diff --git a/test/test_utils.py b/test/test_utils.py index 4bfe250ac9..f73e7b2048 100644 --- a/test/test_utils.py +++ b/test/test_utils.py @@ -1537,8 +1537,11 @@ def test_LazyList(self): self.assertEqual(LazyList(it).exhaust(), it) self.assertEqual(LazyList(it)[5], it[5]) + self.assertEqual(LazyList(it)[5:], it[5:]) + self.assertEqual(LazyList(it)[:5], it[:5]) self.assertEqual(LazyList(it)[::2], it[::2]) self.assertEqual(LazyList(it)[1::2], it[1::2]) + self.assertEqual(LazyList(it)[5::-1], it[5::-1]) self.assertEqual(LazyList(it)[6:2:-2], it[6:2:-2]) self.assertEqual(LazyList(it)[::-1], it[::-1]) @@ -1550,6 +1553,7 @@ def test_LazyList(self): self.assertEqual(list(LazyList(it).reverse()), it[::-1]) self.assertEqual(list(LazyList(it).reverse()[1:3:7]), it[::-1][1:3:7]) + self.assertEqual(list(LazyList(it).reverse()[::-1]), it) def test_LazyList_laziness(self): diff --git a/yt_dlp/utils.py b/yt_dlp/utils.py index 998689efe4..4f584596d1 100644 --- a/yt_dlp/utils.py +++ b/yt_dlp/utils.py @@ -3993,28 +3993,27 @@ def exhaust(self): @staticmethod def __reverse_index(x): - return -(x + 1) + return None if x is None else -(x + 1) def __getitem__(self, idx): if isinstance(idx, slice): - step = idx.step or 1 - start = idx.start if idx.start is not None else 0 if step > 0 else -1 - stop = idx.stop if idx.stop is not None else -1 if step > 0 else 0 if self.__reversed: - (start, stop), step = map(self.__reverse_index, (start, stop)), -step - idx = slice(start, stop, step) + idx = slice(self.__reverse_index(idx.start), self.__reverse_index(idx.stop), -(idx.step or 1)) + start, stop, step = idx.start, idx.stop, idx.step or 1 elif isinstance(idx, int): if self.__reversed: idx = self.__reverse_index(idx) - start = stop = idx + start, stop, step = idx, idx, 0 else: raise TypeError('indices must be integers or slices') - if start < 0 or stop < 0: + if ((start or 0) < 0 or (stop or 0) < 0 + or (start is None and step < 0) + or (stop is None and step > 0)): # We need to consume the entire iterable to be able to slice from the end # Obviously, never use this with infinite iterables return self.__exhaust()[idx] - n = max(start, stop) - len(self.__cache) + 1 + n = max(start or 0, stop or 0) - len(self.__cache) + 1 if n > 0: self.__cache.extend(itertools.islice(self.__iterable, n)) return self.__cache[idx]