code: //==============================================================================
  //	
  //	Copyright (c) 2002-
  //	Authors:
  //	* Dave Parker <david.parker@comlab.ox.ac.uk> (University of Oxford, formerly University of Birmingham)
  //	* Christian von Essen <christian.vonessen@imag.fr> (VERIMAG)
  //	* 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 jdd;
  
  public class JDDNode
  {
  	private long ptr;
  	
  	// native methods (jni)
  	protected static native boolean DDN_IsConstant(long dd);
  	protected static native int DDN_GetIndex(long dd);
  	protected static native double DDN_GetValue(long dd);
  	protected static native long DDN_GetThen(long dd);
  	protected static native long DDN_GetElse(long dd);
  
  	static
  	{
  		try {
  			System.loadLibrary("jdd");
  		}
  		catch (UnsatisfiedLinkError e) {
  			System.out.println(e);
  			System.exit(1);
  		}
  	}
  
  	/**
  	 * Protected constructor from a DdNode pointer.
  	 * In general, to get a JDDNode from a pointer,
  	 * use JDD.ptrToNode().
  	 */
  	protected JDDNode(long p)
  	{
  		ptr = p;
  	}
  	
  	public long ptr()
  	{
  		return ptr;
  	}
  
  	public boolean isConstant()
  	{
  		return DDN_IsConstant(ptr);
  	}
  
  	public int getIndex()
  	{	
  		return DDN_GetIndex(ptr);
  	}
  
  	public double getValue()
  	{
  		if (DebugJDD.debugEnabled) {
  			return DebugJDD.nodeGetValue(this);
  		}
  		return DDN_GetValue(ptr);
  	}
  
  	/**
  	 * Returns the Then child of a (non-constant) JDDNode.
  	 * <br>
  	 * This method does NOT increase the reference count of the returned
  	 * node, it is therefore illegal to call JDD.Deref on the result.
  	 * Additionally, it is recommended to not use the returned node
  	 * as the argument to the JDD methods or call JDD.Ref on it.
  	 * Instead, if you need to obtain a "proper" node, call copy()
  	 * on the returned node.
  	 * <br>[ REFS: <i>none</i>, DEREFS: <i>none</i> ]
  	 */
  	public JDDNode getThen()
  	{
  		if (DebugJDD.debugEnabled) {
  			return DebugJDD.nodeGetThen(this);
  		}
  
  		long thenPtr = DDN_GetThen(ptr);
  		if (thenPtr == 0) {
  			if (isConstant()) {
  				throw new RuntimeException("Trying to access the 'then' child of a constant MTBDD node");
  			} else {
  				throw new RuntimeException("getThen: CUDD returned NULL, but node is not a constant node. Out of memory or corrupted MTBDD?");
  			}
  		}
  		return new JDDNode(thenPtr);
  	}
  
  	/**
  	 * Returns the Else child of a (non-constant) JDDNode.
  	 * <br>
  	 * This method does NOT increase the reference count of the returned
  	 * node, it is therefore illegal to call JDD.Deref on the result.
  	 * Additionally, it is recommended to not use the returned node
  	 * as the argument to the JDD methods or call JDD.Ref on it.
  	 * Instead, if you need to obtain a "proper" node, call copy()
  	 * on the returned node.
  	 * <br>[ REFS: <i>none</i>, DEREFS: <i>none</i> ]
  	 */
  	public JDDNode getElse()
  	{
  		if (DebugJDD.debugEnabled) {
  			return DebugJDD.nodeGetElse(this);
  		}
  
  		long elsePtr = DDN_GetElse(ptr);
  		if (elsePtr == 0) {
  			if (isConstant()) {
  				throw new RuntimeException("Trying to access the 'else' child of a constant MTBDD node");
  			} else {
  				throw new RuntimeException("getElse: CUDD returned NULL, but node is not a constant node. Out of memory or corrupted MTBDD?");
  			}
  		}
  		return new JDDNode(elsePtr);
  	}
  
  	public boolean equals(Object o)
  	{
  		return (o instanceof JDDNode) && (((JDDNode) o).ptr == ptr);
  	}
  	
  	public int hashCode()
  	{
  		return (int)ptr; 
  	}
  	
  	public String toString()
  	{
  		String result = "" + ptr;
  		if (ptr != 0) {
  			if (this.isConstant()) result += " value=" + this.getValue();
  			result += " references=" + DebugJDD.getRefCount(this);
  		}
  		return result;
  	}
  
  	/**
  	 * Returns a referenced copy of this node.
  	 * This has the effect of increasing the reference count
  	 * for the underlying MTBDD.
  	 * <br>[ REFS: <i>result</i>, DEREFS: <i>none</i> ]
  	 */
  	public JDDNode copy()
  	{
  		if (DebugJDD.debugEnabled) {
  			return DebugJDD.Copy(this);
  		} else {
  			JDDNode result = new JDDNode(ptr());
  			JDD.Ref(result);
  			return result;
  		}
  	}
  }
  
  //------------------------------------------------------------------------------
  