/* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (C): 1985-2012, University of Amsterdam
VU University 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 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,
debug_message_context/1, % (+|-)What
assertion/1 % :Goal
]).
:- use_module(library(error)).
:- use_module(library(lists)).
:- 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
debug_context/1.
debug_context(thread).
/** <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) :-
debug(Topic, true).
nodebug(Topic) :-
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) :- !,
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),
format(user_error, '~w~t ~w~35| ~w~n', [Topic, Value, To]),
fail
; true
).
%% debug_message_context(+What) is det.
%
% Specify additional context for debug messages. What is one of
% +Context or -Context, and Context is one of =thread=, =time= or
% time(Format), where Format is a format specification for
% format_time/3 (default is =|%T.%3f|=). Initially, debug/3 shows
% only thread information.
debug_message_context(+Topic) :- !,
valid_topic(Topic, Del, Add),
retractall(debug_context(Del)),
assert(debug_context(Add)).
debug_message_context(-Topic) :- !,
valid_topic(Topic, Del, _),
retractall(debug_context(Del)).
debug_message_context(Term) :-
type_error(debug_message_context, Term).
valid_topic(thread, thread, thread) :- !.
valid_topic(time, time(_), time('%T.%3f')) :- !.
valid_topic(time(Format), time(_), time(Format)) :- !.
valid_topic(X, _, _) :-
domain_error(debug_message_context, X).
%% 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) :-
prolog:debug_print_hook(Topic, Format, Args), !.
print_debug(_, [], _, _) :- !.
print_debug(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, 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.
%% 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
system:goal_expansion/2.
system:goal_expansion(debug(Topic,_,_), true) :-
( current_prolog_flag(optimise, true)
-> true
; debug_topic(Topic),
fail
).
system:goal_expansion(debugging(Topic), fail) :-
( current_prolog_flag(optimise, true)
-> true
; debug_topic(Topic),
fail
).
system:goal_expansion(assertion(_), Goal) :-
current_prolog_flag(optimise, true),
Goal = true.
system:goal_expansion(assume(_), Goal) :-
print_message(informational,
compatibility(renamed(assume/1, assertion/1))),
current_prolog_flag(optimise, true),
Goal = true.
/*******************************
* MESSAGES *
*******************************/
:- multifile
prolog:message/3.
prolog:message(assertion_failed(_, G)) -->
[ 'Assertion failed: ~q'-[G] ].
prolog:message(debug(Fmt, Args)) -->
show_thread_context,
show_time_context,
[ Fmt-Args ].
prolog:message(debug_no_topic(Topic)) -->
[ '~q: no matching debug topic (yet)'-[Topic] ].
show_thread_context -->
{ debug_context(thread),
thread_self(Me) ,
Me \== main
},
[ '[Thread ~w] '-[Me] ].
show_thread_context -->
[].
show_time_context -->
{ debug_context(time(Format)),
get_time(Now),
format_time(string(S), Format, Now)
},
[ '[~w] '-[S] ].
show_time_context -->
[].
/*******************************
* 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.