1 // Protocol Buffers - Google's data interchange format 2 // Copyright 2013 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.nano; 32 33 import java.util.HashMap; 34 import java.util.Map; 35 36 /** 37 * Utility class for maps support. 38 */ 39 public final class MapFactories { 40 public static interface MapFactory { 41 <K, V> Map<K, V> forMap(Map<K, V> oldMap); 42 } 43 44 // NOTE(liujisi): The factory setter is temporarily marked as package private. 45 // The way to provide customized implementations of maps for different 46 // platforms are still under discussion. Mark it as private to avoid exposing 47 // the API in proto3 alpha release. 48 /* public */ static void setMapFactory(MapFactory newMapFactory) { 49 mapFactory = newMapFactory; 50 } 51 52 public static MapFactory getMapFactory() { 53 return mapFactory; 54 } 55 56 private static class DefaultMapFactory implements MapFactory { 57 public <K, V> Map<K, V> forMap(Map<K, V> oldMap) { 58 if (oldMap == null) { 59 return new HashMap<K, V>(); 60 } 61 return oldMap; 62 } 63 } 64 private static volatile MapFactory mapFactory = new DefaultMapFactory(); 65 66 private MapFactories() {} 67 } 68
