Initial JGit contribution to eclipse.org

Per CQ 3448 this is the initial contribution of the JGit project
to eclipse.org.  It is derived from the historical JGit repository
at commit 3a2dd9921c8a08740a9e02c421469e5b1a9e47cb.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

1 files changed, 235 insertions, 0 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/merge/Merger.java b/org.eclipse.jgit/src/org/eclipse/jgit/merge/Merger.java
new file mode 100644
index 0000000000..275a6d68ff
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/merge/Merger.java
@@ -0,0 +1,235 @@
+/*
+ * Copyright (C) 2008-2009, Google Inc.
+ * 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.lib.AnyObjectId;
+import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.ObjectWriter;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.lib.WindowCursor;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevObject;
+import org.eclipse.jgit.revwalk.RevTree;
+import org.eclipse.jgit.revwalk.RevWalk;
+import org.eclipse.jgit.revwalk.filter.RevFilter;
+import org.eclipse.jgit.treewalk.AbstractTreeIterator;
+import org.eclipse.jgit.treewalk.CanonicalTreeParser;
+import org.eclipse.jgit.treewalk.EmptyTreeIterator;
+
+/**
+ * Instance of a specific {@link MergeStrategy} for a single {@link Repository}.
+ */
+public abstract class Merger {
+	/** The repository this merger operates on. */
+	protected final Repository db;
+
+	/** A RevWalk for computing merge bases, or listing incoming commits. */
+	protected final RevWalk walk;
+
+	private ObjectWriter writer;
+
+	/** The original objects supplied in the merge; this can be any tree-ish. */
+	protected RevObject[] sourceObjects;
+
+	/** If {@link #sourceObjects}[i] is a commit, this is the commit. */
+	protected RevCommit[] sourceCommits;
+
+	/** The trees matching every entry in {@link #sourceObjects}. */
+	protected RevTree[] sourceTrees;
+
+	/**
+	 * Create a new merge instance for a repository.
+	 *
+	 * @param local
+	 *            the repository this merger will read and write data on.
+	 */
+	protected Merger(final Repository local) {
+		db = local;
+		walk = new RevWalk(db);
+	}
+
+	/**
+	 * @return the repository this merger operates on.
+	 */
+	public Repository getRepository() {
+		return db;
+	}
+
+	/**
+	 * @return an object writer to create objects in {@link #getRepository()}.
+	 */
+	public ObjectWriter getObjectWriter() {
+		if (writer == null)
+			writer = new ObjectWriter(getRepository());
+		return writer;
+	}
+
+	/**
+	 * Merge together two or more tree-ish objects.
+	 * <p>
+	 * Any tree-ish may be supplied as inputs. Commits and/or tags pointing at
+	 * trees or commits may be passed as input objects.
+	 *
+	 * @param tips
+	 *            source trees to be combined together. The merge base is not
+	 *            included in this set.
+	 * @return true if the merge was completed without conflicts; false if the
+	 *         merge strategy cannot handle this merge or there were conflicts
+	 *         preventing it from automatically resolving all paths.
+	 * @throws IncorrectObjectTypeException
+	 *             one of the input objects is not a commit, but the strategy
+	 *             requires it to be a commit.
+	 * @throws IOException
+	 *             one or more sources could not be read, or outputs could not
+	 *             be written to the Repository.
+	 */
+	public boolean merge(final AnyObjectId[] tips) throws IOException {
+		sourceObjects = new RevObject[tips.length];
+		for (int i = 0; i < tips.length; i++)
+			sourceObjects[i] = walk.parseAny(tips[i]);
+
+		sourceCommits = new RevCommit[sourceObjects.length];
+		for (int i = 0; i < sourceObjects.length; i++) {
+			try {
+				sourceCommits[i] = walk.parseCommit(sourceObjects[i]);
+			} catch (IncorrectObjectTypeException err) {
+				sourceCommits[i] = null;
+			}
+		}
+
+		sourceTrees = new RevTree[sourceObjects.length];
+		for (int i = 0; i < sourceObjects.length; i++)
+			sourceTrees[i] = walk.parseTree(sourceObjects[i]);
+
+		return mergeImpl();
+	}
+
+	/**
+	 * Create an iterator to walk the merge base of two commits.
+	 *
+	 * @param aIdx
+	 *            index of the first commit in {@link #sourceObjects}.
+	 * @param bIdx
+	 *            index of the second commit in {@link #sourceObjects}.
+	 * @return the new iterator
+	 * @throws IncorrectObjectTypeException
+	 *             one of the input objects is not a commit.
+	 * @throws IOException
+	 *             objects are missing or multiple merge bases were found.
+	 */
+	protected AbstractTreeIterator mergeBase(final int aIdx, final int bIdx)
+			throws IOException {
+		if (sourceCommits[aIdx] == null)
+			throw new IncorrectObjectTypeException(sourceObjects[aIdx],
+					Constants.TYPE_COMMIT);
+		if (sourceCommits[bIdx] == null)
+			throw new IncorrectObjectTypeException(sourceObjects[bIdx],
+					Constants.TYPE_COMMIT);
+
+		walk.reset();
+		walk.setRevFilter(RevFilter.MERGE_BASE);
+		walk.markStart(sourceCommits[aIdx]);
+		walk.markStart(sourceCommits[bIdx]);
+		final RevCommit base = walk.next();
+		if (base == null)
+			return new EmptyTreeIterator();
+		final RevCommit base2 = walk.next();
+		if (base2 != null) {
+			throw new IOException("Multiple merge bases for:" + "\n  "
+					+ sourceCommits[aIdx].name() + "\n  "
+					+ sourceCommits[bIdx].name() + "found:" + "\n  "
+					+ base.name() + "\n  " + base2.name());
+		}
+		return openTree(base.getTree());
+	}
+
+	/**
+	 * Open an iterator over a tree.
+	 *
+	 * @param treeId
+	 *            the tree to scan; must be a tree (not a treeish).
+	 * @return an iterator for the tree.
+	 * @throws IncorrectObjectTypeException
+	 *             the input object is not a tree.
+	 * @throws IOException
+	 *             the tree object is not found or cannot be read.
+	 */
+	protected AbstractTreeIterator openTree(final AnyObjectId treeId)
+			throws IncorrectObjectTypeException, IOException {
+		final WindowCursor curs = new WindowCursor();
+		try {
+			return new CanonicalTreeParser(null, db, treeId, curs);
+		} finally {
+			curs.release();
+		}
+	}
+
+	/**
+	 * Execute the merge.
+	 * <p>
+	 * This method is called from {@link #merge(AnyObjectId[])} after the
+	 * {@link #sourceObjects}, {@link #sourceCommits} and {@link #sourceTrees}
+	 * have been populated.
+	 *
+	 * @return true if the merge was completed without conflicts; false if the
+	 *         merge strategy cannot handle this merge or there were conflicts
+	 *         preventing it from automatically resolving all paths.
+	 * @throws IncorrectObjectTypeException
+	 *             one of the input objects is not a commit, but the strategy
+	 *             requires it to be a commit.
+	 * @throws IOException
+	 *             one or more sources could not be read, or outputs could not
+	 *             be written to the Repository.
+	 */
+	protected abstract boolean mergeImpl() throws IOException;
+
+	/**
+	 * @return resulting tree, if {@link #merge(AnyObjectId[])} returned true.
+	 */
+	public abstract ObjectId getResultTreeId();
+}