'-[Dir] ].
 1149prolog_message(autoload(Pred, File)) -->
 1150    thread_context,
 1151    [ 'autoloading ~p from ~w'-[Pred, File] ].
 1152prolog_message(autoload(read_index(Dir))) -->
 1153    [ 'Loading autoload index for ~w'-[Dir] ].
 1154prolog_message(autoload(disabled(Loaded))) -->
 1155    [ 'Disabled autoloading (loaded ~D files)'-[Loaded] ].
 1156prolog_message(autoload(already_defined(PI, From))) -->
 1157    code(PI),
 1158    (   { '$pi_head'(PI, Head),
 1159          predicate_property(Head, built_in)
 1160        }
 1161    ->  [' is a built-in predicate']
 1162    ;   [ ' is already imported from module ' ],
 1163        code(From)
 1164    ).
 1165
 1166swi_message(autoload(Msg)) -->
 1167    [ nl, '  ' ],
 1168    autoload_message(Msg).
 1169
 1170autoload_message(not_exported(PI, Spec, _FullFile, _Exports)) -->
 1171    [ ansi(code, '~w', [Spec]),
 1172      ' does not export ',
 1173      ansi(code, '~p', [PI])
 1174    ].
 1175autoload_message(no_file(Spec)) -->
 1176    [ ansi(code, '~p', [Spec]), ': No such file' ].
 1177
 1178
 1179                 /*******************************
 1180                 *       COMPILER WARNINGS      *
 1181                 *******************************/
 1182
 1183% print warnings about dubious code raised by the compiler.
 1184% TBD: pass in PC to produce exact error locations.
 1185
 1186prolog_message(compiler_warnings(Clause, Warnings0)) -->
 1187    {   print_goal_options(DefOptions),
 1188        (   prolog_load_context(variable_names, VarNames)
 1189        ->  warnings_with_named_vars(Warnings0, VarNames, Warnings),
 1190            Options = [variable_names(VarNames)|DefOptions]
 1191        ;   Options = DefOptions,
 1192            Warnings = Warnings0
 1193        )
 1194    },
 1195    compiler_warnings(Warnings, Clause, Options).
 1196
 1197warnings_with_named_vars([], _, []).
 1198warnings_with_named_vars([H|T0], VarNames, [H|T]) :-
 1199    term_variables(H, Vars),
 1200    '$member'(V1, Vars),
 1201    '$member'(_=V2, VarNames),
 1202    V1 == V2,
 1203    !,
 1204    warnings_with_named_vars(T0, VarNames, T).
 1205warnings_with_named_vars([_|T0], VarNames, T) :-
 1206    warnings_with_named_vars(T0, VarNames, T).
 1207
 1208
 1209compiler_warnings([], _, _) --> [].
 1210compiler_warnings([H|T], Clause, Options) -->
 1211    (   compiler_warning(H, Clause, Options)
 1212    ->  []
 1213    ;   [ 'Unknown compiler warning: ~W'-[H,Options] ]
 1214    ),
 1215    (   {T==[]}
 1216    ->  []
 1217    ;   [nl]
 1218    ),
 1219    compiler_warnings(T, Clause, Options).
 1220
 1221compiler_warning(eq_vv(A,B), _Clause, Options) -->
 1222    (   { A == B }
 1223    ->  [ 'Test is always true: ~W'-[A==B, Options] ]
 1224    ;   [ 'Test is always false: ~W'-[A==B, Options] ]
 1225    ).
 1226compiler_warning(eq_singleton(A,B), _Clause, Options) -->
 1227    [ 'Test is always false: ~W'-[A==B, Options] ].
 1228compiler_warning(neq_vv(A,B), _Clause, Options) -->
 1229    (   { A \== B }
 1230    ->  [ 'Test is always true: ~W'-[A\==B, Options] ]
 1231    ;   [ 'Test is always false: ~W'-[A\==B, Options] ]
 1232    ).
 1233compiler_warning(neq_singleton(A,B), _Clause, Options) -->
 1234    [ 'Test is always true: ~W'-[A\==B, Options] ].
 1235compiler_warning(unify_singleton(A,B), _Clause, Options) -->
 1236    [ 'Unified variable is not used: ~W'-[A=B, Options] ].
 1237compiler_warning(always(Bool, Pred, Arg), _Clause, Options) -->
 1238    { Goal =.. [Pred,Arg] },
 1239    [ 'Test is always ~w: ~W'-[Bool, Goal, Options] ].
 1240compiler_warning(unbalanced_var(V), _Clause, Options) -->
 1241    [ 'Variable not introduced in all branches: ~W'-[V, Options] ].
 1242compiler_warning(branch_singleton(V), _Clause, Options) -->
 1243    [ 'Singleton variable in branch: ~W'-[V, Options] ].
 1244compiler_warning(negation_singleton(V), _Clause, Options) -->
 1245    [ 'Singleton variable in \\+: ~W'-[V, Options] ].
 1246compiler_warning(multiton(V), _Clause, Options) -->
 1247    [ 'Singleton-marked variable appears more than once: ~W'-[V, Options] ].
 1248
 1249print_goal_options(
 1250    [ quoted(true),
 1251      portray(true)
 1252    ]).
 1253
 1254
 1255                 /*******************************
 1256                 *      TOPLEVEL MESSAGES       *
 1257                 *******************************/
 1258
 1259prolog_message(version) -->
 1260    { current_prolog_flag(version_git, Version) },
 1261    !,
 1262    [ '~w'-[Version] ].
 1263prolog_message(version) -->
 1264    { current_prolog_flag(version_data, swi(Major,Minor,Patch,Options))
 1265    },
 1266    (   { memberchk(tag(Tag), Options) }
 1267    ->  [ '~w.~w.~w-~w'-[Major, Minor, Patch, Tag] ]
 1268    ;   [ '~w.~w.~w'-[Major, Minor, Patch] ]
 1269    ).
 1270prolog_message(address_bits) -->
 1271    { current_prolog_flag(address_bits, Bits)
 1272    },
 1273    !,
 1274    [ '~d bits, '-[Bits] ].
 1275prolog_message(threads) -->
 1276    { current_prolog_flag(threads, true)
 1277    },
 1278    !,
 1279    [ 'threaded, ' ].
 1280prolog_message(threads) -->
 1281    [].
 1282prolog_message(copyright) -->
 1283    [ 'SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.', nl,
 1284      'Please run ?- license. for legal details.'
 1285    ].
 1286prolog_message(documentaton) -->
 1287    [ 'For online help and background, visit https://www.swi-prolog.org', nl,
 1288      'For built-in help, use ?- help(Topic). or ?- apropos(Word).'
 1289    ].
 1290prolog_message(about) -->
 1291    [ 'SWI-Prolog version (' ],
 1292    prolog_message(threads),
 1293    prolog_message(address_bits),
 1294    ['version ' ],
 1295    prolog_message(version),
 1296    [ ')', nl ],
 1297    prolog_message(copyright).
 1298prolog_message(halt) -->
 1299    [ 'halt' ].
 1300prolog_message(break(begin, Level)) -->
 1301    [ 'Break level ~d'-[Level] ].
 1302prolog_message(break(end, Level)) -->
 1303    [ 'Exit break level ~d'-[Level] ].
 1304prolog_message(var_query(_)) -->
 1305    [ '... 1,000,000 ............ 10,000,000 years later', nl, nl,
 1306      '~t~8|>> 42 << (last release gives the question)'
 1307    ].
 1308prolog_message(close_on_abort(Stream)) -->
 1309    [ 'Abort: closed stream ~p'-[Stream] ].
 1310prolog_message(cancel_halt(Reason)) -->
 1311    [ 'Halt cancelled: ~p'-[Reason] ].
 1312prolog_message(on_error(halt(Status))) -->
 1313    { statistics(errors, Errors),
 1314      statistics(warnings, Warnings)
 1315    },
 1316    [ 'Halting with status ~w due to ~D errors and ~D warnings'-
 1317      [Status, Errors, Warnings] ].
 1318
 1319prolog_message(query(QueryResult)) -->
 1320    query_result(QueryResult).
 1321
 1322query_result(no) -->            % failure
 1323    [ ansi(truth(false), 'false.', []) ],
 1324    extra_line.
 1325query_result(yes(true, [])) -->      % prompt_alternatives_on: groundness
 1326    !,
 1327    [ ansi(truth(true), 'true.', []) ],
 1328    extra_line.
 1329query_result(yes(Delays, Residuals)) -->
 1330    result([], Delays, Residuals),
 1331    extra_line.
 1332query_result(done) -->          % user typed <CR>
 1333    extra_line.
 1334query_result(yes(Bindings, Delays, Residuals)) -->
 1335    result(Bindings, Delays, Residuals),
 1336    prompt(yes, Bindings, Delays, Residuals).
 1337query_result(more(Bindings, Delays, Residuals)) -->
 1338    result(Bindings, Delays, Residuals),
 1339    prompt(more, Bindings, Delays, Residuals).
 1340query_result(help) -->
 1341    [ ansi(bold, '  Possible actions:', []), nl,
 1342      '  ; (n,r,space,TAB): redo              | t:         trace&redo'-[], nl,
 1343      '  *:                 show choicepoint  | c (a,RET): stop'-[], nl,
 1344      '  w:                 write             | p:         print'-[], nl,
 1345      '  +:                 max_depth*10      | -:         max_depth//10'-[], nl,
 1346      '  b:                 break             | h (?):     help'-[],
 1347      nl, nl
 1348    ].
 1349query_result(action) -->
 1350    [ 'Action? '-[], flush ].
 1351query_result(confirm) -->
 1352    [ 'Please answer \'y\' or \'n\'? '-[], flush ].
 1353query_result(eof) -->
 1354    [ nl ].
 1355query_result(toplevel_open_line) -->
 1356    [].
 1357
 1358prompt(Answer, [], true, []-[]) -->
 1359    !,
 1360    prompt(Answer, empty).
 1361prompt(Answer, _, _, _) -->
 1362    !,
 1363    prompt(Answer, non_empty).
 1364
 1365prompt(yes, empty) -->
 1366    !,
 1367    [ ansi(truth(true), 'true.', []) ],
 1368    extra_line.
 1369prompt(yes, _) -->
 1370    !,
 1371    [ full_stop ],
 1372    extra_line.
 1373prompt(more, empty) -->
 1374    !,
 1375    [ ansi(truth(true), 'true ', []), flush ].
 1376prompt(more, _) -->
 1377    !,
 1378    [ ' '-[], flush ].
 1379
 1380result(Bindings, Delays, Residuals) -->
 1381    { current_prolog_flag(answer_write_options, Options0),
 1382      Options = [partial(true)|Options0],
 1383      GOptions = [priority(999)|Options0]
 1384    },
 1385    wfs_residual_program(Delays, GOptions),
 1386    bindings(Bindings, [priority(699)|Options]),
 1387    (   {Residuals == []-[]}
 1388    ->  bind_delays_sep(Bindings, Delays),
 1389        delays(Delays, GOptions)
 1390    ;   bind_res_sep(Bindings, Residuals),
 1391        residuals(Residuals, GOptions),
 1392        (   {Delays == true}
 1393        ->  []
 1394        ;   [','-[], nl],
 1395            delays(Delays, GOptions)
 1396        )
 1397    ).
 1398
 1399bindings([], _) -->
 1400    [].
 1401bindings([binding(Names,Skel,Subst)|T], Options) -->
 1402    { '$last'(Names, Name) },
 1403    var_names(Names), value(Name, Skel, Subst, Options),
 1404    (   { T \== [] }
 1405    ->  [ ','-[], nl ],
 1406        bindings(T, Options)
 1407    ;   []
 1408    ).
 1409
 1410var_names([Name]) -->
 1411    !,
 1412    [ '~w = '-[Name] ].
 1413var_names([Name1,Name2|T]) -->
 1414    !,
 1415    [ '~w = ~w, '-[Name1, Name2] ],
 1416    var_names([Name2|T]).
 1417
 1418
 1419value(Name, Skel, Subst, Options) -->
 1420    (   { var(Skel), Subst = [Skel=S] }
 1421    ->  { Skel = '$VAR'(Name) },
 1422        [ '~W'-[S, Options] ]
 1423    ;   [ '~W'-[Skel, Options] ],
 1424        substitution(Subst, Options)
 1425    ).
 1426
 1427substitution([], _) --> !.
 1428substitution([N=V|T], Options) -->
 1429    [ ', ', ansi(comment, '% where', []), nl,
 1430      '    ~w = ~W'-[N,V,Options] ],
 1431    substitutions(T, Options).
 1432
 1433substitutions([], _) --> [].
 1434substitutions([N=V|T], Options) -->
 1435    [ ','-[], nl, '    ~w = ~W'-[N,V,Options] ],
 1436    substitutions(T, Options).
 1437
 1438
 1439residuals(Normal-Hidden, Options) -->
 1440    residuals1(Normal, Options),
 1441    bind_res_sep(Normal, Hidden),
 1442    (   {Hidden == []}
 1443    ->  []
 1444    ;   [ansi(comment, '% with pending residual goals', []), nl]
 1445    ),
 1446    residuals1(Hidden, Options).
 1447
 1448residuals1([], _) -->
 1449    [].
 1450residuals1([G|Gs], Options) -->
 1451    (   { Gs \== [] }
 1452    ->  [ '~W,'-[G, Options], nl ],
 1453        residuals1(Gs, Options)
 1454    ;   [ '~W'-[G, Options] ]
 1455    ).
 1456
 1457wfs_residual_program(true, _Options) -->
 1458    !.
 1459wfs_residual_program(Goal, _Options) -->
 1460    { current_prolog_flag(toplevel_list_wfs_residual_program, true),
 1461      '$current_typein_module'(TypeIn),
 1462      (   current_predicate(delays_residual_program/2)
 1463      ->  true
 1464      ;   use_module(library(wfs), [delays_residual_program/2])
 1465      ),
 1466      delays_residual_program(TypeIn:Goal, TypeIn:Program),
 1467      Program \== []
 1468    },
 1469    !,
 1470    [ ansi(comment, '% WFS residual program', []), nl ],
 1471    [ ansi(wfs(residual_program), '~@', ['$messages':list_clauses(Program)]) ].
 1472wfs_residual_program(_, _) --> [].
 1473
 1474delays(true, _Options) -->
 1475    !.
 1476delays(Goal, Options) -->
 1477    { current_prolog_flag(toplevel_list_wfs_residual_program, true)
 1478    },
 1479    !,
 1480    [ ansi(truth(undefined), '~W', [Goal, Options]) ].
 1481delays(_, _Options) -->
 1482    [ ansi(truth(undefined), undefined, []) ].
 1483
 1484:- public list_clauses/1. 1485
 1486list_clauses([]).
 1487list_clauses([H|T]) :-
 1488    (   system_undefined(H)
 1489    ->  true
 1490    ;   portray_clause(user_output, H, [indent(4)])
 1491    ),
 1492    list_clauses(T).
 1493
 1494system_undefined((undefined :- tnot(undefined))).
 1495system_undefined((answer_count_restraint :- tnot(answer_count_restraint))).
 1496system_undefined((radial_restraint :- tnot(radial_restraint))).
 1497
 1498bind_res_sep(_, []) --> !.
 1499bind_res_sep(_, []-[]) --> !.
 1500bind_res_sep([], _) --> !.
 1501bind_res_sep(_, _) --> [','-[], nl].
 1502
 1503bind_delays_sep([], _) --> !.
 1504bind_delays_sep(_, true) --> !.
 1505bind_delays_sep(_, _) --> [','-[], nl].
 1506
 1507extra_line -->
 1508    { current_prolog_flag(toplevel_extra_white_line, true) },
 1509    !,
 1510    ['~N'-[]].
 1511extra_line -->
 1512    [].
 1513
 1514prolog_message(if_tty(Message)) -->
 1515    (   {current_prolog_flag(tty_control, true)}
 1516    ->  [ at_same_line | Message ]
 1517    ;   []
 1518    ).
 1519prolog_message(halt(Reason)) -->
 1520    [ '~w: halt'-[Reason] ].
 1521prolog_message(no_action(Char)) -->
 1522    [ 'Unknown action: ~c (h for help)'-[Char], nl ].
 1523
 1524prolog_message(history(help(Show, Help))) -->
 1525    [ 'History Commands:', nl,
 1526      '    !!.              Repeat last query', nl,
 1527      '    !nr.             Repeat query numbered <nr>', nl,
 1528      '    !str.            Repeat last query starting with <str>', nl,
 1529      '    !?str.           Repeat last query holding <str>', nl,
 1530      '    ^old^new.        Substitute <old> into <new> of last query', nl,
 1531      '    !nr^old^new.     Substitute in query numbered <nr>', nl,
 1532      '    !str^old^new.    Substitute in query starting with <str>', nl,
 1533      '    !?str^old^new.   Substitute in query holding <str>', nl,
 1534      '    ~w.~21|Show history list'-[Show], nl,
 1535      '    ~w.~21|Show this list'-[Help], nl, nl
 1536    ].
 1537prolog_message(history(no_event)) -->
 1538    [ '! No such event' ].
 1539prolog_message(history(bad_substitution)) -->
 1540    [ '! Bad substitution' ].
 1541prolog_message(history(expanded(Event))) -->
 1542    [ '~w.'-[Event] ].
 1543prolog_message(history(history(Events))) -->
 1544    history_events(Events).
 1545
 1546history_events([]) -->
 1547    [].
 1548history_events([Nr/Event|T]) -->
 1549    [ '~t~w   ~8|~W~W'-[ Nr,
 1550                         Event, [partial(true)],
 1551                         '.', [partial(true)]
 1552                       ],
 1553      nl
 1554    ],
 1555    history_events(T).