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A useful utility library for java programmer using google protobuf.
/*
* Copyright 2002-2007 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// 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.baidu.bjf.remoting.protobuf;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import com.google.protobuf.Message;
/**
* Internal representation of map fields in generated messages.
*
* This class supports accessing the map field as a {@link Map} to be used in generated API and also supports accessing
* the field as a {@link List} to be used in reflection API. It keeps track of where the data is currently stored and do
* necessary conversions between map and list.
*
* This class is a protobuf implementation detail. Users shouldn't use this class directly.
*
* THREAD-SAFETY NOTE: Read-only access is thread-safe. Users can call getMap() and getList() concurrently in multiple
* threads. If write-access is needed, all access must be synchronized.
*
* @param the key type
* @param the value type
*/
public class MapField {
/**
* Indicates where the data of this map field is currently stored.
*
* MAP: Data is stored in mapData. LIST: Data is stored in listData. BOTH: mapData and listData have the same data.
*
* When the map field is accessed (through generated API or reflection API), it will shift between these 3 modes:
*
* getMap() getList() getMutableMap() getMutableList() MAP MAP BOTH MAP LIST LIST BOTH LIST MAP LIST BOTH BOTH BOTH
* MAP LIST
*
* As the map field changes its mode, the list/map reference returned in a previous method call may be invalidated.
*/
private enum StorageMode {
/** The map. */
MAP,
/** The list. */
LIST,
/** The both. */
BOTH
}
/** The mode. */
private volatile StorageMode mode;
/** The map data. */
private Map mapData;
/** The list data. */
private List listData;
/**
* The Interface Converter.
*
* @param the key type
* @param the value type
*/
// Convert between a map entry Message and a key-value pair.
private static interface Converter {
/**
* Convert key and value to message.
*
* @param key the key
* @param value the value
* @return the message
*/
Message convertKeyAndValueToMessage(K key, V value);
/**
* Convert message to key and value.
*
* @param message the message
* @param map the map
*/
void convertMessageToKeyAndValue(Message message, Map map);
/**
* Gets the message default instance.
*
* @return the message default instance
*/
Message getMessageDefaultInstance();
}
/**
* The Class ImmutableMessageConverter.
*
* @param the key type
* @param the value type
*/
private static class ImmutableMessageConverter implements Converter {
/** The default entry. */
private final MapEntry defaultEntry;
/**
* Instantiates a new immutable message converter.
*
* @param defaultEntry the default entry
*/
public ImmutableMessageConverter(MapEntry defaultEntry) {
this.defaultEntry = defaultEntry;
}
/*
* (non-Javadoc)
*
* @see com.baidu.bjf.remoting.protobuf.MapField.Converter#convertKeyAndValueToMessage(java.lang.Object,
* java.lang.Object)
*/
public Message convertKeyAndValueToMessage(K key, V value) {
return defaultEntry.newBuilderForType().setKey(key).setValue(value).buildPartial();
}
/*
* (non-Javadoc)
*
* @see
* com.baidu.bjf.remoting.protobuf.MapField.Converter#convertMessageToKeyAndValue(com.google.protobuf.Message,
* java.util.Map)
*/
public void convertMessageToKeyAndValue(Message message, Map map) {
MapEntry entry = (MapEntry) message;
map.put(entry.getKey(), entry.getValue());
}
/*
* (non-Javadoc)
*
* @see com.baidu.bjf.remoting.protobuf.MapField.Converter#getMessageDefaultInstance()
*/
public Message getMessageDefaultInstance() {
return defaultEntry;
}
}
/** The converter. */
private final Converter converter;
/**
* Instantiates a new map field.
*
* @param converter the converter
* @param mode the mode
* @param mapData the map data
* @param listData the list data
*/
private MapField(Converter converter, StorageMode mode, Map mapData, List listData) {
this.converter = converter;
this.mode = mode;
this.mapData = mapData;
this.listData = listData;
}
/**
* Instantiates a new map field.
*
* @param defaultEntry the default entry
* @param mode the mode
* @param mapData the map data
* @param listData the list data
*/
private MapField(MapEntry defaultEntry, StorageMode mode, Map mapData, List listData) {
this(new ImmutableMessageConverter(defaultEntry), mode, mapData, listData);
}
/**
* Returns an immutable empty MapField.
*
* @param the key type
* @param the value type
* @param defaultEntry the default entry
* @return the map field
*/
public static MapField emptyMapField(MapEntry defaultEntry) {
return new MapField(defaultEntry, StorageMode.MAP, Collections. emptyMap(), null);
}
/**
* Creates a new mutable empty MapField.
*
* @param the key type
* @param the value type
* @param defaultEntry the default entry
* @return the map field
*/
public static MapField newMapField(MapEntry defaultEntry) {
return new MapField(defaultEntry, StorageMode.MAP, new HashMap(), null);
}
/**
* Convert key and value to message.
*
* @param key the key
* @param value the value
* @return the message
*/
private Message convertKeyAndValueToMessage(K key, V value) {
return converter.convertKeyAndValueToMessage(key, value);
}
/**
* Convert message to key and value.
*
* @param message the message
* @param map the map
*/
@SuppressWarnings("unchecked")
private void convertMessageToKeyAndValue(Message message, Map map) {
converter.convertMessageToKeyAndValue(message, map);
}
/**
* Convert map to list.
*
* @param mapData the map data
* @return the list
*/
private List convertMapToList(Map mapData) {
List listData = new ArrayList();
for (Map.Entry entry : mapData.entrySet()) {
listData.add(convertKeyAndValueToMessage(entry.getKey(), entry.getValue()));
}
return listData;
}
/**
* Convert list to map.
*
* @param listData the list data
* @return the map
*/
private Map convertListToMap(List listData) {
Map mapData = new HashMap();
for (Message item : listData) {
convertMessageToKeyAndValue(item, mapData);
}
return mapData;
}
/**
* Gets the map.
*
* @return the map
*/
public Map getMap() {
if (mode == StorageMode.LIST) {
synchronized (this) {
if (mode == StorageMode.LIST) {
mapData = convertListToMap(listData);
mode = StorageMode.BOTH;
}
}
}
return Collections.unmodifiableMap(mapData);
}
/**
* Gets the mutable map.
*
* @return the mutable map
*/
public Map getMutableMap() {
if (mode != StorageMode.MAP) {
if (mode == StorageMode.LIST) {
mapData = convertListToMap(listData);
}
listData = null;
mode = StorageMode.MAP;
}
return mapData;
}
/**
* Merge from.
*
* @param other the other
*/
public void mergeFrom(MapField other) {
getMutableMap().putAll(MapFieldLite.copy(other.getMap()));
}
/**
* Clear.
*/
public void clear() {
mapData = new HashMap();
mode = StorageMode.MAP;
}
/*
* (non-Javadoc)
*
* @see java.lang.Object#equals(java.lang.Object)
*/
@SuppressWarnings("unchecked")
@Override
public boolean equals(Object object) {
if (!(object instanceof MapField)) {
return false;
}
MapField other = (MapField) object;
return MapFieldLite. equals(getMap(), other.getMap());
}
/*
* (non-Javadoc)
*
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode() {
return MapFieldLite. calculateHashCodeForMap(getMap());
}
/**
* Returns a deep copy of this MapField.
*
* @return the map field
*/
public MapField copy() {
return new MapField(converter, StorageMode.MAP, MapFieldLite.copy(getMap()), null);
}
/**
* Gets the list.
*
* @return the list
*/
List getList() {
if (mode == StorageMode.MAP) {
synchronized (this) {
if (mode == StorageMode.MAP) {
listData = convertMapToList(mapData);
mode = StorageMode.BOTH;
}
}
}
return Collections.unmodifiableList(listData);
}
/**
* Gets the mutable list.
*
* @return the mutable list
*/
List getMutableList() {
if (mode != StorageMode.LIST) {
if (mode == StorageMode.MAP) {
listData = convertMapToList(mapData);
}
mapData = null;
mode = StorageMode.LIST;
}
return listData;
}
/**
* Gets the map entry message default instance.
*
* @return the map entry message default instance
*/
Message getMapEntryMessageDefaultInstance() {
return converter.getMessageDefaultInstance();
}
}