001/*
002 * (C) Copyright 2010 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 *     Anahide Tchertchian
018 */
019package org.nuxeo.ecm.platform.smart.query;
020
021import java.util.LinkedList;
022
023/**
024 * Linked list with a capacity to handle undo/redo actions.
025 * <p>
026 * The method {@link #addLast(Object)} will remove the first object of the list when at full capacity.
027 *
028 * @since 5.4
029 * @author Anahide Tchertchian
030 */
031public class HistoryList<E> extends LinkedList<E> {
032
033    private static final long serialVersionUID = 1L;
034
035    protected int capacity;
036
037    public HistoryList(int capacity) {
038        super();
039        this.capacity = capacity;
040    }
041
042    @Override
043    public void addLast(E o) {
044        if (size() >= capacity) {
045            removeFirst();
046        }
047        super.addLast(o);
048    }
049
050}