1/* 2 * Copyright (C) 2008 The Guava Authors 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.google.common.collect; 18 19import static com.google.common.base.Preconditions.checkNotNull; 20 21import java.io.Serializable; 22import java.util.AbstractCollection; 23import java.util.Collection; 24import java.util.Collections; 25import java.util.Iterator; 26 27import javax.annotation.Nullable; 28 29/** 30 * GWT emulated version of {@link ImmutableCollection}. 31 * 32 * @author Jesse Wilson 33 */ 34@SuppressWarnings("serial") // we're overriding default serialization 35public abstract class ImmutableCollection<E> extends AbstractCollection<E> 36 implements Serializable { 37 38 static final ImmutableCollection<Object> EMPTY_IMMUTABLE_COLLECTION 39 = new ForwardingImmutableCollection<Object>(Collections.emptyList()); 40 41 ImmutableCollection() {} 42 43 public abstract UnmodifiableIterator<E> iterator(); 44 45 public boolean contains(@Nullable Object object) { 46 return object != null && super.contains(object); 47 } 48 49 public final boolean add(E e) { 50 throw new UnsupportedOperationException(); 51 } 52 53 public final boolean remove(Object object) { 54 throw new UnsupportedOperationException(); 55 } 56 57 public final boolean addAll(Collection<? extends E> newElements) { 58 throw new UnsupportedOperationException(); 59 } 60 61 public final boolean removeAll(Collection<?> oldElements) { 62 throw new UnsupportedOperationException(); 63 } 64 65 public final boolean retainAll(Collection<?> elementsToKeep) { 66 throw new UnsupportedOperationException(); 67 } 68 69 public final void clear() { 70 throw new UnsupportedOperationException(); 71 } 72 73 private transient ImmutableList<E> asList; 74 75 public ImmutableList<E> asList() { 76 ImmutableList<E> list = asList; 77 return (list == null) ? (asList = createAsList()) : list; 78 } 79 80 ImmutableList<E> createAsList() { 81 switch (size()) { 82 case 0: 83 return ImmutableList.of(); 84 case 1: 85 return ImmutableList.of(iterator().next()); 86 default: 87 return new RegularImmutableAsList<E>(this, toArray()); 88 } 89 } 90 static <E> ImmutableCollection<E> unsafeDelegate(Collection<E> delegate) { 91 return new ForwardingImmutableCollection<E>(delegate); 92 } 93 94 boolean isPartialView() { 95 return false; 96 } 97 98 /** 99 * GWT emulated version of {@link ImmutableCollection.Builder}. 100 */ 101 public abstract static class Builder<E> { 102 103 Builder() {} 104 105 public abstract Builder<E> add(E element); 106 107 public Builder<E> add(E... elements) { 108 checkNotNull(elements); // for GWT 109 for (E element : elements) { 110 add(checkNotNull(element)); 111 } 112 return this; 113 } 114 115 public Builder<E> addAll(Iterable<? extends E> elements) { 116 checkNotNull(elements); // for GWT 117 for (E element : elements) { 118 add(checkNotNull(element)); 119 } 120 return this; 121 } 122 123 public Builder<E> addAll(Iterator<? extends E> elements) { 124 checkNotNull(elements); // for GWT 125 while (elements.hasNext()) { 126 add(checkNotNull(elements.next())); 127 } 128 return this; 129 } 130 131 public abstract ImmutableCollection<E> build(); 132 } 133} 134