org.eclipse.jgit.merge.ThreeWayMerger.java Source code

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Here is the source code for org.eclipse.jgit.merge.ThreeWayMerger.java

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/*
 * Copyright (C) 2009, Google Inc.
 * Copyright (C) 2012, Research In Motion Limited
 * and other copyright owners as documented in the project's IP log.
 *
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
 * accompanies this distribution, is reproduced below, and is
 * available at http://www.eclipse.org/org/documents/edl-v10.php
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 * - Neither the name of the Eclipse Foundation, Inc. nor the
 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.eclipse.jgit.merge;

import java.io.IOException;

import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectInserter;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevTree;
import org.eclipse.jgit.treewalk.AbstractTreeIterator;
import org.eclipse.jgit.treewalk.EmptyTreeIterator;

/**
 * A merge of 2 trees, using a common base ancestor tree.
 */
public abstract class ThreeWayMerger extends Merger {
    private RevTree baseTree;

    private ObjectId baseCommitId;

    /**
     * Create a new merge instance for a repository.
     *
     * @param local
     *            the repository this merger will read and write data on.
     */
    protected ThreeWayMerger(Repository local) {
        super(local);
    }

    /**
     * Create a new merge instance for a repository.
     *
     * @param local
     *            the repository this merger will read and write data on.
     * @param inCore
     *            perform the merge in core with no working folder involved
     */
    protected ThreeWayMerger(Repository local, boolean inCore) {
        this(local);
    }

    /**
     * Create a new in-core merge instance from an inserter.
     *
     * @param inserter
     *            the inserter to write objects to.
     * @since 4.8
     */
    protected ThreeWayMerger(ObjectInserter inserter) {
        super(inserter);
    }

    /**
     * Set the common ancestor tree.
     *
     * @param id
     *            common base treeish; null to automatically compute the common
     *            base from the input commits during
     *            {@link #merge(AnyObjectId...)}.
     * @throws org.eclipse.jgit.errors.IncorrectObjectTypeException
     *             the object is not a treeish.
     * @throws org.eclipse.jgit.errors.MissingObjectException
     *             the object does not exist.
     * @throws java.io.IOException
     *             the object could not be read.
     */
    public void setBase(AnyObjectId id) throws MissingObjectException, IncorrectObjectTypeException, IOException {
        if (id != null) {
            baseTree = walk.parseTree(id);
        } else {
            baseTree = null;
        }
    }

    /** {@inheritDoc} */
    @Override
    public boolean merge(AnyObjectId... tips) throws IOException {
        if (tips.length != 2)
            return false;
        return super.merge(tips);
    }

    /** {@inheritDoc} */
    @Override
    public ObjectId getBaseCommitId() {
        return baseCommitId;
    }

    /**
     * Create an iterator to walk the merge base.
     *
     * @return an iterator over the caller-specified merge base, or the natural
     *         merge base of the two input commits.
     * @throws java.io.IOException
     */
    protected AbstractTreeIterator mergeBase() throws IOException {
        if (baseTree != null) {
            return openTree(baseTree);
        }
        RevCommit baseCommit = (baseCommitId != null) ? walk.parseCommit(baseCommitId)
                : getBaseCommit(sourceCommits[0], sourceCommits[1]);
        if (baseCommit == null) {
            baseCommitId = null;
            return new EmptyTreeIterator();
        }
        baseCommitId = baseCommit.toObjectId();
        return openTree(baseCommit.getTree());
    }
}