scriptsymboltable.java

Bean Scripting Framework (BSF)为在java应用中使用脚本语言

/*
 * Copyright 2004,2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.bsf.util;

import java.util.Hashtable;

/**
 * An <code>ScriptSymbolTable</code> object is used by a <code>CodeBuffer</code>
 * object to implement nested scopes.
 * 
 * @author   Matthew J. Duftler
 */
class ScriptSymbolTable extends Hashtable
{
	private Hashtable parentTable;

	ScriptSymbolTable(Hashtable parentTable)
  {
  	this.parentTable = parentTable;
  }
  public synchronized Object get(Object key)
  {
  	Object ret = super.get(key);

  	if (ret == null && parentTable != null)
  	  ret = parentTable.get(key);

  	return ret;
  }
}