/* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (c) 2002-2018, University of Amsterdam
VU University Amsterdam
CWI, Amsterdam
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,
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]).
:- 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
/** <module> 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. Debug statements are
removed when the code is compiled for optimization.
See manual for details. With XPCE, you can use the call below to start a
graphical monitoring tool.
==
?- prolog_ide(debug_monitor).
==
Using the predicate assertion/1 you can make assumptions about your
program explicit, trapping the debugger if the condition does not hold.
@author Jan Wielemaker
*/
%! 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)
% -> <perform debugging actions>
% ; 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 (atom). This
% redirects debug information on this topic to the given output.
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 currently known debug topics and their setting.
list_debug_topics :-
format(user_error, '~`-t~45|~n', []),
format(user_error, '~w~t ~w~35| ~w~n',
['Debug Topic', 'Activated', 'To']),
format(user_error, '~`-t~45|~n', []),
( debugging(Topic, Value, To),
numbervars(Topic, 0, _, [singletons(true)]),
format(user_error, '~W~t ~w~35| ~w~n',
[Topic, [quoted(true), numbervars(true)], Value, To]),
fail
; 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').
%! assume(:Goal) is det.
%
% Acts similar to C assert() macro. It has no effect of Goal
% succeeds. If Goal fails it prints a message, a stack-trace
% and finally traps the debugger.
%
% @deprecated Use assertion/1 in new code.
/*******************************
* 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] ].
/*******************************
* 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]).