Look at block-job-change command: we have to specify both 'id' to chose
the job to operate on and 'type' for QAPI union be parsed. But for user
this looks redundant: when we specify 'id', QEMU should be able to get
corresponding job's type.
This commit brings such a possibility: just specify some Enum type as
'discriminator', and define a function somewhere with prototype
bool YourUnionType_mapper(YourUnionType *, EnumType *out, Error **errp)
Further commits will use this functionality to upgrade block-job-change
interface and introduce some new interfaces.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxxx>
---
scripts/qapi/introspect.py | 5 +++-
scripts/qapi/schema.py | 50 +++++++++++++++++++++++---------------
scripts/qapi/types.py | 3 ++-
scripts/qapi/visit.py | 43 ++++++++++++++++++++++++++------
4 files changed, 73 insertions(+), 28 deletions(-)
diff --git a/scripts/qapi/introspect.py b/scripts/qapi/introspect.py
index 67c7d89aae..04d8d424f5 100644
--- a/scripts/qapi/introspect.py
+++ b/scripts/qapi/introspect.py
@@ -336,7 +336,10 @@ def visit_object_type_flat(self, name: str, info: Optional[QAPISourceInfo],
'members': [self._gen_object_member(m) for m in members]
}
if variants:
- obj['tag'] = variants.tag_member.name
+ if variants.tag_member:
+ obj['tag'] = variants.tag_member.name
+ else:
+ obj['discriminator-type'] = variants.tag_type.name
obj['variants'] = [self._gen_variant(v) for v in variants.variants]
self._gen_tree(name, 'object', obj, ifcond, features)
diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
index 8ba5665bc6..0efe8d815c 100644
--- a/scripts/qapi/schema.py
+++ b/scripts/qapi/schema.py
@@ -585,16 +585,16 @@ def visit(self, visitor):
class QAPISchemaVariants:
- def __init__(self, tag_name, info, tag_member, variants):
+ def __init__(self, discriminator, info, tag_member, variants):
# Unions pass tag_name but not tag_member.
# Alternates pass tag_member but not tag_name.
# After check(), tag_member is always set.
- assert bool(tag_member) != bool(tag_name)
- assert (isinstance(tag_name, str) or
+ assert bool(tag_member) != bool(discriminator)
+ assert (isinstance(discriminator, str) or
isinstance(tag_member, QAPISchemaObjectTypeMember))
for v in variants:
assert isinstance(v, QAPISchemaVariant)
- self._tag_name = tag_name
+ self.discriminator = discriminator
self.info = info
self.tag_member = tag_member
self.variants = variants
@@ -604,16 +604,24 @@ def set_defined_in(self, name):
v.set_defined_in(name)
def check(self, schema, seen):
- if self._tag_name: # union
- self.tag_member = seen.get(c_name(self._tag_name))
+ self.tag_type = None
+
+ if self.discriminator: # assume union with type discriminator
+ self.tag_type = schema.lookup_type(self.discriminator)
+
+ # union with discriminator field
+ if self.discriminator and not self.tag_type:
+ tag_name = self.discriminator
+ self.tag_member = seen.get(c_name(tag_name))
+ self.tag_type = self.tag_member.type
base = "'base'"
# Pointing to the base type when not implicit would be
# nice, but we don't know it here
- if not self.tag_member or self._tag_name != self.tag_member.name:
+ if not self.tag_member or tag_name != self.tag_member.name:
raise QAPISemError(
self.info,
"discriminator '%s' is not a member of %s"
- % (self._tag_name, base))
+ % (tag_name, base))
# Here we do:
base_type = schema.lookup_type(self.tag_member.defined_in)
assert base_type
@@ -623,29 +631,33 @@ def check(self, schema, seen):
raise QAPISemError(
self.info,
"discriminator member '%s' of %s must be of enum type"
- % (self._tag_name, base))
+ % (tag_name, base))
if self.tag_member.optional:
raise QAPISemError(
self.info,
"discriminator member '%s' of %s must not be optional"
- % (self._tag_name, base))
+ % (tag_name, base))
if self.tag_member.ifcond.is_present():
raise QAPISemError(
self.info,
"discriminator member '%s' of %s must not be conditional"
- % (self._tag_name, base))
- else: # alternate
+ % (tag_name, base))
+ elif not self.tag_type: # alternate
assert isinstance(self.tag_member.type, QAPISchemaEnumType)
assert not self.tag_member.optional
assert not self.tag_member.ifcond.is_present()
- if self._tag_name: # union
+
+ if self.tag_type: # union
# branches that are not explicitly covered get an empty type
cases = {v.name for v in self.variants}
- for m in self.tag_member.type.members:
+ for m in self.tag_type.members:
if m.name not in cases:
v = QAPISchemaVariant(m.name, self.info,
'q_empty', m.ifcond)
- v.set_defined_in(self.tag_member.defined_in)
+ if self.tag_member:
+ v.set_defined_in(self.tag_member.defined_in)
+ else:
+ v.set_defined_in(self.tag_type.name)
self.variants.append(v)
if not self.variants:
raise QAPISemError(self.info, "union has no branches")
@@ -654,11 +666,11 @@ def check(self, schema, seen):
# Union names must match enum values; alternate names are
# checked separately. Use 'seen' to tell the two apart.
if seen:
- if v.name not in self.tag_member.type.member_names():
+ if v.name not in self.tag_type.member_names():
raise QAPISemError(
self.info,
"branch '%s' is not a value of %s"
- % (v.name, self.tag_member.type.describe()))
+ % (v.name, self.tag_type.describe()))
if not isinstance(v.type, QAPISchemaObjectType):
raise QAPISemError(
self.info,
@@ -1116,7 +1128,7 @@ def _make_variant(self, case, typ, ifcond, info):
def _def_union_type(self, expr: QAPIExpression):
name = expr['union']
base = expr['base']
- tag_name = expr['discriminator']
+ discriminator = expr['discriminator']
data = expr['data']
assert isinstance(data, dict)
info = expr.info
@@ -1136,7 +1148,7 @@ def _def_union_type(self, expr: QAPIExpression):
QAPISchemaObjectType(name, info, expr.doc, ifcond, features,
base, members,
QAPISchemaVariants(
- tag_name, info, None, variants)))
+ discriminator, info, None, variants)))
def _def_alternate_type(self, expr: QAPIExpression):
name = expr['alternate']
diff --git a/scripts/qapi/types.py b/scripts/qapi/types.py
index c39d054d2c..13021e3f82 100644
--- a/scripts/qapi/types.py
+++ b/scripts/qapi/types.py
@@ -230,7 +230,8 @@ def gen_variants(variants: QAPISchemaVariants) -> str:
ret = mcgen('''
union { /* union tag is @%(c_name)s */
''',
- c_name=c_name(variants.tag_member.name))
+ c_name=c_name(variants.tag_member.name if variants.tag_member
+ else variants.tag_type.name))
for var in variants.variants:
if var.type.name == 'q_empty':
diff --git a/scripts/qapi/visit.py b/scripts/qapi/visit.py
index c56ea4d724..fbe7ae071d 100644
--- a/scripts/qapi/visit.py
+++ b/scripts/qapi/visit.py
@@ -60,6 +60,13 @@ def gen_visit_members_decl(name: str) -> str:
c_name=c_name(name))
+def gen_visit_members_tag_mapper_decl(name: str, tag_type: str) -> str:
+ return mcgen('''
+
+bool %(c_name)s_mapper(%(c_name)s *obj, %(tag_type)s *tag, Error **errp);
+ ''', c_name=c_name(name), tag_type=c_name(tag_type))
+
+
def gen_visit_object_members(name: str,
base: Optional[QAPISchemaObjectType],
members: List[QAPISchemaObjectTypeMember],
@@ -83,6 +90,12 @@ def gen_visit_object_members(name: str,
ret += memb.ifcond.gen_endif()
ret += sep
+ if variants:
+ ret += mcgen('''
+ %(c_name)s tag;
+''',
+ c_name=c_name(variants.tag_type.name))
+
if base:
ret += mcgen('''
if (!visit_type_%(c_type)s_members(v, (%(c_type)s *)obj, errp)) {
@@ -132,17 +145,29 @@ def gen_visit_object_members(name: str,
ret += memb.ifcond.gen_endif()
if variants:
- tag_member = variants.tag_member
- assert isinstance(tag_member.type, QAPISchemaEnumType)
+ tag_type = variants.tag_type
+ assert isinstance(tag_type, QAPISchemaEnumType)
- ret += mcgen('''
- switch (obj->%(c_name)s) {
+ if variants.tag_member:
+ ret += mcgen('''
+ tag = obj->%(c_name)s;
''',
- c_name=c_name(tag_member.name))
+ c_name=c_name(variants.tag_member.name))
+ else:
+ ret += mcgen('''
+ if (!%(c_name)s_mapper(obj, &tag, errp)) {
+ return false;
+ }
+''',
+ c_name=c_name(name))
+
+ ret += mcgen('''
+ switch (tag) {
+''')
for var in variants.variants:
- case_str = c_enum_const(tag_member.type.name, var.name,
- tag_member.type.prefix)
+ case_str = c_enum_const(tag_type.name, var.name,
+ tag_type.prefix)
ret += var.ifcond.gen_if()
if var.type.name == 'q_empty':
# valid variant and nothing to do
@@ -400,6 +425,10 @@ def visit_object_type(self,
return
with ifcontext(ifcond, self._genh, self._genc):
self._genh.add(gen_visit_members_decl(name))
+ if variants and variants.tag_type:
+ self._genh.add(
+ gen_visit_members_tag_mapper_decl(name,
+ variants.tag_type.name))
self._genc.add(gen_visit_object_members(name, base,
members, variants))
# TODO Worth changing the visitor signature, so we could
--
2.34.1
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