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When expandtabs() would be a no-op, don't create a duplicate string

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This commit is contained in:
Antoine Pitrou 2011-10-04 16:04:01 +02:00
parent 87a484caf5
commit e19aa388e8
2 changed files with 11 additions and 0 deletions
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4
Lib/test/test_unicode.py
View file

@ -1585,6 +1585,10 @@ class UnicodeTest(string_tests.CommonTest,
return return
self.assertRaises(OverflowError, 't\tt\t'.expandtabs, sys.maxsize) self.assertRaises(OverflowError, 't\tt\t'.expandtabs, sys.maxsize)
def test_expandtabs_optimization(self):
s = 'abc'
self.assertIs(s.expandtabs(), s)
def test_raiseMemError(self): def test_raiseMemError(self):
if struct.calcsize('P') == 8: if struct.calcsize('P') == 8:
# 64 bits pointers # 64 bits pointers

7
Objects/unicodeobject.c
View file

@ -10196,6 +10196,7 @@ unicode_expandtabs(PyUnicodeObject *self, PyObject *args)
void *src_data, *dest_data; void *src_data, *dest_data;
int tabsize = 8; int tabsize = 8;
int kind; int kind;
int found;
if (!PyArg_ParseTuple(args, "|i:expandtabs", &tabsize)) if (!PyArg_ParseTuple(args, "|i:expandtabs", &tabsize))
return NULL; return NULL;
@ -10205,9 +10206,11 @@ unicode_expandtabs(PyUnicodeObject *self, PyObject *args)
i = j = line_pos = 0; i = j = line_pos = 0;
kind = PyUnicode_KIND(self); kind = PyUnicode_KIND(self);
src_data = PyUnicode_DATA(self); src_data = PyUnicode_DATA(self);
found = 0;
for (; i < src_len; i++) { for (; i < src_len; i++) {
ch = PyUnicode_READ(kind, src_data, i); ch = PyUnicode_READ(kind, src_data, i);
if (ch == '\t') { if (ch == '\t') {
found = 1;
if (tabsize > 0) { if (tabsize > 0) {
incr = tabsize - (line_pos % tabsize); /* cannot overflow */ incr = tabsize - (line_pos % tabsize); /* cannot overflow */
if (j > PY_SSIZE_T_MAX - incr) if (j > PY_SSIZE_T_MAX - incr)
@ -10225,6 +10228,10 @@ unicode_expandtabs(PyUnicodeObject *self, PyObject *args)
line_pos = 0; line_pos = 0;
} }
} }
if (!found && PyUnicode_CheckExact(self)) {
Py_INCREF((PyObject *) self);
return (PyObject *) self;
}
/* Second pass: create output string and fill it */ /* Second pass: create output string and fill it */
u = PyUnicode_New(j, PyUnicode_MAX_CHAR_VALUE(self)); u = PyUnicode_New(j, PyUnicode_MAX_CHAR_VALUE(self));