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 explicit;
  
  import java.util.BitSet;
  
  import prism.PrismException;
  
  /**
   * Abstract base class for an SCC consumer that is only interested in
   * the bottom strongly-connected components (BSCCs). <br/>
   *
   * Intercepts the {@code notifyNextSCC()} call, checks whether the SCC
   * is a BSCC and calls {@code notifyNextBSCC()} if that is the case.
   */
  public abstract class SCCConsumerBSCCs extends SCCConsumerBitSet {
  
  	protected Model model;
  
  	/** Constructor */
  	public SCCConsumerBSCCs()
  	{
  		model = null;  // will be set by notifyStart call
  	}
  
  	public  void notifyStart(Model model)
  	{
  		this.model = model;
  	}
  
  	/**
  	 * Call-back function. Called upon discovery of a BSCC.
  	 */
  	public abstract void notifyNextBSCC(BitSet bscc) throws PrismException;
  
  	@Override
  	public void notifyNextSCC(BitSet scc) throws PrismException
  	{
  		boolean bottom = true;
  		// BSCC <=> for all states s, all successors are again in the SCC.
  		for (int s = scc.nextSetBit(0); s >= 0; s = scc.nextSetBit(s + 1)) {
  			if (!model.allSuccessorsInSet(s, scc)) {
  				bottom = false;
  				break;
  			}
  		}
  
  		if (bottom) {
  			notifyNextBSCC(scc);
  		}
  	}
  }
  