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A useful utility library for java programmer using google protobuf.
/*
* Copyright (c) Baidu Inc. All rights reserved.
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
package com.baidu.bjf.remoting.protobuf;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;
import com.google.protobuf.Internal;
import com.google.protobuf.Internal.EnumLite;
/**
* Internal representation of map fields in generated lite-runtime messages.
*
* This class is a protobuf implementation detail. Users shouldn't use this class directly.
*
* @param the key type
* @param the value type
*/
public final class MapFieldLite extends LinkedHashMap {
/** The is mutable. */
private boolean isMutable;
/**
* Instantiates a new map field lite.
*/
private MapFieldLite() {
this.isMutable = true;
}
/**
* Instantiates a new map field lite.
*
* @param mapData the map data
*/
private MapFieldLite(Map mapData) {
super(mapData);
this.isMutable = true;
}
/** The Constant EMPTY_MAP_FIELD. */
@SuppressWarnings({ "rawtypes", "unchecked" })
private static final MapFieldLite EMPTY_MAP_FIELD = new MapFieldLite(Collections.emptyMap());
static {
EMPTY_MAP_FIELD.makeImmutable();
}
/**
* Returns an singleton immutable empty MapFieldLite instance.
*
* @param the key type
* @param the value type
* @return the map field lite
*/
@SuppressWarnings({ "unchecked", "cast" })
public static MapFieldLite emptyMapField() {
return (MapFieldLite) EMPTY_MAP_FIELD;
}
/**
* Merge from.
*
* @param other the other
*/
public void mergeFrom(MapFieldLite other) {
ensureMutable();
if (!other.isEmpty()) {
putAll(other);
}
}
/* (non-Javadoc)
* @see java.util.HashMap#entrySet()
*/
@SuppressWarnings({ "unchecked", "cast" })
@Override
public Set> entrySet() {
return isEmpty() ? Collections.> emptySet() : super.entrySet();
}
/* (non-Javadoc)
* @see java.util.LinkedHashMap#clear()
*/
@Override
public void clear() {
ensureMutable();
clear();
}
/* (non-Javadoc)
* @see java.util.HashMap#put(java.lang.Object, java.lang.Object)
*/
@Override
public V put(K key, V value) {
ensureMutable();
return super.put(key, value);
}
/**
* Put.
*
* @param entry the entry
* @return the v
*/
public V put(Map.Entry entry) {
return put(entry.getKey(), entry.getValue());
}
/* (non-Javadoc)
* @see java.util.HashMap#putAll(java.util.Map)
*/
@Override
public void putAll(Map m) {
ensureMutable();
super.putAll(m);
}
/* (non-Javadoc)
* @see java.util.HashMap#remove(java.lang.Object)
*/
@Override
public V remove(Object key) {
ensureMutable();
return super.remove(key);
}
/**
* Equals.
*
* @param a the a
* @param b the b
* @return true, if successful
*/
private static boolean equals(Object a, Object b) {
if (a instanceof byte[] && b instanceof byte[]) {
return Arrays.equals((byte[]) a, (byte[]) b);
}
return a.equals(b);
}
/**
* Checks whether two {@link Map}s are equal. We don't use the default equals method of {@link Map} because it
* compares by identity not by content for byte arrays.
*
* @param the key type
* @param the value type
* @param a the a
* @param b the b
* @return true, if successful
*/
static boolean equals(Map a, Map b) {
if (a == b) {
return true;
}
if (a.size() != b.size()) {
return false;
}
for (Map.Entry entry : a.entrySet()) {
if (!b.containsKey(entry.getKey())) {
return false;
}
if (!equals(entry.getValue(), b.get(entry.getKey()))) {
return false;
}
}
return true;
}
/**
* Checks whether two map fields are equal.
*
* @param object the object
* @return true, if successful
*/
@SuppressWarnings("unchecked")
@Override
public boolean equals(Object object) {
return (object instanceof Map) && equals(this, (Map) object);
}
/**
* Calculate hash code for object.
*
* @param a the a
* @return the int
*/
private static int calculateHashCodeForObject(Object a) {
if (a instanceof byte[]) {
return Internal.hashCode((byte[]) a);
}
// Enums should be stored as integers internally.
if (a instanceof EnumLite) {
throw new UnsupportedOperationException();
}
return a.hashCode();
}
/**
* Calculates the hash code for a {@link Map}. We don't use the default hash code method of {@link Map} because for
* byte arrays and protobuf enums it use {@link Object#hashCode()}.
*
* @param the key type
* @param the value type
* @param a the a
* @return the int
*/
static int calculateHashCodeForMap(Map a) {
int result = 0;
for (Map.Entry entry : a.entrySet()) {
result += calculateHashCodeForObject(entry.getKey()) ^ calculateHashCodeForObject(entry.getValue());
}
return result;
}
/* (non-Javadoc)
* @see java.util.AbstractMap#hashCode()
*/
@Override
public int hashCode() {
return calculateHashCodeForMap(this);
}
/**
* Copy.
*
* @param object the object
* @return the object
*/
private static Object copy(Object object) {
if (object instanceof byte[]) {
byte[] data = (byte[]) object;
return Arrays.copyOf(data, data.length);
}
return object;
}
/**
* Makes a deep copy of a {@link Map}. Immutable objects in the map will be shared (e.g., integers, strings,
* immutable messages) and mutable ones will have a copy (e.g., byte arrays, mutable messages).
*
* @param the key type
* @param the value type
* @param map the map
* @return the map
*/
@SuppressWarnings("unchecked")
static Map copy(Map map) {
Map result = new LinkedHashMap();
for (Map.Entry entry : map.entrySet()) {
result.put(entry.getKey(), (V) copy(entry.getValue()));
}
return result;
}
/**
* Returns a deep copy of this map field.
*
* @return the map field lite
*/
public MapFieldLite mutableCopy() {
return isEmpty() ? new MapFieldLite() : new MapFieldLite(this);
}
/**
* Makes this field immutable. All subsequent modifications will throw an {@link UnsupportedOperationException}.
*/
public void makeImmutable() {
isMutable = false;
}
/**
* Checks if is mutable.
*
* @return true, if is mutable
*/
public boolean isMutable() {
return isMutable;
}
/**
* Ensure mutable.
*/
private void ensureMutable() {
if (!isMutable()) {
throw new UnsupportedOperationException();
}
}
}