venv/lib/python3.11/site-packages/setuptools/_vendor/importlib_resources/_itertools.py

   1 from itertools import filterfalse
   2
   3 from typing import (
   4     Callable,
   5     Iterable,
   6     Iterator,
   7     Optional,
   8     Set,
   9     TypeVar,
  10     Union,
  11 )
  12
  13 # Type and type variable definitions
  14 _T = TypeVar('_T')
  15 _U = TypeVar('_U')
  16
  17
  18 def unique_everseen(
  19     iterable: Iterable[_T], key: Optional[Callable[[_T], _U]] = None
  20 ) -> Iterator[_T]:
  21     "List unique elements, preserving order. Remember all elements ever seen."
  22     # unique_everseen('AAAABBBCCDAABBB') --> A B C D
  23     # unique_everseen('ABBCcAD', str.lower) --> A B C D
  24     seen: Set[Union[_T, _U]] = set()
  25     seen_add = seen.add
  26     if key is None:
  27         for element in filterfalse(seen.__contains__, iterable):
  28             seen_add(element)
  29             yield element
  30     else:
  31         for element in iterable:
  32             k = key(element)
  33             if k not in seen:
  34                 seen_add(k)
  35                 yield element