--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/tmatesoft/hg/core/HgChangesetTreeHandler.java	Wed Oct 05 07:13:57 2011 +0200
@@ -0,0 +1,74 @@
+/*
+ * 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.core;
+
+import java.util.Collection;
+
+import org.tmatesoft.hg.util.CancelledException;
+import org.tmatesoft.hg.util.Pair;
+
+/**
+ *
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ */
+public interface HgChangesetTreeHandler {
+	/**
+	 * @param entry access to various pieces of information about current tree node. Instances might be 
+	 * reused across calls and shall not be kept by client's code 
+	 */
+	public void next(HgChangesetTreeHandler.TreeElement entry) throws CancelledException;
+
+	interface TreeElement {
+		/**
+		 * Revision of the revlog being iterated. For example, when walking file history, return value represents file revisions.
+		 * 
+		 * @return revision of the revlog being iterated.
+		 */
+		public Nodeid fileRevision();
+		/**
+		 * @return changeset associated with the current revision
+		 */
+		public HgChangeset changeset();
+
+		/**
+		 * Lightweight alternative to {@link #changeset()}, identifies changeset in which current file node has been modified 
+		 * @return changeset {@link Nodeid} 
+		 */
+		public Nodeid changesetRevision();
+
+		/**
+		 * Node, these are not necessarily in direct relation to parents of changeset from {@link #changeset()} 
+		 * @return changesets that correspond to parents of the current file node, either pair element may be <code>null</code>.
+		 */
+		public Pair<HgChangeset, HgChangeset> parents();
+		
+		/**
+		 * Lightweight alternative to {@link #parents()}, give {@link Nodeid nodeids} only
+		 * @return two values, neither is <code>null</code>, use {@link Nodeid#isNull()} to identify parent not set
+		 */
+		public Pair<Nodeid, Nodeid> parentRevisions();
+
+		public Collection<HgChangeset> children();
+
+		/**
+		 * Lightweight alternative to {@link #children()}.
+		 * @return never <code>null</code>
+		 */
+		public Collection<Nodeid> childRevisions();
+	}
+}
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