Simple unions were carrying a special case that hid their 'data' QMP member from the resulting C struct, via the hack method QAPISchemaObjectTypeVariant.simple_union_type(). But by using the work we started by unboxing flat union and alternate branches, coupled with the ability to visit the members of an implicit type, we can now expose the simple union's implicit type in qapi-types.h: | struct q_obj_ImageInfoSpecificQCow2_wrapper { | ImageInfoSpecificQCow2 *data; | }; | | struct q_obj_ImageInfoSpecificVmdk_wrapper { | ImageInfoSpecificVmdk *data; | }; ... | struct ImageInfoSpecific { | ImageInfoSpecificKind type; | union { /* union tag is @type */ | void *data; |- ImageInfoSpecificQCow2 *qcow2; |- ImageInfoSpecificVmdk *vmdk; |+ q_obj_ImageInfoSpecificQCow2_wrapper qcow2; |+ q_obj_ImageInfoSpecificVmdk_wrapper vmdk; | } u; | }; Doing this removes asymmetry between QAPI's QMP side and its C side (both sides now expose 'data'), and means that the treatment of a simple union as sugar for a flat union is now equivalent in both languages (previously the two approaches used a different layer of dereferencing, where the simple union could be converted to a flat union with equivalent C layout but different {} on the wire, or to an equivalent QMP wire form but with different C representation). Using the implicit type also lets us get rid of the simple_union_type() hack. Of course, now all clients of simple unions have to adjust from using su->u.member to using su->u.member.data; while this touches a number of files in the tree, some earlier cleanup patches helped minimize the change to the initialization of a temporary variable rather than every single member access. The generated qapi-visit.c code is also affected by the layout change: |@@ -7393,10 +7393,10 @@ void visit_type_ImageInfoSpecific_member | } | switch (obj->type) { | case IMAGE_INFO_SPECIFIC_KIND_QCOW2: |- visit_type_ImageInfoSpecificQCow2(v, "data", &obj->u.qcow2, &err); |+ visit_type_q_obj_ImageInfoSpecificQCow2_wrapper_members(v, &obj->u.qcow2, &err); | break; | case IMAGE_INFO_SPECIFIC_KIND_VMDK: |- visit_type_ImageInfoSpecificVmdk(v, "data", &obj->u.vmdk, &err); |+ visit_type_q_obj_ImageInfoSpecificVmdk_wrapper_members(v, &obj->u.vmdk, &err); | break; | default: | abort(); Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1458254921-17042-13-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
307 lines
8.1 KiB
Python
307 lines
8.1 KiB
Python
#
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# QAPI types generator
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#
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# Copyright IBM, Corp. 2011
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# Copyright (c) 2013-2016 Red Hat Inc.
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#
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# Authors:
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# Anthony Liguori <aliguori@us.ibm.com>
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# Markus Armbruster <armbru@redhat.com>
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#
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# This work is licensed under the terms of the GNU GPL, version 2.
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# See the COPYING file in the top-level directory.
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from qapi import *
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# variants must be emitted before their container; track what has already
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# been output
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objects_seen = set()
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def gen_fwd_object_or_array(name):
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return mcgen('''
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typedef struct %(c_name)s %(c_name)s;
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''',
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c_name=c_name(name))
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def gen_array(name, element_type):
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return mcgen('''
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struct %(c_name)s {
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%(c_name)s *next;
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%(c_type)s value;
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};
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''',
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c_name=c_name(name), c_type=element_type.c_type())
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def gen_struct_members(members):
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ret = ''
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for memb in members:
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if memb.optional:
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ret += mcgen('''
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bool has_%(c_name)s;
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''',
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c_name=c_name(memb.name))
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ret += mcgen('''
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%(c_type)s %(c_name)s;
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''',
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c_type=memb.type.c_type(), c_name=c_name(memb.name))
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return ret
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def gen_object(name, base, members, variants):
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if name in objects_seen:
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return ''
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objects_seen.add(name)
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ret = ''
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if variants:
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for v in variants.variants:
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if isinstance(v.type, QAPISchemaObjectType):
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ret += gen_object(v.type.name, v.type.base,
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v.type.local_members, v.type.variants)
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ret += mcgen('''
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struct %(c_name)s {
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''',
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c_name=c_name(name))
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if base:
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ret += mcgen('''
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/* Members inherited from %(c_name)s: */
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''',
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c_name=base.c_name())
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ret += gen_struct_members(base.members)
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ret += mcgen('''
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/* Own members: */
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''')
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ret += gen_struct_members(members)
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if variants:
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ret += gen_variants(variants)
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# Make sure that all structs have at least one member; this avoids
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# potential issues with attempting to malloc space for zero-length
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# structs in C, and also incompatibility with C++ (where an empty
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# struct is size 1).
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if not (base and base.members) and not members and not variants:
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ret += mcgen('''
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char qapi_dummy_for_empty_struct;
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''')
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ret += mcgen('''
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};
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''')
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return ret
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def gen_upcast(name, base):
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# C makes const-correctness ugly. We have to cast away const to let
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# this function work for both const and non-const obj.
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return mcgen('''
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static inline %(base)s *qapi_%(c_name)s_base(const %(c_name)s *obj)
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{
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return (%(base)s *)obj;
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}
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''',
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c_name=c_name(name), base=base.c_name())
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def gen_variants(variants):
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ret = mcgen('''
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union { /* union tag is @%(c_name)s */
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''',
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c_name=c_name(variants.tag_member.name))
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for var in variants.variants:
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ret += mcgen('''
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%(c_type)s %(c_name)s;
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''',
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c_type=var.type.c_unboxed_type(),
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c_name=c_name(var.name))
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ret += mcgen('''
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} u;
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''')
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return ret
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def gen_type_cleanup_decl(name):
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ret = mcgen('''
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void qapi_free_%(c_name)s(%(c_name)s *obj);
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''',
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c_name=c_name(name))
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return ret
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def gen_type_cleanup(name):
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ret = mcgen('''
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void qapi_free_%(c_name)s(%(c_name)s *obj)
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{
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QapiDeallocVisitor *qdv;
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Visitor *v;
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if (!obj) {
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return;
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}
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qdv = qapi_dealloc_visitor_new();
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v = qapi_dealloc_get_visitor(qdv);
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visit_type_%(c_name)s(v, NULL, &obj, NULL);
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qapi_dealloc_visitor_cleanup(qdv);
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}
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''',
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c_name=c_name(name))
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return ret
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class QAPISchemaGenTypeVisitor(QAPISchemaVisitor):
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def __init__(self):
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self.decl = None
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self.defn = None
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self._fwdecl = None
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self._btin = None
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def visit_begin(self, schema):
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# gen_object() is recursive, ensure it doesn't visit the empty type
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objects_seen.add(schema.the_empty_object_type.name)
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self.decl = ''
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self.defn = ''
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self._fwdecl = ''
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self._btin = guardstart('QAPI_TYPES_BUILTIN')
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def visit_end(self):
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self.decl = self._fwdecl + self.decl
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self._fwdecl = None
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# To avoid header dependency hell, we always generate
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# declarations for built-in types in our header files and
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# simply guard them. See also do_builtins (command line
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# option -b).
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self._btin += guardend('QAPI_TYPES_BUILTIN')
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self.decl = self._btin + self.decl
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self._btin = None
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def _gen_type_cleanup(self, name):
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self.decl += gen_type_cleanup_decl(name)
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self.defn += gen_type_cleanup(name)
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def visit_enum_type(self, name, info, values, prefix):
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# Special case for our lone builtin enum type
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# TODO use something cleaner than existence of info
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if not info:
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self._btin += gen_enum(name, values, prefix)
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if do_builtins:
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self.defn += gen_enum_lookup(name, values, prefix)
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else:
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self._fwdecl += gen_enum(name, values, prefix)
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self.defn += gen_enum_lookup(name, values, prefix)
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def visit_array_type(self, name, info, element_type):
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if isinstance(element_type, QAPISchemaBuiltinType):
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self._btin += gen_fwd_object_or_array(name)
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self._btin += gen_array(name, element_type)
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self._btin += gen_type_cleanup_decl(name)
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if do_builtins:
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self.defn += gen_type_cleanup(name)
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else:
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self._fwdecl += gen_fwd_object_or_array(name)
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self.decl += gen_array(name, element_type)
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self._gen_type_cleanup(name)
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def visit_object_type(self, name, info, base, members, variants):
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# Nothing to do for the special empty builtin
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if name == 'q_empty':
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return
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self._fwdecl += gen_fwd_object_or_array(name)
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self.decl += gen_object(name, base, members, variants)
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if base:
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self.decl += gen_upcast(name, base)
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# TODO Worth changing the visitor signature, so we could
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# directly use rather than repeat type.is_implicit()?
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if not name.startswith('q_'):
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# implicit types won't be directly allocated/freed
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self._gen_type_cleanup(name)
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def visit_alternate_type(self, name, info, variants):
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self._fwdecl += gen_fwd_object_or_array(name)
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self.decl += gen_object(name, None, [variants.tag_member], variants)
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self._gen_type_cleanup(name)
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# If you link code generated from multiple schemata, you want only one
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# instance of the code for built-in types. Generate it only when
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# do_builtins, enabled by command line option -b. See also
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# QAPISchemaGenTypeVisitor.visit_end().
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do_builtins = False
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(input_file, output_dir, do_c, do_h, prefix, opts) = \
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parse_command_line("b", ["builtins"])
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for o, a in opts:
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if o in ("-b", "--builtins"):
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do_builtins = True
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c_comment = '''
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/*
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* deallocation functions for schema-defined QAPI types
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*
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* Copyright IBM, Corp. 2011
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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* Michael Roth <mdroth@linux.vnet.ibm.com>
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*
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* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
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* See the COPYING.LIB file in the top-level directory.
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*
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*/
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'''
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h_comment = '''
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/*
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* schema-defined QAPI types
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*
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* Copyright IBM, Corp. 2011
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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*
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* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
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* See the COPYING.LIB file in the top-level directory.
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*
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*/
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'''
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(fdef, fdecl) = open_output(output_dir, do_c, do_h, prefix,
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'qapi-types.c', 'qapi-types.h',
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c_comment, h_comment)
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fdef.write(mcgen('''
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#include "qemu/osdep.h"
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#include "qapi/dealloc-visitor.h"
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#include "%(prefix)sqapi-types.h"
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#include "%(prefix)sqapi-visit.h"
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''',
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prefix=prefix))
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# To avoid circular headers, use only typedefs.h here, not qobject.h
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fdecl.write(mcgen('''
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#include "qemu/typedefs.h"
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'''))
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schema = QAPISchema(input_file)
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gen = QAPISchemaGenTypeVisitor()
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schema.visit(gen)
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fdef.write(gen.defn)
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fdecl.write(gen.decl)
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close_output(fdef, fdecl)
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