[Checkins] SVN: BTrees/branches/py3k/ Factor out common iterator prep.

[Tres Seaver]

Log message for revision 128602:
  Factor out common iterator prep.
  
  Skip looking up unused MERGE WEIGHT for weightedIntersection.

Changed:
  _U  BTrees/branches/py3k/
  U   BTrees/branches/py3k/BTrees/_base.py

-=-
Modified: BTrees/branches/py3k/BTrees/_base.py
===================================================================
--- BTrees/branches/py3k/BTrees/_base.py	2012-12-12 03:15:44 UTC (rev 128601)
+++ BTrees/branches/py3k/BTrees/_base.py	2012-12-12 14:40:47 UTC (rev 128602)
@@ -1272,6 +1272,18 @@
             i2.advance()
     return result
 
+def _prepMergeIterators(o1, o2):
+    MERGE_DEFAULT = getattr(o1, 'MERGE_DEFAULT', None)
+    i1 = _SetIteration(o1, True, MERGE_DEFAULT)
+    i2 = _SetIteration(o2, True, MERGE_DEFAULT)
+    if MERGE_DEFAULT is None:
+        if i1.useValues:
+            if (not i2.useValues):
+                raise TypeError("invalid set operation")
+        else:
+            raise TypeError("invalid set operation")
+    return i1, i2
+
 def weightedUnion(set_type, o1, o2, w1=1, w2=1):
     if o1 is None:
         if o2 is None:
@@ -1279,9 +1291,7 @@
         return w2, o2
     if o2 is None:
         return w1, o1
-    MERGE_DEFAULT = getattr(o1, 'MERGE_DEFAULT', None)
-    i1 = _SetIteration(o1, True, MERGE_DEFAULT)
-    i2 = _SetIteration(o2, True, MERGE_DEFAULT)
+    i1, i2 = _prepMergeIterators(o1, o2)
     MERGE = getattr(o1, 'MERGE', None)
     if MERGE is None and i1.useValues and i2.useValues:
         raise TypeError("invalid set operation")
@@ -1289,12 +1299,6 @@
     if (not i1.useValues) and i2.useValues:
         i1, i2 = i2, i1
         w1, w2 = w2, w1
-    if MERGE_DEFAULT is None:
-        if i1.useValues:
-            if (not i2.useValues):
-                raise TypeError("invalid set operation")
-        else:
-            raise TypeError("invalid set operation")
     _merging = i1.useValues or i2.useValues
     if _merging:
         result = o1._mapping_type()
@@ -1335,22 +1339,13 @@
         return w2, o2
     if o2 is None:
         return w1, o1
-    MERGE_DEFAULT = getattr(o1, 'MERGE_DEFAULT', None)
-    i1 = _SetIteration(o1, True, MERGE_DEFAULT)
-    i2 = _SetIteration(o2, True, MERGE_DEFAULT)
+    i1, i2 = _prepMergeIterators(o1, o2)
     MERGE = getattr(o1, 'MERGE', None)
     if MERGE is None and i1.useValues and i2.useValues:
         raise TypeError("invalid set operation")
-    MERGE_WEIGHT = getattr(o1, 'MERGE_WEIGHT')
     if (not i1.useValues) and i2.useValues:
         i1, i2 = i2, i1
         w1, w2 = w2, w1
-    if MERGE_DEFAULT is None:
-        if i1.useValues:
-            if (not i2.useValues):
-                raise TypeError("invalid set operation")
-        else:
-            raise TypeError("invalid set operation")
     _merging = i1.useValues or i2.useValues
     if _merging:
         result = o1._mapping_type()