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[Qemu-devel] [PATCH 08/26] qapi: Generate a nicer struct for flat unions
From: |
Markus Armbruster |
Subject: |
[Qemu-devel] [PATCH 08/26] qapi: Generate a nicer struct for flat unions |
Date: |
Tue, 4 Aug 2015 11:17:58 +0200 |
The struct generated for a flat union is weird: the members of its
base are at the end, except for the union tag, which is at the
beginning.
Example: qapi-schema-test.json has
{ 'struct': 'UserDefUnionBase',
'data': { 'string': 'str', 'enum1': 'EnumOne' } }
{ 'union': 'UserDefFlatUnion',
'base': 'UserDefUnionBase',
'discriminator': 'enum1',
'data': { 'value1' : 'UserDefA',
'value2' : 'UserDefB',
'value3' : 'UserDefB' } }
We generate:
struct UserDefFlatUnion
{
EnumOne enum1;
union {
void *data;
UserDefA *value1;
UserDefB *value2;
UserDefB *value3;
};
char *string;
};
Change to put all base members at the beginning, unadulterated. Not
only is this easier to understand, it also permits casting the flat
union to its base, if that should become useful.
We now generate:
struct UserDefFlatUnion
{
/* Members inherited from UserDefUnionBase: */
char *string;
EnumOne enum1;
/* Own members: */
union { /* union tag is @enum1 */
void *data;
UserDefA *value1;
UserDefB *value2;
UserDefB *value3;
};
};
Signed-off-by: Markus Armbruster <address@hidden>
---
scripts/qapi-types.py | 38 ++++++++++++++++++++++----------------
1 file changed, 22 insertions(+), 16 deletions(-)
diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index ac8dad3..82141cd 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -200,13 +200,30 @@ def generate_union(expr, meta):
ret = mcgen('''
struct %(name)s
{
- %(discriminator_type_name)s %(discriminator)s;
- union {
+''',
+ name=name)
+ if base:
+ ret += mcgen('''
+ /* Members inherited from %(c_name)s: */
+''',
+ c_name=c_name(base))
+ base_fields = find_struct(base)['data']
+ ret += generate_struct_fields(base_fields)
+ ret += mcgen('''
+ /* Own members: */
+''')
+ else:
+ assert not discriminator
+ ret += mcgen('''
+ %(discriminator_type_name)s kind;
+''',
+ discriminator_type_name=c_name(discriminator_type_name))
+
+ ret += mcgen('''
+ union { /* union tag is @%(c_name)s */
void *data;
''',
- name=name,
- discriminator=c_name(discriminator or 'kind'),
- discriminator_type_name=c_name(discriminator_type_name))
+ c_name=c_name(discriminator or 'kind'))
for key in typeinfo:
ret += mcgen('''
@@ -217,17 +234,6 @@ struct %(name)s
ret += mcgen('''
};
-''')
-
- if base:
- assert discriminator
- base_fields = find_struct(base)['data'].copy()
- del base_fields[discriminator]
- ret += generate_struct_fields(base_fields)
- else:
- assert not discriminator
-
- ret += mcgen('''
};
''')
if meta == 'alternate':
--
2.4.3
- [Qemu-devel] [PATCH 00/26] qapi: Another round of fixes and cleanups, Markus Armbruster, 2015/08/04
- [Qemu-devel] [PATCH 04/26] qapi-event: Clean up how name of enum QAPIEvent is made, Markus Armbruster, 2015/08/04
- [Qemu-devel] [PATCH 01/26] qapi: Clarify docs on including the same file multiple times, Markus Armbruster, 2015/08/04
- [Qemu-devel] [PATCH 05/26] qapi: Reject -p arguments that break qapi-event.py, Markus Armbruster, 2015/08/04
- [Qemu-devel] [PATCH 08/26] qapi: Generate a nicer struct for flat unions,
Markus Armbruster <=
- [Qemu-devel] [PATCH 10/26] qapi-visit: Replace list implicit_structs by set, Markus Armbruster, 2015/08/04
- [Qemu-devel] [PATCH 15/26] qapi: Document shortcoming with union 'data' branch, Markus Armbruster, 2015/08/04
- [Qemu-devel] [PATCH 02/26] qapi: Clean up cgen() and mcgen(), Markus Armbruster, 2015/08/04
- [Qemu-devel] [PATCH 07/26] qapi: Fix generated code when flat union has member 'kind', Markus Armbruster, 2015/08/04
- [Qemu-devel] [PATCH 20/26] qapi: Fix to reject union command and event arguments, Markus Armbruster, 2015/08/04