code: //==============================================================================
  //	
  //	Copyright (c) 2014-
  //	Authors:
  //	* Joachim Klein <klein@tcs.inf.tu-dresden.de> (TU Dresden)
  //	
  //------------------------------------------------------------------------------
  //	
  //	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 java.io.PrintStream;
  import java.util.ArrayList;
  import java.util.BitSet;
  
  import prism.PrismException;
  import prism.PrismNotSupportedException;
  import jdd.JDDVars;
  
  /**
   * A Rabin acceptance condition (based on BitSet state sets).
   * This is a list of RabinPairs, which can be manipulated with the usual List interface.
   * <br>
   * Semantics: Each Rabin pair has a state set L and K and is accepting iff
   * L is not visited infinitely often and K is visited infinitely often:
   *   (F G !"L") & (G F "K").
   *
   * The Rabin condition is accepting if at least one of the pairs is accepting.
   */
  @SuppressWarnings("serial")
  public class AcceptanceRabin
         extends ArrayList<AcceptanceRabin.RabinPair>
         implements AcceptanceOmega
  {
  
  	/**
  	 * A pair in a Rabin acceptance condition, i.e., with
  	 *  (F G !"L")  &  (G F "K")
  	 **/
  	public static class RabinPair {
  		/** State set L (should be visited only finitely often) */
  		private BitSet L;
  
  		/** State set K (should be visited infinitely often) */
  		private BitSet K;
  
  		/**
  		 * Constructor with L and K state sets.
  		 *  (F G !"L")  &  (G F "K")
  		 */
  		public RabinPair(BitSet L, BitSet K) {
  			this.L = L;
  			this.K = K;
  		}
  
  		/** Get the state set L */
  		public BitSet getL()
  		{
  			return L;
  		}
  
  		/** Get the state set K */
  		public BitSet getK()
  		{
  			return K;
  		}
  
  		/** Returns true if the bottom strongly connected component
  		 * given by bscc_states is accepting for this pair.
  		 */
  		public boolean isBSCCAccepting(BitSet bscc_states)
  		{
  			if (L.intersects(bscc_states)) {
  				// there is some state in bscc_states that is
  				// forbidden by L
  				return false;
  			}
  
  			if (K.intersects(bscc_states)) {
  				// there is some state in bscc_states that is
  				// contained in K -> infinitely often visits to K
  				return true;
  			}
  
  			return false;
  		}
  
  		public AcceptanceGeneric toAcceptanceGeneric()
  		{
  			AcceptanceGeneric genericL = new AcceptanceGeneric(AcceptanceGeneric.ElementType.FIN, (BitSet)L.clone());
  			AcceptanceGeneric genericK = new AcceptanceGeneric(AcceptanceGeneric.ElementType.INF, (BitSet)K.clone());
  			
  			//      F G ! "L" & G F "K"
  			// <=>  Fin(L) & Inf(K)
  			return new AcceptanceGeneric(AcceptanceGeneric.ElementType.AND, genericL, genericK);
  		}
  
  		/** Generate signature for this Rabin pair and the given state.
  		 *  If the state is a member of L, returns "-pairIndex".
  		 *  If the state is a member of K, returns "+pairIndex".
  		 *  @param stateIndex the state index
  		 *  @param pairIndex the index of this Rabin pair
  		 **/
  		public String getSignatureForState(int stateIndex, int pairIndex)
  		{
  			if (L.get(stateIndex)) {
  				return "-"+pairIndex;
  			} else if (K.get(stateIndex)) {
  				return "+"+pairIndex;
  			} else {
  				return "";
  			}
  		}
  
  		@Override
  		public RabinPair clone()
  		{
  			return new RabinPair((BitSet)L.clone(), (BitSet)K.clone());
  		}
  
  		/** Returns a textual representation of this Rabin pair. */
  		@Override
  		public String toString() {
  			return "(" + L + "," + K + ")";
  		}
  	}
  
  	/** Make a copy of the acceptance condition. */
  	public AcceptanceRabin clone()
  	{
  		AcceptanceRabin result = new AcceptanceRabin();
  		for (RabinPair pair : this) {
  			result.add(pair.clone());
  		}
  
  		return result;
  	}
  
  	/** Returns true if the bottom strongly connected component
  	 * given by bscc_states is accepting for this Rabin condition,
  	 * i.e., there is a pair that accepts for bscc_states.
  	 */
  	public boolean isBSCCAccepting(BitSet bscc_states)
  	{
  		for (RabinPair pair : this) {
  			if (pair.isBSCCAccepting(bscc_states)) {
  				return true;
  			}
  		}
  
  		return false;
  	}
  
  	@Override
  	public void lift(LiftBitSet lifter) {
  		for (RabinPair pair : this) {
  			pair.L = lifter.lift(pair.L);
  			pair.K = lifter.lift(pair.K);
  		}
  	}
  
  	/**
  	 * Get the Streett acceptance condition that is the dual of this Rabin acceptance condition, i.e.,
  	 * any word that is accepted by this condition is rejected by the returned Streett condition.
  	 * @return the complement Streett acceptance condition
  	 */
  	public AcceptanceStreett complementToStreett()
  	{
  		AcceptanceStreett accStreett = new AcceptanceStreett();
  
  		for (RabinPair accPairRabin : this) {
  			BitSet R = (BitSet) accPairRabin.getK().clone();
  			BitSet G = (BitSet) accPairRabin.getL().clone();
  			AcceptanceStreett.StreettPair accPairStreett = new AcceptanceStreett.StreettPair(R, G);
  			accStreett.add(accPairStreett);
  		}
  
  		return accStreett;
  	}
  
  	/** Complement this acceptance condition, return as AcceptanceGeneric. */
  	public AcceptanceGeneric complementToGeneric()
  	{
  		return toAcceptanceGeneric().complementToGeneric();
  	}
  
  	@Override
  	public AcceptanceOmega complement(int numStates, AcceptanceType... allowedAcceptance) throws PrismException
  	{
  		if (AcceptanceType.contains(allowedAcceptance, AcceptanceType.STREETT)) {
  			return complementToStreett();
  		}
  		if (AcceptanceType.contains(allowedAcceptance, AcceptanceType.GENERIC)) {
  			return complementToGeneric();
  		}
  		throw new PrismNotSupportedException("Can not complement " + getType() + " acceptance to a supported acceptance type");
  	}
  
  	/**
  	 * Returns a new Rabin acceptance condition that corresponds to the disjunction
  	 * of this and the other Rabin acceptance condition. The RabinPairs are cloned, i.e.,
  	 * not shared with the argument acceptance condition.
  	 * @param other the other Rabin acceptance condition
  	 * @return new AcceptanceRabin, disjunction of this and other
  	 */
  	public AcceptanceRabin or(AcceptanceRabin other)
  	{
  		AcceptanceRabin result = new AcceptanceRabin();
  		for (RabinPair pair : this) {
  			result.add((RabinPair) pair.clone());
  		}
  		for (RabinPair pair : other) {
  			result.add((RabinPair) pair.clone());
  		}
  		return result;
  	}
  
  	@Override
  	public AcceptanceRabinDD toAcceptanceDD(JDDVars ddRowVars)
  	{
  		return new AcceptanceRabinDD(this, ddRowVars);
  	}
  
  	@Override
  	public AcceptanceGeneric toAcceptanceGeneric()
  	{
  		if (size() == 0) {
  			return new AcceptanceGeneric(false);
  		}
  		AcceptanceGeneric genericPairs = null;
  		for (RabinPair pair : this) {
  			AcceptanceGeneric genericPair = pair.toAcceptanceGeneric();
  			if (genericPairs == null) {
  				genericPairs = genericPair;
  			} else {
  				genericPairs = new AcceptanceGeneric(AcceptanceGeneric.ElementType.OR, genericPairs, genericPair);
  			}
  		}
  		return genericPairs;
  	}
  
  	/**
  	 * Get the acceptance signature for state stateIndex.
  	 **/
  	public String getSignatureForState(int stateIndex)
  	{
  		String result = "";
  
  		for (int pairIndex=0; pairIndex<size(); pairIndex++) {
  			RabinPair pair = get(pairIndex);
  			result += pair.getSignatureForState(stateIndex,  pairIndex);
  		}
  
  		return result;
  	}
  
  	@Override
  	public String getSignatureForStateHOA(int stateIndex)
  	{
  		String result = "";
  
  		for (int pairIndex=0; pairIndex<size(); pairIndex++) {
  			RabinPair pair = get(pairIndex);
  			if (pair.getL().get(stateIndex)) {
  				result += (result.isEmpty() ? "" : " ") + pairIndex*2;
  			}
  			if (pair.getK().get(stateIndex)) {
  				result += (result.isEmpty() ? "" : " ") + (pairIndex*2+1);
  			}
  		}
  
  		if (!result.isEmpty())
  			result = "{"+result+"}";
  
  		return result;
  	}
  
  	
  	/** Returns a textual representation of this acceptance condition. */
  	@Override
  	public String toString()
  	{
  		String result = "";
  		for (RabinPair pair : this) {
  			result += pair.toString();
  		}
  		return result;
  	}
  
  	@Override
  	public String getSizeStatistics()
  	{
  		return size() + " Rabin pairs";
  	}
  
  	@Override
  	public AcceptanceType getType()
  	{
  		return AcceptanceType.RABIN;
  	}
  
  	@Override
  	@Deprecated
  	public String getTypeAbbreviated() {
  		return getType().getNameAbbreviated();
  	}
  
  	@Override
  	@Deprecated
  	public String getTypeName() {
  		return getType().getName();
  	}
  
  	@Override
  	public void outputHOAHeader(PrintStream out)
  	{
  		out.println("acc-name: Rabin "+size());
  		out.print("Acceptance: " + (size()*2)+" ");
  		if (size() == 0) {
  			out.println("f");
  			return;
  		}
  
  		for (int pair = 0; pair < size(); pair++) {
  			if (pair > 0) out.print(" | ");
  			out.print("( Fin(" + 2*pair + ") & Inf(" + (2*pair+1) +") )");
  		}
  		out.println();
  	}
  }
  