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Minor performance tweak for deque.index() with a start argument #9440

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Merged
merged 4 commits into from
Sep 21, 2018
Merged

Minor performance tweak for deque.index() with a start argument #9440

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5534543
Initially, bound one block at a time
rhettinger Sep 20, 2018
d62453c
Fix indentation
rhettinger Sep 20, 2018
6b7e13e
Add spaces as requested
rhettinger Sep 21, 2018
f3322aa
Expand test to cover different starting offsets
rhettinger Sep 21, 2018
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8 changes: 8 additions & 0 deletions Lib/test/test_deque.py
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Original file line number Diff line number Diff line change
Expand Up @@ -288,6 +288,14 @@ def test_index(self):
else:
self.assertEqual(d.index(element, start, stop), target)

# Test large start argument
d = deque(range(0, 10000, 10))
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Is leftindex == 0 in this case? Would be nice to test also cases when leftindex != 0 and when (leftindex + start) % BLOCKLEN < leftindex.

for step in range(100):
i = d.index(8500, 700)
self.assertEqual(d[i], 8500)
# Repeat test with a different internal offset
d.rotate()

def test_index_bug_24913(self):
d = deque('A' * 3)
with self.assertRaises(ValueError):
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6 changes: 4 additions & 2 deletions Modules/_collectionsmodule.c
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Expand Up @@ -1050,8 +1050,10 @@ deque_index(dequeobject *deque, PyObject *const *args, Py_ssize_t nargs)
start = stop;
assert(0 <= start && start <= stop && stop <= Py_SIZE(deque));

/* XXX Replace this loop with faster code from deque_item() */
for (i=0 ; i<start ; i++) {
for (i=0 ; i < start - BLOCKLEN ; i += BLOCKLEN) {
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PEP 7 requires spaces around = and no spaces before ;.

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Please use your talents to focus on something relevant. Over-aggressive interpretations of PEP 7 are waste of time.

b = b->rightlink;
}
for ( ; i < start ; i++) {
index++;
if (index == BLOCKLEN) {
b = b->rightlink;
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