qapi: Anonymous unions

The discriminator for anonymous unions is the data type. This allows to
have a union type that allows both of these:

    { 'file': 'my_existing_block_device_id' }
    { 'file': { 'filename': '/tmp/mydisk.qcow2', 'read-only': true } }

Unions like this are specified in the schema with an empty dict as
discriminator. For this example you could take:

    { 'union': 'BlockRef',
      'discriminator': {},
      'data': { 'definition': 'BlockOptions',
                'reference': 'str' } }
    { 'type': 'ExampleObject',
      'data: { 'file': 'BlockRef' } }

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Kevin Wolf 2013-07-08 16:14:21 +02:00
parent ea66c6d881
commit 69dd62dfd6
10 changed files with 160 additions and 0 deletions

View File

@ -125,6 +125,31 @@ Resulting in this JSON object:
"lazy-refcounts": true } "lazy-refcounts": true }
A special type of unions are anonymous unions. They don't form a dictionary in
the wire format but allow the direct use of different types in their place. As
they aren't structured, they don't have any explicit discriminator but use
the (QObject) data type of their value as an implicit discriminator. This means
that they are restricted to using only one discriminator value per QObject
type. For example, you cannot have two different complex types in an anonymous
union, or two different integer types.
Anonymous unions are declared using an empty dictionary as their discriminator.
The discriminator values never appear on the wire, they are only used in the
generated C code. Anonymous unions cannot have a base type.
{ 'union': 'BlockRef',
'discriminator': {},
'data': { 'definition': 'BlockdevOptions',
'reference': 'str' } }
This example allows using both of the following example objects:
{ "file": "my_existing_block_device_id" }
{ "file": { "driver": "file",
"readonly": false,
'filename': "/tmp/mydisk.qcow2" } }
=== Commands === === Commands ===
Commands are defined by using a list containing three members. The first Commands are defined by using a list containing three members. The first

View File

@ -44,6 +44,7 @@ typedef enum {
QTYPE_QFLOAT, QTYPE_QFLOAT,
QTYPE_QBOOL, QTYPE_QBOOL,
QTYPE_QERROR, QTYPE_QERROR,
QTYPE_MAX,
} qtype_code; } qtype_code;
struct QObject; struct QObject;

View File

@ -32,6 +32,8 @@ struct Visitor
void (*type_enum)(Visitor *v, int *obj, const char *strings[], void (*type_enum)(Visitor *v, int *obj, const char *strings[],
const char *kind, const char *name, Error **errp); const char *kind, const char *name, Error **errp);
void (*get_next_type)(Visitor *v, int *kind, const int *qobjects,
const char *name, Error **errp);
void (*type_int)(Visitor *v, int64_t *obj, const char *name, Error **errp); void (*type_int)(Visitor *v, int64_t *obj, const char *name, Error **errp);
void (*type_bool)(Visitor *v, bool *obj, const char *name, Error **errp); void (*type_bool)(Visitor *v, bool *obj, const char *name, Error **errp);

View File

@ -13,6 +13,7 @@
#ifndef QAPI_VISITOR_CORE_H #ifndef QAPI_VISITOR_CORE_H
#define QAPI_VISITOR_CORE_H #define QAPI_VISITOR_CORE_H
#include "qapi/qmp/qobject.h"
#include "qapi/error.h" #include "qapi/error.h"
#include <stdlib.h> #include <stdlib.h>
@ -42,6 +43,8 @@ void visit_end_list(Visitor *v, Error **errp);
void visit_start_optional(Visitor *v, bool *present, const char *name, void visit_start_optional(Visitor *v, bool *present, const char *name,
Error **errp); Error **errp);
void visit_end_optional(Visitor *v, Error **errp); void visit_end_optional(Visitor *v, Error **errp);
void visit_get_next_type(Visitor *v, int *obj, const int *qtypes,
const char *name, Error **errp);
void visit_type_enum(Visitor *v, int *obj, const char *strings[], void visit_type_enum(Visitor *v, int *obj, const char *strings[],
const char *kind, const char *name, Error **errp); const char *kind, const char *name, Error **errp);
void visit_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp); void visit_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp);

View File

@ -12,6 +12,7 @@
*/ */
#include "qemu-common.h" #include "qemu-common.h"
#include "qapi/qmp/qobject.h"
#include "qapi/qmp/qerror.h" #include "qapi/qmp/qerror.h"
#include "qapi/visitor.h" #include "qapi/visitor.h"
#include "qapi/visitor-impl.h" #include "qapi/visitor-impl.h"
@ -98,6 +99,14 @@ void visit_end_optional(Visitor *v, Error **errp)
} }
} }
void visit_get_next_type(Visitor *v, int *obj, const int *qtypes,
const char *name, Error **errp)
{
if (!error_is_set(errp) && v->get_next_type) {
v->get_next_type(v, obj, qtypes, name, errp);
}
}
void visit_type_enum(Visitor *v, int *obj, const char *strings[], void visit_type_enum(Visitor *v, int *obj, const char *strings[],
const char *kind, const char *name, Error **errp) const char *kind, const char *name, Error **errp)
{ {

View File

@ -208,6 +208,19 @@ static void qmp_input_end_list(Visitor *v, Error **errp)
qmp_input_pop(qiv, errp); qmp_input_pop(qiv, errp);
} }
static void qmp_input_get_next_type(Visitor *v, int *kind, const int *qobjects,
const char *name, Error **errp)
{
QmpInputVisitor *qiv = to_qiv(v);
QObject *qobj = qmp_input_get_object(qiv, name, false);
if (!qobj) {
error_set(errp, QERR_MISSING_PARAMETER, name ? name : "null");
return;
}
*kind = qobjects[qobject_type(qobj)];
}
static void qmp_input_type_int(Visitor *v, int64_t *obj, const char *name, static void qmp_input_type_int(Visitor *v, int64_t *obj, const char *name,
Error **errp) Error **errp)
{ {
@ -317,6 +330,7 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
v->visitor.type_str = qmp_input_type_str; v->visitor.type_str = qmp_input_type_str;
v->visitor.type_number = qmp_input_type_number; v->visitor.type_number = qmp_input_type_number;
v->visitor.start_optional = qmp_input_start_optional; v->visitor.start_optional = qmp_input_start_optional;
v->visitor.get_next_type = qmp_input_get_next_type;
qmp_input_push(v, obj, NULL); qmp_input_push(v, obj, NULL);
qobject_incref(obj); qobject_incref(obj);

View File

@ -260,6 +260,8 @@ static void to_json(const QObject *obj, QString *str, int pretty, int indent)
/* XXX: should QError be emitted? */ /* XXX: should QError be emitted? */
case QTYPE_NONE: case QTYPE_NONE:
break; break;
case QTYPE_MAX:
abort();
} }
} }

View File

@ -150,6 +150,40 @@ typedef enum %(name)s
return lookup_decl + enum_decl return lookup_decl + enum_decl
def generate_anon_union_qtypes(expr):
name = expr['union']
members = expr['data']
ret = mcgen('''
const int %(name)s_qtypes[QTYPE_MAX] = {
''',
name=name)
for key in members:
qapi_type = members[key]
if builtin_type_qtypes.has_key(qapi_type):
qtype = builtin_type_qtypes[qapi_type]
elif find_struct(qapi_type):
qtype = "QTYPE_QDICT"
elif find_union(qapi_type):
qtype = "QTYPE_QDICT"
else:
assert False, "Invalid anonymous union member"
ret += mcgen('''
[ %(qtype)s ] = %(abbrev)s_KIND_%(enum)s,
''',
qtype = qtype,
abbrev = de_camel_case(name).upper(),
enum = c_fun(de_camel_case(key),False).upper())
ret += mcgen('''
};
''')
return ret
def generate_union(expr): def generate_union(expr):
name = expr['union'] name = expr['union']
@ -190,6 +224,12 @@ struct %(name)s
ret += mcgen(''' ret += mcgen('''
}; };
''') ''')
if discriminator == {}:
ret += mcgen('''
extern const int %(name)s_qtypes[];
''',
name=name)
return ret return ret
@ -342,6 +382,8 @@ for expr in exprs:
ret += generate_fwd_struct(expr['union'], expr['data']) + "\n" ret += generate_fwd_struct(expr['union'], expr['data']) + "\n"
ret += generate_enum('%sKind' % expr['union'], expr['data'].keys()) ret += generate_enum('%sKind' % expr['union'], expr['data'].keys())
fdef.write(generate_enum_lookup('%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: else:
continue continue
fdecl.write(ret) fdecl.write(ret)

View File

@ -176,6 +176,49 @@ void visit_type_%(name)s(Visitor *m, %(name)s * obj, const char *name, Error **e
''', ''',
name=name) name=name)
def generate_visit_anon_union(name, members):
ret = mcgen('''
void visit_type_%(name)s(Visitor *m, %(name)s ** obj, const char *name, Error **errp)
{
Error *err = NULL;
if (!error_is_set(errp)) {
visit_start_implicit_struct(m, (void**) obj, sizeof(%(name)s), &err);
visit_get_next_type(m, (int*) &(*obj)->kind, %(name)s_qtypes, name, &err);
switch ((*obj)->kind) {
''',
name=name)
for key in members:
assert (members[key] in builtin_types
or find_struct(members[key])
or find_union(members[key])), "Invalid anonymous union member"
ret += mcgen('''
case %(abbrev)s_KIND_%(enum)s:
visit_type_%(c_type)s(m, &(*obj)->%(c_name)s, name, &err);
break;
''',
abbrev = de_camel_case(name).upper(),
enum = c_fun(de_camel_case(key),False).upper(),
c_type = type_name(members[key]),
c_name = c_fun(key))
ret += mcgen('''
default:
abort();
}
error_propagate(errp, err);
err = NULL;
visit_end_implicit_struct(m, &err);
}
}
''')
return ret
def generate_visit_union(expr): def generate_visit_union(expr):
name = expr['union'] name = expr['union']
@ -184,6 +227,10 @@ def generate_visit_union(expr):
base = expr.get('base') base = expr.get('base')
discriminator = expr.get('discriminator') discriminator = expr.get('discriminator')
if discriminator == {}:
assert not base
return generate_visit_anon_union(name, members)
ret = generate_visit_enum('%sKind' % name, members.keys()) ret = generate_visit_enum('%sKind' % name, members.keys())
if base: if base:

View File

@ -17,6 +17,21 @@ builtin_types = [
'uint8', 'uint16', 'uint32', 'uint64' 'uint8', 'uint16', 'uint32', 'uint64'
] ]
builtin_type_qtypes = {
'str': 'QTYPE_QSTRING',
'int': 'QTYPE_QINT',
'number': 'QTYPE_QFLOAT',
'bool': 'QTYPE_QBOOL',
'int8': 'QTYPE_QINT',
'int16': 'QTYPE_QINT',
'int32': 'QTYPE_QINT',
'int64': 'QTYPE_QINT',
'uint8': 'QTYPE_QINT',
'uint16': 'QTYPE_QINT',
'uint32': 'QTYPE_QINT',
'uint64': 'QTYPE_QINT',
}
def tokenize(data): def tokenize(data):
while len(data): while len(data):
ch = data[0] ch = data[0]