qapi.py: Allow top-level type reference for command definitions

If 'data' for a command definition isn't a dict, but a string, it is
taken as a (struct) type name and the fields of this struct are directly
used as parameters.

This is useful for transactionable commands that can use the same type
definition for both the transaction action and the arguments of the
standalone command.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

scripts/qapi.py

@@ -106,11 +106,18 @@ def parse_schema(fp):
             add_enum(expr_eval['enum'])
         elif expr_eval.has_key('union'):
             add_enum('%sKind' % expr_eval['union'])
+        elif expr_eval.has_key('type'):
+            add_struct(expr_eval)
         exprs.append(expr_eval)
 
     return exprs
 
 def parse_args(typeinfo):
+    if isinstance(typeinfo, basestring):
+        struct = find_struct(typeinfo)
+        assert struct != None
+        typeinfo = struct['data']
+
     for member in typeinfo:
         argname = member
         argentry = typeinfo[member]
@@ -180,6 +187,18 @@ def type_name(name):
     return name
 
 enum_types = []
+struct_types = []
+
+def add_struct(definition):
+    global struct_types
+    struct_types.append(definition)
+
+def find_struct(name):
+    global struct_types
+    for struct in struct_types:
+        if struct['type'] == name:
+            return struct
+    return None
 
 def add_enum(name):
     global enum_types