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needforspeed: partition for 8-bit strings. for some simple tests, 

this is on par with a corresponding find, and nearly twice as fast
as split(sep, 1)

full tests, a unicode version, and documentation will follow to-
morrow.
This commit is contained in:
Fredrik Lundh 2006-05-25 23:27:53 +00:00
parent d89fc22dc6
commit fe5bb7e6d9
1 changed files with 66 additions and 5 deletions
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71
Objects/stringobject.c
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@ -799,8 +799,7 @@ PyString_AsStringAndSize(register PyObject *obj,
#define FAST_SEARCH 1
LOCAL(Py_ssize_t)
fastsearch(const char* s, Py_ssize_t n, const char* p,
Py_ssize_t m, int mode)
fastsearch(const char* s, Py_ssize_t n, const char* p, Py_ssize_t m, int mode)
{
long mask;
int skip, count = 0;
@ -860,10 +859,8 @@ LOCAL(Py_ssize_t)
/* miss: check if next character is part of pattern */
if (!(mask & (1 << (s[i+m] & 0x1F))))
i = i + m;
else {
else
i = i + skip;
continue;
}
} else {
/* skip: check if next character is part of pattern */
if (!(mask & (1 << (s[i+m] & 0x1F))))
@ -1601,6 +1598,68 @@ string_split(PyStringObject *self, PyObject *args)
return NULL;
}
PyDoc_STRVAR(partition__doc__,
"S.partition(sep) -> (head, sep, tail)\n\
\n\
Searches for the separator sep in S, and returns the part before it,\n\
the separator itself, and the part after it. If the separator is not\n\
found, returns S and two empty strings.");
static PyObject *
string_partition(PyStringObject *self, PyObject *args)
{
Py_ssize_t len = PyString_GET_SIZE(self), sep_len, pos;
const char *str = PyString_AS_STRING(self), *sep;
PyObject *sepobj;
PyObject * out;
if (!PyArg_ParseTuple(args, "O:partition", &sepobj))
return NULL;
if (PyString_Check(sepobj)) {
sep = PyString_AS_STRING(sepobj);
sep_len = PyString_GET_SIZE(sepobj);
}
#ifdef Py_USING_UNICODE_NOTYET
else if (PyUnicode_Check(sepobj))
return PyUnicode_Partition((PyObject *)self, sepobj);
#endif
else if (PyObject_AsCharBuffer(sepobj, &sep, &sep_len))
return NULL;
if (sep_len == 0) {
PyErr_SetString(PyExc_ValueError, "empty separator");
return NULL;
}
out = PyTuple_New(3);
if (!out)
return NULL;
pos = fastsearch(str, len, sep, sep_len, FAST_SEARCH);
if (pos < 0) {
Py_INCREF(self);
PyTuple_SET_ITEM(out, 0, (PyObject*) self);
Py_INCREF(nullstring);
PyTuple_SET_ITEM(out, 1, (PyObject*) nullstring);
Py_INCREF(nullstring);
PyTuple_SET_ITEM(out, 2, (PyObject*) nullstring);
} else {
Py_INCREF(sepobj);
PyTuple_SET_ITEM(out, 0, PyString_FromStringAndSize(str, pos));
PyTuple_SET_ITEM(out, 1, sepobj);
PyTuple_SET_ITEM(out, 2,
PyString_FromStringAndSize(str + sep_len + pos,
len - sep_len - pos)
);
if (PyErr_Occurred()) {
Py_DECREF(out);
return NULL;
}
}
return out;
}
static PyObject *
rsplit_whitespace(const char *s, Py_ssize_t len, Py_ssize_t maxsplit)
{
@ -3910,6 +3969,8 @@ string_methods[] = {
{"count", (PyCFunction)string_count, METH_VARARGS, count__doc__},
{"endswith", (PyCFunction)string_endswith, METH_VARARGS,
endswith__doc__},
{"partition", (PyCFunction)string_partition, METH_VARARGS,
partition__doc__},
{"find", (PyCFunction)string_find, METH_VARARGS, find__doc__},
{"index", (PyCFunction)string_index, METH_VARARGS, index__doc__},
{"lstrip", (PyCFunction)string_lstrip, METH_VARARGS, lstrip__doc__},