Add the Checkout command to the Git CLI

The implementation delegates to the CheckoutCommand and
therefore only supports some of the options supported by
the CheckoutCommand.

Signed-off-by: Chris Aniszczyk <caniszczyk@gmail.com>

org.eclipse.jgit.pgm/resources/org/eclipse/jgit/pgm/CLIText.properties

@@ -145,9 +145,11 @@ usage_approveDestructionOfRepository=approve destruction of repository
 usage_beMoreVerbose=be more verbose
 usage_beVerbose=be verbose
 usage_cached=compare against index
+usage_checkout=Checkout a branch to the working tree
 usage_cloneRepositoryIntoNewDir=Clone a repository into a new directory
 usage_configFile=configuration file
 usage_configureTheServiceInDaemonServicename=configure the service in daemon.servicename
+usage_createBranchAndCheckout=create branch and checkout
 usage_deleteBranchEvenIfNotMerged=delete branch (even if not merged)
 usage_deleteFullyMergedBranch=delete fully merged branch
 usage_detectRenames=detect renamed files
@@ -166,6 +168,7 @@ usage_fetchThinPack=fetch thin pack
 usage_filesToAddContentFrom=Files to add content from
 usage_fixAThinPackToBeComplete=fix a thin pack to be complete
 usage_forEachRefOutput=for-each-ref output
+usage_forceCheckout=when switching branches, proceed even if the index or the working tree differs from HEAD
 usage_forceCreateBranchEvenExists=force create branch even exists
 usage_forceReplacingAnExistingTag=force replacing an existing tag
 usage_hostnameOrIpToListenOn=hostname (or ip) to listen on

org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Checkout.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2010, Chris Aniszczyk <caniszczyk@gmail.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.pgm;
+
+import org.eclipse.jgit.api.CheckoutCommand;
+import org.eclipse.jgit.api.Git;
+import org.kohsuke.args4j.Argument;
+import org.kohsuke.args4j.Option;
+
+@Command(common = true, usage = "usage_checkout")
+class Checkout extends TextBuiltin {
+
+	@Option(name = "-b", usage = "usage_createBranchAndCheckout")
+	private boolean createBranch = false;
+
+	@Option(name = "---force", aliases = { "-f" }, usage = "usage_forceCheckout")
+	private boolean force = false;
+
+	@Argument(required = true, metaVar = "metaVar_name", usage = "usage_checkout")
+	private String name;
+
+	@Override
+	protected void run() throws Exception {
+		CheckoutCommand command = new Git(db).checkout();
+		command.setCreateBranch(createBranch);
+		command.setName(name);
+		command.setForce(force);
+		command.call();
+	}
+}