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Speedup str[a🅱️step] for step != 1 

Try to stop the scanner of the maximum character before the end using a limit
depending on the kind (e.g. 256 for PyUnicode_2BYTE_KIND).
This commit is contained in:
Victor Stinner 2011-10-05 14:13:28 +02:00
parent ae86485517
commit c80d6d20d5
1 changed files with 23 additions and 3 deletions
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26
Objects/unicodeobject.c
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@ -1520,6 +1520,22 @@ unicode_fromascii(const unsigned char* u, Py_ssize_t size)
return res;
}
static Py_UCS4
kind_maxchar_limit(unsigned int kind)
{
switch(kind) {
case PyUnicode_1BYTE_KIND:
return 0x80;
case PyUnicode_2BYTE_KIND:
return 0x100;
case PyUnicode_4BYTE_KIND:
return 0x10000;
default:
assert(0 && "invalid kind");
return 0x10ffff;
}
}
static PyObject*
_PyUnicode_FromUCS1(const unsigned char* u, Py_ssize_t size)
{
@ -12335,7 +12351,7 @@ unicode_subscript(PyUnicodeObject* self, PyObject* item)
PyObject *result;
void *src_data, *dest_data;
int src_kind, dest_kind;
Py_UCS4 ch, max_char;
Py_UCS4 ch, max_char, kind_limit;
if (PySlice_GetIndicesEx(item, PyUnicode_GET_LENGTH(self),
&start, &stop, &step, &slicelength) < 0) {
@ -12354,13 +12370,17 @@ unicode_subscript(PyUnicodeObject* self, PyObject* item)
start, start + slicelength);
}
/* General case */
max_char = 127;
max_char = 0;
src_kind = PyUnicode_KIND(self);
kind_limit = kind_maxchar_limit(src_kind);
src_data = PyUnicode_DATA(self);
for (cur = start, i = 0; i < slicelength; cur += step, i++) {
ch = PyUnicode_READ(src_kind, src_data, cur);
if (ch > max_char)
if (ch > max_char) {
max_char = ch;
if (max_char >= kind_limit)
break;
}
}
result = PyUnicode_New(slicelength, max_char);
if (result == NULL)