/*
 * Env.java
 * Copyright (C) 2006, Bjorn Bringert (bringert@cs.chalmers.se)
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package se.chalmers.cs.gf.transfer;

import java.util.*;
import se.chalmers.cs.gf.GFException;

public class Env  {

    private Env parent = null;

	private Map<String,Value> map = new HashMap<String,Value>();

	public Env() {
	}

	public Env(Env env) {
	    this.parent = env;
	}

	public void add(String name, Value value) {
		map.put(name, value);
	}

	public void addAll(Env env) {
		map.putAll(env.map);
	}

	public Value lookup(String name) {
		Value v = map.get(name);
		if (v == null) {
		    if (parent != null)
			return parent.lookup(name);
		    else 
			throw new GFException("Variable " + name
				+ " not in environment " + this);
		}
		return v;
	}

	public String toString() {
		return parent + map.toString();
	}
	
}