PageRenderTime 29ms CodeModel.GetById 18ms app.highlight 8ms RepoModel.GetById 1ms app.codeStats 0ms

/thirdparty/breakpad/third_party/protobuf/protobuf/java/src/main/java/com/google/protobuf/ExtensionRegistry.java

http://github.com/tomahawk-player/tomahawk
Java | 266 lines | 127 code | 25 blank | 114 comment | 16 complexity | 9694c4b7a8769c82190145277c5cd258 MD5 | raw file
  1// Protocol Buffers - Google's data interchange format
  2// Copyright 2008 Google Inc.  All rights reserved.
  3// http://code.google.com/p/protobuf/
  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
 31package com.google.protobuf;
 32
 33import com.google.protobuf.Descriptors.Descriptor;
 34import com.google.protobuf.Descriptors.FieldDescriptor;
 35
 36import java.util.Collections;
 37import java.util.HashMap;
 38import java.util.Map;
 39
 40/**
 41 * A table of known extensions, searchable by name or field number.  When
 42 * parsing a protocol message that might have extensions, you must provide
 43 * an {@code ExtensionRegistry} in which you have registered any extensions
 44 * that you want to be able to parse.  Otherwise, those extensions will just
 45 * be treated like unknown fields.
 46 *
 47 * <p>For example, if you had the {@code .proto} file:
 48 *
 49 * <pre>
 50 * option java_class = "MyProto";
 51 *
 52 * message Foo {
 53 *   extensions 1000 to max;
 54 * }
 55 *
 56 * extend Foo {
 57 *   optional int32 bar;
 58 * }
 59 * </pre>
 60 *
 61 * Then you might write code like:
 62 *
 63 * <pre>
 64 * ExtensionRegistry registry = ExtensionRegistry.newInstance();
 65 * registry.add(MyProto.bar);
 66 * MyProto.Foo message = MyProto.Foo.parseFrom(input, registry);
 67 * </pre>
 68 *
 69 * <p>Background:
 70 *
 71 * <p>You might wonder why this is necessary.  Two alternatives might come to
 72 * mind.  First, you might imagine a system where generated extensions are
 73 * automatically registered when their containing classes are loaded.  This
 74 * is a popular technique, but is bad design; among other things, it creates a
 75 * situation where behavior can change depending on what classes happen to be
 76 * loaded.  It also introduces a security vulnerability, because an
 77 * unprivileged class could cause its code to be called unexpectedly from a
 78 * privileged class by registering itself as an extension of the right type.
 79 *
 80 * <p>Another option you might consider is lazy parsing: do not parse an
 81 * extension until it is first requested, at which point the caller must
 82 * provide a type to use.  This introduces a different set of problems.  First,
 83 * it would require a mutex lock any time an extension was accessed, which
 84 * would be slow.  Second, corrupt data would not be detected until first
 85 * access, at which point it would be much harder to deal with it.  Third, it
 86 * could violate the expectation that message objects are immutable, since the
 87 * type provided could be any arbitrary message class.  An unprivileged user
 88 * could take advantage of this to inject a mutable object into a message
 89 * belonging to privileged code and create mischief.
 90 *
 91 * @author kenton@google.com Kenton Varda
 92 */
 93public final class ExtensionRegistry extends ExtensionRegistryLite {
 94  /** Construct a new, empty instance. */
 95  public static ExtensionRegistry newInstance() {
 96    return new ExtensionRegistry();
 97  }
 98
 99  /** Get the unmodifiable singleton empty instance. */
100  public static ExtensionRegistry getEmptyRegistry() {
101    return EMPTY;
102  }
103
104  /** Returns an unmodifiable view of the registry. */
105  @Override
106  public ExtensionRegistry getUnmodifiable() {
107    return new ExtensionRegistry(this);
108  }
109
110  /** A (Descriptor, Message) pair, returned by lookup methods. */
111  public static final class ExtensionInfo {
112    /** The extension's descriptor. */
113    public final FieldDescriptor descriptor;
114
115    /**
116     * A default instance of the extension's type, if it has a message type.
117     * Otherwise, {@code null}.
118     */
119    public final Message defaultInstance;
120
121    private ExtensionInfo(final FieldDescriptor descriptor) {
122      this.descriptor = descriptor;
123      defaultInstance = null;
124    }
125    private ExtensionInfo(final FieldDescriptor descriptor,
126                          final Message defaultInstance) {
127      this.descriptor = descriptor;
128      this.defaultInstance = defaultInstance;
129    }
130  }
131
132  /**
133   * Find an extension by fully-qualified field name, in the proto namespace.
134   * I.e. {@code result.descriptor.fullName()} will match {@code fullName} if
135   * a match is found.
136   *
137   * @return Information about the extension if found, or {@code null}
138   *         otherwise.
139   */
140  public ExtensionInfo findExtensionByName(final String fullName) {
141    return extensionsByName.get(fullName);
142  }
143
144  /**
145   * Find an extension by containing type and field number.
146   *
147   * @return Information about the extension if found, or {@code null}
148   *         otherwise.
149   */
150  public ExtensionInfo findExtensionByNumber(final Descriptor containingType,
151                                             final int fieldNumber) {
152    return extensionsByNumber.get(
153      new DescriptorIntPair(containingType, fieldNumber));
154  }
155
156  /** Add an extension from a generated file to the registry. */
157  public void add(final GeneratedMessage.GeneratedExtension<?, ?> extension) {
158    if (extension.getDescriptor().getJavaType() ==
159        FieldDescriptor.JavaType.MESSAGE) {
160      if (extension.getMessageDefaultInstance() == null) {
161        throw new IllegalStateException(
162            "Registered message-type extension had null default instance: " +
163            extension.getDescriptor().getFullName());
164      }
165      add(new ExtensionInfo(extension.getDescriptor(),
166                            extension.getMessageDefaultInstance()));
167    } else {
168      add(new ExtensionInfo(extension.getDescriptor(), null));
169    }
170  }
171
172  /** Add a non-message-type extension to the registry by descriptor. */
173  public void add(final FieldDescriptor type) {
174    if (type.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
175      throw new IllegalArgumentException(
176        "ExtensionRegistry.add() must be provided a default instance when " +
177        "adding an embedded message extension.");
178    }
179    add(new ExtensionInfo(type, null));
180  }
181
182  /** Add a message-type extension to the registry by descriptor. */
183  public void add(final FieldDescriptor type, final Message defaultInstance) {
184    if (type.getJavaType() != FieldDescriptor.JavaType.MESSAGE) {
185      throw new IllegalArgumentException(
186        "ExtensionRegistry.add() provided a default instance for a " +
187        "non-message extension.");
188    }
189    add(new ExtensionInfo(type, defaultInstance));
190  }
191
192  // =================================================================
193  // Private stuff.
194
195  private ExtensionRegistry() {
196    this.extensionsByName = new HashMap<String, ExtensionInfo>();
197    this.extensionsByNumber = new HashMap<DescriptorIntPair, ExtensionInfo>();
198  }
199
200  private ExtensionRegistry(ExtensionRegistry other) {
201    super(other);
202    this.extensionsByName = Collections.unmodifiableMap(other.extensionsByName);
203    this.extensionsByNumber =
204        Collections.unmodifiableMap(other.extensionsByNumber);
205  }
206
207  private final Map<String, ExtensionInfo> extensionsByName;
208  private final Map<DescriptorIntPair, ExtensionInfo> extensionsByNumber;
209
210  private ExtensionRegistry(boolean empty) {
211    super(ExtensionRegistryLite.getEmptyRegistry());
212    this.extensionsByName = Collections.<String, ExtensionInfo>emptyMap();
213    this.extensionsByNumber =
214        Collections.<DescriptorIntPair, ExtensionInfo>emptyMap();
215  }
216  private static final ExtensionRegistry EMPTY = new ExtensionRegistry(true);
217
218  private void add(final ExtensionInfo extension) {
219    if (!extension.descriptor.isExtension()) {
220      throw new IllegalArgumentException(
221        "ExtensionRegistry.add() was given a FieldDescriptor for a regular " +
222        "(non-extension) field.");
223    }
224
225    extensionsByName.put(extension.descriptor.getFullName(), extension);
226    extensionsByNumber.put(
227      new DescriptorIntPair(extension.descriptor.getContainingType(),
228                            extension.descriptor.getNumber()),
229      extension);
230
231    final FieldDescriptor field = extension.descriptor;
232    if (field.getContainingType().getOptions().getMessageSetWireFormat() &&
233        field.getType() == FieldDescriptor.Type.MESSAGE &&
234        field.isOptional() &&
235        field.getExtensionScope() == field.getMessageType()) {
236      // This is an extension of a MessageSet type defined within the extension
237      // type's own scope.  For backwards-compatibility, allow it to be looked
238      // up by type name.
239      extensionsByName.put(field.getMessageType().getFullName(), extension);
240    }
241  }
242
243  /** A (GenericDescriptor, int) pair, used as a map key. */
244  private static final class DescriptorIntPair {
245    private final Descriptor descriptor;
246    private final int number;
247
248    DescriptorIntPair(final Descriptor descriptor, final int number) {
249      this.descriptor = descriptor;
250      this.number = number;
251    }
252
253    @Override
254    public int hashCode() {
255      return descriptor.hashCode() * ((1 << 16) - 1) + number;
256    }
257    @Override
258    public boolean equals(final Object obj) {
259      if (!(obj instanceof DescriptorIntPair)) {
260        return false;
261      }
262      final DescriptorIntPair other = (DescriptorIntPair)obj;
263      return descriptor == other.descriptor && number == other.number;
264    }
265  }
266}