--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/tmatesoft/hg/internal/CsetParamKeeper.java	Tue Apr 09 17:15:30 2013 +0200
@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2013 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.internal;
+
+import static org.tmatesoft.hg.repo.HgRepository.BAD_REVISION;
+import static org.tmatesoft.hg.repo.HgRepository.TIP;
+
+import org.tmatesoft.hg.core.HgBadArgumentException;
+import org.tmatesoft.hg.core.Nodeid;
+import org.tmatesoft.hg.repo.HgInvalidRevisionException;
+import org.tmatesoft.hg.repo.HgRepository;
+
+/**
+ * Common code to keep changelog revision and to perform boundary check.
+ *
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ */
+public class CsetParamKeeper {
+	private final HgRepository repo;
+	private int changelogRevisionIndex = HgRepository.BAD_REVISION;
+	
+	public CsetParamKeeper(HgRepository hgRepo) {
+		repo = hgRepo;
+	}
+	
+	public CsetParamKeeper set(Nodeid changeset) throws HgBadArgumentException {
+		try {
+			set(repo.getChangelog().getRevisionIndex(changeset));
+		} catch (HgInvalidRevisionException ex) {
+			throw new HgBadArgumentException("Can't find revision", ex).setRevision(changeset);
+		}
+		return this;
+	}
+	
+	public CsetParamKeeper set(int changelogRevIndex) throws HgBadArgumentException {
+		int lastCsetIndex = repo.getChangelog().getLastRevision();
+		if (changelogRevIndex == HgRepository.TIP) {
+			changelogRevIndex = lastCsetIndex;
+		}
+		if (changelogRevIndex < 0 || changelogRevIndex > lastCsetIndex) {
+			throw new HgBadArgumentException(String.format("Bad revision index %d, value from [0..%d] expected", changelogRevIndex, lastCsetIndex), null).setRevisionIndex(changelogRevIndex);
+		}
+		doSet(changelogRevIndex);
+		return this;
+	}
+	
+	public void doSet(int changelogRevIndex) {
+		changelogRevisionIndex = changelogRevIndex;
+	}
+
+	/**
+	 * @return the value set, or {@link HgRepository#BAD_REVISION} otherwise
+	 */
+	public int get() {
+		return changelogRevisionIndex;
+	}
+
+	/**
+	 * @param defaultRevisionIndex value to return when no revision was set, may be {@link HgRepository#TIP} which gets translated to real index if used
+	 * @return changelog revision index if set, or defaultRevisionIndex value otherwise
+	 */
+	public int get(int defaultRevisionIndex) {
+		// XXX perhaps, shall translate other predefined constants (like WORKING COPY) here, too (e.g. for HgRevertCommand)
+		if (changelogRevisionIndex != BAD_REVISION || changelogRevisionIndex != TIP) {
+			return changelogRevisionIndex;
+		}
+		if (changelogRevisionIndex == TIP || defaultRevisionIndex == TIP) {
+			return repo.getChangelog().getLastRevision();
+		}
+		return defaultRevisionIndex;
+	}
+}