Guido van Rossum | 46dbb7d | 2015-05-22 10:14:11 -0700 | [diff] [blame^] | 1 | # TODO: |
| 2 | # - Generic[T, T] is invalid |
| 3 | # - Look for TODO below |
| 4 | |
| 5 | # TODO nits: |
| 6 | # Get rid of asserts that are the caller's fault. |
| 7 | # Docstrings (e.g. ABCs). |
| 8 | |
| 9 | import abc |
| 10 | from abc import abstractmethod, abstractproperty |
| 11 | import collections |
| 12 | import functools |
| 13 | import re as stdlib_re # Avoid confusion with the re we export. |
| 14 | import sys |
| 15 | import types |
| 16 | try: |
| 17 | import collections.abc as collections_abc |
| 18 | except ImportError: |
| 19 | import collections as collections_abc # Fallback for PY3.2. |
| 20 | |
| 21 | |
| 22 | # Please keep __all__ alphabetized within each category. |
| 23 | __all__ = [ |
| 24 | # Super-special typing primitives. |
| 25 | 'Any', |
| 26 | 'Callable', |
| 27 | 'Generic', |
| 28 | 'Optional', |
| 29 | 'TypeVar', |
| 30 | 'Union', |
| 31 | 'Tuple', |
| 32 | |
| 33 | # ABCs (from collections.abc). |
| 34 | 'AbstractSet', # collections.abc.Set. |
| 35 | 'ByteString', |
| 36 | 'Container', |
| 37 | 'Hashable', |
| 38 | 'ItemsView', |
| 39 | 'Iterable', |
| 40 | 'Iterator', |
| 41 | 'KeysView', |
| 42 | 'Mapping', |
| 43 | 'MappingView', |
| 44 | 'MutableMapping', |
| 45 | 'MutableSequence', |
| 46 | 'MutableSet', |
| 47 | 'Sequence', |
| 48 | 'Sized', |
| 49 | 'ValuesView', |
| 50 | |
| 51 | # Structural checks, a.k.a. protocols. |
| 52 | 'Reversible', |
| 53 | 'SupportsAbs', |
| 54 | 'SupportsFloat', |
| 55 | 'SupportsInt', |
| 56 | 'SupportsRound', |
| 57 | |
| 58 | # Concrete collection types. |
| 59 | 'Dict', |
| 60 | 'List', |
| 61 | 'Set', |
| 62 | 'NamedTuple', # Not really a type. |
| 63 | 'Generator', |
| 64 | |
| 65 | # One-off things. |
| 66 | 'AnyStr', |
| 67 | 'cast', |
| 68 | 'get_type_hints', |
| 69 | 'no_type_check', |
| 70 | 'no_type_check_decorator', |
| 71 | 'overload', |
| 72 | |
| 73 | # Submodules. |
| 74 | 'io', |
| 75 | 're', |
| 76 | ] |
| 77 | |
| 78 | |
| 79 | def _qualname(x): |
| 80 | if sys.version_info[:2] >= (3, 3): |
| 81 | return x.__qualname__ |
| 82 | else: |
| 83 | # Fall back to just name. |
| 84 | return x.__name__ |
| 85 | |
| 86 | |
| 87 | class TypingMeta(type): |
| 88 | """Metaclass for every type defined below. |
| 89 | |
| 90 | This overrides __new__() to require an extra keyword parameter |
| 91 | '_root', which serves as a guard against naive subclassing of the |
| 92 | typing classes. Any legitimate class defined using a metaclass |
| 93 | derived from TypingMeta (including internal subclasses created by |
| 94 | e.g. Union[X, Y]) must pass _root=True. |
| 95 | |
| 96 | This also defines a dummy constructor (all the work is done in |
| 97 | __new__) and a nicer repr(). |
| 98 | """ |
| 99 | |
| 100 | _is_protocol = False |
| 101 | |
| 102 | def __new__(cls, name, bases, namespace, *, _root=False): |
| 103 | if not _root: |
| 104 | raise TypeError("Cannot subclass %s" % |
| 105 | (', '.join(map(_type_repr, bases)) or '()')) |
| 106 | return super().__new__(cls, name, bases, namespace) |
| 107 | |
| 108 | def __init__(self, *args, **kwds): |
| 109 | pass |
| 110 | |
| 111 | def _eval_type(self, globalns, localns): |
| 112 | """Override this in subclasses to interpret forward references. |
| 113 | |
| 114 | For example, Union['C'] is internally stored as |
| 115 | Union[_ForwardRef('C')], which should evaluate to _Union[C], |
| 116 | where C is an object found in globalns or localns (searching |
| 117 | localns first, of course). |
| 118 | """ |
| 119 | return self |
| 120 | |
| 121 | def _has_type_var(self): |
| 122 | return False |
| 123 | |
| 124 | def __repr__(self): |
| 125 | return '%s.%s' % (self.__module__, _qualname(self)) |
| 126 | |
| 127 | |
| 128 | class Final: |
| 129 | """Mix-in class to prevent instantiation.""" |
| 130 | |
| 131 | def __new__(self, *args, **kwds): |
| 132 | raise TypeError("Cannot instantiate %r" % self.__class__) |
| 133 | |
| 134 | |
| 135 | class _ForwardRef(TypingMeta): |
| 136 | """Wrapper to hold a forward reference.""" |
| 137 | |
| 138 | def __new__(cls, arg): |
| 139 | if not isinstance(arg, str): |
| 140 | raise TypeError('ForwardRef must be a string -- got %r' % (arg,)) |
| 141 | try: |
| 142 | code = compile(arg, '<string>', 'eval') |
| 143 | except SyntaxError: |
| 144 | raise SyntaxError('ForwardRef must be an expression -- got %r' % |
| 145 | (arg,)) |
| 146 | self = super().__new__(cls, arg, (), {}, _root=True) |
| 147 | self.__forward_arg__ = arg |
| 148 | self.__forward_code__ = code |
| 149 | self.__forward_evaluated__ = False |
| 150 | self.__forward_value__ = None |
| 151 | typing_globals = globals() |
| 152 | frame = sys._getframe(1) |
| 153 | while frame is not None and frame.f_globals is typing_globals: |
| 154 | frame = frame.f_back |
| 155 | assert frame is not None |
| 156 | self.__forward_frame__ = frame |
| 157 | return self |
| 158 | |
| 159 | def _eval_type(self, globalns, localns): |
| 160 | if not isinstance(localns, dict): |
| 161 | raise TypeError('ForwardRef localns must be a dict -- got %r' % |
| 162 | (localns,)) |
| 163 | if not isinstance(globalns, dict): |
| 164 | raise TypeError('ForwardRef globalns must be a dict -- got %r' % |
| 165 | (globalns,)) |
| 166 | if not self.__forward_evaluated__: |
| 167 | if globalns is None and localns is None: |
| 168 | globalns = localns = {} |
| 169 | elif globalns is None: |
| 170 | globalns = localns |
| 171 | elif localns is None: |
| 172 | localns = globalns |
| 173 | self.__forward_value__ = _type_check( |
| 174 | eval(self.__forward_code__, globalns, localns), |
| 175 | "Forward references must evaluate to types.") |
| 176 | self.__forward_evaluated__ = True |
| 177 | return self.__forward_value__ |
| 178 | |
| 179 | def __subclasscheck__(self, cls): |
| 180 | if not self.__forward_evaluated__: |
| 181 | globalns = self.__forward_frame__.f_globals |
| 182 | localns = self.__forward_frame__.f_locals |
| 183 | try: |
| 184 | self._eval_type(globalns, localns) |
| 185 | except NameError: |
| 186 | return False # Too early. |
| 187 | return issubclass(cls, self.__forward_value__) |
| 188 | |
| 189 | def __instancecheck__(self, obj): |
| 190 | if not self.__forward_evaluated__: |
| 191 | globalns = self.__forward_frame__.f_globals |
| 192 | localns = self.__forward_frame__.f_locals |
| 193 | try: |
| 194 | self._eval_type(globalns, localns) |
| 195 | except NameError: |
| 196 | return False # Too early. |
| 197 | return isinstance(obj, self.__forward_value__) |
| 198 | |
| 199 | def __repr__(self): |
| 200 | return '_ForwardRef(%r)' % (self.__forward_arg__,) |
| 201 | |
| 202 | |
| 203 | class _TypeAlias: |
| 204 | """Internal helper class for defining generic variants of concrete types. |
| 205 | |
| 206 | Note that this is not a type; let's call it a pseudo-type. It can |
| 207 | be used in instance and subclass checks, e.g. isinstance(m, Match) |
| 208 | or issubclass(type(m), Match). However, it cannot be itself the |
| 209 | target of an issubclass() call; e.g. issubclass(Match, C) (for |
| 210 | some arbitrary class C) raises TypeError rather than returning |
| 211 | False. |
| 212 | """ |
| 213 | |
| 214 | def __new__(cls, *args, **kwds): |
| 215 | """Constructor. |
| 216 | |
| 217 | This only exists to give a better error message in case |
| 218 | someone tries to subclass a type alias (not a good idea). |
| 219 | """ |
| 220 | if (len(args) == 3 and |
| 221 | isinstance(args[0], str) and |
| 222 | isinstance(args[1], tuple)): |
| 223 | # Close enough. |
| 224 | raise TypeError("A type alias cannot be subclassed") |
| 225 | return object.__new__(cls) |
| 226 | |
| 227 | def __init__(self, name, type_var, impl_type, type_checker): |
| 228 | """Initializer. |
| 229 | |
| 230 | Args: |
| 231 | name: The name, e.g. 'Pattern'. |
| 232 | type_var: The type parameter, e.g. AnyStr, or the |
| 233 | specific type, e.g. str. |
| 234 | impl_type: The implementation type. |
| 235 | type_checker: Function that takes an impl_type instance. |
| 236 | and returns a value that should be a type_var instance. |
| 237 | """ |
| 238 | assert isinstance(name, str), repr(name) |
| 239 | assert isinstance(type_var, type), repr(type_var) |
| 240 | assert isinstance(impl_type, type), repr(impl_type) |
| 241 | assert not isinstance(impl_type, TypingMeta), repr(impl_type) |
| 242 | self.name = name |
| 243 | self.type_var = type_var |
| 244 | self.impl_type = impl_type |
| 245 | self.type_checker = type_checker |
| 246 | |
| 247 | def __repr__(self): |
| 248 | return "%s[%s]" % (self.name, _type_repr(self.type_var)) |
| 249 | |
| 250 | def __getitem__(self, parameter): |
| 251 | assert isinstance(parameter, type), repr(parameter) |
| 252 | if not isinstance(self.type_var, TypeVar): |
| 253 | raise TypeError("%s cannot be further parameterized." % self) |
| 254 | if self.type_var.__constraints__: |
| 255 | if not issubclass(parameter, Union[self.type_var.__constraints__]): |
| 256 | raise TypeError("%s is not a valid substitution for %s." % |
| 257 | (parameter, self.type_var)) |
| 258 | return self.__class__(self.name, parameter, |
| 259 | self.impl_type, self.type_checker) |
| 260 | |
| 261 | def __instancecheck__(self, obj): |
| 262 | return (isinstance(obj, self.impl_type) and |
| 263 | isinstance(self.type_checker(obj), self.type_var)) |
| 264 | |
| 265 | def __subclasscheck__(self, cls): |
| 266 | if cls is Any: |
| 267 | return True |
| 268 | if isinstance(cls, _TypeAlias): |
| 269 | # Covariance. For now, we compare by name. |
| 270 | return (cls.name == self.name and |
| 271 | issubclass(cls.type_var, self.type_var)) |
| 272 | else: |
| 273 | # Note that this is too lenient, because the |
| 274 | # implementation type doesn't carry information about |
| 275 | # whether it is about bytes or str (for example). |
| 276 | return issubclass(cls, self.impl_type) |
| 277 | |
| 278 | |
| 279 | def _has_type_var(t): |
| 280 | return t is not None and isinstance(t, TypingMeta) and t._has_type_var() |
| 281 | |
| 282 | |
| 283 | def _eval_type(t, globalns, localns): |
| 284 | if isinstance(t, TypingMeta): |
| 285 | return t._eval_type(globalns, localns) |
| 286 | else: |
| 287 | return t |
| 288 | |
| 289 | |
| 290 | def _type_check(arg, msg): |
| 291 | """Check that the argument is a type, and return it. |
| 292 | |
| 293 | As a special case, accept None and return type(None) instead. |
| 294 | Also, _TypeAlias instances (e.g. Match, Pattern) are acceptable. |
| 295 | |
| 296 | The msg argument is a human-readable error message, e.g. |
| 297 | |
| 298 | "Union[arg, ...]: arg should be a type." |
| 299 | |
| 300 | We append the repr() of the actual value (truncated to 100 chars). |
| 301 | """ |
| 302 | if arg is None: |
| 303 | return type(None) |
| 304 | if isinstance(arg, str): |
| 305 | arg = _ForwardRef(arg) |
| 306 | if not isinstance(arg, (type, _TypeAlias)): |
| 307 | raise TypeError(msg + " Got %.100r." % (arg,)) |
| 308 | return arg |
| 309 | |
| 310 | |
| 311 | def _type_repr(obj): |
| 312 | """Return the repr() of an object, special-casing types. |
| 313 | |
| 314 | If obj is a type, we return a shorter version than the default |
| 315 | type.__repr__, based on the module and qualified name, which is |
| 316 | typically enough to uniquely identify a type. For everything |
| 317 | else, we fall back on repr(obj). |
| 318 | """ |
| 319 | if isinstance(obj, type) and not isinstance(obj, TypingMeta): |
| 320 | if obj.__module__ == 'builtins': |
| 321 | return _qualname(obj) |
| 322 | else: |
| 323 | return '%s.%s' % (obj.__module__, _qualname(obj)) |
| 324 | else: |
| 325 | return repr(obj) |
| 326 | |
| 327 | |
| 328 | class AnyMeta(TypingMeta): |
| 329 | """Metaclass for Any.""" |
| 330 | |
| 331 | def __new__(cls, name, bases, namespace, _root=False): |
| 332 | self = super().__new__(cls, name, bases, namespace, _root=_root) |
| 333 | return self |
| 334 | |
| 335 | def __instancecheck__(self, instance): |
| 336 | return True |
| 337 | |
| 338 | def __subclasscheck__(self, cls): |
| 339 | if not isinstance(cls, type): |
| 340 | return super().__subclasscheck__(cls) # To TypeError. |
| 341 | return True |
| 342 | |
| 343 | |
| 344 | class Any(Final, metaclass=AnyMeta, _root=True): |
| 345 | """Special type indicating an unconstrained type. |
| 346 | |
| 347 | - Any object is an instance of Any. |
| 348 | - Any class is a subclass of Any. |
| 349 | - As a special case, Any and object are subclasses of each other. |
| 350 | """ |
| 351 | |
| 352 | |
| 353 | class TypeVar(TypingMeta, metaclass=TypingMeta, _root=True): |
| 354 | """Type variable. |
| 355 | |
| 356 | Usage:: |
| 357 | |
| 358 | T = TypeVar('T') # Can be anything |
| 359 | A = TypeVar('A', str, bytes) # Must be str or bytes |
| 360 | |
| 361 | Type variables exist primarily for the benefit of static type |
| 362 | checkers. They serve as the parameters for generic types as well |
| 363 | as for generic function definitions. See class Generic for more |
| 364 | information on generic types. Generic functions work as follows: |
| 365 | |
| 366 | def repeat(x: T, n: int) -> Sequence[T]: |
| 367 | '''Return a list containing n references to x.''' |
| 368 | return [x]*n |
| 369 | |
| 370 | def longest(x: A, y: A) -> A: |
| 371 | '''Return the longest of two strings.''' |
| 372 | return x if len(x) >= len(y) else y |
| 373 | |
| 374 | The latter example's signature is essentially the overloading |
| 375 | of (str, str) -> str and (bytes, bytes) -> bytes. Also note |
| 376 | that if the arguments are instances of some subclass of str, |
| 377 | the return type is still plain str. |
| 378 | |
| 379 | At runtime, isinstance(x, T) will raise TypeError. However, |
| 380 | issubclass(C, T) is true for any class C, and issubclass(str, A) |
| 381 | and issubclass(bytes, A) are true, and issubclass(int, A) is |
| 382 | false. |
| 383 | |
| 384 | Type variables may be marked covariant or contravariant by passing |
| 385 | covariant=True or contravariant=True. See PEP 484 for more |
| 386 | details. By default type variables are invariant. |
| 387 | |
| 388 | Type variables can be introspected. e.g.: |
| 389 | |
| 390 | T.__name__ == 'T' |
| 391 | T.__constraints__ == () |
| 392 | T.__covariant__ == False |
| 393 | T.__contravariant__ = False |
| 394 | A.__constraints__ == (str, bytes) |
| 395 | """ |
| 396 | |
| 397 | def __new__(cls, name, *constraints, bound=None, |
| 398 | covariant=False, contravariant=False): |
| 399 | self = super().__new__(cls, name, (Final,), {}, _root=True) |
| 400 | if covariant and contravariant: |
| 401 | raise ValueError("Bivariant type variables are not supported.") |
| 402 | self.__covariant__ = bool(covariant) |
| 403 | self.__contravariant__ = bool(contravariant) |
| 404 | if constraints and bound is not None: |
| 405 | raise TypeError("Constraints cannot be combined with bound=...") |
| 406 | if constraints and len(constraints) == 1: |
| 407 | raise TypeError("A single constraint is not allowed") |
| 408 | msg = "TypeVar(name, constraint, ...): constraints must be types." |
| 409 | self.__constraints__ = tuple(_type_check(t, msg) for t in constraints) |
| 410 | if bound: |
| 411 | self.__bound__ = _type_check(bound, "Bound must be a type.") |
| 412 | else: |
| 413 | self.__bound__ = None |
| 414 | return self |
| 415 | |
| 416 | def _has_type_var(self): |
| 417 | return True |
| 418 | |
| 419 | def __repr__(self): |
| 420 | if self.__covariant__: |
| 421 | prefix = '+' |
| 422 | elif self.__contravariant__: |
| 423 | prefix = '-' |
| 424 | else: |
| 425 | prefix = '~' |
| 426 | return prefix + self.__name__ |
| 427 | |
| 428 | def __instancecheck__(self, instance): |
| 429 | raise TypeError("Type variables cannot be used with isinstance().") |
| 430 | |
| 431 | def __subclasscheck__(self, cls): |
| 432 | # TODO: Make this raise TypeError too? |
| 433 | if cls is self: |
| 434 | return True |
| 435 | if cls is Any: |
| 436 | return True |
| 437 | if self.__bound__ is not None: |
| 438 | return issubclass(cls, self.__bound__) |
| 439 | if self.__constraints__: |
| 440 | return any(issubclass(cls, c) for c in self.__constraints__) |
| 441 | return True |
| 442 | |
| 443 | |
| 444 | # Some unconstrained type variables. These are used by the container types. |
| 445 | T = TypeVar('T') # Any type. |
| 446 | KT = TypeVar('KT') # Key type. |
| 447 | VT = TypeVar('VT') # Value type. |
| 448 | T_co = TypeVar('T_co', covariant=True) # Any type covariant containers. |
| 449 | V_co = TypeVar('V_co', covariant=True) # Any type covariant containers. |
| 450 | KT_co = TypeVar('KT_co', covariant=True) # Key type covariant containers. |
| 451 | VT_co = TypeVar('VT_co', covariant=True) # Value type covariant containers. |
| 452 | T_contra = TypeVar('T_contra', contravariant=True) # Ditto contravariant. |
| 453 | |
| 454 | # A useful type variable with constraints. This represents string types. |
| 455 | # TODO: What about bytearray, memoryview? |
| 456 | AnyStr = TypeVar('AnyStr', bytes, str) |
| 457 | |
| 458 | |
| 459 | class UnionMeta(TypingMeta): |
| 460 | """Metaclass for Union.""" |
| 461 | |
| 462 | def __new__(cls, name, bases, namespace, parameters=None, _root=False): |
| 463 | if parameters is None: |
| 464 | return super().__new__(cls, name, bases, namespace, _root=_root) |
| 465 | if not isinstance(parameters, tuple): |
| 466 | raise TypeError("Expected parameters=<tuple>") |
| 467 | # Flatten out Union[Union[...], ...] and type-check non-Union args. |
| 468 | params = [] |
| 469 | msg = "Union[arg, ...]: each arg must be a type." |
| 470 | for p in parameters: |
| 471 | if isinstance(p, UnionMeta): |
| 472 | params.extend(p.__union_params__) |
| 473 | else: |
| 474 | params.append(_type_check(p, msg)) |
| 475 | # Weed out strict duplicates, preserving the first of each occurrence. |
| 476 | all_params = set(params) |
| 477 | if len(all_params) < len(params): |
| 478 | new_params = [] |
| 479 | for t in params: |
| 480 | if t in all_params: |
| 481 | new_params.append(t) |
| 482 | all_params.remove(t) |
| 483 | params = new_params |
| 484 | assert not all_params, all_params |
| 485 | # Weed out subclasses. |
| 486 | # E.g. Union[int, Employee, Manager] == Union[int, Employee]. |
| 487 | # If Any or object is present it will be the sole survivor. |
| 488 | # If both Any and object are present, Any wins. |
| 489 | # Never discard type variables, except against Any. |
| 490 | # (In particular, Union[str, AnyStr] != AnyStr.) |
| 491 | all_params = set(params) |
| 492 | for t1 in params: |
| 493 | if t1 is Any: |
| 494 | return Any |
| 495 | if isinstance(t1, TypeVar): |
| 496 | continue |
| 497 | if any(issubclass(t1, t2) |
| 498 | for t2 in all_params - {t1} if not isinstance(t2, TypeVar)): |
| 499 | all_params.remove(t1) |
| 500 | # It's not a union if there's only one type left. |
| 501 | if len(all_params) == 1: |
| 502 | return all_params.pop() |
| 503 | # Create a new class with these params. |
| 504 | self = super().__new__(cls, name, bases, {}, _root=True) |
| 505 | self.__union_params__ = tuple(t for t in params if t in all_params) |
| 506 | self.__union_set_params__ = frozenset(self.__union_params__) |
| 507 | return self |
| 508 | |
| 509 | def _eval_type(self, globalns, localns): |
| 510 | p = tuple(_eval_type(t, globalns, localns) |
| 511 | for t in self.__union_params__) |
| 512 | if p == self.__union_params__: |
| 513 | return self |
| 514 | else: |
| 515 | return self.__class__(self.__name__, self.__bases__, {}, |
| 516 | p, _root=True) |
| 517 | |
| 518 | def _has_type_var(self): |
| 519 | if self.__union_params__: |
| 520 | for t in self.__union_params__: |
| 521 | if _has_type_var(t): |
| 522 | return True |
| 523 | return False |
| 524 | |
| 525 | def __repr__(self): |
| 526 | r = super().__repr__() |
| 527 | if self.__union_params__: |
| 528 | r += '[%s]' % (', '.join(_type_repr(t) |
| 529 | for t in self.__union_params__)) |
| 530 | return r |
| 531 | |
| 532 | def __getitem__(self, parameters): |
| 533 | if self.__union_params__ is not None: |
| 534 | raise TypeError( |
| 535 | "Cannot subscript an existing Union. Use Union[u, t] instead.") |
| 536 | if parameters == (): |
| 537 | raise TypeError("Cannot take a Union of no types.") |
| 538 | if not isinstance(parameters, tuple): |
| 539 | parameters = (parameters,) |
| 540 | return self.__class__(self.__name__, self.__bases__, |
| 541 | dict(self.__dict__), parameters, _root=True) |
| 542 | |
| 543 | def __eq__(self, other): |
| 544 | if not isinstance(other, UnionMeta): |
| 545 | return NotImplemented |
| 546 | return self.__union_set_params__ == other.__union_set_params__ |
| 547 | |
| 548 | def __hash__(self): |
| 549 | return hash(self.__union_set_params__) |
| 550 | |
| 551 | def __instancecheck__(self, instance): |
| 552 | return (self.__union_set_params__ is not None and |
| 553 | any(isinstance(instance, t) for t in self.__union_params__)) |
| 554 | |
| 555 | def __subclasscheck__(self, cls): |
| 556 | if cls is Any: |
| 557 | return True |
| 558 | if self.__union_params__ is None: |
| 559 | return isinstance(cls, UnionMeta) |
| 560 | elif isinstance(cls, UnionMeta): |
| 561 | if cls.__union_params__ is None: |
| 562 | return False |
| 563 | return all(issubclass(c, self) for c in (cls.__union_params__)) |
| 564 | elif isinstance(cls, TypeVar): |
| 565 | if cls in self.__union_params__: |
| 566 | return True |
| 567 | if cls.__constraints__: |
| 568 | return issubclass(Union[cls.__constraints__], self) |
| 569 | return False |
| 570 | else: |
| 571 | return any(issubclass(cls, t) for t in self.__union_params__) |
| 572 | |
| 573 | |
| 574 | class Union(Final, metaclass=UnionMeta, _root=True): |
| 575 | """Union type; Union[X, Y] means either X or Y. |
| 576 | |
| 577 | To define a union, use e.g. Union[int, str]. Details: |
| 578 | |
| 579 | - The arguments must be types and there must be at least one. |
| 580 | |
| 581 | - None as an argument is a special case and is replaced by |
| 582 | type(None). |
| 583 | |
| 584 | - Unions of unions are flattened, e.g.:: |
| 585 | |
| 586 | Union[Union[int, str], float] == Union[int, str, float] |
| 587 | |
| 588 | - Unions of a single argument vanish, e.g.:: |
| 589 | |
| 590 | Union[int] == int # The constructor actually returns int |
| 591 | |
| 592 | - Redundant arguments are skipped, e.g.:: |
| 593 | |
| 594 | Union[int, str, int] == Union[int, str] |
| 595 | |
| 596 | - When comparing unions, the argument order is ignored, e.g.:: |
| 597 | |
| 598 | Union[int, str] == Union[str, int] |
| 599 | |
| 600 | - When two arguments have a subclass relationship, the least |
| 601 | derived argument is kept, e.g.:: |
| 602 | |
| 603 | class Employee: pass |
| 604 | class Manager(Employee): pass |
| 605 | Union[int, Employee, Manager] == Union[int, Employee] |
| 606 | Union[Manager, int, Employee] == Union[int, Employee] |
| 607 | Union[Employee, Manager] == Employee |
| 608 | |
| 609 | - Corollary: if Any is present it is the sole survivor, e.g.:: |
| 610 | |
| 611 | Union[int, Any] == Any |
| 612 | |
| 613 | - Similar for object:: |
| 614 | |
| 615 | Union[int, object] == object |
| 616 | |
| 617 | - To cut a tie: Union[object, Any] == Union[Any, object] == Any. |
| 618 | |
| 619 | - You cannot subclass or instantiate a union. |
| 620 | |
| 621 | - You cannot write Union[X][Y] (what would it mean?). |
| 622 | |
| 623 | - You can use Optional[X] as a shorthand for Union[X, None]. |
| 624 | """ |
| 625 | |
| 626 | # Unsubscripted Union type has params set to None. |
| 627 | __union_params__ = None |
| 628 | __union_set_params__ = None |
| 629 | |
| 630 | |
| 631 | class OptionalMeta(TypingMeta): |
| 632 | """Metaclass for Optional.""" |
| 633 | |
| 634 | def __new__(cls, name, bases, namespace, _root=False): |
| 635 | return super().__new__(cls, name, bases, namespace, _root=_root) |
| 636 | |
| 637 | def __getitem__(self, arg): |
| 638 | arg = _type_check(arg, "Optional[t] requires a single type.") |
| 639 | return Union[arg, type(None)] |
| 640 | |
| 641 | |
| 642 | class Optional(Final, metaclass=OptionalMeta, _root=True): |
| 643 | """Optional type. |
| 644 | |
| 645 | Optional[X] is equivalent to Union[X, type(None)]. |
| 646 | """ |
| 647 | |
| 648 | |
| 649 | class TupleMeta(TypingMeta): |
| 650 | """Metaclass for Tuple.""" |
| 651 | |
| 652 | def __new__(cls, name, bases, namespace, parameters=None, |
| 653 | use_ellipsis=False, _root=False): |
| 654 | self = super().__new__(cls, name, bases, namespace, _root=_root) |
| 655 | self.__tuple_params__ = parameters |
| 656 | self.__tuple_use_ellipsis__ = use_ellipsis |
| 657 | return self |
| 658 | |
| 659 | def _has_type_var(self): |
| 660 | if self.__tuple_params__: |
| 661 | for t in self.__tuple_params__: |
| 662 | if _has_type_var(t): |
| 663 | return True |
| 664 | return False |
| 665 | |
| 666 | def _eval_type(self, globalns, localns): |
| 667 | tp = self.__tuple_params__ |
| 668 | if tp is None: |
| 669 | return self |
| 670 | p = tuple(_eval_type(t, globalns, localns) for t in tp) |
| 671 | if p == self.__tuple_params__: |
| 672 | return self |
| 673 | else: |
| 674 | return self.__class__(self.__name__, self.__bases__, {}, |
| 675 | p, _root=True) |
| 676 | |
| 677 | def __repr__(self): |
| 678 | r = super().__repr__() |
| 679 | if self.__tuple_params__ is not None: |
| 680 | params = [_type_repr(p) for p in self.__tuple_params__] |
| 681 | if self.__tuple_use_ellipsis__: |
| 682 | params.append('...') |
| 683 | r += '[%s]' % ( |
| 684 | ', '.join(params)) |
| 685 | return r |
| 686 | |
| 687 | def __getitem__(self, parameters): |
| 688 | if self.__tuple_params__ is not None: |
| 689 | raise TypeError("Cannot re-parameterize %r" % (self,)) |
| 690 | if not isinstance(parameters, tuple): |
| 691 | parameters = (parameters,) |
| 692 | if len(parameters) == 2 and parameters[1] == Ellipsis: |
| 693 | parameters = parameters[:1] |
| 694 | use_ellipsis = True |
| 695 | msg = "Tuple[t, ...]: t must be a type." |
| 696 | else: |
| 697 | use_ellipsis = False |
| 698 | msg = "Tuple[t0, t1, ...]: each t must be a type." |
| 699 | parameters = tuple(_type_check(p, msg) for p in parameters) |
| 700 | return self.__class__(self.__name__, self.__bases__, |
| 701 | dict(self.__dict__), parameters, |
| 702 | use_ellipsis=use_ellipsis, _root=True) |
| 703 | |
| 704 | def __eq__(self, other): |
| 705 | if not isinstance(other, TupleMeta): |
| 706 | return NotImplemented |
| 707 | return self.__tuple_params__ == other.__tuple_params__ |
| 708 | |
| 709 | def __hash__(self): |
| 710 | return hash(self.__tuple_params__) |
| 711 | |
| 712 | def __instancecheck__(self, t): |
| 713 | if not isinstance(t, tuple): |
| 714 | return False |
| 715 | if self.__tuple_params__ is None: |
| 716 | return True |
| 717 | if self.__tuple_use_ellipsis__: |
| 718 | p = self.__tuple_params__[0] |
| 719 | return all(isinstance(x, p) for x in t) |
| 720 | else: |
| 721 | return (len(t) == len(self.__tuple_params__) and |
| 722 | all(isinstance(x, p) |
| 723 | for x, p in zip(t, self.__tuple_params__))) |
| 724 | |
| 725 | def __subclasscheck__(self, cls): |
| 726 | if cls is Any: |
| 727 | return True |
| 728 | if not isinstance(cls, type): |
| 729 | return super().__subclasscheck__(cls) # To TypeError. |
| 730 | if issubclass(cls, tuple): |
| 731 | return True # Special case. |
| 732 | if not isinstance(cls, TupleMeta): |
| 733 | return super().__subclasscheck__(cls) # False. |
| 734 | if self.__tuple_params__ is None: |
| 735 | return True |
| 736 | if cls.__tuple_params__ is None: |
| 737 | return False # ??? |
| 738 | if cls.__tuple_use_ellipsis__ != self.__tuple_use_ellipsis__: |
| 739 | return False |
| 740 | # Covariance. |
| 741 | return (len(self.__tuple_params__) == len(cls.__tuple_params__) and |
| 742 | all(issubclass(x, p) |
| 743 | for x, p in zip(cls.__tuple_params__, |
| 744 | self.__tuple_params__))) |
| 745 | |
| 746 | |
| 747 | class Tuple(Final, metaclass=TupleMeta, _root=True): |
| 748 | """Tuple type; Tuple[X, Y] is the cross-product type of X and Y. |
| 749 | |
| 750 | Example: Tuple[T1, T2] is a tuple of two elements corresponding |
| 751 | to type variables T1 and T2. Tuple[int, float, str] is a tuple |
| 752 | of an int, a float and a string. |
| 753 | |
| 754 | To specify a variable-length tuple of homogeneous type, use Sequence[T]. |
| 755 | """ |
| 756 | |
| 757 | |
| 758 | class CallableMeta(TypingMeta): |
| 759 | """Metaclass for Callable.""" |
| 760 | |
| 761 | def __new__(cls, name, bases, namespace, _root=False, |
| 762 | args=None, result=None): |
| 763 | if args is None and result is None: |
| 764 | pass # Must be 'class Callable'. |
| 765 | else: |
| 766 | if args is not Ellipsis: |
| 767 | if not isinstance(args, list): |
| 768 | raise TypeError("Callable[args, result]: " |
| 769 | "args must be a list." |
| 770 | " Got %.100r." % (args,)) |
| 771 | msg = "Callable[[arg, ...], result]: each arg must be a type." |
| 772 | args = tuple(_type_check(arg, msg) for arg in args) |
| 773 | msg = "Callable[args, result]: result must be a type." |
| 774 | result = _type_check(result, msg) |
| 775 | self = super().__new__(cls, name, bases, namespace, _root=_root) |
| 776 | self.__args__ = args |
| 777 | self.__result__ = result |
| 778 | return self |
| 779 | |
| 780 | def _has_type_var(self): |
| 781 | if self.__args__: |
| 782 | for t in self.__args__: |
| 783 | if _has_type_var(t): |
| 784 | return True |
| 785 | return _has_type_var(self.__result__) |
| 786 | |
| 787 | def _eval_type(self, globalns, localns): |
| 788 | if self.__args__ is None and self.__result__ is None: |
| 789 | return self |
| 790 | args = [_eval_type(t, globalns, localns) for t in self.__args__] |
| 791 | result = _eval_type(self.__result__, globalns, localns) |
| 792 | if args == self.__args__ and result == self.__result__: |
| 793 | return self |
| 794 | else: |
| 795 | return self.__class__(self.__name__, self.__bases__, {}, |
| 796 | args=args, result=result, _root=True) |
| 797 | |
| 798 | def __repr__(self): |
| 799 | r = super().__repr__() |
| 800 | if self.__args__ is not None or self.__result__ is not None: |
| 801 | if self.__args__ is Ellipsis: |
| 802 | args_r = '...' |
| 803 | else: |
| 804 | args_r = '[%s]' % ', '.join(_type_repr(t) |
| 805 | for t in self.__args__) |
| 806 | r += '[%s, %s]' % (args_r, _type_repr(self.__result__)) |
| 807 | return r |
| 808 | |
| 809 | def __getitem__(self, parameters): |
| 810 | if self.__args__ is not None or self.__result__ is not None: |
| 811 | raise TypeError("This Callable type is already parameterized.") |
| 812 | if not isinstance(parameters, tuple) or len(parameters) != 2: |
| 813 | raise TypeError( |
| 814 | "Callable must be used as Callable[[arg, ...], result].") |
| 815 | args, result = parameters |
| 816 | return self.__class__(self.__name__, self.__bases__, |
| 817 | dict(self.__dict__), _root=True, |
| 818 | args=args, result=result) |
| 819 | |
| 820 | def __eq__(self, other): |
| 821 | if not isinstance(other, CallableMeta): |
| 822 | return NotImplemented |
| 823 | return (self.__args__ == other.__args__ and |
| 824 | self.__result__ == other.__result__) |
| 825 | |
| 826 | def __hash__(self): |
| 827 | return hash(self.__args__) ^ hash(self.__result__) |
| 828 | |
| 829 | def __instancecheck__(self, instance): |
| 830 | if not callable(instance): |
| 831 | return False |
| 832 | if self.__args__ is None and self.__result__ is None: |
| 833 | return True |
| 834 | assert self.__args__ is not None |
| 835 | assert self.__result__ is not None |
| 836 | my_args, my_result = self.__args__, self.__result__ |
| 837 | import inspect # TODO: Avoid this import. |
| 838 | # Would it be better to use Signature objects? |
| 839 | try: |
| 840 | (args, varargs, varkw, defaults, kwonlyargs, kwonlydefaults, |
| 841 | annotations) = inspect.getfullargspec(instance) |
| 842 | except TypeError: |
| 843 | return False # We can't find the signature. Give up. |
| 844 | msg = ("When testing isinstance(<callable>, Callable[...], " |
| 845 | "<calleble>'s annotations must be types.") |
| 846 | if my_args is not Ellipsis: |
| 847 | if kwonlyargs and (not kwonlydefaults or |
| 848 | len(kwonlydefaults) < len(kwonlyargs)): |
| 849 | return False |
| 850 | if isinstance(instance, types.MethodType): |
| 851 | # For methods, getfullargspec() includes self/cls, |
| 852 | # but it's not part of the call signature, so drop it. |
| 853 | del args[0] |
| 854 | min_call_args = len(args) |
| 855 | if defaults: |
| 856 | min_call_args -= len(defaults) |
| 857 | if varargs: |
| 858 | max_call_args = 999999999 |
| 859 | if len(args) < len(my_args): |
| 860 | args += [varargs] * (len(my_args) - len(args)) |
| 861 | else: |
| 862 | max_call_args = len(args) |
| 863 | if not min_call_args <= len(my_args) <= max_call_args: |
| 864 | return False |
| 865 | for my_arg_type, name in zip(my_args, args): |
| 866 | if name in annotations: |
| 867 | annot_type = _type_check(annotations[name], msg) |
| 868 | else: |
| 869 | annot_type = Any |
| 870 | if not issubclass(my_arg_type, annot_type): |
| 871 | return False |
| 872 | # TODO: If mutable type, check invariance? |
| 873 | if 'return' in annotations: |
| 874 | annot_return_type = _type_check(annotations['return'], msg) |
| 875 | # Note contravariance here! |
| 876 | if not issubclass(annot_return_type, my_result): |
| 877 | return False |
| 878 | # Can't find anything wrong... |
| 879 | return True |
| 880 | |
| 881 | def __subclasscheck__(self, cls): |
| 882 | if cls is Any: |
| 883 | return True |
| 884 | if not isinstance(cls, CallableMeta): |
| 885 | return super().__subclasscheck__(cls) |
| 886 | if self.__args__ is None and self.__result__ is None: |
| 887 | return True |
| 888 | # We're not doing covariance or contravariance -- this is *invariance*. |
| 889 | return self == cls |
| 890 | |
| 891 | |
| 892 | class Callable(Final, metaclass=CallableMeta, _root=True): |
| 893 | """Callable type; Callable[[int], str] is a function of (int) -> str. |
| 894 | |
| 895 | The subscription syntax must always be used with exactly two |
| 896 | values: the argument list and the return type. The argument list |
| 897 | must be a list of types; the return type must be a single type. |
| 898 | |
| 899 | There is no syntax to indicate optional or keyword arguments, |
| 900 | such function types are rarely used as callback types. |
| 901 | """ |
| 902 | |
| 903 | |
| 904 | def _gorg(a): |
| 905 | """Return the farthest origin of a generic class.""" |
| 906 | assert isinstance(a, GenericMeta) |
| 907 | while a.__origin__ is not None: |
| 908 | a = a.__origin__ |
| 909 | return a |
| 910 | |
| 911 | |
| 912 | def _geqv(a, b): |
| 913 | """Return whether two generic classes are equivalent. |
| 914 | |
| 915 | The intention is to consider generic class X and any of its |
| 916 | parameterized forms (X[T], X[int], etc.) as equivalent. |
| 917 | |
| 918 | However, X is not equivalent to a subclass of X. |
| 919 | |
| 920 | The relation is reflexive, symmetric and transitive. |
| 921 | """ |
| 922 | assert isinstance(a, GenericMeta) and isinstance(b, GenericMeta) |
| 923 | # Reduce each to its origin. |
| 924 | return _gorg(a) is _gorg(b) |
| 925 | |
| 926 | |
| 927 | class GenericMeta(TypingMeta, abc.ABCMeta): |
| 928 | """Metaclass for generic types.""" |
| 929 | |
| 930 | # TODO: Constrain more how Generic is used; only a few |
| 931 | # standard patterns should be allowed. |
| 932 | |
| 933 | # TODO: Use a more precise rule than matching __name__ to decide |
| 934 | # whether two classes are the same. Also, save the formal |
| 935 | # parameters. (These things are related! A solution lies in |
| 936 | # using origin.) |
| 937 | |
| 938 | __extra__ = None |
| 939 | |
| 940 | def __new__(cls, name, bases, namespace, |
| 941 | parameters=None, origin=None, extra=None): |
| 942 | if parameters is None: |
| 943 | # Extract parameters from direct base classes. Only |
| 944 | # direct bases are considered and only those that are |
| 945 | # themselves generic, and parameterized with type |
| 946 | # variables. Don't use bases like Any, Union, Tuple, |
| 947 | # Callable or type variables. |
| 948 | params = None |
| 949 | for base in bases: |
| 950 | if isinstance(base, TypingMeta): |
| 951 | if not isinstance(base, GenericMeta): |
| 952 | raise TypeError( |
| 953 | "You cannot inherit from magic class %s" % |
| 954 | repr(base)) |
| 955 | if base.__parameters__ is None: |
| 956 | continue # The base is unparameterized. |
| 957 | for bp in base.__parameters__: |
| 958 | if _has_type_var(bp) and not isinstance(bp, TypeVar): |
| 959 | raise TypeError( |
| 960 | "Cannot inherit from a generic class " |
| 961 | "parameterized with " |
| 962 | "non-type-variable %s" % bp) |
| 963 | if params is None: |
| 964 | params = [] |
| 965 | if bp not in params: |
| 966 | params.append(bp) |
| 967 | if params is not None: |
| 968 | parameters = tuple(params) |
| 969 | self = super().__new__(cls, name, bases, namespace, _root=True) |
| 970 | self.__parameters__ = parameters |
| 971 | if extra is not None: |
| 972 | self.__extra__ = extra |
| 973 | # Else __extra__ is inherited, eventually from the |
| 974 | # (meta-)class default above. |
| 975 | self.__origin__ = origin |
| 976 | return self |
| 977 | |
| 978 | def _has_type_var(self): |
| 979 | if self.__parameters__: |
| 980 | for t in self.__parameters__: |
| 981 | if _has_type_var(t): |
| 982 | return True |
| 983 | return False |
| 984 | |
| 985 | def __repr__(self): |
| 986 | r = super().__repr__() |
| 987 | if self.__parameters__ is not None: |
| 988 | r += '[%s]' % ( |
| 989 | ', '.join(_type_repr(p) for p in self.__parameters__)) |
| 990 | return r |
| 991 | |
| 992 | def __eq__(self, other): |
| 993 | if not isinstance(other, GenericMeta): |
| 994 | return NotImplemented |
| 995 | return (_geqv(self, other) and |
| 996 | self.__parameters__ == other.__parameters__) |
| 997 | |
| 998 | def __hash__(self): |
| 999 | return hash((self.__name__, self.__parameters__)) |
| 1000 | |
| 1001 | def __getitem__(self, params): |
| 1002 | if not isinstance(params, tuple): |
| 1003 | params = (params,) |
| 1004 | if not params: |
| 1005 | raise TypeError("Cannot have empty parameter list") |
| 1006 | msg = "Parameters to generic types must be types." |
| 1007 | params = tuple(_type_check(p, msg) for p in params) |
| 1008 | if self.__parameters__ is None: |
| 1009 | for p in params: |
| 1010 | if not isinstance(p, TypeVar): |
| 1011 | raise TypeError("Initial parameters must be " |
| 1012 | "type variables; got %s" % p) |
| 1013 | else: |
| 1014 | if len(params) != len(self.__parameters__): |
| 1015 | raise TypeError("Cannot change parameter count from %d to %d" % |
| 1016 | (len(self.__parameters__), len(params))) |
| 1017 | for new, old in zip(params, self.__parameters__): |
| 1018 | if isinstance(old, TypeVar): |
| 1019 | if not old.__constraints__: |
| 1020 | # Substituting for an unconstrained TypeVar is OK. |
| 1021 | continue |
| 1022 | if issubclass(new, Union[old.__constraints__]): |
| 1023 | # Specializing a constrained type variable is OK. |
| 1024 | continue |
| 1025 | if not issubclass(new, old): |
| 1026 | raise TypeError( |
| 1027 | "Cannot substitute %s for %s in %s" % |
| 1028 | (_type_repr(new), _type_repr(old), self)) |
| 1029 | |
| 1030 | return self.__class__(self.__name__, self.__bases__, |
| 1031 | dict(self.__dict__), |
| 1032 | parameters=params, |
| 1033 | origin=self, |
| 1034 | extra=self.__extra__) |
| 1035 | |
| 1036 | def __subclasscheck__(self, cls): |
| 1037 | if cls is Any: |
| 1038 | return True |
| 1039 | if isinstance(cls, GenericMeta): |
| 1040 | # For a class C(Generic[T]) where T is co-variant, |
| 1041 | # C[X] is a subclass of C[Y] iff X is a subclass of Y. |
| 1042 | origin = self.__origin__ |
| 1043 | if origin is not None and origin is cls.__origin__: |
| 1044 | assert len(self.__parameters__) == len(origin.__parameters__) |
| 1045 | assert len(cls.__parameters__) == len(origin.__parameters__) |
| 1046 | for p_self, p_cls, p_origin in zip(self.__parameters__, |
| 1047 | cls.__parameters__, |
| 1048 | origin.__parameters__): |
| 1049 | if isinstance(p_origin, TypeVar): |
| 1050 | if p_origin.__covariant__: |
| 1051 | # Covariant -- p_cls must be a subclass of p_self. |
| 1052 | if not issubclass(p_cls, p_self): |
| 1053 | break |
| 1054 | elif p_origin.__contravariant__: |
| 1055 | # Contravariant. I think it's the opposite. :-) |
| 1056 | if not issubclass(p_self, p_cls): |
| 1057 | break |
| 1058 | else: |
| 1059 | # Invariant -- p_cls and p_self must equal. |
| 1060 | if p_self != p_cls: |
| 1061 | break |
| 1062 | else: |
| 1063 | # If the origin's parameter is not a typevar, |
| 1064 | # insist on invariance. |
| 1065 | if p_self != p_cls: |
| 1066 | break |
| 1067 | else: |
| 1068 | return True |
| 1069 | # If we break out of the loop, the superclass gets a chance. |
| 1070 | if super().__subclasscheck__(cls): |
| 1071 | return True |
| 1072 | if self.__extra__ is None or isinstance(cls, GenericMeta): |
| 1073 | return False |
| 1074 | return issubclass(cls, self.__extra__) |
| 1075 | |
| 1076 | def __instancecheck__(self, obj): |
| 1077 | if super().__instancecheck__(obj): |
| 1078 | return True |
| 1079 | if self.__extra__ is None: |
| 1080 | return False |
| 1081 | return isinstance(obj, self.__extra__) |
| 1082 | |
| 1083 | |
| 1084 | class Generic(metaclass=GenericMeta): |
| 1085 | """Abstract base class for generic types. |
| 1086 | |
| 1087 | A generic type is typically declared by inheriting from an |
| 1088 | instantiation of this class with one or more type variables. |
| 1089 | For example, a generic mapping type might be defined as:: |
| 1090 | |
| 1091 | class Mapping(Generic[KT, VT]): |
| 1092 | def __getitem__(self, key: KT) -> VT: |
| 1093 | ... |
| 1094 | # Etc. |
| 1095 | |
| 1096 | This class can then be used as follows:: |
| 1097 | |
| 1098 | def lookup_name(mapping: Mapping, key: KT, default: VT) -> VT: |
| 1099 | try: |
| 1100 | return mapping[key] |
| 1101 | except KeyError: |
| 1102 | return default |
| 1103 | |
| 1104 | For clarity the type variables may be redefined, e.g.:: |
| 1105 | |
| 1106 | X = TypeVar('X') |
| 1107 | Y = TypeVar('Y') |
| 1108 | def lookup_name(mapping: Mapping[X, Y], key: X, default: Y) -> Y: |
| 1109 | # Same body as above. |
| 1110 | """ |
| 1111 | |
| 1112 | def __new__(cls, *args, **kwds): |
| 1113 | next_in_mro = object |
| 1114 | # Look for the last occurrence of Generic or Generic[...]. |
| 1115 | for i, c in enumerate(cls.__mro__[:-1]): |
| 1116 | if isinstance(c, GenericMeta) and _gorg(c) is Generic: |
| 1117 | next_in_mro = cls.__mro__[i+1] |
| 1118 | return next_in_mro.__new__(_gorg(cls)) |
| 1119 | |
| 1120 | |
| 1121 | def cast(typ, val): |
| 1122 | """Cast a value to a type. |
| 1123 | |
| 1124 | This returns the value unchanged. To the type checker this |
| 1125 | signals that the return value has the designated type, but at |
| 1126 | runtime we intentionally don't check anything (we want this |
| 1127 | to be as fast as possible). |
| 1128 | """ |
| 1129 | return val |
| 1130 | |
| 1131 | |
| 1132 | def _get_defaults(func): |
| 1133 | """Internal helper to extract the default arguments, by name.""" |
| 1134 | code = func.__code__ |
| 1135 | pos_count = code.co_argcount |
| 1136 | kw_count = code.co_kwonlyargcount |
| 1137 | arg_names = code.co_varnames |
| 1138 | kwarg_names = arg_names[pos_count:pos_count + kw_count] |
| 1139 | arg_names = arg_names[:pos_count] |
| 1140 | defaults = func.__defaults__ or () |
| 1141 | kwdefaults = func.__kwdefaults__ |
| 1142 | res = dict(kwdefaults) if kwdefaults else {} |
| 1143 | pos_offset = pos_count - len(defaults) |
| 1144 | for name, value in zip(arg_names[pos_offset:], defaults): |
| 1145 | assert name not in res |
| 1146 | res[name] = value |
| 1147 | return res |
| 1148 | |
| 1149 | |
| 1150 | def get_type_hints(obj, globalns=None, localns=None): |
| 1151 | """Return type hints for a function or method object. |
| 1152 | |
| 1153 | This is often the same as obj.__annotations__, but it handles |
| 1154 | forward references encoded as string literals, and if necessary |
| 1155 | adds Optional[t] if a default value equal to None is set. |
| 1156 | |
| 1157 | BEWARE -- the behavior of globalns and localns is counterintuitive |
| 1158 | (unless you are familiar with how eval() and exec() work). The |
| 1159 | search order is locals first, then globals. |
| 1160 | |
| 1161 | - If no dict arguments are passed, an attempt is made to use the |
| 1162 | globals from obj, and these are also used as the locals. If the |
| 1163 | object does not appear to have globals, an exception is raised. |
| 1164 | |
| 1165 | - If one dict argument is passed, it is used for both globals and |
| 1166 | locals. |
| 1167 | |
| 1168 | - If two dict arguments are passed, they specify globals and |
| 1169 | locals, respectively. |
| 1170 | """ |
| 1171 | if getattr(obj, '__no_type_check__', None): |
| 1172 | return {} |
| 1173 | if globalns is None: |
| 1174 | globalns = getattr(obj, '__globals__', {}) |
| 1175 | if localns is None: |
| 1176 | localns = globalns |
| 1177 | elif localns is None: |
| 1178 | localns = globalns |
| 1179 | defaults = _get_defaults(obj) |
| 1180 | hints = dict(obj.__annotations__) |
| 1181 | for name, value in hints.items(): |
| 1182 | if isinstance(value, str): |
| 1183 | value = _ForwardRef(value) |
| 1184 | value = _eval_type(value, globalns, localns) |
| 1185 | if name in defaults and defaults[name] is None: |
| 1186 | value = Optional[value] |
| 1187 | hints[name] = value |
| 1188 | return hints |
| 1189 | |
| 1190 | |
| 1191 | # TODO: Also support this as a class decorator. |
| 1192 | def no_type_check(arg): |
| 1193 | """Decorator to indicate that annotations are not type hints. |
| 1194 | |
| 1195 | The argument must be a class or function; if it is a class, it |
| 1196 | applies recursively to all methods defined in that class (but not |
| 1197 | to methods defined in its superclasses or subclasses). |
| 1198 | |
| 1199 | This mutates the function(s) in place. |
| 1200 | """ |
| 1201 | if isinstance(arg, type): |
| 1202 | for obj in arg.__dict__.values(): |
| 1203 | if isinstance(obj, types.FunctionType): |
| 1204 | obj.__no_type_check__ = True |
| 1205 | else: |
| 1206 | arg.__no_type_check__ = True |
| 1207 | return arg |
| 1208 | |
| 1209 | |
| 1210 | def no_type_check_decorator(decorator): |
| 1211 | """Decorator to give another decorator the @no_type_check effect. |
| 1212 | |
| 1213 | This wraps the decorator with something that wraps the decorated |
| 1214 | function in @no_type_check. |
| 1215 | """ |
| 1216 | |
| 1217 | @functools.wraps(decorator) |
| 1218 | def wrapped_decorator(*args, **kwds): |
| 1219 | func = decorator(*args, **kwds) |
| 1220 | func = no_type_check(func) |
| 1221 | return func |
| 1222 | |
| 1223 | return wrapped_decorator |
| 1224 | |
| 1225 | |
| 1226 | def overload(func): |
| 1227 | raise RuntimeError("Overloading is only supported in library stubs") |
| 1228 | |
| 1229 | |
| 1230 | class _ProtocolMeta(GenericMeta): |
| 1231 | """Internal metaclass for _Protocol. |
| 1232 | |
| 1233 | This exists so _Protocol classes can be generic without deriving |
| 1234 | from Generic. |
| 1235 | """ |
| 1236 | |
| 1237 | def __subclasscheck__(self, cls): |
| 1238 | if not self._is_protocol: |
| 1239 | # No structural checks since this isn't a protocol. |
| 1240 | return NotImplemented |
| 1241 | |
| 1242 | if self is _Protocol: |
| 1243 | # Every class is a subclass of the empty protocol. |
| 1244 | return True |
| 1245 | |
| 1246 | # Find all attributes defined in the protocol. |
| 1247 | attrs = self._get_protocol_attrs() |
| 1248 | |
| 1249 | for attr in attrs: |
| 1250 | if not any(attr in d.__dict__ for d in cls.__mro__): |
| 1251 | return False |
| 1252 | return True |
| 1253 | |
| 1254 | def _get_protocol_attrs(self): |
| 1255 | # Get all Protocol base classes. |
| 1256 | protocol_bases = [] |
| 1257 | for c in self.__mro__: |
| 1258 | if getattr(c, '_is_protocol', False) and c.__name__ != '_Protocol': |
| 1259 | protocol_bases.append(c) |
| 1260 | |
| 1261 | # Get attributes included in protocol. |
| 1262 | attrs = set() |
| 1263 | for base in protocol_bases: |
| 1264 | for attr in base.__dict__.keys(): |
| 1265 | # Include attributes not defined in any non-protocol bases. |
| 1266 | for c in self.__mro__: |
| 1267 | if (c is not base and attr in c.__dict__ and |
| 1268 | not getattr(c, '_is_protocol', False)): |
| 1269 | break |
| 1270 | else: |
| 1271 | if (not attr.startswith('_abc_') and |
| 1272 | attr != '__abstractmethods__' and |
| 1273 | attr != '_is_protocol' and |
| 1274 | attr != '__dict__' and |
| 1275 | attr != '_get_protocol_attrs' and |
| 1276 | attr != '__parameters__' and |
| 1277 | attr != '__origin__' and |
| 1278 | attr != '__module__'): |
| 1279 | attrs.add(attr) |
| 1280 | |
| 1281 | return attrs |
| 1282 | |
| 1283 | |
| 1284 | class _Protocol(metaclass=_ProtocolMeta): |
| 1285 | """Internal base class for protocol classes. |
| 1286 | |
| 1287 | This implements a simple-minded structural isinstance check |
| 1288 | (similar but more general than the one-offs in collections.abc |
| 1289 | such as Hashable). |
| 1290 | """ |
| 1291 | |
| 1292 | _is_protocol = True |
| 1293 | |
| 1294 | |
| 1295 | # Various ABCs mimicking those in collections.abc. |
| 1296 | # A few are simply re-exported for completeness. |
| 1297 | |
| 1298 | Hashable = collections_abc.Hashable # Not generic. |
| 1299 | |
| 1300 | |
| 1301 | class Iterable(Generic[T_co], extra=collections_abc.Iterable): |
| 1302 | pass |
| 1303 | |
| 1304 | |
| 1305 | class Iterator(Iterable[T_co], extra=collections_abc.Iterator): |
| 1306 | pass |
| 1307 | |
| 1308 | |
| 1309 | class SupportsInt(_Protocol): |
| 1310 | |
| 1311 | @abstractmethod |
| 1312 | def __int__(self) -> int: |
| 1313 | pass |
| 1314 | |
| 1315 | |
| 1316 | class SupportsFloat(_Protocol): |
| 1317 | |
| 1318 | @abstractmethod |
| 1319 | def __float__(self) -> float: |
| 1320 | pass |
| 1321 | |
| 1322 | |
| 1323 | class SupportsComplex(_Protocol): |
| 1324 | |
| 1325 | @abstractmethod |
| 1326 | def __complex__(self) -> complex: |
| 1327 | pass |
| 1328 | |
| 1329 | |
| 1330 | class SupportsBytes(_Protocol): |
| 1331 | |
| 1332 | @abstractmethod |
| 1333 | def __bytes__(self) -> bytes: |
| 1334 | pass |
| 1335 | |
| 1336 | |
| 1337 | class SupportsAbs(_Protocol[T]): |
| 1338 | |
| 1339 | @abstractmethod |
| 1340 | def __abs__(self) -> T: |
| 1341 | pass |
| 1342 | |
| 1343 | |
| 1344 | class SupportsRound(_Protocol[T]): |
| 1345 | |
| 1346 | @abstractmethod |
| 1347 | def __round__(self, ndigits: int = 0) -> T: |
| 1348 | pass |
| 1349 | |
| 1350 | |
| 1351 | class Reversible(_Protocol[T]): |
| 1352 | |
| 1353 | @abstractmethod |
| 1354 | def __reversed__(self) -> 'Iterator[T]': |
| 1355 | pass |
| 1356 | |
| 1357 | |
| 1358 | Sized = collections_abc.Sized # Not generic. |
| 1359 | |
| 1360 | |
| 1361 | class Container(Generic[T_co], extra=collections_abc.Container): |
| 1362 | pass |
| 1363 | |
| 1364 | |
| 1365 | # Callable was defined earlier. |
| 1366 | |
| 1367 | |
| 1368 | class AbstractSet(Sized, Iterable[T_co], Container[T_co], |
| 1369 | extra=collections_abc.Set): |
| 1370 | pass |
| 1371 | |
| 1372 | |
| 1373 | class MutableSet(AbstractSet[T], extra=collections_abc.MutableSet): |
| 1374 | pass |
| 1375 | |
| 1376 | |
| 1377 | class Mapping(Sized, Iterable[KT_co], Container[KT_co], Generic[KT_co, VT_co], |
| 1378 | extra=collections_abc.Mapping): |
| 1379 | pass |
| 1380 | |
| 1381 | |
| 1382 | class MutableMapping(Mapping[KT, VT], extra=collections_abc.MutableMapping): |
| 1383 | pass |
| 1384 | |
| 1385 | |
| 1386 | class Sequence(Sized, Iterable[T_co], Container[T_co], |
| 1387 | extra=collections_abc.Sequence): |
| 1388 | pass |
| 1389 | |
| 1390 | |
| 1391 | class MutableSequence(Sequence[T], extra=collections_abc.MutableSequence): |
| 1392 | pass |
| 1393 | |
| 1394 | |
| 1395 | class ByteString(Sequence[int], extra=collections_abc.ByteString): |
| 1396 | pass |
| 1397 | |
| 1398 | |
| 1399 | ByteString.register(type(memoryview(b''))) |
| 1400 | |
| 1401 | |
| 1402 | class _ListMeta(GenericMeta): |
| 1403 | |
| 1404 | def __instancecheck__(self, obj): |
| 1405 | if not super().__instancecheck__(obj): |
| 1406 | return False |
| 1407 | itemtype = self.__parameters__[0] |
| 1408 | for x in obj: |
| 1409 | if not isinstance(x, itemtype): |
| 1410 | return False |
| 1411 | return True |
| 1412 | |
| 1413 | |
| 1414 | class List(list, MutableSequence[T], metaclass=_ListMeta): |
| 1415 | |
| 1416 | def __new__(cls, *args, **kwds): |
| 1417 | if _geqv(cls, List): |
| 1418 | raise TypeError("Type List cannot be instantiated; " |
| 1419 | "use list() instead") |
| 1420 | return list.__new__(cls, *args, **kwds) |
| 1421 | |
| 1422 | |
| 1423 | class _SetMeta(GenericMeta): |
| 1424 | |
| 1425 | def __instancecheck__(self, obj): |
| 1426 | if not super().__instancecheck__(obj): |
| 1427 | return False |
| 1428 | itemtype = self.__parameters__[0] |
| 1429 | for x in obj: |
| 1430 | if not isinstance(x, itemtype): |
| 1431 | return False |
| 1432 | return True |
| 1433 | |
| 1434 | |
| 1435 | class Set(set, MutableSet[T], metaclass=_SetMeta): |
| 1436 | |
| 1437 | def __new__(cls, *args, **kwds): |
| 1438 | if _geqv(cls, Set): |
| 1439 | raise TypeError("Type Set cannot be instantiated; " |
| 1440 | "use set() instead") |
| 1441 | return set.__new__(cls, *args, **kwds) |
| 1442 | |
| 1443 | |
| 1444 | class _FrozenSetMeta(_SetMeta): |
| 1445 | """This metaclass ensures set is not a subclass of FrozenSet. |
| 1446 | |
| 1447 | Without this metaclass, set would be considered a subclass of |
| 1448 | FrozenSet, because FrozenSet.__extra__ is collections.abc.Set, and |
| 1449 | set is a subclass of that. |
| 1450 | """ |
| 1451 | |
| 1452 | def __subclasscheck__(self, cls): |
| 1453 | if issubclass(cls, Set): |
| 1454 | return False |
| 1455 | return super().__subclasscheck__(cls) |
| 1456 | |
| 1457 | def __instancecheck__(self, obj): |
| 1458 | if issubclass(obj.__class__, Set): |
| 1459 | return False |
| 1460 | return super().__instancecheck__(obj) |
| 1461 | |
| 1462 | |
| 1463 | class FrozenSet(frozenset, AbstractSet[T_co], metaclass=_FrozenSetMeta): |
| 1464 | |
| 1465 | def __new__(cls, *args, **kwds): |
| 1466 | if _geqv(cls, FrozenSet): |
| 1467 | raise TypeError("Type FrozenSet cannot be instantiated; " |
| 1468 | "use frozenset() instead") |
| 1469 | return frozenset.__new__(cls, *args, **kwds) |
| 1470 | |
| 1471 | |
| 1472 | class MappingView(Sized, Iterable[T_co], extra=collections_abc.MappingView): |
| 1473 | pass |
| 1474 | |
| 1475 | |
| 1476 | class KeysView(MappingView[KT_co], AbstractSet[KT_co], |
| 1477 | extra=collections_abc.KeysView): |
| 1478 | pass |
| 1479 | |
| 1480 | |
| 1481 | # TODO: Enable Set[Tuple[KT_co, VT_co]] instead of Generic[KT_co, VT_co]. |
| 1482 | class ItemsView(MappingView, Generic[KT_co, VT_co], |
| 1483 | extra=collections_abc.ItemsView): |
| 1484 | pass |
| 1485 | |
| 1486 | |
| 1487 | class ValuesView(MappingView[VT_co], extra=collections_abc.ValuesView): |
| 1488 | pass |
| 1489 | |
| 1490 | |
| 1491 | class _DictMeta(GenericMeta): |
| 1492 | |
| 1493 | def __instancecheck__(self, obj): |
| 1494 | if not super().__instancecheck__(obj): |
| 1495 | return False |
| 1496 | keytype, valuetype = self.__parameters__ |
| 1497 | for key, value in obj.items(): |
| 1498 | if not (isinstance(key, keytype) and |
| 1499 | isinstance(value, valuetype)): |
| 1500 | return False |
| 1501 | return True |
| 1502 | |
| 1503 | |
| 1504 | class Dict(dict, MutableMapping[KT, VT], metaclass=_DictMeta): |
| 1505 | |
| 1506 | def __new__(cls, *args, **kwds): |
| 1507 | if _geqv(cls, Dict): |
| 1508 | raise TypeError("Type Dict cannot be instantiated; " |
| 1509 | "use dict() instead") |
| 1510 | return dict.__new__(cls, *args, **kwds) |
| 1511 | |
| 1512 | |
| 1513 | # Determine what base class to use for Generator. |
| 1514 | if hasattr(collections_abc, 'Generator'): |
| 1515 | # Sufficiently recent versions of 3.5 have a Generator ABC. |
| 1516 | _G_base = collections_abc.Generator |
| 1517 | else: |
| 1518 | # Fall back on the exact type. |
| 1519 | _G_base = types.GeneratorType |
| 1520 | |
| 1521 | |
| 1522 | class Generator(Iterator[T_co], Generic[T_co, T_contra, V_co], |
| 1523 | extra=_G_base): |
| 1524 | |
| 1525 | def __new__(cls, *args, **kwds): |
| 1526 | if _geqv(cls, Generator): |
| 1527 | raise TypeError("Type Generator cannot be instantiated; " |
| 1528 | "create a subclass instead") |
| 1529 | return super().__new__(cls, *args, **kwds) |
| 1530 | |
| 1531 | |
| 1532 | def NamedTuple(typename, fields): |
| 1533 | """Typed version of namedtuple. |
| 1534 | |
| 1535 | Usage:: |
| 1536 | |
| 1537 | Employee = typing.NamedTuple('Employee', [('name', str), 'id', int)]) |
| 1538 | |
| 1539 | This is equivalent to:: |
| 1540 | |
| 1541 | Employee = collections.namedtuple('Employee', ['name', 'id']) |
| 1542 | |
| 1543 | The resulting class has one extra attribute: _field_types, |
| 1544 | giving a dict mapping field names to types. (The field names |
| 1545 | are in the _fields attribute, which is part of the namedtuple |
| 1546 | API.) |
| 1547 | """ |
| 1548 | fields = [(n, t) for n, t in fields] |
| 1549 | cls = collections.namedtuple(typename, [n for n, t in fields]) |
| 1550 | cls._field_types = dict(fields) |
| 1551 | return cls |
| 1552 | |
| 1553 | |
| 1554 | class IO(Generic[AnyStr]): |
| 1555 | """Generic base class for TextIO and BinaryIO. |
| 1556 | |
| 1557 | This is an abstract, generic version of the return of open(). |
| 1558 | |
| 1559 | NOTE: This does not distinguish between the different possible |
| 1560 | classes (text vs. binary, read vs. write vs. read/write, |
| 1561 | append-only, unbuffered). The TextIO and BinaryIO subclasses |
| 1562 | below capture the distinctions between text vs. binary, which is |
| 1563 | pervasive in the interface; however we currently do not offer a |
| 1564 | way to track the other distinctions in the type system. |
| 1565 | """ |
| 1566 | |
| 1567 | @abstractproperty |
| 1568 | def mode(self) -> str: |
| 1569 | pass |
| 1570 | |
| 1571 | @abstractproperty |
| 1572 | def name(self) -> str: |
| 1573 | pass |
| 1574 | |
| 1575 | @abstractmethod |
| 1576 | def close(self) -> None: |
| 1577 | pass |
| 1578 | |
| 1579 | @abstractmethod |
| 1580 | def closed(self) -> bool: |
| 1581 | pass |
| 1582 | |
| 1583 | @abstractmethod |
| 1584 | def fileno(self) -> int: |
| 1585 | pass |
| 1586 | |
| 1587 | @abstractmethod |
| 1588 | def flush(self) -> None: |
| 1589 | pass |
| 1590 | |
| 1591 | @abstractmethod |
| 1592 | def isatty(self) -> bool: |
| 1593 | pass |
| 1594 | |
| 1595 | @abstractmethod |
| 1596 | def read(self, n: int = -1) -> AnyStr: |
| 1597 | pass |
| 1598 | |
| 1599 | @abstractmethod |
| 1600 | def readable(self) -> bool: |
| 1601 | pass |
| 1602 | |
| 1603 | @abstractmethod |
| 1604 | def readline(self, limit: int = -1) -> AnyStr: |
| 1605 | pass |
| 1606 | |
| 1607 | @abstractmethod |
| 1608 | def readlines(self, hint: int = -1) -> List[AnyStr]: |
| 1609 | pass |
| 1610 | |
| 1611 | @abstractmethod |
| 1612 | def seek(self, offset: int, whence: int = 0) -> int: |
| 1613 | pass |
| 1614 | |
| 1615 | @abstractmethod |
| 1616 | def seekable(self) -> bool: |
| 1617 | pass |
| 1618 | |
| 1619 | @abstractmethod |
| 1620 | def tell(self) -> int: |
| 1621 | pass |
| 1622 | |
| 1623 | @abstractmethod |
| 1624 | def truncate(self, size: int = None) -> int: |
| 1625 | pass |
| 1626 | |
| 1627 | @abstractmethod |
| 1628 | def writable(self) -> bool: |
| 1629 | pass |
| 1630 | |
| 1631 | @abstractmethod |
| 1632 | def write(self, s: AnyStr) -> int: |
| 1633 | pass |
| 1634 | |
| 1635 | @abstractmethod |
| 1636 | def writelines(self, lines: List[AnyStr]) -> None: |
| 1637 | pass |
| 1638 | |
| 1639 | @abstractmethod |
| 1640 | def __enter__(self) -> 'IO[AnyStr]': |
| 1641 | pass |
| 1642 | |
| 1643 | @abstractmethod |
| 1644 | def __exit__(self, type, value, traceback) -> None: |
| 1645 | pass |
| 1646 | |
| 1647 | |
| 1648 | class BinaryIO(IO[bytes]): |
| 1649 | """Typed version of the return of open() in binary mode.""" |
| 1650 | |
| 1651 | @abstractmethod |
| 1652 | def write(self, s: Union[bytes, bytearray]) -> int: |
| 1653 | pass |
| 1654 | |
| 1655 | @abstractmethod |
| 1656 | def __enter__(self) -> 'BinaryIO': |
| 1657 | pass |
| 1658 | |
| 1659 | |
| 1660 | class TextIO(IO[str]): |
| 1661 | """Typed version of the return of open() in text mode.""" |
| 1662 | |
| 1663 | @abstractproperty |
| 1664 | def buffer(self) -> BinaryIO: |
| 1665 | pass |
| 1666 | |
| 1667 | @abstractproperty |
| 1668 | def encoding(self) -> str: |
| 1669 | pass |
| 1670 | |
| 1671 | @abstractproperty |
| 1672 | def errors(self) -> str: |
| 1673 | pass |
| 1674 | |
| 1675 | @abstractproperty |
| 1676 | def line_buffering(self) -> bool: |
| 1677 | pass |
| 1678 | |
| 1679 | @abstractproperty |
| 1680 | def newlines(self) -> Any: |
| 1681 | pass |
| 1682 | |
| 1683 | @abstractmethod |
| 1684 | def __enter__(self) -> 'TextIO': |
| 1685 | pass |
| 1686 | |
| 1687 | |
| 1688 | class io: |
| 1689 | """Wrapper namespace for IO generic classes.""" |
| 1690 | |
| 1691 | __all__ = ['IO', 'TextIO', 'BinaryIO'] |
| 1692 | IO = IO |
| 1693 | TextIO = TextIO |
| 1694 | BinaryIO = BinaryIO |
| 1695 | |
| 1696 | io.__name__ = __name__ + '.io' |
| 1697 | sys.modules[io.__name__] = io |
| 1698 | |
| 1699 | |
| 1700 | Pattern = _TypeAlias('Pattern', AnyStr, type(stdlib_re.compile('')), |
| 1701 | lambda p: p.pattern) |
| 1702 | Match = _TypeAlias('Match', AnyStr, type(stdlib_re.match('', '')), |
| 1703 | lambda m: m.re.pattern) |
| 1704 | |
| 1705 | |
| 1706 | class re: |
| 1707 | """Wrapper namespace for re type aliases.""" |
| 1708 | |
| 1709 | __all__ = ['Pattern', 'Match'] |
| 1710 | Pattern = Pattern |
| 1711 | Match = Match |
| 1712 | |
| 1713 | re.__name__ = __name__ + '.re' |
| 1714 | sys.modules[re.__name__] = re |