scripts/qapi/introspect.py - qemu - Git at Google

 """
 QAPI introspection generator

 Copyright (C) 2015-2021 Red Hat, Inc.

 Authors:
  Markus Armbruster <armbru@redhat.com>
  John Snow <jsnow@redhat.com>

 This work is licensed under the terms of the GNU GPL, version 2.
 See the COPYING file in the top-level directory.
 """

 from typing import (
     Any,
     Dict,
     Generic,
     List,
     Optional,
     Sequence,
     TypeVar,
     Union,
 )

 from .common import c_name, mcgen
 from .gen import QAPISchemaMonolithicCVisitor
 from .schema import (
     QAPISchema,
     QAPISchemaArrayType,
     QAPISchemaBuiltinType,
     QAPISchemaEntity,
     QAPISchemaEnumMember,
     QAPISchemaFeature,
     QAPISchemaIfCond,
     QAPISchemaObjectType,
     QAPISchemaObjectTypeMember,
     QAPISchemaType,
     QAPISchemaVariant,
     QAPISchemaVariants,
 )
 from .source import QAPISourceInfo


 # This module constructs a tree data structure that is used to
 # generate the introspection information for QEMU. It is shaped
 # like a JSON value.
 #
 # A complexity over JSON is that our values may or may not be annotated.
 #
 # Un-annotated values may be:
 #     Scalar: str, bool, None.
 #     Non-scalar: List, Dict
 # _value = Union[str, bool, None, Dict[str, JSONValue], List[JSONValue]]
 #
 # With optional annotations, the type of all values is:
 # JSONValue = Union[_Value, Annotated[_Value]]
 #
 # Sadly, mypy does not support recursive types; so the _Stub alias is used to
 # mark the imprecision in the type model where we'd otherwise use JSONValue.
 _Stub = Any
 _Scalar = Union[str, bool, None]
 _NonScalar = Union[Dict[str, _Stub], List[_Stub]]
 _Value = Union[_Scalar, _NonScalar]
 JSONValue = Union[_Value, 'Annotated[_Value]']

 # These types are based on structures defined in QEMU's schema, so we
 # lack precise types for them here. Python 3.6 does not offer
 # TypedDict constructs, so they are broadly typed here as simple
 # Python Dicts.
 SchemaInfo = Dict[str, object]
 SchemaInfoEnumMember = Dict[str, object]
 SchemaInfoObject = Dict[str, object]
 SchemaInfoObjectVariant = Dict[str, object]
 SchemaInfoObjectMember = Dict[str, object]
 SchemaInfoCommand = Dict[str, object]


 _ValueT = TypeVar('_ValueT', bound=_Value)


 class Annotated(Generic[_ValueT]):
     """
     Annotated generally contains a SchemaInfo-like type (as a dict),
     But it also used to wrap comments/ifconds around scalar leaf values,
     for the benefit of features and enums.
     """
     # TODO: Remove after Python 3.7 adds @dataclass:
     # pylint: disable=too-few-public-methods
     def __init__(self, value: _ValueT, ifcond: QAPISchemaIfCond,
                  comment: Optional[str] = None):
         self.value = value
         self.comment: Optional[str] = comment
         self.ifcond = ifcond


 def _tree_to_qlit(obj: JSONValue,
                   level: int = 0,
                   dict_value: bool = False) -> str:
     """
     Convert the type tree into a QLIT C string, recursively.

     :param obj: The value to convert.
                 This value may not be Annotated when dict_value is True.
     :param level: The indentation level for this particular value.
     :param dict_value: True when the value being processed belongs to a
                        dict key; which suppresses the output indent.
     """

     def indent(level: int) -> str:
         return level * 4 * ' '

     if isinstance(obj, Annotated):
         # NB: _tree_to_qlit is called recursively on the values of a
         # key:value pair; those values can't be decorated with
         # comments or conditionals.
         msg = "dict values cannot have attached comments or if-conditionals."
         assert not dict_value, msg

         ret = ''
         if obj.comment:
             ret += indent(level) + f"/* {obj.comment} */\n"
         if obj.ifcond.is_present():
             ret += obj.ifcond.gen_if()
         ret += _tree_to_qlit(obj.value, level)
         if obj.ifcond.is_present():
             ret += '\n' + obj.ifcond.gen_endif()
         return ret

     ret = ''
     if not dict_value:
         ret += indent(level)

     # Scalars:
     if obj is None:
         ret += 'QLIT_QNULL'
     elif isinstance(obj, str):
         ret += f"QLIT_QSTR({to_c_string(obj)})"
     elif isinstance(obj, bool):
         ret += f"QLIT_QBOOL({str(obj).lower()})"

     # Non-scalars:
     elif isinstance(obj, list):
         ret += 'QLIT_QLIST(((QLitObject[]) {\n'
         for value in obj:
             ret += _tree_to_qlit(value, level + 1).strip('\n') + '\n'
         ret += indent(level + 1) + '{}\n'
         ret += indent(level) + '}))'
     elif isinstance(obj, dict):
         ret += 'QLIT_QDICT(((QLitDictEntry[]) {\n'
         for key, value in sorted(obj.items()):
             ret += indent(level + 1) + "{{ {:s}, {:s} }},\n".format(
                 to_c_string(key),
                 _tree_to_qlit(value, level + 1, dict_value=True)
             )
         ret += indent(level + 1) + '{}\n'
         ret += indent(level) + '}))'
     else:
         raise NotImplementedError(
             f"type '{type(obj).__name__}' not implemented"
         )

     if level > 0:
         ret += ','
     return ret


 def to_c_string(string: str) -> str:
     return '"' + string.replace('\\', r'\\').replace('"', r'\"') + '"'


 class QAPISchemaGenIntrospectVisitor(QAPISchemaMonolithicCVisitor):

     def __init__(self, prefix: str, unmask: bool):
         super().__init__(
             prefix, 'qapi-introspect',
             ' * QAPI/QMP schema introspection', __doc__)
         self._unmask = unmask
         self._schema: Optional[QAPISchema] = None
         self._trees: List[Annotated[SchemaInfo]] = []
         self._used_types: List[QAPISchemaType] = []
         self._name_map: Dict[str, str] = {}
         self._genc.add(mcgen('''
 #include "qemu/osdep.h"
 #include "%(prefix)sqapi-introspect.h"

 ''',
                              prefix=prefix))

     def visit_begin(self, schema: QAPISchema) -> None:
         self._schema = schema

     def visit_end(self) -> None:
         # visit the types that are actually used
         for typ in self._used_types:
             typ.visit(self)
         # generate C
         name = c_name(self._prefix, protect=False) + 'qmp_schema_qlit'
         self._genh.add(mcgen('''
 #include "qapi/qmp/qlit.h"

 extern const QLitObject %(c_name)s;
 ''',
                              c_name=c_name(name)))
         self._genc.add(mcgen('''
 const QLitObject %(c_name)s = %(c_string)s;
 ''',
                              c_name=c_name(name),
                              c_string=_tree_to_qlit(self._trees)))
         self._schema = None
         self._trees = []
         self._used_types = []
         self._name_map = {}

     def visit_needed(self, entity: QAPISchemaEntity) -> bool:
         # Ignore types on first pass; visit_end() will pick up used types
         return not isinstance(entity, QAPISchemaType)

     def _name(self, name: str) -> str:
         if self._unmask:
             return name
         if name not in self._name_map:
             self._name_map[name] = '%d' % len(self._name_map)
         return self._name_map[name]

     def _use_type(self, typ: QAPISchemaType) -> str:
         assert self._schema is not None

         # Map the various integer types to plain int
         if typ.json_type() == 'int':
             typ = self._schema.lookup_type('int')
         elif (isinstance(typ, QAPISchemaArrayType) and
               typ.element_type.json_type() == 'int'):
             typ = self._schema.lookup_type('intList')
         # Add type to work queue if new
         if typ not in self._used_types:
             self._used_types.append(typ)
         # Clients should examine commands and events, not types.  Hide
         # type names as integers to reduce the temptation.  Also, it
         # saves a few characters on the wire.
         if isinstance(typ, QAPISchemaBuiltinType):
             return typ.name
         if isinstance(typ, QAPISchemaArrayType):
             return '[' + self._use_type(typ.element_type) + ']'
         return self._name(typ.name)

     @staticmethod
     def _gen_features(features: Sequence[QAPISchemaFeature]
                       ) -> List[Annotated[str]]:
         return [Annotated(f.name, f.ifcond) for f in features]

     def _gen_tree(self, name: str, mtype: str, obj: Dict[str, object],
                   ifcond: QAPISchemaIfCond = QAPISchemaIfCond(),
                   features: Sequence[QAPISchemaFeature] = ()) -> None:
         """
         Build and append a SchemaInfo object to self._trees.

         :param name: The SchemaInfo's name.
         :param mtype: The SchemaInfo's meta-type.
         :param obj: Additional SchemaInfo members, as appropriate for
                     the meta-type.
         :param ifcond: Conditionals to apply to the SchemaInfo.
         :param features: The SchemaInfo's features.
                          Will be omitted from the output if empty.
         """
         comment: Optional[str] = None
         if mtype not in ('command', 'event', 'builtin', 'array'):
             if not self._unmask:
                 # Output a comment to make it easy to map masked names
                 # back to the source when reading the generated output.
                 comment = f'"{self._name(name)}" = {name}'
             name = self._name(name)
         obj['name'] = name
         obj['meta-type'] = mtype
         if features:
             obj['features'] = self._gen_features(features)
         self._trees.append(Annotated(obj, ifcond, comment))

     def _gen_enum_member(self, member: QAPISchemaEnumMember
                          ) -> Annotated[SchemaInfoEnumMember]:
         obj: SchemaInfoEnumMember = {
             'name': member.name,
         }
         if member.features:
             obj['features'] = self._gen_features(member.features)
         return Annotated(obj, member.ifcond)

     def _gen_object_member(self, member: QAPISchemaObjectTypeMember
                            ) -> Annotated[SchemaInfoObjectMember]:
         obj: SchemaInfoObjectMember = {
             'name': member.name,
             'type': self._use_type(member.type)
         }
         if member.optional:
             obj['default'] = None
         if member.features:
             obj['features'] = self._gen_features(member.features)
         return Annotated(obj, member.ifcond)

     def _gen_variant(self, variant: QAPISchemaVariant
                      ) -> Annotated[SchemaInfoObjectVariant]:
         obj: SchemaInfoObjectVariant = {
             'case': variant.name,
             'type': self._use_type(variant.type)
         }
         return Annotated(obj, variant.ifcond)

     def visit_builtin_type(self, name: str, info: Optional[QAPISourceInfo],
                            json_type: str) -> None:
         self._gen_tree(name, 'builtin', {'json-type': json_type})

     def visit_enum_type(self, name: str, info: Optional[QAPISourceInfo],
                         ifcond: QAPISchemaIfCond,
                         features: List[QAPISchemaFeature],
                         members: List[QAPISchemaEnumMember],
                         prefix: Optional[str]) -> None:
         self._gen_tree(
             name, 'enum',
             {'members': [self._gen_enum_member(m) for m in members],
              'values': [Annotated(m.name, m.ifcond) for m in members]},
             ifcond, features
         )

     def visit_array_type(self, name: str, info: Optional[QAPISourceInfo],
                          ifcond: QAPISchemaIfCond,
                          element_type: QAPISchemaType) -> None:
         element = self._use_type(element_type)
         self._gen_tree('[' + element + ']', 'array', {'element-type': element},
                        ifcond)

     def visit_object_type_flat(self, name: str, info: Optional[QAPISourceInfo],
                                ifcond: QAPISchemaIfCond,
                                features: List[QAPISchemaFeature],
                                members: List[QAPISchemaObjectTypeMember],
                                variants: Optional[QAPISchemaVariants]) -> None:
         obj: SchemaInfoObject = {
             'members': [self._gen_object_member(m) for m in members]
         }
         if variants:
             obj['tag'] = variants.tag_member.name
             obj['variants'] = [self._gen_variant(v) for v in variants.variants]
         self._gen_tree(name, 'object', obj, ifcond, features)

     def visit_alternate_type(self, name: str, info: Optional[QAPISourceInfo],
                              ifcond: QAPISchemaIfCond,
                              features: List[QAPISchemaFeature],
                              variants: QAPISchemaVariants) -> None:
         self._gen_tree(
             name, 'alternate',
             {'members': [Annotated({'type': self._use_type(m.type)},
                                    m.ifcond)
                          for m in variants.variants]},
             ifcond, features
         )

     def visit_command(self, name: str, info: Optional[QAPISourceInfo],
                       ifcond: QAPISchemaIfCond,
                       features: List[QAPISchemaFeature],
                       arg_type: Optional[QAPISchemaObjectType],
                       ret_type: Optional[QAPISchemaType], gen: bool,
                       success_response: bool, boxed: bool, allow_oob: bool,
                       allow_preconfig: bool, coroutine: bool) -> None:
         assert self._schema is not None

         arg_type = arg_type or self._schema.the_empty_object_type
         ret_type = ret_type or self._schema.the_empty_object_type
         obj: SchemaInfoCommand = {
             'arg-type': self._use_type(arg_type),
             'ret-type': self._use_type(ret_type)
         }
         if allow_oob:
             obj['allow-oob'] = allow_oob
         self._gen_tree(name, 'command', obj, ifcond, features)

     def visit_event(self, name: str, info: Optional[QAPISourceInfo],
                     ifcond: QAPISchemaIfCond,
                     features: List[QAPISchemaFeature],
                     arg_type: Optional[QAPISchemaObjectType],
                     boxed: bool) -> None:
         assert self._schema is not None

         arg_type = arg_type or self._schema.the_empty_object_type
         self._gen_tree(name, 'event', {'arg-type': self._use_type(arg_type)},
                        ifcond, features)


 def gen_introspect(schema: QAPISchema, output_dir: str, prefix: str,
                    opt_unmask: bool) -> None:
     vis = QAPISchemaGenIntrospectVisitor(prefix, opt_unmask)
     schema.visit(vis)
     vis.write(output_dir)
	"""
	QAPI introspection generator

	Copyright (C) 2015-2021 Red Hat, Inc.

	Authors:
	Markus Armbruster <armbru@redhat.com>
	John Snow <jsnow@redhat.com>

	This work is licensed under the terms of the GNU GPL, version 2.
	See the COPYING file in the top-level directory.
	"""

	from typing import (
	Any,
	Dict,
	Generic,
	List,
	Optional,
	Sequence,
	TypeVar,
	Union,
	)

	from .common import c_name, mcgen
	from .gen import QAPISchemaMonolithicCVisitor
	from .schema import (
	QAPISchema,
	QAPISchemaArrayType,
	QAPISchemaBuiltinType,
	QAPISchemaEntity,
	QAPISchemaEnumMember,
	QAPISchemaFeature,
	QAPISchemaIfCond,
	QAPISchemaObjectType,
	QAPISchemaObjectTypeMember,
	QAPISchemaType,
	QAPISchemaVariant,
	QAPISchemaVariants,
	)
	from .source import QAPISourceInfo


	# This module constructs a tree data structure that is used to
	# generate the introspection information for QEMU. It is shaped
	# like a JSON value.
	#
	# A complexity over JSON is that our values may or may not be annotated.
	#
	# Un-annotated values may be:
	# Scalar: str, bool, None.
	# Non-scalar: List, Dict
	# _value = Union[str, bool, None, Dict[str, JSONValue], List[JSONValue]]
	#
	# With optional annotations, the type of all values is:
	# JSONValue = Union[_Value, Annotated[_Value]]
	#
	# Sadly, mypy does not support recursive types; so the _Stub alias is used to
	# mark the imprecision in the type model where we'd otherwise use JSONValue.
	_Stub = Any
	_Scalar = Union[str, bool, None]
	_NonScalar = Union[Dict[str, _Stub], List[_Stub]]
	_Value = Union[_Scalar, _NonScalar]
	JSONValue = Union[_Value, 'Annotated[_Value]']

	# These types are based on structures defined in QEMU's schema, so we
	# lack precise types for them here. Python 3.6 does not offer
	# TypedDict constructs, so they are broadly typed here as simple
	# Python Dicts.
	SchemaInfo = Dict[str, object]
	SchemaInfoEnumMember = Dict[str, object]
	SchemaInfoObject = Dict[str, object]
	SchemaInfoObjectVariant = Dict[str, object]
	SchemaInfoObjectMember = Dict[str, object]
	SchemaInfoCommand = Dict[str, object]


	_ValueT = TypeVar('_ValueT', bound=_Value)


	class Annotated(Generic[_ValueT]):
	"""
	Annotated generally contains a SchemaInfo-like type (as a dict),
	But it also used to wrap comments/ifconds around scalar leaf values,
	for the benefit of features and enums.
	"""
	# TODO: Remove after Python 3.7 adds @dataclass:
	# pylint: disable=too-few-public-methods
	def __init__(self, value: _ValueT, ifcond: QAPISchemaIfCond,
	comment: Optional[str] = None):
	self.value = value
	self.comment: Optional[str] = comment
	self.ifcond = ifcond


	def _tree_to_qlit(obj: JSONValue,
	level: int = 0,
	dict_value: bool = False) -> str:
	"""
	Convert the type tree into a QLIT C string, recursively.

	:param obj: The value to convert.
	This value may not be Annotated when dict_value is True.
	:param level: The indentation level for this particular value.
	:param dict_value: True when the value being processed belongs to a
	dict key; which suppresses the output indent.
	"""

	def indent(level: int) -> str:
	return level * 4 * ' '

	if isinstance(obj, Annotated):
	# NB: _tree_to_qlit is called recursively on the values of a
	# key:value pair; those values can't be decorated with
	# comments or conditionals.
	msg = "dict values cannot have attached comments or if-conditionals."
	assert not dict_value, msg

	ret = ''
	if obj.comment:
	ret += indent(level) + f"/* {obj.comment} */\n"
	if obj.ifcond.is_present():
	ret += obj.ifcond.gen_if()
	ret += _tree_to_qlit(obj.value, level)
	if obj.ifcond.is_present():
	ret += '\n' + obj.ifcond.gen_endif()
	return ret

	ret = ''
	if not dict_value:
	ret += indent(level)

	# Scalars:
	if obj is None:
	ret += 'QLIT_QNULL'
	elif isinstance(obj, str):
	ret += f"QLIT_QSTR({to_c_string(obj)})"
	elif isinstance(obj, bool):
	ret += f"QLIT_QBOOL({str(obj).lower()})"

	# Non-scalars:
	elif isinstance(obj, list):
	ret += 'QLIT_QLIST(((QLitObject[]) {\n'
	for value in obj:
	ret += _tree_to_qlit(value, level + 1).strip('\n') + '\n'
	ret += indent(level + 1) + '{}\n'
	ret += indent(level) + '}))'
	elif isinstance(obj, dict):
	ret += 'QLIT_QDICT(((QLitDictEntry[]) {\n'
	for key, value in sorted(obj.items()):
	ret += indent(level + 1) + "{{ {:s}, {:s} }},\n".format(
	to_c_string(key),
	_tree_to_qlit(value, level + 1, dict_value=True)
	)
	ret += indent(level + 1) + '{}\n'
	ret += indent(level) + '}))'
	else:
	raise NotImplementedError(
	f"type '{type(obj).__name__}' not implemented"
	)

	if level > 0:
	ret += ','
	return ret


	def to_c_string(string: str) -> str:
	return '"' + string.replace('\\', r'\\').replace('"', r'\"') + '"'


	class QAPISchemaGenIntrospectVisitor(QAPISchemaMonolithicCVisitor):

	def __init__(self, prefix: str, unmask: bool):
	super().__init__(
	prefix, 'qapi-introspect',
	' * QAPI/QMP schema introspection', __doc__)
	self._unmask = unmask
	self._schema: Optional[QAPISchema] = None
	self._trees: List[Annotated[SchemaInfo]] = []
	self._used_types: List[QAPISchemaType] = []
	self._name_map: Dict[str, str] = {}
	self._genc.add(mcgen('''
	#include "qemu/osdep.h"
	#include "%(prefix)sqapi-introspect.h"

	''',
	prefix=prefix))

	def visit_begin(self, schema: QAPISchema) -> None:
	self._schema = schema

	def visit_end(self) -> None:
	# visit the types that are actually used
	for typ in self._used_types:
	typ.visit(self)
	# generate C
	name = c_name(self._prefix, protect=False) + 'qmp_schema_qlit'
	self._genh.add(mcgen('''
	#include "qapi/qmp/qlit.h"

	extern const QLitObject %(c_name)s;
	''',
	c_name=c_name(name)))
	self._genc.add(mcgen('''
	const QLitObject %(c_name)s = %(c_string)s;
	''',
	c_name=c_name(name),
	c_string=_tree_to_qlit(self._trees)))
	self._schema = None
	self._trees = []
	self._used_types = []
	self._name_map = {}

	def visit_needed(self, entity: QAPISchemaEntity) -> bool:
	# Ignore types on first pass; visit_end() will pick up used types
	return not isinstance(entity, QAPISchemaType)

	def _name(self, name: str) -> str:
	if self._unmask:
	return name
	if name not in self._name_map:
	self._name_map[name] = '%d' % len(self._name_map)
	return self._name_map[name]

	def _use_type(self, typ: QAPISchemaType) -> str:
	assert self._schema is not None

	# Map the various integer types to plain int
	if typ.json_type() == 'int':
	typ = self._schema.lookup_type('int')
	elif (isinstance(typ, QAPISchemaArrayType) and
	typ.element_type.json_type() == 'int'):
	typ = self._schema.lookup_type('intList')
	# Add type to work queue if new
	if typ not in self._used_types:
	self._used_types.append(typ)
	# Clients should examine commands and events, not types. Hide
	# type names as integers to reduce the temptation. Also, it
	# saves a few characters on the wire.
	if isinstance(typ, QAPISchemaBuiltinType):
	return typ.name
	if isinstance(typ, QAPISchemaArrayType):
	return '[' + self._use_type(typ.element_type) + ']'
	return self._name(typ.name)

	@staticmethod
	def _gen_features(features: Sequence[QAPISchemaFeature]
	) -> List[Annotated[str]]:
	return [Annotated(f.name, f.ifcond) for f in features]

	def _gen_tree(self, name: str, mtype: str, obj: Dict[str, object],
	ifcond: QAPISchemaIfCond = QAPISchemaIfCond(),
	features: Sequence[QAPISchemaFeature] = ()) -> None:
	"""
	Build and append a SchemaInfo object to self._trees.

	:param name: The SchemaInfo's name.
	:param mtype: The SchemaInfo's meta-type.
	:param obj: Additional SchemaInfo members, as appropriate for
	the meta-type.
	:param ifcond: Conditionals to apply to the SchemaInfo.
	:param features: The SchemaInfo's features.
	Will be omitted from the output if empty.
	"""
	comment: Optional[str] = None
	if mtype not in ('command', 'event', 'builtin', 'array'):
	if not self._unmask:
	# Output a comment to make it easy to map masked names
	# back to the source when reading the generated output.
	comment = f'"{self._name(name)}" = {name}'
	name = self._name(name)
	obj['name'] = name
	obj['meta-type'] = mtype
	if features:
	obj['features'] = self._gen_features(features)
	self._trees.append(Annotated(obj, ifcond, comment))

	def _gen_enum_member(self, member: QAPISchemaEnumMember
	) -> Annotated[SchemaInfoEnumMember]:
	obj: SchemaInfoEnumMember = {
	'name': member.name,
	}
	if member.features:
	obj['features'] = self._gen_features(member.features)
	return Annotated(obj, member.ifcond)

	def _gen_object_member(self, member: QAPISchemaObjectTypeMember
	) -> Annotated[SchemaInfoObjectMember]:
	obj: SchemaInfoObjectMember = {
	'name': member.name,
	'type': self._use_type(member.type)
	}
	if member.optional:
	obj['default'] = None
	if member.features:
	obj['features'] = self._gen_features(member.features)
	return Annotated(obj, member.ifcond)

	def _gen_variant(self, variant: QAPISchemaVariant
	) -> Annotated[SchemaInfoObjectVariant]:
	obj: SchemaInfoObjectVariant = {
	'case': variant.name,
	'type': self._use_type(variant.type)
	}
	return Annotated(obj, variant.ifcond)

	def visit_builtin_type(self, name: str, info: Optional[QAPISourceInfo],
	json_type: str) -> None:
	self._gen_tree(name, 'builtin', {'json-type': json_type})

	def visit_enum_type(self, name: str, info: Optional[QAPISourceInfo],
	ifcond: QAPISchemaIfCond,
	features: List[QAPISchemaFeature],
	members: List[QAPISchemaEnumMember],
	prefix: Optional[str]) -> None:
	self._gen_tree(
	name, 'enum',
	{'members': [self._gen_enum_member(m) for m in members],
	'values': [Annotated(m.name, m.ifcond) for m in members]},
	ifcond, features
	)

	def visit_array_type(self, name: str, info: Optional[QAPISourceInfo],
	ifcond: QAPISchemaIfCond,
	element_type: QAPISchemaType) -> None:
	element = self._use_type(element_type)
	self._gen_tree('[' + element + ']', 'array', {'element-type': element},
	ifcond)

	def visit_object_type_flat(self, name: str, info: Optional[QAPISourceInfo],
	ifcond: QAPISchemaIfCond,
	features: List[QAPISchemaFeature],
	members: List[QAPISchemaObjectTypeMember],
	variants: Optional[QAPISchemaVariants]) -> None:
	obj: SchemaInfoObject = {
	'members': [self._gen_object_member(m) for m in members]
	}
	if variants:
	obj['tag'] = variants.tag_member.name
	obj['variants'] = [self._gen_variant(v) for v in variants.variants]
	self._gen_tree(name, 'object', obj, ifcond, features)

	def visit_alternate_type(self, name: str, info: Optional[QAPISourceInfo],
	ifcond: QAPISchemaIfCond,
	features: List[QAPISchemaFeature],
	variants: QAPISchemaVariants) -> None:
	self._gen_tree(
	name, 'alternate',
	{'members': [Annotated({'type': self._use_type(m.type)},
	m.ifcond)
	for m in variants.variants]},
	ifcond, features
	)

	def visit_command(self, name: str, info: Optional[QAPISourceInfo],
	ifcond: QAPISchemaIfCond,
	features: List[QAPISchemaFeature],
	arg_type: Optional[QAPISchemaObjectType],
	ret_type: Optional[QAPISchemaType], gen: bool,
	success_response: bool, boxed: bool, allow_oob: bool,
	allow_preconfig: bool, coroutine: bool) -> None:
	assert self._schema is not None

	arg_type = arg_type or self._schema.the_empty_object_type
	ret_type = ret_type or self._schema.the_empty_object_type
	obj: SchemaInfoCommand = {
	'arg-type': self._use_type(arg_type),
	'ret-type': self._use_type(ret_type)
	}
	if allow_oob:
	obj['allow-oob'] = allow_oob
	self._gen_tree(name, 'command', obj, ifcond, features)

	def visit_event(self, name: str, info: Optional[QAPISourceInfo],
	ifcond: QAPISchemaIfCond,
	features: List[QAPISchemaFeature],
	arg_type: Optional[QAPISchemaObjectType],
	boxed: bool) -> None:
	assert self._schema is not None

	arg_type = arg_type or self._schema.the_empty_object_type
	self._gen_tree(name, 'event', {'arg-type': self._use_type(arg_type)},
	ifcond, features)


	def gen_introspect(schema: QAPISchema, output_dir: str, prefix: str,
	opt_unmask: bool) -> None:
	vis = QAPISchemaGenIntrospectVisitor(prefix, opt_unmask)
	schema.visit(vis)
	vis.write(output_dir)