%%% -*- Mode: Prolog; -*-

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  $Date: 2010-12-02 15:20:15 +0100 (Thu, 02 Dec 2010) $
%  $Revision: 5043 $
%
%  This file is part of ProbLog
%  http://dtai.cs.kuleuven.be/problog
%
%  ProbLog was developed at Katholieke Universiteit Leuven
%                                                            
%  Copyright 2008, 2009, 2010
%  Katholieke Universiteit Leuven
%                                                              
%  Main authors of this file:
%  Bernd Gutmann
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% Artistic License 2.0
% 
% Copyright (c) 2000-2006, The Perl Foundation.
% 
% Everyone is permitted to copy and distribute verbatim copies of this
% license document, but changing it is not allowed.  Preamble
% 
% This license establishes the terms under which a given free software
% Package may be copied, modified, distributed, and/or
% redistributed. The intent is that the Copyright Holder maintains some
% artistic control over the development of that Package while still
% keeping the Package available as open source and free software.
% 
% You are always permitted to make arrangements wholly outside of this
% license directly with the Copyright Holder of a given Package. If the
% terms of this license do not permit the full use that you propose to
% make of the Package, you should contact the Copyright Holder and seek
% a different licensing arrangement.  Definitions
% 
% "Copyright Holder" means the individual(s) or organization(s) named in
% the copyright notice for the entire Package.
% 
% "Contributor" means any party that has contributed code or other
% material to the Package, in accordance with the Copyright Holder's
% procedures.
% 
% "You" and "your" means any person who would like to copy, distribute,
% or modify the Package.
% 
% "Package" means the collection of files distributed by the Copyright
% Holder, and derivatives of that collection and/or of those files. A
% given Package may consist of either the Standard Version, or a
% Modified Version.
% 
% "Distribute" means providing a copy of the Package or making it
% accessible to anyone else, or in the case of a company or
% organization, to others outside of your company or organization.
% 
% "Distributor Fee" means any fee that you charge for Distributing this
% Package or providing support for this Package to another party. It
% does not mean licensing fees.
% 
% "Standard Version" refers to the Package if it has not been modified,
% or has been modified only in ways explicitly requested by the
% Copyright Holder.
% 
% "Modified Version" means the Package, if it has been changed, and such
% changes were not explicitly requested by the Copyright Holder.
% 
% "Original License" means this Artistic License as Distributed with the
% Standard Version of the Package, in its current version or as it may
% be modified by The Perl Foundation in the future.
% 
% "Source" form means the source code, documentation source, and
% configuration files for the Package.
% 
% "Compiled" form means the compiled bytecode, object code, binary, or
% any other form resulting from mechanical transformation or translation
% of the Source form.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% Permission for Use and Modification Without Distribution
% 
% (1) You are permitted to use the Standard Version and create and use
% Modified Versions for any purpose without restriction, provided that
% you do not Distribute the Modified Version.
%
% Permissions for Redistribution of the Standard Version
% 
% (2) You may Distribute verbatim copies of the Source form of the
% Standard Version of this Package in any medium without restriction,
% either gratis or for a Distributor Fee, provided that you duplicate
% all of the original copyright notices and associated disclaimers. At
% your discretion, such verbatim copies may or may not include a
% Compiled form of the Package.
% 
% (3) You may apply any bug fixes, portability changes, and other
% modifications made available from the Copyright Holder. The resulting
% Package will still be considered the Standard Version, and as such
% will be subject to the Original License.
%
% Distribution of Modified Versions of the Package as Source
% 
% (4) You may Distribute your Modified Version as Source (either gratis
% or for a Distributor Fee, and with or without a Compiled form of the
% Modified Version) provided that you clearly document how it differs
% from the Standard Version, including, but not limited to, documenting
% any non-standard features, executables, or modules, and provided that
% you do at least ONE of the following:
% 
% (a) make the Modified Version available to the Copyright Holder of the
% Standard Version, under the Original License, so that the Copyright
% Holder may include your modifications in the Standard Version.  (b)
% ensure that installation of your Modified Version does not prevent the
% user installing or running the Standard Version. In addition, the
% modified Version must bear a name that is different from the name of
% the Standard Version.  (c) allow anyone who receives a copy of the
% Modified Version to make the Source form of the Modified Version
% available to others under (i) the Original License or (ii) a license
% that permits the licensee to freely copy, modify and redistribute the
% Modified Version using the same licensing terms that apply to the copy
% that the licensee received, and requires that the Source form of the
% Modified Version, and of any works derived from it, be made freely
% available in that license fees are prohibited but Distributor Fees are
% allowed.
%
% Distribution of Compiled Forms of the Standard Version or
% Modified Versions without the Source
% 
% (5) You may Distribute Compiled forms of the Standard Version without
% the Source, provided that you include complete instructions on how to
% get the Source of the Standard Version. Such instructions must be
% valid at the time of your distribution. If these instructions, at any
% time while you are carrying out such distribution, become invalid, you
% must provide new instructions on demand or cease further
% distribution. If you provide valid instructions or cease distribution
% within thirty days after you become aware that the instructions are
% invalid, then you do not forfeit any of your rights under this
% license.
% 
% (6) You may Distribute a Modified Version in Compiled form without the
% Source, provided that you comply with Section 4 with respect to the
% Source of the Modified Version.
%
% Aggregating or Linking the Package
% 
% (7) You may aggregate the Package (either the Standard Version or
% Modified Version) with other packages and Distribute the resulting
% aggregation provided that you do not charge a licensing fee for the
% Package. Distributor Fees are permitted, and licensing fees for other
% components in the aggregation are permitted. The terms of this license
% apply to the use and Distribution of the Standard or Modified Versions
% as included in the aggregation.
% 
% (8) You are permitted to link Modified and Standard Versions with
% other works, to embed the Package in a larger work of your own, or to
% build stand-alone binary or bytecode versions of applications that
% include the Package, and Distribute the result without restriction,
% provided the result does not expose a direct interface to the Package.
%
% Items That are Not Considered Part of a Modified Version
% 
% (9) Works (including, but not limited to, modules and scripts) that
% merely extend or make use of the Package, do not, by themselves, cause
% the Package to be a Modified Version. In addition, such works are not
% considered parts of the Package itself, and are not subject to the
% terms of this license.
%
% General Provisions
% 
% (10) Any use, modification, and distribution of the Standard or
% Modified Versions is governed by this Artistic License. By using,
% modifying or distributing the Package, you accept this license. Do not
% use, modify, or distribute the Package, if you do not accept this
% license.
% 
% (11) If your Modified Version has been derived from a Modified Version
% made by someone other than you, you are nevertheless required to
% ensure that your Modified Version complies with the requirements of
% this license.
% 
% (12) This license does not grant you the right to use any trademark,
% service mark, tradename, or logo of the Copyright Holder.
% 
% (13) This license includes the non-exclusive, worldwide,
% free-of-charge patent license to make, have made, use, offer to sell,
% sell, import and otherwise transfer the Package with respect to any
% patent claims licensable by the Copyright Holder that are necessarily
% infringed by the Package. If you institute patent litigation
% (including a cross-claim or counterclaim) against any party alleging
% that the Package constitutes direct or contributory patent
% infringement, then this Artistic License to you shall terminate on the
% date that such litigation is filed.
% 
% (14) Disclaimer of Warranty: THE PACKAGE IS PROVIDED BY THE COPYRIGHT
% HOLDER AND CONTRIBUTORS "AS IS' AND WITHOUT ANY EXPRESS OR IMPLIED
% WARRANTIES. THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
% PARTICULAR PURPOSE, OR NON-INFRINGEMENT ARE DISCLAIMED TO THE EXTENT
% PERMITTED BY YOUR LOCAL LAW. UNLESS REQUIRED BY LAW, NO COPYRIGHT
% HOLDER OR CONTRIBUTOR WILL BE LIABLE FOR ANY DIRECT, INDIRECT,
% INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING IN ANY WAY OUT OF THE USE
% OF THE PACKAGE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


:- module(timer,[timer_start/1,    % +ID
		 timer_stop/2,     % +ID,-Duration
		 timer_pause/1,    % +ID
		 timer_pause/2,    % +ID,-Duration
		 timer_resume/1,   % +ID
		 timer_elapsed/2,  % +ID, -Duration
		 timer_reset/1]).  % +ID
:- yap_flag(unknown,error).
:- style_check(single_var).

:- dynamic(timer/2).
:- dynamic(timer_paused/2).


timer_start(Name) :-
	(
	 timer(Name,_)
	->
	 throw(timer_already_started(timer_start(Name)));

	 statistics(walltime,[StartTime,_]),
	 assertz(timer(Name,StartTime))
	).

timer_start_forced(Name) :-
	retractall(timer(Name,_)),
	statistics(walltime,[StartTime,_]),
	assertz(timer(Name,StartTime)).

timer_stop(Name,Duration) :-
	(
	 retract(timer(Name,StartTime))
	->
	 statistics(walltime,[StopTime,_]),
	 Duration is StopTime-StartTime;

	 throw(timer_not_started(timer_stop(Name,Duration)))
	).

timer_pause(Name) :-
  (
   retract(timer(Name,StartTime))
  ->
   statistics(walltime,[StopTime,_]),
   Duration is StopTime-StartTime,
   assertz(timer_paused(Name,Duration));

   throw(timer_not_started(timer_pause(Name)))
  ).

timer_pause(Name, Duration) :-
  (
   retract(timer(Name,StartTime))
  ->
   statistics(walltime,[StopTime,_]),
   Duration is StopTime-StartTime,
   assertz(timer_paused(Name,Duration));

   throw(timer_not_started(timer_pause(Name)))
  ).

timer_resume(Name):-
	(
	 retract(timer_paused(Name,Duration))
	->
	 statistics(walltime,[ResumeTime,_]),
	 CorrectedStartTime is ResumeTime-Duration,
	 assertz(timer(Name,CorrectedStartTime));
	 
	 throw(timer_not_paused(timer_resume(Name)))
	).

timer_elapsed(Name,Duration) :-
	(
	 timer(Name,StartTime)
	->
	 statistics(walltime,[StopTime,_]),
	 Duration is StopTime-StartTime;

	 throw(timer_not_started(timer_elapsed(Name,Duration)))
	).

timer_reset(Name) :-
	retractall(timer(Name,_)),
	retractall(timer_paused(Name,_)).