scripts/qapi/schema.py

   1 # -*- coding: utf-8 -*-
   2 #
   3 # QAPI schema internal representation
   4 #
   5 # Copyright (c) 2015-2019 Red Hat Inc.
   6 #
   7 # Authors:
   8 #  Markus Armbruster <armbru@redhat.com>
   9 #  Eric Blake <eblake@redhat.com>
  10 #  Marc-André Lureau <marcandre.lureau@redhat.com>
  11 #
  12 # This work is licensed under the terms of the GNU GPL, version 2.
  13 # See the COPYING file in the top-level directory.
  14
  15 # pylint: disable=too-many-lines
  16
  17 # TODO catching name collisions in generated code would be nice
  18
  19 from __future__ import annotations
  20
  21 from abc import ABC, abstractmethod
  22 from collections import OrderedDict
  23 import os
  24 import re
  25 from typing import (
  26     Any,
  27     Callable,
  28     Dict,
  29     List,
  30     Optional,
  31     Union,
  32     cast,
  33 )
  34
  35 from .common import (
  36     POINTER_SUFFIX,
  37     c_name,
  38     cgen_ifcond,
  39     docgen_ifcond,
  40     gen_endif,
  41     gen_if,
  42 )
  43 from .error import QAPIError, QAPISemError, QAPISourceError
  44 from .expr import check_exprs
  45 from .parser import QAPIDoc, QAPIExpression, QAPISchemaParser
  46 from .source import QAPISourceInfo
  47
  48
  49 class QAPISchemaIfCond:
  50     def __init__(
  51         self,
  52         ifcond: Optional[Union[str, Dict[str, object]]] = None,
  53     ) -> None:
  54         self.ifcond = ifcond
  55
  56     def _cgen(self) -> str:
  57         return cgen_ifcond(self.ifcond)
  58
  59     def gen_if(self) -> str:
  60         return gen_if(self._cgen())
  61
  62     def gen_endif(self) -> str:
  63         return gen_endif(self._cgen())
  64
  65     def docgen(self) -> str:
  66         return docgen_ifcond(self.ifcond)
  67
  68     def is_present(self) -> bool:
  69         return bool(self.ifcond)
  70
  71
  72 class QAPISchemaEntity:
  73     """
  74     A schema entity.
  75
  76     This is either a directive, such as include, or a definition.
  77     The latter uses sub-class `QAPISchemaDefinition`.
  78     """
  79     def __init__(self, info: Optional[QAPISourceInfo]):
  80         self._module: Optional[QAPISchemaModule] = None
  81         # For explicitly defined entities, info points to the (explicit)
  82         # definition.  For builtins (and their arrays), info is None.
  83         # For implicitly defined entities, info points to a place that
  84         # triggered the implicit definition (there may be more than one
  85         # such place).
  86         self.info = info
  87         self._checked = False
  88
  89     def __repr__(self) -> str:
  90         return "<%s at 0x%x>" % (type(self).__name__, id(self))
  91
  92     def check(self, schema: QAPISchema) -> None:
  93         # pylint: disable=unused-argument
  94         self._checked = True
  95
  96     def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
  97         pass
  98
  99     def _set_module(
 100         self, schema: QAPISchema, info: Optional[QAPISourceInfo]
 101     ) -> None:
 102         assert self._checked
 103         fname = info.fname if info else QAPISchemaModule.BUILTIN_MODULE_NAME
 104         self._module = schema.module_by_fname(fname)
 105         self._module.add_entity(self)
 106
 107     def set_module(self, schema: QAPISchema) -> None:
 108         self._set_module(schema, self.info)
 109
 110     def visit(self, visitor: QAPISchemaVisitor) -> None:
 111         # pylint: disable=unused-argument
 112         assert self._checked
 113
 114
 115 class QAPISchemaDefinition(QAPISchemaEntity):
 116     meta: str
 117
 118     def __init__(
 119         self,
 120         name: str,
 121         info: Optional[QAPISourceInfo],
 122         doc: Optional[QAPIDoc],
 123         ifcond: Optional[QAPISchemaIfCond] = None,
 124         features: Optional[List[QAPISchemaFeature]] = None,
 125     ):
 126         super().__init__(info)
 127         for f in features or []:
 128             f.set_defined_in(name)
 129         self.name = name
 130         self.doc = doc
 131         self._ifcond = ifcond or QAPISchemaIfCond()
 132         self.features = features or []
 133
 134     def __repr__(self) -> str:
 135         return "<%s:%s at 0x%x>" % (type(self).__name__, self.name,
 136                                     id(self))
 137
 138     def c_name(self) -> str:
 139         return c_name(self.name)
 140
 141     def check(self, schema: QAPISchema) -> None:
 142         assert not self._checked
 143         super().check(schema)
 144         seen: Dict[str, QAPISchemaMember] = {}
 145         for f in self.features:
 146             f.check_clash(self.info, seen)
 147
 148     def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
 149         super().connect_doc(doc)
 150         doc = doc or self.doc
 151         if doc:
 152             for f in self.features:
 153                 doc.connect_feature(f)
 154
 155     @property
 156     def ifcond(self) -> QAPISchemaIfCond:
 157         assert self._checked
 158         return self._ifcond
 159
 160     def is_implicit(self) -> bool:
 161         return not self.info
 162
 163     def describe(self) -> str:
 164         return "%s '%s'" % (self.meta, self.name)
 165
 166
 167 class QAPISchemaVisitor:
 168     def visit_begin(self, schema: QAPISchema) -> None:
 169         pass
 170
 171     def visit_end(self) -> None:
 172         pass
 173
 174     def visit_module(self, name: str) -> None:
 175         pass
 176
 177     def visit_needed(self, entity: QAPISchemaEntity) -> bool:
 178         # pylint: disable=unused-argument
 179         # Default to visiting everything
 180         return True
 181
 182     def visit_include(self, name: str, info: Optional[QAPISourceInfo]) -> None:
 183         pass
 184
 185     def visit_builtin_type(
 186         self, name: str, info: Optional[QAPISourceInfo], json_type: str
 187     ) -> None:
 188         pass
 189
 190     def visit_enum_type(
 191         self,
 192         name: str,
 193         info: Optional[QAPISourceInfo],
 194         ifcond: QAPISchemaIfCond,
 195         features: List[QAPISchemaFeature],
 196         members: List[QAPISchemaEnumMember],
 197         prefix: Optional[str],
 198     ) -> None:
 199         pass
 200
 201     def visit_array_type(
 202         self,
 203         name: str,
 204         info: Optional[QAPISourceInfo],
 205         ifcond: QAPISchemaIfCond,
 206         element_type: QAPISchemaType,
 207     ) -> None:
 208         pass
 209
 210     def visit_object_type(
 211         self,
 212         name: str,
 213         info: Optional[QAPISourceInfo],
 214         ifcond: QAPISchemaIfCond,
 215         features: List[QAPISchemaFeature],
 216         base: Optional[QAPISchemaObjectType],
 217         members: List[QAPISchemaObjectTypeMember],
 218         branches: Optional[QAPISchemaBranches],
 219     ) -> None:
 220         pass
 221
 222     def visit_object_type_flat(
 223         self,
 224         name: str,
 225         info: Optional[QAPISourceInfo],
 226         ifcond: QAPISchemaIfCond,
 227         features: List[QAPISchemaFeature],
 228         members: List[QAPISchemaObjectTypeMember],
 229         branches: Optional[QAPISchemaBranches],
 230     ) -> None:
 231         pass
 232
 233     def visit_alternate_type(
 234         self,
 235         name: str,
 236         info: Optional[QAPISourceInfo],
 237         ifcond: QAPISchemaIfCond,
 238         features: List[QAPISchemaFeature],
 239         alternatives: QAPISchemaAlternatives,
 240     ) -> None:
 241         pass
 242
 243     def visit_command(
 244         self,
 245         name: str,
 246         info: Optional[QAPISourceInfo],
 247         ifcond: QAPISchemaIfCond,
 248         features: List[QAPISchemaFeature],
 249         arg_type: Optional[QAPISchemaObjectType],
 250         ret_type: Optional[QAPISchemaType],
 251         gen: bool,
 252         success_response: bool,
 253         boxed: bool,
 254         allow_oob: bool,
 255         allow_preconfig: bool,
 256         coroutine: bool,
 257     ) -> None:
 258         pass
 259
 260     def visit_event(
 261         self,
 262         name: str,
 263         info: Optional[QAPISourceInfo],
 264         ifcond: QAPISchemaIfCond,
 265         features: List[QAPISchemaFeature],
 266         arg_type: Optional[QAPISchemaObjectType],
 267         boxed: bool,
 268     ) -> None:
 269         pass
 270
 271
 272 class QAPISchemaModule:
 273
 274     BUILTIN_MODULE_NAME = './builtin'
 275
 276     def __init__(self, name: str):
 277         self.name = name
 278         self._entity_list: List[QAPISchemaEntity] = []
 279
 280     @staticmethod
 281     def is_system_module(name: str) -> bool:
 282         """
 283         System modules are internally defined modules.
 284
 285         Their names start with the "./" prefix.
 286         """
 287         return name.startswith('./')
 288
 289     @classmethod
 290     def is_user_module(cls, name: str) -> bool:
 291         """
 292         User modules are those defined by the user in qapi JSON files.
 293
 294         They do not start with the "./" prefix.
 295         """
 296         return not cls.is_system_module(name)
 297
 298     @classmethod
 299     def is_builtin_module(cls, name: str) -> bool:
 300         """
 301         The built-in module is a single System module for the built-in types.
 302
 303         It is always "./builtin".
 304         """
 305         return name == cls.BUILTIN_MODULE_NAME
 306
 307     def add_entity(self, ent: QAPISchemaEntity) -> None:
 308         self._entity_list.append(ent)
 309
 310     def visit(self, visitor: QAPISchemaVisitor) -> None:
 311         visitor.visit_module(self.name)
 312         for entity in self._entity_list:
 313             if visitor.visit_needed(entity):
 314                 entity.visit(visitor)
 315
 316
 317 class QAPISchemaInclude(QAPISchemaEntity):
 318     def __init__(self, sub_module: QAPISchemaModule, info: QAPISourceInfo):
 319         super().__init__(info)
 320         self._sub_module = sub_module
 321
 322     def visit(self, visitor: QAPISchemaVisitor) -> None:
 323         super().visit(visitor)
 324         visitor.visit_include(self._sub_module.name, self.info)
 325
 326
 327 class QAPISchemaType(QAPISchemaDefinition, ABC):
 328     # Return the C type for common use.
 329     # For the types we commonly box, this is a pointer type.
 330     @abstractmethod
 331     def c_type(self) -> str:
 332         pass
 333
 334     # Return the C type to be used in a parameter list.
 335     def c_param_type(self) -> str:
 336         return self.c_type()
 337
 338     # Return the C type to be used where we suppress boxing.
 339     def c_unboxed_type(self) -> str:
 340         return self.c_type()
 341
 342     @abstractmethod
 343     def json_type(self) -> str:
 344         pass
 345
 346     def alternate_qtype(self) -> Optional[str]:
 347         json2qtype = {
 348             'null':    'QTYPE_QNULL',
 349             'string':  'QTYPE_QSTRING',
 350             'number':  'QTYPE_QNUM',
 351             'int':     'QTYPE_QNUM',
 352             'boolean': 'QTYPE_QBOOL',
 353             'array':   'QTYPE_QLIST',
 354             'object':  'QTYPE_QDICT'
 355         }
 356         return json2qtype.get(self.json_type())
 357
 358     def doc_type(self) -> Optional[str]:
 359         if self.is_implicit():
 360             return None
 361         return self.name
 362
 363     def need_has_if_optional(self) -> bool:
 364         # When FOO is a pointer, has_FOO == !!FOO, i.e. has_FOO is redundant.
 365         # Except for arrays; see QAPISchemaArrayType.need_has_if_optional().
 366         return not self.c_type().endswith(POINTER_SUFFIX)
 367
 368     def check(self, schema: QAPISchema) -> None:
 369         super().check(schema)
 370         for feat in self.features:
 371             if feat.is_special():
 372                 raise QAPISemError(
 373                     self.info,
 374                     f"feature '{feat.name}' is not supported for types")
 375
 376     def describe(self) -> str:
 377         return "%s type '%s'" % (self.meta, self.name)
 378
 379
 380 class QAPISchemaBuiltinType(QAPISchemaType):
 381     meta = 'built-in'
 382
 383     def __init__(self, name: str, json_type: str, c_type: str):
 384         super().__init__(name, None, None)
 385         assert json_type in ('string', 'number', 'int', 'boolean', 'null',
 386                              'value')
 387         self._json_type_name = json_type
 388         self._c_type_name = c_type
 389
 390     def c_name(self) -> str:
 391         return self.name
 392
 393     def c_type(self) -> str:
 394         return self._c_type_name
 395
 396     def c_param_type(self) -> str:
 397         if self.name == 'str':
 398             return 'const ' + self._c_type_name
 399         return self._c_type_name
 400
 401     def json_type(self) -> str:
 402         return self._json_type_name
 403
 404     def doc_type(self) -> str:
 405         return self.json_type()
 406
 407     def visit(self, visitor: QAPISchemaVisitor) -> None:
 408         super().visit(visitor)
 409         visitor.visit_builtin_type(self.name, self.info, self.json_type())
 410
 411
 412 class QAPISchemaEnumType(QAPISchemaType):
 413     meta = 'enum'
 414
 415     def __init__(
 416         self,
 417         name: str,
 418         info: Optional[QAPISourceInfo],
 419         doc: Optional[QAPIDoc],
 420         ifcond: Optional[QAPISchemaIfCond],
 421         features: Optional[List[QAPISchemaFeature]],
 422         members: List[QAPISchemaEnumMember],
 423         prefix: Optional[str],
 424     ):
 425         super().__init__(name, info, doc, ifcond, features)
 426         for m in members:
 427             m.set_defined_in(name)
 428         self.members = members
 429         self.prefix = prefix
 430
 431     def check(self, schema: QAPISchema) -> None:
 432         super().check(schema)
 433         seen: Dict[str, QAPISchemaMember] = {}
 434         for m in self.members:
 435             m.check_clash(self.info, seen)
 436
 437     def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
 438         super().connect_doc(doc)
 439         doc = doc or self.doc
 440         for m in self.members:
 441             m.connect_doc(doc)
 442
 443     def is_implicit(self) -> bool:
 444         # See QAPISchema._def_predefineds()
 445         return self.name == 'QType'
 446
 447     def c_type(self) -> str:
 448         return c_name(self.name)
 449
 450     def member_names(self) -> List[str]:
 451         return [m.name for m in self.members]
 452
 453     def json_type(self) -> str:
 454         return 'string'
 455
 456     def visit(self, visitor: QAPISchemaVisitor) -> None:
 457         super().visit(visitor)
 458         visitor.visit_enum_type(
 459             self.name, self.info, self.ifcond, self.features,
 460             self.members, self.prefix)
 461
 462
 463 class QAPISchemaArrayType(QAPISchemaType):
 464     meta = 'array'
 465
 466     def __init__(
 467         self, name: str, info: Optional[QAPISourceInfo], element_type: str
 468     ):
 469         super().__init__(name, info, None)
 470         self._element_type_name = element_type
 471         self.element_type: QAPISchemaType
 472
 473     def need_has_if_optional(self) -> bool:
 474         # When FOO is an array, we still need has_FOO to distinguish
 475         # absent (!has_FOO) from present and empty (has_FOO && !FOO).
 476         return True
 477
 478     def check(self, schema: QAPISchema) -> None:
 479         super().check(schema)
 480         self.element_type = schema.resolve_type(
 481             self._element_type_name, self.info,
 482             self.info.defn_meta if self.info else None)
 483         assert not isinstance(self.element_type, QAPISchemaArrayType)
 484
 485     def set_module(self, schema: QAPISchema) -> None:
 486         self._set_module(schema, self.element_type.info)
 487
 488     @property
 489     def ifcond(self) -> QAPISchemaIfCond:
 490         assert self._checked
 491         return self.element_type.ifcond
 492
 493     def is_implicit(self) -> bool:
 494         return True
 495
 496     def c_type(self) -> str:
 497         return c_name(self.name) + POINTER_SUFFIX
 498
 499     def json_type(self) -> str:
 500         return 'array'
 501
 502     def doc_type(self) -> Optional[str]:
 503         elt_doc_type = self.element_type.doc_type()
 504         if not elt_doc_type:
 505             return None
 506         return 'array of ' + elt_doc_type
 507
 508     def visit(self, visitor: QAPISchemaVisitor) -> None:
 509         super().visit(visitor)
 510         visitor.visit_array_type(self.name, self.info, self.ifcond,
 511                                  self.element_type)
 512
 513     def describe(self) -> str:
 514         return "%s type ['%s']" % (self.meta, self._element_type_name)
 515
 516
 517 class QAPISchemaObjectType(QAPISchemaType):
 518     def __init__(
 519         self,
 520         name: str,
 521         info: Optional[QAPISourceInfo],
 522         doc: Optional[QAPIDoc],
 523         ifcond: Optional[QAPISchemaIfCond],
 524         features: Optional[List[QAPISchemaFeature]],
 525         base: Optional[str],
 526         local_members: List[QAPISchemaObjectTypeMember],
 527         branches: Optional[QAPISchemaBranches],
 528     ):
 529         # struct has local_members, optional base, and no branches
 530         # union has base, branches, and no local_members
 531         super().__init__(name, info, doc, ifcond, features)
 532         self.meta = 'union' if branches else 'struct'
 533         for m in local_members:
 534             m.set_defined_in(name)
 535         if branches is not None:
 536             branches.set_defined_in(name)
 537         self._base_name = base
 538         self.base = None
 539         self.local_members = local_members
 540         self.branches = branches
 541         self.members: List[QAPISchemaObjectTypeMember]
 542         self._check_complete = False
 543
 544     def check(self, schema: QAPISchema) -> None:
 545         # This calls another type T's .check() exactly when the C
 546         # struct emitted by gen_object() contains that T's C struct
 547         # (pointers don't count).
 548         if self._check_complete:
 549             # A previous .check() completed: nothing to do
 550             return
 551         if self._checked:
 552             # Recursed: C struct contains itself
 553             raise QAPISemError(self.info,
 554                                "object %s contains itself" % self.name)
 555
 556         super().check(schema)
 557         assert self._checked and not self._check_complete
 558
 559         seen = OrderedDict()
 560         if self._base_name:
 561             self.base = schema.resolve_type(self._base_name, self.info,
 562                                             "'base'")
 563             if (not isinstance(self.base, QAPISchemaObjectType)
 564                     or self.base.branches):
 565                 raise QAPISemError(
 566                     self.info,
 567                     "'base' requires a struct type, %s isn't"
 568                     % self.base.describe())
 569             self.base.check(schema)
 570             self.base.check_clash(self.info, seen)
 571         for m in self.local_members:
 572             m.check(schema)
 573             m.check_clash(self.info, seen)
 574
 575         # self.check_clash() works in terms of the supertype, but
 576         # self.members is declared List[QAPISchemaObjectTypeMember].
 577         # Cast down to the subtype.
 578         members = cast(List[QAPISchemaObjectTypeMember], list(seen.values()))
 579
 580         if self.branches:
 581             self.branches.check(schema, seen)
 582             self.branches.check_clash(self.info, seen)
 583
 584         self.members = members
 585         self._check_complete = True  # mark completed
 586
 587     # Check that the members of this type do not cause duplicate JSON members,
 588     # and update seen to track the members seen so far. Report any errors
 589     # on behalf of info, which is not necessarily self.info
 590     def check_clash(
 591         self,
 592         info: Optional[QAPISourceInfo],
 593         seen: Dict[str, QAPISchemaMember],
 594     ) -> None:
 595         assert self._checked
 596         for m in self.members:
 597             m.check_clash(info, seen)
 598         if self.branches:
 599             self.branches.check_clash(info, seen)
 600
 601     def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
 602         super().connect_doc(doc)
 603         doc = doc or self.doc
 604         if self.base and self.base.is_implicit():
 605             self.base.connect_doc(doc)
 606         for m in self.local_members:
 607             m.connect_doc(doc)
 608
 609     def is_implicit(self) -> bool:
 610         # See QAPISchema._make_implicit_object_type(), as well as
 611         # _def_predefineds()
 612         return self.name.startswith('q_')
 613
 614     def is_empty(self) -> bool:
 615         return not self.members and not self.branches
 616
 617     def has_conditional_members(self) -> bool:
 618         return any(m.ifcond.is_present() for m in self.members)
 619
 620     def c_name(self) -> str:
 621         assert self.name != 'q_empty'
 622         return super().c_name()
 623
 624     def c_type(self) -> str:
 625         assert not self.is_implicit()
 626         return c_name(self.name) + POINTER_SUFFIX
 627
 628     def c_unboxed_type(self) -> str:
 629         return c_name(self.name)
 630
 631     def json_type(self) -> str:
 632         return 'object'
 633
 634     def visit(self, visitor: QAPISchemaVisitor) -> None:
 635         super().visit(visitor)
 636         visitor.visit_object_type(
 637             self.name, self.info, self.ifcond, self.features,
 638             self.base, self.local_members, self.branches)
 639         visitor.visit_object_type_flat(
 640             self.name, self.info, self.ifcond, self.features,
 641             self.members, self.branches)
 642
 643
 644 class QAPISchemaAlternateType(QAPISchemaType):
 645     meta = 'alternate'
 646
 647     def __init__(
 648         self,
 649         name: str,
 650         info: QAPISourceInfo,
 651         doc: Optional[QAPIDoc],
 652         ifcond: Optional[QAPISchemaIfCond],
 653         features: List[QAPISchemaFeature],
 654         alternatives: QAPISchemaAlternatives,
 655     ):
 656         super().__init__(name, info, doc, ifcond, features)
 657         assert alternatives.tag_member
 658         alternatives.set_defined_in(name)
 659         alternatives.tag_member.set_defined_in(self.name)
 660         self.alternatives = alternatives
 661
 662     def check(self, schema: QAPISchema) -> None:
 663         super().check(schema)
 664         self.alternatives.tag_member.check(schema)
 665         # Not calling self.alternatives.check_clash(), because there's
 666         # nothing to clash with
 667         self.alternatives.check(schema, {})
 668         # Alternate branch names have no relation to the tag enum values;
 669         # so we have to check for potential name collisions ourselves.
 670         seen: Dict[str, QAPISchemaMember] = {}
 671         types_seen: Dict[str, str] = {}
 672         for v in self.alternatives.variants:
 673             v.check_clash(self.info, seen)
 674             qtype = v.type.alternate_qtype()
 675             if not qtype:
 676                 raise QAPISemError(
 677                     self.info,
 678                     "%s cannot use %s"
 679                     % (v.describe(self.info), v.type.describe()))
 680             conflicting = set([qtype])
 681             if qtype == 'QTYPE_QSTRING':
 682                 if isinstance(v.type, QAPISchemaEnumType):
 683                     for m in v.type.members:
 684                         if m.name in ['on', 'off']:
 685                             conflicting.add('QTYPE_QBOOL')
 686                         if re.match(r'[-+0-9.]', m.name):
 687                             # lazy, could be tightened
 688                             conflicting.add('QTYPE_QNUM')
 689                 else:
 690                     conflicting.add('QTYPE_QNUM')
 691                     conflicting.add('QTYPE_QBOOL')
 692             for qt in conflicting:
 693                 if qt in types_seen:
 694                     raise QAPISemError(
 695                         self.info,
 696                         "%s can't be distinguished from '%s'"
 697                         % (v.describe(self.info), types_seen[qt]))
 698                 types_seen[qt] = v.name
 699
 700     def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
 701         super().connect_doc(doc)
 702         doc = doc or self.doc
 703         for v in self.alternatives.variants:
 704             v.connect_doc(doc)
 705
 706     def c_type(self) -> str:
 707         return c_name(self.name) + POINTER_SUFFIX
 708
 709     def json_type(self) -> str:
 710         return 'value'
 711
 712     def visit(self, visitor: QAPISchemaVisitor) -> None:
 713         super().visit(visitor)
 714         visitor.visit_alternate_type(
 715             self.name, self.info, self.ifcond, self.features,
 716             self.alternatives)
 717
 718
 719 class QAPISchemaVariants:
 720     def __init__(
 721         self,
 722         info: QAPISourceInfo,
 723         variants: List[QAPISchemaVariant],
 724     ):
 725         self.info = info
 726         self._tag_member: Optional[QAPISchemaObjectTypeMember] = None
 727         self.variants = variants
 728
 729     @property
 730     def tag_member(self) -> QAPISchemaObjectTypeMember:
 731         if self._tag_member is None:
 732             raise RuntimeError(
 733                 "QAPISchemaVariants has no tag_member property until "
 734                 "after check() has been run."
 735             )
 736         return self._tag_member
 737
 738     def set_defined_in(self, name: str) -> None:
 739         for v in self.variants:
 740             v.set_defined_in(name)
 741
 742     def check(
 743             self, schema: QAPISchema, seen: Dict[str, QAPISchemaMember]
 744     ) -> None:
 745         for v in self.variants:
 746             v.check(schema)
 747
 748
 749 class QAPISchemaBranches(QAPISchemaVariants):
 750     def __init__(self,
 751                  info: QAPISourceInfo,
 752                  variants: List[QAPISchemaVariant],
 753                  tag_name: str):
 754         super().__init__(info, variants)
 755         self._tag_name = tag_name
 756
 757     def check(
 758             self, schema: QAPISchema, seen: Dict[str, QAPISchemaMember]
 759     ) -> None:
 760         # We need to narrow the member type:
 761         tmp = seen.get(c_name(self._tag_name))
 762         assert tmp is None or isinstance(tmp, QAPISchemaObjectTypeMember)
 763         self._tag_member = tmp
 764
 765         base = "'base'"
 766         # Pointing to the base type when not implicit would be
 767         # nice, but we don't know it here
 768         if not self._tag_member or self._tag_name != self._tag_member.name:
 769             raise QAPISemError(
 770                 self.info,
 771                 "discriminator '%s' is not a member of %s"
 772                 % (self._tag_name, base))
 773         # Here we do:
 774         assert self.tag_member.defined_in
 775         base_type = schema.lookup_type(self.tag_member.defined_in)
 776         assert base_type
 777         if not base_type.is_implicit():
 778             base = "base type '%s'" % self.tag_member.defined_in
 779         if not isinstance(self.tag_member.type, QAPISchemaEnumType):
 780             raise QAPISemError(
 781                 self.info,
 782                 "discriminator member '%s' of %s must be of enum type"
 783                 % (self._tag_name, base))
 784         if self.tag_member.optional:
 785             raise QAPISemError(
 786                 self.info,
 787                 "discriminator member '%s' of %s must not be optional"
 788                 % (self._tag_name, base))
 789         if self.tag_member.ifcond.is_present():
 790             raise QAPISemError(
 791                 self.info,
 792                 "discriminator member '%s' of %s must not be conditional"
 793                 % (self._tag_name, base))
 794         # branches that are not explicitly covered get an empty type
 795         assert self.tag_member.defined_in
 796         cases = {v.name for v in self.variants}
 797         for m in self.tag_member.type.members:
 798             if m.name not in cases:
 799                 v = QAPISchemaVariant(m.name, self.info,
 800                                       'q_empty', m.ifcond)
 801                 v.set_defined_in(self.tag_member.defined_in)
 802                 self.variants.append(v)
 803         if not self.variants:
 804             raise QAPISemError(self.info, "union has no branches")
 805         for v in self.variants:
 806             v.check(schema)
 807             # Union names must match enum values; alternate names are
 808             # checked separately. Use 'seen' to tell the two apart.
 809             if seen:
 810                 if v.name not in self.tag_member.type.member_names():
 811                     raise QAPISemError(
 812                         self.info,
 813                         "branch '%s' is not a value of %s"
 814                         % (v.name, self.tag_member.type.describe()))
 815                 if not isinstance(v.type, QAPISchemaObjectType):
 816                     raise QAPISemError(
 817                         self.info,
 818                         "%s cannot use %s"
 819                         % (v.describe(self.info), v.type.describe()))
 820                 v.type.check(schema)
 821
 822     def check_clash(
 823         self,
 824         info: Optional[QAPISourceInfo],
 825         seen: Dict[str, QAPISchemaMember],
 826     ) -> None:
 827         for v in self.variants:
 828             # Reset seen map for each variant, since qapi names from one
 829             # branch do not affect another branch.
 830             #
 831             # v.type's typing is enforced in check() above.
 832             assert isinstance(v.type, QAPISchemaObjectType)
 833             v.type.check_clash(info, dict(seen))
 834
 835
 836 class QAPISchemaAlternatives(QAPISchemaVariants):
 837     def __init__(self,
 838                  info: QAPISourceInfo,
 839                  variants: List[QAPISchemaVariant],
 840                  tag_member: QAPISchemaObjectTypeMember):
 841         super().__init__(info, variants)
 842         self._tag_member = tag_member
 843
 844     def check(
 845             self, schema: QAPISchema, seen: Dict[str, QAPISchemaMember]
 846     ) -> None:
 847         super().check(schema, seen)
 848         assert isinstance(self.tag_member.type, QAPISchemaEnumType)
 849         assert not self.tag_member.optional
 850         assert not self.tag_member.ifcond.is_present()
 851
 852
 853 class QAPISchemaMember:
 854     """ Represents object members, enum members and features """
 855     role = 'member'
 856
 857     def __init__(
 858         self,
 859         name: str,
 860         info: Optional[QAPISourceInfo],
 861         ifcond: Optional[QAPISchemaIfCond] = None,
 862     ):
 863         self.name = name
 864         self.info = info
 865         self.ifcond = ifcond or QAPISchemaIfCond()
 866         self.defined_in: Optional[str] = None
 867
 868     def set_defined_in(self, name: str) -> None:
 869         assert not self.defined_in
 870         self.defined_in = name
 871
 872     def check_clash(
 873         self,
 874         info: Optional[QAPISourceInfo],
 875         seen: Dict[str, QAPISchemaMember],
 876     ) -> None:
 877         cname = c_name(self.name)
 878         if cname in seen:
 879             raise QAPISemError(
 880                 info,
 881                 "%s collides with %s"
 882                 % (self.describe(info), seen[cname].describe(info)))
 883         seen[cname] = self
 884
 885     def connect_doc(self, doc: Optional[QAPIDoc]) -> None:
 886         if doc:
 887             doc.connect_member(self)
 888
 889     def describe(self, info: Optional[QAPISourceInfo]) -> str:
 890         role = self.role
 891         meta = 'type'
 892         defined_in = self.defined_in
 893         assert defined_in
 894
 895         if defined_in.startswith('q_obj_'):
 896             # See QAPISchema._make_implicit_object_type() - reverse the
 897             # mapping there to create a nice human-readable description
 898             defined_in = defined_in[6:]
 899             if defined_in.endswith('-arg'):
 900                 # Implicit type created for a command's dict 'data'
 901                 assert role == 'member'
 902                 role = 'parameter'
 903                 meta = 'command'
 904                 defined_in = defined_in[:-4]
 905             elif defined_in.endswith('-base'):
 906                 # Implicit type created for a union's dict 'base'
 907                 role = 'base ' + role
 908                 defined_in = defined_in[:-5]
 909             else:
 910                 assert False
 911
 912         assert info is not None
 913         if defined_in != info.defn_name:
 914             return "%s '%s' of %s '%s'" % (role, self.name, meta, defined_in)
 915         return "%s '%s'" % (role, self.name)
 916
 917
 918 class QAPISchemaEnumMember(QAPISchemaMember):
 919     role = 'value'
 920
 921     def __init__(
 922         self,
 923         name: str,
 924         info: Optional[QAPISourceInfo],
 925         ifcond: Optional[QAPISchemaIfCond] = None,
 926         features: Optional[List[QAPISchemaFeature]] = None,
 927     ):
 928         super().__init__(name, info, ifcond)
 929         for f in features or []:
 930             f.set_defined_in(name)
 931         self.features = features or []
 932
 933     def connect_doc(self, doc: Optional[QAPIDoc]) -> None:
 934         super().connect_doc(doc)
 935         if doc:
 936             for f in self.features:
 937                 doc.connect_feature(f)
 938
 939
 940 class QAPISchemaFeature(QAPISchemaMember):
 941     role = 'feature'
 942
 943     def is_special(self) -> bool:
 944         return self.name in ('deprecated', 'unstable')
 945
 946
 947 class QAPISchemaObjectTypeMember(QAPISchemaMember):
 948     def __init__(
 949         self,
 950         name: str,
 951         info: QAPISourceInfo,
 952         typ: str,
 953         optional: bool,
 954         ifcond: Optional[QAPISchemaIfCond] = None,
 955         features: Optional[List[QAPISchemaFeature]] = None,
 956     ):
 957         super().__init__(name, info, ifcond)
 958         for f in features or []:
 959             f.set_defined_in(name)
 960         self._type_name = typ
 961         self.type: QAPISchemaType  # set during check()
 962         self.optional = optional
 963         self.features = features or []
 964
 965     def need_has(self) -> bool:
 966         return self.optional and self.type.need_has_if_optional()
 967
 968     def check(self, schema: QAPISchema) -> None:
 969         assert self.defined_in
 970         self.type = schema.resolve_type(self._type_name, self.info,
 971                                         self.describe)
 972         seen: Dict[str, QAPISchemaMember] = {}
 973         for f in self.features:
 974             f.check_clash(self.info, seen)
 975
 976     def connect_doc(self, doc: Optional[QAPIDoc]) -> None:
 977         super().connect_doc(doc)
 978         if doc:
 979             for f in self.features:
 980                 doc.connect_feature(f)
 981
 982
 983 class QAPISchemaVariant(QAPISchemaObjectTypeMember):
 984     role = 'branch'
 985
 986     def __init__(
 987         self,
 988         name: str,
 989         info: QAPISourceInfo,
 990         typ: str,
 991         ifcond: QAPISchemaIfCond,
 992     ):
 993         super().__init__(name, info, typ, False, ifcond)
 994
 995
 996 class QAPISchemaCommand(QAPISchemaDefinition):
 997     meta = 'command'
 998
 999     def __init__(
1000         self,
1001         name: str,
1002         info: QAPISourceInfo,
1003         doc: Optional[QAPIDoc],
1004         ifcond: QAPISchemaIfCond,
1005         features: List[QAPISchemaFeature],
1006         arg_type: Optional[str],
1007         ret_type: Optional[str],
1008         gen: bool,
1009         success_response: bool,
1010         boxed: bool,
1011         allow_oob: bool,
1012         allow_preconfig: bool,
1013         coroutine: bool,
1014     ):
1015         super().__init__(name, info, doc, ifcond, features)
1016         self._arg_type_name = arg_type
1017         self.arg_type: Optional[QAPISchemaObjectType] = None
1018         self._ret_type_name = ret_type
1019         self.ret_type: Optional[QAPISchemaType] = None
1020         self.gen = gen
1021         self.success_response = success_response
1022         self.boxed = boxed
1023         self.allow_oob = allow_oob
1024         self.allow_preconfig = allow_preconfig
1025         self.coroutine = coroutine
1026
1027     def check(self, schema: QAPISchema) -> None:
1028         assert self.info is not None
1029         super().check(schema)
1030         if self._arg_type_name:
1031             arg_type = schema.resolve_type(
1032                 self._arg_type_name, self.info, "command's 'data'")
1033             if not isinstance(arg_type, QAPISchemaObjectType):
1034                 raise QAPISemError(
1035                     self.info,
1036                     "command's 'data' cannot take %s"
1037                     % arg_type.describe())
1038             self.arg_type = arg_type
1039             if self.arg_type.branches and not self.boxed:
1040                 raise QAPISemError(
1041                     self.info,
1042                     "command's 'data' can take %s only with 'boxed': true"
1043                     % self.arg_type.describe())
1044             self.arg_type.check(schema)
1045             if self.arg_type.has_conditional_members() and not self.boxed:
1046                 raise QAPISemError(
1047                     self.info,
1048                     "conditional command arguments require 'boxed': true")
1049         if self._ret_type_name:
1050             self.ret_type = schema.resolve_type(
1051                 self._ret_type_name, self.info, "command's 'returns'")
1052             if self.name not in self.info.pragma.command_returns_exceptions:
1053                 typ = self.ret_type
1054                 if isinstance(typ, QAPISchemaArrayType):
1055                     typ = typ.element_type
1056                 if not isinstance(typ, QAPISchemaObjectType):
1057                     raise QAPISemError(
1058                         self.info,
1059                         "command's 'returns' cannot take %s"
1060                         % self.ret_type.describe())
1061
1062     def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
1063         super().connect_doc(doc)
1064         doc = doc or self.doc
1065         if doc:
1066             if self.arg_type and self.arg_type.is_implicit():
1067                 self.arg_type.connect_doc(doc)
1068
1069     def visit(self, visitor: QAPISchemaVisitor) -> None:
1070         super().visit(visitor)
1071         visitor.visit_command(
1072             self.name, self.info, self.ifcond, self.features,
1073             self.arg_type, self.ret_type, self.gen, self.success_response,
1074             self.boxed, self.allow_oob, self.allow_preconfig,
1075             self.coroutine)
1076
1077
1078 class QAPISchemaEvent(QAPISchemaDefinition):
1079     meta = 'event'
1080
1081     def __init__(
1082         self,
1083         name: str,
1084         info: QAPISourceInfo,
1085         doc: Optional[QAPIDoc],
1086         ifcond: QAPISchemaIfCond,
1087         features: List[QAPISchemaFeature],
1088         arg_type: Optional[str],
1089         boxed: bool,
1090     ):
1091         super().__init__(name, info, doc, ifcond, features)
1092         self._arg_type_name = arg_type
1093         self.arg_type: Optional[QAPISchemaObjectType] = None
1094         self.boxed = boxed
1095
1096     def check(self, schema: QAPISchema) -> None:
1097         super().check(schema)
1098         if self._arg_type_name:
1099             typ = schema.resolve_type(
1100                 self._arg_type_name, self.info, "event's 'data'")
1101             if not isinstance(typ, QAPISchemaObjectType):
1102                 raise QAPISemError(
1103                     self.info,
1104                     "event's 'data' cannot take %s"
1105                     % typ.describe())
1106             self.arg_type = typ
1107             if self.arg_type.branches and not self.boxed:
1108                 raise QAPISemError(
1109                     self.info,
1110                     "event's 'data' can take %s only with 'boxed': true"
1111                     % self.arg_type.describe())
1112             self.arg_type.check(schema)
1113             if self.arg_type.has_conditional_members() and not self.boxed:
1114                 raise QAPISemError(
1115                     self.info,
1116                     "conditional event arguments require 'boxed': true")
1117
1118     def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
1119         super().connect_doc(doc)
1120         doc = doc or self.doc
1121         if doc:
1122             if self.arg_type and self.arg_type.is_implicit():
1123                 self.arg_type.connect_doc(doc)
1124
1125     def visit(self, visitor: QAPISchemaVisitor) -> None:
1126         super().visit(visitor)
1127         visitor.visit_event(
1128             self.name, self.info, self.ifcond, self.features,
1129             self.arg_type, self.boxed)
1130
1131
1132 class QAPISchema:
1133     def __init__(self, fname: str):
1134         self.fname = fname
1135
1136         try:
1137             parser = QAPISchemaParser(fname)
1138         except OSError as err:
1139             raise QAPIError(
1140                 f"can't read schema file '{fname}': {err.strerror}"
1141             ) from err
1142
1143         exprs = check_exprs(parser.exprs)
1144         self.docs = parser.docs
1145         self._entity_list: List[QAPISchemaEntity] = []
1146         self._entity_dict: Dict[str, QAPISchemaDefinition] = {}
1147         self._module_dict: Dict[str, QAPISchemaModule] = OrderedDict()
1148         self._schema_dir = os.path.dirname(fname)
1149         self._make_module(QAPISchemaModule.BUILTIN_MODULE_NAME)
1150         self._make_module(fname)
1151         self._predefining = True
1152         self._def_predefineds()
1153         self._predefining = False
1154         self._def_exprs(exprs)
1155         self.check()
1156
1157     def _def_entity(self, ent: QAPISchemaEntity) -> None:
1158         self._entity_list.append(ent)
1159
1160     def _def_definition(self, defn: QAPISchemaDefinition) -> None:
1161         # Only the predefined types are allowed to not have info
1162         assert defn.info or self._predefining
1163         self._def_entity(defn)
1164         # TODO reject names that differ only in '_' vs. '.'  vs. '-',
1165         # because they're liable to clash in generated C.
1166         other_defn = self._entity_dict.get(defn.name)
1167         if other_defn:
1168             if other_defn.info:
1169                 where = QAPISourceError(other_defn.info, "previous definition")
1170                 raise QAPISemError(
1171                     defn.info,
1172                     "'%s' is already defined\n%s" % (defn.name, where))
1173             raise QAPISemError(
1174                 defn.info, "%s is already defined" % other_defn.describe())
1175         self._entity_dict[defn.name] = defn
1176
1177     def lookup_entity(self,name: str) -> Optional[QAPISchemaEntity]:
1178         return self._entity_dict.get(name)
1179
1180     def lookup_type(self, name: str) -> Optional[QAPISchemaType]:
1181         typ = self.lookup_entity(name)
1182         if isinstance(typ, QAPISchemaType):
1183             return typ
1184         return None
1185
1186     def resolve_type(
1187         self,
1188         name: str,
1189         info: Optional[QAPISourceInfo],
1190         what: Union[None, str, Callable[[QAPISourceInfo], str]],
1191     ) -> QAPISchemaType:
1192         typ = self.lookup_type(name)
1193         if not typ:
1194             assert info and what  # built-in types must not fail lookup
1195             if callable(what):
1196                 what = what(info)
1197             raise QAPISemError(
1198                 info, "%s uses unknown type '%s'" % (what, name))
1199         return typ
1200
1201     def _module_name(self, fname: str) -> str:
1202         if QAPISchemaModule.is_system_module(fname):
1203             return fname
1204         return os.path.relpath(fname, self._schema_dir)
1205
1206     def _make_module(self, fname: str) -> QAPISchemaModule:
1207         name = self._module_name(fname)
1208         if name not in self._module_dict:
1209             self._module_dict[name] = QAPISchemaModule(name)
1210         return self._module_dict[name]
1211
1212     def module_by_fname(self, fname: str) -> QAPISchemaModule:
1213         name = self._module_name(fname)
1214         return self._module_dict[name]
1215
1216     def _def_include(self, expr: QAPIExpression) -> None:
1217         include = expr['include']
1218         assert expr.doc is None
1219         self._def_entity(
1220             QAPISchemaInclude(self._make_module(include), expr.info))
1221
1222     def _def_builtin_type(
1223         self, name: str, json_type: str, c_type: str
1224     ) -> None:
1225         self._def_definition(QAPISchemaBuiltinType(name, json_type, c_type))
1226         # Instantiating only the arrays that are actually used would
1227         # be nice, but we can't as long as their generated code
1228         # (qapi-builtin-types.[ch]) may be shared by some other
1229         # schema.
1230         self._make_array_type(name, None)
1231
1232     def _def_predefineds(self) -> None:
1233         for t in [('str',    'string',  'char' + POINTER_SUFFIX),
1234                   ('number', 'number',  'double'),
1235                   ('int',    'int',     'int64_t'),
1236                   ('int8',   'int',     'int8_t'),
1237                   ('int16',  'int',     'int16_t'),
1238                   ('int32',  'int',     'int32_t'),
1239                   ('int64',  'int',     'int64_t'),
1240                   ('uint8',  'int',     'uint8_t'),
1241                   ('uint16', 'int',     'uint16_t'),
1242                   ('uint32', 'int',     'uint32_t'),
1243                   ('uint64', 'int',     'uint64_t'),
1244                   ('size',   'int',     'uint64_t'),
1245                   ('bool',   'boolean', 'bool'),
1246                   ('any',    'value',   'QObject' + POINTER_SUFFIX),
1247                   ('null',   'null',    'QNull' + POINTER_SUFFIX)]:
1248             self._def_builtin_type(*t)
1249         self.the_empty_object_type = QAPISchemaObjectType(
1250             'q_empty', None, None, None, None, None, [], None)
1251         self._def_definition(self.the_empty_object_type)
1252
1253         qtypes = ['none', 'qnull', 'qnum', 'qstring', 'qdict', 'qlist',
1254                   'qbool']
1255         qtype_values = self._make_enum_members(
1256             [{'name': n} for n in qtypes], None)
1257
1258         self._def_definition(QAPISchemaEnumType(
1259             'QType', None, None, None, None, qtype_values, 'QTYPE'))
1260
1261     def _make_features(
1262         self,
1263         features: Optional[List[Dict[str, Any]]],
1264         info: Optional[QAPISourceInfo],
1265     ) -> List[QAPISchemaFeature]:
1266         if features is None:
1267             return []
1268         return [QAPISchemaFeature(f['name'], info,
1269                                   QAPISchemaIfCond(f.get('if')))
1270                 for f in features]
1271
1272     def _make_enum_member(
1273         self,
1274         name: str,
1275         ifcond: Optional[Union[str, Dict[str, Any]]],
1276         features: Optional[List[Dict[str, Any]]],
1277         info: Optional[QAPISourceInfo],
1278     ) -> QAPISchemaEnumMember:
1279         return QAPISchemaEnumMember(name, info,
1280                                     QAPISchemaIfCond(ifcond),
1281                                     self._make_features(features, info))
1282
1283     def _make_enum_members(
1284         self, values: List[Dict[str, Any]], info: Optional[QAPISourceInfo]
1285     ) -> List[QAPISchemaEnumMember]:
1286         return [self._make_enum_member(v['name'], v.get('if'),
1287                                        v.get('features'), info)
1288                 for v in values]
1289
1290     def _make_array_type(
1291         self, element_type: str, info: Optional[QAPISourceInfo]
1292     ) -> str:
1293         name = element_type + 'List'    # reserved by check_defn_name_str()
1294         if not self.lookup_type(name):
1295             self._def_definition(QAPISchemaArrayType(
1296                 name, info, element_type))
1297         return name
1298
1299     def _make_implicit_object_type(
1300         self,
1301         name: str,
1302         info: QAPISourceInfo,
1303         ifcond: QAPISchemaIfCond,
1304         role: str,
1305         members: List[QAPISchemaObjectTypeMember],
1306     ) -> Optional[str]:
1307         if not members:
1308             return None
1309         # See also QAPISchemaObjectTypeMember.describe()
1310         name = 'q_obj_%s-%s' % (name, role)
1311         typ = self.lookup_entity(name)
1312         if typ:
1313             assert(isinstance(typ, QAPISchemaObjectType))
1314             # The implicit object type has multiple users.  This can
1315             # only be a duplicate definition, which will be flagged
1316             # later.
1317             pass
1318         else:
1319             self._def_definition(QAPISchemaObjectType(
1320                 name, info, None, ifcond, None, None, members, None))
1321         return name
1322
1323     def _def_enum_type(self, expr: QAPIExpression) -> None:
1324         name = expr['enum']
1325         data = expr['data']
1326         prefix = expr.get('prefix')
1327         ifcond = QAPISchemaIfCond(expr.get('if'))
1328         info = expr.info
1329         features = self._make_features(expr.get('features'), info)
1330         self._def_definition(QAPISchemaEnumType(
1331             name, info, expr.doc, ifcond, features,
1332             self._make_enum_members(data, info), prefix))
1333
1334     def _make_member(
1335         self,
1336         name: str,
1337         typ: Union[List[str], str],
1338         ifcond: QAPISchemaIfCond,
1339         features: Optional[List[Dict[str, Any]]],
1340         info: QAPISourceInfo,
1341     ) -> QAPISchemaObjectTypeMember:
1342         optional = False
1343         if name.startswith('*'):
1344             name = name[1:]
1345             optional = True
1346         if isinstance(typ, list):
1347             assert len(typ) == 1
1348             typ = self._make_array_type(typ[0], info)
1349         return QAPISchemaObjectTypeMember(name, info, typ, optional, ifcond,
1350                                           self._make_features(features, info))
1351
1352     def _make_members(
1353         self,
1354         data: Dict[str, Any],
1355         info: QAPISourceInfo,
1356     ) -> List[QAPISchemaObjectTypeMember]:
1357         return [self._make_member(key, value['type'],
1358                                   QAPISchemaIfCond(value.get('if')),
1359                                   value.get('features'), info)
1360                 for (key, value) in data.items()]
1361
1362     def _def_struct_type(self, expr: QAPIExpression) -> None:
1363         name = expr['struct']
1364         base = expr.get('base')
1365         data = expr['data']
1366         info = expr.info
1367         ifcond = QAPISchemaIfCond(expr.get('if'))
1368         features = self._make_features(expr.get('features'), info)
1369         self._def_definition(QAPISchemaObjectType(
1370             name, info, expr.doc, ifcond, features, base,
1371             self._make_members(data, info),
1372             None))
1373
1374     def _make_variant(
1375         self,
1376         case: str,
1377         typ: str,
1378         ifcond: QAPISchemaIfCond,
1379         info: QAPISourceInfo,
1380     ) -> QAPISchemaVariant:
1381         if isinstance(typ, list):
1382             assert len(typ) == 1
1383             typ = self._make_array_type(typ[0], info)
1384         return QAPISchemaVariant(case, info, typ, ifcond)
1385
1386     def _def_union_type(self, expr: QAPIExpression) -> None:
1387         name = expr['union']
1388         base = expr['base']
1389         tag_name = expr['discriminator']
1390         data = expr['data']
1391         assert isinstance(data, dict)
1392         info = expr.info
1393         ifcond = QAPISchemaIfCond(expr.get('if'))
1394         features = self._make_features(expr.get('features'), info)
1395         if isinstance(base, dict):
1396             base = self._make_implicit_object_type(
1397                 name, info, ifcond,
1398                 'base', self._make_members(base, info))
1399         variants = [
1400             self._make_variant(key, value['type'],
1401                                QAPISchemaIfCond(value.get('if')),
1402                                info)
1403             for (key, value) in data.items()]
1404         members: List[QAPISchemaObjectTypeMember] = []
1405         self._def_definition(
1406             QAPISchemaObjectType(name, info, expr.doc, ifcond, features,
1407                                  base, members,
1408                                  QAPISchemaBranches(
1409                                      info, variants, tag_name)))
1410
1411     def _def_alternate_type(self, expr: QAPIExpression) -> None:
1412         name = expr['alternate']
1413         data = expr['data']
1414         assert isinstance(data, dict)
1415         ifcond = QAPISchemaIfCond(expr.get('if'))
1416         info = expr.info
1417         features = self._make_features(expr.get('features'), info)
1418         variants = [
1419             self._make_variant(key, value['type'],
1420                                QAPISchemaIfCond(value.get('if')),
1421                                info)
1422             for (key, value) in data.items()]
1423         tag_member = QAPISchemaObjectTypeMember('type', info, 'QType', False)
1424         self._def_definition(
1425             QAPISchemaAlternateType(
1426                 name, info, expr.doc, ifcond, features,
1427                 QAPISchemaAlternatives(info, variants, tag_member)))
1428
1429     def _def_command(self, expr: QAPIExpression) -> None:
1430         name = expr['command']
1431         data = expr.get('data')
1432         rets = expr.get('returns')
1433         gen = expr.get('gen', True)
1434         success_response = expr.get('success-response', True)
1435         boxed = expr.get('boxed', False)
1436         allow_oob = expr.get('allow-oob', False)
1437         allow_preconfig = expr.get('allow-preconfig', False)
1438         coroutine = expr.get('coroutine', False)
1439         ifcond = QAPISchemaIfCond(expr.get('if'))
1440         info = expr.info
1441         features = self._make_features(expr.get('features'), info)
1442         if isinstance(data, OrderedDict):
1443             data = self._make_implicit_object_type(
1444                 name, info, ifcond,
1445                 'arg', self._make_members(data, info))
1446         if isinstance(rets, list):
1447             assert len(rets) == 1
1448             rets = self._make_array_type(rets[0], info)
1449         self._def_definition(
1450             QAPISchemaCommand(name, info, expr.doc, ifcond, features, data,
1451                               rets, gen, success_response, boxed, allow_oob,
1452                               allow_preconfig, coroutine))
1453
1454     def _def_event(self, expr: QAPIExpression) -> None:
1455         name = expr['event']
1456         data = expr.get('data')
1457         boxed = expr.get('boxed', False)
1458         ifcond = QAPISchemaIfCond(expr.get('if'))
1459         info = expr.info
1460         features = self._make_features(expr.get('features'), info)
1461         if isinstance(data, OrderedDict):
1462             data = self._make_implicit_object_type(
1463                 name, info, ifcond,
1464                 'arg', self._make_members(data, info))
1465         self._def_definition(QAPISchemaEvent(name, info, expr.doc, ifcond,
1466                                              features, data, boxed))
1467
1468     def _def_exprs(self, exprs: List[QAPIExpression]) -> None:
1469         for expr in exprs:
1470             if 'enum' in expr:
1471                 self._def_enum_type(expr)
1472             elif 'struct' in expr:
1473                 self._def_struct_type(expr)
1474             elif 'union' in expr:
1475                 self._def_union_type(expr)
1476             elif 'alternate' in expr:
1477                 self._def_alternate_type(expr)
1478             elif 'command' in expr:
1479                 self._def_command(expr)
1480             elif 'event' in expr:
1481                 self._def_event(expr)
1482             elif 'include' in expr:
1483                 self._def_include(expr)
1484             else:
1485                 assert False
1486
1487     def check(self) -> None:
1488         for ent in self._entity_list:
1489             ent.check(self)
1490             ent.connect_doc()
1491         for ent in self._entity_list:
1492             ent.set_module(self)
1493         for doc in self.docs:
1494             doc.check()
1495
1496     def visit(self, visitor: QAPISchemaVisitor) -> None:
1497         visitor.visit_begin(self)
1498         for mod in self._module_dict.values():
1499             mod.visit(visitor)
1500         visitor.visit_end()