| """ |
| Providing iterator functions that are not in all version of Python we support. |
| Where possible, we try to use the system-native version and only fall back to |
| these implementations if necessary. |
| """ |
| |
| import itertools |
| |
| def compat_tee(iterable): |
| """Return two independent iterators from a single iterable. |
| |
| Based on http://www.python.org/doc/2.3.5/lib/itertools-example.html |
| """ |
| # Note: Using a dictionary and a list as the default arguments here is |
| # deliberate and safe in this instance. |
| def gen(next, data={}, cnt=[0]): |
| dpop = data.pop |
| for i in itertools.count(): |
| if i == cnt[0]: |
| item = data[i] = next() |
| cnt[0] += 1 |
| else: |
| item = dpop(i) |
| yield item |
| next = iter(iterable).next |
| return gen(next), gen(next) |
| |
| if hasattr(itertools, 'tee'): |
| tee = itertools.tee |
| else: |
| tee = compat_tee |
