package org.apache.torque.generator.merge;
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import org.apache.torque.generator.GeneratorException;
import org.eclipse.jgit.diff.RawText;
import org.eclipse.jgit.diff.RawTextComparator;
import org.eclipse.jgit.merge.MergeAlgorithm;
import org.eclipse.jgit.merge.MergeFormatter;
import org.eclipse.jgit.merge.MergeResult;
/**
* Can execute a three-way merge. This class is thread safe.
*
* @version $Id: ThreeWayMerger.java 1331190 2012-04-27 02:41:35Z tfischer $
*/
public class ThreeWayMerger
{
/**
* Performs a three-way merge.
*
* @param base the base from which the other two versions are derived,
* not null.
* @param generated the newly generated text, not null.
* @param edited the possibly edited text, not null.
* @param charsetName the name of the character set, not null.
* @return the merge result, not null.
*
* @throws GeneratorException if merging fails.
*/
public String merge(
String base,
String generated,
String edited,
String charsetName)
throws GeneratorException
{
MergeAlgorithm mergeAlgorithm = new MergeAlgorithm();
MergeResult<RawText> mergeResult;
try
{
mergeResult = mergeAlgorithm.merge(
RawTextComparator.DEFAULT,
new RawText(base.getBytes(charsetName)),
new RawText(generated.getBytes(charsetName)),
new RawText(edited.getBytes(charsetName)));
}
catch (UnsupportedEncodingException e)
{
throw new GeneratorException(
"unknown character set " + charsetName,
e);
}
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
try
{
new MergeFormatter().formatMerge(
outputStream,
mergeResult,
"base",
"generated",
"edited",
charsetName);
}
catch (IOException e)
{
throw new GeneratorException("could nor render merge result", e);
}
try
{
String result
= new String(outputStream.toByteArray(), charsetName);
return result;
}
catch (UnsupportedEncodingException e)
{
throw new GeneratorException(
"unknown character set " + charsetName,
e);
}
}
}