code: //==============================================================================
  //	
  //	Copyright (c) 2002-
  //	Authors:
  //	* 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 parser.ast;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import param.BigRational;
  import parser.EvaluateContext;
  import parser.visitor.ASTVisitor;
  import prism.PrismLangException;
  
  /**
   * Class to represent ATL &lt;&lt;.&gt;&gt; and [[.]] operators, i.e. quantification over strategies
   * ("there exists a strategy" or "for all strategies").
   */
  public class ExpressionStrategy extends Expression
  {
  	/** "There exists a strategy" (true) or "for all strategies" (false) */
  	protected boolean thereExists = false;
  	
  	/** Coalition info (for game models) */
  	protected Coalition coalition = new Coalition(); 
  	
  	/** Child expression(s) */
  	protected List<Expression> operands = new ArrayList<Expression>();
  	
  	/** Is there just a single operand (P/R operator)? If not, the operand list will be parenthesised. **/
  	protected boolean singleOperand = false;
  	
  	// Constructors
  
  	public ExpressionStrategy()
  	{
  	}
  
  	public ExpressionStrategy(boolean thereExists)
  	{
  		this.thereExists = thereExists;
  	}
  
  	public ExpressionStrategy(boolean thereExists, Expression expression)
  	{
  		this.thereExists = thereExists;
  		operands.add(expression);
  		singleOperand = true;
  	}
  
  	// Set methods
  
  	public void setThereExists(boolean thereExists)
  	{
  		this.thereExists = thereExists;
  	}
  	
  	public void setCoalitionAllPlayers()
  	{
  		this.coalition.setAllPlayers();
  	}
  
  	public void setCoalition(List<String> coalition)
  	{
  		this.coalition.setPlayers(coalition);
  	}
  
  	public void setSingleOperand(Expression expression)
  	{
  		operands.clear();
  		operands.add(expression);
  		singleOperand = true;
  	}
  
  	public void addOperand(Expression e)
  	{
  		operands.add(e);
  	}
  
  	public void setOperand(int i, Expression e)
  	{
  		operands.set(i, e);
  	}
  
  	// Get methods
  
  	public boolean isThereExists()
  	{
  		return thereExists;
  	}
  
  	/**
  	 * Get a string ""&lt;&lt;&gt;&gt;"" or "[[]]" indicating type of quantification.
  	 */
  	public String getOperatorString()
  	{
  		return thereExists ? "<<>>" : "[[]]";
  	}
  
  	public Coalition getCoalition()
  	{
  		return coalition;
  	}
  	
  	public boolean coalitionIsAllPlayers()
  	{
  		return coalition.isAllPlayers();
  	}
  	
  	public List<String> getCoalitionPlayers()
  	{
  		return coalition.getPlayers();
  	}
  	
  	public boolean hasSingleOperand()
  	{
  		return singleOperand;
  	}
  	
  	public int getNumOperands()
  	{
  		return operands.size();
  	}
  
  	public Expression getOperand(int i)
  	{
  		return operands.get(i);
  	}
  
  	public List<Expression> getOperands()
  	{
  		return operands;
  	}
  
  	// Methods required for Expression:
  
  	@Override
  	public boolean isConstant()
  	{
  		return false;
  	}
  
  	@Override
  	public boolean isProposition()
  	{
  		return false;
  	}
  
  	@Override
  	public Object evaluate(EvaluateContext ec) throws PrismLangException
  	{
  		throw new PrismLangException("Cannot evaluate a " + getOperatorString() + " operator without a model");
  	}
  
  	@Override
  	public BigRational evaluateExact(EvaluateContext ec) throws PrismLangException
  	{
  		throw new PrismLangException("Cannot evaluate a " + getOperatorString() + " operator without a model");
  	}
  
  	/*@Override
  	public String getResultName()
  	{
  		return expression.getResultName();
  	}*/
  
  	@Override
  	public boolean returnsSingleValue()
  	{
  		return false;
  	}
  
  	// Methods required for ASTElement:
  
  	@Override
  	public Object accept(ASTVisitor v) throws PrismLangException
  	{
  		return v.visit(this);
  	}
  
  	@Override
  	public Expression deepCopy()
  	{
  		ExpressionStrategy expr = new ExpressionStrategy();
  		expr.setThereExists(isThereExists());
  		expr.coalition = new Coalition(coalition);
  		for (Expression operand : operands) {
  			expr.addOperand((Expression) operand.deepCopy());
  		}
  		expr.singleOperand = singleOperand;
  		expr.setType(type);
  		expr.setPosition(this);
  		return expr;
  	}
  
  	// Standard methods
  
  	@Override
  	public String toString()
  	{
  		String s = "";
  		s += (thereExists ? "<<" : "[[");
  		s += coalition;
  		s += (thereExists ? ">> " : "]] ");
  		if (singleOperand) {
  			s += operands.get(0);
  		} else {
  			s += "(";
  			boolean first = true;
  			for (Expression operand : operands) {
  				if (!first)
  					s += ", ";
  				else
  					first = false;
  				s = s + operand;
  			}
  			s += ")";
  		}
  		return s;
  	}
  
  	@Override
  	public int hashCode()
  	{
  		final int prime = 31;
  		int result = 1;
  		result = prime * result + ((coalition == null) ? 0 : coalition.hashCode());
  		result = prime * result + ((operands == null) ? 0 : operands.hashCode());
  		result = prime * result + (singleOperand ? 1231 : 1237);
  		result = prime * result + (thereExists ? 1231 : 1237);
  		return result;
  	}
  
  	@Override
  	public boolean equals(Object obj)
  	{
  		if (this == obj)
  			return true;
  		if (obj == null)
  			return false;
  		if (getClass() != obj.getClass())
  			return false;
  		ExpressionStrategy other = (ExpressionStrategy) obj;
  		if (coalition == null) {
  			if (other.coalition != null)
  				return false;
  		} else if (!coalition.equals(other.coalition))
  			return false;
  		if (operands == null) {
  			if (other.operands != null)
  				return false;
  		} else if (!operands.equals(other.operands))
  			return false;
  		if (singleOperand != other.singleOperand)
  			return false;
  		if (thereExists != other.thereExists)
  			return false;
  		return true;
  	}
  }
  