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// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// http://code.google.com/p/protobuf/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
package com.google.protobuf;
import java.io.UnsupportedEncodingException;
/**
* The classes contained within are used internally by the Protocol Buffer
* library and generated message implementations. They are public only because
* those generated messages do not reside in the {@code protobuf} package.
* Others should not use this class directly.
*
* @author cyrusn@google.com (Cyrus Najmabadi)
*/
public class Internal {
/**
* Implementation of a Queue designed to have as little overhead as possible.
* No guarantees are made as to the order you will get values back from the
* queue. Currently it is a Last-In-First-Out implementation, but that may
* change in the future.
*
* Duplicate values are allowed, as are null values.
*
* Not threadsafe.
*
* @author cyrusn@google.com (Cyrus Najmabadi)
*/
public static final class QuickQueue<T> {
@SuppressWarnings("unchecked")
private T[] array = (T[]) new Object[16];
private int size;
/**
* Adds a value to the queue.
*
* @param value The value to add to the queue.
*/
public void offer(final T value) {
if (size == array.length) {
// I'd like to use Arrays.copy here. However, it is currently
// unavailable
// on android. So, for now, we just use the tried and true arraycopy
// technique.
@SuppressWarnings("unchecked")
final T[] copy = (T[]) new Object[size * 2];
System.arraycopy(array, 0, copy, 0, array.length);
array = copy;
}
array[size++] = value;
}
/**
* Removes some previously added value to the queue, or {@code null} if the
* queue is empty.
*
* @return An existing value in the queue, or {@code null} if the queue is
* empty.
*/
public T poll() {
if (size == 0) {
return null;
}
final T result = array[--size];
// make sure we null out the entry so that we're not keeping anything
// alive unnecessarily.
array[size] = null;
return result;
}
}
/**
* Instances of this class will provide a unique {@code QuickQueue} to each
* thread that accesses it. Very useful for providing free lists without
* needing to take any locks.
*
* @author cyrusn@google.com (Cyrus Najmabadi)
*/
public static final class ThreadLocalQuickQueue<T>
extends ThreadLocal<QuickQueue<T>> {
@Override
protected QuickQueue<T> initialValue() {
return new QuickQueue<T>();
}
}
/**
* Helper called by generated code to construct default values for string
* fields.
* <p>
* The protocol compiler does not actually contain a UTF-8 decoder -- it
* just pushes UTF-8-encoded text around without touching it. The one place
* where this presents a problem is when generating Java string literals.
* Unicode characters in the string literal would normally need to be encoded
* using a Unicode escape sequence, which would require decoding them.
* To get around this, protoc instead embeds the UTF-8 bytes into the
* generated code and leaves it to the runtime library to decode them.
* <p>
* It gets worse, though. If protoc just generated a byte array, like:
* new byte[] {0x12, 0x34, 0x56, 0x78}
* Java actually generates *code* which allocates an array and then fills
* in each value. This is much less efficient than just embedding the bytes
* directly into the bytecode. To get around this, we need another
* work-around. String literals are embedded directly, so protoc actually
* generates a string literal corresponding to the bytes. The easiest way
* to do this is to use the ISO-8859-1 character set, which corresponds to
* the first 256 characters of the Unicode range. Protoc can then use
* good old CEscape to generate the string.
* <p>
* So we have a string literal which represents a set of bytes which
* represents another string. This function -- stringDefaultValue --
* converts from the generated string to the string we actually want. The
* generated code calls this automatically.
*/
public static String stringDefaultValue(String bytes) {
try {
return new String(bytes.getBytes("ISO-8859-1"), "UTF-8");
} catch (UnsupportedEncodingException e) {
// This should never happen since all JVMs are required to implement
// both of the above character sets.
throw new IllegalStateException(
"Java VM does not support a standard character set.", e);
}
}
/**
* Helper called by generated code to construct default values for bytes
* fields.
* <p>
* This is a lot like {@link #stringDefaultValue}, but for bytes fields.
* In this case we only need the second of the two hacks -- allowing us to
* embed raw bytes as a string literal with ISO-8859-1 encoding.
*/
public static ByteString bytesDefaultValue(String bytes) {
try {
return ByteString.copyFrom(bytes.getBytes("ISO-8859-1"));
} catch (UnsupportedEncodingException e) {
// This should never happen since all JVMs are required to implement
// ISO-8859-1.
throw new IllegalStateException(
"Java VM does not support a standard character set.", e);
}
}
/**
* Interface for an enum value or value descriptor, to be used in FieldSet.
* The lite library stores enum values directly in FieldSets but the full
* library stores EnumValueDescriptors in order to better support reflection.
*/
public interface EnumLite {
int getNumber();
}
/**
* Interface for an object which maps integers to {@link EnumLite}s.
* {@link Descriptors.EnumDescriptor} implements this interface by mapping
* numbers to {@link Descriptors.EnumValueDescriptor}s. Additionally,
* every generated enum type has a static method internalGetValueMap() which
* returns an implementation of this type that maps numbers to enum values.
*/
public interface EnumLiteMap<T extends EnumLite> {
T findValueByNumber(int number);
}
}
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