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| 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 /** | |
| 34 * {@code SingleFieldBuilderV3} implements a structure that a protocol | |
| 35 * message uses to hold a single field of another protocol message. It supports | |
| 36 * the classical use case of setting an immutable {@link Message} as the value | |
| 37 * of the field and is highly optimized around this. | |
| 38 * <br> | |
| 39 * It also supports the additional use case of setting a {@link Message.Builder} | |
| 40 * as the field and deferring conversion of that {@code Builder} | |
| 41 * to an immutable {@code Message}. In this way, it's possible to maintain | |
| 42 * a tree of {@code Builder}'s that acts as a fully read/write data | |
| 43 * structure. | |
| 44 * <br> | |
| 45 * Logically, one can think of a tree of builders as converting the entire tree | |
| 46 * to messages when build is called on the root or when any method is called | |
| 47 * that desires a Message instead of a Builder. In terms of the implementation, | |
| 48 * the {@code SingleFieldBuilderV3} and {@code RepeatedFieldBuilderV3} | |
| 49 * classes cache messages that were created so that messages only need to be | |
| 50 * created when some change occurred in its builder or a builder for one of its | |
| 51 * descendants. | |
| 52 * | |
| 53 * @param <MType> the type of message for the field | |
| 54 * @param <BType> the type of builder for the field | |
| 55 * @param <IType> the common interface for the message and the builder | |
| 56 * | |
| 57 * @author jonp@google.com (Jon Perlow) | |
| 58 */ | |
| 59 public class SingleFieldBuilderV3 | |
| 60 <MType extends AbstractMessage, | |
| 61 BType extends AbstractMessage.Builder, | |
| 62 IType extends MessageOrBuilder> | |
| 63 implements AbstractMessage.BuilderParent { | |
| 64 | |
| 65 // Parent to send changes to. | |
| 66 private AbstractMessage.BuilderParent parent; | |
| 67 | |
| 68 // Invariant: one of builder or message fields must be non-null. | |
| 69 | |
| 70 // If set, this is the case where we are backed by a builder. In this case, | |
| 71 // message field represents a cached message for the builder (or null if | |
| 72 // there is no cached message). | |
| 73 private BType builder; | |
| 74 | |
| 75 // If builder is non-null, this represents a cached message from the builder. | |
| 76 // If builder is null, this is the authoritative message for the field. | |
| 77 private MType message; | |
| 78 | |
| 79 // Indicates that we've built a message and so we are now obligated | |
| 80 // to dispatch dirty invalidations. See AbstractMessage.BuilderListener. | |
| 81 private boolean isClean; | |
| 82 | |
| 83 public SingleFieldBuilderV3( | |
| 84 MType message, | |
| 85 AbstractMessage.BuilderParent parent, | |
| 86 boolean isClean) { | |
| 87 if (message == null) { | |
| 88 throw new NullPointerException(); | |
| 89 } | |
| 90 this.message = message; | |
| 91 this.parent = parent; | |
| 92 this.isClean = isClean; | |
| 93 } | |
| 94 | |
| 95 public void dispose() { | |
| 96 // Null out parent so we stop sending it invalidations. | |
| 97 parent = null; | |
| 98 } | |
| 99 | |
| 100 /** | |
| 101 * Get the message for the field. If the message is currently stored | |
| 102 * as a {@code Builder}, it is converted to a {@code Message} by | |
| 103 * calling {@link Message.Builder#buildPartial} on it. If no message has | |
| 104 * been set, returns the default instance of the message. | |
| 105 * | |
| 106 * @return the message for the field | |
| 107 */ | |
| 108 @SuppressWarnings("unchecked") | |
| 109 public MType getMessage() { | |
| 110 if (message == null) { | |
| 111 // If message is null, the invariant is that we must be have a builder. | |
| 112 message = (MType) builder.buildPartial(); | |
| 113 } | |
| 114 return message; | |
| 115 } | |
| 116 | |
| 117 /** | |
| 118 * Builds the message and returns it. | |
| 119 * | |
| 120 * @return the message | |
| 121 */ | |
| 122 public MType build() { | |
| 123 // Now that build has been called, we are required to dispatch | |
| 124 // invalidations. | |
| 125 isClean = true; | |
| 126 return getMessage(); | |
| 127 } | |
| 128 | |
| 129 /** | |
| 130 * Gets a builder for the field. If no builder has been created yet, a | |
| 131 * builder is created on demand by calling {@link Message#toBuilder}. | |
| 132 * | |
| 133 * @return The builder for the field | |
| 134 */ | |
| 135 @SuppressWarnings("unchecked") | |
| 136 public BType getBuilder() { | |
| 137 if (builder == null) { | |
| 138 // builder.mergeFrom() on a fresh builder | |
| 139 // does not create any sub-objects with independent clean/dirty states, | |
| 140 // therefore setting the builder itself to clean without actually calling | |
| 141 // build() cannot break any invariants. | |
| 142 builder = (BType) message.newBuilderForType(this); | |
| 143 builder.mergeFrom(message); // no-op if message is the default message | |
| 144 builder.markClean(); | |
| 145 } | |
| 146 return builder; | |
| 147 } | |
| 148 | |
| 149 /** | |
| 150 * Gets the base class interface for the field. This may either be a builder | |
| 151 * or a message. It will return whatever is more efficient. | |
| 152 * | |
| 153 * @return the message or builder for the field as the base class interface | |
| 154 */ | |
| 155 @SuppressWarnings("unchecked") | |
| 156 public IType getMessageOrBuilder() { | |
| 157 if (builder != null) { | |
| 158 return (IType) builder; | |
| 159 } else { | |
| 160 return (IType) message; | |
| 161 } | |
| 162 } | |
| 163 | |
| 164 /** | |
| 165 * Sets a message for the field replacing any existing value. | |
| 166 * | |
| 167 * @param message the message to set | |
| 168 * @return the builder | |
| 169 */ | |
| 170 public SingleFieldBuilderV3<MType, BType, IType> setMessage( | |
| 171 MType message) { | |
| 172 if (message == null) { | |
| 173 throw new NullPointerException(); | |
| 174 } | |
| 175 this.message = message; | |
| 176 if (builder != null) { | |
| 177 builder.dispose(); | |
| 178 builder = null; | |
| 179 } | |
| 180 onChanged(); | |
| 181 return this; | |
| 182 } | |
| 183 | |
| 184 /** | |
| 185 * Merges the field from another field. | |
| 186 * | |
| 187 * @param value the value to merge from | |
| 188 * @return the builder | |
| 189 */ | |
| 190 public SingleFieldBuilderV3<MType, BType, IType> mergeFrom( | |
| 191 MType value) { | |
| 192 if (builder == null && message == message.getDefaultInstanceForType()) { | |
| 193 message = value; | |
| 194 } else { | |
| 195 getBuilder().mergeFrom(value); | |
| 196 } | |
| 197 onChanged(); | |
| 198 return this; | |
| 199 } | |
| 200 | |
| 201 /** | |
| 202 * Clears the value of the field. | |
| 203 * | |
| 204 * @return the builder | |
| 205 */ | |
| 206 @SuppressWarnings("unchecked") | |
| 207 public SingleFieldBuilderV3<MType, BType, IType> clear() { | |
| 208 message = (MType) (message != null ? | |
| 209 message.getDefaultInstanceForType() : | |
| 210 builder.getDefaultInstanceForType()); | |
| 211 if (builder != null) { | |
| 212 builder.dispose(); | |
| 213 builder = null; | |
| 214 } | |
| 215 onChanged(); | |
| 216 return this; | |
| 217 } | |
| 218 | |
| 219 /** | |
| 220 * Called when a the builder or one of its nested children has changed | |
| 221 * and any parent should be notified of its invalidation. | |
| 222 */ | |
| 223 private void onChanged() { | |
| 224 // If builder is null, this is the case where onChanged is being called | |
| 225 // from setMessage or clear. | |
| 226 if (builder != null) { | |
| 227 message = null; | |
| 228 } | |
| 229 if (isClean && parent != null) { | |
| 230 parent.markDirty(); | |
| 231 | |
| 232 // Don't keep dispatching invalidations until build is called again. | |
| 233 isClean = false; | |
| 234 } | |
| 235 } | |
| 236 | |
| 237 @Override | |
| 238 public void markDirty() { | |
| 239 onChanged(); | |
| 240 } | |
| 241 } | |
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Chromium Code Reviews
Issue 2590803003:
Revert "third_party/protobuf: Update to HEAD (83d681ee2c)" (Closed)
