// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// http://code.google.com/p/protobuf/
//
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package com.google.protobuf;
import com.google.protobuf.Descriptors.Descriptor;
import com.google.protobuf.Descriptors.FieldDescriptor;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
/**
* A table of known extensions, searchable by name or field number. When
* parsing a protocol message that might have extensions, you must provide
* an {@code ExtensionRegistry} in which you have registered any extensions
* that you want to be able to parse. Otherwise, those extensions will just
* be treated like unknown fields.
*
* <p>For example, if you had the {@code .proto} file:
*
* <pre>
* option java_class = "MyProto";
*
* message Foo {
* extensions 1000 to max;
* }
*
* extend Foo {
* optional int32 bar;
* }
* </pre>
*
* Then you might write code like:
*
* <pre>
* ExtensionRegistry registry = ExtensionRegistry.newInstance();
* registry.add(MyProto.bar);
* MyProto.Foo message = MyProto.Foo.parseFrom(input, registry);
* </pre>
*
* <p>Background:
*
* <p>You might wonder why this is necessary. Two alternatives might come to
* mind. First, you might imagine a system where generated extensions are
* automatically registered when their containing classes are loaded. This
* is a popular technique, but is bad design; among other things, it creates a
* situation where behavior can change depending on what classes happen to be
* loaded. It also introduces a security vulnerability, because an
* unprivileged class could cause its code to be called unexpectedly from a
* privileged class by registering itself as an extension of the right type.
*
* <p>Another option you might consider is lazy parsing: do not parse an
* extension until it is first requested, at which point the caller must
* provide a type to use. This introduces a different set of problems. First,
* it would require a mutex lock any time an extension was accessed, which
* would be slow. Second, corrupt data would not be detected until first
* access, at which point it would be much harder to deal with it. Third, it
* could violate the expectation that message objects are immutable, since the
* type provided could be any arbitrary message class. An unprivileged user
* could take advantage of this to inject a mutable object into a message
* belonging to privileged code and create mischief.
*
* @author kenton@google.com Kenton Varda
*/
public class ExtensionRegistry extends ExtensionRegistryLite {
/** Construct a new, empty instance. */
public static ExtensionRegistry newInstance() {
return new ExtensionRegistry();
}
/** Get the unmodifiable singleton empty instance. */
public static ExtensionRegistry getEmptyRegistry() {
return EMPTY;
}
/** Returns an unmodifiable view of the registry. */
@Override
public ExtensionRegistry getUnmodifiable() {
return new ExtensionRegistry(this);
}
/** A (Descriptor, Message) pair, returned by lookup methods. */
public static final class ExtensionInfo {
/** The extension's descriptor. */
public final FieldDescriptor descriptor;
/**
* A default instance of the extension's type, if it has a message type.
* Otherwise, {@code null}.
*/
public final Message defaultInstance;
private ExtensionInfo(final FieldDescriptor descriptor) {
this.descriptor = descriptor;
defaultInstance = null;
}
private ExtensionInfo(final FieldDescriptor descriptor,
final Message defaultInstance) {
this.descriptor = descriptor;
this.defaultInstance = defaultInstance;
}
}
/**
* Deprecated. Use {@link #findImmutableExtensionByName(String)} instead.
*/
public ExtensionInfo findExtensionByName(final String fullName) {
return findImmutableExtensionByName(fullName);
}
/**
* Find an extension for immutable APIs by fully-qualified field name,
* in the proto namespace. i.e. {@code result.descriptor.fullName()} will
* match {@code fullName} if a match is found.
*
* @return Information about the extension if found, or {@code null}
* otherwise.
*/
public ExtensionInfo findImmutableExtensionByName(final String fullName) {
return immutableExtensionsByName.get(fullName);
}
/**
* Find an extension for mutable APIs by fully-qualified field name,
* in the proto namespace. i.e. {@code result.descriptor.fullName()} will
* match {@code fullName} if a match is found.
*
* @return Information about the extension if found, or {@code null}
* otherwise.
*/
public ExtensionInfo findMutableExtensionByName(final String fullName) {
return mutableExtensionsByName.get(fullName);
}
/**
* Deprecated. Use {@link #findImmutableExtensionByNumber(
* Descriptors.Descriptor, int)}
*/
public ExtensionInfo findExtensionByNumber(
final Descriptor containingType, final int fieldNumber) {
return findImmutableExtensionByNumber(containingType, fieldNumber);
}
/**
* Find an extension by containing type and field number for immutable APIs.
*
* @return Information about the extension if found, or {@code null}
* otherwise.
*/
public ExtensionInfo findImmutableExtensionByNumber(
final Descriptor containingType, final int fieldNumber) {
return immutableExtensionsByNumber.get(
new DescriptorIntPair(containingType, fieldNumber));
}
/**
* Find an extension by containing type and field number for mutable APIs.
*
* @return Information about the extension if found, or {@code null}
* otherwise.
*/
public ExtensionInfo findMutableExtensionByNumber(
final Descriptor containingType, final int fieldNumber) {
return mutableExtensionsByNumber.get(
new DescriptorIntPair(containingType, fieldNumber));
}
/**
* Find all extensions for mutable APIs by fully-qualified name of
* extended class. Note that this method is more computationally expensive
* than getting a single extension by name or number.
*
* @return Information about the extensions found, or {@code null} if there
* are none.
*/
public Set<ExtensionInfo> getAllMutableExtensionsByExtendedType(final String fullName) {
HashSet<ExtensionInfo> extensions = new HashSet<ExtensionInfo>();
for (DescriptorIntPair pair : mutableExtensionsByNumber.keySet()) {
if (pair.descriptor.getFullName().equals(fullName)) {
extensions.add(mutableExtensionsByNumber.get(pair));
}
}
return extensions;
}
/**
* Find all extensions for immutable APIs by fully-qualified name of
* extended class. Note that this method is more computationally expensive
* than getting a single extension by name or number.
*
* @return Information about the extensions found, or {@code null} if there
* are none.
*/
public Set<ExtensionInfo> getAllImmutableExtensionsByExtendedType(final String fullName) {
HashSet<ExtensionInfo> extensions = new HashSet<ExtensionInfo>();
for (DescriptorIntPair pair : immutableExtensionsByNumber.keySet()) {
if (pair.descriptor.getFullName().equals(fullName)) {
extensions.add(immutableExtensionsByNumber.get(pair));
}
}
return extensions;
}
/** Add an extension from a generated file to the registry. */
public void add(final Extension<?, ?> extension) {
if (extension.getExtensionType() != Extension.ExtensionType.IMMUTABLE &&
extension.getExtensionType() != Extension.ExtensionType.MUTABLE) {
// do not support other extension types. ignore
return;
}
add(newExtensionInfo(extension), extension.getExtensionType());
}
static ExtensionInfo newExtensionInfo(final Extension<?, ?> extension) {
if (extension.getDescriptor().getJavaType() ==
FieldDescriptor.JavaType.MESSAGE) {
if (extension.getMessageDefaultInstance() == null) {
throw new IllegalStateException(
"Registered message-type extension had null default instance: " +
extension.getDescriptor().getFullName());
}
return new ExtensionInfo(extension.getDescriptor(),
(Message) extension.getMessageDefaultInstance());
} else {
return new ExtensionInfo(extension.getDescriptor(), null);
}
}
/** Add a non-message-type extension to the registry by descriptor. */
public void add(final FieldDescriptor type) {
if (type.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
throw new IllegalArgumentException(
"ExtensionRegistry.add() must be provided a default instance when " +
"adding an embedded message extension.");
}
ExtensionInfo info = new ExtensionInfo(type, null);
add(info, Extension.ExtensionType.IMMUTABLE);
add(info, Extension.ExtensionType.MUTABLE);
}
/** Add a message-type extension to the registry by descriptor. */
public void add(final FieldDescriptor type, final Message defaultInstance) {
if (type.getJavaType() != FieldDescriptor.JavaType.MESSAGE) {
throw new IllegalArgumentException(
"ExtensionRegistry.add() provided a default instance for a " +
"non-message extension.");
}
add(new ExtensionInfo(type, defaultInstance),
Extension.ExtensionType.IMMUTABLE);
}
// =================================================================
// Private stuff.
private ExtensionRegistry() {
this.immutableExtensionsByName = new HashMap<String, ExtensionInfo>();
this.mutableExtensionsByName = new HashMap<String, ExtensionInfo>();
this.immutableExtensionsByNumber =
new HashMap<DescriptorIntPair, ExtensionInfo>();
this.mutableExtensionsByNumber =
new HashMap<DescriptorIntPair, ExtensionInfo>();
}
private ExtensionRegistry(ExtensionRegistry other) {
super(other);
this.immutableExtensionsByName =
Collections.unmodifiableMap(other.immutableExtensionsByName);
this.mutableExtensionsByName =
Collections.unmodifiableMap(other.mutableExtensionsByName);
this.immutableExtensionsByNumber =
Collections.unmodifiableMap(other.immutableExtensionsByNumber);
this.mutableExtensionsByNumber =
Collections.unmodifiableMap(other.mutableExtensionsByNumber);
}
private final Map<String, ExtensionInfo> immutableExtensionsByName;
private final Map<String, ExtensionInfo> mutableExtensionsByName;
private final Map<DescriptorIntPair, ExtensionInfo> immutableExtensionsByNumber;
private final Map<DescriptorIntPair, ExtensionInfo> mutableExtensionsByNumber;
ExtensionRegistry(boolean empty) {
super(ExtensionRegistryLite.getEmptyRegistry());
this.immutableExtensionsByName =
Collections.<String, ExtensionInfo>emptyMap();
this.mutableExtensionsByName =
Collections.<String, ExtensionInfo>emptyMap();
this.immutableExtensionsByNumber =
Collections.<DescriptorIntPair, ExtensionInfo>emptyMap();
this.mutableExtensionsByNumber =
Collections.<DescriptorIntPair, ExtensionInfo>emptyMap();
}
private static final ExtensionRegistry EMPTY = new ExtensionRegistry(true);
private void add(
final ExtensionInfo extension,
final Extension.ExtensionType extensionType) {
if (!extension.descriptor.isExtension()) {
throw new IllegalArgumentException(
"ExtensionRegistry.add() was given a FieldDescriptor for a regular " +
"(non-extension) field.");
}
Map<String, ExtensionInfo> extensionsByName;
Map<DescriptorIntPair, ExtensionInfo> extensionsByNumber;
switch (extensionType) {
case IMMUTABLE:
extensionsByName = immutableExtensionsByName;
extensionsByNumber = immutableExtensionsByNumber;
break;
case MUTABLE:
extensionsByName = mutableExtensionsByName;
extensionsByNumber = mutableExtensionsByNumber;
break;
default:
// Ignore the unknown supported type.
return;
}
extensionsByName.put(extension.descriptor.getFullName(), extension);
extensionsByNumber.put(
new DescriptorIntPair(extension.descriptor.getContainingType(),
extension.descriptor.getNumber()),
extension);
final FieldDescriptor field = extension.descriptor;
if (field.getContainingType().getOptions().getMessageSetWireFormat() &&
field.getType() == FieldDescriptor.Type.MESSAGE &&
field.isOptional() &&
field.getExtensionScope() == field.getMessageType()) {
// This is an extension of a MessageSet type defined within the extension
// type's own scope. For backwards-compatibility, allow it to be looked
// up by type name.
extensionsByName.put(field.getMessageType().getFullName(), extension);
}
}
/** A (GenericDescriptor, int) pair, used as a map key. */
private static final class DescriptorIntPair {
private final Descriptor descriptor;
private final int number;
DescriptorIntPair(final Descriptor descriptor, final int number) {
this.descriptor = descriptor;
this.number = number;
}
@Override
public int hashCode() {
return descriptor.hashCode() * ((1 << 16) - 1) + number;
}
@Override
public boolean equals(final Object obj) {
if (!(obj instanceof DescriptorIntPair)) {
return false;
}
final DescriptorIntPair other = (DescriptorIntPair)obj;
return descriptor == other.descriptor && number == other.number;
}
}
}