Move FormatActivator.start()/stop() to a separate class

This makes the functionality of registering all formats from the
org.eclipse.jgit.archive package available in contexts where
FormatActivator cannot be built because the OSGi core framework is not
readily available to build against.

Change-Id: If8e3487e933783a7e12f8e1838cbfe0b5862ce80

org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/ArchiveFormats.java

@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2013 Google Inc.
+ * 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.archive;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.eclipse.jgit.api.ArchiveCommand;
+
+/**
+ * Registers all format types from the org.eclipse.jgit.archive
+ * package for use via the ArchiveCommand API.
+ *
+ * See {@link FormatActivator} for an OSGi bundle activator
+ * that performs the same registration automatically.
+ */
+public class ArchiveFormats {
+	private static final List<String> myFormats = new ArrayList<String>();
+
+	private static final void register(String name, ArchiveCommand.Format<?> fmt) {
+		myFormats.add(name);
+		ArchiveCommand.registerFormat(name, fmt);
+	}
+
+	/**
+	 * Register all included archive formats so they can be used
+	 * as arguments to the ArchiveCommand.setFormat() method.
+	 *
+	 * Should not be called twice without a call to stop() in between.
+	 * Not thread-safe.
+	 */
+	public static void registerAll() {
+		register("tar", new TarFormat());
+		register("tgz", new TgzFormat());
+		register("txz", new TxzFormat());
+		register("zip", new ZipFormat());
+	}
+
+	/**
+	 * Clean up by deregistering all formats that were registered
+	 * by registerAll().
+	 *
+	 * Not thread-safe.
+	 */
+	public static void unregisterAll() {
+		for (String name : myFormats) {
+			ArchiveCommand.unregisterFormat(name);
+		}
+		myFormats.clear();
+	}
+}

org.eclipse.jgit.archive/src/org/eclipse/jgit/archive/FormatActivator.java

@@ -42,10 +42,6 @@
  */
 package org.eclipse.jgit.archive;
 
-import java.util.ArrayList;
-import java.util.List;
-
-import org.eclipse.jgit.api.ArchiveCommand;
 import org.osgi.framework.BundleActivator;
 import org.osgi.framework.BundleContext;
 
@@ -58,51 +54,13 @@ import org.osgi.framework.BundleContext;
  * when the package is loaded as an OSGi bundle (and the corresponding
  * deregistration happens when the bundle is unloaded, to avoid
  * leaks).
- *
- * The static start() and stop() methods allow registering the same
- * list of formats manually in cases where OSGi bundle activation
- * cannot be used.
  */
 public class FormatActivator implements BundleActivator {
-	private static final List<String> myFormats = new ArrayList<String>();
-
-	private static final void register(String name, ArchiveCommand.Format<?> fmt) {
-		myFormats.add(name);
-		ArchiveCommand.registerFormat(name, fmt);
-	}
-
-	/**
-	 * Register all included archive formats so they can be used
-	 * as arguments to the ArchiveCommand.setFormat() method.
-	 *
-	 * Should not be called twice without a call to stop() in between.
-	 * Not thread-safe.
-	 */
-	public static void start() {
-		register("tar", new TarFormat());
-		register("tgz", new TgzFormat());
-		register("txz", new TxzFormat());
-		register("zip", new ZipFormat());
-	}
-
-	/**
-	 * Clean up by deregistering all formats that were registered
-	 * by start().
-	 *
-	 * Not thread-safe.
-	 */
-	public static void stop() {
-		for (String name : myFormats) {
-			ArchiveCommand.unregisterFormat(name);
-		}
-		myFormats.clear();
-	}
-
 	public void start(BundleContext context) throws Exception {
-		start();
+		ArchiveFormats.registerAll();
 	}
 
 	public void stop(BundleContext context) throws Exception {
-		stop();
+		ArchiveFormats.unregisterAll();
 	}
 }

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

@@ -46,7 +46,7 @@ package org.eclipse.jgit.pgm;
 import org.eclipse.jgit.api.ArchiveCommand;
 import org.eclipse.jgit.api.Git;
 import org.eclipse.jgit.api.errors.GitAPIException;
-import org.eclipse.jgit.archive.FormatActivator;
+import org.eclipse.jgit.archive.ArchiveFormats;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.pgm.TextBuiltin;
 import org.eclipse.jgit.pgm.internal.CLIText;
@@ -56,7 +56,7 @@ import org.kohsuke.args4j.Option;
 @Command(common = true, usage = "usage_archive")
 class Archive extends TextBuiltin {
 	static {
-		FormatActivator.start();
+		ArchiveFormats.registerAll();
 	}
 
 	@Argument(index = 0, metaVar = "metaVar_treeish")