1/* 2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26package com.sun.xml.internal.xsom.util; 27 28import java.util.ArrayList; 29import java.util.Collection; 30import java.util.Iterator; 31import java.util.List; 32import java.util.NoSuchElementException; 33 34/** 35 * {@link Collection} that returns the view of objects which are actually fetched 36 * lazily from an {@link Iterator}. 37 * 38 * @author Kohsuke Kawaguchi 39 */ 40public class DeferedCollection<T> implements Collection<T> { 41 /** 42 * The iterator that lazily evaluates SCD query. 43 */ 44 private final Iterator<T> result; 45 46 /** 47 * Stores values that are already fetched from {@link #result}. 48 */ 49 private final List<T> archive = new ArrayList<T>(); 50 51 public DeferedCollection(Iterator<T> result) { 52 this.result = result; 53 } 54 55 public boolean isEmpty() { 56 if(archive.isEmpty()) 57 fetch(); 58 return archive.isEmpty(); 59 } 60 61 public int size() { 62 fetchAll(); 63 return archive.size(); 64 } 65 66 public boolean contains(Object o) { 67 if(archive.contains(o)) 68 return true; 69 while(result.hasNext()) { 70 T value = result.next(); 71 archive.add(value); 72 if(value.equals(o)) 73 return true; 74 } 75 return false; 76 } 77 78 public boolean containsAll(Collection<?> c) { 79 for (Object o : c) { 80 if(!contains(o)) 81 return false; 82 } 83 return true; 84 } 85 86 public Iterator<T> iterator() { 87 return new Iterator<T>() { 88 int idx=0; 89 public boolean hasNext() { 90 if(idx<archive.size()) 91 return true; 92 return result.hasNext(); 93 } 94 95 public T next() { 96 if(idx==archive.size()) 97 fetch(); 98 if(idx==archive.size()) 99 throw new NoSuchElementException(); 100 return archive.get(idx++); 101 } 102 103 public void remove() { 104 // TODO 105 } 106 }; 107 } 108 109 public Object[] toArray() { 110 fetchAll(); 111 return archive.toArray(); 112 } 113 114 public <T>T[] toArray(T[] a) { 115 fetchAll(); 116 return archive.toArray(a); 117 } 118 119 120 121 private void fetchAll() { 122 while(result.hasNext()) 123 archive.add(result.next()); 124 } 125 126 /** 127 * Fetches another item from {@link 128 */ 129 private void fetch() { 130 if(result.hasNext()) 131 archive.add(result.next()); 132 } 133 134// mutation methods are unsupported 135 public boolean add(T o) { 136 throw new UnsupportedOperationException(); 137 } 138 139 public boolean remove(Object o) { 140 throw new UnsupportedOperationException(); 141 } 142 143 public boolean addAll(Collection<? extends T> c) { 144 throw new UnsupportedOperationException(); 145 } 146 147 public boolean removeAll(Collection<?> c) { 148 throw new UnsupportedOperationException(); 149 } 150 151 public boolean retainAll(Collection<?> c) { 152 throw new UnsupportedOperationException(); 153 } 154 155 public void clear() { 156 throw new UnsupportedOperationException(); 157 } 158} 159