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/*
 * Original Guava code is copyright (C) 2015 The Guava Authors.
 * Modifications from Guava are copyright (C) 2016 DiffPlug.
 *
 * 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 com.diffplug.common.io;

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

import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import com.diffplug.common.annotations.Beta;

/**
 * An OutputStream that counts the number of bytes written.
 *
 * @author Chris Nokleberg
 * @since 1.0
 */
@Beta
public final class CountingOutputStream extends FilterOutputStream {

	private long count;

	/**
	 * Wraps another output stream, counting the number of bytes written.
	 *
	 * @param out the output stream to be wrapped
	 */
	public CountingOutputStream(OutputStream out) {
		super(checkNotNull(out));
	}

	/** Returns the number of bytes written. */
	public long getCount() {
		return count;
	}

	@Override
	public void write(byte[] b, int off, int len) throws IOException {
		out.write(b, off, len);
		count += len;
	}

	@Override
	public void write(int b) throws IOException {
		out.write(b);
		count++;
	}

	// Overriding close() because FilterOutputStream's close() method pre-JDK8 has bad behavior:
	// it silently ignores any exception thrown by flush(). Instead, just close the delegate stream.
	// It should flush itself if necessary.
	@Override
	public void close() throws IOException {
		out.close();
	}
}