import functools as _functools
import itertools as _itertools
import typing as _t
from . import left as _left
from ._core.right import Applier as _Applier
from .functional import (compose as _compose,
flip as _flip)
from .iterating import expand as _expand
from .reversal import reverse as _reverse
_T1 = _t.TypeVar('_T1')
_T2 = _t.TypeVar('_T2')
[docs]def accumulator(
_function: _t.Callable[[_T1, _T2], _T2], _initial: _T2
) -> _t.Callable[[_t.Iterable[_T1]], _t.Iterable[_t.Iterable[_T2]]]:
"""
Returns function that yields cumulative results of given binary function
starting from given initial object in direction from right to left.
>>> def to_next_fraction(partial_denominator: int,
... reciprocal: float) -> float:
... return partial_denominator + 1 / reciprocal
>>> to_simple_continued_fractions = accumulator(to_next_fraction, 1)
>>> from itertools import repeat
>>> [round(fraction, 4)
... for fraction in to_simple_continued_fractions(list(repeat(1, 10)))]
[1, 2.0, 1.5, 1.6667, 1.6, 1.625, 1.6154, 1.619, 1.6176, 1.6182, 1.618]
"""
return _t.cast(_t.Callable[[_t.Iterable[_T1]],
_t.Iterable[_t.Iterable[_T2]]],
_compose(_left.accumulator(_flip(_function), _initial),
_reverse))
[docs]def accumulate(_function: _t.Callable[[_T1, _T2], _T2],
_initial: _T2,
_iterable: _t.Iterable[_T1]) -> _t.Iterable[_T2]:
"""
Yields cumulative results of given binary function
starting from given initial object in direction from right to left.
>>> def to_next_fraction(partial_denominator: int,
... reciprocal: float) -> float:
... return partial_denominator + 1 / reciprocal
>>> from itertools import repeat
>>> [round(fraction, 4)
... for fraction in accumulate(to_next_fraction, 1, list(repeat(1, 10)))]
[1, 2.0, 1.5, 1.6667, 1.6, 1.625, 1.6154, 1.619, 1.6176, 1.6182, 1.618]
"""
return _left.accumulate(_flip(_function), _initial, _reverse(_iterable))
[docs]def attacher(_value: _T1) -> _t.Callable[[_t.Iterable[_T1]], _t.Iterable[_T1]]:
"""
Returns function that appends given object to iterable.
>>> attach_hundred = attacher(100)
>>> list(attach_hundred(range(10)))
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 100]
"""
return _t.cast(_t.Callable[[_t.Iterable[_T1]], _t.Iterable[_T1]],
_Applier(attach, _value))
[docs]@_functools.singledispatch
def attach(_iterable: _t.Iterable[_T1], _value: _T1) -> _t.Iterable[_T1]:
"""
Appends given object to the iterable.
"""
yield from _itertools.chain(_iterable, _expand(_value))
@attach.register(list)
def _(_iterable: _t.List[_T1], _value: _T1) -> _t.List[_T1]:
"""
Appends given object to the list.
"""
return _iterable + [_value]
@attach.register(tuple)
def _(_iterable: _t.Tuple[_T1, ...], _value: _T1) -> _t.Tuple[_T1, ...]:
"""
Appends given object to the tuple.
"""
return _iterable + (_value,)
[docs]def folder(_function: _t.Callable[[_T1, _T2], _T2],
_initial: _T2) -> _t.Callable[[_t.Iterable[_T1]], _T2]:
"""
Returns function that cumulatively applies given binary function
starting from given initial object in direction from right to left.
>>> to_sum_evaluation_order = folder('({} + {})'.format, 0)
>>> to_sum_evaluation_order(range(1, 10))
'(1 + (2 + (3 + (4 + (5 + (6 + (7 + (8 + (9 + 0)))))))))'
"""
left_folder = _left.folder(_flip(_function), _initial)
return _t.cast(_t.Callable[[_t.Iterable[_T1]], _T2],
_compose(left_folder, _reverse))
[docs]def fold(_function: _t.Callable[[_T2, _T1], _T2],
_initial: _T2,
_iterable: _t.Iterable[_T1]) -> _T2:
"""
Cumulatively applies given binary function
starting from given initial object in direction from left to right.
>>> fold('({} + {})'.format, 0, range(1, 10))
'(1 + (2 + (3 + (4 + (5 + (6 + (7 + (8 + (9 + 0)))))))))'
"""
return _functools.reduce(_flip(_function), _reverse(_iterable), _initial)
[docs]def applier(_function: _t.Callable[..., _T2],
*args: _t.Any,
**kwargs: _t.Any) -> _t.Callable[..., _T2]:
"""
Returns function that behaves like given function
with given arguments partially applied.
Given positional arguments will be added to the right end.
>>> square = applier(pow, 2)
>>> square(10)
100
"""
return _Applier(_function, *args, **kwargs)