Add a helper for parsing branch switch info out of a reflog entry

Change-Id: I91c7e08c4afd2562df2226887a933d93c78a0371
Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/ReflogReaderTest.java

@@ -45,6 +45,7 @@
 package org.eclipse.jgit.storage.file;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 
 import java.io.File;
@@ -54,6 +55,7 @@ import java.io.IOException;
 import java.text.SimpleDateFormat;
 import java.util.List;
 
+import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.PersonIdent;
 import org.eclipse.jgit.lib.SampleDataRepositoryTestCase;
@@ -85,6 +87,9 @@ public class ReflogReaderTest extends SampleDataRepositoryTestCase {
 	static byte[] oneLineWithoutComment = "da85355dfc525c9f6f3927b876f379f46ccf826e 3e7549db262d1e836d9bf0af7e22355468f1717c A O Thor Too <authortoo@wri.tr> 1243028200 +0200\n"
 			.getBytes();
 
+	static byte[] switchBranch = "0d43a6890a19fd657faad1c4cfbe3cb1b47851c3 4809df9c0d8bce5b00955563f77c5a9f25aa0d12 A O Thor Too <authortoo@wri.tr> 1315088009 +0200\tcheckout: moving from new/work to master\n"
+			.getBytes();
+
 	@Test
 	public void testReadOneLine() throws Exception {
 		setupReflog("logs/refs/heads/master", oneLine);
@@ -211,6 +216,19 @@ public class ReflogReaderTest extends SampleDataRepositoryTestCase {
 		assertNull(db.getReflogReader("master").getLastEntry());
 	}
 
+	@Test
+	public void testCheckout() throws Exception {
+		setupReflog("logs/HEAD", switchBranch);
+		List<ReflogEntry> entries = db.getReflogReader(Constants.HEAD)
+				.getReverseEntries();
+		assertEquals(1, entries.size());
+		ReflogEntry entry = entries.get(0);
+		CheckoutEntry checkout = entry.parseCheckout();
+		assertNotNull(checkout);
+		assertEquals("master", checkout.getToBranch());
+		assertEquals("new/work", checkout.getFromBranch());
+	}
+
 	private void setupReflog(String logName, byte[] data)
 			throws FileNotFoundException, IOException {
 				File logfile = new File(db.getDirectory(), logName);

org.eclipse.jgit/src/org/eclipse/jgit/storage/file/CheckoutEntry.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2011, Robin Rosenberg <robin.rosenberg@dewire.com>
+ * 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.storage.file;
+
+/**
+ * Parsed information about a checkout.
+ */
+public class CheckoutEntry {
+	static final String CHECKOUT_MOVING_FROM = "checkout: moving from ";
+
+	private String from;
+
+	private String to;
+
+	CheckoutEntry(ReflogEntry reflogEntry) {
+		String comment = reflogEntry.getComment();
+		int p1 = CHECKOUT_MOVING_FROM.length();
+		int p2 = comment.indexOf(" to ", p1);
+		int p3 = comment.length();
+		from = comment.substring(p1,p2);
+		to = comment.substring(p2 + " to ".length(), p3);
+	}
+
+	/**
+	 * @return the name of the branch before checkout
+	 */
+	public String getFromBranch() {
+		return from;
+	}
+
+	/**
+	 * @return the name of the branch after checkout
+	 */
+	public String getToBranch() {
+		return to;
+	}
+}

org.eclipse.jgit/src/org/eclipse/jgit/storage/file/ReflogEntry.java

@@ -99,7 +99,7 @@ public class ReflogEntry {
 	}
 
 	/**
-	 * @return user performin the change
+	 * @return user performing the change
 	 */
 	public PersonIdent getWho() {
 		return who;
@@ -117,4 +117,15 @@ public class ReflogEntry {
 		return "Entry[" + oldId.name() + ", " + newId.name() + ", " + getWho() + ", "
 				+ getComment() + "]";
 	}
+
+	/**
+	 * @return a {@link CheckoutEntry} with parsed information about a branch
+	 *         switch, or null if the entry is not a checkout
+	 */
+	public CheckoutEntry parseCheckout() {
+		if (getComment().startsWith(CheckoutEntry.CHECKOUT_MOVING_FROM))
+			return new CheckoutEntry(this);
+		else
+			return null;
+	}
 }