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[Qemu-block] [PATCH 01/13] qapi: Add default-variant for flat unions
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From: |
Max Reitz |
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Subject: |
[Qemu-block] [PATCH 01/13] qapi: Add default-variant for flat unions |
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Date: |
Wed, 9 May 2018 18:55:18 +0200 |
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 <address@hidden>
---
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
[Qemu-block] [PATCH 02/13] docs/qapi: Document optional discriminators, Max Reitz, 2018/05/09
[Qemu-block] [PATCH 03/13] tests: Add QAPI optional discriminator tests, Max Reitz, 2018/05/09