@@ -329,6 +329,8 @@ class QAPISchemaParser(object):
def find_base_fields(base):
+ if isinstance(base, dict):
+ return base
base_struct_define = find_struct(base)
if not base_struct_define:
return None
@@ -562,9 +564,9 @@ def check_union(expr, expr_info):
# Else, it's a flat union.
else:
- # The object must have a string member 'base'.
+ # The object must have a string or dictionary 'base'.
check_type(expr_info, "'base' for union '%s'" % name,
- base, allow_metas=['struct'])
+ base, allow_dict=True, allow_metas=['struct'])
if not base:
raise QAPIExprError(expr_info,
"Flat union '%s' must have a base"
@@ -1039,6 +1041,8 @@ class QAPISchemaMember(object):
owner = owner[5:]
if owner.endswith('-arg'):
return '(parameter of %s)' % owner[:-4]
+ elif owner.endswith('-base'):
+ return '(base of %s)' % owner[:-5]
else:
assert owner.endswith('-wrapper')
# Unreachable and not implemented
@@ -1323,6 +1327,9 @@ class QAPISchema(object):
base = expr.get('base')
tag_name = expr.get('discriminator')
tag_member = None
+ if isinstance(base, dict):
+ base = (self._make_implicit_object_type(
+ name, info, 'base', self._make_members(base, info)))
if tag_name:
variants = [self._make_variant(key, value)
for (key, value) in data.iteritems()]
@@ -72,13 +72,15 @@ struct %(c_name)s {
''',
c_name=c_name(name))
- if base:
- ret += mcgen('''
+ if base and not base.is_empty():
+ if not base.is_implicit():
+ ret += mcgen('''
/* Members inherited from %(c_name)s: */
''',
- c_name=base.c_name())
+ c_name=base.c_name())
ret += gen_struct_fields(base.members)
- ret += mcgen('''
+ if not base.is_implicit():
+ ret += mcgen('''
/* Own members: */
''')
ret += gen_struct_fields(members)
@@ -238,7 +240,7 @@ class QAPISchemaGenTypeVisitor(QAPISchemaVisitor):
def visit_object_type(self, name, info, base, members, variants):
self._fwdecl += gen_fwd_object_or_array(name)
self.decl += gen_object(name, base, members, variants)
- if base:
+ if base and not base.is_implicit():
self.decl += gen_upcast(name, base)
self._gen_type_cleanup(name)
@@ -41,13 +41,12 @@ static void visit_type_%(c_type)s_fields(Visitor *v, %(c_type)s *obj, Error **er
c_type=typ.c_name())
-def gen_visit_fields_call(typ, direct_name, implicit_name=None):
+def gen_visit_fields_call(typ, direct_name, implicit_name):
ret = ''
assert isinstance(typ, QAPISchemaObjectType)
if typ.is_empty():
pass
elif typ.is_implicit():
- assert implicit_name
assert not typ.variants
ret += gen_visit_fields(typ.members, prefix=implicit_name)
else:
@@ -79,7 +78,8 @@ static void visit_type_%(c_name)s_fields(Visitor *v, %(c_name)s *obj, Error **er
c_name=c_name(name))
if base:
- ret += gen_visit_fields_call(base, '(%s *)obj' % base.c_name())
+ ret += gen_visit_fields_call(base, 'qapi_%s_base(obj)' % c_name(name),
+ 'obj->')
ret += gen_visit_fields(members, prefix='obj->')
@@ -283,7 +283,7 @@ better than open-coding the field to be type 'str'.
=== Union types ===
Usage: { 'union': STRING, 'data': DICT }
-or: { 'union': STRING, 'data': DICT, 'base': STRUCT-NAME,
+or: { 'union': STRING, 'data': DICT, 'base': STRUCT-NAME-OR-DICT,
'discriminator': ENUM-MEMBER-OF-BASE }
Union types are used to let the user choose between several different
@@ -319,13 +319,16 @@ an implicit C enum 'NameKind' is created, corresponding to the union
the union can be named 'max', as this would collide with the implicit
enum. The value for each branch can be of any type.
-A flat union definition specifies a struct as its base, and
-avoids nesting on the wire. All branches of the union must be
-complex types, and the top-level fields of the union dictionary on
-the wire will be combination of fields from both the base type and the
-appropriate branch type (when merging two dictionaries, there must be
-no keys in common). The 'discriminator' field must be the name of an
-enum-typed member of the base struct.
+A flat union definition avoids nesting on the wire, and specifies a
+set of common fields that occur in all variants of the union. The
+'base' key must specifiy either a type name (the type must be a
+struct, not a union), or a dictionary representing an anonymous type.
+All branches of the union must be complex types, and the top-level
+fields of the union dictionary on the wire will be combination of
+fields from both the base type and the appropriate branch type (when
+merging two dictionaries, there must be no keys in common). The
+'discriminator' field must be the name of an enum-typed member of the
+base struct.
The following example enhances the above simple union example by
adding a common field 'readonly', renaming the discriminator to
@@ -333,10 +336,8 @@ something more applicable, and reducing the number of {} required on
the wire:
{ 'enum': 'BlockdevDriver', 'data': [ 'file', 'qcow2' ] }
- { 'struct': 'BlockdevCommonOptions',
- 'data': { 'driver': 'BlockdevDriver', 'readonly': 'bool' } }
{ 'union': 'BlockdevOptions',
- 'base': 'BlockdevCommonOptions',
+ 'base': { 'driver': 'BlockdevDriver', 'readonly': 'bool' },
'discriminator': 'driver',
'data': { 'file': 'FileOptions',
'qcow2': 'Qcow2Options' } }
@@ -354,7 +355,7 @@ code generator can ensure that branches exist for all values of the
enum (although the order of the keys need not match the declaration of
the enum). In the resulting generated C data types, a flat union is
represented as a struct with the base member fields included directly,
-and then a union of structures for each branch of the struct.
+and then a union of pointers to structures for each branch of the struct.
A simple union can always be re-written as a flat union where the base
class has a single member named 'type', and where each branch of the
@@ -365,10 +366,9 @@ union has a struct with a single member named 'data'. That is,
is identical on the wire to:
{ 'enum': 'Enum', 'data': ['one', 'two'] }
- { 'struct': 'Base', 'data': { 'type': 'Enum' } }
{ 'struct': 'Branch1', 'data': { 'data': 'str' } }
{ 'struct': 'Branch2', 'data': { 'data': 'int' } }
- { 'union': 'Flat', 'base': 'Base', 'discriminator': 'type',
+ { 'union': 'Flat': 'base': { 'type': 'Enum' }, 'discriminator': 'type',
'data': { 'one': 'Branch1', 'two': 'Branch2' } }
@@ -1 +1 @@
-tests/qapi-schema/flat-union-bad-base.json:9: 'base' for union 'TestUnion' should be a type name
+tests/qapi-schema/flat-union-bad-base.json:8: 'string' (member of TestTypeA) collides with 'string' (base of TestUnion)
@@ -1,5 +1,4 @@
-# we require the base to be an existing struct
-# TODO: should we allow an anonymous inline base type?
+# we allow anonymous base, but enforce no duplicate keys
{ 'enum': 'TestEnum',
'data': [ 'value1', 'value2' ] }
{ 'struct': 'TestTypeA',
@@ -7,7 +6,7 @@
{ 'struct': 'TestTypeB',
'data': { 'integer': 'int' } }
{ 'union': 'TestUnion',
- 'base': { 'enum1': 'TestEnum', 'kind': 'str' },
+ 'base': { 'enum1': 'TestEnum', 'string': 'str' },
'discriminator': 'enum1',
'data': { 'value1': 'TestTypeA',
'value2': 'TestTypeB' } }
@@ -75,14 +75,10 @@
'base': 'UserDefZero',
'data': { 'string': 'str', 'enum1': 'EnumOne' } }
-{ 'struct': 'UserDefUnionBase2',
- 'base': 'UserDefZero',
- 'data': { 'string': 'str', 'enum1': 'QEnumTwo' } }
-
# this variant of UserDefFlatUnion defaults to a union that uses fields with
# allocated types to test corner cases in the cleanup/dealloc visitor
{ 'union': 'UserDefFlatUnion2',
- 'base': 'UserDefUnionBase2',
+ 'base': { 'string': 'str', 'enum1': 'QEnumTwo' },
'discriminator': 'enum1',
'data': { 'value1' : 'UserDefC', # intentional forward reference
'value2' : 'UserDefB' } }
@@ -8,6 +8,9 @@ object :obj-EVENT_D-arg
member b: str optional=False
member c: str optional=True
member enum3: EnumOne optional=True
+object :obj-UserDefFlatUnion2-base
+ member string: str optional=False
+ member enum1: QEnumTwo optional=False
object :obj-__org.qemu_x-command-arg
member a: __org.qemu_x-EnumList optional=False
member b: __org.qemu_x-StructList optional=False
@@ -121,7 +124,7 @@ object UserDefFlatUnion
case value2: UserDefB
case value3: UserDefB
object UserDefFlatUnion2
- base UserDefUnionBase2
+ base :obj-UserDefFlatUnion2-base
tag enum1
case value1: UserDefC
case value2: UserDefB
@@ -166,10 +169,6 @@ object UserDefUnionBase
base UserDefZero
member string: str optional=False
member enum1: EnumOne optional=False
-object UserDefUnionBase2
- base UserDefZero
- member string: str optional=False
- member enum1: QEnumTwo optional=False
object UserDefZero
member integer: int optional=False
object WrapAlternate
Rather than requiring all flat unions to explicitly create a separate base struct, we can allow the qapi schema to specify the common fields via an inline dictionary. This is similar to how commands can specify an inline anonymous type for its 'data', and matches the fact that our code base already has several flat unions that had to create a separate base type that is used nowhere but in the union. The patch also has to tweak things to avoid calling base.c_name() on an implicit type (since implicit types do not have a name); we already have qapi_FOO_base() which does the trick nicely. Now that anonymous bases are legal, we need to rework the flat-union-bad-base negative test (as previously written, it forms what is now valid QAPI; tweak it to now provide coverage of a new error message path), and add a positive test in qapi-schema-test to use an anonymous base. Note that this patch only allows anonymous bases for flat unions; simple unions are enough syntactic sugar that we do not want to burden them further. Meanwhile, it would be easy to modify qapi.py to also allow an anonymous base for structs; however, there is less of a compelling technical reason to do so, since you can always write the struct to directly contain any members that the anonymous base would have mentioned. Signed-off-by: Eric Blake <eblake@redhat.com> --- v1: rebase and rework to use gen_visit_fields_call(), test new error Previously posted as part of qapi cleanup subset F: v6: avoid redundant error check in gen_visit_union(), rebase to earlier gen_err_check() improvements --- scripts/qapi.py | 11 +++++++++-- scripts/qapi-types.py | 12 +++++++----- scripts/qapi-visit.py | 6 +++--- docs/qapi-code-gen.txt | 28 ++++++++++++++-------------- tests/qapi-schema/flat-union-bad-base.err | 2 +- tests/qapi-schema/flat-union-bad-base.json | 5 ++--- tests/qapi-schema/qapi-schema-test.json | 6 +----- tests/qapi-schema/qapi-schema-test.out | 9 ++++----- 8 files changed, 41 insertions(+), 38 deletions(-)