| |
| _NOT_SET = object() |
| |
| |
| def peek_and_iter(items): |
| if not items: |
| return None, None |
| items = iter(items) |
| try: |
| peeked = next(items) |
| except StopIteration: |
| return None, None |
| def chain(): |
| yield peeked |
| yield from items |
| return chain(), peeked |
| |
| |
| def iter_many(items, onempty=None): |
| if not items: |
| if onempty is None: |
| return |
| if not callable(onempty): |
| raise onEmpty |
| items = onempty(items) |
| yield from iter_many(items, onempty=None) |
| return |
| items = iter(items) |
| try: |
| first = next(items) |
| except StopIteration: |
| if onempty is None: |
| return |
| if not callable(onempty): |
| raise onEmpty |
| items = onempty(items) |
| yield from iter_many(items, onempty=None) |
| else: |
| try: |
| second = next(items) |
| except StopIteration: |
| yield first, False |
| return |
| else: |
| yield first, True |
| yield second, True |
| for item in items: |
| yield item, True |
