1 // Protocol Buffers - Google's data interchange format 2 // Copyright 2008 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; 32 33 import java.util.Collections; 34 import java.util.HashMap; 35 import java.util.Map; 36 37 /** 38 * Equivalent to {@link ExtensionRegistry} but supports only "lite" types. 39 * <p> 40 * If all of your types are lite types, then you only need to use 41 * {@code ExtensionRegistryLite}. Similarly, if all your types are regular 42 * types, then you only need {@link ExtensionRegistry}. Typically it does not 43 * make sense to mix the two, since if you have any regular types in your 44 * program, you then require the full runtime and lose all the benefits of 45 * the lite runtime, so you might as well make all your types be regular types. 46 * However, in some cases (e.g. when depending on multiple third-party libraries 47 * where one uses lite types and one uses regular), you may find yourself 48 * wanting to mix the two. In this case things get more complicated. 49 * <p> 50 * There are three factors to consider: Whether the type being extended is 51 * lite, whether the embedded type (in the case of a message-typed extension) 52 * is lite, and whether the extension itself is lite. Since all three are 53 * declared in different files, they could all be different. Here are all 54 * the combinations and which type of registry to use: 55 * <pre> 56 * Extended type Inner type Extension Use registry 57 * ======================================================================= 58 * lite lite lite ExtensionRegistryLite 59 * lite regular lite ExtensionRegistry 60 * regular regular regular ExtensionRegistry 61 * all other combinations not supported 62 * </pre> 63 * <p> 64 * Note that just as regular types are not allowed to contain lite-type fields, 65 * they are also not allowed to contain lite-type extensions. This is because 66 * regular types must be fully accessible via reflection, which in turn means 67 * that all the inner messages must also support reflection. On the other hand, 68 * since regular types implement the entire lite interface, there is no problem 69 * with embedding regular types inside lite types. 70 * 71 * @author kenton@google.com Kenton Varda 72 */ 73 public class ExtensionRegistryLite { 74 75 // Set true to enable lazy parsing feature for MessageSet. 76 // 77 // TODO(xiangl): Now we use a global flag to control whether enable lazy 78 // parsing feature for MessageSet, which may be too crude for some 79 // applications. Need to support this feature on smaller granularity. 80 private static volatile boolean eagerlyParseMessageSets = false; 81 isEagerlyParseMessageSets()82 public static boolean isEagerlyParseMessageSets() { 83 return eagerlyParseMessageSets; 84 } 85 setEagerlyParseMessageSets(boolean isEagerlyParse)86 public static void setEagerlyParseMessageSets(boolean isEagerlyParse) { 87 eagerlyParseMessageSets = isEagerlyParse; 88 } 89 90 /** Construct a new, empty instance. */ newInstance()91 public static ExtensionRegistryLite newInstance() { 92 return new ExtensionRegistryLite(); 93 } 94 95 /** Get the unmodifiable singleton empty instance. */ getEmptyRegistry()96 public static ExtensionRegistryLite getEmptyRegistry() { 97 return EMPTY; 98 } 99 100 /** Returns an unmodifiable view of the registry. */ getUnmodifiable()101 public ExtensionRegistryLite getUnmodifiable() { 102 return new ExtensionRegistryLite(this); 103 } 104 105 /** 106 * Find an extension by containing type and field number. 107 * 108 * @return Information about the extension if found, or {@code null} 109 * otherwise. 110 */ 111 @SuppressWarnings("unchecked") 112 public <ContainingType extends MessageLite> 113 GeneratedMessageLite.GeneratedExtension<ContainingType, ?> findLiteExtensionByNumber( final ContainingType containingTypeDefaultInstance, final int fieldNumber)114 findLiteExtensionByNumber( 115 final ContainingType containingTypeDefaultInstance, 116 final int fieldNumber) { 117 return (GeneratedMessageLite.GeneratedExtension<ContainingType, ?>) 118 extensionsByNumber.get( 119 new ObjectIntPair(containingTypeDefaultInstance, fieldNumber)); 120 } 121 122 /** Add an extension from a lite generated file to the registry. */ add( final GeneratedMessageLite.GeneratedExtension<?, ?> extension)123 public final void add( 124 final GeneratedMessageLite.GeneratedExtension<?, ?> extension) { 125 extensionsByNumber.put( 126 new ObjectIntPair(extension.getContainingTypeDefaultInstance(), 127 extension.getNumber()), 128 extension); 129 } 130 131 // ================================================================= 132 // Private stuff. 133 134 // Constructors are package-private so that ExtensionRegistry can subclass 135 // this. 136 ExtensionRegistryLite()137 ExtensionRegistryLite() { 138 this.extensionsByNumber = 139 new HashMap<ObjectIntPair, 140 GeneratedMessageLite.GeneratedExtension<?, ?>>(); 141 } 142 ExtensionRegistryLite(ExtensionRegistryLite other)143 ExtensionRegistryLite(ExtensionRegistryLite other) { 144 if (other == EMPTY) { 145 this.extensionsByNumber = Collections.emptyMap(); 146 } else { 147 this.extensionsByNumber = 148 Collections.unmodifiableMap(other.extensionsByNumber); 149 } 150 } 151 152 private final Map<ObjectIntPair, 153 GeneratedMessageLite.GeneratedExtension<?, ?>> 154 extensionsByNumber; 155 ExtensionRegistryLite(boolean empty)156 private ExtensionRegistryLite(boolean empty) { 157 this.extensionsByNumber = Collections.emptyMap(); 158 } 159 private static final ExtensionRegistryLite EMPTY = 160 new ExtensionRegistryLite(true); 161 162 /** A (Object, int) pair, used as a map key. */ 163 private static final class ObjectIntPair { 164 private final Object object; 165 private final int number; 166 ObjectIntPair(final Object object, final int number)167 ObjectIntPair(final Object object, final int number) { 168 this.object = object; 169 this.number = number; 170 } 171 172 @Override hashCode()173 public int hashCode() { 174 return System.identityHashCode(object) * ((1 << 16) - 1) + number; 175 } 176 @Override equals(final Object obj)177 public boolean equals(final Object obj) { 178 if (!(obj instanceof ObjectIntPair)) { 179 return false; 180 } 181 final ObjectIntPair other = (ObjectIntPair)obj; 182 return object == other.object && number == other.number; 183 } 184 } 185 } 186