code: //==============================================================================
  //
  //Copyright (c) 2014-
  //Authors:
  //	* Joachim Klein <klein@tcs.inf.tu-dresden.de> (TU Dresden)
  //	* Dave Parker <d.a.parker@cs.bham.ac.uk> (University of Birmingham/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 acceptance;
  
  import common.IterableBitSet;
  import jdd.JDD;
  import jdd.JDDNode;
  import jdd.JDDVars;
  import prism.PrismNotSupportedException;
  
  /**
   * A reachability acceptance condition (based on JDD state sets).
   * The acceptance is defined via a set of goal states and
   * has to be "upward-closed", i.e., once a goal state has been reached,
   * all successor states are goal states as well.
   */
  public class AcceptanceReachDD implements AcceptanceOmegaDD
  {
  	/** The goal states */
  	private JDDNode goalStates;
  
  	/**
  	 * Constructor, set goalStates.
  	 * Becomes owner of the references of goalStates.
  	 */
  	public AcceptanceReachDD(JDDNode goalStates)
  	{
  		this.goalStates = goalStates;
  	}
  	
  	/**
  	 * Constructor, from a BitSet-based AcceptanceReach.
  	 *
  	 * @param acceptance the BitSet-based acceptance condition
  	 * @param ddRowVars JDDVars of the row variables corresponding to the bits in the bit set
  	 */
  	public AcceptanceReachDD(AcceptanceReach acceptance, JDDVars ddRowVars)
  	{
  		goalStates = JDD.Constant(0);
  		// get BDD based on the goalState bit set
  		for (int i : IterableBitSet.getSetBits(acceptance.getGoalStates())) {
  			goalStates = JDD.SetVectorElement(goalStates, ddRowVars, i, 1.0);
  		}
  	}
  
  	/** Get a referenced copy of the state set of the goal states.
  	 * <br>[ REFS: <i>result</i>, DEREFS: <i>none</i> ]
  	 */
  	public JDDNode getGoalStates()
  	{
  		JDD.Ref(goalStates);
  		return goalStates;
  	}
  
  	/**
  	 * Set the goal states.
  	 * Becomes owner of the reference to goalStates.
  	 */
  	public void setGoalStates(JDDNode goalStates)
  	{
  		clear();
  		this.goalStates = goalStates;
  	}
  
  	@Override
  	public boolean isBSCCAccepting(JDDNode bscc_states)
  	{
  		return JDD.AreIntersecting(goalStates, bscc_states);
  	}
  
  	@Override
  	public AcceptanceReachDD clone()
  	{
  		return new AcceptanceReachDD(goalStates.copy());
  	}
  
  	@Override
  	public void intersect(JDDNode restrict)
  	{
  		goalStates = JDD.And(goalStates, restrict.copy());
  	}
  
  	@Override
  	public String getSizeStatistics()
  	{
  		return "one set of goal states";
  	}
  
  	@Override
  	public AcceptanceType getType()
  	{
  		return AcceptanceType.REACH;
  	}
  
  	@Override
  	public AcceptanceOmegaDD complement(AcceptanceType... allowedAcceptance) throws PrismNotSupportedException
  	{
  		if (AcceptanceType.contains(allowedAcceptance, AcceptanceType.RABIN)) {
  			return complementToRabin();
  		} else if (AcceptanceType.contains(allowedAcceptance, AcceptanceType.STREETT)) {
  			return complementToStreett();
  		} else if (AcceptanceType.contains(allowedAcceptance, AcceptanceType.GENERIC)) {
  			return complementToGeneric();
  		}
  		throw new PrismNotSupportedException("Can not complement " + getType() + " acceptance to a supported acceptance type");
  	}
  
  	/**
  	 * Get a Rabin acceptance condition that is the complement of this condition, i.e.,
  	 * any word that is accepted by this condition is rejected by the returned Rabin condition.
  	 * <br>
  	 * Relies on the fact that once the goal states have been reached, all subsequent states
  	 * are goal states.
  	 *
  	 * @return the complement Rabin acceptance condition
  	 */
  	public AcceptanceRabinDD complementToRabin()
  	{
  		AcceptanceRabinDD rabin = new AcceptanceRabinDD();
  		rabin.add(new AcceptanceRabinDD.RabinPairDD(goalStates.copy(), JDD.Constant(1)));
  		return rabin;
  	}
  
  	/**
  	 * Get a Streett acceptance condition that is the complement of this condition, i.e.,
  	 * any word that is accepted by this condition is rejected by the returned Streett condition.
  	 * <br>
  	 * Relies on the fact that once the goal states have been reached, all subsequent states
  	 * are goal states.
  	 *
  	 * @return the complement Streett acceptance condition
  	 */
  	public AcceptanceStreettDD complementToStreett()
  	{
  		AcceptanceStreettDD streett = new AcceptanceStreettDD();
  		streett.add(new AcceptanceStreettDD.StreettPairDD(goalStates.copy(), JDD.Constant(0)));
  		return streett;
  	}
  
  	@Override
  	public AcceptanceGenericDD toAcceptanceGeneric()
  	{
  		return new AcceptanceGenericDD(AcceptanceGeneric.ElementType.INF, goalStates.copy());
  	}
  
  	@Override
  	@Deprecated
  	public String getTypeAbbreviated() {
  		return getType().getNameAbbreviated();
  	}
  
  	@Override
  	@Deprecated
  	public String getTypeName() {
  		return getType().getName();
  	}
  
  	@Override
  	public void clear()
  	{
  		if (goalStates != null) {
  			JDD.Deref(goalStates);
  		}
  	}
  
  }
  