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list_ass_slice(): The difference between "recycle" and "recycled" was

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impossible to remember, so renamed one to something obvious.  Headed
off potential signed-vs-unsigned compiler complaints I introduced by
changing the type of a vrbl to unsigned.  Removed the need for the
tedious explanation about "backward pointer loops" by looping on an
int instead.
This commit is contained in:
Tim Peters 2004-07-31 02:54:42 +00:00
parent 8d9eb10c29
commit 7357222d0e
1 changed files with 10 additions and 17 deletions
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27
Objects/listobject.c
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@ -528,15 +528,15 @@ list_ass_slice(PyListObject *a, int ilow, int ihigh, PyObject *v)
we must allocate an additional array, 'recycle', into which
we temporarily copy the items that are deleted from the
list. :-( */
PyObject *recycled[8];
PyObject **recycle = recycled; /* will allocate more if needed */
PyObject *recycle_on_stack[8];
PyObject **recycle = recycle_on_stack; /* will allocate more if needed */
PyObject **item;
PyObject **vitem = NULL;
PyObject *v_as_SF = NULL; /* PySequence_Fast(v) */
int n; /* # of elements in replacement list */
int norig; /* # of elements in list getting replaced */
int d; /* Change in size */
int k; /* Loop index */
int k;
size_t s;
int result = -1; /* guilty until proved innocent */
#define b ((PyListObject *)v)
@ -578,7 +578,7 @@ list_ass_slice(PyListObject *a, int ilow, int ihigh, PyObject *v)
item = a->ob_item;
/* recycle the items that we are about to remove */
s = norig * sizeof(PyObject *);
if (s > sizeof(recycled)) {
if (s > sizeof(recycle_on_stack)) {
recycle = (PyObject **)PyMem_MALLOC(s);
if (recycle == NULL) {
PyErr_NoMemory();
@ -594,30 +594,23 @@ list_ass_slice(PyListObject *a, int ilow, int ihigh, PyObject *v)
item = a->ob_item;
}
else if (d > 0) { /* Insert d items */
s = a->ob_size;
if (list_resize(a, s+d) < 0)
k = a->ob_size;
if (list_resize(a, k+d) < 0)
goto Error;
item = a->ob_item;
memmove(&item[ihigh+d], &item[ihigh],
(s - ihigh)*sizeof(PyObject *));
(k - ihigh)*sizeof(PyObject *));
}
for (k = 0; k < n; k++, ilow++) {
PyObject *w = vitem[k];
Py_XINCREF(w);
item[ilow] = w;
}
/* Convoluted: there's some obscure reason for wanting to do
* the decrefs "backwards", but C doesn't guarantee you can compute
* a pointer to one slot *before* an allocated vector. So checking
* for item >= recycle is incorrect.
*/
for (item = recycle + norig; item > recycle; ) {
--item;
Py_XDECREF(*item);
}
for (k = norig - 1; k >= 0; --k)
Py_XDECREF(recycle[k]);
result = 0;
Error:
if (recycle != recycled)
if (recycle != recycle_on_stack)
PyMem_FREE(recycle);
Py_XDECREF(v_as_SF);
return result;