1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.gallery3d.util;
18
19
20public class LinkedNode {
21    private LinkedNode mPrev;
22    private LinkedNode mNext;
23
24    public LinkedNode() {
25        mPrev = mNext = this;
26    }
27
28    public void insert(LinkedNode node) {
29        node.mNext = mNext;
30        mNext.mPrev = node;
31        node.mPrev = this;
32        mNext = node;
33    }
34
35    public void remove() {
36        if (mNext == this) throw new IllegalStateException();
37        mPrev.mNext = mNext;
38        mNext.mPrev = mPrev;
39        mPrev = mNext = null;
40    }
41
42    @SuppressWarnings("unchecked")
43    public static class List<T extends LinkedNode> {
44        private LinkedNode mHead = new LinkedNode();
45
46        public void insertLast(T node) {
47            mHead.mPrev.insert(node);
48        }
49
50        public T getFirst() {
51            return (T) (mHead.mNext == mHead ? null : mHead.mNext);
52        }
53
54        public T getLast() {
55            return (T) (mHead.mPrev == mHead ? null : mHead.mPrev);
56        }
57
58        public T nextOf(T node) {
59            return (T) (node.mNext == mHead ? null : node.mNext);
60        }
61
62        public T previousOf(T node) {
63            return (T) (node.mPrev == mHead ? null : node.mPrev);
64        }
65
66    }
67
68    public static <T extends LinkedNode> List<T> newList() {
69        return new List<T>();
70    }
71}
72