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.visitor;
  
  import parser.ast.*;
  import parser.type.*;
  import prism.PrismLangException;
  
  /**
   * Expand property references and labels, return result.
   * Property expansion is done recursively.
   * Either properties file or label list can be omitted (set to null)
   * Special labels "deadlock", "init" and any not in label list are left.
   */
  public class ExpandPropRefsAndLabels extends ASTTraverseModify
  {
  	// The PropertiesFile for property lookup
  	private PropertiesFile propertiesFile;
  	// The LabelList for label definitions
  	private LabelList labelList;
  	
  	public ExpandPropRefsAndLabels(PropertiesFile propertiesFile, LabelList labelList)
  	{
  		this.propertiesFile = propertiesFile;
  		this.labelList = labelList;
  	}
  	
  	public Object visit(ExpressionLabel e) throws PrismLangException
  	{
  		int i;
  		Type t;
  		Expression expr;
  		
  		// Skip this if label list is missing
  		if (labelList == null) {
  			return e;
  		}
  		
  		// See if identifier corresponds to a label
  		i = labelList.getLabelIndex(e.getName());
  		if (i != -1) {
  			// If so, replace it with (a copy of) the corresponding expression
  			expr = labelList.getLabel(i).deepCopy();
  			// But also recursively expand that
  			// (nested labels not currently supported but may be one day)
  			// (don't clone it to avoid duplication of work)
  			expr = (Expression) expr.accept(this);
  			// Put in brackets so precedence is preserved
  			// (for display purposes only; in case of re-parse)
  			// Also, preserve type (this is probably being done before
  			// type-checking so unnecessary, but do so just in case)
  			t = expr.getType();
  			expr = Expression.Parenth(expr);
  			expr.setType(t);
  			// Return replacement expression
  			return expr;
  		}
  		
  		// Couldn't find definition - leave unchanged.
  		return e;
  	}
  
  	public Object visit(ExpressionProp e) throws PrismLangException
  	{
  		Property prop;
  		Type t;
  		Expression expr;
  		
  		// Skip this if label list is missing
  		if (propertiesFile == null) {
  			return e;
  		}
  		
  		// See if name corresponds to a property
  		prop = propertiesFile.lookUpPropertyObjectByName(e.getName());
  		if (prop != null) {
  			// If so, replace it with (a copy of) the corresponding expression
  			expr = prop.getExpression().deepCopy();
  			// But also recursively expand that
  			// (don't clone it to avoid duplication of work)
  			expr = (Expression) expr.accept(this);
  			// Put in brackets so precedence is preserved
  			// (for display purposes only; in case of re-parse)
  			// Also, preserve type (this is probably being done before
  			// type-checking so unnecessary, but do so just in case)
  			t = expr.getType();
  			expr = Expression.Parenth(expr);
  			expr.setType(t);
  			// Return replacement expression
  			return expr;
  		}
  		
  		// Couldn't find definition - leave unchanged.
  		return e;
  	}
  }
  
  