com.xpn.xwiki.doc.merge.MergeUtils.java Source code

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Here is the source code for com.xpn.xwiki.doc.merge.MergeUtils.java

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/*
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package com.xpn.xwiki.doc.merge;

import java.io.StringReader;
import java.util.Collection;

import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;

import difflib.DiffUtils;
import difflib.Patch;

/**
 * Provide some 3 ways merging related methods.
 * 
 * @version $Id: 8275a983224a41ba197b5567f1a2cbe395e2ef09 $
 * @since 3.2M1
 */
public final class MergeUtils {
    /**
     * Utility class.
     */
    private MergeUtils() {

    }

    /**
     * Merge a String.
     * 
     * @param previousStr previous version of the string
     * @param newStr new version of the string
     * @param currentStr current version of the string
     * @param mergeResult the merge report
     * @return the merged string
     */
    // TODO: add support for line merge
    public static String mergeString(String previousStr, String newStr, String currentStr,
            MergeResult mergeResult) {
        String result = currentStr;

        try {
            Patch patch = DiffUtils.diff(IOUtils.readLines(new StringReader(previousStr)),
                    IOUtils.readLines(new StringReader(newStr)));
            if (patch.getDeltas().size() > 0) {
                result = StringUtils.join(patch.applyTo(IOUtils.readLines(new StringReader(currentStr))), '\n');

                mergeResult.setModified(true);
            }
        } catch (Exception e) {
            mergeResult.getErrors().add(e);
        }

        return result;
    }

    /**
     * Merge a {@link Collection}.
     * 
     * @param <T> the type of the lists elements
     * @param previousList previous version of the collection
     * @param newList new version of the collection
     * @param currentList current version of the collection to modify
     * @param mergeResult the merge report
     */
    public static <T> void mergeCollection(Collection<T> previousList, Collection<T> newList,
            Collection<T> currentList, MergeResult mergeResult) {
        for (T previousElement : previousList) {
            if (!newList.contains(previousElement)) {
                currentList.remove(previousElement);
            }
        }

        for (T newElement : newList) {
            if (!previousList.contains(newElement)) {
                currentList.add(newElement);
            }
        }
    }

    // TODO: add mergeList method which respect better the position of the elements than mergeCollection
}