Make the resolve merger slightly more sub-classable.

Change-Id: I7d2a90288696ee66887cc01d8a3ec2f6f28a0339
Signed-off-by: Laurent Goubet <laurent.goubet@obeo.fr>

org.eclipse.jgit/src/org/eclipse/jgit/merge/ResolveMerger.java

@@ -85,6 +85,7 @@ import org.eclipse.jgit.revwalk.RevTree;
 import org.eclipse.jgit.treewalk.AbstractTreeIterator;
 import org.eclipse.jgit.treewalk.CanonicalTreeParser;
 import org.eclipse.jgit.treewalk.NameConflictTreeWalk;
+import org.eclipse.jgit.treewalk.TreeWalk;
 import org.eclipse.jgit.treewalk.WorkingTreeIterator;
 import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.FileUtils;
@@ -106,7 +107,12 @@ public class ResolveMerger extends ThreeWayMerger {
 		COULD_NOT_DELETE
 	}
 
-	private NameConflictTreeWalk tw;
+	/**
+	 * The tree walk which we'll iterate over to merge entries.
+	 *
+	 * @since 3.4
+	 */
+	protected NameConflictTreeWalk tw;
 
 	/**
 	 * string versions of a list of commit SHA1s
@@ -115,17 +121,47 @@ public class ResolveMerger extends ThreeWayMerger {
 	 */
 	protected String commitNames[];
 
-	private static final int T_BASE = 0;
+	/**
+	 * Index of the base tree within the {@link #tw tree walk}.
+	 *
+	 * @since 3.4
+	 */
+	protected static final int T_BASE = 0;
 
-	private static final int T_OURS = 1;
+	/**
+	 * Index of our tree in withthe {@link #tw tree walk}.
+	 *
+	 * @since 3.4
+	 */
+	protected static final int T_OURS = 1;
 
-	private static final int T_THEIRS = 2;
+	/**
+	 * Index of their tree within the {@link #tw tree walk}.
+	 *
+	 * @since 3.4
+	 */
+	protected static final int T_THEIRS = 2;
 
-	private static final int T_INDEX = 3;
+	/**
+	 * Index of the index tree within the {@link #tw tree walk}.
+	 *
+	 * @since 3.4
+	 */
+	protected static final int T_INDEX = 3;
 
-	private static final int T_FILE = 4;
+	/**
+	 * Index of the working directory tree within the {@link #tw tree walk}.
+	 *
+	 * @since 3.4
+	 */
+	protected static final int T_FILE = 4;
 
-	private DirCacheBuilder builder;
+	/**
+	 * Builder to update the cache during this merge.
+	 *
+	 * @since 3.4
+	 */
+	protected DirCacheBuilder builder;
 
 	/**
 	 * merge result as tree
@@ -134,19 +170,59 @@ public class ResolveMerger extends ThreeWayMerger {
 	 */
 	protected ObjectId resultTree;
 
-	private List<String> unmergedPaths = new ArrayList<String>();
+	/**
+	 * Paths that could not be merged by this merger because of an unsolvable
+	 * conflict.
+	 *
+	 * @since 3.4
+	 */
+	protected List<String> unmergedPaths = new ArrayList<String>();
 
-	private List<String> modifiedFiles = new LinkedList<String>();
+	/**
+	 * Files modified during this merge operation.
+	 *
+	 * @since 3.4
+	 */
+	protected List<String> modifiedFiles = new LinkedList<String>();
 
-	private Map<String, DirCacheEntry> toBeCheckedOut = new HashMap<String, DirCacheEntry>();
+	/**
+	 * If the merger has nothing to do for a file but check it out at the end of
+	 * the operation, it can be added here.
+	 *
+	 * @since 3.4
+	 */
+	protected Map<String, DirCacheEntry> toBeCheckedOut = new HashMap<String, DirCacheEntry>();
 
-	private List<String> toBeDeleted = new ArrayList<String>();
+	/**
+	 * Paths in this list will be deleted from the local copy at the end of the
+	 * operation.
+	 *
+	 * @since 3.4
+	 */
+	protected List<String> toBeDeleted = new ArrayList<String>();
 
-	private Map<String, MergeResult<? extends Sequence>> mergeResults = new HashMap<String, MergeResult<? extends Sequence>>();
+	/**
+	 * Low-level textual merge results. Will be passed on to the callers in case
+	 * of conflicts.
+	 *
+	 * @since 3.4
+	 */
+	protected Map<String, MergeResult<? extends Sequence>> mergeResults = new HashMap<String, MergeResult<? extends Sequence>>();
 
-	private Map<String, MergeFailureReason> failingPaths = new HashMap<String, MergeFailureReason>();
+	/**
+	 * Paths for which the merge failed altogether.
+	 *
+	 * @since 3.4
+	 */
+	protected Map<String, MergeFailureReason> failingPaths = new HashMap<String, MergeFailureReason>();
 
-	private boolean enterSubtree;
+	/**
+	 * Updated as we merge entries of the tree walk. Tells us whether we should
+	 * recurse into the entry if it is a subtree.
+	 *
+	 * @since 3.4
+	 */
+	protected boolean enterSubtree;
 
 	/**
 	 * Set to true if this merge should work in-memory. The repos dircache and
@@ -277,8 +353,10 @@ public class ResolveMerger extends ThreeWayMerger {
 	 * @throws IOException
 	 * @throws CorruptObjectException
 	 * @throws NoWorkTreeException
+	 * @since 3.4
 	 */
-	private void cleanUp() throws NoWorkTreeException, CorruptObjectException,
+	protected void cleanUp() throws NoWorkTreeException,
+			CorruptObjectException,
 			IOException {
 		if (inCore) {
 			modifiedFiles.clear();
@@ -386,8 +464,9 @@ public class ResolveMerger extends ThreeWayMerger {
 	 * @throws IncorrectObjectTypeException
 	 * @throws CorruptObjectException
 	 * @throws IOException
+	 * @since 3.4
 	 */
-	private boolean processEntry(CanonicalTreeParser base,
+	protected boolean processEntry(CanonicalTreeParser base,
 			CanonicalTreeParser ours, CanonicalTreeParser theirs,
 			DirCacheBuildIterator index, WorkingTreeIterator work)
 			throws MissingObjectException, IncorrectObjectTypeException,
@@ -932,19 +1011,8 @@ public class ResolveMerger extends ThreeWayMerger {
 		if (workingTreeIterator != null)
 			tw.addTree(workingTreeIterator);
 
-		while (tw.next()) {
+		if (!mergeTreeWalk(tw)) {
-			if (!processEntry(
+			return false;
-					tw.getTree(T_BASE, CanonicalTreeParser.class),
-					tw.getTree(T_OURS, CanonicalTreeParser.class),
-					tw.getTree(T_THEIRS, CanonicalTreeParser.class),
-					tw.getTree(T_INDEX, DirCacheBuildIterator.class),
-					(workingTreeIterator == null) ? null : tw.getTree(T_FILE,
-							WorkingTreeIterator.class))) {
-				cleanUp();
-				return false;
-			}
-			if (tw.isSubtree() && enterSubtree)
-				tw.enterSubtree();
 		}
 
 		if (!inCore) {
@@ -976,4 +1044,32 @@ public class ResolveMerger extends ThreeWayMerger {
 			return false;
 		}
 	}
+
+	/**
+	 * Process the given TreeWalk's entries.
+	 *
+	 * @param treeWalk
+	 *            The walk to iterate over.
+	 * @return Whether the trees merged cleanly.
+	 * @throws IOException
+	 * @since 3.4
+	 */
+	protected boolean mergeTreeWalk(TreeWalk treeWalk) throws IOException {
+		boolean hasWorkingTreeIterator = tw.getTreeCount() > T_FILE;
+		while (treeWalk.next()) {
+			if (!processEntry(
+					treeWalk.getTree(T_BASE, CanonicalTreeParser.class),
+					treeWalk.getTree(T_OURS, CanonicalTreeParser.class),
+					treeWalk.getTree(T_THEIRS, CanonicalTreeParser.class),
+					treeWalk.getTree(T_INDEX, DirCacheBuildIterator.class),
+					hasWorkingTreeIterator ? treeWalk.getTree(T_FILE,
+							WorkingTreeIterator.class) : null)) {
+				cleanUp();
+				return false;
+			}
+			if (treeWalk.isSubtree() && enterSubtree)
+				treeWalk.enterSubtree();
+		}
+		return true;
+	}
 }