yap-6.3/library/timeout.yap

/*************************************************************************
*									 *
*	 YAP Prolog 							 *
*									 *
*	Yap Prolog was developed at NCCUP - Universidade do Porto	 *
*									 *
* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997	 *
*									 *
**************************************************************************
*									 *
* File:		timeout.yap						 *
* Last rev:	5/12/99							 *
* mods:									 *
* comments:	Goal within timeout					 *
*									 *
*************************************************************************/

:- module(timeout, [
	time_out/3
    ]).

:- meta_predicate time_out(:,+,-).

%
% not the nicest program I've ever seen.
%
time_out(Goal, Time, Result) :-
	T is Time//1000,
	UT is (Time mod 1000)*1000,
	% enable alarm
	alarm(T.UT,throw(time_out),_),
	% launch goal and wait for signal
	( catch(Goal, time_out, Result = time_out)
        % make sure to disable alarm
          ->
	    alarm(0,_,_)
	  ;
	    alarm(0,_,_),
	    fail
	),
	% just couldn't resist...
	(Result = success -> true ; true).