add "stable" parameter to enums
This parameter gives a hint to the backend that the enum members have the same
value in all OpenFlow versions. It's enforced when generating the unified IR.
The stable parameter is added to the BSN port/vlan/vrf stats extensions.
diff --git a/loxi_front_end/parser.py b/loxi_front_end/parser.py
index 4a465f7..fbf476d 100644
--- a/loxi_front_end/parser.py
+++ b/loxi_front_end/parser.py
@@ -68,7 +68,7 @@
s('}') - s(';')
# Enums
-enum_param_name = kw("wire_type") | kw("bitmask") | kw("complete")
+enum_param_name = kw("wire_type") | kw("bitmask") | kw("complete") | kw("stable")
enum_param = P.Group(enum_param_name - s('=') - word)
enum_param_list = P.Forward()
enum_param_list << enum_param + P.Optional(s(',') + P.Optional(enum_param_list))