Wenchao Xia <wenchaoq...@gmail.com> 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 <wenchaoq...@gmail.com>
> Reviewed-by: Eric Blake <ebl...@redhat.com>
> ---
> 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)
How can we get QAPIExprError here?
> + if not enum_define:
> + add_enum('%sKind' % expr['union'])
> +
> try:
> check_exprs(schema)
> except QAPIExprError, e:
[...]
