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Add popitem() -- SF patch #102733.

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This commit is contained in:
Guido van Rossum 2000-12-12 22:02:18 +00:00
parent 968c36d81b
commit ba6ab84e73
1 changed files with 53 additions and 0 deletions
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53
Objects/dictobject.c
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@ -1132,6 +1132,58 @@ dict_clear(register dictobject *mp, PyObject *args)
return Py_None;
}
static PyObject *
dict_popitem(dictobject *mp, PyObject *args)
{
int i = 0;
dictentry *ep;
PyObject *res;
if (!PyArg_NoArgs(args))
return NULL;
if (mp->ma_used == 0) {
PyErr_SetString(PyExc_KeyError,
"popitem(): dictionary is empty");
return NULL;
}
/* Set ep to "the first" dict entry with a value. We abuse the hash
* field of slot 0 to hold a search finger:
* If slot 0 has a value, use slot 0.
* Else slot 0 is being used to hold a search finger,
* and we use its hash value as the first index to look.
*/
ep = &mp->ma_table[0];
if (ep->me_value == NULL) {
i = (int)ep->me_hash;
/* The hash field may be uninitialized trash, or it
* may be a real hash value, or it may be a legit
* search finger, or it may be a once-legit search
* finger that's out of bounds now because it
* wrapped around or the table shrunk -- simply
* make sure it's in bounds now.
*/
if (i >= mp->ma_size || i < 1)
i = 1; /* skip slot 0 */
while ((ep = &mp->ma_table[i])->me_value == NULL) {
i++;
if (i >= mp->ma_size)
i = 1;
}
}
res = PyTuple_New(2);
if (res != NULL) {
PyTuple_SET_ITEM(res, 0, ep->me_key);
PyTuple_SET_ITEM(res, 1, ep->me_value);
Py_INCREF(dummy);
ep->me_key = dummy;
ep->me_value = NULL;
mp->ma_used--;
assert(mp->ma_table[0].me_value == NULL);
mp->ma_table[0].me_hash = i + 1; /* next place to start */
}
return res;
}
static int
dict_traverse(PyObject *op, visitproc visit, void *arg)
{
@ -1167,6 +1219,7 @@ static PyMethodDef mapp_methods[] = {
{"copy", (PyCFunction)dict_copy},
{"get", (PyCFunction)dict_get, METH_VARARGS},
{"setdefault", (PyCFunction)dict_setdefault, METH_VARARGS},
{"popitem", (PyCFunction)dict_popitem},
{NULL, NULL} /* sentinel */
};