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Module containing support classes depending on Java SE 6, Guava 11 and Joda-Time 2.0

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/*
 * Copyright (C) the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.derquinse.common.io;

import static com.google.common.base.Preconditions.checkNotNull;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.nio.channels.WritableByteChannel;

import com.google.common.io.ByteSource;

/**
 * Byte source backed by a {@link ByteBuffer}.
 * @author Andres Rodriguez
 */
final class BufferByteSource extends ByteSource {
	/** Backing buffer. */
	private final ByteBuffer bytes;

	/**
	 * Constructor. The buffer parameters are not modified and its contents should not be modified.
	 * @param bytes Backing buffer.
	 */
	BufferByteSource(ByteBuffer bytes) {
		this.bytes = checkNotNull(bytes);
	}

	/** Returns a read-only view of the buffer. */
	ByteBuffer view() {
		return bytes.asReadOnlyBuffer();
	}

	@Override
	public InputStream openStream() throws IOException {
		return new ByteBufferInputStream(view());
	}

	@Override
	public long size() {
		return bytes.remaining();
	}

	@Override
	public byte[] read() {
		ByteBuffer b = view();
		byte[] data = new byte[b.remaining()];
		b.get(data);
		return data;
	}

	@Override
	public long copyTo(OutputStream output) throws IOException {
		final WritableByteChannel channel = Channels.newChannel(output);
		final ByteBuffer b = view();
		while (b.remaining() > 0) {
			channel.write(b);
		}
		return size();
	}
}