codekingpro/portable-devtools

1from itertools import filterfalse2 3 4def unique_everseen(iterable, key=None):5    "List unique elements, preserving order. Remember all elements ever seen."6    # unique_everseen('AAAABBBCCDAABBB') --> A B C D7    # unique_everseen('ABBCcAD', str.lower) --> A B C D8    seen = set()9    seen_add = seen.add10    if key is None:11        for element in filterfalse(seen.__contains__, iterable):12            seen_add(element)13            yield element14    else:15        for element in iterable:16            k = key(element)17            if k not in seen:18                seen_add(k)19                yield element20 21 22# copied from more_itertools 8.823def always_iterable(obj, base_type=(str, bytes)):24    """If *obj* is iterable, return an iterator over its items::25 26        >>> obj = (1, 2, 3)27        >>> list(always_iterable(obj))28        [1, 2, 3]29 30    If *obj* is not iterable, return a one-item iterable containing *obj*::31 32        >>> obj = 133        >>> list(always_iterable(obj))34        [1]35 36    If *obj* is ``None``, return an empty iterable:37 38        >>> obj = None39        >>> list(always_iterable(None))40        []41 42    By default, binary and text strings are not considered iterable::43 44        >>> obj = 'foo'45        >>> list(always_iterable(obj))46        ['foo']47 48    If *base_type* is set, objects for which ``isinstance(obj, base_type)``49    returns ``True`` won't be considered iterable.50 51        >>> obj = {'a': 1}52        >>> list(always_iterable(obj))  # Iterate over the dict's keys53        ['a']54        >>> list(always_iterable(obj, base_type=dict))  # Treat dicts as a unit55        [{'a': 1}]56 57    Set *base_type* to ``None`` to avoid any special handling and treat objects58    Python considers iterable as iterable:59 60        >>> obj = 'foo'61        >>> list(always_iterable(obj, base_type=None))62        ['f', 'o', 'o']63    """64    if obj is None:65        return iter(())66 67    if (base_type is not None) and isinstance(obj, base_type):68        return iter((obj,))69 70    try:71        return iter(obj)72    except TypeError:73        return iter((obj,))74