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//==============================================================================
//
// Copyright (c) 2002-
// Authors:
// * Dave Parker <david.parker@comlab.ox.ac.uk> (University of Oxford)
//
//------------------------------------------------------------------------------
//
// This file is part of PRISM.
//
// PRISM 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.
//
// PRISM 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 General Public License
// along with PRISM; if not, write to the Free Software Foundation,
// Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
//==============================================================================
package simulator.sampler;
import simulator.*;
import prism.*;
import parser.ast.*;
public class SamplerRewardReach extends SamplerDouble
{
private Expression target;
private int rewardStructIndex;
/**
* Construct a sampler for a reachability reward property.
* Passed in ExpressionTemporal should be a property of this type.
* Reward structure index should also be specified.
* All constants should have already been evaluated/replaced.
*/
public SamplerRewardReach(ExpressionTemporal expr, int rewardStructIndex) throws PrismException
{
// If the answer is already known we should do nothing
if (valueKnown)
return;
// Make sure expression is of the correct type
// Then extract other required info
if (expr.getOperator() != ExpressionTemporal.P_F)
throw new PrismException("Error creating Sampler");
target = expr.getOperand2();
this.rewardStructIndex = rewardStructIndex;
// Initialise sampler info
reset();
resetStats();
}
@Override
public boolean update(Path path, TransitionList transList) throws PrismLangException
{
// If the answer is already known we should do nothing
if (valueKnown)
return true;
if (target.evaluateBoolean(path.getCurrentState())) {
valueKnown = true;
value = path.getTotalCumulativeReward(rewardStructIndex);
}
return valueKnown;
}
}