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accu.c
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115 lines (105 loc) · 2.4 KB
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/* Accumulator struct implementation */
#include "Python.h"
#include "accu.h"
static PyObject *
join_list_unicode(PyObject *lst)
{
/* return ''.join(lst) */
PyObject *sep, *ret;
sep = PyUnicode_FromStringAndSize("", 0);
ret = PyUnicode_Join(sep, lst);
Py_DECREF(sep);
return ret;
}
int
_PyAccu_Init(_PyAccu *acc)
{
/* Lazily allocated */
acc->large = NULL;
acc->small = PyList_New(0);
if (acc->small == NULL)
return -1;
return 0;
}
static int
flush_accumulator(_PyAccu *acc)
{
Py_ssize_t nsmall = PyList_GET_SIZE(acc->small);
if (nsmall) {
int ret;
PyObject *joined;
if (acc->large == NULL) {
acc->large = PyList_New(0);
if (acc->large == NULL)
return -1;
}
joined = join_list_unicode(acc->small);
if (joined == NULL)
return -1;
if (PyList_SetSlice(acc->small, 0, nsmall, NULL)) {
Py_DECREF(joined);
return -1;
}
ret = PyList_Append(acc->large, joined);
Py_DECREF(joined);
return ret;
}
return 0;
}
int
_PyAccu_Accumulate(_PyAccu *acc, PyObject *unicode)
{
Py_ssize_t nsmall;
assert(PyUnicode_Check(unicode));
if (PyList_Append(acc->small, unicode))
return -1;
nsmall = PyList_GET_SIZE(acc->small);
/* Each item in a list of unicode objects has an overhead (in 64-bit
* builds) of:
* - 8 bytes for the list slot
* - 56 bytes for the header of the unicode object
* that is, 64 bytes. 100000 such objects waste more than 6MB
* compared to a single concatenated string.
*/
if (nsmall < 100000)
return 0;
return flush_accumulator(acc);
}
PyObject *
_PyAccu_FinishAsList(_PyAccu *acc)
{
int ret;
PyObject *res;
ret = flush_accumulator(acc);
Py_CLEAR(acc->small);
if (ret) {
Py_CLEAR(acc->large);
return NULL;
}
res = acc->large;
acc->large = NULL;
return res;
}
PyObject *
_PyAccu_Finish(_PyAccu *acc)
{
PyObject *list, *res;
if (acc->large == NULL) {
list = acc->small;
acc->small = NULL;
}
else {
list = _PyAccu_FinishAsList(acc);
if (!list)
return NULL;
}
res = join_list_unicode(list);
Py_DECREF(list);
return res;
}
void
_PyAccu_Destroy(_PyAccu *acc)
{
Py_CLEAR(acc->small);
Py_CLEAR(acc->large);
}