# HG changeset patch
# User Lucas Moscovicz <lmoscovicz@fb.com>
# Date 2014-03-14 17:22:51
# Node ID 88aae5382519840620f5a2220589a1956b7cae65
# Parent  180d47e1fb68138adac2e6b523897da25bdc2af7

revset: added __sub__ mehtod to _addset

This method is intended to duck-type baseset, so we will still have _addset as a
private class but now 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
@@ -2419,6 +2419,12 @@ class _addset(object):
             return orderedlazyset(self, filterfunc, ascending=self._ascending)
         return lazyset(self, filterfunc)
 
+    def __sub__(self, other):
+        filterfunc = lambda r: r not in other
+        if self._ascending is not None:
+            return orderedlazyset(self, filterfunc, ascending=self._ascending)
+        return lazyset(self, filterfunc)
+
     def _iterator(self):
         """Iterate over both collections without repeating elements