code: //==============================================================================
  //	
  //	Copyright (c) 2002-
  //	Authors:
  //	* Dave Parker <david.parker@comlab.ox.ac.uk> (University of Oxford, formerly University of Birmingham)
  //	
  //------------------------------------------------------------------------------
  //	
  //	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 parser.ast;
  
  import param.BigRational;
  import parser.*;
  import parser.visitor.*;
  import prism.PrismLangException;
  
  public class ExpressionITE extends Expression
  {
  	// Operands
  	protected Expression operand1 = null; // condition
  	protected Expression operand2 = null; // then
  	protected Expression operand3 = null; // else
  
  	// Constructor
  
  	public ExpressionITE(Expression c, Expression t, Expression e)
  	{
  		operand1 = c;
  		operand2 = t;
  		operand3 = e;
  	}
  
  	// Set methods
  
  	public void setOperand1(Expression e)
  	{
  		operand1 = e;
  	}
  
  	public void setOperand2(Expression e)
  	{
  		operand2 = e;
  	}
  
  	public void setOperand3(Expression e)
  	{
  		operand3 = e;
  	}
  
  	// Get methods
  
  	public Expression getOperand1()
  	{
  		return operand1;
  	}
  
  	public Expression getOperand2()
  	{
  		return operand2;
  	}
  
  	public Expression getOperand3()
  	{
  		return operand3;
  	}
  
  	// Methods required for Expression:
  
  	@Override
  	public boolean isConstant()
  	{
  		return operand1.isConstant() && operand2.isConstant() && operand3.isConstant();
  	}
  
  	@Override
  	public boolean isProposition()
  	{
  		return operand1.isProposition() && operand2.isProposition() && operand3.isProposition();
  	}
  	
  	@Override
  	public Object evaluate(EvaluateContext ec) throws PrismLangException
  	{
  		return operand1.evaluateBoolean(ec) ? operand2.evaluate(ec) : operand3.evaluate(ec);
  	}
  
  	@Override
  	public BigRational evaluateExact(EvaluateContext ec) throws PrismLangException
  	{
  		return operand1.evaluateExact(ec).toBoolean() ? operand2.evaluateExact(ec) : operand3.evaluateExact(ec);
  	}
  
  	@Override
  	public boolean returnsSingleValue()
  	{
  		return operand1.returnsSingleValue() && operand2.returnsSingleValue() && operand3.returnsSingleValue();
  	}
  
  	// Methods required for ASTElement:
  
  	@Override
  	public Object accept(ASTVisitor v) throws PrismLangException
  	{
  		return v.visit(this);
  	}
  
  	@Override
  	public Expression deepCopy()
  	{
  		ExpressionITE expr = new ExpressionITE(operand1.deepCopy(), operand2.deepCopy(), operand3.deepCopy());
  		expr.setType(type);
  		expr.setPosition(this);
  		return expr;
  	}
  
  	// Standard methods
  	
  	@Override
  	public String toString()
  	{
  		return operand1 + " ? " + operand2 + " : " + operand3;
  	}
  
  	@Override
  	public int hashCode()
  	{
  		final int prime = 31;
  		int result = 1;
  		result = prime * result + ((operand1 == null) ? 0 : operand1.hashCode());
  		result = prime * result + ((operand2 == null) ? 0 : operand2.hashCode());
  		result = prime * result + ((operand3 == null) ? 0 : operand3.hashCode());
  		return result;
  	}
  
  	@Override
  	public boolean equals(Object obj)
  	{
  		if (this == obj)
  			return true;
  		if (obj == null)
  			return false;
  		if (getClass() != obj.getClass())
  			return false;
  		ExpressionITE other = (ExpressionITE) obj;
  		if (operand1 == null) {
  			if (other.operand1 != null)
  				return false;
  		} else if (!operand1.equals(other.operand1))
  			return false;
  		if (operand2 == null) {
  			if (other.operand2 != null)
  				return false;
  		} else if (!operand2.equals(other.operand2))
  			return false;
  		if (operand3 == null) {
  			if (other.operand3 != null)
  				return false;
  		} else if (!operand3.equals(other.operand3))
  			return false;
  		return true;
  	}
  }
  
  // ------------------------------------------------------------------------------
  