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// 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.facebook.presto.orc.protobuf;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
/**
* Equivalent to {@link ExtensionRegistry} but supports only "lite" types.
*
* If all of your types are lite types, then you only need to use
* {@code ExtensionRegistryLite}. Similarly, if all your types are regular
* types, then you only need {@link ExtensionRegistry}. Typically it does not
* make sense to mix the two, since if you have any regular types in your
* program, you then require the full runtime and lose all the benefits of
* the lite runtime, so you might as well make all your types be regular types.
* However, in some cases (e.g. when depending on multiple third-party libraries
* where one uses lite types and one uses regular), you may find yourself
* wanting to mix the two. In this case things get more complicated.
*
* There are three factors to consider: Whether the type being extended is
* lite, whether the embedded type (in the case of a message-typed extension)
* is lite, and whether the extension itself is lite. Since all three are
* declared in different files, they could all be different. Here are all
* the combinations and which type of registry to use:
*
* Extended type Inner type Extension Use registry
* =======================================================================
* lite lite lite ExtensionRegistryLite
* lite regular lite ExtensionRegistry
* regular regular regular ExtensionRegistry
* all other combinations not supported
*
*
* Note that just as regular types are not allowed to contain lite-type fields,
* they are also not allowed to contain lite-type extensions. This is because
* regular types must be fully accessible via reflection, which in turn means
* that all the inner messages must also support reflection. On the other hand,
* since regular types implement the entire lite interface, there is no problem
* with embedding regular types inside lite types.
*
* @author [email protected] Kenton Varda
*/
public class ExtensionRegistryLite {
// Set true to enable lazy parsing feature for MessageSet.
//
// TODO(xiangl): Now we use a global flag to control whether enable lazy
// parsing feature for MessageSet, which may be too crude for some
// applications. Need to support this feature on smaller granularity.
private static volatile boolean eagerlyParseMessageSets = false;
public static boolean isEagerlyParseMessageSets() {
return eagerlyParseMessageSets;
}
public static void setEagerlyParseMessageSets(boolean isEagerlyParse) {
eagerlyParseMessageSets = isEagerlyParse;
}
/** Construct a new, empty instance. */
public static ExtensionRegistryLite newInstance() {
return new ExtensionRegistryLite();
}
/** Get the unmodifiable singleton empty instance. */
public static ExtensionRegistryLite getEmptyRegistry() {
return EMPTY;
}
/** Returns an unmodifiable view of the registry. */
public ExtensionRegistryLite getUnmodifiable() {
return new ExtensionRegistryLite(this);
}
/**
* Find an extension by containing type and field number.
*
* @return Information about the extension if found, or {@code null}
* otherwise.
*/
@SuppressWarnings("unchecked")
public
GeneratedMessageLite.GeneratedExtension
findLiteExtensionByNumber(
final ContainingType containingTypeDefaultInstance,
final int fieldNumber) {
return (GeneratedMessageLite.GeneratedExtension)
extensionsByNumber.get(
new ObjectIntPair(containingTypeDefaultInstance, fieldNumber));
}
/** Add an extension from a lite generated file to the registry. */
public final void add(
final GeneratedMessageLite.GeneratedExtension extension) {
extensionsByNumber.put(
new ObjectIntPair(extension.getContainingTypeDefaultInstance(),
extension.getNumber()),
extension);
}
// =================================================================
// Private stuff.
// Constructors are package-private so that ExtensionRegistry can subclass
// this.
ExtensionRegistryLite() {
this.extensionsByNumber =
new HashMap>();
}
ExtensionRegistryLite(ExtensionRegistryLite other) {
if (other == EMPTY) {
this.extensionsByNumber = Collections.emptyMap();
} else {
this.extensionsByNumber =
Collections.unmodifiableMap(other.extensionsByNumber);
}
}
private final Map>
extensionsByNumber;
private ExtensionRegistryLite(boolean empty) {
this.extensionsByNumber = Collections.emptyMap();
}
private static final ExtensionRegistryLite EMPTY =
new ExtensionRegistryLite(true);
/** A (Object, int) pair, used as a map key. */
private static final class ObjectIntPair {
private final Object object;
private final int number;
ObjectIntPair(final Object object, final int number) {
this.object = object;
this.number = number;
}
@Override
public int hashCode() {
return System.identityHashCode(object) * ((1 << 16) - 1) + number;
}
@Override
public boolean equals(final Object obj) {
if (!(obj instanceof ObjectIntPair)) {
return false;
}
final ObjectIntPair other = (ObjectIntPair)obj;
return object == other.object && number == other.number;
}
}
}