--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hg4j/src/main/java/org/tmatesoft/hg/util/ProgressSupport.java	Tue May 10 10:52:53 2011 +0200
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2011 TMate Software Ltd
+ *  
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * For information on how to redistribute this software under
+ * the terms of a license other than GNU General Public License
+ * contact TMate Software at support@hg4j.com
+ */
+package org.tmatesoft.hg.util;
+
+/**
+ * Mix-in to report progress of a long-running operation
+ *  
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ */
+public interface ProgressSupport {
+
+	public void start(long totalUnits);
+	public void worked(int units);
+	public void done();
+
+	static class Factory {
+
+		/**
+		 * @param target object that might be capable to report progress. Can be <code>null</code>
+		 * @return support object extracted from target or an empty, no-op implementation
+		 */
+		public static ProgressSupport get(Object target) {
+			if (target instanceof ProgressSupport) {
+				return (ProgressSupport) target;
+			}
+			if (target instanceof Adaptable) {
+				ProgressSupport ps = ((Adaptable) target).getAdapter(ProgressSupport.class);
+				if (ps != null) {
+					return ps;
+				}
+			}
+			return new ProgressSupport() {
+				public void start(long totalUnits) {
+				}
+				public void worked(int units) {
+				}
+				public void done() {
+				}
+			};
+		}
+	}
+}