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SF bug #604716: faster [None]*n or []*n

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Fulfilled request to special case repetitions of lists of length 0 or 1.
This commit is contained in:
Raymond Hettinger 2003-05-21 05:58:46 +00:00
parent 28137a09d6
commit 6624e68546
1 changed files with 12 additions and 0 deletions
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12
Objects/listobject.c
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@ -421,14 +421,26 @@ list_repeat(PyListObject *a, int n)
int size;
PyListObject *np;
PyObject **p;
PyObject *elem;
if (n < 0)
n = 0;
size = a->ob_size * n;
if (size == 0)
return PyList_New(0);
if (n && size/n != a->ob_size)
return PyErr_NoMemory();
np = (PyListObject *) PyList_New(size);
if (np == NULL)
return NULL;
if (a->ob_size == 1) {
elem = a->ob_item[0];
for (i = 0; i < n; i++) {
np->ob_item[i] = elem;
Py_INCREF(elem);
}
return (PyObject *) np;
}
p = np->ob_item;
for (i = 0; i < n; i++) {
for (j = 0; j < a->ob_size; j++) {