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// Copyright 2014 The Bazel Authors. All rights reserved.
//
// 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.google.devtools.build.singlejar;
import com.google.devtools.build.singlejar.ZipEntryFilter.CustomMergeStrategy;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.annotation.concurrent.NotThreadSafe;
/**
* A strategy that merges a set of files by concatenating them. This is used
* for services files. By default, this class automatically adds a newline
* character {@code '\n'} between files if the previous file did not end with one.
*
* <p>Note: automatically inserting newline characters differs from the
* original behavior. Use {@link #ConcatenateStrategy(boolean)} to turn this
* behavior off.
*/
@NotThreadSafe
public final class ConcatenateStrategy implements CustomMergeStrategy {
// The strategy assumes that files are generally small. This is a first guess
// about the size of the files.
private static final int BUFFER_SIZE = 4096;
private final byte[] buffer = new byte[BUFFER_SIZE];
private byte lastByteCopied = '\n';
private final boolean appendNewLine;
ConcatenateStrategy() {
this(true);
}
/**
* @param appendNewLine Whether to add a newline character between files if
* the previous file did not end with one.
*/
ConcatenateStrategy(boolean appendNewLine) {
this.appendNewLine = appendNewLine;
}
@Override
public void merge(InputStream in, OutputStream out) throws IOException {
if (appendNewLine && lastByteCopied != '\n') {
out.write('\n');
lastByteCopied = '\n';
}
int bytesRead;
while ((bytesRead = in.read(buffer)) != -1) {
out.write(buffer, 0, bytesRead);
lastByteCopied = buffer[bytesRead - 1];
}
}
@Override
public void finish(OutputStream out) {
// No need to do anything. All the data was already written.
}
}
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