1900 lines
63 KiB
Python
1900 lines
63 KiB
Python
"""
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The typing module: Support for gradual typing as defined by PEP 484.
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At large scale, the structure of the module is following:
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* Imports and exports, all public names should be explicitly added to __all__.
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* Internal helper functions: these should never be used in code outside this module.
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* _SpecialForm and its instances (special forms): Any, NoReturn, ClassVar, Union, Optional
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* Two classes whose instances can be type arguments in addition to types: ForwardRef and TypeVar
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* The core of internal generics API: _GenericAlias and _VariadicGenericAlias, the latter is
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currently only used by Tuple and Callable. All subscripted types like X[int], Union[int, str],
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etc., are instances of either of these classes.
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* The public counterpart of the generics API consists of two classes: Generic and Protocol.
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* Public helper functions: get_type_hints, overload, cast, no_type_check,
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no_type_check_decorator.
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* Generic aliases for collections.abc ABCs and few additional protocols.
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* Special types: NewType, NamedTuple, TypedDict (may be added soon).
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* Wrapper submodules for re and io related types.
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"""
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from abc import abstractmethod, abstractproperty, ABCMeta
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import collections
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import collections.abc
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import contextlib
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import functools
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import operator
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import re as stdlib_re # Avoid confusion with the re we export.
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import sys
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import types
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from types import WrapperDescriptorType, MethodWrapperType, MethodDescriptorType
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# Please keep __all__ alphabetized within each category.
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__all__ = [
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# Super-special typing primitives.
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'Any',
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'Callable',
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'ClassVar',
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'Final',
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'ForwardRef',
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'Generic',
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'Literal',
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'Optional',
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'Protocol',
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'Tuple',
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'Type',
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'TypeVar',
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'Union',
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# ABCs (from collections.abc).
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'AbstractSet', # collections.abc.Set.
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'ByteString',
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'Container',
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'ContextManager',
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'Hashable',
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'ItemsView',
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'Iterable',
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'Iterator',
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'KeysView',
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'Mapping',
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'MappingView',
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'MutableMapping',
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'MutableSequence',
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'MutableSet',
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'Sequence',
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'Sized',
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'ValuesView',
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'Awaitable',
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'AsyncIterator',
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'AsyncIterable',
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'Coroutine',
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'Collection',
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'AsyncGenerator',
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'AsyncContextManager',
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# Structural checks, a.k.a. protocols.
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'Reversible',
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'SupportsAbs',
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'SupportsBytes',
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'SupportsComplex',
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'SupportsFloat',
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'SupportsIndex',
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'SupportsInt',
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'SupportsRound',
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# Concrete collection types.
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'ChainMap',
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'Counter',
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'Deque',
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'Dict',
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'DefaultDict',
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'List',
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'OrderedDict',
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'Set',
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'FrozenSet',
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'NamedTuple', # Not really a type.
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'TypedDict', # Not really a type.
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'Generator',
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# One-off things.
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'AnyStr',
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'cast',
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'final',
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'get_type_hints',
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'NewType',
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'no_type_check',
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'no_type_check_decorator',
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'NoReturn',
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'overload',
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'runtime_checkable',
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'Text',
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'TYPE_CHECKING',
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]
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# The pseudo-submodules 're' and 'io' are part of the public
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# namespace, but excluded from __all__ because they might stomp on
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# legitimate imports of those modules.
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def _type_check(arg, msg, is_argument=True):
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"""Check that the argument is a type, and return it (internal helper).
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As a special case, accept None and return type(None) instead. Also wrap strings
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into ForwardRef instances. Consider several corner cases, for example plain
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special forms like Union are not valid, while Union[int, str] is OK, etc.
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The msg argument is a human-readable error message, e.g::
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"Union[arg, ...]: arg should be a type."
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We append the repr() of the actual value (truncated to 100 chars).
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"""
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invalid_generic_forms = (Generic, Protocol)
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if is_argument:
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invalid_generic_forms = invalid_generic_forms + (ClassVar, Final)
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if arg is None:
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return type(None)
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if isinstance(arg, str):
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return ForwardRef(arg)
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if (isinstance(arg, _GenericAlias) and
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arg.__origin__ in invalid_generic_forms):
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raise TypeError(f"{arg} is not valid as type argument")
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if (isinstance(arg, _SpecialForm) and arg not in (Any, NoReturn) or
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arg in (Generic, Protocol)):
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raise TypeError(f"Plain {arg} is not valid as type argument")
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if isinstance(arg, (type, TypeVar, ForwardRef)):
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return arg
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if not callable(arg):
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raise TypeError(f"{msg} Got {arg!r:.100}.")
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return arg
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def _type_repr(obj):
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"""Return the repr() of an object, special-casing types (internal helper).
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If obj is a type, we return a shorter version than the default
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type.__repr__, based on the module and qualified name, which is
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typically enough to uniquely identify a type. For everything
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else, we fall back on repr(obj).
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"""
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if isinstance(obj, type):
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if obj.__module__ == 'builtins':
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return obj.__qualname__
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return f'{obj.__module__}.{obj.__qualname__}'
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if obj is ...:
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return('...')
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if isinstance(obj, types.FunctionType):
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return obj.__name__
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return repr(obj)
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def _collect_type_vars(types):
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"""Collect all type variable contained in types in order of
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first appearance (lexicographic order). For example::
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_collect_type_vars((T, List[S, T])) == (T, S)
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"""
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tvars = []
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for t in types:
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if isinstance(t, TypeVar) and t not in tvars:
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tvars.append(t)
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if isinstance(t, _GenericAlias) and not t._special:
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tvars.extend([t for t in t.__parameters__ if t not in tvars])
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return tuple(tvars)
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def _subs_tvars(tp, tvars, subs):
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"""Substitute type variables 'tvars' with substitutions 'subs'.
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These two must have the same length.
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"""
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if not isinstance(tp, _GenericAlias):
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return tp
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new_args = list(tp.__args__)
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for a, arg in enumerate(tp.__args__):
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if isinstance(arg, TypeVar):
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for i, tvar in enumerate(tvars):
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if arg == tvar:
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new_args[a] = subs[i]
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else:
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new_args[a] = _subs_tvars(arg, tvars, subs)
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if tp.__origin__ is Union:
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return Union[tuple(new_args)]
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return tp.copy_with(tuple(new_args))
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def _check_generic(cls, parameters):
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"""Check correct count for parameters of a generic cls (internal helper).
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This gives a nice error message in case of count mismatch.
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"""
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if not cls.__parameters__:
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raise TypeError(f"{cls} is not a generic class")
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alen = len(parameters)
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elen = len(cls.__parameters__)
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if alen != elen:
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raise TypeError(f"Too {'many' if alen > elen else 'few'} parameters for {cls};"
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f" actual {alen}, expected {elen}")
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def _remove_dups_flatten(parameters):
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"""An internal helper for Union creation and substitution: flatten Unions
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among parameters, then remove duplicates.
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"""
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# Flatten out Union[Union[...], ...].
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params = []
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for p in parameters:
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if isinstance(p, _GenericAlias) and p.__origin__ is Union:
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params.extend(p.__args__)
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elif isinstance(p, tuple) and len(p) > 0 and p[0] is Union:
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params.extend(p[1:])
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else:
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params.append(p)
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# Weed out strict duplicates, preserving the first of each occurrence.
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all_params = set(params)
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if len(all_params) < len(params):
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new_params = []
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for t in params:
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if t in all_params:
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new_params.append(t)
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all_params.remove(t)
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params = new_params
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assert not all_params, all_params
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return tuple(params)
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_cleanups = []
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def _tp_cache(func):
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"""Internal wrapper caching __getitem__ of generic types with a fallback to
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original function for non-hashable arguments.
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"""
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cached = functools.lru_cache()(func)
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_cleanups.append(cached.cache_clear)
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@functools.wraps(func)
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def inner(*args, **kwds):
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try:
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return cached(*args, **kwds)
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except TypeError:
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pass # All real errors (not unhashable args) are raised below.
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return func(*args, **kwds)
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return inner
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def _eval_type(t, globalns, localns):
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"""Evaluate all forward reverences in the given type t.
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For use of globalns and localns see the docstring for get_type_hints().
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"""
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if isinstance(t, ForwardRef):
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return t._evaluate(globalns, localns)
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if isinstance(t, _GenericAlias):
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ev_args = tuple(_eval_type(a, globalns, localns) for a in t.__args__)
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if ev_args == t.__args__:
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return t
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res = t.copy_with(ev_args)
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res._special = t._special
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return res
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return t
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class _Final:
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"""Mixin to prohibit subclassing"""
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__slots__ = ('__weakref__',)
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def __init_subclass__(self, *args, **kwds):
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if '_root' not in kwds:
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raise TypeError("Cannot subclass special typing classes")
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class _Immutable:
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"""Mixin to indicate that object should not be copied."""
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def __copy__(self):
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return self
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def __deepcopy__(self, memo):
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return self
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class _SpecialForm(_Final, _Immutable, _root=True):
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"""Internal indicator of special typing constructs.
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See _doc instance attribute for specific docs.
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"""
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__slots__ = ('_name', '_doc')
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def __new__(cls, *args, **kwds):
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"""Constructor.
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This only exists to give a better error message in case
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someone tries to subclass a special typing object (not a good idea).
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"""
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if (len(args) == 3 and
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isinstance(args[0], str) and
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isinstance(args[1], tuple)):
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# Close enough.
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raise TypeError(f"Cannot subclass {cls!r}")
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return super().__new__(cls)
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def __init__(self, name, doc):
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self._name = name
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self._doc = doc
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def __eq__(self, other):
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if not isinstance(other, _SpecialForm):
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return NotImplemented
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return self._name == other._name
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def __hash__(self):
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return hash((self._name,))
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def __repr__(self):
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return 'typing.' + self._name
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def __reduce__(self):
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return self._name
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def __call__(self, *args, **kwds):
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raise TypeError(f"Cannot instantiate {self!r}")
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def __instancecheck__(self, obj):
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raise TypeError(f"{self} cannot be used with isinstance()")
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def __subclasscheck__(self, cls):
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raise TypeError(f"{self} cannot be used with issubclass()")
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@_tp_cache
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def __getitem__(self, parameters):
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if self._name in ('ClassVar', 'Final'):
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item = _type_check(parameters, f'{self._name} accepts only single type.')
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return _GenericAlias(self, (item,))
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if self._name == 'Union':
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if parameters == ():
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raise TypeError("Cannot take a Union of no types.")
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if not isinstance(parameters, tuple):
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parameters = (parameters,)
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msg = "Union[arg, ...]: each arg must be a type."
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parameters = tuple(_type_check(p, msg) for p in parameters)
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parameters = _remove_dups_flatten(parameters)
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if len(parameters) == 1:
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return parameters[0]
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return _GenericAlias(self, parameters)
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if self._name == 'Optional':
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arg = _type_check(parameters, "Optional[t] requires a single type.")
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return Union[arg, type(None)]
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if self._name == 'Literal':
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# There is no '_type_check' call because arguments to Literal[...] are
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# values, not types.
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return _GenericAlias(self, parameters)
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raise TypeError(f"{self} is not subscriptable")
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Any = _SpecialForm('Any', doc=
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"""Special type indicating an unconstrained type.
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- Any is compatible with every type.
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- Any assumed to have all methods.
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- All values assumed to be instances of Any.
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Note that all the above statements are true from the point of view of
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static type checkers. At runtime, Any should not be used with instance
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or class checks.
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""")
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NoReturn = _SpecialForm('NoReturn', doc=
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"""Special type indicating functions that never return.
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Example::
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from typing import NoReturn
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def stop() -> NoReturn:
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raise Exception('no way')
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This type is invalid in other positions, e.g., ``List[NoReturn]``
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will fail in static type checkers.
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""")
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ClassVar = _SpecialForm('ClassVar', doc=
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"""Special type construct to mark class variables.
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An annotation wrapped in ClassVar indicates that a given
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attribute is intended to be used as a class variable and
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should not be set on instances of that class. Usage::
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class Starship:
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stats: ClassVar[Dict[str, int]] = {} # class variable
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damage: int = 10 # instance variable
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ClassVar accepts only types and cannot be further subscribed.
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Note that ClassVar is not a class itself, and should not
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be used with isinstance() or issubclass().
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""")
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Final = _SpecialForm('Final', doc=
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"""Special typing construct to indicate final names to type checkers.
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A final name cannot be re-assigned or overridden in a subclass.
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For example:
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MAX_SIZE: Final = 9000
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MAX_SIZE += 1 # Error reported by type checker
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class Connection:
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TIMEOUT: Final[int] = 10
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class FastConnector(Connection):
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TIMEOUT = 1 # Error reported by type checker
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There is no runtime checking of these properties.
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""")
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Union = _SpecialForm('Union', doc=
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"""Union type; Union[X, Y] means either X or Y.
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To define a union, use e.g. Union[int, str]. Details:
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- The arguments must be types and there must be at least one.
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- None as an argument is a special case and is replaced by
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type(None).
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- Unions of unions are flattened, e.g.::
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Union[Union[int, str], float] == Union[int, str, float]
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- Unions of a single argument vanish, e.g.::
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Union[int] == int # The constructor actually returns int
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- Redundant arguments are skipped, e.g.::
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Union[int, str, int] == Union[int, str]
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- When comparing unions, the argument order is ignored, e.g.::
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Union[int, str] == Union[str, int]
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- You cannot subclass or instantiate a union.
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- You can use Optional[X] as a shorthand for Union[X, None].
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""")
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Optional = _SpecialForm('Optional', doc=
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"""Optional type.
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Optional[X] is equivalent to Union[X, None].
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""")
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Literal = _SpecialForm('Literal', doc=
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"""Special typing form to define literal types (a.k.a. value types).
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This form can be used to indicate to type checkers that the corresponding
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variable or function parameter has a value equivalent to the provided
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literal (or one of several literals):
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def validate_simple(data: Any) -> Literal[True]: # always returns True
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...
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MODE = Literal['r', 'rb', 'w', 'wb']
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def open_helper(file: str, mode: MODE) -> str:
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...
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open_helper('/some/path', 'r') # Passes type check
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open_helper('/other/path', 'typo') # Error in type checker
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Literal[...] cannot be subclassed. At runtime, an arbitrary value
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is allowed as type argument to Literal[...], but type checkers may
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impose restrictions.
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""")
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class ForwardRef(_Final, _root=True):
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"""Internal wrapper to hold a forward reference."""
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__slots__ = ('__forward_arg__', '__forward_code__',
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'__forward_evaluated__', '__forward_value__',
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'__forward_is_argument__')
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def __init__(self, arg, is_argument=True):
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if not isinstance(arg, str):
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raise TypeError(f"Forward reference must be a string -- got {arg!r}")
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try:
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code = compile(arg, '<string>', 'eval')
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except SyntaxError:
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raise SyntaxError(f"Forward reference must be an expression -- got {arg!r}")
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self.__forward_arg__ = arg
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self.__forward_code__ = code
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self.__forward_evaluated__ = False
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self.__forward_value__ = None
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self.__forward_is_argument__ = is_argument
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def _evaluate(self, globalns, localns):
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if not self.__forward_evaluated__ or localns is not globalns:
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if globalns is None and localns is None:
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globalns = localns = {}
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elif globalns is None:
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globalns = localns
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elif localns is None:
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localns = globalns
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self.__forward_value__ = _type_check(
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eval(self.__forward_code__, globalns, localns),
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"Forward references must evaluate to types.",
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is_argument=self.__forward_is_argument__)
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self.__forward_evaluated__ = True
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return self.__forward_value__
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def __eq__(self, other):
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if not isinstance(other, ForwardRef):
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return NotImplemented
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return (self.__forward_arg__ == other.__forward_arg__ and
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self.__forward_value__ == other.__forward_value__)
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def __hash__(self):
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return hash((self.__forward_arg__, self.__forward_value__))
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def __repr__(self):
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return f'ForwardRef({self.__forward_arg__!r})'
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class TypeVar(_Final, _Immutable, _root=True):
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"""Type variable.
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Usage::
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T = TypeVar('T') # Can be anything
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A = TypeVar('A', str, bytes) # Must be str or bytes
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Type variables exist primarily for the benefit of static type
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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) -> List[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) and issubclass(C, T) will raise TypeError.
|
|
|
|
Type variables defined with covariant=True or contravariant=True
|
|
can be used to declare covariant or contravariant generic types.
|
|
See PEP 484 for more details. By default generic types are invariant
|
|
in all type variables.
|
|
|
|
Type variables can be introspected. e.g.:
|
|
|
|
T.__name__ == 'T'
|
|
T.__constraints__ == ()
|
|
T.__covariant__ == False
|
|
T.__contravariant__ = False
|
|
A.__constraints__ == (str, bytes)
|
|
|
|
Note that only type variables defined in global scope can be pickled.
|
|
"""
|
|
|
|
__slots__ = ('__name__', '__bound__', '__constraints__',
|
|
'__covariant__', '__contravariant__')
|
|
|
|
def __init__(self, name, *constraints, bound=None,
|
|
covariant=False, contravariant=False):
|
|
self.__name__ = name
|
|
if covariant and contravariant:
|
|
raise ValueError("Bivariant types 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
|
|
def_mod = sys._getframe(1).f_globals['__name__'] # for pickling
|
|
if def_mod != 'typing':
|
|
self.__module__ = def_mod
|
|
|
|
def __repr__(self):
|
|
if self.__covariant__:
|
|
prefix = '+'
|
|
elif self.__contravariant__:
|
|
prefix = '-'
|
|
else:
|
|
prefix = '~'
|
|
return prefix + self.__name__
|
|
|
|
def __reduce__(self):
|
|
return self.__name__
|
|
|
|
|
|
# Special typing constructs Union, Optional, Generic, Callable and Tuple
|
|
# use three special attributes for internal bookkeeping of generic types:
|
|
# * __parameters__ is a tuple of unique free type parameters of a generic
|
|
# type, for example, Dict[T, T].__parameters__ == (T,);
|
|
# * __origin__ keeps a reference to a type that was subscripted,
|
|
# e.g., Union[T, int].__origin__ == Union, or the non-generic version of
|
|
# the type.
|
|
# * __args__ is a tuple of all arguments used in subscripting,
|
|
# e.g., Dict[T, int].__args__ == (T, int).
|
|
|
|
|
|
# Mapping from non-generic type names that have a generic alias in typing
|
|
# but with a different name.
|
|
_normalize_alias = {'list': 'List',
|
|
'tuple': 'Tuple',
|
|
'dict': 'Dict',
|
|
'set': 'Set',
|
|
'frozenset': 'FrozenSet',
|
|
'deque': 'Deque',
|
|
'defaultdict': 'DefaultDict',
|
|
'type': 'Type',
|
|
'Set': 'AbstractSet'}
|
|
|
|
def _is_dunder(attr):
|
|
return attr.startswith('__') and attr.endswith('__')
|
|
|
|
|
|
class _GenericAlias(_Final, _root=True):
|
|
"""The central part of internal API.
|
|
|
|
This represents a generic version of type 'origin' with type arguments 'params'.
|
|
There are two kind of these aliases: user defined and special. The special ones
|
|
are wrappers around builtin collections and ABCs in collections.abc. These must
|
|
have 'name' always set. If 'inst' is False, then the alias can't be instantiated,
|
|
this is used by e.g. typing.List and typing.Dict.
|
|
"""
|
|
def __init__(self, origin, params, *, inst=True, special=False, name=None):
|
|
self._inst = inst
|
|
self._special = special
|
|
if special and name is None:
|
|
orig_name = origin.__name__
|
|
name = _normalize_alias.get(orig_name, orig_name)
|
|
self._name = name
|
|
if not isinstance(params, tuple):
|
|
params = (params,)
|
|
self.__origin__ = origin
|
|
self.__args__ = tuple(... if a is _TypingEllipsis else
|
|
() if a is _TypingEmpty else
|
|
a for a in params)
|
|
self.__parameters__ = _collect_type_vars(params)
|
|
self.__slots__ = None # This is not documented.
|
|
if not name:
|
|
self.__module__ = origin.__module__
|
|
|
|
@_tp_cache
|
|
def __getitem__(self, params):
|
|
if self.__origin__ in (Generic, Protocol):
|
|
# Can't subscript Generic[...] or Protocol[...].
|
|
raise TypeError(f"Cannot subscript already-subscripted {self}")
|
|
if not isinstance(params, tuple):
|
|
params = (params,)
|
|
msg = "Parameters to generic types must be types."
|
|
params = tuple(_type_check(p, msg) for p in params)
|
|
_check_generic(self, params)
|
|
return _subs_tvars(self, self.__parameters__, params)
|
|
|
|
def copy_with(self, params):
|
|
# We don't copy self._special.
|
|
return _GenericAlias(self.__origin__, params, name=self._name, inst=self._inst)
|
|
|
|
def __repr__(self):
|
|
if (self._name != 'Callable' or
|
|
len(self.__args__) == 2 and self.__args__[0] is Ellipsis):
|
|
if self._name:
|
|
name = 'typing.' + self._name
|
|
else:
|
|
name = _type_repr(self.__origin__)
|
|
if not self._special:
|
|
args = f'[{", ".join([_type_repr(a) for a in self.__args__])}]'
|
|
else:
|
|
args = ''
|
|
return (f'{name}{args}')
|
|
if self._special:
|
|
return 'typing.Callable'
|
|
return (f'typing.Callable'
|
|
f'[[{", ".join([_type_repr(a) for a in self.__args__[:-1]])}], '
|
|
f'{_type_repr(self.__args__[-1])}]')
|
|
|
|
def __eq__(self, other):
|
|
if not isinstance(other, _GenericAlias):
|
|
return NotImplemented
|
|
if self.__origin__ != other.__origin__:
|
|
return False
|
|
if self.__origin__ is Union and other.__origin__ is Union:
|
|
return frozenset(self.__args__) == frozenset(other.__args__)
|
|
return self.__args__ == other.__args__
|
|
|
|
def __hash__(self):
|
|
if self.__origin__ is Union:
|
|
return hash((Union, frozenset(self.__args__)))
|
|
return hash((self.__origin__, self.__args__))
|
|
|
|
def __call__(self, *args, **kwargs):
|
|
if not self._inst:
|
|
raise TypeError(f"Type {self._name} cannot be instantiated; "
|
|
f"use {self._name.lower()}() instead")
|
|
result = self.__origin__(*args, **kwargs)
|
|
try:
|
|
result.__orig_class__ = self
|
|
except AttributeError:
|
|
pass
|
|
return result
|
|
|
|
def __mro_entries__(self, bases):
|
|
if self._name: # generic version of an ABC or built-in class
|
|
res = []
|
|
if self.__origin__ not in bases:
|
|
res.append(self.__origin__)
|
|
i = bases.index(self)
|
|
if not any(isinstance(b, _GenericAlias) or issubclass(b, Generic)
|
|
for b in bases[i+1:]):
|
|
res.append(Generic)
|
|
return tuple(res)
|
|
if self.__origin__ is Generic:
|
|
if Protocol in bases:
|
|
return ()
|
|
i = bases.index(self)
|
|
for b in bases[i+1:]:
|
|
if isinstance(b, _GenericAlias) and b is not self:
|
|
return ()
|
|
return (self.__origin__,)
|
|
|
|
def __getattr__(self, attr):
|
|
# We are careful for copy and pickle.
|
|
# Also for simplicity we just don't relay all dunder names
|
|
if '__origin__' in self.__dict__ and not _is_dunder(attr):
|
|
return getattr(self.__origin__, attr)
|
|
raise AttributeError(attr)
|
|
|
|
def __setattr__(self, attr, val):
|
|
if _is_dunder(attr) or attr in ('_name', '_inst', '_special'):
|
|
super().__setattr__(attr, val)
|
|
else:
|
|
setattr(self.__origin__, attr, val)
|
|
|
|
def __instancecheck__(self, obj):
|
|
return self.__subclasscheck__(type(obj))
|
|
|
|
def __subclasscheck__(self, cls):
|
|
if self._special:
|
|
if not isinstance(cls, _GenericAlias):
|
|
return issubclass(cls, self.__origin__)
|
|
if cls._special:
|
|
return issubclass(cls.__origin__, self.__origin__)
|
|
raise TypeError("Subscripted generics cannot be used with"
|
|
" class and instance checks")
|
|
|
|
def __reduce__(self):
|
|
if self._special:
|
|
return self._name
|
|
|
|
if self._name:
|
|
origin = globals()[self._name]
|
|
else:
|
|
origin = self.__origin__
|
|
if (origin is Callable and
|
|
not (len(self.__args__) == 2 and self.__args__[0] is Ellipsis)):
|
|
args = list(self.__args__[:-1]), self.__args__[-1]
|
|
else:
|
|
args = tuple(self.__args__)
|
|
if len(args) == 1 and not isinstance(args[0], tuple):
|
|
args, = args
|
|
return operator.getitem, (origin, args)
|
|
|
|
|
|
class _VariadicGenericAlias(_GenericAlias, _root=True):
|
|
"""Same as _GenericAlias above but for variadic aliases. Currently,
|
|
this is used only by special internal aliases: Tuple and Callable.
|
|
"""
|
|
def __getitem__(self, params):
|
|
if self._name != 'Callable' or not self._special:
|
|
return self.__getitem_inner__(params)
|
|
if not isinstance(params, tuple) or len(params) != 2:
|
|
raise TypeError("Callable must be used as "
|
|
"Callable[[arg, ...], result].")
|
|
args, result = params
|
|
if args is Ellipsis:
|
|
params = (Ellipsis, result)
|
|
else:
|
|
if not isinstance(args, list):
|
|
raise TypeError(f"Callable[args, result]: args must be a list."
|
|
f" Got {args}")
|
|
params = (tuple(args), result)
|
|
return self.__getitem_inner__(params)
|
|
|
|
@_tp_cache
|
|
def __getitem_inner__(self, params):
|
|
if self.__origin__ is tuple and self._special:
|
|
if params == ():
|
|
return self.copy_with((_TypingEmpty,))
|
|
if not isinstance(params, tuple):
|
|
params = (params,)
|
|
if len(params) == 2 and params[1] is ...:
|
|
msg = "Tuple[t, ...]: t must be a type."
|
|
p = _type_check(params[0], msg)
|
|
return self.copy_with((p, _TypingEllipsis))
|
|
msg = "Tuple[t0, t1, ...]: each t must be a type."
|
|
params = tuple(_type_check(p, msg) for p in params)
|
|
return self.copy_with(params)
|
|
if self.__origin__ is collections.abc.Callable and self._special:
|
|
args, result = params
|
|
msg = "Callable[args, result]: result must be a type."
|
|
result = _type_check(result, msg)
|
|
if args is Ellipsis:
|
|
return self.copy_with((_TypingEllipsis, result))
|
|
msg = "Callable[[arg, ...], result]: each arg must be a type."
|
|
args = tuple(_type_check(arg, msg) for arg in args)
|
|
params = args + (result,)
|
|
return self.copy_with(params)
|
|
return super().__getitem__(params)
|
|
|
|
|
|
class Generic:
|
|
"""Abstract base class for generic types.
|
|
|
|
A generic type is typically declared by inheriting from
|
|
this class parameterized 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[KT, VT], key: KT, default: VT) -> VT:
|
|
try:
|
|
return mapping[key]
|
|
except KeyError:
|
|
return default
|
|
"""
|
|
__slots__ = ()
|
|
_is_protocol = False
|
|
|
|
def __new__(cls, *args, **kwds):
|
|
if cls in (Generic, Protocol):
|
|
raise TypeError(f"Type {cls.__name__} cannot be instantiated; "
|
|
"it can be used only as a base class")
|
|
if super().__new__ is object.__new__ and cls.__init__ is not object.__init__:
|
|
obj = super().__new__(cls)
|
|
else:
|
|
obj = super().__new__(cls, *args, **kwds)
|
|
return obj
|
|
|
|
@_tp_cache
|
|
def __class_getitem__(cls, params):
|
|
if not isinstance(params, tuple):
|
|
params = (params,)
|
|
if not params and cls is not Tuple:
|
|
raise TypeError(
|
|
f"Parameter list to {cls.__qualname__}[...] cannot be empty")
|
|
msg = "Parameters to generic types must be types."
|
|
params = tuple(_type_check(p, msg) for p in params)
|
|
if cls in (Generic, Protocol):
|
|
# Generic and Protocol can only be subscripted with unique type variables.
|
|
if not all(isinstance(p, TypeVar) for p in params):
|
|
raise TypeError(
|
|
f"Parameters to {cls.__name__}[...] must all be type variables")
|
|
if len(set(params)) != len(params):
|
|
raise TypeError(
|
|
f"Parameters to {cls.__name__}[...] must all be unique")
|
|
else:
|
|
# Subscripting a regular Generic subclass.
|
|
_check_generic(cls, params)
|
|
return _GenericAlias(cls, params)
|
|
|
|
def __init_subclass__(cls, *args, **kwargs):
|
|
super().__init_subclass__(*args, **kwargs)
|
|
tvars = []
|
|
if '__orig_bases__' in cls.__dict__:
|
|
error = Generic in cls.__orig_bases__
|
|
else:
|
|
error = Generic in cls.__bases__ and cls.__name__ != 'Protocol'
|
|
if error:
|
|
raise TypeError("Cannot inherit from plain Generic")
|
|
if '__orig_bases__' in cls.__dict__:
|
|
tvars = _collect_type_vars(cls.__orig_bases__)
|
|
# Look for Generic[T1, ..., Tn].
|
|
# If found, tvars must be a subset of it.
|
|
# If not found, tvars is it.
|
|
# Also check for and reject plain Generic,
|
|
# and reject multiple Generic[...].
|
|
gvars = None
|
|
for base in cls.__orig_bases__:
|
|
if (isinstance(base, _GenericAlias) and
|
|
base.__origin__ is Generic):
|
|
if gvars is not None:
|
|
raise TypeError(
|
|
"Cannot inherit from Generic[...] multiple types.")
|
|
gvars = base.__parameters__
|
|
if gvars is not None:
|
|
tvarset = set(tvars)
|
|
gvarset = set(gvars)
|
|
if not tvarset <= gvarset:
|
|
s_vars = ', '.join(str(t) for t in tvars if t not in gvarset)
|
|
s_args = ', '.join(str(g) for g in gvars)
|
|
raise TypeError(f"Some type variables ({s_vars}) are"
|
|
f" not listed in Generic[{s_args}]")
|
|
tvars = gvars
|
|
cls.__parameters__ = tuple(tvars)
|
|
|
|
|
|
class _TypingEmpty:
|
|
"""Internal placeholder for () or []. Used by TupleMeta and CallableMeta
|
|
to allow empty list/tuple in specific places, without allowing them
|
|
to sneak in where prohibited.
|
|
"""
|
|
|
|
|
|
class _TypingEllipsis:
|
|
"""Internal placeholder for ... (ellipsis)."""
|
|
|
|
|
|
_TYPING_INTERNALS = ['__parameters__', '__orig_bases__', '__orig_class__',
|
|
'_is_protocol', '_is_runtime_protocol']
|
|
|
|
_SPECIAL_NAMES = ['__abstractmethods__', '__annotations__', '__dict__', '__doc__',
|
|
'__init__', '__module__', '__new__', '__slots__',
|
|
'__subclasshook__', '__weakref__']
|
|
|
|
# These special attributes will be not collected as protocol members.
|
|
EXCLUDED_ATTRIBUTES = _TYPING_INTERNALS + _SPECIAL_NAMES + ['_MutableMapping__marker']
|
|
|
|
|
|
def _get_protocol_attrs(cls):
|
|
"""Collect protocol members from a protocol class objects.
|
|
|
|
This includes names actually defined in the class dictionary, as well
|
|
as names that appear in annotations. Special names (above) are skipped.
|
|
"""
|
|
attrs = set()
|
|
for base in cls.__mro__[:-1]: # without object
|
|
if base.__name__ in ('Protocol', 'Generic'):
|
|
continue
|
|
annotations = getattr(base, '__annotations__', {})
|
|
for attr in list(base.__dict__.keys()) + list(annotations.keys()):
|
|
if not attr.startswith('_abc_') and attr not in EXCLUDED_ATTRIBUTES:
|
|
attrs.add(attr)
|
|
return attrs
|
|
|
|
|
|
def _is_callable_members_only(cls):
|
|
# PEP 544 prohibits using issubclass() with protocols that have non-method members.
|
|
return all(callable(getattr(cls, attr, None)) for attr in _get_protocol_attrs(cls))
|
|
|
|
|
|
def _no_init(self, *args, **kwargs):
|
|
if type(self)._is_protocol:
|
|
raise TypeError('Protocols cannot be instantiated')
|
|
|
|
|
|
def _allow_reckless_class_cheks():
|
|
"""Allow instnance and class checks for special stdlib modules.
|
|
|
|
The abc and functools modules indiscriminately call isinstance() and
|
|
issubclass() on the whole MRO of a user class, which may contain protocols.
|
|
"""
|
|
try:
|
|
return sys._getframe(3).f_globals['__name__'] in ['abc', 'functools']
|
|
except (AttributeError, ValueError): # For platforms without _getframe().
|
|
return True
|
|
|
|
|
|
_PROTO_WHITELIST = ['Callable', 'Awaitable',
|
|
'Iterable', 'Iterator', 'AsyncIterable', 'AsyncIterator',
|
|
'Hashable', 'Sized', 'Container', 'Collection', 'Reversible',
|
|
'ContextManager', 'AsyncContextManager']
|
|
|
|
|
|
class _ProtocolMeta(ABCMeta):
|
|
# This metaclass is really unfortunate and exists only because of
|
|
# the lack of __instancehook__.
|
|
def __instancecheck__(cls, instance):
|
|
# We need this method for situations where attributes are
|
|
# assigned in __init__.
|
|
if ((not getattr(cls, '_is_protocol', False) or
|
|
_is_callable_members_only(cls)) and
|
|
issubclass(instance.__class__, cls)):
|
|
return True
|
|
if cls._is_protocol:
|
|
if all(hasattr(instance, attr) and
|
|
# All *methods* can be blocked by setting them to None.
|
|
(not callable(getattr(cls, attr, None)) or
|
|
getattr(instance, attr) is not None)
|
|
for attr in _get_protocol_attrs(cls)):
|
|
return True
|
|
return super().__instancecheck__(instance)
|
|
|
|
|
|
class Protocol(Generic, metaclass=_ProtocolMeta):
|
|
"""Base class for protocol classes.
|
|
|
|
Protocol classes are defined as::
|
|
|
|
class Proto(Protocol):
|
|
def meth(self) -> int:
|
|
...
|
|
|
|
Such classes are primarily used with static type checkers that recognize
|
|
structural subtyping (static duck-typing), for example::
|
|
|
|
class C:
|
|
def meth(self) -> int:
|
|
return 0
|
|
|
|
def func(x: Proto) -> int:
|
|
return x.meth()
|
|
|
|
func(C()) # Passes static type check
|
|
|
|
See PEP 544 for details. Protocol classes decorated with
|
|
@typing.runtime_checkable act as simple-minded runtime protocols that check
|
|
only the presence of given attributes, ignoring their type signatures.
|
|
Protocol classes can be generic, they are defined as::
|
|
|
|
class GenProto(Protocol[T]):
|
|
def meth(self) -> T:
|
|
...
|
|
"""
|
|
__slots__ = ()
|
|
_is_protocol = True
|
|
_is_runtime_protocol = False
|
|
|
|
def __init_subclass__(cls, *args, **kwargs):
|
|
super().__init_subclass__(*args, **kwargs)
|
|
|
|
# Determine if this is a protocol or a concrete subclass.
|
|
if not cls.__dict__.get('_is_protocol', False):
|
|
cls._is_protocol = any(b is Protocol for b in cls.__bases__)
|
|
|
|
# Set (or override) the protocol subclass hook.
|
|
def _proto_hook(other):
|
|
if not cls.__dict__.get('_is_protocol', False):
|
|
return NotImplemented
|
|
|
|
# First, perform various sanity checks.
|
|
if not getattr(cls, '_is_runtime_protocol', False):
|
|
if _allow_reckless_class_cheks():
|
|
return NotImplemented
|
|
raise TypeError("Instance and class checks can only be used with"
|
|
" @runtime_checkable protocols")
|
|
if not _is_callable_members_only(cls):
|
|
if _allow_reckless_class_cheks():
|
|
return NotImplemented
|
|
raise TypeError("Protocols with non-method members"
|
|
" don't support issubclass()")
|
|
if not isinstance(other, type):
|
|
# Same error message as for issubclass(1, int).
|
|
raise TypeError('issubclass() arg 1 must be a class')
|
|
|
|
# Second, perform the actual structural compatibility check.
|
|
for attr in _get_protocol_attrs(cls):
|
|
for base in other.__mro__:
|
|
# Check if the members appears in the class dictionary...
|
|
if attr in base.__dict__:
|
|
if base.__dict__[attr] is None:
|
|
return NotImplemented
|
|
break
|
|
|
|
# ...or in annotations, if it is a sub-protocol.
|
|
annotations = getattr(base, '__annotations__', {})
|
|
if (isinstance(annotations, collections.abc.Mapping) and
|
|
attr in annotations and
|
|
issubclass(other, Generic) and other._is_protocol):
|
|
break
|
|
else:
|
|
return NotImplemented
|
|
return True
|
|
|
|
if '__subclasshook__' not in cls.__dict__:
|
|
cls.__subclasshook__ = _proto_hook
|
|
|
|
# We have nothing more to do for non-protocols...
|
|
if not cls._is_protocol:
|
|
return
|
|
|
|
# ... otherwise check consistency of bases, and prohibit instantiation.
|
|
for base in cls.__bases__:
|
|
if not (base in (object, Generic) or
|
|
base.__module__ == 'collections.abc' and base.__name__ in _PROTO_WHITELIST or
|
|
issubclass(base, Generic) and base._is_protocol):
|
|
raise TypeError('Protocols can only inherit from other'
|
|
' protocols, got %r' % base)
|
|
cls.__init__ = _no_init
|
|
|
|
|
|
def runtime_checkable(cls):
|
|
"""Mark a protocol class as a runtime protocol.
|
|
|
|
Such protocol can be used with isinstance() and issubclass().
|
|
Raise TypeError if applied to a non-protocol class.
|
|
This allows a simple-minded structural check very similar to
|
|
one trick ponies in collections.abc such as Iterable.
|
|
For example::
|
|
|
|
@runtime_checkable
|
|
class Closable(Protocol):
|
|
def close(self): ...
|
|
|
|
assert isinstance(open('/some/file'), Closable)
|
|
|
|
Warning: this will check only the presence of the required methods,
|
|
not their type signatures!
|
|
"""
|
|
if not issubclass(cls, Generic) or not cls._is_protocol:
|
|
raise TypeError('@runtime_checkable can be only applied to protocol classes,'
|
|
' got %r' % cls)
|
|
cls._is_runtime_protocol = True
|
|
return 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."""
|
|
try:
|
|
code = func.__code__
|
|
except AttributeError:
|
|
# Some built-in functions don't have __code__, __defaults__, etc.
|
|
return {}
|
|
pos_count = code.co_argcount
|
|
arg_names = code.co_varnames
|
|
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
|
|
|
|
|
|
_allowed_types = (types.FunctionType, types.BuiltinFunctionType,
|
|
types.MethodType, types.ModuleType,
|
|
WrapperDescriptorType, MethodWrapperType, MethodDescriptorType)
|
|
|
|
|
|
def get_type_hints(obj, globalns=None, localns=None):
|
|
"""Return type hints for an 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.
|
|
|
|
The argument may be a module, class, method, or function. The annotations
|
|
are returned as a dictionary. For classes, annotations include also
|
|
inherited members.
|
|
|
|
TypeError is raised if the argument is not of a type that can contain
|
|
annotations, and an empty dictionary is returned if no annotations are
|
|
present.
|
|
|
|
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 (or the respective module's globals for classes),
|
|
and these are also used as the locals. If the object does not appear
|
|
to have globals, an empty dictionary is used.
|
|
|
|
- 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 {}
|
|
# Classes require a special treatment.
|
|
if isinstance(obj, type):
|
|
hints = {}
|
|
for base in reversed(obj.__mro__):
|
|
if globalns is None:
|
|
base_globals = sys.modules[base.__module__].__dict__
|
|
else:
|
|
base_globals = globalns
|
|
ann = base.__dict__.get('__annotations__', {})
|
|
for name, value in ann.items():
|
|
if value is None:
|
|
value = type(None)
|
|
if isinstance(value, str):
|
|
value = ForwardRef(value, is_argument=False)
|
|
value = _eval_type(value, base_globals, localns)
|
|
hints[name] = value
|
|
return hints
|
|
|
|
if globalns is None:
|
|
if isinstance(obj, types.ModuleType):
|
|
globalns = obj.__dict__
|
|
else:
|
|
globalns = getattr(obj, '__globals__', {})
|
|
if localns is None:
|
|
localns = globalns
|
|
elif localns is None:
|
|
localns = globalns
|
|
hints = getattr(obj, '__annotations__', None)
|
|
if hints is None:
|
|
# Return empty annotations for something that _could_ have them.
|
|
if isinstance(obj, _allowed_types):
|
|
return {}
|
|
else:
|
|
raise TypeError('{!r} is not a module, class, method, '
|
|
'or function.'.format(obj))
|
|
defaults = _get_defaults(obj)
|
|
hints = dict(hints)
|
|
for name, value in hints.items():
|
|
if value is None:
|
|
value = type(None)
|
|
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
|
|
|
|
|
|
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 and classes defined in that class
|
|
(but not to methods defined in its superclasses or subclasses).
|
|
|
|
This mutates the function(s) or class(es) in place.
|
|
"""
|
|
if isinstance(arg, type):
|
|
arg_attrs = arg.__dict__.copy()
|
|
for attr, val in arg.__dict__.items():
|
|
if val in arg.__bases__ + (arg,):
|
|
arg_attrs.pop(attr)
|
|
for obj in arg_attrs.values():
|
|
if isinstance(obj, types.FunctionType):
|
|
obj.__no_type_check__ = True
|
|
if isinstance(obj, type):
|
|
no_type_check(obj)
|
|
try:
|
|
arg.__no_type_check__ = True
|
|
except TypeError: # built-in classes
|
|
pass
|
|
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_dummy(*args, **kwds):
|
|
"""Helper for @overload to raise when called."""
|
|
raise NotImplementedError(
|
|
"You should not call an overloaded function. "
|
|
"A series of @overload-decorated functions "
|
|
"outside a stub module should always be followed "
|
|
"by an implementation that is not @overload-ed.")
|
|
|
|
|
|
def overload(func):
|
|
"""Decorator for overloaded functions/methods.
|
|
|
|
In a stub file, place two or more stub definitions for the same
|
|
function in a row, each decorated with @overload. For example:
|
|
|
|
@overload
|
|
def utf8(value: None) -> None: ...
|
|
@overload
|
|
def utf8(value: bytes) -> bytes: ...
|
|
@overload
|
|
def utf8(value: str) -> bytes: ...
|
|
|
|
In a non-stub file (i.e. a regular .py file), do the same but
|
|
follow it with an implementation. The implementation should *not*
|
|
be decorated with @overload. For example:
|
|
|
|
@overload
|
|
def utf8(value: None) -> None: ...
|
|
@overload
|
|
def utf8(value: bytes) -> bytes: ...
|
|
@overload
|
|
def utf8(value: str) -> bytes: ...
|
|
def utf8(value):
|
|
# implementation goes here
|
|
"""
|
|
return _overload_dummy
|
|
|
|
|
|
def final(f):
|
|
"""A decorator to indicate final methods and final classes.
|
|
|
|
Use this decorator to indicate to type checkers that the decorated
|
|
method cannot be overridden, and decorated class cannot be subclassed.
|
|
For example:
|
|
|
|
class Base:
|
|
@final
|
|
def done(self) -> None:
|
|
...
|
|
class Sub(Base):
|
|
def done(self) -> None: # Error reported by type checker
|
|
...
|
|
|
|
@final
|
|
class Leaf:
|
|
...
|
|
class Other(Leaf): # Error reported by type checker
|
|
...
|
|
|
|
There is no runtime checking of these properties.
|
|
"""
|
|
return f
|
|
|
|
|
|
# Some unconstrained type variables. These are used by the container types.
|
|
# (These are not for export.)
|
|
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.
|
|
# Internal type variable used for Type[].
|
|
CT_co = TypeVar('CT_co', covariant=True, bound=type)
|
|
|
|
# A useful type variable with constraints. This represents string types.
|
|
# (This one *is* for export!)
|
|
AnyStr = TypeVar('AnyStr', bytes, str)
|
|
|
|
|
|
# Various ABCs mimicking those in collections.abc.
|
|
def _alias(origin, params, inst=True):
|
|
return _GenericAlias(origin, params, special=True, inst=inst)
|
|
|
|
Hashable = _alias(collections.abc.Hashable, ()) # Not generic.
|
|
Awaitable = _alias(collections.abc.Awaitable, T_co)
|
|
Coroutine = _alias(collections.abc.Coroutine, (T_co, T_contra, V_co))
|
|
AsyncIterable = _alias(collections.abc.AsyncIterable, T_co)
|
|
AsyncIterator = _alias(collections.abc.AsyncIterator, T_co)
|
|
Iterable = _alias(collections.abc.Iterable, T_co)
|
|
Iterator = _alias(collections.abc.Iterator, T_co)
|
|
Reversible = _alias(collections.abc.Reversible, T_co)
|
|
Sized = _alias(collections.abc.Sized, ()) # Not generic.
|
|
Container = _alias(collections.abc.Container, T_co)
|
|
Collection = _alias(collections.abc.Collection, T_co)
|
|
Callable = _VariadicGenericAlias(collections.abc.Callable, (), special=True)
|
|
Callable.__doc__ = \
|
|
"""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 or ellipsis; 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.
|
|
"""
|
|
AbstractSet = _alias(collections.abc.Set, T_co)
|
|
MutableSet = _alias(collections.abc.MutableSet, T)
|
|
# NOTE: Mapping is only covariant in the value type.
|
|
Mapping = _alias(collections.abc.Mapping, (KT, VT_co))
|
|
MutableMapping = _alias(collections.abc.MutableMapping, (KT, VT))
|
|
Sequence = _alias(collections.abc.Sequence, T_co)
|
|
MutableSequence = _alias(collections.abc.MutableSequence, T)
|
|
ByteString = _alias(collections.abc.ByteString, ()) # Not generic
|
|
Tuple = _VariadicGenericAlias(tuple, (), inst=False, special=True)
|
|
Tuple.__doc__ = \
|
|
"""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 Tuple[T, ...].
|
|
"""
|
|
List = _alias(list, T, inst=False)
|
|
Deque = _alias(collections.deque, T)
|
|
Set = _alias(set, T, inst=False)
|
|
FrozenSet = _alias(frozenset, T_co, inst=False)
|
|
MappingView = _alias(collections.abc.MappingView, T_co)
|
|
KeysView = _alias(collections.abc.KeysView, KT)
|
|
ItemsView = _alias(collections.abc.ItemsView, (KT, VT_co))
|
|
ValuesView = _alias(collections.abc.ValuesView, VT_co)
|
|
ContextManager = _alias(contextlib.AbstractContextManager, T_co)
|
|
AsyncContextManager = _alias(contextlib.AbstractAsyncContextManager, T_co)
|
|
Dict = _alias(dict, (KT, VT), inst=False)
|
|
DefaultDict = _alias(collections.defaultdict, (KT, VT))
|
|
OrderedDict = _alias(collections.OrderedDict, (KT, VT))
|
|
Counter = _alias(collections.Counter, T)
|
|
ChainMap = _alias(collections.ChainMap, (KT, VT))
|
|
Generator = _alias(collections.abc.Generator, (T_co, T_contra, V_co))
|
|
AsyncGenerator = _alias(collections.abc.AsyncGenerator, (T_co, T_contra))
|
|
Type = _alias(type, CT_co, inst=False)
|
|
Type.__doc__ = \
|
|
"""A special construct usable to annotate class objects.
|
|
|
|
For example, suppose we have the following classes::
|
|
|
|
class User: ... # Abstract base for User classes
|
|
class BasicUser(User): ...
|
|
class ProUser(User): ...
|
|
class TeamUser(User): ...
|
|
|
|
And a function that takes a class argument that's a subclass of
|
|
User and returns an instance of the corresponding class::
|
|
|
|
U = TypeVar('U', bound=User)
|
|
def new_user(user_class: Type[U]) -> U:
|
|
user = user_class()
|
|
# (Here we could write the user object to a database)
|
|
return user
|
|
|
|
joe = new_user(BasicUser)
|
|
|
|
At this point the type checker knows that joe has type BasicUser.
|
|
"""
|
|
|
|
|
|
@runtime_checkable
|
|
class SupportsInt(Protocol):
|
|
__slots__ = ()
|
|
|
|
@abstractmethod
|
|
def __int__(self) -> int:
|
|
pass
|
|
|
|
|
|
@runtime_checkable
|
|
class SupportsFloat(Protocol):
|
|
__slots__ = ()
|
|
|
|
@abstractmethod
|
|
def __float__(self) -> float:
|
|
pass
|
|
|
|
|
|
@runtime_checkable
|
|
class SupportsComplex(Protocol):
|
|
__slots__ = ()
|
|
|
|
@abstractmethod
|
|
def __complex__(self) -> complex:
|
|
pass
|
|
|
|
|
|
@runtime_checkable
|
|
class SupportsBytes(Protocol):
|
|
__slots__ = ()
|
|
|
|
@abstractmethod
|
|
def __bytes__(self) -> bytes:
|
|
pass
|
|
|
|
|
|
@runtime_checkable
|
|
class SupportsIndex(Protocol):
|
|
__slots__ = ()
|
|
|
|
@abstractmethod
|
|
def __index__(self) -> int:
|
|
pass
|
|
|
|
|
|
@runtime_checkable
|
|
class SupportsAbs(Protocol[T_co]):
|
|
__slots__ = ()
|
|
|
|
@abstractmethod
|
|
def __abs__(self) -> T_co:
|
|
pass
|
|
|
|
|
|
@runtime_checkable
|
|
class SupportsRound(Protocol[T_co]):
|
|
__slots__ = ()
|
|
|
|
@abstractmethod
|
|
def __round__(self, ndigits: int = 0) -> T_co:
|
|
pass
|
|
|
|
|
|
def _make_nmtuple(name, types):
|
|
msg = "NamedTuple('Name', [(f0, t0), (f1, t1), ...]); each t must be a type"
|
|
types = [(n, _type_check(t, msg)) for n, t in types]
|
|
nm_tpl = collections.namedtuple(name, [n for n, t in types])
|
|
# Prior to PEP 526, only _field_types attribute was assigned.
|
|
# Now __annotations__ are used and _field_types is deprecated (remove in 3.9)
|
|
nm_tpl.__annotations__ = nm_tpl._field_types = dict(types)
|
|
try:
|
|
nm_tpl.__module__ = sys._getframe(2).f_globals.get('__name__', '__main__')
|
|
except (AttributeError, ValueError):
|
|
pass
|
|
return nm_tpl
|
|
|
|
|
|
# attributes prohibited to set in NamedTuple class syntax
|
|
_prohibited = ('__new__', '__init__', '__slots__', '__getnewargs__',
|
|
'_fields', '_field_defaults', '_field_types',
|
|
'_make', '_replace', '_asdict', '_source')
|
|
|
|
_special = ('__module__', '__name__', '__qualname__', '__annotations__')
|
|
|
|
|
|
class NamedTupleMeta(type):
|
|
|
|
def __new__(cls, typename, bases, ns):
|
|
if ns.get('_root', False):
|
|
return super().__new__(cls, typename, bases, ns)
|
|
types = ns.get('__annotations__', {})
|
|
nm_tpl = _make_nmtuple(typename, types.items())
|
|
defaults = []
|
|
defaults_dict = {}
|
|
for field_name in types:
|
|
if field_name in ns:
|
|
default_value = ns[field_name]
|
|
defaults.append(default_value)
|
|
defaults_dict[field_name] = default_value
|
|
elif defaults:
|
|
raise TypeError("Non-default namedtuple field {field_name} cannot "
|
|
"follow default field(s) {default_names}"
|
|
.format(field_name=field_name,
|
|
default_names=', '.join(defaults_dict.keys())))
|
|
nm_tpl.__new__.__annotations__ = dict(types)
|
|
nm_tpl.__new__.__defaults__ = tuple(defaults)
|
|
nm_tpl._field_defaults = defaults_dict
|
|
# update from user namespace without overriding special namedtuple attributes
|
|
for key in ns:
|
|
if key in _prohibited:
|
|
raise AttributeError("Cannot overwrite NamedTuple attribute " + key)
|
|
elif key not in _special and key not in nm_tpl._fields:
|
|
setattr(nm_tpl, key, ns[key])
|
|
return nm_tpl
|
|
|
|
|
|
class NamedTuple(metaclass=NamedTupleMeta):
|
|
"""Typed version of namedtuple.
|
|
|
|
Usage in Python versions >= 3.6::
|
|
|
|
class Employee(NamedTuple):
|
|
name: str
|
|
id: int
|
|
|
|
This is equivalent to::
|
|
|
|
Employee = collections.namedtuple('Employee', ['name', 'id'])
|
|
|
|
The resulting class has an extra __annotations__ attribute, giving a
|
|
dict that maps field names to types. (The field names are also in
|
|
the _fields attribute, which is part of the namedtuple API.)
|
|
Alternative equivalent keyword syntax is also accepted::
|
|
|
|
Employee = NamedTuple('Employee', name=str, id=int)
|
|
|
|
In Python versions <= 3.5 use::
|
|
|
|
Employee = NamedTuple('Employee', [('name', str), ('id', int)])
|
|
"""
|
|
_root = True
|
|
|
|
def __new__(self, typename, fields=None, **kwargs):
|
|
if fields is None:
|
|
fields = kwargs.items()
|
|
elif kwargs:
|
|
raise TypeError("Either list of fields or keywords"
|
|
" can be provided to NamedTuple, not both")
|
|
return _make_nmtuple(typename, fields)
|
|
|
|
|
|
def _dict_new(cls, *args, **kwargs):
|
|
return dict(*args, **kwargs)
|
|
|
|
|
|
def _typeddict_new(cls, _typename, _fields=None, **kwargs):
|
|
total = kwargs.pop('total', True)
|
|
if _fields is None:
|
|
_fields = kwargs
|
|
elif kwargs:
|
|
raise TypeError("TypedDict takes either a dict or keyword arguments,"
|
|
" but not both")
|
|
|
|
ns = {'__annotations__': dict(_fields), '__total__': total}
|
|
try:
|
|
# Setting correct module is necessary to make typed dict classes pickleable.
|
|
ns['__module__'] = sys._getframe(1).f_globals.get('__name__', '__main__')
|
|
except (AttributeError, ValueError):
|
|
pass
|
|
|
|
return _TypedDictMeta(_typename, (), ns)
|
|
|
|
|
|
def _check_fails(cls, other):
|
|
# Typed dicts are only for static structural subtyping.
|
|
raise TypeError('TypedDict does not support instance and class checks')
|
|
|
|
|
|
class _TypedDictMeta(type):
|
|
def __new__(cls, name, bases, ns, total=True):
|
|
"""Create new typed dict class object.
|
|
|
|
This method is called directly when TypedDict is subclassed,
|
|
or via _typeddict_new when TypedDict is instantiated. This way
|
|
TypedDict supports all three syntax forms described in its docstring.
|
|
Subclasses and instances of TypedDict return actual dictionaries
|
|
via _dict_new.
|
|
"""
|
|
ns['__new__'] = _typeddict_new if name == 'TypedDict' else _dict_new
|
|
tp_dict = super(_TypedDictMeta, cls).__new__(cls, name, (dict,), ns)
|
|
|
|
anns = ns.get('__annotations__', {})
|
|
msg = "TypedDict('Name', {f0: t0, f1: t1, ...}); each t must be a type"
|
|
anns = {n: _type_check(tp, msg) for n, tp in anns.items()}
|
|
for base in bases:
|
|
anns.update(base.__dict__.get('__annotations__', {}))
|
|
tp_dict.__annotations__ = anns
|
|
if not hasattr(tp_dict, '__total__'):
|
|
tp_dict.__total__ = total
|
|
return tp_dict
|
|
|
|
__instancecheck__ = __subclasscheck__ = _check_fails
|
|
|
|
|
|
class TypedDict(dict, metaclass=_TypedDictMeta):
|
|
"""A simple typed namespace. At runtime it is equivalent to a plain dict.
|
|
|
|
TypedDict creates a dictionary type that expects all of its
|
|
instances to have a certain set of keys, where each key is
|
|
associated with a value of a consistent type. This expectation
|
|
is not checked at runtime but is only enforced by type checkers.
|
|
Usage::
|
|
|
|
class Point2D(TypedDict):
|
|
x: int
|
|
y: int
|
|
label: str
|
|
|
|
a: Point2D = {'x': 1, 'y': 2, 'label': 'good'} # OK
|
|
b: Point2D = {'z': 3, 'label': 'bad'} # Fails type check
|
|
|
|
assert Point2D(x=1, y=2, label='first') == dict(x=1, y=2, label='first')
|
|
|
|
The type info can be accessed via Point2D.__annotations__. TypedDict
|
|
supports two additional equivalent forms::
|
|
|
|
Point2D = TypedDict('Point2D', x=int, y=int, label=str)
|
|
Point2D = TypedDict('Point2D', {'x': int, 'y': int, 'label': str})
|
|
|
|
The class syntax is only supported in Python 3.6+, while two other
|
|
syntax forms work for Python 2.7 and 3.2+
|
|
"""
|
|
|
|
|
|
def NewType(name, tp):
|
|
"""NewType creates simple unique types with almost zero
|
|
runtime overhead. NewType(name, tp) is considered a subtype of tp
|
|
by static type checkers. At runtime, NewType(name, tp) returns
|
|
a dummy function that simply returns its argument. Usage::
|
|
|
|
UserId = NewType('UserId', int)
|
|
|
|
def name_by_id(user_id: UserId) -> str:
|
|
...
|
|
|
|
UserId('user') # Fails type check
|
|
|
|
name_by_id(42) # Fails type check
|
|
name_by_id(UserId(42)) # OK
|
|
|
|
num = UserId(5) + 1 # type: int
|
|
"""
|
|
|
|
def new_type(x):
|
|
return x
|
|
|
|
new_type.__name__ = name
|
|
new_type.__supertype__ = tp
|
|
return new_type
|
|
|
|
|
|
# Python-version-specific alias (Python 2: unicode; Python 3: str)
|
|
Text = str
|
|
|
|
|
|
# Constant that's True when type checking, but False here.
|
|
TYPE_CHECKING = False
|
|
|
|
|
|
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) -> Optional[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 = _alias(stdlib_re.Pattern, AnyStr)
|
|
Match = _alias(stdlib_re.Match, AnyStr)
|
|
|
|
class re:
|
|
"""Wrapper namespace for re type aliases."""
|
|
|
|
__all__ = ['Pattern', 'Match']
|
|
Pattern = Pattern
|
|
Match = Match
|
|
|
|
|
|
re.__name__ = __name__ + '.re'
|
|
sys.modules[re.__name__] = re
|