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 java.util.Vector;
  
  import parser.visitor.*;
  import prism.PrismLangException;
  import prism.PrismUtils;
  
  // class to store list of formulas
  
  public class FormulaList extends ASTElement
  {
  	// Name/expression pairs to define formulas
  	private Vector<String> names;
  	private Vector<Expression> formulas;
  	// We also store an ExpressionIdent to match each name.
  	// This is to just to provide positional info.
  	private Vector<ExpressionIdent> nameIdents;
  
  	// Constructor
  
  	public FormulaList()
  	{
  		names = new Vector<String>();
  		formulas = new Vector<Expression>();
  		nameIdents = new Vector<ExpressionIdent>();
  	}
  
  	// Set methods
  
  	public void addFormula(ExpressionIdent n, Expression f)
  	{
  		names.addElement(n.getName());
  		formulas.addElement(f);
  		nameIdents.addElement(n);
  	}
  
  	public void setFormulaName(int i, ExpressionIdent n)
  	{
  		names.set(i, n.getName());
  		nameIdents.set(i, n);
  	}
  
  	public void setFormula(int i, Expression f)
  	{
  		formulas.set(i, f);
  	}
  
  	// Get methods
  
  	public int size()
  	{
  		return formulas.size();
  	}
  
  	public String getFormulaName(int i)
  	{
  		return names.elementAt(i);
  	}
  
  	public Expression getFormula(int i)
  	{
  		return formulas.elementAt(i);
  	}
  
  	public ExpressionIdent getFormulaNameIdent(int i)
  	{
  		return nameIdents.elementAt(i);
  	}
  
  	/**
  	 * Get the index of a formula by its name (returns -1 if it does not exist).
  	 */
  	public int getFormulaIndex(String s)
  	{
  		return names.indexOf(s);
  	}
  
  	/**
  	 * Find cyclic dependencies.
  	 */
  	public void findCycles() throws PrismLangException
  	{
  		// Create boolean matrix of dependencies
  		// (matrix[i][j] is true if formula i contains formula j)
  		int n = size();
  		boolean matrix[][] = new boolean[n][n];
  		for (int i = 0; i < n; i++) {
  			Vector<String> v = getFormula(i).getAllFormulas();
  			for (int j = 0; j < v.size(); j++) {
  				int k = getFormulaIndex((String) v.elementAt(j));
  				if (k != -1) {
  					matrix[i][k] = true;
  				}
  			}
  		}
  		// Check for and report dependencies
  		int firstCycle = PrismUtils.findCycle(matrix);
  		if (firstCycle != -1) {
  			String s = "Cyclic dependency in definition of formula \"" + getFormulaName(firstCycle) + "\"";
  			throw new PrismLangException(s, getFormula(firstCycle));
  		}
  	}
  
  	// Methods required for ASTElement:
  
  	/**
  	 * Visitor method.
  	 */
  	public Object accept(ASTVisitor v) throws PrismLangException
  	{
  		return v.visit(this);
  	}
  
  	/**
  	 * Convert to string.
  	 */
  	public String toString()
  	{
  		String s = "";
  		int i, n;
  
  		n = size();
  		for (i = 0; i < n; i++) {
  			s += "formula " + getFormulaName(i);
  			s += " = " + getFormula(i) + ";\n";
  		}
  
  		return s;
  	}
  
  	/**
  	 * Perform a deep copy.
  	 */
  	public ASTElement deepCopy()
  	{
  		int i, n;
  		FormulaList ret = new FormulaList();
  		n = size();
  		for (i = 0; i < n; i++) {
  			ret.addFormula((ExpressionIdent)getFormulaNameIdent(i).deepCopy(), getFormula(i).deepCopy());
  		}
  		ret.setPosition(this);
  		return ret;
  	}
  }
  
  // ------------------------------------------------------------------------------
  