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authorWenchao Xia <wenchaoqemu@gmail.com>2014-03-06 17:08:56 -0800
committerLuiz Capitulino <lcapitulino@redhat.com>2014-03-11 09:07:42 -0400
commitbceae7697ff1711675c26f715b945737bc6849ae (patch)
treeb528a35656db4d66e9c5be5be54edc7cbeb79344 /docs/qapi-code-gen.txt
parentb0b58195e4a3039b6a473124dc27ed707db50240 (diff)
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>
Diffstat (limited to 'docs/qapi-code-gen.txt')
-rw-r--r--docs/qapi-code-gen.txt8
1 files changed, 6 insertions, 2 deletions
diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt
index 0728f36c65..a2e7921601 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',