Add BranchConfig helper for access to branch config section

Getting the name of the remote-tracking branch given a branch is not so
easy to get right. This class provides a way to do that and could be
used for more branch config related things (e.g. in PullCommand).

Change-Id: I896a2384217936c8b672df8b81c9599f5c350458
Signed-off-by: Robin Stocker <robin@nibor.org>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/BranchConfigTest.java

@@ -0,0 +1,116 @@
+/*
+ * Copyright (C) 2011, Robin Stocker <robin@nibor.org>
+ * 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.lib;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+import org.eclipse.jgit.errors.ConfigInvalidException;
+import org.junit.Test;
+
+public class BranchConfigTest {
+
+	@Test
+	public void getRemoteTrackingBranchShouldHandleNormalCase() {
+		Config c = parse("" //
+				+ "[remote \"origin\"]\n"
+				+ "  fetch = +refs/heads/*:refs/remotes/origin/*\n"
+				+ "[branch \"master\"]\n"
+				+ "  remote = origin\n"
+				+ "  merge = refs/heads/master\n");
+
+		BranchConfig branchConfig = new BranchConfig(c, "master");
+		assertEquals("refs/remotes/origin/master",
+				branchConfig.getRemoteTrackingBranch());
+	}
+
+	@Test
+	public void getRemoteTrackingBranchShouldHandleOtherMapping() {
+		Config c = parse("" //
+				+ "[remote \"test\"]\n"
+				+ "  fetch = +refs/foo/*:refs/remotes/origin/foo/*\n"
+				+ "  fetch = +refs/heads/*:refs/remotes/origin/*\n"
+				+ "  fetch = +refs/other/*:refs/remotes/origin/other/*\n"
+				+ "[branch \"master\"]\n"
+				+ "  remote = test\n"
+				+ "  merge = refs/foo/master\n" + "\n");
+
+		BranchConfig branchConfig = new BranchConfig(c, "master");
+		assertEquals("refs/remotes/origin/foo/master",
+				branchConfig.getRemoteTrackingBranch());
+	}
+
+	@Test
+	public void getRemoteTrackingBranchShouldReturnNullWithoutFetchSpec() {
+		Config c = parse("" //
+				+ "[remote \"origin\"]\n"
+				+ "  fetch = +refs/heads/onlyone:refs/remotes/origin/onlyone\n"
+				+ "[branch \"master\"]\n"
+				+ "  remote = origin\n"
+				+ "  merge = refs/heads/master\n");
+		BranchConfig branchConfig = new BranchConfig(c, "master");
+		assertNull(branchConfig.getRemoteTrackingBranch());
+	}
+
+	@Test
+	public void getRemoteTrackingBranchShouldReturnNullWithoutMergeBranch() {
+		Config c = parse("" //
+				+ "[remote \"origin\"]\n"
+				+ "  fetch = +refs/heads/onlyone:refs/remotes/origin/onlyone\n"
+				+ "[branch \"master\"]\n"
+				+ "  remote = origin\n");
+		BranchConfig branchConfig = new BranchConfig(c, "master");
+		assertNull(branchConfig.getRemoteTrackingBranch());
+	}
+
+	private Config parse(final String content) {
+		final Config c = new Config(null);
+		try {
+			c.fromText(content);
+		} catch (ConfigInvalidException e) {
+			throw new RuntimeException(e);
+		}
+		return c;
+	}
+}

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

@@ -0,0 +1,114 @@
+/*
+ * Copyright (C) 2011, Robin Stocker <robin@nibor.org>
+ * 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.lib;
+
+import java.net.URISyntaxException;
+
+import org.eclipse.jgit.transport.RefSpec;
+import org.eclipse.jgit.transport.RemoteConfig;
+
+/**
+ * Branch section of a Git configuration file.
+ */
+public class BranchConfig {
+
+	private final Config config;
+	private final String branchName;
+
+	/**
+	 * Create a new branch config, which will read configuration from config
+	 * about specified branch.
+	 *
+	 * @param config
+	 *            the config to read from
+	 * @param branchName
+	 *            the short branch name of the section to read
+	 */
+	public BranchConfig(final Config config, String branchName) {
+		this.config = config;
+		this.branchName = branchName;
+	}
+
+	/**
+	 * @return the full remote-tracking branch name or <code>null</code> if it
+	 *         could not be determined
+	 */
+	public String getRemoteTrackingBranch() {
+		String remote = getRemote();
+		String mergeRef = getMergeBranch();
+		if (remote == null || mergeRef == null)
+			return null;
+
+		RemoteConfig remoteConfig;
+		try {
+			remoteConfig = new RemoteConfig(config, remote);
+		} catch (URISyntaxException e) {
+			return null;
+		}
+		for (RefSpec refSpec : remoteConfig.getFetchRefSpecs()) {
+			if (refSpec.matchSource(mergeRef)) {
+				RefSpec expanded = refSpec.expandFromSource(mergeRef);
+				return expanded.getDestination();
+			}
+		}
+		return null;
+	}
+
+	private String getRemote() {
+		String remoteName = config.getString(
+				ConfigConstants.CONFIG_BRANCH_SECTION, branchName,
+				ConfigConstants.CONFIG_KEY_REMOTE);
+		if (remoteName == null)
+			return Constants.DEFAULT_REMOTE_NAME;
+		else
+			return remoteName;
+	}
+
+	private String getMergeBranch() {
+		String mergeRef = config.getString(
+				ConfigConstants.CONFIG_BRANCH_SECTION, branchName,
+				ConfigConstants.CONFIG_KEY_MERGE);
+		return mergeRef;
+	}
+}