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(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
  666:- dynamic prolog:version_msg/1.  667:- multifile prolog:version_msg/1.  668
  669prolog_message(welcome) -->
  670    [ 'Welcome to SWI-Prolog (' ],
  671    prolog_message(threads),
  672    prolog_message(address_bits),
  673    ['version ' ],
  674    prolog_message(version),
  675    [ ')', nl ],
  676    prolog_message(copyright),
  677    [ nl ],
  678    translate_message(user_versions),
  679    [ nl ],
  680    prolog_message(documentaton),
  681    [ nl, nl ].
  682prolog_message(user_versions) -->
  683    (   { findall(Msg, prolog:version_msg(Msg), Msgs),
  684          Msgs \== []
  685        }
  686    ->  [nl],
  687        user_version_messages(Msgs)
  688    ;   []
  689    ).
  690prolog_message(deprecated(Term)) -->
  691    { nonvar(Term) },
  692    (   { message_lang(Lang) },
  693        prolog:deprecated(Lang, Term)
  694    ->  []
  695    ;   prolog:deprecated(Term)
  696    ->  []
  697    ;   deprecated(Term)
  698    ).
  699prolog_message(unhandled_exception(E)) -->
  700    { nonvar(E) },
  701    [ 'Unhandled exception: ' ],
  702    (   translate_message(E)
  703    ->  []
  704    ;   [ '~p'-[E] ]
  705    ).

 prolog_message(+Term)//

  709prolog_message(initialization_error(_, E, File:Line)) -->
  710    !,
  711    [ url(File:Line),
  712      ': Initialization goal raised exception:', nl
  713    ],
  714    translate_message(E).
  715prolog_message(initialization_error(Goal, E, _)) -->
  716    [ 'Initialization goal ~p raised exception:'-[Goal], nl ],
  717    translate_message(E).
  718prolog_message(initialization_failure(_Goal, File:Line)) -->
  719    !,
  720    [ url(File:Line),
  721      ': Initialization goal failed'-[]
  722    ].
  723prolog_message(initialization_failure(Goal, _)) -->
  724    [ 'Initialization goal failed: ~p'-[Goal]
  725    ].
  726prolog_message(initialization_exception(E)) -->
  727    [ 'Prolog initialisation failed:', nl ],
  728    translate_message(E).
  729prolog_message(init_goal_syntax(Error, Text)) -->
  730    !,
  731    [ '-g ~w: '-[Text] ],
  732    translate_message(Error).
  733prolog_message(init_goal_failed(failed, @(Goal,File:Line))) -->
  734    !,
  735    [ url(File:Line), ': ~p: false'-[Goal] ].
  736prolog_message(init_goal_failed(Error, @(Goal,File:Line))) -->
  737    !,
  738    [ url(File:Line), ': ~p '-[Goal] ],
  739    translate_message(Error).
  740prolog_message(init_goal_failed(failed, Text)) -->
  741    !,
  742    [ '-g ~w: false'-[Text] ].
  743prolog_message(init_goal_failed(Error, Text)) -->
  744    !,
  745    [ '-g ~w: '-[Text] ],
  746    translate_message(Error).
  747prolog_message(goal_failed(Context, Goal)) -->
  748    [ 'Goal (~w) failed: ~p'-[Context, Goal] ].
  749prolog_message(no_current_module(Module)) -->
  750    [ '~w is not a current module (created)'-[Module] ].
  751prolog_message(commandline_arg_type(Flag, Arg)) -->
  752    [ 'Bad argument to commandline option -~w: ~w'-[Flag, Arg] ].
  753prolog_message(missing_feature(Name)) -->
  754    [ 'This version of SWI-Prolog does not support ~w'-[Name] ].
  755prolog_message(singletons(_Term, List)) -->
  756    [ 'Singleton variables: ~w'-[List] ].
  757prolog_message(multitons(_Term, List)) -->
  758    [ 'Singleton-marked variables appearing more than once: ~w'-[List] ].
  759prolog_message(profile_no_cpu_time) -->
  760    [ 'No CPU-time info.  Check the SWI-Prolog manual for details' ].
  761prolog_message(non_ascii(Text, Type)) -->
  762    [ 'Unquoted ~w with non-portable characters: ~w'-[Type, Text] ].
  763prolog_message(io_warning(Stream, Message)) -->
  764    { stream_property(Stream, position(Position)),
  765      !,
  766      stream_position_data(line_count, Position, LineNo),
  767      stream_position_data(line_position, Position, LinePos),
  768      (   stream_property(Stream, file_name(File))
  769      ->  Obj = File
  770      ;   Obj = Stream
  771      )
  772    },
  773    [ '~p:~d:~d: ~w'-[Obj, LineNo, LinePos, Message] ].
  774prolog_message(io_warning(Stream, Message)) -->
  775    [ 'stream ~p: ~w'-[Stream, Message] ].
  776prolog_message(option_usage(pldoc)) -->
  777    [ 'Usage: --pldoc[=port]' ].
  778prolog_message(interrupt(begin)) -->
  779    [ 'Action (h for help) ? ', flush ].
  780prolog_message(interrupt(end)) -->
  781    [ 'continue' ].
  782prolog_message(interrupt(trace)) -->
  783    [ 'continue (trace mode)' ].
  784prolog_message(unknown_in_module_user) -->
  785    [ 'Using a non-error value for unknown in the global module', nl,
  786      'causes most of the development environment to stop working.', nl,
  787      'Please use :- dynamic or limit usage of unknown to a module.', nl,
  788      'See https://www.swi-prolog.org/howto/database.html'
  789    ].
  790prolog_message(untable(PI)) -->
  791    [ 'Reconsult: removed tabling for ~p'-[PI] ].
  792prolog_message(unknown_option(Set, Opt)) -->
  793    [ 'Unknown ~w option: ~p'-[Set, Opt] ].
  794
  795
  796                 /*******************************
  797                 *         LOADING FILES        *
  798                 *******************************/
  799
  800prolog_message(modify_active_procedure(Who, What)) -->
  801    [ '~p: modified active procedure ~p'-[Who, What] ].
  802prolog_message(load_file(failed(user:File))) -->
  803    [ 'Failed to load ~p'-[File] ].
  804prolog_message(load_file(failed(Module:File))) -->
  805    [ 'Failed to load ~p into module ~p'-[File, Module] ].
  806prolog_message(load_file(failed(File))) -->
  807    [ 'Failed to load ~p'-[File] ].
  808prolog_message(mixed_directive(Goal)) -->
  809    [ 'Cannot pre-compile mixed load/call directive: ~p'-[Goal] ].
  810prolog_message(cannot_redefine_comma) -->
  811    [ 'Full stop in clause-body?  Cannot redefine ,/2' ].
  812prolog_message(illegal_autoload_index(Dir, Term)) -->
  813    [ 'Illegal term in INDEX file of directory ~w: ~w'-[Dir, Term] ].
  814prolog_message(redefined_procedure(Type, Proc)) -->
  815    [ 'Redefined ~w procedure ~p'-[Type, Proc] ],
  816    defined_definition('Previously defined', Proc).
  817prolog_message(declare_module(Module, abolish(Predicates))) -->
  818    [ 'Loading module ~w abolished: ~p'-[Module, Predicates] ].
  819prolog_message(import_private(Module, Private)) -->
  820    [ 'import/1: ~p is not exported (still imported into ~q)'-
  821      [Private, Module]
  822    ].
  823prolog_message(ignored_weak_import(Into, From:PI)) -->
  824    [ 'Local definition of ~p overrides weak import from ~q'-
  825      [Into:PI, From]
  826    ].
  827prolog_message(undefined_export(Module, PI)) -->
  828    [ 'Exported procedure ~q:~q is not defined'-[Module, PI] ].
  829prolog_message(no_exported_op(Module, Op)) -->
  830    [ 'Operator ~q:~q is not exported (still defined)'-[Module, Op] ].
  831prolog_message(discontiguous((-)/2,_)) -->
  832    prolog_message(minus_in_identifier).
  833prolog_message(discontiguous(Proc,Current)) -->
  834    [ 'Clauses of ', ansi(code, '~p', [Proc]),
  835      ' are not together in the source-file', nl ],
  836    current_definition(Proc, 'Earlier definition at '),
  837    [ 'Current predicate: ', ansi(code, '~p', [Current]), nl,
  838      'Use ', ansi(code, ':- discontiguous ~p.', [Proc]),
  839      ' to suppress this message'
  840    ].
  841prolog_message(decl_no_effect(Goal)) -->
  842    [ 'Deprecated declaration has no effect: ~p'-[Goal] ].
  843prolog_message(load_file(start(Level, File))) -->
  844    [ '~|~t~*+Loading '-[Level] ],
  845    load_file(File),
  846    [ ' ...' ].
  847prolog_message(include_file(start(Level, File))) -->
  848    [ '~|~t~*+include '-[Level] ],
  849    load_file(File),
  850    [ ' ...' ].
  851prolog_message(include_file(done(Level, File))) -->
  852    [ '~|~t~*+included '-[Level] ],
  853    load_file(File).
  854prolog_message(load_file(done(Level, File, Action, Module, Time, Clauses))) -->
  855    [ '~|~t~*+'-[Level] ],
  856    load_file(File),
  857    [ ' ~w'-[Action] ],
  858    load_module(Module),
  859    [ ' ~2f sec, ~D clauses'-[Time, Clauses] ].
  860prolog_message(dwim_undefined(Goal, Alternatives)) -->
  861    { goal_to_predicate_indicator(Goal, Pred)
  862    },
  863    [ 'Unknown procedure: ~q'-[Pred], nl,
  864      '    However, there are definitions for:', nl
  865    ],
  866    dwim_message(Alternatives).
  867prolog_message(dwim_correct(Into)) -->
  868    [ 'Correct to: ~q? '-[Into], flush ].
  869prolog_message(error(loop_error(Spec), file_search(Used))) -->
  870    [ 'File search: too many levels of indirections on: ~p'-[Spec], nl,
  871      '    Used alias expansions:', nl
  872    ],
  873    used_search(Used).
  874prolog_message(minus_in_identifier) -->
  875    [ 'The "-" character should not be used to separate words in an', nl,
  876      'identifier.  Check the SWI-Prolog FAQ for details.'
  877    ].
  878prolog_message(qlf(removed_after_error(File))) -->
  879    [ 'Removed incomplete QLF file ~w'-[File] ].
  880prolog_message(qlf(recompile(Spec,_Pl,_Qlf,Reason))) -->
  881    [ '~p: recompiling QLF file'-[Spec] ],
  882    qlf_recompile_reason(Reason).
  883prolog_message(qlf(can_not_recompile(Spec,QlfFile,_Reason))) -->
  884    [ '~p: can not recompile "~w" (access denied)'-[Spec, QlfFile], nl,
  885      '\tLoading from source'-[]
  886    ].
  887prolog_message(qlf(system_lib_out_of_date(Spec,QlfFile))) -->
  888    [ '~p: can not recompile "~w" (access denied)'-[Spec, QlfFile], nl,
  889      '\tLoading QlfFile'-[]
  890    ].
  891prolog_message(redefine_module(Module, OldFile, File)) -->
  892    [ 'Module "~q" already loaded from ~w.'-[Module, OldFile], nl,
  893      'Wipe and reload from ~w? '-[File], flush
  894    ].
  895prolog_message(redefine_module_reply) -->
  896    [ 'Please answer y(es), n(o) or a(bort)' ].
  897prolog_message(reloaded_in_module(Absolute, OldContext, LM)) -->
  898    [ '~w was previously loaded in module ~w'-[Absolute, OldContext], nl,
  899      '\tnow it is reloaded into module ~w'-[LM] ].
  900prolog_message(expected_layout(Expected, Pos)) -->
  901    [ 'Layout data: expected ~w, found: ~p'-[Expected, Pos] ].
  902
  903defined_definition(Message, Spec) -->
  904    { strip_module(user:Spec, M, Name/Arity),
  905      functor(Head, Name, Arity),
  906      predicate_property(M:Head, file(File)),
  907      predicate_property(M:Head, line_count(Line))
  908    },
  909    !,
  910    [ nl, '~w at '-[Message], url(File:Line) ].
  911defined_definition(_, _) --> [].
  912
  913used_search([]) -->
  914    [].
  915used_search([Alias=Expanded|T]) -->
  916    [ '        file_search_path(~p, ~p)'-[Alias, Expanded], nl ],
  917    used_search(T).
  918
  919load_file(file(Spec, _Path)) -->
  920    (   {atomic(Spec)}
  921    ->  [ '~w'-[Spec] ]
  922    ;   [ '~p'-[Spec] ]
  923    ).
  924%load_file(file(_, Path)) -->
  925%       [ '~w'-[Path] ].
  926
  927load_module(user) --> !.
  928load_module(system) --> !.
  929load_module(Module) -->
  930    [ ' into ~w'-[Module] ].
  931
  932goal_to_predicate_indicator(Goal, PI) :-
  933    strip_module(Goal, Module, Head),
  934    callable_name_arity(Head, Name, Arity),
  935    user_predicate_indicator(Module:Name/Arity, PI).
  936
  937callable_name_arity(Goal, Name, Arity) :-
  938    compound(Goal),
  939    !,
  940    compound_name_arity(Goal, Name, Arity).
  941callable_name_arity(Goal, Goal, 0) :-
  942    atom(Goal).
  943
  944user_predicate_indicator(Module:PI, PI) :-
  945    hidden_module(Module),
  946    !.
  947user_predicate_indicator(PI, PI).
  948
  949hidden_module(user) :- !.
  950hidden_module(system) :- !.
  951hidden_module(M) :-
  952    sub_atom(M, 0, _, _, $).
  953
  954current_definition(Proc, Prefix) -->
  955    { pi_uhead(Proc, Head),
  956      predicate_property(Head, file(File)),
  957      predicate_property(Head, line_count(Line))
  958    },
  959    [ '~w'-[Prefix], url(File:Line), nl ].
  960current_definition(_, _) --> [].
  961
  962pi_uhead(Module:Name/Arity, Module:Head) :-
  963    !,
  964    atom(Module), atom(Name), integer(Arity),
  965    functor(Head, Name, Arity).
  966pi_uhead(Name/Arity, user:Head) :-
  967    atom(Name), integer(Arity),
  968    functor(Head, Name, Arity).
  969
  970qlf_recompile_reason(old) -->
  971    !,
  972    [ ' (out of date)'-[] ].
  973qlf_recompile_reason(_) -->
  974    [ ' (incompatible with current Prolog version)'-[] ].
  975
  976prolog_message(file_search(cache(Spec, _Cond), Path)) -->
  977    [ 'File search: ~p --> ~p (cache)'-[Spec, Path] ].
  978prolog_message(file_search(found(Spec, Cond), Path)) -->
  979    [ 'File search: ~p --> ~p OK ~p'-[Spec, Path, Cond] ].
  980prolog_message(file_search(tried(Spec, Cond), Path)) -->
  981    [ 'File search: ~p --> ~p NO ~p'-[Spec, Path, Cond] ].
  982
  983                 /*******************************
  984                 *              GC              *
  985                 *******************************/
  986
  987prolog_message(agc(start)) -->
  988    thread_context,
  989    [ 'AGC: ', flush ].
  990prolog_message(agc(done(Collected, Remaining, Time))) -->
  991    [ at_same_line,
  992      'reclaimed ~D atoms in ~3f sec. (remaining: ~D)'-
  993      [Collected, Time, Remaining]
  994    ].
  995prolog_message(cgc(start)) -->
  996    thread_context,
  997    [ 'CGC: ', flush ].
  998prolog_message(cgc(done(CollectedClauses, _CollectedBytes,
  999                        RemainingBytes, Time))) -->
 1000    [ at_same_line,
 1001      'reclaimed ~D clauses in ~3f sec. (pending: ~D bytes)'-
 1002      [CollectedClauses, Time, RemainingBytes]
 1003    ].
 1004
 1005		 /*******************************
 1006		 *        STACK OVERFLOW	*
 1007		 *******************************/
 1008
 1009out_of_stack(Context) -->
 1010    { human_stack_size(Context.localused,   Local),
 1011      human_stack_size(Context.globalused,  Global),
 1012      human_stack_size(Context.trailused,   Trail),
 1013      human_stack_size(Context.stack_limit, Limit),
 1014      LCO is (100*(Context.depth - Context.environments))/Context.depth
 1015    },
 1016    [ 'Stack limit (~s) exceeded'-[Limit], nl,
 1017      '  Stack sizes: local: ~s, global: ~s, trail: ~s'-[Local,Global,Trail], nl,
 1018      '  Stack depth: ~D, last-call: ~0f%, Choice points: ~D'-
 1019         [Context.depth, LCO, Context.choicepoints], nl
 1020    ],
 1021    overflow_reason(Context, Resolve),
 1022    resolve_overflow(Resolve).
 1023
 1024human_stack_size(Size, String) :-
 1025    Size < 100,
 1026    format(string(String), '~dKb', [Size]).
 1027human_stack_size(Size, String) :-
 1028    Size < 100 000,
 1029    Value is Size / 1024,
 1030    format(string(String), '~1fMb', [Value]).
 1031human_stack_size(Size, String) :-
 1032    Value is Size / (1024*1024),
 1033    format(string(String), '~1fGb', [Value]).
 1034
 1035overflow_reason(Context, fix) -->
 1036    show_non_termination(Context),
 1037    !.
 1038overflow_reason(Context, enlarge) -->
 1039    { Stack = Context.get(stack) },
 1040    !,
 1041    [ '  In:'-[], nl ],
 1042    stack(Stack).
 1043overflow_reason(_Context, enlarge) -->
 1044    [ '  Insufficient global stack'-[] ].
 1045
 1046show_non_termination(Context) -->
 1047    (   { Stack = Context.get(cycle) }
 1048    ->  [ '  Probable infinite recursion (cycle):'-[], nl ]
 1049    ;   { Stack = Context.get(non_terminating) }
 1050    ->  [ '  Possible non-terminating recursion:'-[], nl ]
 1051    ),
 1052    stack(Stack).
 1053
 1054stack([]) --> [].
 1055stack([frame(Depth, M:Goal, _)|T]) -->
 1056    [ '    [~D] ~q:'-[Depth, M] ],
 1057    stack_goal(Goal),
 1058    [ nl ],
 1059    stack(T).
 1060
 1061stack_goal(Goal) -->
 1062    { compound(Goal),
 1063      !,
 1064      compound_name_arity(Goal, Name, Arity)
 1065    },
 1066    [ '~q('-[Name] ],
 1067    stack_goal_args(1, Arity, Goal),
 1068    [ ')'-[] ].
 1069stack_goal(Goal) -->
 1070    [ '~q'-[Goal] ].
 1071
 1072stack_goal_args(I, Arity, Goal) -->
 1073    { I =< Arity,
 1074      !,
 1075      arg(I, Goal, A),
 1076      I2 is I + 1
 1077    },
 1078    stack_goal_arg(A),
 1079    (   { I2 =< Arity }
 1080    ->  [ ', '-[] ],
 1081        stack_goal_args(I2, Arity, Goal)
 1082    ;   []
 1083    ).
 1084stack_goal_args(_, _, _) -->
 1085    [].
 1086
 1087stack_goal_arg(A) -->
 1088    { nonvar(A),
 1089      A = [Len|T],
 1090      !
 1091    },
 1092    (   {Len == cyclic_term}
 1093    ->  [ '[cyclic list]'-[] ]
 1094    ;   {T == []}
 1095    ->  [ '[length:~D]'-[Len] ]
 1096    ;   [ '[length:~D|~p]'-[Len, T] ]
 1097    ).
 1098stack_goal_arg(A) -->
 1099    { nonvar(A),
 1100      A = _/_,
 1101      !
 1102    },
 1103    [ '<compound ~p>'-[A] ].
 1104stack_goal_arg(A) -->
 1105    [ '~p'-[A] ].
 1106
 1107resolve_overflow(fix) -->
 1108    [].
 1109resolve_overflow(enlarge) -->
 1110    { current_prolog_flag(stack_limit, LimitBytes),
 1111      NewLimit is LimitBytes * 2
 1112    },
 1113    [ nl,
 1114      'Use the --stack_limit=size[KMG] command line option or'-[], nl,
 1115      '?- set_prolog_flag(stack_limit, ~I). to double the limit.'-[NewLimit]
 1116    ].

 out_of_c_stack

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

 1123out_of_c_stack -->
 1124    { statistics(c_stack, Limit), Limit > 0 },
 1125    !,
 1126    [ 'C-stack limit (~D bytes) exceeded.'-[Limit], nl ],
 1127    resolve_c_stack_overflow(Limit).
 1128out_of_c_stack -->
 1129    { statistics(c_stack, Limit), Limit > 0 },
 1130    [ 'C-stack limit exceeded.'-[Limit], nl ],
 1131    resolve_c_stack_overflow(Limit).
 1132
 1133resolve_c_stack_overflow(_Limit) -->
 1134    { thread_self(main) },
 1135    [ 'Use the shell command ' ], code('~w', 'ulimit -s size'),
 1136    [ ' to enlarge the limit.' ].
 1137resolve_c_stack_overflow(_Limit) -->
 1138    [ 'Use the ' ], code('~w', 'c_stack(KBytes)'),
 1139    [ ' option of '], code(thread_create/3), [' to enlarge the limit.' ].
 1140
 1141
 1142                 /*******************************
 1143                 *        MAKE/AUTOLOAD         *
 1144                 *******************************/
 1145
 1146prolog_message(make(reload(Files))) -->
 1147    { length(Files, N)
 1148    },
 1149    [ 'Make: reloading ~D files'-[N] ].
 1150prolog_message(make(done(_Files))) -->
 1151    [ 'Make: finished' ].
 1152prolog_message(make(library_index(Dir))) -->
 1153    [ 'Updating index for library ~w'-[Dir] ].
 1154prolog_message(autoload(Pred, File)) -->
 1155    thread_context,
 1156    [ 'autoloading ~p from ~w'-[Pred, File] ].
 1157prolog_message(autoload(read_index(Dir))) -->
 1158    [ 'Loading autoload index for ~w'-[Dir] ].
 1159prolog_message(autoload(disabled(Loaded))) -->
 1160    [ 'Disabled autoloading (loaded ~D files)'-[Loaded] ].
 1161prolog_message(autoload(already_defined(PI, From))) -->
 1162    code(PI),
 1163    (   { '$pi_head'(PI, Head),
 1164          predicate_property(Head, built_in)
 1165        }
 1166    ->  [' is a built-in predicate']
 1167    ;   [ ' is already imported from module ' ],
 1168        code(From)
 1169    ).
 1170
 1171swi_message(autoload(Msg)) -->
 1172    [ nl, '  ' ],
 1173    autoload_message(Msg).
 1174
 1175autoload_message(not_exported(PI, Spec, _FullFile, _Exports)) -->
 1176    [ ansi(code, '~w', [Spec]),
 1177      ' does not export ',
 1178      ansi(code, '~p', [PI])
 1179    ].
 1180autoload_message(no_file(Spec)) -->
 1181    [ ansi(code, '~p', [Spec]), ': No such file' ].
 1182
 1183
 1184                 /*******************************
 1185                 *       COMPILER WARNINGS      *
 1186                 *******************************/
 1187
 1188% print warnings about dubious code raised by the compiler.
 1189% TBD: pass in PC to produce exact error locations.
 1190
 1191prolog_message(compiler_warnings(Clause, Warnings0)) -->
 1192    {   print_goal_options(DefOptions),
 1193        (   prolog_load_context(variable_names, VarNames)
 1194        ->  warnings_with_named_vars(Warnings0, VarNames, Warnings),
 1195            Options = [variable_names(VarNames)|DefOptions]
 1196        ;   Options = DefOptions,
 1197            Warnings = Warnings0
 1198        )
 1199    },
 1200    compiler_warnings(Warnings, Clause, Options).
 1201
 1202warnings_with_named_vars([], _, []).
 1203warnings_with_named_vars([H|T0], VarNames, [H|T]) :-
 1204    term_variables(H, Vars),
 1205    '$member'(V1, Vars),
 1206    '$member'(_=V2, VarNames),
 1207    V1 == V2,
 1208    !,
 1209    warnings_with_named_vars(T0, VarNames, T).
 1210warnings_with_named_vars([_|T0], VarNames, T) :-
 1211    warnings_with_named_vars(T0, VarNames, T).
 1212
 1213
 1214compiler_warnings([], _, _) --> [].
 1215compiler_warnings([H|T], Clause, Options) -->
 1216    (   compiler_warning(H, Clause, Options)
 1217    ->  []
 1218    ;   [ 'Unknown compiler warning: ~W'-[H,Options] ]
 1219    ),
 1220    (   {T==[]}
 1221    ->  []
 1222    ;   [nl]
 1223    ),
 1224    compiler_warnings(T, Clause, Options).
 1225
 1226compiler_warning(eq_vv(A,B), _Clause, Options) -->
 1227    (   { A == B }
 1228    ->  [ 'Test is always true: ~W'-[A==B, Options] ]
 1229    ;   [ 'Test is always false: ~W'-[A==B, Options] ]
 1230    ).
 1231compiler_warning(eq_singleton(A,B), _Clause, Options) -->
 1232    [ 'Test is always false: ~W'-[A==B, Options] ].
 1233compiler_warning(neq_vv(A,B), _Clause, Options) -->
 1234    (   { A \== B }
 1235    ->  [ 'Test is always true: ~W'-[A\==B, Options] ]
 1236    ;   [ 'Test is always false: ~W'-[A\==B, Options] ]
 1237    ).
 1238compiler_warning(neq_singleton(A,B), _Clause, Options) -->
 1239    [ 'Test is always true: ~W'-[A\==B, Options] ].
 1240compiler_warning(unify_singleton(A,B), _Clause, Options) -->
 1241    [ 'Unified variable is not used: ~W'-[A=B, Options] ].
 1242compiler_warning(always(Bool, Pred, Arg), _Clause, Options) -->
 1243    { Goal =.. [Pred,Arg] },
 1244    [ 'Test is always ~w: ~W'-[Bool, Goal, Options] ].
 1245compiler_warning(unbalanced_var(V), _Clause, Options) -->
 1246    [ 'Variable not introduced in all branches: ~W'-[V, Options] ].
 1247compiler_warning(branch_singleton(V), _Clause, Options) -->
 1248    [ 'Singleton variable in branch: ~W'-[V, Options] ].
 1249compiler_warning(negation_singleton(V), _Clause, Options) -->
 1250    [ 'Singleton variable in \\+: ~W'-[V, Options] ].
 1251compiler_warning(multiton(V), _Clause, Options) -->
 1252    [ 'Singleton-marked variable appears more than once: ~W'-[V, Options] ].
 1253
 1254print_goal_options(
 1255    [ quoted(true),
 1256      portray(true)
 1257    ]).
 1258
 1259
 1260                 /*******************************
 1261                 *      TOPLEVEL MESSAGES       *
 1262                 *******************************/
 1263
 1264prolog_message(version) -->
 1265    { current_prolog_flag(version_git, Version) },
 1266    !,
 1267    [ '~w'-[Version] ].
 1268prolog_message(version) -->
 1269    { current_prolog_flag(version_data, swi(Major,Minor,Patch,Options))
 1270    },
 1271    (   { memberchk(tag(Tag), Options) }
 1272    ->  [ '~w.~w.~w-~w'-[Major, Minor, Patch, Tag] ]
 1273    ;   [ '~w.~w.~w'-[Major, Minor, Patch] ]
 1274    ).
 1275prolog_message(address_bits) -->
 1276    { current_prolog_flag(address_bits, Bits)
 1277    },
 1278    !,
 1279    [ '~d bits, '-[Bits] ].
 1280prolog_message(threads) -->
 1281    { current_prolog_flag(threads, true)
 1282    },
 1283    !,
 1284    [ 'threaded, ' ].
 1285prolog_message(threads) -->
 1286    [].
 1287prolog_message(copyright) -->
 1288    [ 'SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.', nl,
 1289      'Please run ', ansi(code, '?- license.', []), ' for legal details.'
 1290    ].
 1291prolog_message(documentaton) -->
 1292    [ 'For online help and background, visit ', url('https://www.swi-prolog.org') ],
 1293    (   { exists_source(library(help)) }
 1294    ->  [ nl,
 1295          'For built-in help, use ', ansi(code, '?- help(Topic).', []),
 1296          ' or ', ansi(code, '?- apropos(Word).', [])
 1297        ]
 1298    ;   []
 1299    ).
 1300prolog_message(about) -->
 1301    [ 'SWI-Prolog version (' ],
 1302    prolog_message(threads),
 1303    prolog_message(address_bits),
 1304    ['version ' ],
 1305    prolog_message(version),
 1306    [ ')', nl ],
 1307    prolog_message(copyright).
 1308prolog_message(halt) -->
 1309    [ 'halt' ].
 1310prolog_message(break(begin, Level)) -->
 1311    [ 'Break level ~d'-[Level] ].
 1312prolog_message(break(end, Level)) -->
 1313    [ 'Exit break level ~d'-[Level] ].
 1314prolog_message(var_query(_)) -->
 1315    [ '... 1,000,000 ............ 10,000,000 years later', nl, nl,
 1316      '~t~8|>> 42 << (last release gives the question)'
 1317    ].
 1318prolog_message(close_on_abort(Stream)) -->
 1319    [ 'Abort: closed stream ~p'-[Stream] ].
 1320prolog_message(cancel_halt(Reason)) -->
 1321    [ 'Halt cancelled: ~p'-[Reason] ].
 1322prolog_message(on_error(halt(Status))) -->
 1323    { statistics(errors, Errors),
 1324      statistics(warnings, Warnings)
 1325    },
 1326    [ 'Halting with status ~w due to ~D errors and ~D warnings'-
 1327      [Status, Errors, Warnings] ].
 1328
 1329prolog_message(query(QueryResult)) -->
 1330    query_result(QueryResult).
 1331
 1332query_result(no) -->            % failure
 1333    [ ansi(truth(false), 'false.', []) ],
 1334    extra_line.
 1335query_result(yes(true, [])) -->      % prompt_alternatives_on: groundness
 1336    !,
 1337    [ ansi(truth(true), 'true.', []) ],
 1338    extra_line.
 1339query_result(yes(Delays, Residuals)) -->
 1340    result([], Delays, Residuals),
 1341    extra_line.
 1342query_result(done) -->          % user typed <CR>
 1343    extra_line.
 1344query_result(yes(Bindings, Delays, Residuals)) -->
 1345    result(Bindings, Delays, Residuals),
 1346    prompt(yes, Bindings, Delays, Residuals).
 1347query_result(more(Bindings, Delays, Residuals)) -->
 1348    result(Bindings, Delays, Residuals),
 1349    prompt(more, Bindings, Delays, Residuals).
 1350:- if(current_prolog_flag(emscripten, true)). 1351query_result(help) -->
 1352    [ ansi(bold, '  Possible actions:', []), nl,
 1353      '  ; (n,r,space): redo              | t:       trace&redo'-[], nl,
 1354      '  *:             show choicepoint  | . (c,a): stop'-[], nl,
 1355      '  w:             write             | p:       print'-[], nl,
 1356      '  +:             max_depth*5       | -:       max_depth//5'-[], nl,
 1357      '  h (?):         help'-[],
 1358      nl, nl
 1359    ].
 1360:- else. 1361query_result(help) -->
 1362    [ ansi(bold, '  Possible actions:', []), nl,
 1363      '  ; (n,r,space,TAB): redo              | t:           trace&redo'-[], nl,
 1364      '  *:                 show choicepoint  | . (c,a,RET): stop'-[], nl,
 1365      '  w:                 write             | p:           print'-[], nl,
 1366      '  +:                 max_depth*5       | -:           max_depth//5'-[], nl,
 1367      '  b:                 break             | h (?):       help'-[],
 1368      nl, nl
 1369    ].
 1370:- endif. 1371query_result(action) -->
 1372    [ 'Action? '-[], flush ].
 1373query_result(confirm) -->
 1374    [ 'Please answer \'y\' or \'n\'? '-[], flush ].
 1375query_result(eof) -->
 1376    [ nl ].
 1377query_result(toplevel_open_line) -->
 1378    [].
 1379
 1380prompt(Answer, [], true, []-[]) -->
 1381    !,
 1382    prompt(Answer, empty).
 1383prompt(Answer, _, _, _) -->
 1384    !,
 1385    prompt(Answer, non_empty).
 1386
 1387prompt(yes, empty) -->
 1388    !,
 1389    [ ansi(truth(true), 'true.', []) ],
 1390    extra_line.
 1391prompt(yes, _) -->
 1392    !,
 1393    [ full_stop ],
 1394    extra_line.
 1395prompt(more, empty) -->
 1396    !,
 1397    [ ansi(truth(true), 'true ', []), flush ].
 1398prompt(more, _) -->
 1399    !,
 1400    [ ' '-[], flush ].
 1401
 1402result(Bindings, Delays, Residuals) -->
 1403    { current_prolog_flag(answer_write_options, Options0),
 1404      Options = [partial(true)|Options0],
 1405      GOptions = [priority(999)|Options0]
 1406    },
 1407    wfs_residual_program(Delays, GOptions),
 1408    bindings(Bindings, [priority(699)|Options]),
 1409    (   {Residuals == []-[]}
 1410    ->  bind_delays_sep(Bindings, Delays),
 1411        delays(Delays, GOptions)
 1412    ;   bind_res_sep(Bindings, Residuals),
 1413        residuals(Residuals, GOptions),
 1414        (   {Delays == true}
 1415        ->  []
 1416        ;   [','-[], nl],
 1417            delays(Delays, GOptions)
 1418        )
 1419    ).
 1420
 1421bindings([], _) -->
 1422    [].
 1423bindings([binding(Names,Skel,Subst)|T], Options) -->
 1424    { '$last'(Names, Name) },
 1425    var_names(Names), value(Name, Skel, Subst, Options),
 1426    (   { T \== [] }
 1427    ->  [ ','-[], nl ],
 1428        bindings(T, Options)
 1429    ;   []
 1430    ).
 1431
 1432var_names([Name]) -->
 1433    !,
 1434    [ '~w = '-[Name] ].
 1435var_names([Name1,Name2|T]) -->
 1436    !,
 1437    [ '~w = ~w, '-[Name1, Name2] ],
 1438    var_names([Name2|T]).
 1439
 1440
 1441value(Name, Skel, Subst, Options) -->
 1442    (   { var(Skel), Subst = [Skel=S] }
 1443    ->  { Skel = '$VAR'(Name) },
 1444        [ '~W'-[S, Options] ]
 1445    ;   [ '~W'-[Skel, Options] ],
 1446        substitution(Subst, Options)
 1447    ).
 1448
 1449substitution([], _) --> !.
 1450substitution([N=V|T], Options) -->
 1451    [ ', ', ansi(comment, '% where', []), nl,
 1452      '    ~w = ~W'-[N,V,Options] ],
 1453    substitutions(T, Options).
 1454
 1455substitutions([], _) --> [].
 1456substitutions([N=V|T], Options) -->
 1457    [ ','-[], nl, '    ~w = ~W'-[N,V,Options] ],
 1458    substitutions(T, Options).
 1459
 1460
 1461residuals(Normal-Hidden, Options) -->
 1462    residuals1(Normal, Options),
 1463    bind_res_sep(Normal, Hidden),
 1464    (   {Hidden == []}
 1465    ->  []
 1466    ;   [ansi(comment, '% with pending residual goals', []), nl]
 1467    ),
 1468    residuals1(Hidden, Options).
 1469
 1470residuals1([], _) -->
 1471    [].
 1472residuals1([G|Gs], Options) -->
 1473    (   { Gs \== [] }
 1474    ->  [ '~W,'-[G, Options], nl ],
 1475        residuals1(Gs, Options)
 1476    ;   [ '~W'-[G, Options] ]
 1477    ).
 1478
 1479wfs_residual_program(true, _Options) -->
 1480    !.
 1481wfs_residual_program(Goal, _Options) -->
 1482    { current_prolog_flag(toplevel_list_wfs_residual_program, true),
 1483      '$current_typein_module'(TypeIn),
 1484      (   current_predicate(delays_residual_program/2)
 1485      ->  true
 1486      ;   use_module(library(wfs), [delays_residual_program/2])
 1487      ),
 1488      delays_residual_program(TypeIn:Goal, TypeIn:Program),
 1489      Program \== []
 1490    },
 1491    !,
 1492    [ ansi(comment, '% WFS residual program', []), nl ],
 1493    [ ansi(wfs(residual_program), '~@', ['$messages':list_clauses(Program)]) ].
 1494wfs_residual_program(_, _) --> [].
 1495
 1496delays(true, _Options) -->
 1497    !.
 1498delays(Goal, Options) -->
 1499    { current_prolog_flag(toplevel_list_wfs_residual_program, true)
 1500    },
 1501    !,
 1502    [ ansi(truth(undefined), '~W', [Goal, Options]) ].
 1503delays(_, _Options) -->
 1504    [ ansi(truth(undefined), undefined, []) ].
 1505
 1506:- public list_clauses/1. 1507
 1508list_clauses([]).
 1509list_clauses([H|T]) :-
 1510    (   system_undefined(H)
 1511    ->  true
 1512    ;   portray_clause(user_output, H, [indent(4)])
 1513    ),
 1514    list_clauses(T).
 1515
 1516system_undefined((undefined :- tnot(undefined))).
 1517system_undefined((answer_count_restraint :- tnot(answer_count_restraint))).
 1518system_undefined((radial_restraint :- tnot(radial_restraint))).
 1519
 1520bind_res_sep(_, []) --> !.
 1521bind_res_sep(_, []-[]) --> !.
 1522bind_res_sep([], _) --> !.
 1523bind_res_sep(_, _) --> [','-[], nl].
 1524
 1525bind_delays_sep([], _) --> !.
 1526bind_delays_sep(_, true) --> !.
 1527bind_delays_sep(_, _) --> [','-[], nl].
 1528
 1529extra_line -->
 1530    { current_prolog_flag(toplevel_extra_white_line, true) },
 1531    !,
 1532    ['~N'-[]].
 1533extra_line -->
 1534    [].
 1535
 1536prolog_message(if_tty(Message)) -->
 1537    (   {current_prolog_flag(tty_control, true)}
 1538    ->  [ at_same_line ], list(Message)
 1539    ;   []
 1540    ).
 1541prolog_message(halt(Reason)) -->
 1542    [ '~w: halt'-[Reason] ].
 1543prolog_message(no_action(Char)) -->
 1544    [ 'Unknown action: ~c (h for help)'-[Char], nl ].
 1545
 1546prolog_message(history(help(Show, Help))) -->
 1547    [ 'History Commands:', nl,
 1548      '    !!.              Repeat last query', nl,
 1549      '    !nr.             Repeat query numbered <nr>', nl,
 1550      '    !str.            Repeat last query starting with <str>', nl,
 1551      '    !?str.           Repeat last query holding <str>', nl,
 1552      '    ^old^new.        Substitute <old> into <new> of last query', nl,
 1553      '    !nr^old^new.     Substitute in query numbered <nr>', nl,
 1554      '    !str^old^new.    Substitute in query starting with <str>', nl,
 1555      '    !?str^old^new.   Substitute in query holding <str>', nl,
 1556      '    ~w.~21|Show history list'-[Show], nl,
 1557      '    ~w.~21|Show this list'-[Help], nl, nl
 1558    ].
 1559prolog_message(history(no_event)) -->
 1560    [ '! No such event' ].
 1561prolog_message(history(bad_substitution)) -->
 1562    [ '! Bad substitution' ].
 1563prolog_message(history(expanded(Event))) -->
 1564    [ '~w.'-[Event] ].
 1565prolog_message(history(history(Events))) -->
 1566    history_events(Events).
 1567
 1568history_events([]) -->
 1569    [].
 1570history_events([Nr/Event|T]) -->
 1571    [ '~t~w   ~8|~W~W'-[ Nr,
 1572                         Event, [partial(true)],
 1573                         '.', [partial(true)]
 1574                       ],
 1575      nl
 1576    ],
 1577    history_events(T).