/* $Id: debug.pl,v 1.1 2008-02-12 17:03:53 vsc Exp $
Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: jan@swi.psy.uva.nl
WWW: http://www.swi-prolog.org
Copyright (C): 1985-2002, University of Amsterdam
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
As a special exception, if you link this library with other files,
compiled with a Free Software compiler, to produce an executable, this
library does not by itself cause the resulting executable to be covered
by the GNU General Public License. This exception does not however
invalidate any other reasons why the executable file might be covered by
the GNU General Public License.
*/
:- 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,
assertion/1 % :Goal
]).
:- meta_predicate(assertion(:)).
:- set_prolog_flag(generate_debug_info, false).
:- if(current_prolog_flag(dialect, yap)).
:- use_module(library(hacks), [stack_dump/1]).
% this is as good as I can do.
backtrace(N) :-
stack_dump(N).
:- endif.
:- dynamic
debugging/2.
/** <module> Print debug messages
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 monitorring 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.
%
% Check whether we are debugging Topic or enumerate the topics we
% are debugging.
debugging(Topic) :-
debugging(Topic, true).
%% 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 a a (load-)file without warnings.
debug(Topic) :-
debug(Topic, true).
nodebug(Topic) :-
debug(Topic, false).
debug(Topic, Val) :-
( ( retract(debugging(Topic, _))
*-> assert(debugging(Topic, Val)),
fail
; ( prolog_load_context(file, _)
-> true
; print_message(warning, debug_no_topic(Topic))
),
assert(debugging(Topic, Val))
)
-> true
; true
).
%% 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~40|~n', "-"),
format(user_error, '~w~t~30| ~w~n', ['Debug Topic', 'Activated']),
format(user_error, '~*t~40|~n', "-"),
( debugging(Topic, Value),
format(user_error, '~w~t~30| ~w~n', [Topic, Value]),
fail
; true
).
%% debug(+Topic, +Format, +Args) is det.
%
% As format/3 to user_error, but only does something if Topic
% is activated through debug/1.
debug(Topic, Format, Args) :-
debugging(Topic, true), !,
print_debug(Topic, Format, Args).
debug(_, _, _).
:- multifile
prolog:debug_print_hook/3.
print_debug(Topic, Format, Args) :-
prolog:debug_print_hook(Topic, Format, Args), !.
print_debug(_, Format, Args) :-
print_message(informational, debug(Format, Args)).
/*******************************
* ASSERTION *
*******************************/
%% assertion(: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.
assertion(G) :-
\+ \+ G, !. % avoid binding variables
assertion(G) :-
print_message(error, assumption_failed(G)),
backtrace(10),
trace,
assertion_failed.
assertion_failed.
%% 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 *
*******************************/
:- multifile
user:goal_expansion/2.
user:goal_expansion(debug(Topic,_,_), true) :-
( current_prolog_flag(optimise, true)
-> true
; debug_topic(Topic),
fail
).
user:goal_expansion(debugging(Topic), fail) :-
( current_prolog_flag(optimise, true)
-> true
; debug_topic(Topic),
fail
).
user:goal_expansion(assertion(G), Goal) :-
( current_prolog_flag(optimise, true)
-> Goal = true
; expand_goal(G, G2),
Goal = assertion(G2)
).
user:goal_expansion(assume(G), Goal) :-
print_message(informational,
compatibility(renamed(assume/1, assertion/1))),
( current_prolog_flag(optimise, true)
-> Goal = true
; expand_goal(G, G2),
Goal = assertion(G2)
).
/*******************************
* MESSAGES *
*******************************/
:- multifile
prolog:message/3.
prolog:message(assumption_failed(G)) -->
[ 'Assertion failed: ~p'-[G] ].
prolog:message(debug(Fmt, Args)) -->
{ thread_self(Me) },
( { Me == main }
-> [ Fmt-Args ]
; [ '[Thread ~w] '-[Me], Fmt-Args ]
).
prolog:message(debug_no_topic(Topic)) -->
[ '~q: no matching debug topic (yet)'-[Topic] ].