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// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
//
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package com.google.protobuf;

import static com.google.protobuf.Internal.checkNotNull;

import java.util.AbstractList;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

/**
 * {@code RepeatedFieldBuilder} implements a structure that a protocol message uses to hold a
 * repeated field of other protocol messages. It supports the classical use case of adding immutable
 * {@link Message}'s to the repeated field and is highly optimized around this (no extra memory
 * allocations and sharing of immutable arrays). 
* It also supports the additional use case of adding a {@link Message.Builder} to the repeated * field and deferring conversion of that {@code Builder} to an immutable {@code Message}. In this * way, it's possible to maintain a tree of {@code Builder}'s that acts as a fully read/write data * structure.
* 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} and {@code * RepeatedFieldBuilder} classes cache messages that were created so that messages only need to be * created when some change occurred in its builder or a builder for one of its descendants. * * @param the type of message for the field * @param the type of builder for the field * @param the common interface for the message and the builder * @author [email protected] (Jon Perlow) */ public class RepeatedFieldBuilder< MType extends GeneratedMessage, BType extends GeneratedMessage.Builder, IType extends MessageOrBuilder> implements GeneratedMessage.BuilderParent { // Parent to send changes to. private GeneratedMessage.BuilderParent parent; // List of messages. Never null. It may be immutable, in which case // isMessagesListMutable will be false. See note below. private List messages; // Whether messages is an mutable array that can be modified. private boolean isMessagesListMutable; // List of builders. May be null, in which case, no nested builders were // created. If not null, entries represent the builder for that index. private List> builders; // Here are the invariants for messages and builders: // 1. messages is never null and its count corresponds to the number of items // in the repeated field. // 2. If builders is non-null, messages and builders MUST always // contain the same number of items. // 3. Entries in either array can be null, but for any index, there MUST be // either a Message in messages or a builder in builders. // 4. If the builder at an index is non-null, the builder is // authoritative. This is the case where a Builder was set on the index. // Any message in the messages array MUST be ignored. // t. If the builder at an index is null, the message in the messages // list is authoritative. This is the case where a Message (not a Builder) // was set directly for an index. // Indicates that we've built a message and so we are now obligated // to dispatch dirty invalidations. See GeneratedMessage.BuilderListener. private boolean isClean; // A view of this builder that exposes a List interface of messages. This is // initialized on demand. This is fully backed by this object and all changes // are reflected in it. Access to any item converts it to a message if it // was a builder. private MessageExternalList externalMessageList; // A view of this builder that exposes a List interface of builders. This is // initialized on demand. This is fully backed by this object and all changes // are reflected in it. Access to any item converts it to a builder if it // was a message. private BuilderExternalList externalBuilderList; // A view of this builder that exposes a List interface of the interface // implemented by messages and builders. This is initialized on demand. This // is fully backed by this object and all changes are reflected in it. // Access to any item returns either a builder or message depending on // what is most efficient. private MessageOrBuilderExternalList externalMessageOrBuilderList; /** * Constructs a new builder with an empty list of messages. * * @param messages the current list of messages * @param isMessagesListMutable Whether the messages list is mutable * @param parent a listener to notify of changes * @param isClean whether the builder is initially marked clean */ public RepeatedFieldBuilder( List messages, boolean isMessagesListMutable, GeneratedMessage.BuilderParent parent, boolean isClean) { this.messages = messages; this.isMessagesListMutable = isMessagesListMutable; this.parent = parent; this.isClean = isClean; } public void dispose() { // Null out parent so we stop sending it invalidations. parent = null; } /** * Ensures that the list of messages is mutable so it can be updated. If it's immutable, a copy is * made. */ private void ensureMutableMessageList() { if (!isMessagesListMutable) { messages = new ArrayList(messages); isMessagesListMutable = true; } } /** * Ensures that the list of builders is not null. If it's null, the list is created and * initialized to be the same size as the messages list with null entries. */ private void ensureBuilders() { if (this.builders == null) { this.builders = new ArrayList>(messages.size()); for (int i = 0; i < messages.size(); i++) { builders.add(null); } } } /** * Gets the count of items in the list. * * @return the count of items in the list. */ public int getCount() { return messages.size(); } /** * Gets whether the list is empty. * * @return whether the list is empty */ public boolean isEmpty() { return messages.isEmpty(); } /** * Get the message at the specified index. If the message is currently stored as a {@code * Builder}, it is converted to a {@code Message} by calling {@link Message.Builder#buildPartial} * on it. * * @param index the index of the message to get * @return the message for the specified index */ public MType getMessage(int index) { return getMessage(index, false); } /** * Get the message at the specified index. If the message is currently stored as a {@code * Builder}, it is converted to a {@code Message} by calling {@link Message.Builder#buildPartial} * on it. * * @param index the index of the message to get * @param forBuild this is being called for build so we want to make sure we * SingleFieldBuilder.build to send dirty invalidations * @return the message for the specified index */ private MType getMessage(int index, boolean forBuild) { if (this.builders == null) { // We don't have any builders -- return the current Message. // This is the case where no builder was created, so we MUST have a // Message. return messages.get(index); } SingleFieldBuilder builder = builders.get(index); if (builder == null) { // We don't have a builder -- return the current message. // This is the case where no builder was created for the entry at index, // so we MUST have a message. return messages.get(index); } else { return forBuild ? builder.build() : builder.getMessage(); } } /** * Gets a builder for the specified index. If no builder has been created for that index, a * builder is created on demand by calling {@link Message#toBuilder}. * * @param index the index of the message to get * @return The builder for that index */ public BType getBuilder(int index) { ensureBuilders(); SingleFieldBuilder builder = builders.get(index); if (builder == null) { MType message = messages.get(index); builder = new SingleFieldBuilder(message, this, isClean); builders.set(index, builder); } return builder.getBuilder(); } /** * Gets the base class interface for the specified index. This may either be a builder or a * message. It will return whatever is more efficient. * * @param index the index of the message to get * @return the message or builder for the index as the base class interface */ @SuppressWarnings("unchecked") public IType getMessageOrBuilder(int index) { if (this.builders == null) { // We don't have any builders -- return the current Message. // This is the case where no builder was created, so we MUST have a // Message. return (IType) messages.get(index); } SingleFieldBuilder builder = builders.get(index); if (builder == null) { // We don't have a builder -- return the current message. // This is the case where no builder was created for the entry at index, // so we MUST have a message. return (IType) messages.get(index); } else { return builder.getMessageOrBuilder(); } } /** * Sets a message at the specified index replacing the existing item at that index. * * @param index the index to set. * @param message the message to set * @return the builder */ public RepeatedFieldBuilder setMessage(int index, MType message) { checkNotNull(message); ensureMutableMessageList(); messages.set(index, message); if (builders != null) { SingleFieldBuilder entry = builders.set(index, null); if (entry != null) { entry.dispose(); } } onChanged(); incrementModCounts(); return this; } /** * Appends the specified element to the end of this list. * * @param message the message to add * @return the builder */ public RepeatedFieldBuilder addMessage(MType message) { checkNotNull(message); ensureMutableMessageList(); messages.add(message); if (builders != null) { builders.add(null); } onChanged(); incrementModCounts(); return this; } /** * Inserts the specified message at the specified position in this list. Shifts the element * currently at that position (if any) and any subsequent elements to the right (adds one to their * indices). * * @param index the index at which to insert the message * @param message the message to add * @return the builder */ public RepeatedFieldBuilder addMessage(int index, MType message) { checkNotNull(message); ensureMutableMessageList(); messages.add(index, message); if (builders != null) { builders.add(index, null); } onChanged(); incrementModCounts(); return this; } /** * Appends all of the messages in the specified collection to the end of this list, in the order * that they are returned by the specified collection's iterator. * * @param values the messages to add * @return the builder */ public RepeatedFieldBuilder addAllMessages( Iterable values) { for (final MType value : values) { checkNotNull(value); } // If we can inspect the size, we can more efficiently add messages. int size = -1; if (values instanceof Collection) { final Collection collection = (Collection) values; if (collection.isEmpty()) { return this; } size = collection.size(); } ensureMutableMessageList(); if (size >= 0 && messages instanceof ArrayList) { ((ArrayList) messages).ensureCapacity(messages.size() + size); } for (MType value : values) { addMessage(value); } onChanged(); incrementModCounts(); return this; } /** * Appends a new builder to the end of this list and returns the builder. * * @param message the message to add which is the basis of the builder * @return the new builder */ public BType addBuilder(MType message) { ensureMutableMessageList(); ensureBuilders(); SingleFieldBuilder builder = new SingleFieldBuilder(message, this, isClean); messages.add(null); builders.add(builder); onChanged(); incrementModCounts(); return builder.getBuilder(); } /** * Inserts a new builder at the specified position in this list. Shifts the element currently at * that position (if any) and any subsequent elements to the right (adds one to their indices). * * @param index the index at which to insert the builder * @param message the message to add which is the basis of the builder * @return the builder */ public BType addBuilder(int index, MType message) { ensureMutableMessageList(); ensureBuilders(); SingleFieldBuilder builder = new SingleFieldBuilder(message, this, isClean); messages.add(index, null); builders.add(index, builder); onChanged(); incrementModCounts(); return builder.getBuilder(); } /** * Removes the element at the specified position in this list. Shifts any subsequent elements to * the left (subtracts one from their indices). * * @param index the index at which to remove the message */ public void remove(int index) { ensureMutableMessageList(); messages.remove(index); if (builders != null) { SingleFieldBuilder entry = builders.remove(index); if (entry != null) { entry.dispose(); } } onChanged(); incrementModCounts(); } /** Removes all of the elements from this list. The list will be empty after this call returns. */ public void clear() { messages = Collections.emptyList(); isMessagesListMutable = false; if (builders != null) { for (SingleFieldBuilder entry : builders) { if (entry != null) { entry.dispose(); } } builders = null; } onChanged(); incrementModCounts(); } /** * Builds the list of messages from the builder and returns them. * * @return an immutable list of messages */ public List build() { // Now that build has been called, we are required to dispatch // invalidations. isClean = true; if (!isMessagesListMutable && builders == null) { // We still have an immutable list and we never created a builder. return messages; } boolean allMessagesInSync = true; if (!isMessagesListMutable) { // We still have an immutable list. Let's see if any of them are out // of sync with their builders. for (int i = 0; i < messages.size(); i++) { Message message = messages.get(i); SingleFieldBuilder builder = builders.get(i); if (builder != null) { if (builder.build() != message) { allMessagesInSync = false; break; } } } if (allMessagesInSync) { // Immutable list is still in sync. return messages; } } // Need to make sure messages is up to date ensureMutableMessageList(); for (int i = 0; i < messages.size(); i++) { messages.set(i, getMessage(i, true)); } // We're going to return our list as immutable so we mark that we can // no longer update it. messages = Collections.unmodifiableList(messages); isMessagesListMutable = false; return messages; } /** * Gets a view of the builder as a list of messages. The returned list is live and will reflect * any changes to the underlying builder. * * @return the messages in the list */ public List getMessageList() { if (externalMessageList == null) { externalMessageList = new MessageExternalList(this); } return externalMessageList; } /** * Gets a view of the builder as a list of builders. This returned list is live and will reflect * any changes to the underlying builder. * * @return the builders in the list */ public List getBuilderList() { if (externalBuilderList == null) { externalBuilderList = new BuilderExternalList(this); } return externalBuilderList; } /** * Gets a view of the builder as a list of MessageOrBuilders. This returned list is live and will * reflect any changes to the underlying builder. * * @return the builders in the list */ public List getMessageOrBuilderList() { if (externalMessageOrBuilderList == null) { externalMessageOrBuilderList = new MessageOrBuilderExternalList(this); } return externalMessageOrBuilderList; } /** * 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 (isClean && parent != null) { parent.markDirty(); // Don't keep dispatching invalidations until build is called again. isClean = false; } } @Override public void markDirty() { onChanged(); } /** * Increments the mod counts so that an ConcurrentModificationException can be thrown if calling * code tries to modify the builder while its iterating the list. */ private void incrementModCounts() { if (externalMessageList != null) { externalMessageList.incrementModCount(); } if (externalBuilderList != null) { externalBuilderList.incrementModCount(); } if (externalMessageOrBuilderList != null) { externalMessageOrBuilderList.incrementModCount(); } } /** * Provides a live view of the builder as a list of messages. * * @param the type of message for the field * @param the type of builder for the field * @param the common interface for the message and the builder */ private static class MessageExternalList< MType extends GeneratedMessage, BType extends GeneratedMessage.Builder, IType extends MessageOrBuilder> extends AbstractList implements List { RepeatedFieldBuilder builder; MessageExternalList(RepeatedFieldBuilder builder) { this.builder = builder; } @Override public int size() { return this.builder.getCount(); } @Override public MType get(int index) { return builder.getMessage(index); } void incrementModCount() { modCount++; } } /** * Provides a live view of the builder as a list of builders. * * @param the type of message for the field * @param the type of builder for the field * @param the common interface for the message and the builder */ private static class BuilderExternalList< MType extends GeneratedMessage, BType extends GeneratedMessage.Builder, IType extends MessageOrBuilder> extends AbstractList implements List { RepeatedFieldBuilder builder; BuilderExternalList(RepeatedFieldBuilder builder) { this.builder = builder; } @Override public int size() { return this.builder.getCount(); } @Override public BType get(int index) { return builder.getBuilder(index); } void incrementModCount() { modCount++; } } /** * Provides a live view of the builder as a list of builders. * * @param the type of message for the field * @param the type of builder for the field * @param the common interface for the message and the builder */ private static class MessageOrBuilderExternalList< MType extends GeneratedMessage, BType extends GeneratedMessage.Builder, IType extends MessageOrBuilder> extends AbstractList implements List { RepeatedFieldBuilder builder; MessageOrBuilderExternalList(RepeatedFieldBuilder builder) { this.builder = builder; } @Override public int size() { return this.builder.getCount(); } @Override public IType get(int index) { return builder.getMessageOrBuilder(index); } void incrementModCount() { modCount++; } } }




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