snakeoil.iterables module

Collection of functionality to make using iterators transparently easier

class snakeoil.iterables.caching_iter(iterable, sorter=None)

Bases: object

On demand consumes from an iterable so as to appear like a tuple

>>> from snakeoil.iterables import caching_iter
>>> i = iter(range(5))
>>> ci = caching_iter(i)
>>> print(ci[0])
0
>>> print(ci[2])
2
>>> print(i.next())
3

cached_list

iterable

sorter

class snakeoil.iterables.expandable_chain(*iterables)

Bases: object

chained iterables, with the ability to add new iterables to the chain as long as the instance hasn’t raised StopIteration already. This is fairly useful for implementing queues of things that must be processed.

>>> from snakeoil.iterables import expandable_chain
>>> l = range(5)
>>> i = expandable_chain(l)
>>> print(i.next())
0
>>> print(i.next())
1
>>> i.appendleft(range(5, 7))
>>> print(i.next())
5
>>> print(i.next())
6
>>> print(i.next())
2

append(iterable)

append an iterable to the chain to be consumed

appendleft(iterable)

prepend an iterable to the chain to be consumed

extend(iterables)

extend multiple iterables to the chain to be consumed

extendleft(iterables)

prepend multiple iterables to the chain to be consumed

snakeoil.iterables.iter_sort(sorter, *iterables)

Merge a number of sorted iterables into a single sorted iterable.

Parameters:

• sorter (callable.) – function, passed a list of [element, iterable].

• iterables – iterables to consume from. It’s required that each iterable to consume from is presorted already within that specific iterable.

Returns:

yields items one by one in combined sorted order

For example:

>>> from snakeoil.iterables import iter_sort
>>> iter1 = range(0, 5, 2)
>>> iter2 = range(1, 6, 2)
>>> # note that these lists will be consumed as they go,
>>> # sorted is just being used to compare the individual items
>>> sorted_iter = iter_sort(sorted, iter1, iter2)
>>> print(list(sorted_iter))
[0, 1, 2, 3, 4, 5]

snakeoil.iterables.partition(iterable, predicate=<class 'bool'>)

Partition an iterable into two iterables based on a given filter.

Taking care that the predicate is called only once for each element.

Parameters:

• iterable – target iterable to split into two

• predicate – filtering function used to split the iterable

Returns:

A tuple of iterators, the first containing items that don’t match the filter and the second the matched items.