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.visitor;
  
  import parser.ast.ExpressionFormula;
  import parser.ast.ExpressionFunc;
  import parser.ast.ExpressionIdent;
  import prism.PrismLangException;
  
  /**
   * Perform any required semantic checks. These are just simple checks on expressions, mostly.
   * For semantic checks on models and properties, specifically, see:
   * {@link parser.visitor.ModulesFileSemanticCheck} and {@link parser.visitor.PropertiesSemanticCheck}. 
   * These checks are done *before* any undefined constants have been defined.
   */
  public class SemanticCheck extends ASTTraverse
  {
  	public SemanticCheck()
  	{
  	}
  
  	public void visitPost(ExpressionFunc e) throws PrismLangException
  	{
  		// Check function name is valid
  		if (e.getNameCode() == -1) {
  			throw new PrismLangException("Unknown function \"" + e.getName() + "\"", e);
  		}
  		// Check num arguments
  		if (e.getNumOperands() < e.getMinArity()) {
  			throw new PrismLangException("Not enough arguments to \"" + e.getName() + "\" function", e);
  		}
  		if (e.getMaxArity() != -1 && e.getNumOperands() > e.getMaxArity()) {
  			throw new PrismLangException("Too many arguments to \"" + e.getName() + "\" function", e);
  		}
  	}
  
  	public void visitPost(ExpressionIdent e) throws PrismLangException
  	{
  		// By the time the expression is checked, this should
  		// have been converted to an ExpressionVar/ExpressionConstant/...
  		throw new PrismLangException("Undeclared identifier", e);
  	}
  
  	public void visitPost(ExpressionFormula e) throws PrismLangException
  	{
  		// This should have been defined or expanded by now
  		if (e.getDefinition() == null)
  			throw new PrismLangException("Unexpanded formula", e);
  	}
  }
  