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authorEric Blake <eblake@redhat.com>2016-03-17 16:48:30 -0600
committerMarkus Armbruster <armbru@redhat.com>2016-03-18 10:29:25 +0100
commit7ce106a96feee4d46bfcdb47127b0935804c9357 (patch)
treef2ec21603adc4d3c7019bcf6f8b5c1bfca8c1d83
parent7599697c66d22ff4c859ba6ccea30e6a9aae6b9b (diff)
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qapi: Emit implicit structs in generated C
We already have several places that want to visit all the members of an implicit object within a larger context (simple union variant, event with anonymous data, command with anonymous arguments struct); and will be adding another one soon (the ability to declare an anonymous base for a flat union). Having a C struct declared for these implicit types, along with a visit_type_FOO_members() helper function, will make for fewer special cases in our generator. We do not, however, need qapi_free_FOO() or visit_type_FOO() functions for implicit types, because they should not be used directly outside of the generated code. This is done by adding a conditional in visit_object_type() for both qapi-types.py and qapi-visit.py based on the object name. The comparison of "name.startswith('q_')" is a bit hacky (it's basically duplicating what .is_implicit() already uses), but beats changing the signature of the visit_object_type() callback to pass a new 'implicit' flag. The hack should be temporary: we are considering adding a future patch that consolidates the narrow visit_object_type(..., base, local_members, variants) and visit_object_type_flat(..., all_members, variants) [where different sets of information are already broken out, and the QAPISchemaObjectType is no longer available] into a broader visit_object_type(obj_type) [where the visitor can query the needed fields from obj_type directly]. Also, now that we WANT to output C code for implicits, we no longer need the visit_needed() filter, leaving 'q_empty' as the only object still needing a special case. Remember, 'q_empty' is the only built-in generated object, which means that without a special case it would be emitted in multiple files (the main qapi-types.h and in qga-qapi-types.h) causing compilation failure due to redefinition. But since it has no members, it's easier to just avoid an attempt to visit that particular type; since gen_object() is called recursively, we also prime the objects_seen set to cover any recursion into the empty type. The patch relies on the changed naming of implicit types in the previous patch. It is a bit unfortunate that the generated struct names and visit_type_FOO_members() don't match normal naming conventions, but it's not too bad, since they will only be used in generated code. The generated code grows substantially in size: the implicit '-wrapper' types must be emitted in qapi-types.h before any union can include an unboxed member of that type. Arguably, the '-args' types could be emitted in a private header for just qapi-visit.c and qmp-marshal.c, rather than polluting qapi-types.h; but adding complexity to the generator to split the output location according to role doesn't seem worth the maintenance costs. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1458254921-17042-6-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
-rw-r--r--scripts/qapi-types.py19
-rw-r--r--scripts/qapi-visit.py23
-rw-r--r--scripts/qapi.py2
3 files changed, 22 insertions, 22 deletions
diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index f194bea..79416b2 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -61,8 +61,7 @@ def gen_object(name, base, members, variants):
ret = ''
if variants:
for v in variants.variants:
- if (isinstance(v.type, QAPISchemaObjectType) and
- not v.type.is_implicit()):
+ if isinstance(v.type, QAPISchemaObjectType):
ret += gen_object(v.type.name, v.type.base,
v.type.local_members, v.type.variants)
@@ -180,6 +179,8 @@ class QAPISchemaGenTypeVisitor(QAPISchemaVisitor):
self._btin = None
def visit_begin(self, schema):
+ # gen_object() is recursive, ensure it doesn't visit the empty type
+ objects_seen.add(schema.the_empty_object_type.name)
self.decl = ''
self.defn = ''
self._fwdecl = ''
@@ -196,11 +197,6 @@ class QAPISchemaGenTypeVisitor(QAPISchemaVisitor):
self.decl = self._btin + self.decl
self._btin = None
- def visit_needed(self, entity):
- # Visit everything except implicit objects
- return not (entity.is_implicit() and
- isinstance(entity, QAPISchemaObjectType))
-
def _gen_type_cleanup(self, name):
self.decl += gen_type_cleanup_decl(name)
self.defn += gen_type_cleanup(name)
@@ -229,11 +225,18 @@ class QAPISchemaGenTypeVisitor(QAPISchemaVisitor):
self._gen_type_cleanup(name)
def visit_object_type(self, name, info, base, members, variants):
+ # Nothing to do for the special empty builtin
+ if name == 'q_empty':
+ return
self._fwdecl += gen_fwd_object_or_array(name)
self.decl += gen_object(name, base, members, variants)
if base:
self.decl += gen_upcast(name, base)
- self._gen_type_cleanup(name)
+ # TODO Worth changing the visitor signature, so we could
+ # directly use rather than repeat type.is_implicit()?
+ if not name.startswith('q_'):
+ # implicit types won't be directly allocated/freed
+ self._gen_type_cleanup(name)
def visit_alternate_type(self, name, info, variants):
self._fwdecl += gen_fwd_object_or_array(name)
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index a712e9a..4923b2e 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -215,13 +215,11 @@ out:
def gen_visit_object(name, base, members, variants):
- ret = gen_visit_object_members(name, base, members, variants)
-
# FIXME: if *obj is NULL on entry, and visit_start_struct() assigns to
# *obj, but then visit_type_FOO_members() fails, we should clean up *obj
# rather than leaving it non-NULL. As currently written, the caller must
# call qapi_free_FOO() to avoid a memory leak of the partial FOO.
- ret += mcgen('''
+ return mcgen('''
void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
{
@@ -245,8 +243,6 @@ out:
''',
c_name=c_name(name))
- return ret
-
class QAPISchemaGenVisitVisitor(QAPISchemaVisitor):
def __init__(self):
@@ -268,11 +264,6 @@ class QAPISchemaGenVisitVisitor(QAPISchemaVisitor):
self.decl = self._btin + self.decl
self._btin = None
- def visit_needed(self, entity):
- # Visit everything except implicit objects
- return not (entity.is_implicit() and
- isinstance(entity, QAPISchemaObjectType))
-
def visit_enum_type(self, name, info, values, prefix):
# Special case for our lone builtin enum type
# TODO use something cleaner than existence of info
@@ -296,9 +287,17 @@ class QAPISchemaGenVisitVisitor(QAPISchemaVisitor):
self.defn += defn
def visit_object_type(self, name, info, base, members, variants):
+ # Nothing to do for the special empty builtin
+ if name == 'q_empty':
+ return
self.decl += gen_visit_members_decl(name)
- self.decl += gen_visit_decl(name)
- self.defn += gen_visit_object(name, base, members, variants)
+ self.defn += gen_visit_object_members(name, base, members, variants)
+ # TODO Worth changing the visitor signature, so we could
+ # directly use rather than repeat type.is_implicit()?
+ if not name.startswith('q_'):
+ # only explicit types need an allocating visit
+ self.decl += gen_visit_decl(name)
+ self.defn += gen_visit_object(name, base, members, variants)
def visit_alternate_type(self, name, info, variants):
self.decl += gen_visit_decl(name)
diff --git a/scripts/qapi.py b/scripts/qapi.py
index f6701f5..96fb216 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1000,7 +1000,6 @@ class QAPISchemaObjectType(QAPISchemaType):
return self.name.startswith('q_')
def c_name(self):
- assert not self.is_implicit()
return QAPISchemaType.c_name(self)
def c_type(self):
@@ -1008,7 +1007,6 @@ class QAPISchemaObjectType(QAPISchemaType):
return c_name(self.name) + pointer_suffix
def c_unboxed_type(self):
- assert not self.is_implicit()
return c_name(self.name)
def json_type(self):