--- a/viewer.py	Wed Jul 27 23:58:19 2016 +0800
+++ b/viewer.py	Thu Jul 28 00:41:39 2016 +0800
@@ -24,6 +24,14 @@
 define('debug', metavar='True|False', default=False, type=bool)
 
 
+def isrevrange(rev):
+    if ':' in rev or '..' in rev:
+        return True
+    if re.search(r'(?<!rev)\(.*\)', rev) is not None:
+        return True
+    return False
+
+
 def getinfo(revset):
     output = check_output([HG, 'log', '-R', TESTHGREPO, '-T', 'json', '-r', revset])
     return json.loads(output)
@@ -92,8 +100,12 @@
     def getchangesets(self):
         rev = self.get_argument('rev', 'tip')
         revcount = 120
+        if isrevrange(rev):
+            revset = 'reverse({})'.format(rev)
+        else:
+            revset = '{}:0'.format(rev, revcount)
 
-        return getinfo('first({}:0, {})'.format(rev, revcount))
+        return getinfo('first({}, {})'.format(revset, revcount))
 
     def getlimits(self, marks, changesets=None):
         query = (