/* Part of SWI-Prolog Author: Jan Wielemaker E-mail: J.Wielemaker@vu.nl WWW: http://www.swi-prolog.org Copyright (c) 2002-2023, University of Amsterdam VU University Amsterdam CWI, Amsterdam SWI-Prolog Solutions b.v. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ :- module(prolog_debug, [ debug/3, % +Topic, +Format, :Args debug/1, % +Topic nodebug/1, % +Topic debugging/1, % ?Topic debugging/2, % ?Topic, ?Bool list_debug_topics/0, list_debug_topics/1, % +Options debug_message_context/1, % (+|-)What assertion/1 % :Goal ]). :- autoload(library(lists),[append/3,delete/3,selectchk/3,member/2]). :- autoload(library(prolog_stack),[backtrace/1]). :- autoload(library(option), [option/3, option/2]). :- set_prolog_flag(generate_debug_info, false). :- meta_predicate assertion(0), debug(+,+,:). :- multifile prolog:assertion_failed/2. :- dynamic prolog:assertion_failed/2. /*:- use_module(library(prolog_stack)).*/ % We use the autoloader if needed %:- set_prolog_flag(generate_debug_info, false). :- dynamic debugging/3. % Topic, Enabled, To /** Print debug messages and test assertions This library is a replacement for format/3 for printing debug messages. Messages are assigned a _topic_. By dynamically enabling or disabling topics the user can select desired messages. Calls to debug/3 and assertion/1 are removed when the code is compiled for optimization unless the Prolog flag `optimise_debug` is set to `true`. Using the predicate assertion/1 you can make assumptions about your program explicit, trapping the debugger if the condition does not hold. Output and actions by these predicates can be configured using _hooks_ to fit your environment. With XPCE, you can use the call below to start a graphical monitoring tool. ?- prolog_ide(debug_monitor). */ %! debugging(+Topic) is semidet. %! debugging(-Topic) is nondet. %! debugging(?Topic, ?Bool) is nondet. % % Examine debug topics. The form debugging(+Topic) may be used to % perform more complex debugging tasks. A typical usage skeleton % is: % % ``` % ( debugging(mytopic) % -> % ; true % ), % ... % ``` % % The other two calls are intended to examine existing and enabled % debugging tokens and are typically not used in user programs. debugging(Topic) :- debugging(Topic, true, _To). debugging(Topic, Bool) :- debugging(Topic, Bool, _To). %! debug(+Topic) is det. %! nodebug(+Topic) is det. % % Add/remove a topic from being printed. nodebug(_) removes all % topics. Gives a warning if the topic is not defined unless it is % used from a directive. The latter allows placing debug topics at the % start of a (load-)file without warnings. % % For debug/1, Topic can be a term `Topic > Out`, where `Out` is % either a stream or stream-alias or a filename (an atom). This % redirects debug information on this topic to the given output. On % Linux systems redirection can be used to make the message appear, % even if the `user_error` stream is redefined using % % ?- debug(Topic > '/proc/self/fd/2'). % % A platform independent way to get debug messages in the current % console (for example, a `swipl-win` window, or login using `ssh` to % Prolog running an SSH server from the `libssh` pack) is to use: % % ?- stream_property(S, alias(user_error)), % debug(Topic > S). % % Do not forget to disable the debugging using nodebug/1 before % quitting the console if Prolog must remain running. debug(Topic) :- with_mutex(prolog_debug, debug(Topic, true)). nodebug(Topic) :- with_mutex(prolog_debug, debug(Topic, false)). debug(Spec, Val) :- debug_target(Spec, Topic, Out), ( ( retract(debugging(Topic, Enabled0, To0)) *-> update_debug(Enabled0, To0, Val, Out, Enabled, To), assert(debugging(Topic, Enabled, To)), fail ; ( prolog_load_context(file, _) -> true ; print_message(warning, debug_no_topic(Topic)) ), update_debug(false, [], Val, Out, Enabled, To), assert(debugging(Topic, Enabled, To)) ) -> true ; true ). debug_target(Spec, Topic, To) :- nonvar(Spec), Spec = (Topic > To), !. debug_target(Topic, Topic, -). update_debug(_, To0, true, -, true, To) :- !, ensure_output(To0, To). update_debug(true, To0, true, Out, true, Output) :- !, ( memberchk(Out, To0) -> Output = To0 ; append(To0, [Out], Output) ). update_debug(false, _, true, Out, true, [Out]) :- !. update_debug(_, _, false, -, false, []) :- !. update_debug(true, [Out], false, Out, false, []) :- !. update_debug(true, To0, false, Out, true, Output) :- !, delete(To0, Out, Output). ensure_output([], [user_error]) :- !. ensure_output(List, List). %! debug_topic(+Topic) is det. % % Declare a topic for debugging. This can be used to find all % topics available for debugging. debug_topic(Topic) :- ( debugging(Registered, _, _), Registered =@= Topic -> true ; assert(debugging(Topic, false, [])) ). %! list_debug_topics is det. %! list_debug_topics(+Options) is det. % % List currently known topics for debug/3 and their setting. Options % is either an atom or string, which is a shorthand for % `[search(String)]` or a normal option list. Defined options are: % % - search(String) % Only show topics that match String. Match is case insensitive % on the printed representation of the term. % - active(+Boolean) % Only print topics that are active (`true`) or inactive % (`false`). % - output(+To) % Only print topics whose target location matches To. This option % implicitly restricts the output to active topics. list_debug_topics :- list_debug_topics([]). list_debug_topics(Options) :- ( atom(Options) ; string(Options) ), !, list_debug_topics([search(Options)]). list_debug_topics(Options) :- print_message(information, debug_topics(header)), option(active(Value), Options, _), ( debugging(Topic, Value, To), ( option(output(Stream), Options) -> memberchk(Stream, To) ; true ), numbervars(Topic, 0, _, [singletons(true)]), term_string(Topic, String, [quoted(true), numbervars(true)]), ( option(search(Search), Options) -> sub_atom_icasechk(String, _, Search) ; true ), print_message(information, debug_topic(Topic, String, Value, To)), fail ; true ). :- multifile prolog_debug_tools:debugging_hook/0. prolog_debug_tools:debugging_hook :- ( debugging(_, true) -> list_debug_topics([active(true)]) ). %! debug_message_context(+What) is det. % % Specify additional context for debug messages. % % @deprecated New code should use the Prolog flag `message_context`. % This predicates adds or deletes topics from this list. debug_message_context(+Topic) :- current_prolog_flag(message_context, List), ( memberchk(Topic, List) -> true ; append(List, [Topic], List2), set_prolog_flag(message_context, List2) ). debug_message_context(-Topic) :- current_prolog_flag(message_context, List), ( selectchk(Topic, List, Rest) -> set_prolog_flag(message_context, Rest) ; true ). %! debug(+Topic, +Format, :Args) is det. % % Format a message if debug topic is enabled. Similar to format/3 % to =user_error=, but only prints if Topic is activated through % debug/1. Args is a meta-argument to deal with goal for the % @-command. Output is first handed to the hook % prolog:debug_print_hook/3. If this fails, Format+Args is % translated to text using the message-translation (see % print_message/2) for the term debug(Format, Args) and then % printed to every matching destination (controlled by debug/1) % using print_message_lines/3. % % The message is preceded by '% ' and terminated with a newline. % % @see format/3. debug(Topic, Format, Args) :- debugging(Topic, true, To), !, print_debug(Topic, To, Format, Args). debug(_, _, _). %! prolog:debug_print_hook(+Topic, +Format, +Args) is semidet. % % Hook called by debug/3. This hook is used by the graphical % frontend that can be activated using prolog_ide/1: % % == % ?- prolog_ide(debug_monitor). % == :- multifile prolog:debug_print_hook/3. print_debug(_Topic, _To, _Format, _Args) :- nb_current(prolog_debug_printing, true), !. print_debug(Topic, To, Format, Args) :- setup_call_cleanup( nb_setval(prolog_debug_printing, true), print_debug_guarded(Topic, To, Format, Args), nb_delete(prolog_debug_printing)). print_debug_guarded(Topic, _To, Format, Args) :- prolog:debug_print_hook(Topic, Format, Args), !. print_debug_guarded(_, [], _, _) :- !. print_debug_guarded(Topic, To, Format, Args) :- phrase('$messages':translate_message(debug(Format, Args)), Lines), ( member(T, To), debug_output(T, Stream), with_output_to( Stream, print_message_lines(current_output, kind(debug(Topic)), Lines)), fail ; true ). debug_output(user, user_error) :- !. debug_output(Stream, Stream) :- is_stream(Stream), !. debug_output(File, Stream) :- open(File, append, Stream, [ close_on_abort(false), alias(File), buffer(line) ]). /******************************* * ASSERTION * *******************************/ %! assertion(:Goal) is det. % % Acts similar to C assert() macro. It has no effect if Goal % succeeds. If Goal fails or throws an exception, the following % steps are taken: % % * call prolog:assertion_failed/2. If prolog:assertion_failed/2 % fails, then: % % - If this is an interactive toplevel thread, print a % message, the stack-trace, and finally trap the debugger. % - Otherwise, throw error(assertion_error(Reason, G),_) where % Reason is one of =fail= or the exception raised. assertion(G) :- \+ \+ catch(G, Error, assertion_failed(Error, G)), !. assertion(G) :- assertion_failed(fail, G), assertion_failed. % prevent last call optimization. assertion_failed(Reason, G) :- prolog:assertion_failed(Reason, G), !. assertion_failed(Reason, _) :- assertion_rethrow(Reason), !, throw(Reason). assertion_failed(Reason, G) :- print_message(error, assertion_failed(Reason, G)), backtrace(10), ( current_prolog_flag(break_level, _) % interactive thread -> trace ; throw(error(assertion_error(Reason, G), _)) ). assertion_failed. assertion_rethrow(time_limit_exceeded). assertion_rethrow('$aborted'). /******************************* * EXPANSION * *******************************/ % The optimise_debug flag defines whether Prolog optimizes % away assertions and debug/3 statements. Values are =true= % (debug is optimized away), =false= (debug is retained) and % =default= (debug optimization is dependent on the optimise % flag). optimise_debug :- ( current_prolog_flag(optimise_debug, true) -> true ; current_prolog_flag(optimise_debug, default), current_prolog_flag(optimise, true) -> true ). :- multifile system:goal_expansion/2. system:goal_expansion(debug(Topic,_,_), true) :- ( optimise_debug -> true ; debug_topic(Topic), fail ). system:goal_expansion(debugging(Topic), fail) :- ( optimise_debug -> true ; debug_topic(Topic), fail ). system:goal_expansion(assertion(_), true) :- optimise_debug. system:goal_expansion(assume(_), true) :- print_message(informational, compatibility(renamed(assume/1, assertion/1))), optimise_debug. /******************************* * MESSAGES * *******************************/ :- multifile prolog:message/3. prolog:message(assertion_failed(_, G)) --> [ 'Assertion failed: ~q'-[G] ]. prolog:message(debug(Fmt, Args)) --> [ Fmt-Args ]. prolog:message(debug_no_topic(Topic)) --> [ '~q: no matching debug topic (yet)'-[Topic] ]. prolog:message(debug_topics(header)) --> [ ansi(bold, '~w~t ~w~35| ~w~n', ['Debug Topic', 'Activated', 'To']), '~`\u2015t~48|' ]. prolog:message(debug_topic(_, TopicString, true, [user_error])) --> [ ansi(bold, '~s~t \u2714~35|', [TopicString]) ]. prolog:message(debug_topic(_, TopicString, true, To)) --> [ ansi(bold, '~s~t \u2714~35| ~q', [TopicString, To]) ]. prolog:message(debug_topic(_, TopicString, false, _To)) --> [ '~s~t -~35|'-[TopicString] ]. /******************************* * HOOKS * *******************************/ %! prolog:assertion_failed(+Reason, +Goal) is semidet. % % This hook is called if the Goal of assertion/1 fails. Reason is % unified with either =fail= if Goal simply failed or an exception % call otherwise. If this hook fails, the default behaviour is % activated. If the hooks throws an exception it will be % propagated into the caller of assertion/1. /******************************* * SANDBOX * *******************************/ :- multifile sandbox:safe_meta/2. sandbox:safe_meta(prolog_debug:assertion(X), [X]).