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<address@hidden>
Reviewed-by: Eric Blake<address@hidden>
---
docs/qapi-code-gen.txt | 8 ++++-
scripts/qapi-types.py | 18 +++++++++---
scripts/qapi-visit.py | 29 +++++++++++++------
scripts/qapi.py | 32 +++++++++++++++++++++-
tests/Makefile | 2 +-
tests/qapi-schema/flat-union-reverse-define.exit | 1 +
tests/qapi-schema/flat-union-reverse-define.json | 17 +++++++++++
tests/qapi-schema/flat-union-reverse-define.out | 9 ++++++
8 files changed, 99 insertions(+), 17 deletions(-)
create mode 100644 tests/qapi-schema/flat-union-reverse-define.err
create mode 100644 tests/qapi-schema/flat-union-reverse-define.exit
create mode 100644 tests/qapi-schema/flat-union-reverse-define.json
create mode 100644 tests/qapi-schema/flat-union-reverse-define.out
diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt
index 0728f36..a2e7921 100644
--- a/docs/qapi-code-gen.txt
+++ b/docs/qapi-code-gen.txt
@@ -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',
diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index 5885bac..10864ef 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -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:
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 0baaf60..45ce3a9 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -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'):
diff --git a/scripts/qapi.py b/scripts/qapi.py
index eebc8a7..0a504c4 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -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 +273,22 @@ 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'):
+ try:
+ enum_define = discriminator_find_enum_define(expr)
+ except QAPIExprError, e:
+ print>>sys.stderr, e
+ exit(1)