| # TODO nits: | 
 | # Get rid of asserts that are the caller's fault. | 
 | # Docstrings (e.g. ABCs). | 
 |  | 
 | import abc | 
 | from abc import abstractmethod, abstractproperty | 
 | import collections | 
 | import functools | 
 | import re as stdlib_re  # Avoid confusion with the re we export. | 
 | import sys | 
 | import types | 
 | try: | 
 |     import collections.abc as collections_abc | 
 | except ImportError: | 
 |     import collections as collections_abc  # Fallback for PY3.2. | 
 |  | 
 |  | 
 | # Please keep __all__ alphabetized within each category. | 
 | __all__ = [ | 
 |     # Super-special typing primitives. | 
 |     'Any', | 
 |     'Callable', | 
 |     'Generic', | 
 |     'Optional', | 
 |     'TypeVar', | 
 |     'Union', | 
 |     'Tuple', | 
 |  | 
 |     # ABCs (from collections.abc). | 
 |     'AbstractSet',  # collections.abc.Set. | 
 |     'Awaitable', | 
 |     'AsyncIterator', | 
 |     'AsyncIterable', | 
 |     'ByteString', | 
 |     'Container', | 
 |     'Hashable', | 
 |     'ItemsView', | 
 |     'Iterable', | 
 |     'Iterator', | 
 |     'KeysView', | 
 |     'Mapping', | 
 |     'MappingView', | 
 |     'MutableMapping', | 
 |     'MutableSequence', | 
 |     'MutableSet', | 
 |     'Sequence', | 
 |     'Sized', | 
 |     'ValuesView', | 
 |  | 
 |     # Structural checks, a.k.a. protocols. | 
 |     'Reversible', | 
 |     'SupportsAbs', | 
 |     'SupportsFloat', | 
 |     'SupportsInt', | 
 |     'SupportsRound', | 
 |  | 
 |     # Concrete collection types. | 
 |     'Dict', | 
 |     'List', | 
 |     'Set', | 
 |     'NamedTuple',  # Not really a type. | 
 |     'Generator', | 
 |  | 
 |     # One-off things. | 
 |     'AnyStr', | 
 |     'cast', | 
 |     'get_type_hints', | 
 |     'no_type_check', | 
 |     'no_type_check_decorator', | 
 |     'overload', | 
 |  | 
 |     # Submodules. | 
 |     'io', | 
 |     're', | 
 | ] | 
 |  | 
 |  | 
 | def _qualname(x): | 
 |     if sys.version_info[:2] >= (3, 3): | 
 |         return x.__qualname__ | 
 |     else: | 
 |         # Fall back to just name. | 
 |         return x.__name__ | 
 |  | 
 |  | 
 | class TypingMeta(type): | 
 |     """Metaclass for every type defined below. | 
 |  | 
 |     This overrides __new__() to require an extra keyword parameter | 
 |     '_root', which serves as a guard against naive subclassing of the | 
 |     typing classes.  Any legitimate class defined using a metaclass | 
 |     derived from TypingMeta (including internal subclasses created by | 
 |     e.g.  Union[X, Y]) must pass _root=True. | 
 |  | 
 |     This also defines a dummy constructor (all the work is done in | 
 |     __new__) and a nicer repr(). | 
 |     """ | 
 |  | 
 |     _is_protocol = False | 
 |  | 
 |     def __new__(cls, name, bases, namespace, *, _root=False): | 
 |         if not _root: | 
 |             raise TypeError("Cannot subclass %s" % | 
 |                             (', '.join(map(_type_repr, bases)) or '()')) | 
 |         return super().__new__(cls, name, bases, namespace) | 
 |  | 
 |     def __init__(self, *args, **kwds): | 
 |         pass | 
 |  | 
 |     def _eval_type(self, globalns, localns): | 
 |         """Override this in subclasses to interpret forward references. | 
 |  | 
 |         For example, Union['C'] is internally stored as | 
 |         Union[_ForwardRef('C')], which should evaluate to _Union[C], | 
 |         where C is an object found in globalns or localns (searching | 
 |         localns first, of course). | 
 |         """ | 
 |         return self | 
 |  | 
 |     def _has_type_var(self): | 
 |         return False | 
 |  | 
 |     def __repr__(self): | 
 |         return '%s.%s' % (self.__module__, _qualname(self)) | 
 |  | 
 |  | 
 | class Final: | 
 |     """Mix-in class to prevent instantiation.""" | 
 |  | 
 |     __slots__ = () | 
 |  | 
 |     def __new__(self, *args, **kwds): | 
 |         raise TypeError("Cannot instantiate %r" % self.__class__) | 
 |  | 
 |  | 
 | class _ForwardRef(TypingMeta): | 
 |     """Wrapper to hold a forward reference.""" | 
 |  | 
 |     def __new__(cls, arg): | 
 |         if not isinstance(arg, str): | 
 |             raise TypeError('ForwardRef must be a string -- got %r' % (arg,)) | 
 |         try: | 
 |             code = compile(arg, '<string>', 'eval') | 
 |         except SyntaxError: | 
 |             raise SyntaxError('ForwardRef must be an expression -- got %r' % | 
 |                               (arg,)) | 
 |         self = super().__new__(cls, arg, (), {}, _root=True) | 
 |         self.__forward_arg__ = arg | 
 |         self.__forward_code__ = code | 
 |         self.__forward_evaluated__ = False | 
 |         self.__forward_value__ = None | 
 |         typing_globals = globals() | 
 |         frame = sys._getframe(1) | 
 |         while frame is not None and frame.f_globals is typing_globals: | 
 |             frame = frame.f_back | 
 |         assert frame is not None | 
 |         self.__forward_frame__ = frame | 
 |         return self | 
 |  | 
 |     def _eval_type(self, globalns, localns): | 
 |         if not isinstance(localns, dict): | 
 |             raise TypeError('ForwardRef localns must be a dict -- got %r' % | 
 |                             (localns,)) | 
 |         if not isinstance(globalns, dict): | 
 |             raise TypeError('ForwardRef globalns must be a dict -- got %r' % | 
 |                             (globalns,)) | 
 |         if not self.__forward_evaluated__: | 
 |             if globalns is None and localns is None: | 
 |                 globalns = localns = {} | 
 |             elif globalns is None: | 
 |                 globalns = localns | 
 |             elif localns is None: | 
 |                 localns = globalns | 
 |             self.__forward_value__ = _type_check( | 
 |                 eval(self.__forward_code__, globalns, localns), | 
 |                 "Forward references must evaluate to types.") | 
 |             self.__forward_evaluated__ = True | 
 |         return self.__forward_value__ | 
 |  | 
 |     def __instancecheck__(self, obj): | 
 |         raise TypeError("Forward references cannot be used with isinstance().") | 
 |  | 
 |     def __subclasscheck__(self, cls): | 
 |         if not self.__forward_evaluated__: | 
 |             globalns = self.__forward_frame__.f_globals | 
 |             localns = self.__forward_frame__.f_locals | 
 |             try: | 
 |                 self._eval_type(globalns, localns) | 
 |             except NameError: | 
 |                 return False  # Too early. | 
 |         return issubclass(cls, self.__forward_value__) | 
 |  | 
 |     def __repr__(self): | 
 |         return '_ForwardRef(%r)' % (self.__forward_arg__,) | 
 |  | 
 |  | 
 | class _TypeAlias: | 
 |     """Internal helper class for defining generic variants of concrete types. | 
 |  | 
 |     Note that this is not a type; let's call it a pseudo-type.  It can | 
 |     be used in instance and subclass checks, e.g. isinstance(m, Match) | 
 |     or issubclass(type(m), Match).  However, it cannot be itself the | 
 |     target of an issubclass() call; e.g. issubclass(Match, C) (for | 
 |     some arbitrary class C) raises TypeError rather than returning | 
 |     False. | 
 |     """ | 
 |  | 
 |     __slots__ = ('name', 'type_var', 'impl_type', 'type_checker') | 
 |  | 
 |     def __new__(cls, *args, **kwds): | 
 |         """Constructor. | 
 |  | 
 |         This only exists to give a better error message in case | 
 |         someone tries to subclass a type alias (not a good idea). | 
 |         """ | 
 |         if (len(args) == 3 and | 
 |             isinstance(args[0], str) and | 
 |             isinstance(args[1], tuple)): | 
 |             # Close enough. | 
 |             raise TypeError("A type alias cannot be subclassed") | 
 |         return object.__new__(cls) | 
 |  | 
 |     def __init__(self, name, type_var, impl_type, type_checker): | 
 |         """Initializer. | 
 |  | 
 |         Args: | 
 |             name: The name, e.g. 'Pattern'. | 
 |             type_var: The type parameter, e.g. AnyStr, or the | 
 |                 specific type, e.g. str. | 
 |             impl_type: The implementation type. | 
 |             type_checker: Function that takes an impl_type instance. | 
 |                 and returns a value that should be a type_var instance. | 
 |         """ | 
 |         assert isinstance(name, str), repr(name) | 
 |         assert isinstance(type_var, type), repr(type_var) | 
 |         assert isinstance(impl_type, type), repr(impl_type) | 
 |         assert not isinstance(impl_type, TypingMeta), repr(impl_type) | 
 |         self.name = name | 
 |         self.type_var = type_var | 
 |         self.impl_type = impl_type | 
 |         self.type_checker = type_checker | 
 |  | 
 |     def __repr__(self): | 
 |         return "%s[%s]" % (self.name, _type_repr(self.type_var)) | 
 |  | 
 |     def __getitem__(self, parameter): | 
 |         assert isinstance(parameter, type), repr(parameter) | 
 |         if not isinstance(self.type_var, TypeVar): | 
 |             raise TypeError("%s cannot be further parameterized." % self) | 
 |         if self.type_var.__constraints__: | 
 |             if not issubclass(parameter, Union[self.type_var.__constraints__]): | 
 |                 raise TypeError("%s is not a valid substitution for %s." % | 
 |                                 (parameter, self.type_var)) | 
 |         return self.__class__(self.name, parameter, | 
 |                               self.impl_type, self.type_checker) | 
 |  | 
 |     def __instancecheck__(self, obj): | 
 |         raise TypeError("Type aliases cannot be used with isinstance().") | 
 |  | 
 |     def __subclasscheck__(self, cls): | 
 |         if cls is Any: | 
 |             return True | 
 |         if isinstance(cls, _TypeAlias): | 
 |             # Covariance.  For now, we compare by name. | 
 |             return (cls.name == self.name and | 
 |                     issubclass(cls.type_var, self.type_var)) | 
 |         else: | 
 |             # Note that this is too lenient, because the | 
 |             # implementation type doesn't carry information about | 
 |             # whether it is about bytes or str (for example). | 
 |             return issubclass(cls, self.impl_type) | 
 |  | 
 |  | 
 | def _has_type_var(t): | 
 |     return t is not None and isinstance(t, TypingMeta) and t._has_type_var() | 
 |  | 
 |  | 
 | def _eval_type(t, globalns, localns): | 
 |     if isinstance(t, TypingMeta): | 
 |         return t._eval_type(globalns, localns) | 
 |     else: | 
 |         return t | 
 |  | 
 |  | 
 | def _type_check(arg, msg): | 
 |     """Check that the argument is a type, and return it. | 
 |  | 
 |     As a special case, accept None and return type(None) instead. | 
 |     Also, _TypeAlias instances (e.g. Match, Pattern) are acceptable. | 
 |  | 
 |     The msg argument is a human-readable error message, e.g. | 
 |  | 
 |         "Union[arg, ...]: arg should be a type." | 
 |  | 
 |     We append the repr() of the actual value (truncated to 100 chars). | 
 |     """ | 
 |     if arg is None: | 
 |         return type(None) | 
 |     if isinstance(arg, str): | 
 |         arg = _ForwardRef(arg) | 
 |     if not isinstance(arg, (type, _TypeAlias)): | 
 |         raise TypeError(msg + " Got %.100r." % (arg,)) | 
 |     return arg | 
 |  | 
 |  | 
 | def _type_repr(obj): | 
 |     """Return the repr() of an object, special-casing types. | 
 |  | 
 |     If obj is a type, we return a shorter version than the default | 
 |     type.__repr__, based on the module and qualified name, which is | 
 |     typically enough to uniquely identify a type.  For everything | 
 |     else, we fall back on repr(obj). | 
 |     """ | 
 |     if isinstance(obj, type) and not isinstance(obj, TypingMeta): | 
 |         if obj.__module__ == 'builtins': | 
 |             return _qualname(obj) | 
 |         else: | 
 |             return '%s.%s' % (obj.__module__, _qualname(obj)) | 
 |     else: | 
 |         return repr(obj) | 
 |  | 
 |  | 
 | class AnyMeta(TypingMeta): | 
 |     """Metaclass for Any.""" | 
 |  | 
 |     def __new__(cls, name, bases, namespace, _root=False): | 
 |         self = super().__new__(cls, name, bases, namespace, _root=_root) | 
 |         return self | 
 |  | 
 |     def __instancecheck__(self, obj): | 
 |         raise TypeError("Any cannot be used with isinstance().") | 
 |  | 
 |     def __subclasscheck__(self, cls): | 
 |         if not isinstance(cls, type): | 
 |             return super().__subclasscheck__(cls)  # To TypeError. | 
 |         return True | 
 |  | 
 |  | 
 | class Any(Final, metaclass=AnyMeta, _root=True): | 
 |     """Special type indicating an unconstrained type. | 
 |  | 
 |     - Any object is an instance of Any. | 
 |     - Any class is a subclass of Any. | 
 |     - As a special case, Any and object are subclasses of each other. | 
 |     """ | 
 |  | 
 |     __slots__ = () | 
 |  | 
 |  | 
 | class TypeVar(TypingMeta, metaclass=TypingMeta, _root=True): | 
 |     """Type variable. | 
 |  | 
 |     Usage:: | 
 |  | 
 |       T = TypeVar('T')  # Can be anything | 
 |       A = TypeVar('A', str, bytes)  # Must be str or bytes | 
 |  | 
 |     Type variables exist primarily for the benefit of static type | 
 |     checkers.  They serve as the parameters for generic types as well | 
 |     as for generic function definitions.  See class Generic for more | 
 |     information on generic types.  Generic functions work as follows: | 
 |  | 
 |       def repeat(x: T, n: int) -> Sequence[T]: | 
 |           '''Return a list containing n references to x.''' | 
 |           return [x]*n | 
 |  | 
 |       def longest(x: A, y: A) -> A: | 
 |           '''Return the longest of two strings.''' | 
 |           return x if len(x) >= len(y) else y | 
 |  | 
 |     The latter example's signature is essentially the overloading | 
 |     of (str, str) -> str and (bytes, bytes) -> bytes.  Also note | 
 |     that if the arguments are instances of some subclass of str, | 
 |     the return type is still plain str. | 
 |  | 
 |     At runtime, isinstance(x, T) will raise TypeError.  However, | 
 |     issubclass(C, T) is true for any class C, and issubclass(str, A) | 
 |     and issubclass(bytes, A) are true, and issubclass(int, A) is | 
 |     false. | 
 |  | 
 |     Type variables may be marked covariant or contravariant by passing | 
 |     covariant=True or contravariant=True.  See PEP 484 for more | 
 |     details.  By default type variables are invariant. | 
 |  | 
 |     Type variables can be introspected. e.g.: | 
 |  | 
 |       T.__name__ == 'T' | 
 |       T.__constraints__ == () | 
 |       T.__covariant__ == False | 
 |       T.__contravariant__ = False | 
 |       A.__constraints__ == (str, bytes) | 
 |     """ | 
 |  | 
 |     def __new__(cls, name, *constraints, bound=None, | 
 |                 covariant=False, contravariant=False): | 
 |         self = super().__new__(cls, name, (Final,), {}, _root=True) | 
 |         if covariant and contravariant: | 
 |             raise ValueError("Bivariant type variables are not supported.") | 
 |         self.__covariant__ = bool(covariant) | 
 |         self.__contravariant__ = bool(contravariant) | 
 |         if constraints and bound is not None: | 
 |             raise TypeError("Constraints cannot be combined with bound=...") | 
 |         if constraints and len(constraints) == 1: | 
 |             raise TypeError("A single constraint is not allowed") | 
 |         msg = "TypeVar(name, constraint, ...): constraints must be types." | 
 |         self.__constraints__ = tuple(_type_check(t, msg) for t in constraints) | 
 |         if bound: | 
 |             self.__bound__ = _type_check(bound, "Bound must be a type.") | 
 |         else: | 
 |             self.__bound__ = None | 
 |         return self | 
 |  | 
 |     def _has_type_var(self): | 
 |         return True | 
 |  | 
 |     def __repr__(self): | 
 |         if self.__covariant__: | 
 |             prefix = '+' | 
 |         elif self.__contravariant__: | 
 |             prefix = '-' | 
 |         else: | 
 |             prefix = '~' | 
 |         return prefix + self.__name__ | 
 |  | 
 |     def __instancecheck__(self, instance): | 
 |         raise TypeError("Type variables cannot be used with isinstance().") | 
 |  | 
 |     def __subclasscheck__(self, cls): | 
 |         # TODO: Make this raise TypeError too? | 
 |         if cls is self: | 
 |             return True | 
 |         if cls is Any: | 
 |             return True | 
 |         if self.__bound__ is not None: | 
 |             return issubclass(cls, self.__bound__) | 
 |         if self.__constraints__: | 
 |             return any(issubclass(cls, c) for c in self.__constraints__) | 
 |         return True | 
 |  | 
 |  | 
 | # Some unconstrained type variables.  These are used by the container types. | 
 | T = TypeVar('T')  # Any type. | 
 | KT = TypeVar('KT')  # Key type. | 
 | VT = TypeVar('VT')  # Value type. | 
 | T_co = TypeVar('T_co', covariant=True)  # Any type covariant containers. | 
 | V_co = TypeVar('V_co', covariant=True)  # Any type covariant containers. | 
 | VT_co = TypeVar('VT_co', covariant=True)  # Value type covariant containers. | 
 | T_contra = TypeVar('T_contra', contravariant=True)  # Ditto contravariant. | 
 |  | 
 | # A useful type variable with constraints.  This represents string types. | 
 | # TODO: What about bytearray, memoryview? | 
 | AnyStr = TypeVar('AnyStr', bytes, str) | 
 |  | 
 |  | 
 | class UnionMeta(TypingMeta): | 
 |     """Metaclass for Union.""" | 
 |  | 
 |     def __new__(cls, name, bases, namespace, parameters=None, _root=False): | 
 |         if parameters is None: | 
 |             return super().__new__(cls, name, bases, namespace, _root=_root) | 
 |         if not isinstance(parameters, tuple): | 
 |             raise TypeError("Expected parameters=<tuple>") | 
 |         # Flatten out Union[Union[...], ...] and type-check non-Union args. | 
 |         params = [] | 
 |         msg = "Union[arg, ...]: each arg must be a type." | 
 |         for p in parameters: | 
 |             if isinstance(p, UnionMeta): | 
 |                 params.extend(p.__union_params__) | 
 |             else: | 
 |                 params.append(_type_check(p, msg)) | 
 |         # Weed out strict duplicates, preserving the first of each occurrence. | 
 |         all_params = set(params) | 
 |         if len(all_params) < len(params): | 
 |             new_params = [] | 
 |             for t in params: | 
 |                 if t in all_params: | 
 |                     new_params.append(t) | 
 |                     all_params.remove(t) | 
 |             params = new_params | 
 |             assert not all_params, all_params | 
 |         # Weed out subclasses. | 
 |         # E.g. Union[int, Employee, Manager] == Union[int, Employee]. | 
 |         # If Any or object is present it will be the sole survivor. | 
 |         # If both Any and object are present, Any wins. | 
 |         # Never discard type variables, except against Any. | 
 |         # (In particular, Union[str, AnyStr] != AnyStr.) | 
 |         all_params = set(params) | 
 |         for t1 in params: | 
 |             if t1 is Any: | 
 |                 return Any | 
 |             if isinstance(t1, TypeVar): | 
 |                 continue | 
 |             if isinstance(t1, _TypeAlias): | 
 |                 # _TypeAlias is not a real class. | 
 |                 continue | 
 |             if any(issubclass(t1, t2) | 
 |                    for t2 in all_params - {t1} if not isinstance(t2, TypeVar)): | 
 |                 all_params.remove(t1) | 
 |         # It's not a union if there's only one type left. | 
 |         if len(all_params) == 1: | 
 |             return all_params.pop() | 
 |         # Create a new class with these params. | 
 |         self = super().__new__(cls, name, bases, {}, _root=True) | 
 |         self.__union_params__ = tuple(t for t in params if t in all_params) | 
 |         self.__union_set_params__ = frozenset(self.__union_params__) | 
 |         return self | 
 |  | 
 |     def _eval_type(self, globalns, localns): | 
 |         p = tuple(_eval_type(t, globalns, localns) | 
 |                   for t in self.__union_params__) | 
 |         if p == self.__union_params__: | 
 |             return self | 
 |         else: | 
 |             return self.__class__(self.__name__, self.__bases__, {}, | 
 |                                   p, _root=True) | 
 |  | 
 |     def _has_type_var(self): | 
 |         if self.__union_params__: | 
 |             for t in self.__union_params__: | 
 |                 if _has_type_var(t): | 
 |                     return True | 
 |         return False | 
 |  | 
 |     def __repr__(self): | 
 |         r = super().__repr__() | 
 |         if self.__union_params__: | 
 |             r += '[%s]' % (', '.join(_type_repr(t) | 
 |                                      for t in self.__union_params__)) | 
 |         return r | 
 |  | 
 |     def __getitem__(self, parameters): | 
 |         if self.__union_params__ is not None: | 
 |             raise TypeError( | 
 |                 "Cannot subscript an existing Union. Use Union[u, t] instead.") | 
 |         if parameters == (): | 
 |             raise TypeError("Cannot take a Union of no types.") | 
 |         if not isinstance(parameters, tuple): | 
 |             parameters = (parameters,) | 
 |         return self.__class__(self.__name__, self.__bases__, | 
 |                               dict(self.__dict__), parameters, _root=True) | 
 |  | 
 |     def __eq__(self, other): | 
 |         if not isinstance(other, UnionMeta): | 
 |             return NotImplemented | 
 |         return self.__union_set_params__ == other.__union_set_params__ | 
 |  | 
 |     def __hash__(self): | 
 |         return hash(self.__union_set_params__) | 
 |  | 
 |     def __instancecheck__(self, obj): | 
 |         raise TypeError("Unions cannot be used with isinstance().") | 
 |  | 
 |     def __subclasscheck__(self, cls): | 
 |         if cls is Any: | 
 |             return True | 
 |         if self.__union_params__ is None: | 
 |             return isinstance(cls, UnionMeta) | 
 |         elif isinstance(cls, UnionMeta): | 
 |             if cls.__union_params__ is None: | 
 |                 return False | 
 |             return all(issubclass(c, self) for c in (cls.__union_params__)) | 
 |         elif isinstance(cls, TypeVar): | 
 |             if cls in self.__union_params__: | 
 |                 return True | 
 |             if cls.__constraints__: | 
 |                 return issubclass(Union[cls.__constraints__], self) | 
 |             return False | 
 |         else: | 
 |             return any(issubclass(cls, t) for t in self.__union_params__) | 
 |  | 
 |  | 
 | class Union(Final, metaclass=UnionMeta, _root=True): | 
 |     """Union type; Union[X, Y] means either X or Y. | 
 |  | 
 |     To define a union, use e.g. Union[int, str].  Details: | 
 |  | 
 |     - The arguments must be types and there must be at least one. | 
 |  | 
 |     - None as an argument is a special case and is replaced by | 
 |       type(None). | 
 |  | 
 |     - Unions of unions are flattened, e.g.:: | 
 |  | 
 |         Union[Union[int, str], float] == Union[int, str, float] | 
 |  | 
 |     - Unions of a single argument vanish, e.g.:: | 
 |  | 
 |         Union[int] == int  # The constructor actually returns int | 
 |  | 
 |     - Redundant arguments are skipped, e.g.:: | 
 |  | 
 |         Union[int, str, int] == Union[int, str] | 
 |  | 
 |     - When comparing unions, the argument order is ignored, e.g.:: | 
 |  | 
 |         Union[int, str] == Union[str, int] | 
 |  | 
 |     - When two arguments have a subclass relationship, the least | 
 |       derived argument is kept, e.g.:: | 
 |  | 
 |         class Employee: pass | 
 |         class Manager(Employee): pass | 
 |         Union[int, Employee, Manager] == Union[int, Employee] | 
 |         Union[Manager, int, Employee] == Union[int, Employee] | 
 |         Union[Employee, Manager] == Employee | 
 |  | 
 |     - Corollary: if Any is present it is the sole survivor, e.g.:: | 
 |  | 
 |         Union[int, Any] == Any | 
 |  | 
 |     - Similar for object:: | 
 |  | 
 |         Union[int, object] == object | 
 |  | 
 |     - To cut a tie: Union[object, Any] == Union[Any, object] == Any. | 
 |  | 
 |     - You cannot subclass or instantiate a union. | 
 |  | 
 |     - You cannot write Union[X][Y] (what would it mean?). | 
 |  | 
 |     - You can use Optional[X] as a shorthand for Union[X, None]. | 
 |     """ | 
 |  | 
 |     # Unsubscripted Union type has params set to None. | 
 |     __union_params__ = None | 
 |     __union_set_params__ = None | 
 |  | 
 |  | 
 | class OptionalMeta(TypingMeta): | 
 |     """Metaclass for Optional.""" | 
 |  | 
 |     def __new__(cls, name, bases, namespace, _root=False): | 
 |         return super().__new__(cls, name, bases, namespace, _root=_root) | 
 |  | 
 |     def __getitem__(self, arg): | 
 |         arg = _type_check(arg, "Optional[t] requires a single type.") | 
 |         return Union[arg, type(None)] | 
 |  | 
 |  | 
 | class Optional(Final, metaclass=OptionalMeta, _root=True): | 
 |     """Optional type. | 
 |  | 
 |     Optional[X] is equivalent to Union[X, type(None)]. | 
 |     """ | 
 |  | 
 |     __slots__ = () | 
 |  | 
 |  | 
 | class TupleMeta(TypingMeta): | 
 |     """Metaclass for Tuple.""" | 
 |  | 
 |     def __new__(cls, name, bases, namespace, parameters=None, | 
 |                 use_ellipsis=False, _root=False): | 
 |         self = super().__new__(cls, name, bases, namespace, _root=_root) | 
 |         self.__tuple_params__ = parameters | 
 |         self.__tuple_use_ellipsis__ = use_ellipsis | 
 |         return self | 
 |  | 
 |     def _has_type_var(self): | 
 |         if self.__tuple_params__: | 
 |             for t in self.__tuple_params__: | 
 |                 if _has_type_var(t): | 
 |                     return True | 
 |         return False | 
 |  | 
 |     def _eval_type(self, globalns, localns): | 
 |         tp = self.__tuple_params__ | 
 |         if tp is None: | 
 |             return self | 
 |         p = tuple(_eval_type(t, globalns, localns) for t in tp) | 
 |         if p == self.__tuple_params__: | 
 |             return self | 
 |         else: | 
 |             return self.__class__(self.__name__, self.__bases__, {}, | 
 |                                   p, _root=True) | 
 |  | 
 |     def __repr__(self): | 
 |         r = super().__repr__() | 
 |         if self.__tuple_params__ is not None: | 
 |             params = [_type_repr(p) for p in self.__tuple_params__] | 
 |             if self.__tuple_use_ellipsis__: | 
 |                 params.append('...') | 
 |             r += '[%s]' % ( | 
 |                 ', '.join(params)) | 
 |         return r | 
 |  | 
 |     def __getitem__(self, parameters): | 
 |         if self.__tuple_params__ is not None: | 
 |             raise TypeError("Cannot re-parameterize %r" % (self,)) | 
 |         if not isinstance(parameters, tuple): | 
 |             parameters = (parameters,) | 
 |         if len(parameters) == 2 and parameters[1] == Ellipsis: | 
 |             parameters = parameters[:1] | 
 |             use_ellipsis = True | 
 |             msg = "Tuple[t, ...]: t must be a type." | 
 |         else: | 
 |             use_ellipsis = False | 
 |             msg = "Tuple[t0, t1, ...]: each t must be a type." | 
 |         parameters = tuple(_type_check(p, msg) for p in parameters) | 
 |         return self.__class__(self.__name__, self.__bases__, | 
 |                               dict(self.__dict__), parameters, | 
 |                               use_ellipsis=use_ellipsis, _root=True) | 
 |  | 
 |     def __eq__(self, other): | 
 |         if not isinstance(other, TupleMeta): | 
 |             return NotImplemented | 
 |         return self.__tuple_params__ == other.__tuple_params__ | 
 |  | 
 |     def __hash__(self): | 
 |         return hash(self.__tuple_params__) | 
 |  | 
 |     def __instancecheck__(self, obj): | 
 |         raise TypeError("Tuples cannot be used with isinstance().") | 
 |  | 
 |     def __subclasscheck__(self, cls): | 
 |         if cls is Any: | 
 |             return True | 
 |         if not isinstance(cls, type): | 
 |             return super().__subclasscheck__(cls)  # To TypeError. | 
 |         if issubclass(cls, tuple): | 
 |             return True  # Special case. | 
 |         if not isinstance(cls, TupleMeta): | 
 |             return super().__subclasscheck__(cls)  # False. | 
 |         if self.__tuple_params__ is None: | 
 |             return True | 
 |         if cls.__tuple_params__ is None: | 
 |             return False  # ??? | 
 |         if cls.__tuple_use_ellipsis__ != self.__tuple_use_ellipsis__: | 
 |             return False | 
 |         # Covariance. | 
 |         return (len(self.__tuple_params__) == len(cls.__tuple_params__) and | 
 |                 all(issubclass(x, p) | 
 |                     for x, p in zip(cls.__tuple_params__, | 
 |                                     self.__tuple_params__))) | 
 |  | 
 |  | 
 | class Tuple(Final, metaclass=TupleMeta, _root=True): | 
 |     """Tuple type; Tuple[X, Y] is the cross-product type of X and Y. | 
 |  | 
 |     Example: Tuple[T1, T2] is a tuple of two elements corresponding | 
 |     to type variables T1 and T2.  Tuple[int, float, str] is a tuple | 
 |     of an int, a float and a string. | 
 |  | 
 |     To specify a variable-length tuple of homogeneous type, use Sequence[T]. | 
 |     """ | 
 |  | 
 |     __slots__ = () | 
 |  | 
 |  | 
 | class CallableMeta(TypingMeta): | 
 |     """Metaclass for Callable.""" | 
 |  | 
 |     def __new__(cls, name, bases, namespace, _root=False, | 
 |                 args=None, result=None): | 
 |         if args is None and result is None: | 
 |             pass  # Must be 'class Callable'. | 
 |         else: | 
 |             if args is not Ellipsis: | 
 |                 if not isinstance(args, list): | 
 |                     raise TypeError("Callable[args, result]: " | 
 |                                     "args must be a list." | 
 |                                     " Got %.100r." % (args,)) | 
 |                 msg = "Callable[[arg, ...], result]: each arg must be a type." | 
 |                 args = tuple(_type_check(arg, msg) for arg in args) | 
 |             msg = "Callable[args, result]: result must be a type." | 
 |             result = _type_check(result, msg) | 
 |         self = super().__new__(cls, name, bases, namespace, _root=_root) | 
 |         self.__args__ = args | 
 |         self.__result__ = result | 
 |         return self | 
 |  | 
 |     def _has_type_var(self): | 
 |         if self.__args__: | 
 |             for t in self.__args__: | 
 |                 if _has_type_var(t): | 
 |                     return True | 
 |         return _has_type_var(self.__result__) | 
 |  | 
 |     def _eval_type(self, globalns, localns): | 
 |         if self.__args__ is None and self.__result__ is None: | 
 |             return self | 
 |         if self.__args__ is Ellipsis: | 
 |             args = self.__args__ | 
 |         else: | 
 |             args = [_eval_type(t, globalns, localns) for t in self.__args__] | 
 |         result = _eval_type(self.__result__, globalns, localns) | 
 |         if args == self.__args__ and result == self.__result__: | 
 |             return self | 
 |         else: | 
 |             return self.__class__(self.__name__, self.__bases__, {}, | 
 |                                   args=args, result=result, _root=True) | 
 |  | 
 |     def __repr__(self): | 
 |         r = super().__repr__() | 
 |         if self.__args__ is not None or self.__result__ is not None: | 
 |             if self.__args__ is Ellipsis: | 
 |                 args_r = '...' | 
 |             else: | 
 |                 args_r = '[%s]' % ', '.join(_type_repr(t) | 
 |                                             for t in self.__args__) | 
 |             r += '[%s, %s]' % (args_r, _type_repr(self.__result__)) | 
 |         return r | 
 |  | 
 |     def __getitem__(self, parameters): | 
 |         if self.__args__ is not None or self.__result__ is not None: | 
 |             raise TypeError("This Callable type is already parameterized.") | 
 |         if not isinstance(parameters, tuple) or len(parameters) != 2: | 
 |             raise TypeError( | 
 |                 "Callable must be used as Callable[[arg, ...], result].") | 
 |         args, result = parameters | 
 |         return self.__class__(self.__name__, self.__bases__, | 
 |                               dict(self.__dict__), _root=True, | 
 |                               args=args, result=result) | 
 |  | 
 |     def __eq__(self, other): | 
 |         if not isinstance(other, CallableMeta): | 
 |             return NotImplemented | 
 |         return (self.__args__ == other.__args__ and | 
 |                 self.__result__ == other.__result__) | 
 |  | 
 |     def __hash__(self): | 
 |         return hash(self.__args__) ^ hash(self.__result__) | 
 |  | 
 |     def __instancecheck__(self, obj): | 
 |         # For unparametrized Callable we allow this, because | 
 |         # typing.Callable should be equivalent to | 
 |         # collections.abc.Callable. | 
 |         if self.__args__ is None and self.__result__ is None: | 
 |             return isinstance(obj, collections_abc.Callable) | 
 |         else: | 
 |             raise TypeError("Callable[] cannot be used with isinstance().") | 
 |  | 
 |     def __subclasscheck__(self, cls): | 
 |         if cls is Any: | 
 |             return True | 
 |         if not isinstance(cls, CallableMeta): | 
 |             return super().__subclasscheck__(cls) | 
 |         if self.__args__ is None and self.__result__ is None: | 
 |             return True | 
 |         # We're not doing covariance or contravariance -- this is *invariance*. | 
 |         return self == cls | 
 |  | 
 |  | 
 | class Callable(Final, metaclass=CallableMeta, _root=True): | 
 |     """Callable type; Callable[[int], str] is a function of (int) -> str. | 
 |  | 
 |     The subscription syntax must always be used with exactly two | 
 |     values: the argument list and the return type.  The argument list | 
 |     must be a list of types; the return type must be a single type. | 
 |  | 
 |     There is no syntax to indicate optional or keyword arguments, | 
 |     such function types are rarely used as callback types. | 
 |     """ | 
 |  | 
 |     __slots__ = () | 
 |  | 
 |  | 
 | def _gorg(a): | 
 |     """Return the farthest origin of a generic class.""" | 
 |     assert isinstance(a, GenericMeta) | 
 |     while a.__origin__ is not None: | 
 |         a = a.__origin__ | 
 |     return a | 
 |  | 
 |  | 
 | def _geqv(a, b): | 
 |     """Return whether two generic classes are equivalent. | 
 |  | 
 |     The intention is to consider generic class X and any of its | 
 |     parameterized forms (X[T], X[int], etc.)  as equivalent. | 
 |  | 
 |     However, X is not equivalent to a subclass of X. | 
 |  | 
 |     The relation is reflexive, symmetric and transitive. | 
 |     """ | 
 |     assert isinstance(a, GenericMeta) and isinstance(b, GenericMeta) | 
 |     # Reduce each to its origin. | 
 |     return _gorg(a) is _gorg(b) | 
 |  | 
 |  | 
 | class GenericMeta(TypingMeta, abc.ABCMeta): | 
 |     """Metaclass for generic types.""" | 
 |  | 
 |     # TODO: Constrain more how Generic is used; only a few | 
 |     # standard patterns should be allowed. | 
 |  | 
 |     # TODO: Use a more precise rule than matching __name__ to decide | 
 |     # whether two classes are the same.  Also, save the formal | 
 |     # parameters.  (These things are related!  A solution lies in | 
 |     # using origin.) | 
 |  | 
 |     __extra__ = None | 
 |  | 
 |     def __new__(cls, name, bases, namespace, | 
 |                 parameters=None, origin=None, extra=None): | 
 |         if parameters is None: | 
 |             # Extract parameters from direct base classes.  Only | 
 |             # direct bases are considered and only those that are | 
 |             # themselves generic, and parameterized with type | 
 |             # variables.  Don't use bases like Any, Union, Tuple, | 
 |             # Callable or type variables. | 
 |             params = None | 
 |             for base in bases: | 
 |                 if isinstance(base, TypingMeta): | 
 |                     if not isinstance(base, GenericMeta): | 
 |                         raise TypeError( | 
 |                             "You cannot inherit from magic class %s" % | 
 |                             repr(base)) | 
 |                     if base.__parameters__ is None: | 
 |                         continue  # The base is unparameterized. | 
 |                     for bp in base.__parameters__: | 
 |                         if _has_type_var(bp) and not isinstance(bp, TypeVar): | 
 |                             raise TypeError( | 
 |                                 "Cannot inherit from a generic class " | 
 |                                 "parameterized with " | 
 |                                 "non-type-variable %s" % bp) | 
 |                         if params is None: | 
 |                             params = [] | 
 |                         if bp not in params: | 
 |                             params.append(bp) | 
 |             if params is not None: | 
 |                 parameters = tuple(params) | 
 |         self = super().__new__(cls, name, bases, namespace, _root=True) | 
 |         self.__parameters__ = parameters | 
 |         if extra is not None: | 
 |             self.__extra__ = extra | 
 |         # Else __extra__ is inherited, eventually from the | 
 |         # (meta-)class default above. | 
 |         self.__origin__ = origin | 
 |         return self | 
 |  | 
 |     def _has_type_var(self): | 
 |         if self.__parameters__: | 
 |             for t in self.__parameters__: | 
 |                 if _has_type_var(t): | 
 |                     return True | 
 |         return False | 
 |  | 
 |     def __repr__(self): | 
 |         r = super().__repr__() | 
 |         if self.__parameters__ is not None: | 
 |             r += '[%s]' % ( | 
 |                 ', '.join(_type_repr(p) for p in self.__parameters__)) | 
 |         return r | 
 |  | 
 |     def __eq__(self, other): | 
 |         if not isinstance(other, GenericMeta): | 
 |             return NotImplemented | 
 |         return (_geqv(self, other) and | 
 |                 self.__parameters__ == other.__parameters__) | 
 |  | 
 |     def __hash__(self): | 
 |         return hash((self.__name__, self.__parameters__)) | 
 |  | 
 |     def __getitem__(self, params): | 
 |         if not isinstance(params, tuple): | 
 |             params = (params,) | 
 |         if not params: | 
 |             raise TypeError("Cannot have empty parameter list") | 
 |         msg = "Parameters to generic types must be types." | 
 |         params = tuple(_type_check(p, msg) for p in params) | 
 |         if self.__parameters__ is None: | 
 |             for p in params: | 
 |                 if not isinstance(p, TypeVar): | 
 |                     raise TypeError("Initial parameters must be " | 
 |                                     "type variables; got %s" % p) | 
 |             if len(set(params)) != len(params): | 
 |                 raise TypeError( | 
 |                     "All type variables in Generic[...] must be distinct.") | 
 |         else: | 
 |             if len(params) != len(self.__parameters__): | 
 |                 raise TypeError("Cannot change parameter count from %d to %d" % | 
 |                                 (len(self.__parameters__), len(params))) | 
 |             for new, old in zip(params, self.__parameters__): | 
 |                 if isinstance(old, TypeVar): | 
 |                     if not old.__constraints__: | 
 |                         # Substituting for an unconstrained TypeVar is OK. | 
 |                         continue | 
 |                     if issubclass(new, Union[old.__constraints__]): | 
 |                         # Specializing a constrained type variable is OK. | 
 |                         continue | 
 |                 if not issubclass(new, old): | 
 |                     raise TypeError( | 
 |                         "Cannot substitute %s for %s in %s" % | 
 |                         (_type_repr(new), _type_repr(old), self)) | 
 |  | 
 |         return self.__class__(self.__name__, (self,) + self.__bases__, | 
 |                               dict(self.__dict__), | 
 |                               parameters=params, | 
 |                               origin=self, | 
 |                               extra=self.__extra__) | 
 |  | 
 |     def __instancecheck__(self, instance): | 
 |         # Since we extend ABC.__subclasscheck__ and | 
 |         # ABC.__instancecheck__ inlines the cache checking done by the | 
 |         # latter, we must extend __instancecheck__ too. For simplicity | 
 |         # we just skip the cache check -- instance checks for generic | 
 |         # classes are supposed to be rare anyways. | 
 |         return self.__subclasscheck__(instance.__class__) | 
 |  | 
 |     def __subclasscheck__(self, cls): | 
 |         if cls is Any: | 
 |             return True | 
 |         if isinstance(cls, GenericMeta): | 
 |             # For a class C(Generic[T]) where T is co-variant, | 
 |             # C[X] is a subclass of C[Y] iff X is a subclass of Y. | 
 |             origin = self.__origin__ | 
 |             if origin is not None and origin is cls.__origin__: | 
 |                 assert len(self.__parameters__) == len(origin.__parameters__) | 
 |                 assert len(cls.__parameters__) == len(origin.__parameters__) | 
 |                 for p_self, p_cls, p_origin in zip(self.__parameters__, | 
 |                                                    cls.__parameters__, | 
 |                                                    origin.__parameters__): | 
 |                     if isinstance(p_origin, TypeVar): | 
 |                         if p_origin.__covariant__: | 
 |                             # Covariant -- p_cls must be a subclass of p_self. | 
 |                             if not issubclass(p_cls, p_self): | 
 |                                 break | 
 |                         elif p_origin.__contravariant__: | 
 |                             # Contravariant.  I think it's the opposite. :-) | 
 |                             if not issubclass(p_self, p_cls): | 
 |                                 break | 
 |                         else: | 
 |                             # Invariant -- p_cls and p_self must equal. | 
 |                             if p_self != p_cls: | 
 |                                 break | 
 |                     else: | 
 |                         # If the origin's parameter is not a typevar, | 
 |                         # insist on invariance. | 
 |                         if p_self != p_cls: | 
 |                             break | 
 |                 else: | 
 |                     return True | 
 |                 # If we break out of the loop, the superclass gets a chance. | 
 |         if super().__subclasscheck__(cls): | 
 |             return True | 
 |         if self.__extra__ is None or isinstance(cls, GenericMeta): | 
 |             return False | 
 |         return issubclass(cls, self.__extra__) | 
 |  | 
 |  | 
 | class Generic(metaclass=GenericMeta): | 
 |     """Abstract base class for generic types. | 
 |  | 
 |     A generic type is typically declared by inheriting from an | 
 |     instantiation of this class with one or more type variables. | 
 |     For example, a generic mapping type might be defined as:: | 
 |  | 
 |       class Mapping(Generic[KT, VT]): | 
 |           def __getitem__(self, key: KT) -> VT: | 
 |               ... | 
 |           # Etc. | 
 |  | 
 |     This class can then be used as follows:: | 
 |  | 
 |       def lookup_name(mapping: Mapping, key: KT, default: VT) -> VT: | 
 |           try: | 
 |               return mapping[key] | 
 |           except KeyError: | 
 |               return default | 
 |  | 
 |     For clarity the type variables may be redefined, e.g.:: | 
 |  | 
 |       X = TypeVar('X') | 
 |       Y = TypeVar('Y') | 
 |       def lookup_name(mapping: Mapping[X, Y], key: X, default: Y) -> Y: | 
 |           # Same body as above. | 
 |     """ | 
 |  | 
 |     __slots__ = () | 
 |  | 
 |     def __new__(cls, *args, **kwds): | 
 |         next_in_mro = object | 
 |         # Look for the last occurrence of Generic or Generic[...]. | 
 |         for i, c in enumerate(cls.__mro__[:-1]): | 
 |             if isinstance(c, GenericMeta) and _gorg(c) is Generic: | 
 |                 next_in_mro = cls.__mro__[i+1] | 
 |         return next_in_mro.__new__(_gorg(cls)) | 
 |  | 
 |  | 
 | def cast(typ, val): | 
 |     """Cast a value to a type. | 
 |  | 
 |     This returns the value unchanged.  To the type checker this | 
 |     signals that the return value has the designated type, but at | 
 |     runtime we intentionally don't check anything (we want this | 
 |     to be as fast as possible). | 
 |     """ | 
 |     return val | 
 |  | 
 |  | 
 | def _get_defaults(func): | 
 |     """Internal helper to extract the default arguments, by name.""" | 
 |     code = func.__code__ | 
 |     pos_count = code.co_argcount | 
 |     kw_count = code.co_kwonlyargcount | 
 |     arg_names = code.co_varnames | 
 |     kwarg_names = arg_names[pos_count:pos_count + kw_count] | 
 |     arg_names = arg_names[:pos_count] | 
 |     defaults = func.__defaults__ or () | 
 |     kwdefaults = func.__kwdefaults__ | 
 |     res = dict(kwdefaults) if kwdefaults else {} | 
 |     pos_offset = pos_count - len(defaults) | 
 |     for name, value in zip(arg_names[pos_offset:], defaults): | 
 |         assert name not in res | 
 |         res[name] = value | 
 |     return res | 
 |  | 
 |  | 
 | def get_type_hints(obj, globalns=None, localns=None): | 
 |     """Return type hints for a function or method object. | 
 |  | 
 |     This is often the same as obj.__annotations__, but it handles | 
 |     forward references encoded as string literals, and if necessary | 
 |     adds Optional[t] if a default value equal to None is set. | 
 |  | 
 |     BEWARE -- the behavior of globalns and localns is counterintuitive | 
 |     (unless you are familiar with how eval() and exec() work).  The | 
 |     search order is locals first, then globals. | 
 |  | 
 |     - If no dict arguments are passed, an attempt is made to use the | 
 |       globals from obj, and these are also used as the locals.  If the | 
 |       object does not appear to have globals, an exception is raised. | 
 |  | 
 |     - If one dict argument is passed, it is used for both globals and | 
 |       locals. | 
 |  | 
 |     - If two dict arguments are passed, they specify globals and | 
 |       locals, respectively. | 
 |     """ | 
 |     if getattr(obj, '__no_type_check__', None): | 
 |         return {} | 
 |     if globalns is None: | 
 |         globalns = getattr(obj, '__globals__', {}) | 
 |         if localns is None: | 
 |             localns = globalns | 
 |     elif localns is None: | 
 |         localns = globalns | 
 |     defaults = _get_defaults(obj) | 
 |     hints = dict(obj.__annotations__) | 
 |     for name, value in hints.items(): | 
 |         if isinstance(value, str): | 
 |             value = _ForwardRef(value) | 
 |         value = _eval_type(value, globalns, localns) | 
 |         if name in defaults and defaults[name] is None: | 
 |             value = Optional[value] | 
 |         hints[name] = value | 
 |     return hints | 
 |  | 
 |  | 
 | # TODO: Also support this as a class decorator. | 
 | def no_type_check(arg): | 
 |     """Decorator to indicate that annotations are not type hints. | 
 |  | 
 |     The argument must be a class or function; if it is a class, it | 
 |     applies recursively to all methods defined in that class (but not | 
 |     to methods defined in its superclasses or subclasses). | 
 |  | 
 |     This mutates the function(s) in place. | 
 |     """ | 
 |     if isinstance(arg, type): | 
 |         for obj in arg.__dict__.values(): | 
 |             if isinstance(obj, types.FunctionType): | 
 |                 obj.__no_type_check__ = True | 
 |     else: | 
 |         arg.__no_type_check__ = True | 
 |     return arg | 
 |  | 
 |  | 
 | def no_type_check_decorator(decorator): | 
 |     """Decorator to give another decorator the @no_type_check effect. | 
 |  | 
 |     This wraps the decorator with something that wraps the decorated | 
 |     function in @no_type_check. | 
 |     """ | 
 |  | 
 |     @functools.wraps(decorator) | 
 |     def wrapped_decorator(*args, **kwds): | 
 |         func = decorator(*args, **kwds) | 
 |         func = no_type_check(func) | 
 |         return func | 
 |  | 
 |     return wrapped_decorator | 
 |  | 
 |  | 
 | def overload(func): | 
 |     raise RuntimeError("Overloading is only supported in library stubs") | 
 |  | 
 |  | 
 | class _ProtocolMeta(GenericMeta): | 
 |     """Internal metaclass for _Protocol. | 
 |  | 
 |     This exists so _Protocol classes can be generic without deriving | 
 |     from Generic. | 
 |     """ | 
 |  | 
 |     def __instancecheck__(self, obj): | 
 |         raise TypeError("Protocols cannot be used with isinstance().") | 
 |  | 
 |     def __subclasscheck__(self, cls): | 
 |         if not self._is_protocol: | 
 |             # No structural checks since this isn't a protocol. | 
 |             return NotImplemented | 
 |  | 
 |         if self is _Protocol: | 
 |             # Every class is a subclass of the empty protocol. | 
 |             return True | 
 |  | 
 |         # Find all attributes defined in the protocol. | 
 |         attrs = self._get_protocol_attrs() | 
 |  | 
 |         for attr in attrs: | 
 |             if not any(attr in d.__dict__ for d in cls.__mro__): | 
 |                 return False | 
 |         return True | 
 |  | 
 |     def _get_protocol_attrs(self): | 
 |         # Get all Protocol base classes. | 
 |         protocol_bases = [] | 
 |         for c in self.__mro__: | 
 |             if getattr(c, '_is_protocol', False) and c.__name__ != '_Protocol': | 
 |                 protocol_bases.append(c) | 
 |  | 
 |         # Get attributes included in protocol. | 
 |         attrs = set() | 
 |         for base in protocol_bases: | 
 |             for attr in base.__dict__.keys(): | 
 |                 # Include attributes not defined in any non-protocol bases. | 
 |                 for c in self.__mro__: | 
 |                     if (c is not base and attr in c.__dict__ and | 
 |                             not getattr(c, '_is_protocol', False)): | 
 |                         break | 
 |                 else: | 
 |                     if (not attr.startswith('_abc_') and | 
 |                         attr != '__abstractmethods__' and | 
 |                         attr != '_is_protocol' and | 
 |                         attr != '__dict__' and | 
 |                         attr != '__slots__' and | 
 |                         attr != '_get_protocol_attrs' and | 
 |                         attr != '__parameters__' and | 
 |                         attr != '__origin__' and | 
 |                         attr != '__module__'): | 
 |                         attrs.add(attr) | 
 |  | 
 |         return attrs | 
 |  | 
 |  | 
 | class _Protocol(metaclass=_ProtocolMeta): | 
 |     """Internal base class for protocol classes. | 
 |  | 
 |     This implements a simple-minded structural isinstance check | 
 |     (similar but more general than the one-offs in collections.abc | 
 |     such as Hashable). | 
 |     """ | 
 |  | 
 |     __slots__ = () | 
 |  | 
 |     _is_protocol = True | 
 |  | 
 |  | 
 | # Various ABCs mimicking those in collections.abc. | 
 | # A few are simply re-exported for completeness. | 
 |  | 
 | Hashable = collections_abc.Hashable  # Not generic. | 
 |  | 
 |  | 
 | class Awaitable(Generic[T_co], extra=collections_abc.Awaitable): | 
 |     __slots__ = () | 
 |  | 
 |  | 
 | class AsyncIterable(Generic[T_co], extra=collections_abc.AsyncIterable): | 
 |     __slots__ = () | 
 |  | 
 |  | 
 | class AsyncIterator(AsyncIterable[T_co], extra=collections_abc.AsyncIterator): | 
 |     __slots__ = () | 
 |  | 
 |  | 
 | class Iterable(Generic[T_co], extra=collections_abc.Iterable): | 
 |     __slots__ = () | 
 |  | 
 |  | 
 | class Iterator(Iterable[T_co], extra=collections_abc.Iterator): | 
 |     __slots__ = () | 
 |  | 
 |  | 
 | class SupportsInt(_Protocol): | 
 |     __slots__ = () | 
 |  | 
 |     @abstractmethod | 
 |     def __int__(self) -> int: | 
 |         pass | 
 |  | 
 |  | 
 | class SupportsFloat(_Protocol): | 
 |     __slots__ = () | 
 |  | 
 |     @abstractmethod | 
 |     def __float__(self) -> float: | 
 |         pass | 
 |  | 
 |  | 
 | class SupportsComplex(_Protocol): | 
 |     __slots__ = () | 
 |  | 
 |     @abstractmethod | 
 |     def __complex__(self) -> complex: | 
 |         pass | 
 |  | 
 |  | 
 | class SupportsBytes(_Protocol): | 
 |     __slots__ = () | 
 |  | 
 |     @abstractmethod | 
 |     def __bytes__(self) -> bytes: | 
 |         pass | 
 |  | 
 |  | 
 | class SupportsAbs(_Protocol[T_co]): | 
 |     __slots__ = () | 
 |  | 
 |     @abstractmethod | 
 |     def __abs__(self) -> T_co: | 
 |         pass | 
 |  | 
 |  | 
 | class SupportsRound(_Protocol[T_co]): | 
 |     __slots__ = () | 
 |  | 
 |     @abstractmethod | 
 |     def __round__(self, ndigits: int = 0) -> T_co: | 
 |         pass | 
 |  | 
 |  | 
 | class Reversible(_Protocol[T_co]): | 
 |     __slots__ = () | 
 |  | 
 |     @abstractmethod | 
 |     def __reversed__(self) -> 'Iterator[T_co]': | 
 |         pass | 
 |  | 
 |  | 
 | Sized = collections_abc.Sized  # Not generic. | 
 |  | 
 |  | 
 | class Container(Generic[T_co], extra=collections_abc.Container): | 
 |     __slots__ = () | 
 |  | 
 |  | 
 | # Callable was defined earlier. | 
 |  | 
 |  | 
 | class AbstractSet(Sized, Iterable[T_co], Container[T_co], | 
 |                   extra=collections_abc.Set): | 
 |     pass | 
 |  | 
 |  | 
 | class MutableSet(AbstractSet[T], extra=collections_abc.MutableSet): | 
 |     pass | 
 |  | 
 |  | 
 | # NOTE: Only the value type is covariant. | 
 | class Mapping(Sized, Iterable[KT], Container[KT], Generic[VT_co], | 
 |               extra=collections_abc.Mapping): | 
 |     pass | 
 |  | 
 |  | 
 | class MutableMapping(Mapping[KT, VT], extra=collections_abc.MutableMapping): | 
 |     pass | 
 |  | 
 |  | 
 | class Sequence(Sized, Iterable[T_co], Container[T_co], | 
 |                extra=collections_abc.Sequence): | 
 |     pass | 
 |  | 
 |  | 
 | class MutableSequence(Sequence[T], extra=collections_abc.MutableSequence): | 
 |     pass | 
 |  | 
 |  | 
 | class ByteString(Sequence[int], extra=collections_abc.ByteString): | 
 |     pass | 
 |  | 
 |  | 
 | ByteString.register(type(memoryview(b''))) | 
 |  | 
 |  | 
 | class List(list, MutableSequence[T]): | 
 |  | 
 |     def __new__(cls, *args, **kwds): | 
 |         if _geqv(cls, List): | 
 |             raise TypeError("Type List cannot be instantiated; " | 
 |                             "use list() instead") | 
 |         return list.__new__(cls, *args, **kwds) | 
 |  | 
 |  | 
 | class Set(set, MutableSet[T]): | 
 |  | 
 |     def __new__(cls, *args, **kwds): | 
 |         if _geqv(cls, Set): | 
 |             raise TypeError("Type Set cannot be instantiated; " | 
 |                             "use set() instead") | 
 |         return set.__new__(cls, *args, **kwds) | 
 |  | 
 |  | 
 | class _FrozenSetMeta(GenericMeta): | 
 |     """This metaclass ensures set is not a subclass of FrozenSet. | 
 |  | 
 |     Without this metaclass, set would be considered a subclass of | 
 |     FrozenSet, because FrozenSet.__extra__ is collections.abc.Set, and | 
 |     set is a subclass of that. | 
 |     """ | 
 |  | 
 |     def __subclasscheck__(self, cls): | 
 |         if issubclass(cls, Set): | 
 |             return False | 
 |         return super().__subclasscheck__(cls) | 
 |  | 
 |  | 
 | class FrozenSet(frozenset, AbstractSet[T_co], metaclass=_FrozenSetMeta): | 
 |     __slots__ = () | 
 |  | 
 |     def __new__(cls, *args, **kwds): | 
 |         if _geqv(cls, FrozenSet): | 
 |             raise TypeError("Type FrozenSet cannot be instantiated; " | 
 |                             "use frozenset() instead") | 
 |         return frozenset.__new__(cls, *args, **kwds) | 
 |  | 
 |  | 
 | class MappingView(Sized, Iterable[T_co], extra=collections_abc.MappingView): | 
 |     pass | 
 |  | 
 |  | 
 | class KeysView(MappingView[KT], AbstractSet[KT], | 
 |                extra=collections_abc.KeysView): | 
 |     pass | 
 |  | 
 |  | 
 | # TODO: Enable Set[Tuple[KT, VT_co]] instead of Generic[KT, VT_co]. | 
 | class ItemsView(MappingView, Generic[KT, VT_co], | 
 |                 extra=collections_abc.ItemsView): | 
 |     pass | 
 |  | 
 |  | 
 | class ValuesView(MappingView[VT_co], extra=collections_abc.ValuesView): | 
 |     pass | 
 |  | 
 |  | 
 | class Dict(dict, MutableMapping[KT, VT]): | 
 |  | 
 |     def __new__(cls, *args, **kwds): | 
 |         if _geqv(cls, Dict): | 
 |             raise TypeError("Type Dict cannot be instantiated; " | 
 |                             "use dict() instead") | 
 |         return dict.__new__(cls, *args, **kwds) | 
 |  | 
 |  | 
 | # Determine what base class to use for Generator. | 
 | if hasattr(collections_abc, 'Generator'): | 
 |     # Sufficiently recent versions of 3.5 have a Generator ABC. | 
 |     _G_base = collections_abc.Generator | 
 | else: | 
 |     # Fall back on the exact type. | 
 |     _G_base = types.GeneratorType | 
 |  | 
 |  | 
 | class Generator(Iterator[T_co], Generic[T_co, T_contra, V_co], | 
 |                 extra=_G_base): | 
 |     __slots__ = () | 
 |  | 
 |     def __new__(cls, *args, **kwds): | 
 |         if _geqv(cls, Generator): | 
 |             raise TypeError("Type Generator cannot be instantiated; " | 
 |                             "create a subclass instead") | 
 |         return super().__new__(cls, *args, **kwds) | 
 |  | 
 |  | 
 | def NamedTuple(typename, fields): | 
 |     """Typed version of namedtuple. | 
 |  | 
 |     Usage:: | 
 |  | 
 |         Employee = typing.NamedTuple('Employee', [('name', str), 'id', int)]) | 
 |  | 
 |     This is equivalent to:: | 
 |  | 
 |         Employee = collections.namedtuple('Employee', ['name', 'id']) | 
 |  | 
 |     The resulting class has one extra attribute: _field_types, | 
 |     giving a dict mapping field names to types.  (The field names | 
 |     are in the _fields attribute, which is part of the namedtuple | 
 |     API.) | 
 |     """ | 
 |     fields = [(n, t) for n, t in fields] | 
 |     cls = collections.namedtuple(typename, [n for n, t in fields]) | 
 |     cls._field_types = dict(fields) | 
 |     # Set the module to the caller's module (otherwise it'd be 'typing'). | 
 |     try: | 
 |         cls.__module__ = sys._getframe(1).f_globals.get('__name__', '__main__') | 
 |     except (AttributeError, ValueError): | 
 |         pass | 
 |     return cls | 
 |  | 
 |  | 
 | class IO(Generic[AnyStr]): | 
 |     """Generic base class for TextIO and BinaryIO. | 
 |  | 
 |     This is an abstract, generic version of the return of open(). | 
 |  | 
 |     NOTE: This does not distinguish between the different possible | 
 |     classes (text vs. binary, read vs. write vs. read/write, | 
 |     append-only, unbuffered).  The TextIO and BinaryIO subclasses | 
 |     below capture the distinctions between text vs. binary, which is | 
 |     pervasive in the interface; however we currently do not offer a | 
 |     way to track the other distinctions in the type system. | 
 |     """ | 
 |  | 
 |     __slots__ = () | 
 |  | 
 |     @abstractproperty | 
 |     def mode(self) -> str: | 
 |         pass | 
 |  | 
 |     @abstractproperty | 
 |     def name(self) -> str: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def close(self) -> None: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def closed(self) -> bool: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def fileno(self) -> int: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def flush(self) -> None: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def isatty(self) -> bool: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def read(self, n: int = -1) -> AnyStr: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def readable(self) -> bool: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def readline(self, limit: int = -1) -> AnyStr: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def readlines(self, hint: int = -1) -> List[AnyStr]: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def seek(self, offset: int, whence: int = 0) -> int: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def seekable(self) -> bool: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def tell(self) -> int: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def truncate(self, size: int = None) -> int: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def writable(self) -> bool: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def write(self, s: AnyStr) -> int: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def writelines(self, lines: List[AnyStr]) -> None: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def __enter__(self) -> 'IO[AnyStr]': | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def __exit__(self, type, value, traceback) -> None: | 
 |         pass | 
 |  | 
 |  | 
 | class BinaryIO(IO[bytes]): | 
 |     """Typed version of the return of open() in binary mode.""" | 
 |  | 
 |     __slots__ = () | 
 |  | 
 |     @abstractmethod | 
 |     def write(self, s: Union[bytes, bytearray]) -> int: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def __enter__(self) -> 'BinaryIO': | 
 |         pass | 
 |  | 
 |  | 
 | class TextIO(IO[str]): | 
 |     """Typed version of the return of open() in text mode.""" | 
 |  | 
 |     __slots__ = () | 
 |  | 
 |     @abstractproperty | 
 |     def buffer(self) -> BinaryIO: | 
 |         pass | 
 |  | 
 |     @abstractproperty | 
 |     def encoding(self) -> str: | 
 |         pass | 
 |  | 
 |     @abstractproperty | 
 |     def errors(self) -> str: | 
 |         pass | 
 |  | 
 |     @abstractproperty | 
 |     def line_buffering(self) -> bool: | 
 |         pass | 
 |  | 
 |     @abstractproperty | 
 |     def newlines(self) -> Any: | 
 |         pass | 
 |  | 
 |     @abstractmethod | 
 |     def __enter__(self) -> 'TextIO': | 
 |         pass | 
 |  | 
 |  | 
 | class io: | 
 |     """Wrapper namespace for IO generic classes.""" | 
 |  | 
 |     __all__ = ['IO', 'TextIO', 'BinaryIO'] | 
 |     IO = IO | 
 |     TextIO = TextIO | 
 |     BinaryIO = BinaryIO | 
 |  | 
 | io.__name__ = __name__ + '.io' | 
 | sys.modules[io.__name__] = io | 
 |  | 
 |  | 
 | Pattern = _TypeAlias('Pattern', AnyStr, type(stdlib_re.compile('')), | 
 |                      lambda p: p.pattern) | 
 | Match = _TypeAlias('Match', AnyStr, type(stdlib_re.match('', '')), | 
 |                    lambda m: m.re.pattern) | 
 |  | 
 |  | 
 | class re: | 
 |     """Wrapper namespace for re type aliases.""" | 
 |  | 
 |     __all__ = ['Pattern', 'Match'] | 
 |     Pattern = Pattern | 
 |     Match = Match | 
 |  | 
 | re.__name__ = __name__ + '.re' | 
 | sys.modules[re.__name__] = re |