# HG changeset patch
# User Lucas Moscovicz <lmoscovicz@fb.com>
# Date 2014-03-14 17:23:54
# Node ID 728438da3090676001565a92156937cf909e00da
# Parent  88aae5382519840620f5a2220589a1956b7cae65

revset: added __add__ method to _addset

This method is intended to duck-type baseset, so we will still have _addset as a
private class but we will be able to return it without wrapping it into an
orderedlazyset or a lazyset.

diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -2425,6 +2425,17 @@ class _addset(object):
             return orderedlazyset(self, filterfunc, ascending=self._ascending)
         return lazyset(self, filterfunc)
 
+    def __add__(self, other):
+        """When both collections are ascending or descending, preserve the order
+        """
+        kwargs = {}
+        if self._ascending is not None:
+            if self.isascending() and other.isascending():
+                kwargs['ascending'] = True
+            if self.isdescending() and other.isdescending():
+                kwargs['ascending'] = False
+        return _addset(self, other, **kwargs)
+
     def _iterator(self):
         """Iterate over both collections without repeating elements