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Re: [Qemu-devel] [PATCH V7 07/11] qapi script: support pre-defined enum
From: |
Wenchao Xia |
Subject: |
Re: [Qemu-devel] [PATCH V7 07/11] qapi script: support pre-defined enum type as discriminator in union |
Date: |
Fri, 21 Feb 2014 08:17:56 +0800 |
User-agent: |
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 |
δΊ 2014/2/21 0:38, Markus Armbruster ει:
> Wenchao Xia <address@hidden> writes:
>
>> 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>
>> ---
>> docs/qapi-code-gen.txt | 8 ++++++--
>> scripts/qapi-types.py | 20 ++++++++++++++++----
>> scripts/qapi-visit.py | 27 ++++++++++++++++++++-------
>> scripts/qapi.py | 13 ++++++++++++-
>> 4 files changed, 54 insertions(+), 14 deletions(-)
>>
>> 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 656a9a0..4098c60 100644
>> --- a/scripts/qapi-types.py
>> +++ b/scripts/qapi-types.py
>> @@ -201,14 +201,22 @@ def generate_union(expr):
>> base = expr.get('base')
>> discriminator = expr.get('discriminator')
>>
>> + expr_elem = {'expr': expr}
>> + enum_define = discriminator_find_enum_define(expr_elem)
>
> expr_elem has no fp, line. What if discriminator_find_enum_define
> throws a QAPIExprError?
>
It shouldn't happen, since all error check happens in parse_schema().
> More of the same below.
>
>> + 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 +397,12 @@ 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()))
>> + expr_elem = {'expr': expr}
>> + enum_define = discriminator_find_enum_define(expr_elem)
>> + if not enum_define:
>> + ret += generate_enum('%sKind' % expr['union'],
>> expr['data'].keys())
>> + fdef.write(generate_enum_lookup('%sKind' % expr['union'],
>> + expr['data'].keys()))
>
> Generate the implicit enum only when we don't have an explicit enum
> discriminator. Good.
>
>> 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 87e6df7..08685a7 100644
>> --- a/scripts/qapi-visit.py
>> +++ b/scripts/qapi-visit.py
>> @@ -260,10 +260,17 @@ 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())
>> - discriminator_type_name = '%sKind' % (name)
>> + expr_elem = {'expr': expr}
>> + enum_define = discriminator_find_enum_define(expr_elem)
>> + if enum_define:
>> + # Use the predefined enum type as discriminator
>> + ret = ""
>> + discriminator_type_name = 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())
>> + discriminator_type_name = '%sKind' % (name)
>
> Generate the visit of the discriminator only when we don't have an
> explicit enum discriminator (which gets visited elsewhere already).
> Good.
>
>>
>> if base:
>> base_fields = find_struct(base)['data']
>> @@ -303,11 +310,12 @@ void visit_type_%(name)s(Visitor *m, %(name)s ** obj,
>> const char *name, Error **
>> else:
>> desc_type = discriminator
>> ret += mcgen('''
>> - visit_type_%(name)sKind(m, &(*obj)->kind, "%(type)s", &err);
>> + visit_type_%(discriminator_type_name)s(m, &(*obj)->kind,
>> "%(type)s", &err);
>
> Another long line due to very long identifier.
>
Will improve.
>> if (!err) {
>> switch ((*obj)->kind) {
>> ''',
>> - name=name, type=desc_type)
>> + discriminator_type_name=discriminator_type_name,
>> + type=desc_type)
>>
>> for key in members:
>> if not discriminator:
>> @@ -519,7 +527,12 @@ 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())
>> + expr_elem = {'expr': expr}
>> + enum_define = discriminator_find_enum_define(expr_elem)
>> + ret = ""
>> + if not enum_define:
>> + ret = generate_decl_enum('%sKind' % expr['union'],
>> + expr['data'].keys())
>
> Generate the visitor for the implicit enum only when we don't have an
> explicit enum discriminator (which has its own visitor already). Good.
>
>> 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 130dced..2a5eb59 100644
>> --- a/scripts/qapi.py
>> +++ b/scripts/qapi.py
>> @@ -250,11 +250,22 @@ 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_elem)
>> + except QAPIExprError, e:
>> + print >>sys.stderr, e
>> + exit(1)
>> + if not enum_define:
>> + add_enum('%sKind' % expr['union'])
>> +
>> try:
>> check_exprs(schema)
>> except QAPIExprError, e:
>
> I guess you move this into its own loop because when base types are used
> before they're defined, or an enum type is used for a discriminator
> before it's defined, then discriminator_find_enum_define() complains.
> Correct?
>
Exactly, which allow enum define after usage in schema.
[Qemu-devel] [PATCH V7 02/11] qapi script: add check for duplicated key, Wenchao Xia, 2014/02/20
[Qemu-devel] [PATCH V7 06/11] qapi script: use same function to generate enum string, Wenchao Xia, 2014/02/20
[Qemu-devel] [PATCH V7 05/11] qapi script: code move for generate_enum_name(), Wenchao Xia, 2014/02/20
[Qemu-devel] [PATCH V7 03/11] qapi-script: remember line number in schema parsing, Wenchao Xia, 2014/02/20