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 | 58 ++++++++++++++++++++++++++++------ scripts/qapi/doc.py | 10 ++++-- scripts/qapi/introspect.py | 10 ++++-- scripts/qapi/visit.py | 13 ++++++++ tests/qapi-schema/test-qapi.py | 2 ++ 6 files changed, 86 insertions(+), 15 deletions(-) diff --git a/qapi/introspect.json b/qapi/introspect.json index 3d22166b2b..e4740aa7a0 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 will be a valid value for @tag. +# Present exactly when @tag is present and the +# associated element of @members is optional. +# (Since: 4.0) +# # @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 c89edc0cb0..13fd55d9c9 100644 --- a/scripts/qapi/common.py +++ b/scripts/qapi/common.py @@ -750,6 +750,7 @@ 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. @@ -774,16 +775,37 @@ 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_value = base_members.get(discriminator) - if not discriminator_value: - raise QAPISemError(info, - "Discriminator '%s' is not a member of base " - "struct '%s'" - % (discriminator, base)) + if default_variant is None: + discriminator_value = base_members.get(discriminator) + if not discriminator_value: + 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_value = base_members.get('*' + discriminator) + if not discriminator_value: + 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) + if discriminator_value.get('if'): raise QAPISemError(info, 'The discriminator %s.%s for union %s ' 'must not be conditional' % @@ -796,6 +818,16 @@ 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 not any(value for value in enum_define['data'] + if value['name'] == default_variant): + raise QAPISemError(info, + "Default variant '%s' of flat union '%s' is " + "not part of '%s'" + % (default_variant, name, + discriminator_value['type'])) + # Check every branch; don't allow an empty union if len(members) == 0: raise QAPISemError(info, "Union '%s' cannot have empty 'data'" % name) @@ -976,7 +1008,7 @@ def check_exprs(exprs): elif 'union' in expr: meta = 'union' check_keys(expr_elem, 'union', ['data'], - ['base', 'discriminator', 'if']) + ['base', 'discriminator', 'if', 'default-variant']) normalize_members(expr.get('base')) normalize_members(expr['data']) union_types[expr[meta]] = expr @@ -1431,12 +1463,14 @@ 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 @@ -1444,6 +1478,7 @@ 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): @@ -1773,6 +1808,7 @@ class QAPISchema(object): base = expr.get('base') ifcond = expr.get('if') 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( @@ -1794,6 +1830,7 @@ class QAPISchema(object): QAPISchemaObjectType(name, info, doc, ifcond, base, members, QAPISchemaObjectTypeVariants(tag_name, tag_member, + default_tag_value, variants))) def _def_alternate_type(self, expr, info, doc): @@ -1807,6 +1844,7 @@ class QAPISchema(object): QAPISchemaAlternateType(name, info, doc, ifcond, 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 c03b690161..c7ad23985b 100755 --- a/scripts/qapi/doc.py +++ b/scripts/qapi/doc.py @@ -168,8 +168,14 @@ 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"}%s' % ( - variants.tag_member.name, v.name, texi_if(v.ifcond, " (", ")")) + if v.name == variants.default_tag_value: + when = ' when @code{%s} is @t{"%s"} or not given%s' % ( + variants.tag_member.name, v.name, + texi_if(v.ifcond, " (", ")")) + else: + when = ' when @code{%s} is @t{"%s"}%s' % ( + variants.tag_member.name, v.name, + texi_if(v.ifcond, " (", ")")) 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 f7f2ca07e4..db8af348d2 100644 --- a/scripts/qapi/introspect.py +++ b/scripts/qapi/introspect.py @@ -166,9 +166,12 @@ const QLitObject %(c_name)s = %(c_string)s; ret = (ret, {'if': member.ifcond}) 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)}, @@ -192,6 +195,7 @@ 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, ifcond) diff --git a/scripts/qapi/visit.py b/scripts/qapi/visit.py index 82eab72b21..57eccdfdc2 100644 --- a/scripts/qapi/visit.py +++ b/scripts/qapi/visit.py @@ -77,6 +77,19 @@ void visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp) ret += gen_endif(memb.ifcond) if variants: + if variants.default_tag_value is not None: + ret += mcgen(''' + if (!obj->has_%(c_name)s) { + obj->has_%(c_name)s = true; + obj->%(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) { ''', diff --git a/tests/qapi-schema/test-qapi.py b/tests/qapi-schema/test-qapi.py index d592854601..be223e2cc4 100644 --- a/tests/qapi-schema/test-qapi.py +++ b/tests/qapi-schema/test-qapi.py @@ -66,6 +66,8 @@ 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)) QAPISchemaTestVisitor._print_if(v.ifcond, indent=8) -- 2.20.1