package ca.ubc.cs.spl.aspectPatterns.examples.interpreter.java;
/* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* This file is part of the design patterns project at UBC
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* either http://www.mozilla.org/MPL/ or http://aspectj.org/MPL/.
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is ca.ubc.cs.spl.aspectPatterns.
*
* For more details and the latest version of this code, please see:
* http://www.cs.ubc.ca/labs/spl/projects/aodps.html
*
* Contributor(s):
*/
import java.util.Hashtable;
/**
* Implements a <i>Context</i> for the interpretation of boolean
* expressions<p>
*
* @author Jan Hannemann
* @author Gregor Kiczales
* @version 1.1, 02/11/04
*/
public class VariableContext {
/**
* stores the mapping between variable names and values
*/
protected Hashtable assignments = new Hashtable();
/**
* Returns the current value for a variable
*
* @param name the name of the variable
* @return the value of the variable
*/
public boolean lookup(String name) {
Boolean value = (Boolean) assignments.get(name);
if (value == null) {
throw new ExpressionException("No variable \""+name+"\" known.");
}
return value.booleanValue();
}
/**
* Assigns a boolean value to a <code>VariableExpression</code>
*
* @param varExp the varaible <i>Expression</i> to assign a value to
* @param bool the boolean value to assign
*/
public void assign(VariableExpression varExp, boolean bool) {
assignments.put(varExp.getName(), new Boolean(bool));
}
}