qapi-visit.py: Implement 'base' for unions

This implements the visitor part of base types for unions. Parsed into
QMP, this example schema definition...

    { 'type': 'BlockOptionsBase', 'data': { 'read-only': 'bool' } }
    { 'type': 'BlockOptionsQcow2, 'data': { 'lazy-refcounts': 'bool' } }

    { 'union': 'BlockOptions',
      'base': 'BlockOptionsBase',
      'data': {
          'raw': 'BlockOptionsRaw'
          'qcow2': 'BlockOptionsQcow2'
      } }

...would describe the following JSON object:

    { "type": "qcow2",
      "read-only": true,
      "data": { "lazy-refcounts": false } }

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

1 files changed, 25 insertions, 5 deletions

diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index a337d80f5b..db6fa44b07 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -151,7 +151,13 @@ void visit_type_%(name)s(Visitor *m, %(name)s * obj, const char *name, Error **e
 ''',
                  name=name)
 
-def generate_visit_union(name, members):
+def generate_visit_union(expr):
+
+    name = expr['union']
+    members = expr['data']
+
+    base = expr.get('base')
+
     ret = generate_visit_enum('%sKind' % name, members.keys())
 
     ret += mcgen('''
@@ -164,14 +170,28 @@ void visit_type_%(name)s(Visitor *m, %(name)s ** obj, const char *name, Error **
         visit_start_struct(m, (void **)obj, "%(name)s", name, sizeof(%(name)s), &err);
         if (!err) {
             if (obj && *obj) {
-                visit_type_%(name)sKind(m, &(*obj)->kind, "type", &err);
-                if (!err) {
-                    switch ((*obj)->kind) {
 ''',
                  name=name)
 
+
     push_indent()
     push_indent()
+    push_indent()
+
+    if base:
+        struct = find_struct(base)
+        push_indent()
+        ret += generate_visit_struct_fields("", struct['data'])
+        pop_indent()
+
+    pop_indent()
+    ret += mcgen('''
+        visit_type_%(name)sKind(m, &(*obj)->kind, "type", &err);
+        if (!err) {
+            switch ((*obj)->kind) {
+''',
+                 name=name)
+
     for key in members:
         ret += mcgen('''
             case %(abbrev)s_KIND_%(enum)s:
@@ -368,7 +388,7 @@ for expr in exprs:
         ret = generate_declaration(expr['type'], expr['data'])
         fdecl.write(ret)
     elif expr.has_key('union'):
-        ret = generate_visit_union(expr['union'], expr['data'])
+        ret = generate_visit_union(expr)
         ret += generate_visit_list(expr['union'], expr['data'])
         fdef.write(ret)