Sometimes, the behaviour of QEMU changes without a change in the QMP syntax (usually by allowing values or operations that previously resulted in an error). QMP clients may still need to know whether they can rely on the changed behavior. Let's add feature flags to the QAPI schema language, so that we can make such changes visible with schema introspection. An example for a schema definition using feature flags looks like this: { 'struct': 'TestType', 'data': { 'number': 'int' }, 'features': [ 'allow-negative-numbers' ] } Introspection information then looks like this: { "name": "TestType", "meta-type": "object", "members": [ { "name": "number", "type": "int" } ], "features": [ "allow-negative-numbers" ] } This patch implements feature flags only for struct types. We'll implement them more widely as needed. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Message-Id: <20190606153803.5278-2-armbru@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
228 lines
7.9 KiB
Python
228 lines
7.9 KiB
Python
"""
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QAPI introspection generator
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Copyright (C) 2015-2018 Red Hat, Inc.
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Authors:
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Markus Armbruster <armbru@redhat.com>
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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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"""
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from qapi.common import *
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def to_qlit(obj, level=0, suppress_first_indent=False):
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def indent(level):
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return level * 4 * ' '
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if isinstance(obj, tuple):
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ifobj, extra = obj
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ifcond = extra.get('if')
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comment = extra.get('comment')
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ret = ''
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if comment:
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ret += indent(level) + '/* %s */\n' % comment
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if ifcond:
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ret += gen_if(ifcond)
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ret += to_qlit(ifobj, level)
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if ifcond:
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ret += '\n' + gen_endif(ifcond)
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return ret
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ret = ''
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if not suppress_first_indent:
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ret += indent(level)
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if obj is None:
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ret += 'QLIT_QNULL'
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elif isinstance(obj, str):
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ret += 'QLIT_QSTR(' + to_c_string(obj) + ')'
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elif isinstance(obj, list):
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elts = [to_qlit(elt, level + 1).strip('\n')
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for elt in obj]
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elts.append(indent(level + 1) + "{}")
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ret += 'QLIT_QLIST(((QLitObject[]) {\n'
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ret += '\n'.join(elts) + '\n'
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ret += indent(level) + '}))'
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elif isinstance(obj, dict):
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elts = []
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for key, value in sorted(obj.items()):
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elts.append(indent(level + 1) + '{ %s, %s }' %
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(to_c_string(key), to_qlit(value, level + 1, True)))
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elts.append(indent(level + 1) + '{}')
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ret += 'QLIT_QDICT(((QLitDictEntry[]) {\n'
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ret += ',\n'.join(elts) + '\n'
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ret += indent(level) + '}))'
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elif isinstance(obj, bool):
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ret += 'QLIT_QBOOL(%s)' % ('true' if obj else 'false')
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else:
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assert False # not implemented
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if level > 0:
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ret += ','
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return ret
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def to_c_string(string):
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return '"' + string.replace('\\', r'\\').replace('"', r'\"') + '"'
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class QAPISchemaGenIntrospectVisitor(QAPISchemaMonolithicCVisitor):
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def __init__(self, prefix, unmask):
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QAPISchemaMonolithicCVisitor.__init__(
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self, prefix, 'qapi-introspect',
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' * QAPI/QMP schema introspection', __doc__)
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self._unmask = unmask
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self._schema = None
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self._qlits = []
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self._used_types = []
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self._name_map = {}
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self._genc.add(mcgen('''
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#include "qemu/osdep.h"
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#include "%(prefix)sqapi-introspect.h"
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''',
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prefix=prefix))
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def visit_begin(self, schema):
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self._schema = schema
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def visit_end(self):
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# visit the types that are actually used
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for typ in self._used_types:
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typ.visit(self)
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# generate C
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name = c_name(self._prefix, protect=False) + 'qmp_schema_qlit'
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self._genh.add(mcgen('''
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#include "qapi/qmp/qlit.h"
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extern const QLitObject %(c_name)s;
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''',
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c_name=c_name(name)))
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self._genc.add(mcgen('''
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const QLitObject %(c_name)s = %(c_string)s;
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''',
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c_name=c_name(name),
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c_string=to_qlit(self._qlits)))
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self._schema = None
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self._qlits = []
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self._used_types = []
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self._name_map = {}
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def visit_needed(self, entity):
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# Ignore types on first pass; visit_end() will pick up used types
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return not isinstance(entity, QAPISchemaType)
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def _name(self, name):
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if self._unmask:
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return name
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if name not in self._name_map:
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self._name_map[name] = '%d' % len(self._name_map)
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return self._name_map[name]
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def _use_type(self, typ):
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# Map the various integer types to plain int
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if typ.json_type() == 'int':
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typ = self._schema.lookup_type('int')
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elif (isinstance(typ, QAPISchemaArrayType) and
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typ.element_type.json_type() == 'int'):
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typ = self._schema.lookup_type('intList')
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# Add type to work queue if new
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if typ not in self._used_types:
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self._used_types.append(typ)
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# Clients should examine commands and events, not types. Hide
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# type names as integers to reduce the temptation. Also, it
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# saves a few characters on the wire.
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if isinstance(typ, QAPISchemaBuiltinType):
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return typ.name
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if isinstance(typ, QAPISchemaArrayType):
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return '[' + self._use_type(typ.element_type) + ']'
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return self._name(typ.name)
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def _gen_qlit(self, name, mtype, obj, ifcond):
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extra = {}
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if mtype not in ('command', 'event', 'builtin', 'array'):
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if not self._unmask:
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# Output a comment to make it easy to map masked names
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# back to the source when reading the generated output.
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extra['comment'] = '"%s" = %s' % (self._name(name), name)
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name = self._name(name)
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obj['name'] = name
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obj['meta-type'] = mtype
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if ifcond:
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extra['if'] = ifcond
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if extra:
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self._qlits.append((obj, extra))
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else:
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self._qlits.append(obj)
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def _gen_member(self, member):
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ret = {'name': member.name, 'type': self._use_type(member.type)}
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if member.optional:
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ret['default'] = None
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if member.ifcond:
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ret = (ret, {'if': member.ifcond})
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return ret
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def _gen_variants(self, tag_name, variants):
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return {'tag': tag_name,
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'variants': [self._gen_variant(v) for v in variants]}
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def _gen_variant(self, variant):
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return ({'case': variant.name, 'type': self._use_type(variant.type)},
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{'if': variant.ifcond})
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def visit_builtin_type(self, name, info, json_type):
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self._gen_qlit(name, 'builtin', {'json-type': json_type}, [])
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def visit_enum_type(self, name, info, ifcond, members, prefix):
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self._gen_qlit(name, 'enum',
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{'values':
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[(m.name, {'if': m.ifcond}) for m in members]},
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ifcond)
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def visit_array_type(self, name, info, ifcond, element_type):
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element = self._use_type(element_type)
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self._gen_qlit('[' + element + ']', 'array', {'element-type': element},
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ifcond)
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def visit_object_type_flat(self, name, info, ifcond, members, variants,
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features):
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obj = {'members': [self._gen_member(m) for m in members]}
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if variants:
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obj.update(self._gen_variants(variants.tag_member.name,
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variants.variants))
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if features:
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obj['features'] = [(f.name, {'if': f.ifcond}) for f in features]
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self._gen_qlit(name, 'object', obj, ifcond)
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def visit_alternate_type(self, name, info, ifcond, variants):
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self._gen_qlit(name, 'alternate',
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{'members': [
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({'type': self._use_type(m.type)}, {'if': m.ifcond})
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for m in variants.variants]}, ifcond)
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def visit_command(self, name, info, ifcond, arg_type, ret_type, gen,
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success_response, boxed, allow_oob, allow_preconfig):
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arg_type = arg_type or self._schema.the_empty_object_type
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ret_type = ret_type or self._schema.the_empty_object_type
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obj = {'arg-type': self._use_type(arg_type),
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'ret-type': self._use_type(ret_type)}
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if allow_oob:
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obj['allow-oob'] = allow_oob
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self._gen_qlit(name, 'command', obj, ifcond)
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def visit_event(self, name, info, ifcond, arg_type, boxed):
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arg_type = arg_type or self._schema.the_empty_object_type
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self._gen_qlit(name, 'event', {'arg-type': self._use_type(arg_type)},
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ifcond)
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def gen_introspect(schema, output_dir, prefix, opt_unmask):
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vis = QAPISchemaGenIntrospectVisitor(prefix, opt_unmask)
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schema.visit(vis)
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vis.write(output_dir)
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