qapi script: support enum type as discriminator in union

By default, any union will automatically generate a enum type as
"[UnionName]Kind" in C code, and it is duplicated when the discriminator
is specified as a pre-defined enum type in schema. After this patch,
the pre-defined enum type will be really used as the switch case
condition in generated C code, if discriminator is an enum field.

Signed-off-by: Wenchao Xia <wenchaoqemu@gmail.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
This commit is contained in:
Wenchao Xia 2014-03-06 17:08:56 -08:00 committed by Luiz Capitulino
parent b0b58195e4
commit bceae7697f
9 changed files with 94 additions and 17 deletions

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@ -123,11 +123,15 @@ And it looks like this on the wire:
Flat union types avoid the nesting on the wire. They are used whenever a
specific field of the base type is declared as the discriminator ('type' is
then no longer generated). The discriminator must always be a string field.
then no longer generated). The discriminator can be a string field or a
predefined enum field. If it is a string field, a hidden enum type will be
generated as "[UNION_NAME]Kind". If it is an enum field, a compile time check
will be done to verify the correctness. It is recommended to use an enum field.
The above example can then be modified as follows:
{ 'enum': 'BlockdevDriver', 'data': [ 'raw', 'qcow2' ] }
{ 'type': 'BlockdevCommonOptions',
'data': { 'driver': 'str', 'readonly': 'bool' } }
'data': { 'driver': 'BlockdevDriver', 'readonly': 'bool' } }
{ 'union': 'BlockdevOptions',
'base': 'BlockdevCommonOptions',
'discriminator': 'driver',

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@ -201,14 +201,21 @@ def generate_union(expr):
base = expr.get('base')
discriminator = expr.get('discriminator')
enum_define = discriminator_find_enum_define(expr)
if enum_define:
discriminator_type_name = enum_define['enum_name']
else:
discriminator_type_name = '%sKind' % (name)
ret = mcgen('''
struct %(name)s
{
%(name)sKind kind;
%(discriminator_type_name)s kind;
union {
void *data;
''',
name=name)
name=name,
discriminator_type_name=discriminator_type_name)
for key in typeinfo:
ret += mcgen('''
@ -389,8 +396,11 @@ for expr in exprs:
fdef.write(generate_enum_lookup(expr['enum'], expr['data']))
elif expr.has_key('union'):
ret += generate_fwd_struct(expr['union'], expr['data']) + "\n"
ret += generate_enum('%sKind' % expr['union'], expr['data'].keys())
fdef.write(generate_enum_lookup('%sKind' % expr['union'], expr['data'].keys()))
enum_define = discriminator_find_enum_define(expr)
if not enum_define:
ret += generate_enum('%sKind' % expr['union'], expr['data'].keys())
fdef.write(generate_enum_lookup('%sKind' % expr['union'],
expr['data'].keys()))
if expr.get('discriminator') == {}:
fdef.write(generate_anon_union_qtypes(expr))
else:

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@ -259,10 +259,16 @@ def generate_visit_union(expr):
assert not base
return generate_visit_anon_union(name, members)
# There will always be a discriminator in the C switch code, by default it
# is an enum type generated silently as "'%sKind' % (name)"
ret = generate_visit_enum('%sKind' % name, members.keys())
disc_type = '%sKind' % (name)
enum_define = discriminator_find_enum_define(expr)
if enum_define:
# Use the enum type as discriminator
ret = ""
disc_type = enum_define['enum_name']
else:
# There will always be a discriminator in the C switch code, by default it
# is an enum type generated silently as "'%sKind' % (name)"
ret = generate_visit_enum('%sKind' % name, members.keys())
disc_type = '%sKind' % (name)
if base:
base_fields = find_struct(base)['data']
@ -298,15 +304,16 @@ void visit_type_%(name)s(Visitor *m, %(name)s ** obj, const char *name, Error **
pop_indent()
if not discriminator:
desc_type = "type"
disc_key = "type"
else:
desc_type = discriminator
disc_key = discriminator
ret += mcgen('''
visit_type_%(name)sKind(m, &(*obj)->kind, "%(type)s", &err);
visit_type_%(disc_type)s(m, &(*obj)->kind, "%(disc_key)s", &err);
if (!err) {
switch ((*obj)->kind) {
''',
name=name, type=desc_type)
disc_type = disc_type,
disc_key = disc_key)
for key in members:
if not discriminator:
@ -517,7 +524,11 @@ for expr in exprs:
ret += generate_visit_list(expr['union'], expr['data'])
fdef.write(ret)
ret = generate_decl_enum('%sKind' % expr['union'], expr['data'].keys())
enum_define = discriminator_find_enum_define(expr)
ret = ""
if not enum_define:
ret = generate_decl_enum('%sKind' % expr['union'],
expr['data'].keys())
ret += generate_declaration(expr['union'], expr['data'])
fdecl.write(ret)
elif expr.has_key('enum'):

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@ -180,6 +180,25 @@ def find_base_fields(base):
return None
return base_struct_define['data']
# Return the discriminator enum define if discriminator is specified as an
# enum type, otherwise return None.
def discriminator_find_enum_define(expr):
base = expr.get('base')
discriminator = expr.get('discriminator')
if not (discriminator and base):
return None
base_fields = find_base_fields(base)
if not base_fields:
return None
discriminator_type = base_fields.get(discriminator)
if not discriminator_type:
return None
return find_enum(discriminator_type)
def check_union(expr, expr_info):
name = expr['union']
base = expr.get('base')
@ -254,11 +273,17 @@ def parse_schema(fp):
add_enum(expr['enum'], expr['data'])
elif expr.has_key('union'):
add_union(expr)
add_enum('%sKind' % expr['union'])
elif expr.has_key('type'):
add_struct(expr)
exprs.append(expr)
# Try again for hidden UnionKind enum
for expr_elem in schema.exprs:
expr = expr_elem['expr']
if expr.has_key('union'):
if not discriminator_find_enum_define(expr):
add_enum('%sKind' % expr['union'])
try:
check_exprs(schema)
except QAPIExprError, e:

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@ -145,7 +145,7 @@ check-qapi-schema-y := $(addprefix tests/qapi-schema/, \
unclosed-list.json unclosed-object.json unclosed-string.json \
duplicate-key.json union-invalid-base.json flat-union-no-base.json \
flat-union-invalid-discriminator.json \
flat-union-invalid-branch-key.json)
flat-union-invalid-branch-key.json flat-union-reverse-define.json)
GENERATED_HEADERS += tests/test-qapi-types.h tests/test-qapi-visit.h tests/test-qmp-commands.h

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@ -0,0 +1 @@
0

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@ -0,0 +1,17 @@
{ 'union': 'TestUnion',
'base': 'TestBase',
'discriminator': 'enum1',
'data': { 'value1': 'TestTypeA',
'value2': 'TestTypeB' } }
{ 'type': 'TestBase',
'data': { 'enum1': 'TestEnum' } }
{ 'enum': 'TestEnum',
'data': [ 'value1', 'value2' ] }
{ 'type': 'TestTypeA',
'data': { 'string': 'str' } }
{ 'type': 'TestTypeB',
'data': { 'integer': 'int' } }

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@ -0,0 +1,9 @@
[OrderedDict([('union', 'TestUnion'), ('base', 'TestBase'), ('discriminator', 'enum1'), ('data', OrderedDict([('value1', 'TestTypeA'), ('value2', 'TestTypeB')]))]),
OrderedDict([('type', 'TestBase'), ('data', OrderedDict([('enum1', 'TestEnum')]))]),
OrderedDict([('enum', 'TestEnum'), ('data', ['value1', 'value2'])]),
OrderedDict([('type', 'TestTypeA'), ('data', OrderedDict([('string', 'str')]))]),
OrderedDict([('type', 'TestTypeB'), ('data', OrderedDict([('integer', 'int')]))])]
[{'enum_name': 'TestEnum', 'enum_values': ['value1', 'value2']}]
[OrderedDict([('type', 'TestBase'), ('data', OrderedDict([('enum1', 'TestEnum')]))]),
OrderedDict([('type', 'TestTypeA'), ('data', OrderedDict([('string', 'str')]))]),
OrderedDict([('type', 'TestTypeB'), ('data', OrderedDict([('integer', 'int')]))])]