Replace manual peel loops with RevWalk.peel

Instead of peeling things by hand in application level code, defer
the peeling logic into RevWalk's new peel utility method.

Change-Id: Idabd10dc41502e782f6a2eeb56f09566b97775a8
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

org.eclipse.jgit/src/org/eclipse/jgit/lib/RefDirectory.java

@@ -409,12 +409,8 @@ public class RefDirectory extends RefDatabase {
 		RevObject obj = rw.parseAny(leaf.getObjectId());
 		ObjectIdRef newLeaf;
 		if (obj instanceof RevTag) {
-			do {
-				obj = rw.parseAny(((RevTag) obj).getObject());
-			} while (obj instanceof RevTag);
-
 			newLeaf = new ObjectIdRef.PeeledTag(leaf.getStorage(), leaf
-					.getName(), leaf.getObjectId(), obj.copy());
+					.getName(), leaf.getObjectId(), rw.peel(obj).copy());
 		} else {
 			newLeaf = new ObjectIdRef.PeeledNonTag(leaf.getStorage(), leaf
 					.getName(), leaf.getObjectId());

org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RevWalk.java

@@ -659,11 +659,7 @@ public class RevWalk implements Iterable<RevCommit> {
 	public RevCommit parseCommit(final AnyObjectId id)
 			throws MissingObjectException, IncorrectObjectTypeException,
 			IOException {
-		RevObject c = parseAny(id);
-		while (c instanceof RevTag) {
-			c = ((RevTag) c).getObject();
-			parseHeaders(c);
-		}
+		RevObject c = peel(parseAny(id));
 		if (!(c instanceof RevCommit))
 			throw new IncorrectObjectTypeException(id.toObjectId(),
 					Constants.TYPE_COMMIT);
@@ -690,11 +686,7 @@ public class RevWalk implements Iterable<RevCommit> {
 	public RevTree parseTree(final AnyObjectId id)
 			throws MissingObjectException, IncorrectObjectTypeException,
 			IOException {
-		RevObject c = parseAny(id);
-		while (c instanceof RevTag) {
-			c = ((RevTag) c).getObject();
-			parseHeaders(c);
-		}
+		RevObject c = peel(parseAny(id));
 
 		final RevTree t;
 		if (c instanceof RevCommit)
@@ -802,6 +794,29 @@ public class RevWalk implements Iterable<RevCommit> {
 		obj.parseBody(this);
 	}
 
+	/**
+	 * Peel back annotated tags until a non-tag object is found.
+	 *
+	 * @param obj
+	 *            the starting object.
+	 * @return If {@code obj} is not an annotated tag, {@code obj}. Otherwise
+	 *         the first non-tag object that {@code obj} references. The
+	 *         returned object's headers have been parsed.
+	 * @throws MissingObjectException
+	 *             a referenced object cannot be found.
+	 * @throws IOException
+	 *             a pack file or loose object could not be read.
+	 */
+	public RevObject peel(RevObject obj) throws MissingObjectException,
+			IOException {
+		while (obj instanceof RevTag) {
+			parseHeaders(obj);
+			obj = ((RevTag) obj).getObject();
+		}
+		parseHeaders(obj);
+		return obj;
+	}
+
 	/**
 	 * Create a new flag for application use during walking.
 	 * <p>

org.eclipse.jgit/src/org/eclipse/jgit/transport/ReceivePack.java

@@ -84,7 +84,6 @@ import org.eclipse.jgit.revwalk.RevBlob;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevFlag;
 import org.eclipse.jgit.revwalk.RevObject;
-import org.eclipse.jgit.revwalk.RevTag;
 import org.eclipse.jgit.revwalk.RevTree;
 import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.transport.ReceiveCommand.Result;
@@ -818,8 +817,7 @@ public class ReceivePack {
 			ow.markUninteresting(o);
 
 			if (checkReferencedIsReachable && !baseObjects.isEmpty()) {
-				while (o instanceof RevTag)
-					o = ((RevTag) o).getObject();
+				o = ow.peel(o);
 				if (o instanceof RevCommit)
 					o = ((RevCommit) o).getTree();
 				if (o instanceof RevTree)

org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java

@@ -56,6 +56,7 @@ import java.util.Map;
 import java.util.Set;
 
 import org.eclipse.jgit.JGitText;
+import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.errors.PackProtocolException;
 import org.eclipse.jgit.lib.NullProgressMonitor;
 import org.eclipse.jgit.lib.ObjectId;
@@ -393,11 +394,15 @@ public class UploadPack {
 			}
 			if (!o.has(ADVERTISED))
 				throw new PackProtocolException(MessageFormat.format(JGitText.get().notValid, id.name()));
-			want(o);
+			try {
+				want(o);
+			} catch (IOException e) {
+				throw new PackProtocolException(MessageFormat.format(JGitText.get().notValid, id.name()), e);
+			}
 		}
 	}
 
-	private void want(RevObject o) {
+	private void want(RevObject o) throws MissingObjectException, IOException {
 		if (!o.has(WANT)) {
 			o.add(WANT);
 			wantAll.add(o);
@@ -406,9 +411,7 @@ public class UploadPack {
 				wantCommits.add((RevCommit) o);
 
 			else if (o instanceof RevTag) {
-				do {
-					o = ((RevTag) o).getObject();
-				} while (o instanceof RevTag);
+				o = walk.peel(o);
 				if (o instanceof RevCommit)
 					want(o);
 			}