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+"""Defines experimental API for runtime inspection of types defined
+in the standard "typing" module.
+
+Example usage::
+ from typing_inspect import is_generic_type
+"""
+
+# NOTE: This module must support Python 2.7 in addition to Python 3.x
+
+import sys
+import types
+import typing
+import typing_extensions
+
+from mypy_extensions import _TypedDictMeta as _TypedDictMeta_Mypy
+
+# See comments in typing_extensions source on why the switch is at 3.9.2
+if (3, 4, 0) <= sys.version_info[:3] < (3, 9, 2):
+ from typing_extensions import _TypedDictMeta as _TypedDictMeta_TE
+elif sys.version_info[:3] >= (3, 9, 2):
+ # Situation with typing_extensions.TypedDict is complicated.
+ # Use the one defined in typing_extentions, and if there is none,
+ # fall back to typing.
+ try:
+ from typing_extensions import _TypedDictMeta as _TypedDictMeta_TE
+ except ImportError:
+ from typing import _TypedDictMeta as _TypedDictMeta_TE
+else:
+ # typing_extensions.TypedDict is a re-export from typing.
+ from typing import TypedDict
+ _TypedDictMeta_TE = type(TypedDict)
+
+NEW_TYPING = sys.version_info[:3] >= (3, 7, 0) # PEP 560
+if NEW_TYPING:
+ import collections.abc
+
+WITH_FINAL = True
+WITH_LITERAL = True
+WITH_CLASSVAR = True
+WITH_NEWTYPE = True
+LEGACY_TYPING = False
+
+if NEW_TYPING:
+ from typing import (
+ Generic, Callable, Union, TypeVar, ClassVar, Tuple, _GenericAlias,
+ ForwardRef, NewType,
+ )
+ from typing_extensions import Final, Literal
+ if sys.version_info[:3] >= (3, 9, 0):
+ from typing import _SpecialGenericAlias
+ typingGenericAlias = (_GenericAlias, _SpecialGenericAlias, types.GenericAlias)
+ else:
+ typingGenericAlias = (_GenericAlias,)
+else:
+ from typing import (
+ Callable, CallableMeta, Union, Tuple, TupleMeta, TypeVar, GenericMeta,
+ _ForwardRef,
+ )
+ try:
+ from typing import _Union, _ClassVar
+ except ImportError:
+ # support for very old typing module <=3.5.3
+ _Union = type(Union)
+ WITH_CLASSVAR = False
+ LEGACY_TYPING = True
+
+ try: # python 3.6
+ from typing_extensions import _Final
+ except ImportError: # python 2.7
+ try:
+ from typing import _Final
+ except ImportError:
+ WITH_FINAL = False
+
+ try: # python 3.6
+ from typing_extensions import Literal
+ except ImportError: # python 2.7
+ try:
+ from typing import Literal
+ except ImportError:
+ WITH_LITERAL = False
+
+ try: # python < 3.5.2
+ from typing_extensions import NewType
+ except ImportError:
+ try:
+ from typing import NewType
+ except ImportError:
+ WITH_NEWTYPE = False
+
+
+def _gorg(cls):
+ """This function exists for compatibility with old typing versions."""
+ assert isinstance(cls, GenericMeta)
+ if hasattr(cls, '_gorg'):
+ return cls._gorg
+ while cls.__origin__ is not None:
+ cls = cls.__origin__
+ return cls
+
+
+def is_generic_type(tp):
+ """Test if the given type is a generic type. This includes Generic itself, but
+ excludes special typing constructs such as Union, Tuple, Callable, ClassVar.
+ Examples::
+
+ is_generic_type(int) == False
+ is_generic_type(Union[int, str]) == False
+ is_generic_type(Union[int, T]) == False
+ is_generic_type(ClassVar[List[int]]) == False
+ is_generic_type(Callable[..., T]) == False
+
+ is_generic_type(Generic) == True
+ is_generic_type(Generic[T]) == True
+ is_generic_type(Iterable[int]) == True
+ is_generic_type(Mapping) == True
+ is_generic_type(MutableMapping[T, List[int]]) == True
+ is_generic_type(Sequence[Union[str, bytes]]) == True
+ """
+ if NEW_TYPING:
+ return (isinstance(tp, type) and issubclass(tp, Generic) or
+ isinstance(tp, typingGenericAlias) and
+ tp.__origin__ not in (Union, tuple, ClassVar, collections.abc.Callable))
+ return (isinstance(tp, GenericMeta) and not
+ isinstance(tp, (CallableMeta, TupleMeta)))
+
+
+def is_callable_type(tp):
+ """Test if the type is a generic callable type, including subclasses
+ excluding non-generic types and callables.
+ Examples::
+
+ is_callable_type(int) == False
+ is_callable_type(type) == False
+ is_callable_type(Callable) == True
+ is_callable_type(Callable[..., int]) == True
+ is_callable_type(Callable[[int, int], Iterable[str]]) == True
+ class MyClass(Callable[[int], int]):
+ ...
+ is_callable_type(MyClass) == True
+
+ For more general tests use callable(), for more precise test
+ (excluding subclasses) use::
+
+ get_origin(tp) is collections.abc.Callable # Callable prior to Python 3.7
+ """
+ if NEW_TYPING:
+ return (tp is Callable or isinstance(tp, typingGenericAlias) and
+ tp.__origin__ is collections.abc.Callable or
+ isinstance(tp, type) and issubclass(tp, Generic) and
+ issubclass(tp, collections.abc.Callable))
+ return type(tp) is CallableMeta
+
+
+def is_tuple_type(tp):
+ """Test if the type is a generic tuple type, including subclasses excluding
+ non-generic classes.
+ Examples::
+
+ is_tuple_type(int) == False
+ is_tuple_type(tuple) == False
+ is_tuple_type(Tuple) == True
+ is_tuple_type(Tuple[str, int]) == True
+ class MyClass(Tuple[str, int]):
+ ...
+ is_tuple_type(MyClass) == True
+
+ For more general tests use issubclass(..., tuple), for more precise test
+ (excluding subclasses) use::
+
+ get_origin(tp) is tuple # Tuple prior to Python 3.7
+ """
+ if NEW_TYPING:
+ return (tp is Tuple or isinstance(tp, typingGenericAlias) and
+ tp.__origin__ is tuple or
+ isinstance(tp, type) and issubclass(tp, Generic) and
+ issubclass(tp, tuple))
+ return type(tp) is TupleMeta
+
+
+def is_optional_type(tp):
+ """Test if the type is type(None), or is a direct union with it, such as Optional[T].
+
+ NOTE: this method inspects nested `Union` arguments but not `TypeVar` definition
+ bounds and constraints. So it will return `False` if
+ - `tp` is a `TypeVar` bound, or constrained to, an optional type
+ - `tp` is a `Union` to a `TypeVar` bound or constrained to an optional type,
+ - `tp` refers to a *nested* `Union` containing an optional type or one of the above.
+
+ Users wishing to check for optionality in types relying on type variables might wish
+ to use this method in combination with `get_constraints` and `get_bound`
+ """
+
+ if tp is type(None): # noqa
+ return True
+ elif is_union_type(tp):
+ return any(is_optional_type(tt) for tt in get_args(tp, evaluate=True))
+ else:
+ return False
+
+
+def is_final_type(tp):
+ """Test if the type is a final type. Examples::
+
+ is_final_type(int) == False
+ is_final_type(Final) == True
+ is_final_type(Final[int]) == True
+ """
+ if NEW_TYPING:
+ return (tp is Final or
+ isinstance(tp, typingGenericAlias) and tp.__origin__ is Final)
+ return WITH_FINAL and type(tp) is _Final
+
+
+try:
+ MaybeUnionType = types.UnionType
+except AttributeError:
+ MaybeUnionType = None
+
+
+def is_union_type(tp):
+ """Test if the type is a union type. Examples::
+
+ is_union_type(int) == False
+ is_union_type(Union) == True
+ is_union_type(Union[int, int]) == False
+ is_union_type(Union[T, int]) == True
+ is_union_type(int | int) == False
+ is_union_type(T | int) == True
+ """
+ if NEW_TYPING:
+ return (tp is Union or
+ (isinstance(tp, typingGenericAlias) and tp.__origin__ is Union) or
+ (MaybeUnionType and isinstance(tp, MaybeUnionType)))
+ return type(tp) is _Union
+
+
+LITERALS = {Literal}
+if hasattr(typing, "Literal"):
+ LITERALS.add(typing.Literal)
+
+
+def is_literal_type(tp):
+ if NEW_TYPING:
+ return (tp in LITERALS or
+ isinstance(tp, typingGenericAlias) and tp.__origin__ in LITERALS)
+ return WITH_LITERAL and type(tp) is type(Literal)
+
+
+def is_typevar(tp):
+ """Test if the type represents a type variable. Examples::
+
+ is_typevar(int) == False
+ is_typevar(T) == True
+ is_typevar(Union[T, int]) == False
+ """
+
+ return type(tp) is TypeVar
+
+
+def is_classvar(tp):
+ """Test if the type represents a class variable. Examples::
+
+ is_classvar(int) == False
+ is_classvar(ClassVar) == True
+ is_classvar(ClassVar[int]) == True
+ is_classvar(ClassVar[List[T]]) == True
+ """
+ if NEW_TYPING:
+ return (tp is ClassVar or
+ isinstance(tp, typingGenericAlias) and tp.__origin__ is ClassVar)
+ elif WITH_CLASSVAR:
+ return type(tp) is _ClassVar
+ else:
+ return False
+
+
+def is_new_type(tp):
+ """Tests if the type represents a distinct type. Examples::
+
+ is_new_type(int) == False
+ is_new_type(NewType) == True
+ is_new_type(NewType('Age', int)) == True
+ is_new_type(NewType('Scores', List[Dict[str, float]])) == True
+ """
+ if not WITH_NEWTYPE:
+ return False
+ elif sys.version_info[:3] >= (3, 10, 0) and sys.version_info.releaselevel != 'beta':
+ return (tp in (NewType, typing_extensions.NewType) or
+ isinstance(tp, (NewType, typing_extensions.NewType)))
+ elif sys.version_info[:3] >= (3, 0, 0):
+ try:
+ res = isinstance(tp, typing_extensions.NewType)
+ except TypeError:
+ pass
+ else:
+ if res:
+ return res
+ return (tp in (NewType, typing_extensions.NewType) or
+ (getattr(tp, '__supertype__', None) is not None and
+ getattr(tp, '__qualname__', '') == 'NewType.<locals>.new_type' and
+ tp.__module__ in ('typing', 'typing_extensions')))
+ else: # python 2
+ # __qualname__ is not available in python 2, so we simplify the test here
+ return (tp is NewType or
+ (getattr(tp, '__supertype__', None) is not None and
+ tp.__module__ in ('typing', 'typing_extensions')))
+
+
+def is_forward_ref(tp):
+ """Tests if the type is a :class:`typing.ForwardRef`. Examples::
+
+ u = Union["Milk", Way]
+ args = get_args(u)
+ is_forward_ref(args[0]) == True
+ is_forward_ref(args[1]) == False
+ """
+ if not NEW_TYPING:
+ return isinstance(tp, _ForwardRef)
+ return isinstance(tp, ForwardRef)
+
+
+def get_last_origin(tp):
+ """Get the last base of (multiply) subscripted type. Supports generic types,
+ Union, Callable, and Tuple. Returns None for unsupported types.
+ Examples::
+
+ get_last_origin(int) == None
+ get_last_origin(ClassVar[int]) == None
+ get_last_origin(Generic[T]) == Generic
+ get_last_origin(Union[T, int][str]) == Union[T, int]
+ get_last_origin(List[Tuple[T, T]][int]) == List[Tuple[T, T]]
+ get_last_origin(List) == List
+ """
+ if NEW_TYPING:
+ raise ValueError('This function is only supported in Python 3.6,'
+ ' use get_origin instead')
+ sentinel = object()
+ origin = getattr(tp, '__origin__', sentinel)
+ if origin is sentinel:
+ return None
+ if origin is None:
+ return tp
+ return origin
+
+
+def get_origin(tp):
+ """Get the unsubscripted version of a type. Supports generic types, Union,
+ Callable, and Tuple. Returns None for unsupported types. Examples::
+
+ get_origin(int) == None
+ get_origin(ClassVar[int]) == None
+ get_origin(Generic) == Generic
+ get_origin(Generic[T]) == Generic
+ get_origin(Union[T, int]) == Union
+ get_origin(List[Tuple[T, T]][int]) == list # List prior to Python 3.7
+ """
+ if NEW_TYPING:
+ if isinstance(tp, typingGenericAlias):
+ return tp.__origin__ if tp.__origin__ is not ClassVar else None
+ if tp is Generic:
+ return Generic
+ return None
+ if isinstance(tp, GenericMeta):
+ return _gorg(tp)
+ if is_union_type(tp):
+ return Union
+ if is_tuple_type(tp):
+ return Tuple
+ if is_literal_type(tp):
+ if NEW_TYPING:
+ return tp.__origin__ or tp
+ return Literal
+
+ return None
+
+
+def get_parameters(tp):
+ """Return type parameters of a parameterizable type as a tuple
+ in lexicographic order. Parameterizable types are generic types,
+ unions, tuple types and callable types. Examples::
+
+ get_parameters(int) == ()
+ get_parameters(Generic) == ()
+ get_parameters(Union) == ()
+ get_parameters(List[int]) == ()
+
+ get_parameters(Generic[T]) == (T,)
+ get_parameters(Tuple[List[T], List[S_co]]) == (T, S_co)
+ get_parameters(Union[S_co, Tuple[T, T]][int, U]) == (U,)
+ get_parameters(Mapping[T, Tuple[S_co, T]]) == (T, S_co)
+ """
+ if LEGACY_TYPING:
+ # python <= 3.5.2
+ if is_union_type(tp):
+ params = []
+ for arg in (tp.__union_params__ if tp.__union_params__ is not None else ()):
+ params += get_parameters(arg)
+ return tuple(params)
+ elif is_tuple_type(tp):
+ params = []
+ for arg in (tp.__tuple_params__ if tp.__tuple_params__ is not None else ()):
+ params += get_parameters(arg)
+ return tuple(params)
+ elif is_generic_type(tp):
+ params = []
+ base_params = tp.__parameters__
+ if base_params is None:
+ return ()
+ for bp_ in base_params:
+ for bp in (get_args(bp_) if is_tuple_type(bp_) else (bp_,)):
+ 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:
+ return tuple(params)
+ else:
+ return ()
+ else:
+ return ()
+ elif NEW_TYPING:
+ if (
+ (
+ isinstance(tp, typingGenericAlias) and
+ hasattr(tp, '__parameters__')
+ ) or
+ isinstance(tp, type) and issubclass(tp, Generic) and
+ tp is not Generic):
+ return tp.__parameters__
+ else:
+ return ()
+ elif (
+ is_generic_type(tp) or is_union_type(tp) or
+ is_callable_type(tp) or is_tuple_type(tp)
+ ):
+ return tp.__parameters__ if tp.__parameters__ is not None else ()
+ else:
+ return ()
+
+
+def get_last_args(tp):
+ """Get last arguments of (multiply) subscripted type.
+ Parameters for Callable are flattened. Examples::
+
+ get_last_args(int) == ()
+ get_last_args(Union) == ()
+ get_last_args(ClassVar[int]) == (int,)
+ get_last_args(Union[T, int]) == (T, int)
+ get_last_args(Iterable[Tuple[T, S]][int, T]) == (int, T)
+ get_last_args(Callable[[T], int]) == (T, int)
+ get_last_args(Callable[[], int]) == (int,)
+ """
+ if NEW_TYPING:
+ raise ValueError('This function is only supported in Python 3.6,'
+ ' use get_args instead')
+ elif is_classvar(tp):
+ return (tp.__type__,) if tp.__type__ is not None else ()
+ elif is_generic_type(tp):
+ try:
+ if tp.__args__ is not None and len(tp.__args__) > 0:
+ return tp.__args__
+ except AttributeError:
+ # python 3.5.1
+ pass
+ return tp.__parameters__ if tp.__parameters__ is not None else ()
+ elif is_union_type(tp):
+ try:
+ return tp.__args__ if tp.__args__ is not None else ()
+ except AttributeError:
+ # python 3.5.2
+ return tp.__union_params__ if tp.__union_params__ is not None else ()
+ elif is_callable_type(tp):
+ return tp.__args__ if tp.__args__ is not None else ()
+ elif is_tuple_type(tp):
+ try:
+ return tp.__args__ if tp.__args__ is not None else ()
+ except AttributeError:
+ # python 3.5.2
+ return tp.__tuple_params__ if tp.__tuple_params__ is not None else ()
+ else:
+ return ()
+
+
+def _eval_args(args):
+ """Internal helper for get_args."""
+ res = []
+ for arg in args:
+ if not isinstance(arg, tuple):
+ res.append(arg)
+ elif is_callable_type(arg[0]):
+ callable_args = _eval_args(arg[1:])
+ if len(arg) == 2:
+ res.append(Callable[[], callable_args[0]])
+ elif arg[1] is Ellipsis:
+ res.append(Callable[..., callable_args[1]])
+ else:
+ res.append(Callable[list(callable_args[:-1]), callable_args[-1]])
+ else:
+ res.append(type(arg[0]).__getitem__(arg[0], _eval_args(arg[1:])))
+ return tuple(res)
+
+
+def get_args(tp, evaluate=None):
+ """Get type arguments with all substitutions performed. For unions,
+ basic simplifications used by Union constructor are performed.
+ On versions prior to 3.7 if `evaluate` is False (default),
+ report result as nested tuple, this matches
+ the internal representation of types. If `evaluate` is True
+ (or if Python version is 3.7 or greater), then all
+ type parameters are applied (this could be time and memory expensive).
+ Examples::
+
+ get_args(int) == ()
+ get_args(Union[int, Union[T, int], str][int]) == (int, str)
+ get_args(Union[int, Tuple[T, int]][str]) == (int, (Tuple, str, int))
+
+ get_args(Union[int, Tuple[T, int]][str], evaluate=True) == \
+ (int, Tuple[str, int])
+ get_args(Dict[int, Tuple[T, T]][Optional[int]], evaluate=True) == \
+ (int, Tuple[Optional[int], Optional[int]])
+ get_args(Callable[[], T][int], evaluate=True) == ([], int,)
+ """
+ if NEW_TYPING:
+ if evaluate is not None and not evaluate:
+ raise ValueError('evaluate can only be True in Python >= 3.7')
+ # Note special aliases on Python 3.9 don't have __args__.
+ if isinstance(tp, typingGenericAlias) and hasattr(tp, '__args__'):
+ res = tp.__args__
+ if get_origin(tp) is collections.abc.Callable and res[0] is not Ellipsis:
+ res = (list(res[:-1]), res[-1])
+ return res
+ if MaybeUnionType and isinstance(tp, MaybeUnionType):
+ return tp.__args__
+ return ()
+ if is_classvar(tp) or is_final_type(tp):
+ return (tp.__type__,) if tp.__type__ is not None else ()
+ if is_literal_type(tp):
+ return tp.__values__ or ()
+ if (
+ is_generic_type(tp) or is_union_type(tp) or
+ is_callable_type(tp) or is_tuple_type(tp)
+ ):
+ try:
+ tree = tp._subs_tree()
+ except AttributeError:
+ # Old python typing module <= 3.5.3
+ if is_union_type(tp):
+ # backport of union's subs_tree
+ tree = _union_subs_tree(tp)
+ elif is_generic_type(tp):
+ # backport of GenericMeta's subs_tree
+ tree = _generic_subs_tree(tp)
+ elif is_tuple_type(tp):
+ # ad-hoc (inspired by union)
+ tree = _tuple_subs_tree(tp)
+ else:
+ # tree = _subs_tree(tp)
+ return ()
+
+ if isinstance(tree, tuple) and len(tree) > 1:
+ if not evaluate:
+ return tree[1:]
+ res = _eval_args(tree[1:])
+ if get_origin(tp) is Callable and res[0] is not Ellipsis:
+ res = (list(res[:-1]), res[-1])
+ return res
+
+ return ()
+
+
+def get_bound(tp):
+ """Return the type bound to a `TypeVar` if any.
+
+ It the type is not a `TypeVar`, a `TypeError` is raised.
+ Examples::
+
+ get_bound(TypeVar('T')) == None
+ get_bound(TypeVar('T', bound=int)) == int
+ """
+
+ if is_typevar(tp):
+ return getattr(tp, '__bound__', None)
+ else:
+ raise TypeError("type is not a `TypeVar`: " + str(tp))
+
+
+def get_constraints(tp):
+ """Returns the constraints of a `TypeVar` if any.
+
+ It the type is not a `TypeVar`, a `TypeError` is raised
+ Examples::
+
+ get_constraints(TypeVar('T')) == ()
+ get_constraints(TypeVar('T', int, str)) == (int, str)
+ """
+
+ if is_typevar(tp):
+ return getattr(tp, '__constraints__', ())
+ else:
+ raise TypeError("type is not a `TypeVar`: " + str(tp))
+
+
+def get_generic_type(obj):
+ """Get the generic type of an object if possible, or runtime class otherwise.
+ Examples::
+
+ class Node(Generic[T]):
+ ...
+ type(Node[int]()) == Node
+ get_generic_type(Node[int]()) == Node[int]
+ get_generic_type(Node[T]()) == Node[T]
+ get_generic_type(1) == int
+ """
+
+ gen_type = getattr(obj, '__orig_class__', None)
+ return gen_type if gen_type is not None else type(obj)
+
+
+def get_generic_bases(tp):
+ """Get generic base types of a type or empty tuple if not possible.
+ Example::
+
+ class MyClass(List[int], Mapping[str, List[int]]):
+ ...
+ MyClass.__bases__ == (List, Mapping)
+ get_generic_bases(MyClass) == (List[int], Mapping[str, List[int]])
+ """
+ if LEGACY_TYPING:
+ return tuple(t for t in tp.__bases__ if isinstance(t, GenericMeta))
+ else:
+ return getattr(tp, '__orig_bases__', ())
+
+
+def typed_dict_keys(td):
+ """If td is a TypedDict class, return a dictionary mapping the typed keys to types.
+ Otherwise, return None. Examples::
+
+ class TD(TypedDict):
+ x: int
+ y: int
+ class Other(dict):
+ x: int
+ y: int
+
+ typed_dict_keys(TD) == {'x': int, 'y': int}
+ typed_dict_keys(dict) == None
+ typed_dict_keys(Other) == None
+ """
+ if isinstance(td, (_TypedDictMeta_Mypy, _TypedDictMeta_TE)):
+ return td.__annotations__.copy()
+ return None
+
+
+def get_forward_arg(fr):
+ """
+ If fr is a ForwardRef, return the string representation of the forward reference.
+ Otherwise return None. Examples::
+
+ tp = List["FRef"]
+ fr = get_args(tp)[0]
+ get_forward_arg(fr) == "FRef"
+ get_forward_arg(tp) == None
+ """
+ return fr.__forward_arg__ if is_forward_ref(fr) else None
+
+
+# A few functions backported and adapted for the LEGACY_TYPING context, and used above
+
+def _replace_arg(arg, tvars, args):
+ """backport of _replace_arg"""
+ if tvars is None:
+ tvars = []
+ # if hasattr(arg, '_subs_tree') and isinstance(arg, (GenericMeta, _TypingBase)):
+ # return arg._subs_tree(tvars, args)
+ if is_union_type(arg):
+ return _union_subs_tree(arg, tvars, args)
+ if is_tuple_type(arg):
+ return _tuple_subs_tree(arg, tvars, args)
+ if is_generic_type(arg):
+ return _generic_subs_tree(arg, tvars, args)
+ if isinstance(arg, TypeVar):
+ for i, tvar in enumerate(tvars):
+ if arg == tvar:
+ return args[i]
+ return arg
+
+
+def _remove_dups_flatten(parameters):
+ """backport of _remove_dups_flatten"""
+
+ # Flatten out Union[Union[...], ...].
+ params = []
+ for p in parameters:
+ if isinstance(p, _Union): # and p.__origin__ is Union:
+ params.extend(p.__union_params__) # p.__args__)
+ elif isinstance(p, tuple) and len(p) > 0 and p[0] is Union:
+ params.extend(p[1:])
+ else:
+ params.append(p)
+ # 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 object is present it will be sole survivor among proper classes.
+ # Never discard type variables.
+ # (In particular, Union[str, AnyStr] != AnyStr.)
+ all_params = set(params)
+ for t1 in params:
+ if not isinstance(t1, type):
+ continue
+ if any(isinstance(t2, type) and issubclass(t1, t2)
+ for t2 in all_params - {t1}
+ if (not (isinstance(t2, GenericMeta) and
+ get_origin(t2) is not None) and
+ not isinstance(t2, TypeVar))):
+ all_params.remove(t1)
+ return tuple(t for t in params if t in all_params)
+
+
+def _subs_tree(cls, tvars=None, args=None):
+ """backport of typing._subs_tree, adapted for legacy versions """
+ def _get_origin(cls):
+ try:
+ return cls.__origin__
+ except AttributeError:
+ return None
+
+ current = _get_origin(cls)
+ if current is None:
+ if not is_union_type(cls) and not is_tuple_type(cls):
+ return cls
+
+ # Make of chain of origins (i.e. cls -> cls.__origin__)
+ orig_chain = []
+ while _get_origin(current) is not None:
+ orig_chain.append(current)
+ current = _get_origin(current)
+
+ # Replace type variables in __args__ if asked ...
+ tree_args = []
+
+ def _get_args(cls):
+ if is_union_type(cls):
+ cls_args = cls.__union_params__
+ elif is_tuple_type(cls):
+ cls_args = cls.__tuple_params__
+ else:
+ try:
+ cls_args = cls.__args__
+ except AttributeError:
+ cls_args = ()
+ return cls_args if cls_args is not None else ()
+
+ for arg in _get_args(cls):
+ tree_args.append(_replace_arg(arg, tvars, args))
+ # ... then continue replacing down the origin chain.
+ for ocls in orig_chain:
+ new_tree_args = []
+ for arg in _get_args(ocls):
+ new_tree_args.append(_replace_arg(arg, get_parameters(ocls), tree_args))
+ tree_args = new_tree_args
+ return tree_args
+
+
+def _union_subs_tree(tp, tvars=None, args=None):
+ """ backport of Union._subs_tree """
+ if tp is Union:
+ return Union # Nothing to substitute
+ tree_args = _subs_tree(tp, tvars, args)
+ # tree_args = tp.__union_params__ if tp.__union_params__ is not None else ()
+ tree_args = _remove_dups_flatten(tree_args)
+ if len(tree_args) == 1:
+ return tree_args[0] # Union of a single type is that type
+ return (Union,) + tree_args
+
+
+def _generic_subs_tree(tp, tvars=None, args=None):
+ """ backport of GenericMeta._subs_tree """
+ if tp.__origin__ is None:
+ return tp
+ tree_args = _subs_tree(tp, tvars, args)
+ return (_gorg(tp),) + tuple(tree_args)
+
+
+def _tuple_subs_tree(tp, tvars=None, args=None):
+ """ ad-hoc function (inspired by union) for legacy typing """
+ if tp is Tuple:
+ return Tuple # Nothing to substitute
+ tree_args = _subs_tree(tp, tvars, args)
+ return (Tuple,) + tuple(tree_args)
+
+
+def _has_type_var(t):
+ if t is None:
+ return False
+ elif is_union_type(t):
+ return _union_has_type_var(t)
+ elif is_tuple_type(t):
+ return _tuple_has_type_var(t)
+ elif is_generic_type(t):
+ return _generic_has_type_var(t)
+ elif is_callable_type(t):
+ return _callable_has_type_var(t)
+ else:
+ return False
+
+
+def _union_has_type_var(tp):
+ if tp.__union_params__:
+ for t in tp.__union_params__:
+ if _has_type_var(t):
+ return True
+ return False
+
+
+def _tuple_has_type_var(tp):
+ if tp.__tuple_params__:
+ for t in tp.__tuple_params__:
+ if _has_type_var(t):
+ return True
+ return False
+
+
+def _callable_has_type_var(tp):
+ if tp.__args__:
+ for t in tp.__args__:
+ if _has_type_var(t):
+ return True
+ return _has_type_var(tp.__result__)
+
+
+def _generic_has_type_var(tp):
+ if tp.__parameters__:
+ for t in tp.__parameters__:
+ if _has_type_var(t):
+ return True
+ return False