| /******************************************************************************* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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.ofbiz.base.util.collections; |
| |
| import java.io.Serializable; |
| import java.util.AbstractSet; |
| import java.util.Iterator; |
| import java.util.LinkedList; |
| import java.util.EmptyStackException; |
| |
| /** |
| * LifoSet - Set interface wrapper around a LinkedList |
| * |
| */ |
| @SuppressWarnings("serial") |
| public class LifoSet<V> extends AbstractSet<V> implements Serializable { |
| |
| // This set's back LinkedList |
| private LinkedList<V> backedList = new LinkedList<V>(); |
| private int maxCapacity = 10; |
| |
| /** |
| * Constructs a set containing the elements of the specified |
| * collection, in the order they are returned by the collection's |
| * iterator. |
| */ |
| public LifoSet() {} |
| |
| /** |
| * Constructs a set containing the elements of the specified |
| * collection, in the order they are returned by the collection's |
| * iterator. |
| * |
| * @param capacity the collection whose elements are to be placed into this set. |
| */ |
| public LifoSet(int capacity) { |
| maxCapacity = capacity; |
| } |
| |
| /** |
| * Sets the max capacity for this LifoSet |
| * @param capacity Max Size (as integer) |
| */ |
| public void setCapactity(int capacity) { |
| this.maxCapacity = capacity; |
| } |
| |
| /** |
| * @see java.util.Collection#size() |
| */ |
| @Override |
| public int size() { |
| return backedList.size(); |
| } |
| |
| /** |
| * @see java.util.Collection#add(java.lang.Object) |
| */ |
| @Override |
| public boolean add(V obj) { |
| int index = backedList.indexOf(obj); |
| |
| if (index == -1) { |
| backedList.addFirst(obj); |
| while (size() > maxCapacity) |
| backedList.removeLast(); |
| } else { |
| backedList.remove(index); |
| backedList.addFirst(obj); |
| } |
| return true; |
| } |
| |
| /** |
| * @see java.util.Collection#iterator() |
| */ |
| @Override |
| public Iterator<V> iterator() { |
| return backedList.iterator(); |
| } |
| |
| // Stack Implementation (implements all Stack methods as per the java.util.Stack object |
| |
| /** |
| * @see java.util.Stack#empty() |
| * |
| * @return true if and only if this stack contains no items; false otherwise |
| */ |
| public boolean empty() { |
| if (this.size() == 0) { |
| return true; |
| } |
| return false; |
| } |
| |
| /** |
| * @see java.util.Stack#push(java.lang.Object) |
| * |
| * @param item The item to be pushed onto this stack |
| */ |
| public void push(V item) { |
| this.add(item); |
| } |
| |
| /** |
| * @see java.util.Stack#pop() |
| * |
| * @return The object at the top of this stack |
| * @throws EmptyStackException If this stack is empty |
| */ |
| public V pop() throws EmptyStackException { |
| if (this.size() > 0) { |
| return backedList.removeFirst(); |
| } |
| throw new EmptyStackException(); |
| } |
| |
| /** |
| * @see java.util.Stack#peek() |
| * |
| * @return The object at the top of this stack |
| * @throws EmptyStackException If this stack is empty |
| */ |
| public V peek() throws EmptyStackException { |
| if (this.size() > 0) { |
| return backedList.getFirst(); |
| } |
| throw new EmptyStackException(); |
| } |
| |
| /** |
| * @see java.util.Stack#search(java.lang.Object) |
| * |
| * @param item The desired object |
| * @return The 1-based position from the top of the stack where the object is located; |
| * the return value -1 indicates that the object is not on the stack |
| */ |
| public int search(Object item) { |
| int index = backedList.indexOf(item); |
| if (index > -1) { |
| return index + 1; // this method is 1 based (per java.util.Stack) |
| } |
| return -1; |
| } |
| } |
| |