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gh-102088 Optimize iter_index itertools recipe #102360

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Merged
merged 2 commits into from
Mar 2, 2023
Merged

gh-102088 Optimize iter_index itertools recipe #102360

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148bde6
Optimize iter_index itertools recipe
pochmann Mar 1, 2023
0b0b81c
Add test for operator.indexOf on iterators
pochmann Mar 1, 2023
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9 changes: 6 additions & 3 deletions Doc/library/itertools.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -886,9 +886,12 @@ which incur interpreter overhead.
except AttributeError:
# Slow path for general iterables
it = islice(iterable, start, None)
for i, element in enumerate(it, start):
if element is value or element == value:
yield i
i = start - 1
try:
while True:
yield (i := i + operator.indexOf(it, value) + 1)
except ValueError:
pass
else:
# Fast path for sequences
i = start - 1
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3 changes: 3 additions & 0 deletions Lib/test/test_operator.py
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Expand Up @@ -208,6 +208,9 @@ def test_indexOf(self):
nan = float("nan")
self.assertEqual(operator.indexOf([nan, nan, 21], nan), 0)
self.assertEqual(operator.indexOf([{}, 1, {}, 2], {}), 0)
it = iter('leave the iterator at exactly the position after the match')
self.assertEqual(operator.indexOf(it, 'a'), 2)
self.assertEqual(next(it), 'v')

def test_invert(self):
operator = self.module
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