qapi: New QAPISchemaBranches, QAPISchemaAlternatives

QAPISchemaVariants represents either a union type's branches, or an
alternate type's alternatives.  Much of its code is conditional on
which one it actually is.

Create QAPISchemaBranches for branches, and QAPISchemaAlternatives for
alternatives, both subtypes of QAPISchemaVariants.

Replace QAPISchemaVariants by one of them where possible.  Keep it
only where we actually deal with either of them.

QAPISchemaVariants.__init__() takes @tag_name and @tag_member, where
exactly one must be None: @tag_name for alternatives, @tag_member for
branches.  Let QAPISchemaBranches.__init__() take just @tag_name, and
QAPISchemaAlternatives.__init__() take just @tag_member.

A later patch will move the conditional code to the subtypes.

Signed-off-by: Markus Armbruster <armbru@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/scripts/qapi/types.py b/scripts/qapi/types.py
index c39d054d2c..23cdf3e83e 100644
--- a/scripts/qapi/types.py
+++ b/scripts/qapi/types.py
@@ -23,6 +23,8 @@ from .gen import (
 )
 from .schema import (
     QAPISchema,
+    QAPISchemaAlternatives,
+    QAPISchemaBranches,
     QAPISchemaEnumMember,
     QAPISchemaFeature,
     QAPISchemaIfCond,
@@ -348,7 +350,7 @@ class QAPISchemaGenTypeVisitor(QAPISchemaModularCVisitor):
                           features: List[QAPISchemaFeature],
                           base: Optional[QAPISchemaObjectType],
                           members: List[QAPISchemaObjectTypeMember],
-                          variants: Optional[QAPISchemaVariants]) -> None:
+                          variants: Optional[QAPISchemaBranches]) -> None:
         # Nothing to do for the special empty builtin
         if name == 'q_empty':
             return
@@ -369,7 +371,7 @@ class QAPISchemaGenTypeVisitor(QAPISchemaModularCVisitor):
                              info: Optional[QAPISourceInfo],
                              ifcond: QAPISchemaIfCond,
                              features: List[QAPISchemaFeature],
-                             variants: QAPISchemaVariants) -> None:
+                             variants: QAPISchemaAlternatives) -> None:
         with ifcontext(ifcond, self._genh):
             self._genh.preamble_add(gen_fwd_object_or_array(name))
         self._genh.add(gen_object(name, ifcond, None,