1 // Protocol Buffers - Google's data interchange format 2 // Copyright 2008 Google Inc. All rights reserved. 3 // https://developers.google.com/protocol-buffers/ 4 // 5 // Redistribution and use in source and binary forms, with or without 6 // modification, are permitted provided that the following conditions are 7 // met: 8 // 9 // * Redistributions of source code must retain the above copyright 10 // notice, this list of conditions and the following disclaimer. 11 // * Redistributions in binary form must reproduce the above 12 // copyright notice, this list of conditions and the following disclaimer 13 // in the documentation and/or other materials provided with the 14 // distribution. 15 // * Neither the name of Google Inc. nor the names of its 16 // contributors may be used to endorse or promote products derived from 17 // this software without specific prior written permission. 18 // 19 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 23 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 24 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 25 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 29 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 31 package com.google.protobuf; 32 33 import com.google.protobuf.Internal.ProtobufList; 34 35 import java.util.AbstractList; 36 import java.util.Collection; 37 import java.util.List; 38 import java.util.RandomAccess; 39 40 /** 41 * An abstract implementation of {@link ProtobufList} which manages mutability semantics. All mutate 42 * methods must check if the list is mutable before proceeding. Subclasses must invoke 43 * {@link #ensureIsMutable()} manually when overriding those methods. 44 * <p> 45 * This implementation assumes all subclasses are array based, supporting random access. 46 */ 47 abstract class AbstractProtobufList<E> extends AbstractList<E> implements ProtobufList<E> { 48 49 protected static final int DEFAULT_CAPACITY = 10; 50 51 /** 52 * Whether or not this list is modifiable. 53 */ 54 private boolean isMutable; 55 56 /** 57 * Constructs a mutable list by default. 58 */ AbstractProtobufList()59 AbstractProtobufList() { 60 isMutable = true; 61 } 62 63 @Override equals(Object o)64 public boolean equals(Object o) { 65 if (o == this) { 66 return true; 67 } 68 if (!(o instanceof List)) { 69 return false; 70 } 71 // Handle lists that do not support RandomAccess as efficiently as possible by using an iterator 72 // based approach in our super class. Otherwise our index based approach will avoid those 73 // allocations. 74 if (!(o instanceof RandomAccess)) { 75 return super.equals(o); 76 } 77 78 List<?> other = (List<?>) o; 79 final int size = size(); 80 if (size != other.size()) { 81 return false; 82 } 83 for (int i = 0; i < size; i++) { 84 if (!get(i).equals(other.get(i))) { 85 return false; 86 } 87 } 88 return true; 89 } 90 91 @Override hashCode()92 public int hashCode() { 93 final int size = size(); 94 int hashCode = 1; 95 for (int i = 0; i < size; i++) { 96 hashCode = (31 * hashCode) + get(i).hashCode(); 97 } 98 return hashCode; 99 } 100 101 @Override add(E e)102 public boolean add(E e) { 103 ensureIsMutable(); 104 return super.add(e); 105 } 106 107 @Override add(int index, E element)108 public void add(int index, E element) { 109 ensureIsMutable(); 110 super.add(index, element); 111 } 112 113 @Override addAll(Collection<? extends E> c)114 public boolean addAll(Collection<? extends E> c) { 115 ensureIsMutable(); 116 return super.addAll(c); 117 } 118 119 @Override addAll(int index, Collection<? extends E> c)120 public boolean addAll(int index, Collection<? extends E> c) { 121 ensureIsMutable(); 122 return super.addAll(index, c); 123 } 124 125 @Override clear()126 public void clear() { 127 ensureIsMutable(); 128 super.clear(); 129 } 130 131 @Override isModifiable()132 public boolean isModifiable() { 133 return isMutable; 134 } 135 136 @Override makeImmutable()137 public final void makeImmutable() { 138 isMutable = false; 139 } 140 141 @Override remove(int index)142 public E remove(int index) { 143 ensureIsMutable(); 144 return super.remove(index); 145 } 146 147 @Override remove(Object o)148 public boolean remove(Object o) { 149 ensureIsMutable(); 150 return super.remove(o); 151 } 152 153 @Override removeAll(Collection<?> c)154 public boolean removeAll(Collection<?> c) { 155 ensureIsMutable(); 156 return super.removeAll(c); 157 } 158 159 @Override retainAll(Collection<?> c)160 public boolean retainAll(Collection<?> c) { 161 ensureIsMutable(); 162 return super.retainAll(c); 163 } 164 165 @Override set(int index, E element)166 public E set(int index, E element) { 167 ensureIsMutable(); 168 return super.set(index, element); 169 } 170 171 /** 172 * Throws an {@link UnsupportedOperationException} if the list is immutable. Subclasses are 173 * responsible for invoking this method on mutate operations. 174 */ ensureIsMutable()175 protected void ensureIsMutable() { 176 if (!isMutable) { 177 throw new UnsupportedOperationException(); 178 } 179 } 180 } 181