| /** |
| * 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.apache.kahadb.util; |
| |
| import java.util.ArrayList; |
| |
| /** |
| * Provides a list of LinkedNode objects. |
| * |
| * @author chirino |
| */ |
| public class LinkedNodeList<T extends LinkedNode<T>> { |
| |
| T head; |
| int size; |
| |
| public LinkedNodeList() { |
| } |
| |
| public boolean isEmpty() { |
| return head == null; |
| } |
| |
| public void addLast(T node) { |
| node.linkToTail(this); |
| } |
| |
| public void addFirst(T node) { |
| node.linkToHead(this); |
| } |
| |
| public T getHead() { |
| return head; |
| } |
| |
| public T getTail() { |
| return head.prev; |
| } |
| |
| public void clear() { |
| while (head != null) { |
| head.unlink(); |
| } |
| } |
| |
| public void addLast(LinkedNodeList<T> list) { |
| if (list.isEmpty()) { |
| return; |
| } |
| if (head == null) { |
| head = list.head; |
| reparent(list); |
| } else { |
| getTail().linkAfter(list); |
| } |
| } |
| |
| public void addFirst(LinkedNodeList<T> list) { |
| if (list.isEmpty()) { |
| return; |
| } |
| if (head == null) { |
| reparent(list); |
| head = list.head; |
| list.head = null; |
| } else { |
| getHead().linkBefore(list); |
| } |
| } |
| |
| public T reparent(LinkedNodeList<T> list) { |
| size += list.size; |
| T n = list.head; |
| do { |
| n.list = this; |
| n = n.next; |
| } while (n != list.head); |
| list.head = null; |
| list.size = 0; |
| return n; |
| } |
| |
| /** |
| * Move the head to the tail and returns the new head node. |
| * |
| * @return |
| */ |
| public T rotate() { |
| if( head ==null ) |
| return null; |
| return head = head.getNextCircular(); |
| } |
| |
| /** |
| * Move the head to the tail and returns the new head node. |
| * |
| * @return |
| */ |
| public void rotateTo(T head) { |
| assert head!=null: "Cannot rotate to a null head"; |
| assert head.list == this : "Cannot rotate to a node not linked to this list"; |
| this.head = head; |
| } |
| |
| public int size() { |
| return size; |
| } |
| |
| @Override |
| public String toString() { |
| StringBuilder sb = new StringBuilder(); |
| sb.append("["); |
| boolean first=true; |
| T cur = getHead(); |
| while( cur!=null ) { |
| if( !first ) { |
| sb.append(", "); |
| } |
| sb.append(cur); |
| first=false; |
| cur = cur.getNext(); |
| } |
| sb.append("]"); |
| return sb.toString(); |
| } |
| |
| /** |
| * Copies the nodes of the LinkedNodeList to an ArrayList. |
| * @return |
| */ |
| public ArrayList<T> toArrayList() { |
| ArrayList<T> rc = new ArrayList<T>(size); |
| T cur = head; |
| while( cur!=null ) { |
| rc.add(cur); |
| cur = cur.getNext(); |
| } |
| return rc; |
| } |
| } |