From 800877bb1639d38ffaebe312a37b61c66bb10c83 Mon Sep 17 00:00:00 2001 From: Anton Nefedov Date: Mon, 18 Jun 2018 11:40:05 +0300 Subject: [PATCH] qapi: allow empty branches in flat unions It often happens that just a few discriminator values imply extra data in a flat union. Existing checks did not make possible to leave other values uncovered. Such cases had to be worked around by either stating a dummy (empty) type or introducing another (subset) discriminator enumeration. Both options create redundant entities in qapi files for little profit. With this patch it is not necessary anymore to add designated union fields for every possible value of a discriminator enumeration. Signed-off-by: Anton Nefedov Message-Id: <1529311206-76847-2-git-send-email-anton.nefedov@virtuozzo.com> Reviewed-by: Markus Armbruster Signed-off-by: Markus Armbruster --- docs/devel/qapi-code-gen.txt | 8 +++++--- scripts/qapi/common.py | 15 ++++++++------- scripts/qapi/types.py | 2 ++ scripts/qapi/visit.py | 19 ++++++++++++++----- tests/Makefile.include | 1 - .../flat-union-incomplete-branch.err | 1 - .../flat-union-incomplete-branch.exit | 1 - .../flat-union-incomplete-branch.json | 9 --------- .../flat-union-incomplete-branch.out | 0 tests/qapi-schema/qapi-schema-test.json | 6 ++++-- tests/qapi-schema/qapi-schema-test.out | 3 ++- 11 files changed, 35 insertions(+), 30 deletions(-) delete mode 100644 tests/qapi-schema/flat-union-incomplete-branch.err delete mode 100644 tests/qapi-schema/flat-union-incomplete-branch.exit delete mode 100644 tests/qapi-schema/flat-union-incomplete-branch.json delete mode 100644 tests/qapi-schema/flat-union-incomplete-branch.out diff --git a/docs/devel/qapi-code-gen.txt b/docs/devel/qapi-code-gen.txt index 1366228b2a..88a70e4d45 100644 --- a/docs/devel/qapi-code-gen.txt +++ b/docs/devel/qapi-code-gen.txt @@ -496,9 +496,11 @@ Resulting in these JSON objects: Notice that in a flat union, the discriminator name is controlled by the user, but because it must map to a base member with enum type, the -code generator can ensure that branches exist for all values of the -enum (although the order of the keys need not match the declaration of -the enum). In the resulting generated C data types, a flat union is +code generator ensures that branches match the existing values of the +enum. The order of the keys need not match the declaration of the enum. +The keys need not cover all possible enum values. Omitted enum values +are still valid branches that add no additional members to the data type. +In the resulting generated C data types, a flat union is represented as a struct with the base members included directly, and then a union of structures for each branch of the struct. diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py index 2462fc0291..4b53f08627 100644 --- a/scripts/qapi/common.py +++ b/scripts/qapi/common.py @@ -779,13 +779,6 @@ def check_union(expr, info): "enum '%s'" % (key, enum_define['enum'])) - # If discriminator is user-defined, ensure all values are covered - if enum_define: - for value in enum_define['data']: - if value not in members.keys(): - raise QAPISemError(info, "Union '%s' data missing '%s' branch" - % (name, value)) - def check_alternate(expr, info): name = expr['alternate'] @@ -1357,6 +1350,14 @@ class QAPISchemaObjectTypeVariants(object): self.tag_member = seen[c_name(self._tag_name)] assert self._tag_name == self.tag_member.name assert isinstance(self.tag_member.type, QAPISchemaEnumType) + if self._tag_name: # flat union + # branches that are not explicitly covered get an empty type + cases = set([v.name for v in self.variants]) + for val in self.tag_member.type.values: + if val.name not in cases: + v = QAPISchemaObjectTypeVariant(val.name, 'q_empty') + v.set_owner(self.tag_member.owner) + self.variants.append(v) for v in self.variants: v.check(schema) # Union names must match enum values; alternate names are diff --git a/scripts/qapi/types.py b/scripts/qapi/types.py index 64d9c0fb37..a599352e59 100644 --- a/scripts/qapi/types.py +++ b/scripts/qapi/types.py @@ -125,6 +125,8 @@ def gen_variants(variants): c_name=c_name(variants.tag_member.name)) for var in variants.variants: + if var.type.name == 'q_empty': + continue ret += mcgen(''' %(c_type)s %(c_name)s; ''', diff --git a/scripts/qapi/visit.py b/scripts/qapi/visit.py index 3c5ea1289e..bdcafb64ee 100644 --- a/scripts/qapi/visit.py +++ b/scripts/qapi/visit.py @@ -81,15 +81,24 @@ void visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp) c_name=c_name(variants.tag_member.name)) for var in variants.variants: - ret += mcgen(''' + case_str = c_enum_const(variants.tag_member.type.name, + var.name, + variants.tag_member.type.prefix) + if var.type.name == 'q_empty': + # valid variant and nothing to do + ret += mcgen(''' + case %(case)s: + break; +''', + case=case_str) + else: + ret += mcgen(''' case %(case)s: visit_type_%(c_type)s_members(v, &obj->u.%(c_name)s, &err); break; ''', - case=c_enum_const(variants.tag_member.type.name, - var.name, - variants.tag_member.type.prefix), - c_type=var.type.c_name(), c_name=c_name(var.name)) + case=case_str, + c_type=var.type.c_name(), c_name=c_name(var.name)) ret += mcgen(''' default: diff --git a/tests/Makefile.include b/tests/Makefile.include index 7c48cfe14e..8b45f01d25 100644 --- a/tests/Makefile.include +++ b/tests/Makefile.include @@ -499,7 +499,6 @@ qapi-schema += flat-union-base-any.json qapi-schema += flat-union-base-union.json qapi-schema += flat-union-clash-member.json qapi-schema += flat-union-empty.json -qapi-schema += flat-union-incomplete-branch.json qapi-schema += flat-union-inline.json qapi-schema += flat-union-int-branch.json qapi-schema += flat-union-invalid-branch-key.json diff --git a/tests/qapi-schema/flat-union-incomplete-branch.err b/tests/qapi-schema/flat-union-incomplete-branch.err deleted file mode 100644 index e826bf0789..0000000000 --- a/tests/qapi-schema/flat-union-incomplete-branch.err +++ /dev/null @@ -1 +0,0 @@ -tests/qapi-schema/flat-union-incomplete-branch.json:6: Union 'TestUnion' data missing 'value2' branch diff --git a/tests/qapi-schema/flat-union-incomplete-branch.exit b/tests/qapi-schema/flat-union-incomplete-branch.exit deleted file mode 100644 index d00491fd7e..0000000000 --- a/tests/qapi-schema/flat-union-incomplete-branch.exit +++ /dev/null @@ -1 +0,0 @@ -1 diff --git a/tests/qapi-schema/flat-union-incomplete-branch.json b/tests/qapi-schema/flat-union-incomplete-branch.json deleted file mode 100644 index 25a411bc83..0000000000 --- a/tests/qapi-schema/flat-union-incomplete-branch.json +++ /dev/null @@ -1,9 +0,0 @@ -# we require all branches of the union to be covered -{ 'enum': 'TestEnum', - 'data': [ 'value1', 'value2' ] } -{ 'struct': 'TestTypeA', - 'data': { 'string': 'str' } } -{ 'union': 'TestUnion', - 'base': { 'type': 'TestEnum' }, - 'discriminator': 'type', - 'data': { 'value1': 'TestTypeA' } } diff --git a/tests/qapi-schema/flat-union-incomplete-branch.out b/tests/qapi-schema/flat-union-incomplete-branch.out deleted file mode 100644 index e69de29bb2..0000000000 diff --git a/tests/qapi-schema/qapi-schema-test.json b/tests/qapi-schema/qapi-schema-test.json index 46c7282945..7b59817f04 100644 --- a/tests/qapi-schema/qapi-schema-test.json +++ b/tests/qapi-schema/qapi-schema-test.json @@ -39,7 +39,7 @@ '*enum1': 'EnumOne' } } # intentional forward reference { 'enum': 'EnumOne', - 'data': [ 'value1', 'value2', 'value3' ] } + 'data': [ 'value1', 'value2', 'value3', 'value4' ] } { 'struct': 'UserDefZero', 'data': { 'integer': 'int' } } @@ -76,7 +76,9 @@ 'discriminator': 'enum1', 'data': { 'value1' : 'UserDefA', 'value2' : 'UserDefB', - 'value3' : 'UserDefB' } } + 'value3' : 'UserDefB' + # 'value4' defaults to empty + } } { 'struct': 'UserDefUnionBase', 'base': 'UserDefZero', diff --git a/tests/qapi-schema/qapi-schema-test.out b/tests/qapi-schema/qapi-schema-test.out index 542a19c407..0dbcdafa3c 100644 --- a/tests/qapi-schema/qapi-schema-test.out +++ b/tests/qapi-schema/qapi-schema-test.out @@ -23,7 +23,7 @@ object UserDefOne base UserDefZero member string: str optional=False member enum1: EnumOne optional=True -enum EnumOne ['value1', 'value2', 'value3'] +enum EnumOne ['value1', 'value2', 'value3', 'value4'] object UserDefZero member integer: int optional=False object UserDefTwoDictDict @@ -52,6 +52,7 @@ object UserDefFlatUnion case value1: UserDefA case value2: UserDefB case value3: UserDefB + case value4: q_empty object UserDefUnionBase base UserDefZero member string: str optional=False