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When splitting, avoid making a copy of the string if the split doesn't find 

anything (issue 1538).
This commit is contained in:
Skip Montanaro 2007-12-08 15:33:24 +00:00
parent 546624609e
commit 26015494f2
2 changed files with 45 additions and 11 deletions
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3
Misc/NEWS
View File

@ -12,6 +12,9 @@ What's New in Python 2.6 alpha 1?
Core and builtins
-----------------
- Issue #1538: Avoid copying string in split/rsplit if the split
char is not found.
- Issue #1553: An erroneous __length_hint__ can make list() raise a
SystemError.

53
Objects/stringobject.c
View File

@ -1403,8 +1403,9 @@ static const char *stripformat[] = {"|O:lstrip", "|O:rstrip", "|O:strip"};
#define RSKIP_NONSPACE(s, i) { while (i>=0 && !isspace(Py_CHARMASK(s[i]))) i--; }
Py_LOCAL_INLINE(PyObject *)
split_whitespace(const char *s, Py_ssize_t len, Py_ssize_t maxsplit)
split_whitespace(PyStringObject *self, Py_ssize_t len, Py_ssize_t maxsplit)
{
const char *s = PyString_AS_STRING(self);
Py_ssize_t i, j, count=0;
PyObject *str;
PyObject *list = PyList_New(PREALLOC_SIZE(maxsplit));
@ -1419,6 +1420,13 @@ split_whitespace(const char *s, Py_ssize_t len, Py_ssize_t maxsplit)
if (i==len) break;
j = i; i++;
SKIP_NONSPACE(s, i, len);
if (j == 0 && i == len && PyString_CheckExact(self)) {
/* No whitespace in self, so just use it as list[0] */
Py_INCREF(self);
PyList_SET_ITEM(list, 0, (PyObject *)self);
count++;
break;
}
SPLIT_ADD(s, j, i);
}
@ -1437,8 +1445,9 @@ split_whitespace(const char *s, Py_ssize_t len, Py_ssize_t maxsplit)
}
Py_LOCAL_INLINE(PyObject *)
split_char(const char *s, Py_ssize_t len, char ch, Py_ssize_t maxcount)
split_char(PyStringObject *self, Py_ssize_t len, char ch, Py_ssize_t maxcount)
{
const char *s = PyString_AS_STRING(self);
register Py_ssize_t i, j, count=0;
PyObject *str;
PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
@ -1457,7 +1466,13 @@ split_char(const char *s, Py_ssize_t len, char ch, Py_ssize_t maxcount)
}
}
}
if (i <= len) {
if (i == 0 && count == 0 && PyString_CheckExact(self)) {
/* ch not in self, so just use self as list[0] */
Py_INCREF(self);
PyList_SET_ITEM(list, 0, (PyObject *)self);
count++;
}
else if (i <= len) {
SPLIT_ADD(s, i, len);
}
FIX_PREALLOC_SIZE(list);
@ -1492,7 +1507,7 @@ string_split(PyStringObject *self, PyObject *args)
if (maxsplit < 0)
maxsplit = PY_SSIZE_T_MAX;
if (subobj == Py_None)
return split_whitespace(s, len, maxsplit);
return split_whitespace(self, len, maxsplit);
if (PyString_Check(subobj)) {
sub = PyString_AS_STRING(subobj);
n = PyString_GET_SIZE(subobj);
@ -1509,7 +1524,7 @@ string_split(PyStringObject *self, PyObject *args)
return NULL;
}
else if (n == 1)
return split_char(s, len, sub[0], maxsplit);
return split_char(self, len, sub[0], maxsplit);
list = PyList_New(PREALLOC_SIZE(maxsplit));
if (list == NULL)
@ -1609,8 +1624,9 @@ string_rpartition(PyStringObject *self, PyObject *sep_obj)
}
Py_LOCAL_INLINE(PyObject *)
rsplit_whitespace(const char *s, Py_ssize_t len, Py_ssize_t maxsplit)
rsplit_whitespace(PyStringObject *self, Py_ssize_t len, Py_ssize_t maxsplit)
{
const char *s = PyString_AS_STRING(self);
Py_ssize_t i, j, count=0;
PyObject *str;
PyObject *list = PyList_New(PREALLOC_SIZE(maxsplit));
@ -1625,6 +1641,13 @@ rsplit_whitespace(const char *s, Py_ssize_t len, Py_ssize_t maxsplit)
if (i<0) break;
j = i; i--;
RSKIP_NONSPACE(s, i);
if (j == len-1 && i < 0 && PyString_CheckExact(self)) {
/* No whitespace in self, so just use it as list[0] */
Py_INCREF(self);
PyList_SET_ITEM(list, 0, (PyObject *)self);
count++;
break;
}
SPLIT_ADD(s, i + 1, j + 1);
}
if (i >= 0) {
@ -1645,8 +1668,9 @@ rsplit_whitespace(const char *s, Py_ssize_t len, Py_ssize_t maxsplit)
}
Py_LOCAL_INLINE(PyObject *)
rsplit_char(const char *s, Py_ssize_t len, char ch, Py_ssize_t maxcount)
rsplit_char(PyStringObject *self, Py_ssize_t len, char ch, Py_ssize_t maxcount)
{
const char *s = PyString_AS_STRING(self);
register Py_ssize_t i, j, count=0;
PyObject *str;
PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
@ -1664,7 +1688,13 @@ rsplit_char(const char *s, Py_ssize_t len, char ch, Py_ssize_t maxcount)
}
}
}
if (j >= -1) {
if (i < 0 && count == 0 && PyString_CheckExact(self)) {
/* ch not in self, so just use self as list[0] */
Py_INCREF(self);
PyList_SET_ITEM(list, 0, (PyObject *)self);
count++;
}
else if (j >= -1) {
SPLIT_ADD(s, 0, j + 1);
}
FIX_PREALLOC_SIZE(list);
@ -1691,7 +1721,7 @@ string_rsplit(PyStringObject *self, PyObject *args)
{
Py_ssize_t len = PyString_GET_SIZE(self), n, i, j;
Py_ssize_t maxsplit = -1, count=0;
const char *s = PyString_AS_STRING(self), *sub;
const char *s, *sub;
PyObject *list, *str, *subobj = Py_None;
if (!PyArg_ParseTuple(args, "|On:rsplit", &subobj, &maxsplit))
@ -1699,7 +1729,7 @@ string_rsplit(PyStringObject *self, PyObject *args)
if (maxsplit < 0)
maxsplit = PY_SSIZE_T_MAX;
if (subobj == Py_None)
return rsplit_whitespace(s, len, maxsplit);
return rsplit_whitespace(self, len, maxsplit);
if (PyString_Check(subobj)) {
sub = PyString_AS_STRING(subobj);
n = PyString_GET_SIZE(subobj);
@ -1716,7 +1746,7 @@ string_rsplit(PyStringObject *self, PyObject *args)
return NULL;
}
else if (n == 1)
return rsplit_char(s, len, sub[0], maxsplit);
return rsplit_char(self, len, sub[0], maxsplit);
list = PyList_New(PREALLOC_SIZE(maxsplit));
if (list == NULL)
@ -1725,6 +1755,7 @@ string_rsplit(PyStringObject *self, PyObject *args)
j = len;
i = j - n;
s = PyString_AS_STRING(self);
while ( (i >= 0) && (maxsplit-- > 0) ) {
for (; i>=0; i--) {
if (Py_STRING_MATCH(s, i, sub, n)) {