[Xcb] [PATCH proto 4/7] xcbgen: sumof with nested expression

[Christian Linhart]

Add parser support for sumof with a nested expression.
For example:
	<sumof ref="mylist1">
		<fieldref>bar</fieldref>
	</sumof>

The nested expression is added as the "rhs"-field of the
expression.object.
---
 xcbgen/expr.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/xcbgen/expr.py b/xcbgen/expr.py
index 51e738f..ee2d3fd 100644
--- a/xcbgen/expr.py
+++ b/xcbgen/expr.py
@@ -100,14 +100,20 @@ class Expression(object):
         elif elt.tag == 'enumref':
             self.op = 'enumref'
             self.lenfield_name = (elt.get('ref'), elt.text)
             
         elif elt.tag == 'sumof':
             self.op = 'sumof'
             self.lenfield_name = elt.get('ref')
+            subexpressions = list(elt)
+            if len(subexpressions) > 0:
+                #sumof with a nested expression which is to be evaluated
+                #for each list-element in the context of that list-element.
+                #sumof then returns the sum of the results of these evaluations
+                self.rhs = Expression(subexpressions[0], parent)
 
         else:
             # Notreached
             raise Exception("undefined tag '%s'" % elt.tag)
 
     def fixed_size(self):
         return self.nmemb != None
-- 
2.0.1