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)  1997-2025, 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(warning_var_tag)) -->
  227    [ 'Deprecated: dict with unbound tag (_{...}).  Mapped to #{...}.' ].
  228iso_message(syntax_error(var_tag)) -->
  229    [ 'Syntax error: dict syntax with unbound tag (_{...}).' ].
  230iso_message(syntax_error(Id)) -->
  231    [ 'Syntax error: ' ],
  232    syntax_error(Id).
  233iso_message(occurs_check(Var, In)) -->
  234    [ '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.

  241permission_error(Action, built_in_procedure, Pred) -->
  242    { user_predicate_indicator(Pred, PI)
  243    },
  244    [ 'No permission to ~w built-in predicate `~p'''-[Action, PI] ],
  245    (   {Action \== export}
  246    ->  [ nl,
  247          'Use :- redefine_system_predicate(+Head) if redefinition is intended'
  248        ]
  249    ;   []
  250    ).
  251permission_error(import_into(Dest), procedure, Pred) -->
  252    [ 'No permission to import ~p into ~w'-[Pred, Dest] ].
  253permission_error(Action, static_procedure, Proc) -->
  254    [ 'No permission to ~w static procedure `~p'''-[Action, Proc] ],
  255    defined_definition('Defined', Proc).
  256permission_error(input, stream, Stream) -->
  257    [ 'No permission to read from output stream `~p'''-[Stream] ].
  258permission_error(output, stream, Stream) -->
  259    [ 'No permission to write to input stream `~p'''-[Stream] ].
  260permission_error(input, text_stream, Stream) -->
  261    [ 'No permission to read bytes from TEXT stream `~p'''-[Stream] ].
  262permission_error(output, text_stream, Stream) -->
  263    [ 'No permission to write bytes to TEXT stream `~p'''-[Stream] ].
  264permission_error(input, binary_stream, Stream) -->
  265    [ 'No permission to read characters from binary stream `~p'''-[Stream] ].
  266permission_error(output, binary_stream, Stream) -->
  267    [ 'No permission to write characters to binary stream `~p'''-[Stream] ].
  268permission_error(open, source_sink, alias(Alias)) -->
  269    [ 'No permission to reuse alias "~p": already taken'-[Alias] ].
  270permission_error(tnot, non_tabled_procedure, Pred) -->
  271    [ 'The argument of tnot/1 is not tabled: ~p'-[Pred] ].
  272permission_error(assert, procedure, Pred) -->
  273    { '$pi_head'(Pred, Head),
  274      predicate_property(Head, ssu)
  275    },
  276    [ '~p: an SSU (Head => Body) predicate cannot have normal Prolog clauses'-
  277      [Pred] ].
  278permission_error(Action, Type, Object) -->
  279    [ 'No permission to ~w ~w `~p'''-[Action, Type, Object] ].
  280
  281
  282unknown_proc_msg(_:(^)/2) -->
  283    !,
  284    unknown_proc_msg((^)/2).
  285unknown_proc_msg((^)/2) -->
  286    !,
  287    [nl, '  ^/2 can only appear as the 2nd argument of setof/3 and bagof/3'].
  288unknown_proc_msg((:-)/2) -->
  289    !,
  290    [nl, '  Rules must be loaded from a file'],
  291    faq('ToplevelMode').
  292unknown_proc_msg((=>)/2) -->
  293    !,
  294    [nl, '  Rules must be loaded from a file'],
  295    faq('ToplevelMode').
  296unknown_proc_msg((:-)/1) -->
  297    !,
  298    [nl, '  Directives must be loaded from a file'],
  299    faq('ToplevelMode').
  300unknown_proc_msg((?-)/1) -->
  301    !,
  302    [nl, '  ?- is the Prolog prompt'],
  303    faq('ToplevelMode').
  304unknown_proc_msg(Proc) -->
  305    { dwim_predicates(Proc, Dwims) },
  306    (   {Dwims \== []}
  307    ->  [nl, '  However, there are definitions for:', nl],
  308        dwim_message(Dwims)
  309    ;   []
  310    ).
  311
  312dependency_error(shared(Shared), private(Private)) -->
  313    [ 'Shared table for ~p may not depend on private ~p'-[Shared, Private] ].
  314dependency_error(Dep, monotonic(On)) -->
  315    { '$pi_head'(PI, Dep),
  316      '$pi_head'(MPI, On)
  317    },
  318    [ 'Dependent ~p on monotonic predicate ~p is not monotonic or incremental'-
  319      [PI, MPI]
  320    ].
  321
  322faq(Page) -->
  323    [nl, '  See FAQ at https://www.swi-prolog.org/FAQ/', Page, '.html' ].
  324
  325type_error_comment(_Expected, Actual) -->
  326    { type_of(Actual, Type),
  327      (   sub_atom(Type, 0, 1, _, First),
  328          memberchk(First, [a,e,i,o,u])
  329      ->  Article = an
  330      ;   Article = a
  331      )
  332    },
  333    [ ' (~w ~w)'-[Article, Type] ].
  334
  335type_of(Term, Type) :-
  336    (   attvar(Term)      -> Type = attvar
  337    ;   var(Term)         -> Type = var
  338    ;   atom(Term)        -> Type = atom
  339    ;   integer(Term)     -> Type = integer
  340    ;   string(Term)      -> Type = string
  341    ;   Term == []        -> Type = empty_list
  342    ;   blob(Term, BlobT) -> blob_type(BlobT, Type)
  343    ;   rational(Term)    -> Type = rational
  344    ;   float(Term)       -> Type = float
  345    ;   is_stream(Term)   -> Type = stream
  346    ;   is_dict(Term)     -> Type = dict
  347    ;   is_list(Term)     -> Type = list
  348    ;   cyclic_term(Term) -> Type = cyclic
  349    ;   compound(Term)    -> Type = compound
  350    ;                        Type = unknown
  351    ).
  352
  353blob_type(BlobT, Type) :-
  354    atom_concat(BlobT, '_reference', Type).
  355
  356syntax_error(end_of_clause) -->
  357    [ 'Unexpected end of clause' ].
  358syntax_error(end_of_clause_expected) -->
  359    [ 'End of clause expected' ].
  360syntax_error(end_of_file) -->
  361    [ 'Unexpected end of file' ].
  362syntax_error(end_of_file_in_block_comment) -->
  363    [ 'End of file in /* ... */ comment' ].
  364syntax_error(end_of_file_in_quoted(Quote)) -->
  365    [ 'End of file in quoted ' ],
  366    quoted_type(Quote).
  367syntax_error(illegal_number) -->
  368    [ 'Illegal number' ].
  369syntax_error(long_atom) -->
  370    [ 'Atom too long (see style_check/1)' ].
  371syntax_error(long_string) -->
  372    [ 'String too long (see style_check/1)' ].
  373syntax_error(operator_clash) -->
  374    [ 'Operator priority clash' ].
  375syntax_error(operator_expected) -->
  376    [ 'Operator expected' ].
  377syntax_error(operator_balance) -->
  378    [ 'Unbalanced operator' ].
  379syntax_error(quoted_punctuation) -->
  380    [ 'Operand expected, unquoted comma or bar found' ].
  381syntax_error(list_rest) -->
  382    [ 'Unexpected comma or bar in rest of list' ].
  383syntax_error(cannot_start_term) -->
  384    [ 'Illegal start of term' ].
  385syntax_error(punct(Punct, End)) -->
  386    [ 'Unexpected `~w\' before `~w\''-[Punct, End] ].
  387syntax_error(undefined_char_escape(C)) -->
  388    [ 'Unknown character escape in quoted atom or string: `\\~w\''-[C] ].
  389syntax_error(void_not_allowed) -->
  390    [ 'Empty argument list "()"' ].
  391syntax_error(Term) -->
  392    { compound(Term),
  393      compound_name_arguments(Term, Syntax, [Text])
  394    }, !,
  395    [ '~w expected, found '-[Syntax], ansi(code, '"~w"', [Text]) ].
  396syntax_error(Message) -->
  397    [ '~w'-[Message] ].
  398
  399quoted_type('\'') --> [atom].
  400quoted_type('\"') --> { current_prolog_flag(double_quotes, Type) }, [Type-[]].
  401quoted_type('\`') --> { current_prolog_flag(back_quotes, Type) }, [Type-[]].
  402
  403domain(range(Low,High)) -->
  404    !,
  405    ['[~q..~q]'-[Low,High] ].
  406domain(Domain) -->
  407    ['`~w\''-[Domain] ].

 tabling_existence_error(+Ball, +Context)//

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

  414tabling_existence_error(Ball, Context) -->
  415    { table_shift_ball(Ball) },
  416    [ 'Tabling dependency error' ],
  417    swi_extra(Context).
  418
  419table_shift_ball(dependency(_Head)).
  420table_shift_ball(dependency(_Skeleton, _Trie, _Mono)).
  421table_shift_ball(call_info(_Skeleton, _Status)).
  422table_shift_ball(call_info(_GenSkeleton, _Skeleton, _Status)).

 dwim_predicates(+PI, -Dwims)

Find related predicate indicators.

  428dwim_predicates(Module:Name/_Arity, Dwims) :-
  429    !,
  430    findall(Dwim, dwim_predicate(Module:Name, Dwim), Dwims).
  431dwim_predicates(Name/_Arity, Dwims) :-
  432    findall(Dwim, dwim_predicate(user:Name, Dwim), Dwims).
  433
  434dwim_message([]) --> [].
  435dwim_message([M:Head|T]) -->
  436    { hidden_module(M),
  437      !,
  438      functor(Head, Name, Arity)
  439    },
  440    [ '        ~q'-[Name/Arity], nl ],
  441    dwim_message(T).
  442dwim_message([Module:Head|T]) -->
  443    !,
  444    { functor(Head, Name, Arity)
  445    },
  446    [ '        ~q'-[Module:Name/Arity], nl],
  447    dwim_message(T).
  448dwim_message([Head|T]) -->
  449    {functor(Head, Name, Arity)},
  450    [ '        ~q'-[Name/Arity], nl],
  451    dwim_message(T).
  452
  453
  454swi_message(io_error(Op, Stream)) -->
  455    [ 'I/O error in ~w on stream ~p'-[Op, Stream] ].
  456swi_message(thread_error(TID, false)) -->
  457    [ 'Thread ~p died due to failure:'-[TID] ].
  458swi_message(thread_error(TID, exception(Error))) -->
  459    [ 'Thread ~p died abnormally:'-[TID], nl ],
  460    translate_message(Error).
  461swi_message(dependency_error(Tabled, DependsOn)) -->
  462    dependency_error(Tabled, DependsOn).
  463swi_message(shell(execute, Cmd)) -->
  464    [ 'Could not execute `~w'''-[Cmd] ].
  465swi_message(shell(signal(Sig), Cmd)) -->
  466    [ 'Caught signal ~d on `~w'''-[Sig, Cmd] ].
  467swi_message(format(Fmt, Args)) -->
  468    [ Fmt-Args ].
  469swi_message(signal(Name, Num)) -->
  470    [ 'Caught signal ~d (~w)'-[Num, Name] ].
  471swi_message(limit_exceeded(Limit, MaxVal)) -->
  472    [ 'Exceeded ~w limit (~w)'-[Limit, MaxVal] ].
  473swi_message(goal_failed(Goal)) -->
  474    [ 'goal unexpectedly failed: ~p'-[Goal] ].
  475swi_message(shared_object(_Action, Message)) --> % Message = dlerror()
  476    [ '~w'-[Message] ].
  477swi_message(system_error(Error)) -->
  478    [ 'error in system call: ~w'-[Error]
  479    ].
  480swi_message(system_error) -->
  481    [ 'error in system call'
  482    ].
  483swi_message(failure_error(Goal)) -->
  484    [ 'Goal failed: ~p'-[Goal] ].
  485swi_message(timeout_error(Op, Stream)) -->
  486    [ 'Timeout in ~w from ~p'-[Op, Stream] ].
  487swi_message(not_implemented(Type, What)) -->
  488    [ '~w `~p\' is not implemented in this version'-[Type, What] ].
  489swi_message(context_error(nodirective, Goal)) -->
  490    { goal_to_predicate_indicator(Goal, PI) },
  491    [ 'Wrong context: ~p can only be used in a directive'-[PI] ].
  492swi_message(context_error(edit, no_default_file)) -->
  493    (   { current_prolog_flag(windows, true) }
  494    ->  [ 'Edit/0 can only be used after opening a \c
  495               Prolog file by double-clicking it' ]
  496    ;   [ 'Edit/0 can only be used with the "-s file" commandline option'
  497        ]
  498    ),
  499    [ nl, 'Use "?- edit(Topic)." or "?- emacs."' ].
  500swi_message(context_error(function, meta_arg(S))) -->
  501    [ 'Functions are not (yet) supported for meta-arguments of type ~q'-[S] ].
  502swi_message(format_argument_type(Fmt, Arg)) -->
  503    [ 'Illegal argument to format sequence ~~~w: ~p'-[Fmt, Arg] ].
  504swi_message(format(Msg)) -->
  505    [ 'Format error: ~w'-[Msg] ].
  506swi_message(conditional_compilation_error(unterminated, File:Line)) -->
  507    [ 'Unterminated conditional compilation from '-[], url(File:Line) ].
  508swi_message(conditional_compilation_error(no_if, What)) -->
  509    [ ':- ~w without :- if'-[What] ].
  510swi_message(duplicate_key(Key)) -->
  511    [ 'Duplicate key: ~p'-[Key] ].
  512swi_message(initialization_error(failed, Goal, File:Line)) -->
  513    !,
  514    [ url(File:Line), ': ~p: false'-[Goal] ].
  515swi_message(initialization_error(Error, Goal, File:Line)) -->
  516    [ url(File:Line), ': ~p '-[Goal] ],
  517    translate_message(Error).
  518swi_message(determinism_error(PI, det, Found, property)) -->
  519    (   { '$pi_head'(user:PI, Head),
  520          predicate_property(Head, det)
  521        }
  522    ->  [ 'Deterministic procedure ~p'-[PI] ]
  523    ;   [ 'Procedure ~p called from a deterministic procedure'-[PI] ]
  524    ),
  525    det_error(Found).
  526swi_message(determinism_error(PI, det, fail, guard)) -->
  527    [ 'Procedure ~p failed after $-guard'-[PI] ].
  528swi_message(determinism_error(PI, det, fail, guard_in_caller)) -->
  529    [ 'Procedure ~p failed after $-guard in caller'-[PI] ].
  530swi_message(determinism_error(Goal, det, fail, goal)) -->
  531    [ 'Goal ~p failed'-[Goal] ].
  532swi_message(determinism_error(Goal, det, nondet, goal)) -->
  533    [ 'Goal ~p succeeded with a choice point'-[Goal] ].
  534swi_message(qlf_format_error(File, Message)) -->
  535    [ '~w: Invalid QLF file: ~w'-[File, Message] ].
  536swi_message(goal_expansion_error(bound, Term)) -->
  537    [ 'Goal expansion bound a variable to ~p'-[Term] ].
  538
  539det_error(nondet) -->
  540    [ ' succeeded with a choicepoint'- [] ].
  541det_error(fail) -->
  542    [ ' failed'- [] ].

 swi_location(+Term)// is det

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

  550:- public swi_location//1.  551swi_location(X) -->
  552    { var(X) },
  553    !.
  554swi_location(Context) -->
  555    { message_lang(Lang) },
  556    prolog:message_location(Lang, Context),
  557    !.
  558swi_location(Context) -->
  559    prolog:message_location(Context),
  560    !.
  561swi_location(context(Caller, _Msg)) -->
  562    { ground(Caller) },
  563    !,
  564    caller(Caller).
  565swi_location(file(Path, Line, -1, _CharNo)) -->
  566    !,
  567    [ url(Path:Line), ': ' ].
  568swi_location(file(Path, Line, LinePos, _CharNo)) -->
  569    [ url(Path:Line:LinePos), ': ' ].
  570swi_location(stream(Stream, Line, LinePos, CharNo)) -->
  571    (   { is_stream(Stream),
  572          stream_property(Stream, file_name(File))
  573        }
  574    ->  swi_location(file(File, Line, LinePos, CharNo))
  575    ;   [ 'Stream ~w:~d:~d '-[Stream, Line, LinePos] ]
  576    ).
  577swi_location(autoload(File:Line)) -->
  578    [ url(File:Line), ': ' ].
  579swi_location(_) -->
  580    [].
  581
  582caller(system:'$record_clause'/3) -->
  583    !,
  584    [].
  585caller(Module:Name/Arity) -->
  586    !,
  587    (   { \+ hidden_module(Module) }
  588    ->  [ '~q:~q/~w: '-[Module, Name, Arity] ]
  589    ;   [ '~q/~w: '-[Name, Arity] ]
  590    ).
  591caller(Name/Arity) -->
  592    [ '~q/~w: '-[Name, Arity] ].
  593caller(Caller) -->
  594    [ '~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.

  605swi_extra(X) -->
  606    { var(X) },
  607    !,
  608    [].
  609swi_extra(Context) -->
  610    { message_lang(Lang) },
  611    prolog:message_context(Lang, Context),
  612    !.
  613swi_extra(Context) -->
  614    prolog:message_context(Context).
  615swi_extra(context(_, Msg)) -->
  616    { nonvar(Msg),
  617      Msg \== ''
  618    },
  619    !,
  620    swi_comment(Msg).
  621swi_extra(string(String, CharPos)) -->
  622    { sub_string(String, 0, CharPos, _, Before),
  623      sub_string(String, CharPos, _, 0, After)
  624    },
  625    [ nl, '~w'-[Before], nl, '** here **', nl, '~w'-[After] ].
  626swi_extra(_) -->
  627    [].
  628
  629swi_comment(already_from(Module)) -->
  630    !,
  631    [ ' (already imported from ~q)'-[Module] ].
  632swi_comment(directory(_Dir)) -->
  633    !,
  634    [ ' (is a directory)' ].
  635swi_comment(not_a_directory(_Dir)) -->
  636    !,
  637    [ ' (is not a directory)' ].
  638swi_comment(Msg) -->
  639    [ ' (~w)'-[Msg] ].
  640
  641
  642thread_context -->
  643    { \+ current_prolog_flag(toplevel_thread, true),
  644      thread_self(Id)
  645    },
  646    !,
  647    ['[Thread ~w] '-[Id]].
  648thread_context -->
  649    [].
  650
  651		 /*******************************
  652		 *        UNWIND MESSAGES	*
  653		 *******************************/
  654
  655unwind_message(Var) -->
  656    { var(Var) }, !,
  657    [ 'Unknown unwind message: ~p'-[Var] ].
  658unwind_message(abort) -->
  659    [ 'Execution Aborted' ].
  660unwind_message(halt(_)) -->
  661    [].
  662unwind_message(thread_exit(Term)) -->
  663    [ 'Invalid thread_exit/1.  Payload: ~p'-[Term] ].
  664unwind_message(Term) -->
  665    [ 'Unknown "unwind" exception: ~p'-[Term] ].
  666
  667
  668                 /*******************************
  669                 *        NORMAL MESSAGES       *
  670                 *******************************/
  671
  672:- dynamic prolog:version_msg/1.  673:- multifile prolog:version_msg/1.  674
  675prolog_message(welcome) -->
  676    [ 'Welcome to SWI-Prolog (' ],
  677    prolog_message(threads),
  678    prolog_message(address_bits),
  679    ['version ' ],
  680    prolog_message(version),
  681    [ ')', nl ],
  682    prolog_message(copyright),
  683    [ nl ],
  684    translate_message(user_versions),
  685    [ nl ],
  686    prolog_message(documentaton),
  687    [ nl, nl ].
  688prolog_message(user_versions) -->
  689    (   { findall(Msg, prolog:version_msg(Msg), Msgs),
  690          Msgs \== []
  691        }
  692    ->  [nl],
  693        user_version_messages(Msgs)
  694    ;   []
  695    ).
  696prolog_message(deprecated(Term)) -->
  697    { nonvar(Term) },
  698    (   { message_lang(Lang) },
  699        prolog:deprecated(Lang, Term)
  700    ->  []
  701    ;   prolog:deprecated(Term)
  702    ->  []
  703    ;   deprecated(Term)
  704    ).
  705prolog_message(unhandled_exception(E)) -->
  706    { nonvar(E) },
  707    [ 'Unhandled exception: ' ],
  708    (   translate_message(E)
  709    ->  []
  710    ;   [ '~p'-[E] ]
  711    ).

 prolog_message(+Term)//

  715prolog_message(initialization_error(_, E, File:Line)) -->
  716    !,
  717    [ url(File:Line),
  718      ': Initialization goal raised exception:', nl
  719    ],
  720    translate_message(E).
  721prolog_message(initialization_error(Goal, E, _)) -->
  722    [ 'Initialization goal ~p raised exception:'-[Goal], nl ],
  723    translate_message(E).
  724prolog_message(initialization_failure(_Goal, File:Line)) -->
  725    !,
  726    [ url(File:Line),
  727      ': Initialization goal failed'-[]
  728    ].
  729prolog_message(initialization_failure(Goal, _)) -->
  730    [ 'Initialization goal failed: ~p'-[Goal]
  731    ].
  732prolog_message(initialization_exception(E)) -->
  733    [ 'Prolog initialisation failed:', nl ],
  734    translate_message(E).
  735prolog_message(init_goal_syntax(Error, Text)) -->
  736    !,
  737    [ '-g ~w: '-[Text] ],
  738    translate_message(Error).
  739prolog_message(init_goal_failed(failed, @(Goal,File:Line))) -->
  740    !,
  741    [ url(File:Line), ': ~p: false'-[Goal] ].
  742prolog_message(init_goal_failed(Error, @(Goal,File:Line))) -->
  743    !,
  744    [ url(File:Line), ': ~p '-[Goal] ],
  745    translate_message(Error).
  746prolog_message(init_goal_failed(failed, Text)) -->
  747    !,
  748    [ '-g ~w: false'-[Text] ].
  749prolog_message(init_goal_failed(Error, Text)) -->
  750    !,
  751    [ '-g ~w: '-[Text] ],
  752    translate_message(Error).
  753prolog_message(goal_failed(Context, Goal)) -->
  754    [ 'Goal (~w) failed: ~p'-[Context, Goal] ].
  755prolog_message(no_current_module(Module)) -->
  756    [ '~w is not a current module (created)'-[Module] ].
  757prolog_message(commandline_arg_type(Flag, Arg)) -->
  758    [ 'Bad argument to commandline option -~w: ~w'-[Flag, Arg] ].
  759prolog_message(missing_feature(Name)) -->
  760    [ 'This version of SWI-Prolog does not support ~w'-[Name] ].
  761prolog_message(singletons(_Term, List)) -->
  762    [ 'Singleton variables: ~w'-[List] ].
  763prolog_message(multitons(_Term, List)) -->
  764    [ 'Singleton-marked variables appearing more than once: ~w'-[List] ].
  765prolog_message(profile_no_cpu_time) -->
  766    [ 'No CPU-time info.  Check the SWI-Prolog manual for details' ].
  767prolog_message(non_ascii(Text, Type)) -->
  768    [ 'Unquoted ~w with non-portable characters: ~w'-[Type, Text] ].
  769prolog_message(io_warning(Stream, Message)) -->
  770    { stream_property(Stream, position(Position)),
  771      !,
  772      stream_position_data(line_count, Position, LineNo),
  773      stream_position_data(line_position, Position, LinePos),
  774      (   stream_property(Stream, file_name(File))
  775      ->  Obj = File
  776      ;   Obj = Stream
  777      )
  778    },
  779    [ '~p:~d:~d: ~w'-[Obj, LineNo, LinePos, Message] ].
  780prolog_message(io_warning(Stream, Message)) -->
  781    [ 'stream ~p: ~w'-[Stream, Message] ].
  782prolog_message(option_usage(pldoc)) -->
  783    [ 'Usage: --pldoc[=port]' ].
  784prolog_message(interrupt(begin)) -->
  785    [ 'Action (h for help) ? ', flush ].
  786prolog_message(interrupt(end)) -->
  787    [ 'continue' ].
  788prolog_message(interrupt(trace)) -->
  789    [ 'continue (trace mode)' ].
  790prolog_message(unknown_in_module_user) -->
  791    [ 'Using a non-error value for unknown in the global module', nl,
  792      'causes most of the development environment to stop working.', nl,
  793      'Please use :- dynamic or limit usage of unknown to a module.', nl,
  794      'See https://www.swi-prolog.org/howto/database.html'
  795    ].
  796prolog_message(untable(PI)) -->
  797    [ 'Reconsult: removed tabling for ~p'-[PI] ].
  798prolog_message(unknown_option(Set, Opt)) -->
  799    [ 'Unknown ~w option: ~p'-[Set, Opt] ].
  800
  801
  802                 /*******************************
  803                 *         LOADING FILES        *
  804                 *******************************/
  805
  806prolog_message(modify_active_procedure(Who, What)) -->
  807    [ '~p: modified active procedure ~p'-[Who, What] ].
  808prolog_message(load_file(failed(user:File))) -->
  809    [ 'Failed to load ~p'-[File] ].
  810prolog_message(load_file(failed(Module:File))) -->
  811    [ 'Failed to load ~p into module ~p'-[File, Module] ].
  812prolog_message(load_file(failed(File))) -->
  813    [ 'Failed to load ~p'-[File] ].
  814prolog_message(mixed_directive(Goal)) -->
  815    [ 'Cannot pre-compile mixed load/call directive: ~p'-[Goal] ].
  816prolog_message(cannot_redefine_comma) -->
  817    [ 'Full stop in clause-body?  Cannot redefine ,/2' ].
  818prolog_message(illegal_autoload_index(Dir, Term)) -->
  819    [ 'Illegal term in INDEX file of directory ~w: ~w'-[Dir, Term] ].
  820prolog_message(redefined_procedure(Type, Proc)) -->
  821    [ 'Redefined ~w procedure ~p'-[Type, Proc] ],
  822    defined_definition('Previously defined', Proc).
  823prolog_message(declare_module(Module, abolish(Predicates))) -->
  824    [ 'Loading module ~w abolished: ~p'-[Module, Predicates] ].
  825prolog_message(import_private(Module, Private)) -->
  826    [ 'import/1: ~p is not exported (still imported into ~q)'-
  827      [Private, Module]
  828    ].
  829prolog_message(ignored_weak_import(Into, From:PI)) -->
  830    [ 'Local definition of ~p overrides weak import from ~q'-
  831      [Into:PI, From]
  832    ].
  833prolog_message(undefined_export(Module, PI)) -->
  834    [ 'Exported procedure ~q:~q is not defined'-[Module, PI] ].
  835prolog_message(no_exported_op(Module, Op)) -->
  836    [ 'Operator ~q:~q is not exported (still defined)'-[Module, Op] ].
  837prolog_message(discontiguous((-)/2,_)) -->
  838    prolog_message(minus_in_identifier).
  839prolog_message(discontiguous(Proc,Current)) -->
  840    [ 'Clauses of ', ansi(code, '~p', [Proc]),
  841      ' are not together in the source-file', nl ],
  842    current_definition(Proc, 'Earlier definition at '),
  843    [ 'Current predicate: ', ansi(code, '~p', [Current]), nl,
  844      'Use ', ansi(code, ':- discontiguous ~p.', [Proc]),
  845      ' to suppress this message'
  846    ].
  847prolog_message(decl_no_effect(Goal)) -->
  848    [ 'Deprecated declaration has no effect: ~p'-[Goal] ].
  849prolog_message(load_file(start(Level, File))) -->
  850    [ '~|~t~*+Loading '-[Level] ],
  851    load_file(File),
  852    [ ' ...' ].
  853prolog_message(include_file(start(Level, File))) -->
  854    [ '~|~t~*+include '-[Level] ],
  855    load_file(File),
  856    [ ' ...' ].
  857prolog_message(include_file(done(Level, File))) -->
  858    [ '~|~t~*+included '-[Level] ],
  859    load_file(File).
  860prolog_message(load_file(done(Level, File, Action, Module, Time, Clauses))) -->
  861    [ '~|~t~*+'-[Level] ],
  862    load_file(File),
  863    [ ' ~w'-[Action] ],
  864    load_module(Module),
  865    [ ' ~2f sec, ~D clauses'-[Time, Clauses] ].
  866prolog_message(dwim_undefined(Goal, Alternatives)) -->
  867    { goal_to_predicate_indicator(Goal, Pred)
  868    },
  869    [ 'Unknown procedure: ~q'-[Pred], nl,
  870      '    However, there are definitions for:', nl
  871    ],
  872    dwim_message(Alternatives).
  873prolog_message(dwim_correct(Into)) -->
  874    [ 'Correct to: ~q? '-[Into], flush ].
  875prolog_message(error(loop_error(Spec), file_search(Used))) -->
  876    [ 'File search: too many levels of indirections on: ~p'-[Spec], nl,
  877      '    Used alias expansions:', nl
  878    ],
  879    used_search(Used).
  880prolog_message(minus_in_identifier) -->
  881    [ 'The "-" character should not be used to separate words in an', nl,
  882      'identifier.  Check the SWI-Prolog FAQ for details.'
  883    ].
  884prolog_message(qlf(removed_after_error(File))) -->
  885    [ 'Removed incomplete QLF file ~w'-[File] ].
  886prolog_message(qlf(recompile(Spec,_Pl,_Qlf,Reason))) -->
  887    [ '~p: recompiling QLF file'-[Spec] ],
  888    qlf_recompile_reason(Reason).
  889prolog_message(qlf(can_not_recompile(Spec,QlfFile,_Reason))) -->
  890    [ '~p: can not recompile "~w" (access denied)'-[Spec, QlfFile], nl,
  891      '\tLoading from source'-[]
  892    ].
  893prolog_message(qlf(system_lib_out_of_date(Spec,QlfFile))) -->
  894    [ '~p: can not recompile "~w" (access denied)'-[Spec, QlfFile], nl,
  895      '\tLoading QlfFile'-[]
  896    ].
  897prolog_message(redefine_module(Module, OldFile, File)) -->
  898    [ 'Module "~q" already loaded from ~w.'-[Module, OldFile], nl,
  899      'Wipe and reload from ~w? '-[File], flush
  900    ].
  901prolog_message(redefine_module_reply) -->
  902    [ 'Please answer y(es), n(o) or a(bort)' ].
  903prolog_message(reloaded_in_module(Absolute, OldContext, LM)) -->
  904    [ '~w was previously loaded in module ~w'-[Absolute, OldContext], nl,
  905      '\tnow it is reloaded into module ~w'-[LM] ].
  906prolog_message(expected_layout(Expected, Pos)) -->
  907    [ 'Layout data: expected ~w, found: ~p'-[Expected, Pos] ].
  908
  909defined_definition(Message, Spec) -->
  910    { strip_module(user:Spec, M, Name/Arity),
  911      functor(Head, Name, Arity),
  912      predicate_property(M:Head, file(File)),
  913      predicate_property(M:Head, line_count(Line))
  914    },
  915    !,
  916    [ nl, '~w at '-[Message], url(File:Line) ].
  917defined_definition(_, _) --> [].
  918
  919used_search([]) -->
  920    [].
  921used_search([Alias=Expanded|T]) -->
  922    [ '        file_search_path(~p, ~p)'-[Alias, Expanded], nl ],
  923    used_search(T).
  924
  925load_file(file(Spec, _Path)) -->
  926    (   {atomic(Spec)}
  927    ->  [ '~w'-[Spec] ]
  928    ;   [ '~p'-[Spec] ]
  929    ).
  930%load_file(file(_, Path)) -->
  931%       [ '~w'-[Path] ].
  932
  933load_module(user) --> !.
  934load_module(system) --> !.
  935load_module(Module) -->
  936    [ ' into ~w'-[Module] ].
  937
  938goal_to_predicate_indicator(Goal, PI) :-
  939    strip_module(Goal, Module, Head),
  940    callable_name_arity(Head, Name, Arity),
  941    user_predicate_indicator(Module:Name/Arity, PI).
  942
  943callable_name_arity(Goal, Name, Arity) :-
  944    compound(Goal),
  945    !,
  946    compound_name_arity(Goal, Name, Arity).
  947callable_name_arity(Goal, Goal, 0) :-
  948    atom(Goal).
  949
  950user_predicate_indicator(Module:PI, PI) :-
  951    hidden_module(Module),
  952    !.
  953user_predicate_indicator(PI, PI).
  954
  955hidden_module(user) :- !.
  956hidden_module(system) :- !.
  957hidden_module(M) :-
  958    sub_atom(M, 0, _, _, $).
  959
  960current_definition(Proc, Prefix) -->
  961    { pi_uhead(Proc, Head),
  962      predicate_property(Head, file(File)),
  963      predicate_property(Head, line_count(Line))
  964    },
  965    [ '~w'-[Prefix], url(File:Line), nl ].
  966current_definition(_, _) --> [].
  967
  968pi_uhead(Module:Name/Arity, Module:Head) :-
  969    !,
  970    atom(Module), atom(Name), integer(Arity),
  971    functor(Head, Name, Arity).
  972pi_uhead(Name/Arity, user:Head) :-
  973    atom(Name), integer(Arity),
  974    functor(Head, Name, Arity).
  975
  976qlf_recompile_reason(old) -->
  977    !,
  978    [ ' (out of date)'-[] ].
  979qlf_recompile_reason(_) -->
  980    [ ' (incompatible with current Prolog version)'-[] ].
  981
  982prolog_message(file_search(cache(Spec, _Cond), Path)) -->
  983    [ 'File search: ~p --> ~p (cache)'-[Spec, Path] ].
  984prolog_message(file_search(found(Spec, Cond), Path)) -->
  985    [ 'File search: ~p --> ~p OK ~p'-[Spec, Path, Cond] ].
  986prolog_message(file_search(tried(Spec, Cond), Path)) -->
  987    [ 'File search: ~p --> ~p NO ~p'-[Spec, Path, Cond] ].
  988
  989                 /*******************************
  990                 *              GC              *
  991                 *******************************/
  992
  993prolog_message(agc(start)) -->
  994    thread_context,
  995    [ 'AGC: ', flush ].
  996prolog_message(agc(done(Collected, Remaining, Time))) -->
  997    [ at_same_line,
  998      'reclaimed ~D atoms in ~3f sec. (remaining: ~D)'-
  999      [Collected, Time, Remaining]
 1000    ].
 1001prolog_message(cgc(start)) -->
 1002    thread_context,
 1003    [ 'CGC: ', flush ].
 1004prolog_message(cgc(done(CollectedClauses, _CollectedBytes,
 1005                        RemainingBytes, Time))) -->
 1006    [ at_same_line,
 1007      'reclaimed ~D clauses in ~3f sec. (pending: ~D bytes)'-
 1008      [CollectedClauses, Time, RemainingBytes]
 1009    ].
 1010
 1011		 /*******************************
 1012		 *        STACK OVERFLOW	*
 1013		 *******************************/
 1014
 1015out_of_stack(Context) -->
 1016    { human_stack_size(Context.localused,   Local),
 1017      human_stack_size(Context.globalused,  Global),
 1018      human_stack_size(Context.trailused,   Trail),
 1019      human_stack_size(Context.stack_limit, Limit),
 1020      LCO is (100*(Context.depth - Context.environments))/Context.depth
 1021    },
 1022    [ 'Stack limit (~s) exceeded'-[Limit], nl,
 1023      '  Stack sizes: local: ~s, global: ~s, trail: ~s'-[Local,Global,Trail], nl,
 1024      '  Stack depth: ~D, last-call: ~0f%, Choice points: ~D'-
 1025         [Context.depth, LCO, Context.choicepoints], nl
 1026    ],
 1027    overflow_reason(Context, Resolve),
 1028    resolve_overflow(Resolve).
 1029
 1030human_stack_size(Size, String) :-
 1031    Size < 100,
 1032    format(string(String), '~dKb', [Size]).
 1033human_stack_size(Size, String) :-
 1034    Size < 100 000,
 1035    Value is Size / 1024,
 1036    format(string(String), '~1fMb', [Value]).
 1037human_stack_size(Size, String) :-
 1038    Value is Size / (1024*1024),
 1039    format(string(String), '~1fGb', [Value]).
 1040
 1041overflow_reason(Context, fix) -->
 1042    show_non_termination(Context),
 1043    !.
 1044overflow_reason(Context, enlarge) -->
 1045    { Stack = Context.get(stack) },
 1046    !,
 1047    [ '  In:'-[], nl ],
 1048    stack(Stack).
 1049overflow_reason(_Context, enlarge) -->
 1050    [ '  Insufficient global stack'-[] ].
 1051
 1052show_non_termination(Context) -->
 1053    (   { Stack = Context.get(cycle) }
 1054    ->  [ '  Probable infinite recursion (cycle):'-[], nl ]
 1055    ;   { Stack = Context.get(non_terminating) }
 1056    ->  [ '  Possible non-terminating recursion:'-[], nl ]
 1057    ),
 1058    stack(Stack).
 1059
 1060stack([]) --> [].
 1061stack([frame(Depth, M:Goal, _)|T]) -->
 1062    [ '    [~D] ~q:'-[Depth, M] ],
 1063    stack_goal(Goal),
 1064    [ nl ],
 1065    stack(T).
 1066
 1067stack_goal(Goal) -->
 1068    { compound(Goal),
 1069      !,
 1070      compound_name_arity(Goal, Name, Arity)
 1071    },
 1072    [ '~q('-[Name] ],
 1073    stack_goal_args(1, Arity, Goal),
 1074    [ ')'-[] ].
 1075stack_goal(Goal) -->
 1076    [ '~q'-[Goal] ].
 1077
 1078stack_goal_args(I, Arity, Goal) -->
 1079    { I =< Arity,
 1080      !,
 1081      arg(I, Goal, A),
 1082      I2 is I + 1
 1083    },
 1084    stack_goal_arg(A),
 1085    (   { I2 =< Arity }
 1086    ->  [ ', '-[] ],
 1087        stack_goal_args(I2, Arity, Goal)
 1088    ;   []
 1089    ).
 1090stack_goal_args(_, _, _) -->
 1091    [].
 1092
 1093stack_goal_arg(A) -->
 1094    { nonvar(A),
 1095      A = [Len|T],
 1096      !
 1097    },
 1098    (   {Len == cyclic_term}
 1099    ->  [ '[cyclic list]'-[] ]
 1100    ;   {T == []}
 1101    ->  [ '[length:~D]'-[Len] ]
 1102    ;   [ '[length:~D|~p]'-[Len, T] ]
 1103    ).
 1104stack_goal_arg(A) -->
 1105    { nonvar(A),
 1106      A = _/_,
 1107      !
 1108    },
 1109    [ '<compound ~p>'-[A] ].
 1110stack_goal_arg(A) -->
 1111    [ '~p'-[A] ].
 1112
 1113resolve_overflow(fix) -->
 1114    [].
 1115resolve_overflow(enlarge) -->
 1116    { current_prolog_flag(stack_limit, LimitBytes),
 1117      NewLimit is LimitBytes * 2
 1118    },
 1119    [ nl,
 1120      'Use the --stack_limit=size[KMG] command line option or'-[], nl,
 1121      '?- set_prolog_flag(stack_limit, ~I). to double the limit.'-[NewLimit]
 1122    ].

 out_of_c_stack

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

 1129out_of_c_stack -->
 1130    { statistics(c_stack, Limit), Limit > 0 },
 1131    !,
 1132    [ 'C-stack limit (~D bytes) exceeded.'-[Limit], nl ],
 1133    resolve_c_stack_overflow(Limit).
 1134out_of_c_stack -->
 1135    { statistics(c_stack, Limit), Limit > 0 },
 1136    [ 'C-stack limit exceeded.'-[Limit], nl ],
 1137    resolve_c_stack_overflow(Limit).
 1138
 1139resolve_c_stack_overflow(_Limit) -->
 1140    { thread_self(main) },
 1141    [ 'Use the shell command ' ], code('~w', 'ulimit -s size'),
 1142    [ ' to enlarge the limit.' ].
 1143resolve_c_stack_overflow(_Limit) -->
 1144    [ 'Use the ' ], code('~w', 'c_stack(KBytes)'),
 1145    [ ' option of '], code(thread_create/3), [' to enlarge the limit.' ].
 1146
 1147
 1148                 /*******************************
 1149                 *        MAKE/AUTOLOAD         *
 1150                 *******************************/
 1151
 1152prolog_message(make(reload(Files))) -->
 1153    { length(Files, N)
 1154    },
 1155    [ 'Make: reloading ~D files'-[N] ].
 1156prolog_message(make(done(_Files))) -->
 1157    [ 'Make: finished' ].
 1158prolog_message(make(library_index(Dir))) -->
 1159    [ 'Updating index for library ~w'-[Dir] ].
 1160prolog_message(autoload(Pred, File)) -->
 1161    thread_context,
 1162    [ 'autoloading ~p from ~w'-[Pred, File] ].
 1163prolog_message(autoload(read_index(Dir))) -->
 1164    [ 'Loading autoload index for ~w'-[Dir] ].
 1165prolog_message(autoload(disabled(Loaded))) -->
 1166    [ 'Disabled autoloading (loaded ~D files)'-[Loaded] ].
 1167prolog_message(autoload(already_defined(PI, From))) -->
 1168    code(PI),
 1169    (   { '$pi_head'(PI, Head),
 1170          predicate_property(Head, built_in)
 1171        }
 1172    ->  [' is a built-in predicate']
 1173    ;   [ ' is already imported from module ' ],
 1174        code(From)
 1175    ).
 1176
 1177swi_message(autoload(Msg)) -->
 1178    [ nl, '  ' ],
 1179    autoload_message(Msg).
 1180
 1181autoload_message(not_exported(PI, Spec, _FullFile, _Exports)) -->
 1182    [ ansi(code, '~w', [Spec]),
 1183      ' does not export ',
 1184      ansi(code, '~p', [PI])
 1185    ].
 1186autoload_message(no_file(Spec)) -->
 1187    [ ansi(code, '~p', [Spec]), ': No such file' ].
 1188
 1189
 1190                 /*******************************
 1191                 *       COMPILER WARNINGS      *
 1192                 *******************************/
 1193
 1194% print warnings about dubious code raised by the compiler.
 1195% TBD: pass in PC to produce exact error locations.
 1196
 1197prolog_message(compiler_warnings(Clause, Warnings0)) -->
 1198    {   print_goal_options(DefOptions),
 1199        (   prolog_load_context(variable_names, VarNames)
 1200        ->  warnings_with_named_vars(Warnings0, VarNames, Warnings),
 1201            Options = [variable_names(VarNames)|DefOptions]
 1202        ;   Options = DefOptions,
 1203            Warnings = Warnings0
 1204        )
 1205    },
 1206    compiler_warnings(Warnings, Clause, Options).
 1207
 1208warnings_with_named_vars([], _, []).
 1209warnings_with_named_vars([H|T0], VarNames, [H|T]) :-
 1210    term_variables(H, Vars),
 1211    '$member'(V1, Vars),
 1212    '$member'(_=V2, VarNames),
 1213    V1 == V2,
 1214    !,
 1215    warnings_with_named_vars(T0, VarNames, T).
 1216warnings_with_named_vars([_|T0], VarNames, T) :-
 1217    warnings_with_named_vars(T0, VarNames, T).
 1218
 1219
 1220compiler_warnings([], _, _) --> [].
 1221compiler_warnings([H|T], Clause, Options) -->
 1222    (   compiler_warning(H, Clause, Options)
 1223    ->  []
 1224    ;   [ 'Unknown compiler warning: ~W'-[H,Options] ]
 1225    ),
 1226    (   {T==[]}
 1227    ->  []
 1228    ;   [nl]
 1229    ),
 1230    compiler_warnings(T, Clause, Options).
 1231
 1232compiler_warning(eq_vv(A,B), _Clause, Options) -->
 1233    (   { A == B }
 1234    ->  [ 'Test is always true: ~W'-[A==B, Options] ]
 1235    ;   [ 'Test is always false: ~W'-[A==B, Options] ]
 1236    ).
 1237compiler_warning(eq_singleton(A,B), _Clause, Options) -->
 1238    [ 'Test is always false: ~W'-[A==B, Options] ].
 1239compiler_warning(neq_vv(A,B), _Clause, Options) -->
 1240    (   { A \== B }
 1241    ->  [ 'Test is always true: ~W'-[A\==B, Options] ]
 1242    ;   [ 'Test is always false: ~W'-[A\==B, Options] ]
 1243    ).
 1244compiler_warning(neq_singleton(A,B), _Clause, Options) -->
 1245    [ 'Test is always true: ~W'-[A\==B, Options] ].
 1246compiler_warning(unify_singleton(A,B), _Clause, Options) -->
 1247    [ 'Unified variable is not used: ~W'-[A=B, Options] ].
 1248compiler_warning(always(Bool, Pred, Arg), _Clause, Options) -->
 1249    { Goal =.. [Pred,Arg] },
 1250    [ 'Test is always ~w: ~W'-[Bool, Goal, Options] ].
 1251compiler_warning(unbalanced_var(V), _Clause, Options) -->
 1252    [ 'Variable not introduced in all branches: ~W'-[V, Options] ].
 1253compiler_warning(branch_singleton(V), _Clause, Options) -->
 1254    [ 'Singleton variable in branch: ~W'-[V, Options] ].
 1255compiler_warning(negation_singleton(V), _Clause, Options) -->
 1256    [ 'Singleton variable in \\+: ~W'-[V, Options] ].
 1257compiler_warning(multiton(V), _Clause, Options) -->
 1258    [ 'Singleton-marked variable appears more than once: ~W'-[V, Options] ].
 1259
 1260print_goal_options(
 1261    [ quoted(true),
 1262      portray(true)
 1263    ]).
 1264
 1265
 1266                 /*******************************
 1267                 *      TOPLEVEL MESSAGES       *
 1268                 *******************************/
 1269
 1270prolog_message(version) -->
 1271    { current_prolog_flag(version_git, Version) },
 1272    !,
 1273    [ '~w'-[Version] ].
 1274prolog_message(version) -->
 1275    { current_prolog_flag(version_data, swi(Major,Minor,Patch,Options))
 1276    },
 1277    (   { memberchk(tag(Tag), Options) }
 1278    ->  [ '~w.~w.~w-~w'-[Major, Minor, Patch, Tag] ]
 1279    ;   [ '~w.~w.~w'-[Major, Minor, Patch] ]
 1280    ).
 1281prolog_message(address_bits) -->
 1282    { current_prolog_flag(address_bits, Bits)
 1283    },
 1284    !,
 1285    [ '~d bits, '-[Bits] ].
 1286prolog_message(threads) -->
 1287    { current_prolog_flag(threads, true)
 1288    },
 1289    !,
 1290    [ 'threaded, ' ].
 1291prolog_message(threads) -->
 1292    [].
 1293prolog_message(copyright) -->
 1294    [ 'SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.', nl,
 1295      'Please run ', ansi(code, '?- license.', []), ' for legal details.'
 1296    ].
 1297prolog_message(documentaton) -->
 1298    [ 'For online help and background, visit ', url('https://www.swi-prolog.org') ],
 1299    (   { exists_source(library(help)) }
 1300    ->  [ nl,
 1301          'For built-in help, use ', ansi(code, '?- help(Topic).', []),
 1302          ' or ', ansi(code, '?- apropos(Word).', [])
 1303        ]
 1304    ;   []
 1305    ).
 1306prolog_message(about) -->
 1307    [ 'SWI-Prolog version (' ],
 1308    prolog_message(threads),
 1309    prolog_message(address_bits),
 1310    ['version ' ],
 1311    prolog_message(version),
 1312    [ ')', nl ],
 1313    prolog_message(copyright).
 1314prolog_message(halt) -->
 1315    [ 'halt' ].
 1316prolog_message(break(begin, Level)) -->
 1317    [ 'Break level ~d'-[Level] ].
 1318prolog_message(break(end, Level)) -->
 1319    [ 'Exit break level ~d'-[Level] ].
 1320prolog_message(var_query(_)) -->
 1321    [ '... 1,000,000 ............ 10,000,000 years later', nl, nl,
 1322      '~t~8|>> 42 << (last release gives the question)'
 1323    ].
 1324prolog_message(close_on_abort(Stream)) -->
 1325    [ 'Abort: closed stream ~p'-[Stream] ].
 1326prolog_message(cancel_halt(Reason)) -->
 1327    [ 'Halt cancelled: ~p'-[Reason] ].
 1328prolog_message(on_error(halt(Status))) -->
 1329    { statistics(errors, Errors),
 1330      statistics(warnings, Warnings)
 1331    },
 1332    [ 'Halting with status ~w due to ~D errors and ~D warnings'-
 1333      [Status, Errors, Warnings] ].
 1334
 1335prolog_message(query(QueryResult)) -->
 1336    query_result(QueryResult).
 1337
 1338query_result(no) -->            % failure
 1339    [ ansi(truth(false), 'false.', []) ],
 1340    extra_line.
 1341query_result(yes(true, [])) -->      % prompt_alternatives_on: groundness
 1342    !,
 1343    [ ansi(truth(true), 'true.', []) ],
 1344    extra_line.
 1345query_result(yes(Delays, Residuals)) -->
 1346    result([], Delays, Residuals),
 1347    extra_line.
 1348query_result(done) -->          % user typed <CR>
 1349    extra_line.
 1350query_result(yes(Bindings, Delays, Residuals)) -->
 1351    result(Bindings, Delays, Residuals),
 1352    prompt(yes, Bindings, Delays, Residuals).
 1353query_result(more(Bindings, Delays, Residuals)) -->
 1354    result(Bindings, Delays, Residuals),
 1355    prompt(more, Bindings, Delays, Residuals).
 1356:- if(current_prolog_flag(emscripten, true)). 1357query_result(help) -->
 1358    [ ansi(bold, '  Possible actions:', []), nl,
 1359      '  ; (n,r,space): redo              | t:       trace&redo'-[], nl,
 1360      '  *:             show choicepoint  | . (c,a): stop'-[], nl,
 1361      '  w:             write             | p:       print'-[], nl,
 1362      '  +:             max_depth*5       | -:       max_depth//5'-[], nl,
 1363      '  h (?):         help'-[],
 1364      nl, nl
 1365    ].
 1366:- else. 1367query_result(help) -->
 1368    [ ansi(bold, '  Possible actions:', []), nl,
 1369      '  ; (n,r,space,TAB): redo              | t:           trace&redo'-[], nl,
 1370      '  *:                 show choicepoint  | . (c,a,RET): stop'-[], nl,
 1371      '  w:                 write             | p:           print'-[], nl,
 1372      '  +:                 max_depth*5       | -:           max_depth//5'-[], nl,
 1373      '  b:                 break             | h (?):       help'-[],
 1374      nl, nl
 1375    ].
 1376:- endif. 1377query_result(action) -->
 1378    [ 'Action? '-[], flush ].
 1379query_result(confirm) -->
 1380    [ 'Please answer \'y\' or \'n\'? '-[], flush ].
 1381query_result(eof) -->
 1382    [ nl ].
 1383query_result(toplevel_open_line) -->
 1384    [].
 1385
 1386prompt(Answer, [], true, []-[]) -->
 1387    !,
 1388    prompt(Answer, empty).
 1389prompt(Answer, _, _, _) -->
 1390    !,
 1391    prompt(Answer, non_empty).
 1392
 1393prompt(yes, empty) -->
 1394    !,
 1395    [ ansi(truth(true), 'true.', []) ],
 1396    extra_line.
 1397prompt(yes, _) -->
 1398    !,
 1399    [ full_stop ],
 1400    extra_line.
 1401prompt(more, empty) -->
 1402    !,
 1403    [ ansi(truth(true), 'true ', []), flush ].
 1404prompt(more, _) -->
 1405    !,
 1406    [ ' '-[], flush ].
 1407
 1408result(Bindings, Delays, Residuals) -->
 1409    { current_prolog_flag(answer_write_options, Options0),
 1410      Options = [partial(true)|Options0],
 1411      GOptions = [priority(999)|Options0]
 1412    },
 1413    wfs_residual_program(Delays, GOptions),
 1414    bindings(Bindings, [priority(699)|Options]),
 1415    (   {Residuals == []-[]}
 1416    ->  bind_delays_sep(Bindings, Delays),
 1417        delays(Delays, GOptions)
 1418    ;   bind_res_sep(Bindings, Residuals),
 1419        residuals(Residuals, GOptions),
 1420        (   {Delays == true}
 1421        ->  []
 1422        ;   [','-[], nl],
 1423            delays(Delays, GOptions)
 1424        )
 1425    ).
 1426
 1427bindings([], _) -->
 1428    [].
 1429bindings([binding(Names,Skel,Subst)|T], Options) -->
 1430    { '$last'(Names, Name) },
 1431    var_names(Names), value(Name, Skel, Subst, Options),
 1432    (   { T \== [] }
 1433    ->  [ ','-[], nl ],
 1434        bindings(T, Options)
 1435    ;   []
 1436    ).
 1437
 1438var_names([Name]) -->
 1439    !,
 1440    [ '~w = '-[Name] ].
 1441var_names([Name1,Name2|T]) -->
 1442    !,
 1443    [ '~w = ~w, '-[Name1, Name2] ],
 1444    var_names([Name2|T]).
 1445
 1446
 1447value(Name, Skel, Subst, Options) -->
 1448    (   { var(Skel), Subst = [Skel=S] }
 1449    ->  { Skel = '$VAR'(Name) },
 1450        [ '~W'-[S, Options] ]
 1451    ;   [ '~W'-[Skel, Options] ],
 1452        substitution(Subst, Options)
 1453    ).
 1454
 1455substitution([], _) --> !.
 1456substitution([N=V|T], Options) -->
 1457    [ ', ', ansi(comment, '% where', []), nl,
 1458      '    ~w = ~W'-[N,V,Options] ],
 1459    substitutions(T, Options).
 1460
 1461substitutions([], _) --> [].
 1462substitutions([N=V|T], Options) -->
 1463    [ ','-[], nl, '    ~w = ~W'-[N,V,Options] ],
 1464    substitutions(T, Options).
 1465
 1466
 1467residuals(Normal-Hidden, Options) -->
 1468    residuals1(Normal, Options),
 1469    bind_res_sep(Normal, Hidden),
 1470    (   {Hidden == []}
 1471    ->  []
 1472    ;   [ansi(comment, '% with pending residual goals', []), nl]
 1473    ),
 1474    residuals1(Hidden, Options).
 1475
 1476residuals1([], _) -->
 1477    [].
 1478residuals1([G|Gs], Options) -->
 1479    (   { Gs \== [] }
 1480    ->  [ '~W,'-[G, Options], nl ],
 1481        residuals1(Gs, Options)
 1482    ;   [ '~W'-[G, Options] ]
 1483    ).
 1484
 1485wfs_residual_program(true, _Options) -->
 1486    !.
 1487wfs_residual_program(Goal, _Options) -->
 1488    { current_prolog_flag(toplevel_list_wfs_residual_program, true),
 1489      '$current_typein_module'(TypeIn),
 1490      (   current_predicate(delays_residual_program/2)
 1491      ->  true
 1492      ;   use_module(library(wfs), [delays_residual_program/2])
 1493      ),
 1494      delays_residual_program(TypeIn:Goal, TypeIn:Program),
 1495      Program \== []
 1496    },
 1497    !,
 1498    [ ansi(comment, '% WFS residual program', []), nl ],
 1499    [ ansi(wfs(residual_program), '~@', ['$messages':list_clauses(Program)]) ].
 1500wfs_residual_program(_, _) --> [].
 1501
 1502delays(true, _Options) -->
 1503    !.
 1504delays(Goal, Options) -->
 1505    { current_prolog_flag(toplevel_list_wfs_residual_program, true)
 1506    },
 1507    !,
 1508    [ ansi(truth(undefined), '~W', [Goal, Options]) ].
 1509delays(_, _Options) -->
 1510    [ ansi(truth(undefined), undefined, []) ].
 1511
 1512:- public list_clauses/1. 1513
 1514list_clauses([]).
 1515list_clauses([H|T]) :-
 1516    (   system_undefined(H)
 1517    ->  true
 1518    ;   portray_clause(user_output, H, [indent(4)])
 1519    ),
 1520    list_clauses(T).
 1521
 1522system_undefined((undefined :- tnot(undefined))).
 1523system_undefined((answer_count_restraint :- tnot(answer_count_restraint))).
 1524system_undefined((radial_restraint :- tnot(radial_restraint))).
 1525
 1526bind_res_sep(_, []) --> !.
 1527bind_res_sep(_, []-[]) --> !.
 1528bind_res_sep([], _) --> !.
 1529bind_res_sep(_, _) --> [','-[], nl].
 1530
 1531bind_delays_sep([], _) --> !.
 1532bind_delays_sep(_, true) --> !.
 1533bind_delays_sep(_, _) --> [','-[], nl].
 1534
 1535extra_line -->
 1536    { current_prolog_flag(toplevel_extra_white_line, true) },
 1537    !,
 1538    ['~N'-[]].
 1539extra_line -->
 1540    [].
 1541
 1542prolog_message(if_tty(Message)) -->
 1543    (   {current_prolog_flag(tty_control, true)}
 1544    ->  [ at_same_line ], list(Message)
 1545    ;   []
 1546    ).
 1547prolog_message(halt(Reason)) -->
 1548    [ '~w: halt'-[Reason] ].
 1549prolog_message(no_action(Char)) -->
 1550    [ 'Unknown action: ~c (h for help)'-[Char], nl ].
 1551
 1552prolog_message(history(help(Show, Help))) -->
 1553    [ 'History Commands:', nl,
 1554      '    !!.              Repeat last query', nl,
 1555      '    !nr.             Repeat query numbered <nr>', nl,
 1556      '    !str.            Repeat last query starting with <str>', nl,
 1557      '    !?str.           Repeat last query holding <str>', nl,
 1558      '    ^old^new.        Substitute <old> into <new> of last query', nl,
 1559      '    !nr^old^new.     Substitute in query numbered <nr>', nl,
 1560      '    !str^old^new.    Substitute in query starting with <str>', nl,
 1561      '    !?str^old^new.   Substitute in query holding <str>', nl,
 1562      '    ~w.~21|Show history list'-[Show], nl,
 1563      '    ~w.~21|Show this list'-[Help], nl, nl
 1564    ].
 1565prolog_message(history(no_event)) -->
 1566    [ '! No such event' ].
 1567prolog_message(history(bad_substitution)) -->
 1568    [ '! Bad substitution' ].
 1569prolog_message(history(expanded(Event))) -->
 1570    [ '~w.'-[Event] ].
 1571prolog_message(history(history(Events))) -->
 1572    history_events(Events).
 1573
 1574history_events([]) -->
 1575    [].
 1576history_events([Nr/Event|T]) -->
 1577    [ '~t~w   ~8|~W~W'-[ Nr,
 1578                         Event, [partial(true)],
 1579                         '.', [partial(true)]
 1580                       ],
 1581      nl
 1582    ],
 1583    history_events(T).