org.eclipse.egit.core/src/org/eclipse/egit/core/internal/CompareCoreUtils.java

   1 /*******************************************************************************
   2  * Copyright (c) 2010, 2013 SAP AG and others.
   3  *
   4  * All rights reserved. This program and the accompanying materials
   5  * are made available under the terms of the Eclipse Public License v1.0
   6  * which accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *
   9  * Contributors:
  10  *    Stefan Lay (SAP AG) - initial implementation
  11  *    Benjamin Muskalla (Tasktop Technologies) - moved into Core for reusability
  12  *******************************************************************************/
  13 package org.eclipse.egit.core.internal;
  14
  15 import java.io.IOException;
  16 import java.util.List;
  17
  18 import org.eclipse.core.resources.IEncodedStorage;
  19 import org.eclipse.core.resources.IFile;
  20 import org.eclipse.core.resources.IResource;
  21 import org.eclipse.core.runtime.CoreException;
  22 import org.eclipse.egit.core.internal.util.ResourceUtil;
  23 import org.eclipse.jgit.diff.DiffEntry;
  24 import org.eclipse.jgit.diff.RenameDetector;
  25 import org.eclipse.jgit.diff.DiffEntry.ChangeType;
  26 import org.eclipse.jgit.lib.Constants;
  27 import org.eclipse.jgit.lib.NullProgressMonitor;
  28 import org.eclipse.jgit.lib.ObjectReader;
  29 import org.eclipse.jgit.lib.Repository;
  30 import org.eclipse.jgit.revwalk.RevCommit;
  31 import org.eclipse.jgit.treewalk.TreeWalk;
  32
  33 /**
  34  * Utility class for compare-related functionality
  35  */
  36 public class CompareCoreUtils {
  37
  38         /**
  39          * Determine the encoding used by Eclipse for the resource which belongs to
  40          * repoPath in the eclipse workspace or null if no resource is found
  41          *
  42          * @param db
  43          *            the repository
  44          * @param repoPath
  45          *            the path in the git repository
  46          * @return the encoding used in eclipse for the resource or null if
  47          *
  48          */
  49         public static String getResourceEncoding(Repository db, String repoPath) {
  50                 if (db.isBare())
  51                         return null;
  52                 IFile resource = ResourceUtil.getFileForLocation(db, repoPath);
  53                 if (resource == null)
  54                         return null;
  55
  56                 return getResourceEncoding(resource);
  57         }
  58
  59         /**
  60          * Determine the encoding used by eclipse for the resource.
  61          *
  62          * @param resource
  63          *            must be an instance of IEncodedStorage
  64          * @return the encoding used in Eclipse for the resource if found or null
  65          */
  66         public static String getResourceEncoding(IResource resource) {
  67                 // Get the encoding for the current version. As a matter of
  68                 // principle one might want to use the eclipse settings for the
  69                 // version we are retrieving as that may be defined by the
  70                 // project settings, but there is no historic API for this.
  71                 String charset;
  72                 IEncodedStorage encodedStorage = ((IEncodedStorage) resource);
  73                 try {
  74                         charset = encodedStorage.getCharset();
  75                         if (charset == null)
  76                                 charset = resource.getParent().getDefaultCharset();
  77                 } catch (CoreException e) {
  78                         charset = Constants.CHARACTER_ENCODING;
  79                 }
  80                 return charset;
  81         }
  82
  83         /**
  84          * Get the {@link DiffEntry} corresponding to a change in file path. If the
  85          * file was renamed, the resulting {@link DiffEntry} will contain the old
  86          * path and blob ID. If the file was only added, null will be returned.
  87          *
  88          * @param repository
  89          * @param newPath
  90          *            path of the file in new commit
  91          * @param newCommit
  92          *            new commit
  93          * @param oldCommit
  94          *            old commit, e.g. parent commit of newCommit
  95          * @param objectReader
  96          *            reader for the repository
  97          * @return the diff entry corresponding to the change for path, or null if
  98          *         none could be found
  99          * @throws IOException
 100          */
 101         public static DiffEntry getChangeDiffEntry(Repository repository, String newPath,
 102                         RevCommit newCommit, RevCommit oldCommit, ObjectReader objectReader)
 103                         throws IOException {
 104                 try (TreeWalk walk = new TreeWalk(objectReader)) {
 105                         walk.setRecursive(true);
 106                         walk.addTree(oldCommit.getTree());
 107                         walk.addTree(newCommit.getTree());
 108
 109                         List<DiffEntry> entries = DiffEntry.scan(walk);
 110
 111                         for (DiffEntry diff : entries) {
 112                                 if (diff.getChangeType() == ChangeType.MODIFY
 113                                                 && newPath.equals(diff.getNewPath()))
 114                                         return diff;
 115                         }
 116
 117                         if (entries.size() < 2)
 118                                 return null;
 119
 120                         RenameDetector detector = new RenameDetector(repository);
 121                         detector.addAll(entries);
 122                         List<DiffEntry> renames = detector.compute(walk.getObjectReader(),
 123                                         NullProgressMonitor.INSTANCE);
 124                         for (DiffEntry diff : renames) {
 125                                 if (diff.getChangeType() == ChangeType.RENAME
 126                                                 && newPath.equals(diff.getNewPath()))
 127                                         return diff;
 128                         }
 129
 130                         return null;
 131                 }
 132         }
 133 }