This patch allows specifying a discriminator that is an optional member of the base struct. In such a case, a default value must be provided that is used when no value is given.
Signed-off-by: Max Reitz <mre...@redhat.com> --- qapi/introspect.json | 8 ++++++ scripts/qapi/common.py | 57 ++++++++++++++++++++++++++++++++++-------- scripts/qapi/doc.py | 8 ++++-- scripts/qapi/introspect.py | 10 +++++--- scripts/qapi/visit.py | 33 ++++++++++++++++++++++-- tests/qapi-schema/test-qapi.py | 2 ++ 6 files changed, 101 insertions(+), 17 deletions(-) diff --git a/qapi/introspect.json b/qapi/introspect.json index c7f67b7d78..2d7b1e3745 100644 --- a/qapi/introspect.json +++ b/qapi/introspect.json @@ -168,6 +168,13 @@ # @tag: the name of the member serving as type tag. # An element of @members with this name must exist. # +# @default-variant: if the @tag element of @members is optional, this +# is the default value for choosing a variant. Its +# value must be a valid value for @tag. +# Present exactly when @tag is present and the +# associated element of @members is optional. +# (Since: 2.13) +# # @variants: variant members, i.e. additional members that # depend on the type tag's value. Present exactly when # @tag is present. The variants are in no particular order, @@ -181,6 +188,7 @@ { 'struct': 'SchemaInfoObject', 'data': { 'members': [ 'SchemaInfoObjectMember' ], '*tag': 'str', + '*default-variant': 'str', '*variants': [ 'SchemaInfoObjectVariant' ] } } ## diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py index a032cec375..fbf0244f73 100644 --- a/scripts/qapi/common.py +++ b/scripts/qapi/common.py @@ -721,6 +721,7 @@ def check_union(expr, info): name = expr['union'] base = expr.get('base') discriminator = expr.get('discriminator') + default_variant = expr.get('default-variant') members = expr['data'] # Two types of unions, determined by discriminator. @@ -745,16 +746,37 @@ def check_union(expr, info): base_members = find_base_members(base) assert base_members is not None - # The value of member 'discriminator' must name a non-optional - # member of the base struct. + # The value of member 'discriminator' must name a member of + # the base struct. check_name(info, "Discriminator of flat union '%s'" % name, discriminator) - discriminator_type = base_members.get(discriminator) - if not discriminator_type: - raise QAPISemError(info, - "Discriminator '%s' is not a member of base " - "struct '%s'" - % (discriminator, base)) + if default_variant is None: + discriminator_type = base_members.get(discriminator) + if not discriminator_type: + if base_members.get('*' + discriminator) is None: + raise QAPISemError(info, + "Discriminator '%s' is not a member of " + "base struct '%s'" + % (discriminator, base)) + else: + raise QAPISemError(info, + "Default variant must be specified for " + "optional discriminator '%s'" + % discriminator) + else: + discriminator_type = base_members.get('*' + discriminator) + if not discriminator_type: + if base_members.get(discriminator) is None: + raise QAPISemError(info, + "Discriminator '%s' is not a member of " + "base struct '%s'" + % (discriminator, base)) + else: + raise QAPISemError(info, + "Must not specify a default variant for " + "non-optional discriminator '%s'" + % discriminator) + enum_define = enum_types.get(discriminator_type) allow_metas = ['struct'] # Do not allow string discriminator @@ -763,6 +785,15 @@ def check_union(expr, info): "Discriminator '%s' must be of enumeration " "type" % discriminator) + if default_variant is not None: + # Must be a value of the enumeration + if default_variant not in enum_define['data']: + raise QAPISemError(info, + "Default variant '%s' of flat union '%s' is " + "not part of '%s'" + % (default_variant, name, + discriminator_type)) + # Check every branch; don't allow an empty union if len(members) == 0: raise QAPISemError(info, "Union '%s' cannot have empty 'data'" % name) @@ -909,7 +940,7 @@ def check_exprs(exprs): elif 'union' in expr: meta = 'union' check_keys(expr_elem, 'union', ['data'], - ['base', 'discriminator']) + ['base', 'discriminator', 'default-variant']) union_types[expr[meta]] = expr elif 'alternate' in expr: meta = 'alternate' @@ -1335,12 +1366,14 @@ class QAPISchemaObjectTypeMember(QAPISchemaMember): class QAPISchemaObjectTypeVariants(object): - def __init__(self, tag_name, tag_member, variants): + def __init__(self, tag_name, tag_member, default_tag_value, variants): # Flat unions pass tag_name but not tag_member. # Simple unions and alternates pass tag_member but not tag_name. # After check(), tag_member is always set, and tag_name remains # a reliable witness of being used by a flat union. assert bool(tag_member) != bool(tag_name) + # default_tag_value is only passed for flat unions. + assert bool(tag_name) or not bool(default_tag_value) assert (isinstance(tag_name, str) or isinstance(tag_member, QAPISchemaObjectTypeMember)) assert len(variants) > 0 @@ -1348,6 +1381,7 @@ class QAPISchemaObjectTypeVariants(object): assert isinstance(v, QAPISchemaObjectTypeVariant) self._tag_name = tag_name self.tag_member = tag_member + self.default_tag_value = default_tag_value self.variants = variants def set_owner(self, name): @@ -1637,6 +1671,7 @@ class QAPISchema(object): data = expr['data'] base = expr.get('base') tag_name = expr.get('discriminator') + default_tag_value = expr.get('default-variant') tag_member = None if isinstance(base, dict): base = (self._make_implicit_object_type( @@ -1656,6 +1691,7 @@ class QAPISchema(object): QAPISchemaObjectType(name, info, doc, base, members, QAPISchemaObjectTypeVariants(tag_name, tag_member, + default_tag_value, variants))) def _def_alternate_type(self, expr, info, doc): @@ -1668,6 +1704,7 @@ class QAPISchema(object): QAPISchemaAlternateType(name, info, doc, QAPISchemaObjectTypeVariants(None, tag_member, + None, variants))) def _def_command(self, expr, info, doc): diff --git a/scripts/qapi/doc.py b/scripts/qapi/doc.py index 9b312b2c51..91204dc4c6 100644 --- a/scripts/qapi/doc.py +++ b/scripts/qapi/doc.py @@ -160,8 +160,12 @@ def texi_members(doc, what, base, variants, member_func): items += '@item The members of @code{%s}\n' % base.doc_type() if variants: for v in variants.variants: - when = ' when @code{%s} is @t{"%s"}' % ( - variants.tag_member.name, v.name) + if v.name == variants.default_tag_value: + when = ' when @code{%s} is @t{"%s"} or not given' % ( + variants.tag_member.name, v.name) + else: + when = ' when @code{%s} is @t{"%s"}' % ( + variants.tag_member.name, v.name) if v.type.is_implicit(): assert not v.type.base and not v.type.variants for m in v.type.local_members: diff --git a/scripts/qapi/introspect.py b/scripts/qapi/introspect.py index f9e67e8227..2d1d4e320a 100644 --- a/scripts/qapi/introspect.py +++ b/scripts/qapi/introspect.py @@ -142,9 +142,12 @@ const QLitObject %(c_name)s = %(c_string)s; ret['default'] = None return ret - def _gen_variants(self, tag_name, variants): - return {'tag': tag_name, - 'variants': [self._gen_variant(v) for v in variants]} + def _gen_variants(self, tag_name, default_variant, variants): + ret = {'tag': tag_name, + 'variants': [self._gen_variant(v) for v in variants]} + if default_variant: + ret['default-variant'] = default_variant + return ret def _gen_variant(self, variant): return {'case': variant.name, 'type': self._use_type(variant.type)} @@ -163,6 +166,7 @@ const QLitObject %(c_name)s = %(c_string)s; obj = {'members': [self._gen_member(m) for m in members]} if variants: obj.update(self._gen_variants(variants.tag_member.name, + variants.default_tag_value, variants.variants)) self._gen_qlit(name, 'object', obj) diff --git a/scripts/qapi/visit.py b/scripts/qapi/visit.py index 5d72d8936c..ecffc46bd3 100644 --- a/scripts/qapi/visit.py +++ b/scripts/qapi/visit.py @@ -40,10 +40,20 @@ def gen_visit_object_members(name, base, members, variants): void visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp) { Error *err = NULL; - ''', c_name=c_name(name)) + if variants: + ret += mcgen(''' + %(c_type)s %(c_name)s; +''', + c_type=variants.tag_member.type.c_name(), + c_name=c_name(variants.tag_member.name)) + + ret += mcgen(''' + +''') + if base: ret += mcgen(''' visit_type_%(c_type)s_members(v, (%(c_type)s *)obj, &err); @@ -75,8 +85,27 @@ void visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp) ''') if variants: + if variants.default_tag_value is None: + ret += mcgen(''' + %(c_name)s = obj->%(c_name)s; +''', + c_name=c_name(variants.tag_member.name)) + else: + ret += mcgen(''' + if (obj->has_%(c_name)s) { + %(c_name)s = obj->%(c_name)s; + } else { + %(c_name)s = %(enum_const)s; + } +''', + c_name=c_name(variants.tag_member.name), + enum_const=c_enum_const( + variants.tag_member.type.name, + variants.default_tag_value, + variants.tag_member.type.prefix)) + ret += mcgen(''' - switch (obj->%(c_name)s) { + switch (%(c_name)s) { ''', c_name=c_name(variants.tag_member.name)) diff --git a/tests/qapi-schema/test-qapi.py b/tests/qapi-schema/test-qapi.py index c1a144ba29..f2a072b92e 100644 --- a/tests/qapi-schema/test-qapi.py +++ b/tests/qapi-schema/test-qapi.py @@ -56,6 +56,8 @@ class QAPISchemaTestVisitor(QAPISchemaVisitor): def _print_variants(variants): if variants: print(' tag %s' % variants.tag_member.name) + if variants.default_tag_value: + print(' default variant: %s' % variants.default_tag_value) for v in variants.variants: print(' case %s: %s' % (v.name, v.type.name)) -- 2.14.3