/thirdparty/breakpad/third_party/protobuf/protobuf/java/src/main/java/com/google/protobuf/SingleFieldBuilder.java
http://github.com/tomahawk-player/tomahawk · Java · 241 lines · 100 code · 19 blank · 122 comment · 26 complexity · aea9087da5867b8e265dfae3eeba8da0 MD5 · raw file
- // Protocol Buffers - Google's data interchange format
- // Copyright 2008 Google Inc. All rights reserved.
- // http://code.google.com/p/protobuf/
- //
- // Redistribution and use in source and binary forms, with or without
- // modification, are permitted provided that the following conditions are
- // met:
- //
- // * Redistributions of source code must retain the above copyright
- // notice, this list of conditions and the following disclaimer.
- // * Redistributions in binary form must reproduce the above
- // copyright notice, this list of conditions and the following disclaimer
- // in the documentation and/or other materials provided with the
- // distribution.
- // * Neither the name of Google Inc. nor the names of its
- // contributors may be used to endorse or promote products derived from
- // this software without specific prior written permission.
- //
- // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- package com.google.protobuf;
- /**
- * <code>SingleFieldBuilder</code> implements a structure that a protocol
- * message uses to hold a single field of another protocol message. It supports
- * the classical use case of setting an immutable {@link Message} as the value
- * of the field and is highly optimized around this.
- * <br>
- * It also supports the additional use case of setting a {@link Message.Builder}
- * as the field and deferring conversion of that <code>Builder</code>
- * to an immutable <code>Message</code>. In this way, it's possible to maintain
- * a tree of <code>Builder</code>'s that acts as a fully read/write data
- * structure.
- * <br>
- * Logically, one can think of a tree of builders as converting the entire tree
- * to messages when build is called on the root or when any method is called
- * that desires a Message instead of a Builder. In terms of the implementation,
- * the <code>SingleFieldBuilder</code> and <code>RepeatedFieldBuilder</code>
- * classes cache messages that were created so that messages only need to be
- * created when some change occured in its builder or a builder for one of its
- * descendants.
- *
- * @param <MType> the type of message for the field
- * @param <BType> the type of builder for the field
- * @param <IType> the common interface for the message and the builder
- *
- * @author jonp@google.com (Jon Perlow)
- */
- public class SingleFieldBuilder
- <MType extends GeneratedMessage,
- BType extends GeneratedMessage.Builder,
- IType extends MessageOrBuilder>
- implements GeneratedMessage.BuilderParent {
- // Parent to send changes to.
- private GeneratedMessage.BuilderParent parent;
- // Invariant: one of builder or message fields must be non-null.
- // If set, this is the case where we are backed by a builder. In this case,
- // message field represents a cached message for the builder (or null if
- // there is no cached message).
- private BType builder;
- // If builder is non-null, this represents a cached message from the builder.
- // If builder is null, this is the authoritative message for the field.
- private MType message;
- // Indicates that we've built a message and so we are now obligated
- // to dispatch dirty invalidations. See GeneratedMessage.BuilderListener.
- private boolean isClean;
- public SingleFieldBuilder(
- MType message,
- GeneratedMessage.BuilderParent parent,
- boolean isClean) {
- if (message == null) {
- throw new NullPointerException();
- }
- this.message = message;
- this.parent = parent;
- this.isClean = isClean;
- }
- public void dispose() {
- // Null out parent so we stop sending it invalidations.
- parent = null;
- }
- /**
- * Get the message for the field. If the message is currently stored
- * as a <code>Builder</code>, it is converted to a <code>Message</code> by
- * calling {@link Message.Builder#buildPartial} on it. If no message has
- * been set, returns the default instance of the message.
- *
- * @return the message for the field
- */
- @SuppressWarnings("unchecked")
- public MType getMessage() {
- if (message == null) {
- // If message is null, the invariant is that we must be have a builder.
- message = (MType) builder.buildPartial();
- }
- return message;
- }
- /**
- * Builds the message and returns it.
- *
- * @return the message
- */
- public MType build() {
- // Now that build has been called, we are required to dispatch
- // invalidations.
- isClean = true;
- return getMessage();
- }
- /**
- * Gets a builder for the field. If no builder has been created yet, a
- * builder is created on demand by calling {@link Message#toBuilder}.
- *
- * @return The builder for the field
- */
- @SuppressWarnings("unchecked")
- public BType getBuilder() {
- if (builder == null) {
- // builder.mergeFrom() on a fresh builder
- // does not create any sub-objects with independent clean/dirty states,
- // therefore setting the builder itself to clean without actually calling
- // build() cannot break any invariants.
- builder = (BType) message.newBuilderForType(this);
- builder.mergeFrom(message); // no-op if message is the default message
- builder.markClean();
- }
- return builder;
- }
- /**
- * Gets the base class interface for the field. This may either be a builder
- * or a message. It will return whatever is more efficient.
- *
- * @return the message or builder for the field as the base class interface
- */
- @SuppressWarnings("unchecked")
- public IType getMessageOrBuilder() {
- if (builder != null) {
- return (IType) builder;
- } else {
- return (IType) message;
- }
- }
- /**
- * Sets a message for the field replacing any existing value.
- *
- * @param message the message to set
- * @return the builder
- */
- public SingleFieldBuilder<MType, BType, IType> setMessage(
- MType message) {
- if (message == null) {
- throw new NullPointerException();
- }
- this.message = message;
- if (builder != null) {
- builder.dispose();
- builder = null;
- }
- onChanged();
- return this;
- }
- /**
- * Merges the field from another field.
- *
- * @param value the value to merge from
- * @return the builder
- */
- public SingleFieldBuilder<MType, BType, IType> mergeFrom(
- MType value) {
- if (builder == null && message == message.getDefaultInstanceForType()) {
- message = value;
- } else {
- getBuilder().mergeFrom(value);
- }
- onChanged();
- return this;
- }
- /**
- * Clears the value of the field.
- *
- * @return the builder
- */
- @SuppressWarnings("unchecked")
- public SingleFieldBuilder<MType, BType, IType> clear() {
- message = (MType) (message != null ?
- message.getDefaultInstanceForType() :
- builder.getDefaultInstanceForType());
- if (builder != null) {
- builder.dispose();
- builder = null;
- }
- onChanged();
- return this;
- }
- /**
- * Called when a the builder or one of its nested children has changed
- * and any parent should be notified of its invalidation.
- */
- private void onChanged() {
- // If builder is null, this is the case where onChanged is being called
- // from setMessage or clear.
- if (builder != null) {
- message = null;
- }
- if (isClean && parent != null) {
- parent.markDirty();
- // Don't keep dispatching invalidations until build is called again.
- isClean = false;
- }
- }
- //@Override (Java 1.6 override semantics, but we must support 1.5)
- public void markDirty() {
- onChanged();
- }
- }