def is_sorted(iterable, key=lambda x:x, reverse=False, expected_len=None):
' checks if an iterable is sorted (consumes the iterable) '
if reverse:
gen = (key(a) >= key(b) for a,b in pairwise(iterable))
else:
gen = (key(a) <= key(b) for a,b in pairwise(iterable))
# pairwise results in one fewer value
if expected_len is not None:
expected_len -= 1
return counted_all(gen, expected_len=expected_len)
def test_pairwise(self):
l = xrange(3)
self.assertEqual([(0,1), (1,2)], [x for x in pairwise(l)])