Java tutorial
/* * Copyright (C) 2008-2013, Google Inc. * Copyright (C) 2016, Laurent Delaigue <laurent.delaigue@obeo.fr> * 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 java.text.MessageFormat; import org.eclipse.jgit.annotations.Nullable; import org.eclipse.jgit.errors.IncorrectObjectTypeException; import org.eclipse.jgit.errors.NoMergeBaseException; import org.eclipse.jgit.errors.NoMergeBaseException.MergeBaseFailureReason; import org.eclipse.jgit.internal.JGitText; import org.eclipse.jgit.lib.AnyObjectId; import org.eclipse.jgit.lib.NullProgressMonitor; import org.eclipse.jgit.lib.ObjectId; import org.eclipse.jgit.lib.ObjectInserter; import org.eclipse.jgit.lib.ObjectReader; import org.eclipse.jgit.lib.ProgressMonitor; import org.eclipse.jgit.lib.Repository; 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; /** * Instance of a specific {@link org.eclipse.jgit.merge.MergeStrategy} for a * single {@link org.eclipse.jgit.lib.Repository}. */ public abstract class Merger { /** * The repository this merger operates on. * <p> * Null if and only if the merger was constructed with {@link * #Merger(ObjectInserter)}. Callers that want to assume the repo is not null * (e.g. because of a previous check that the merger is not in-core) may use * {@link #nonNullRepo()}. */ @Nullable protected final Repository db; /** Reader to support {@link #walk} and other object loading. */ protected ObjectReader reader; /** A RevWalk for computing merge bases, or listing incoming commits. */ protected RevWalk walk; private ObjectInserter inserter; /** 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; /** * A progress monitor. * * @since 4.2 */ protected ProgressMonitor monitor = NullProgressMonitor.INSTANCE; /** * Create a new merge instance for a repository. * * @param local * the repository this merger will read and write data on. */ protected Merger(Repository local) { if (local == null) { throw new NullPointerException(JGitText.get().repositoryIsRequired); } db = local; inserter = local.newObjectInserter(); reader = inserter.newReader(); walk = new RevWalk(reader); } /** * Create a new in-core merge instance from an inserter. * * @param oi * the inserter to write objects to. Will be closed at the * conclusion of {@code merge}, unless {@code flush} is false. * @since 4.8 */ protected Merger(ObjectInserter oi) { db = null; inserter = oi; reader = oi.newReader(); walk = new RevWalk(reader); } /** * Get the repository this merger operates on. * * @return the repository this merger operates on. */ @Nullable public Repository getRepository() { return db; } /** * Get non-null repository instance * * @return non-null repository instance * @throws java.lang.NullPointerException * if the merger was constructed without a repository. * @since 4.8 */ protected Repository nonNullRepo() { if (db == null) { throw new NullPointerException(JGitText.get().repositoryIsRequired); } return db; } /** * Get an object writer to create objects, writing objects to * {@link #getRepository()} * * @return an object writer to create objects, writing objects to * {@link #getRepository()} (if a repository was provided). */ public ObjectInserter getObjectInserter() { return inserter; } /** * Set the inserter this merger will use to create objects. * <p> * If an inserter was already set on this instance (such as by a prior set, * or a prior call to {@link #getObjectInserter()}), the prior inserter as * well as the in-progress walk will be released. * * @param oi * the inserter instance to use. Must be associated with the * repository instance returned by {@link #getRepository()} (if a * repository was provided). Will be closed at the conclusion of * {@code merge}, unless {@code flush} is false. */ public void setObjectInserter(ObjectInserter oi) { walk.close(); reader.close(); inserter.close(); inserter = oi; reader = oi.newReader(); walk = new RevWalk(reader); } /** * 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 java.io.IOException * one or more sources could not be read, or outputs could not * be written to the Repository. */ public boolean merge(AnyObjectId... tips) throws IOException { return merge(true, tips); } /** * 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. * * @since 3.5 * @param flush * whether to flush and close the underlying object inserter when * finished to store any content-merged blobs and virtual merged * bases; if false, callers are responsible for flushing. * @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 java.io.IOException * one or more sources could not be read, or outputs could not * be written to the Repository. */ public boolean merge(boolean flush, 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]); try { boolean ok = mergeImpl(); if (ok && flush) inserter.flush(); return ok; } finally { if (flush) inserter.close(); reader.close(); } } /** * Get the ID of the commit that was used as merge base for merging * * @return the ID of the commit that was used as merge base for merging, or * null if no merge base was used or it was set manually * @since 3.2 */ public abstract ObjectId getBaseCommitId(); /** * Return the merge base of two commits. * * @param a * the first commit in {@link #sourceObjects}. * @param b * the second commit in {@link #sourceObjects}. * @return the merge base of two commits * @throws org.eclipse.jgit.errors.IncorrectObjectTypeException * one of the input objects is not a commit. * @throws java.io.IOException * objects are missing or multiple merge bases were found. * @since 3.0 */ protected RevCommit getBaseCommit(RevCommit a, RevCommit b) throws IncorrectObjectTypeException, IOException { walk.reset(); walk.setRevFilter(RevFilter.MERGE_BASE); walk.markStart(a); walk.markStart(b); final RevCommit base = walk.next(); if (base == null) return null; final RevCommit base2 = walk.next(); if (base2 != null) { throw new NoMergeBaseException(MergeBaseFailureReason.MULTIPLE_MERGE_BASES_NOT_SUPPORTED, MessageFormat .format(JGitText.get().multipleMergeBasesFor, a.name(), b.name(), base.name(), base2.name())); } return base; } /** * 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 org.eclipse.jgit.errors.IncorrectObjectTypeException * the input object is not a tree. * @throws java.io.IOException * the tree object is not found or cannot be read. */ protected AbstractTreeIterator openTree(AnyObjectId treeId) throws IncorrectObjectTypeException, IOException { return new CanonicalTreeParser(null, reader, treeId); } /** * 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 java.io.IOException * one or more sources could not be read, or outputs could not * be written to the Repository. */ protected abstract boolean mergeImpl() throws IOException; /** * Get resulting tree. * * @return resulting tree, if {@link #merge(AnyObjectId[])} returned true. */ public abstract ObjectId getResultTreeId(); /** * Set a progress monitor. * * @param monitor * Monitor to use, can be null to indicate no progress reporting * is desired. * @since 4.2 */ public void setProgressMonitor(ProgressMonitor monitor) { if (monitor == null) { this.monitor = NullProgressMonitor.INSTANCE; } else { this.monitor = monitor; } } }