| /******************************************************************************* |
| * Copyright (c) 2007 IBM Corporation and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| * |
| *******************************************************************************/ |
| package org.eclipse.jst.jsp.core.internal.java; |
| |
| import java.util.HashMap; |
| import java.util.Map; |
| import java.util.Stack; |
| |
| /** |
| * @author nitin |
| * |
| */ |
| class StackMap { |
| |
| private Map fInternalMap = null; |
| |
| public StackMap() { |
| fInternalMap = new HashMap(); |
| } |
| |
| /** |
| * Removes all mappings from this StackMap |
| */ |
| public void clear() { |
| fInternalMap.clear(); |
| } |
| |
| /** |
| * Returns the most recently pushed value to which this map maps the |
| * specified key. Returns <tt>null</tt> if the map contains no mapping |
| * for this key. |
| * |
| * @param key |
| * key whose associated value is to be returned. |
| * @return the most recently put value to which this map maps the |
| * specified key, or <tt>null</tt> if the map contains no |
| * mapping for this key. |
| */ |
| public Object peek(Object key) { |
| Stack stack = (Stack) fInternalMap.get(key); |
| if (stack != null) { |
| Object o = stack.peek(); |
| if (stack.isEmpty()) { |
| fInternalMap.remove(key); |
| } |
| return o; |
| } |
| return null; |
| } |
| |
| /** |
| * Associates the specified value with the specified key in this map. If |
| * the map previously contained a mapping for this key, the old value is |
| * pushed onto the top of this key's private stack. |
| * |
| * @param key |
| * key with which the specified value is to be associated. |
| * @param value |
| * value to be associated with the specified key. |
| * @return newest value associated with specified key |
| * |
| * @throws UnsupportedOperationException |
| * if the <tt>put</tt> operation is not supported by this |
| * StackMap. |
| * @throws ClassCastException |
| * if the class of the specified key or value prevents it from |
| * being stored in this StackMap. |
| * @throws IllegalArgumentException |
| * if some aspect of this key or value prevents it from being |
| * stored in this StackMap. |
| * @throws NullPointerException, |
| * as this map does not permit <tt>null</tt> keys or values |
| */ |
| public Object push(Object key, Object value) { |
| Stack stack = (Stack) fInternalMap.get(key); |
| if (stack == null) { |
| stack = new Stack(); |
| fInternalMap.put(key, stack); |
| } |
| Object o = stack.push(value); |
| return o; |
| } |
| |
| /** |
| * Removes the most-recent mapping for this key from this StackMap if it |
| * is present. |
| * |
| * <p> |
| * Returns the value to which the map previously associated the key, or |
| * <tt>null</tt> if the map contained no mapping for this key. The map |
| * will not contain a mapping for the specified key once the call returns. |
| * |
| * @param key |
| * key whose stack is to be popped |
| * @return most-recently pushed value associated with specified key, or |
| * <tt>null</tt> if there was no mapping for key. |
| * |
| * @throws ClassCastException |
| * if the key is of an inappropriate type for this map. |
| * @throws NullPointerException |
| * if the key is <tt>null</tt> as this class does not permit |
| * <tt>null</tt> keys |
| */ |
| public Object pop(Object key) { |
| Stack stack = (Stack) fInternalMap.get(key); |
| if (stack != null) { |
| Object o = stack.pop(); |
| if (stack.isEmpty()) { |
| fInternalMap.remove(key); |
| } |
| return o; |
| } |
| return null; |
| } |
| } |