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7ce106a96f
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>
312 lines
8.3 KiB
Python
312 lines
8.3 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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# Ugly special case for simple union TODO get rid of it
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simple_union_type = var.simple_union_type()
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if simple_union_type:
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typ = simple_union_type.c_type()
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else:
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typ = var.type.c_unboxed_type()
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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=typ,
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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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