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 all constants, return result.
   */
  public class ExpandConstants extends ASTTraverseModify
  {
  	private ConstantList constantList;
  	
  	public ExpandConstants(ConstantList constantList)
  	{
  		this.constantList = constantList;
  	}
  	
  	public Object visit(ExpressionConstant e) throws PrismLangException
  	{
  		int i;
  		Type t;
  		Expression expr;
  		
  		// See if identifier corresponds to a constant
  		i = constantList.getConstantIndex(e.getName());
  		if (i != -1) {
  			// And check that the constant is defined
  			if (constantList.getConstant(i) != null) {
  				// If so, replace it with the corresponding expression
  				expr = constantList.getConstant(i).deepCopy();
  				// But also recursively expand that
  				expr = (Expression) expr.expandConstants(constantList);
  				// Put in brackets so precedence is preserved
  				// (for display purposes only; in case of re-parse)
  				// This is being done after type-checking so also set type
  				t = expr.getType();
  				expr = Expression.Parenth(expr);
  				expr.setType(t);
  				// Return replacement expression
  				return expr;
  			}
  			else {
  				// Error (should never happen)
  				throw new PrismLangException("Undefined constant", e);
  			}
  		}
  		else {
  			// Error (should never happen)
  			throw new PrismLangException("Undefined constant", e);
  		}
  	}
  }
  
  