traverseda
/
cpython
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Issue #6713: Improve decimal int -> string conversions. Thanks Gawain 

Bolton for the suggestion and original patches.
This commit is contained in:
Mark Dickinson 2009-09-27 16:05:21 +00:00
parent 4780c9a0e0
commit 4b9d473d0a
2 changed files with 30 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
Misc/NEWS
View File

@ -18,7 +18,8 @@ Core and Builtins
- Issue #6922: Fix an infinite loop when trying to decode an invalid - Issue #6922: Fix an infinite loop when trying to decode an invalid
UTF-32 stream with a non-raising error handler like "replace" or "ignore". UTF-32 stream with a non-raising error handler like "replace" or "ignore".
- Issue #6713: Improve performance of integer -> string conversions. - Issue #6713: Improve performance of base 10 int -> string and
long -> string conversions.
- Issue #1590864: Fix potential deadlock when mixing threads and fork(). - Issue #1590864: Fix potential deadlock when mixing threads and fork().

38
Objects/intobject.c
View File

@ -436,12 +436,6 @@ int_print(PyIntObject *v, FILE *fp, int flags)
return 0; return 0;
} }
static PyObject *
int_repr(PyIntObject *v)
{
return _PyInt_Format(v, 10, 0);
}
static int static int
int_compare(PyIntObject *v, PyIntObject *w) int_compare(PyIntObject *v, PyIntObject *w)
{ {
@ -1113,6 +1107,26 @@ int_get1(PyIntObject *v, void *context) {
return PyInt_FromLong(1L); return PyInt_FromLong(1L);
} }
/* Convert an integer to a decimal string. On many platforms, this
will be significantly faster than the general arbitrary-base
conversion machinery in _PyInt_Format, thanks to optimization
opportunities offered by division by a compile-time constant. */
static PyObject *
int_to_decimal_string(PyIntObject *v) {
char buf[sizeof(long)*CHAR_BIT/3+6], *p, *bufend;
long n = v->ob_ival;
unsigned long absn;
p = bufend = buf + sizeof(buf);
absn = n < 0 ? -(unsigned long)n : n;
do {
*--p = '0' + absn % 10;
absn /= 10;
} while (absn);
if (n < 0)
*--p = '-';
return PyString_FromStringAndSize(p, bufend - p);
}
/* Convert an integer to the given base. Returns a string. /* Convert an integer to the given base. Returns a string.
If base is 2, 8 or 16, add the proper prefix '0b', '0o' or '0x'. If base is 2, 8 or 16, add the proper prefix '0b', '0o' or '0x'.
If newstyle is zero, then use the pre-2.6 behavior of octal having If newstyle is zero, then use the pre-2.6 behavior of octal having
@ -1137,6 +1151,10 @@ _PyInt_Format(PyIntObject *v, int base, int newstyle)
assert(base >= 2 && base <= 36); assert(base >= 2 && base <= 36);
/* Special case base 10, for speed */
if (base == 10)
return int_to_decimal_string(v);
do { do {
/* I'd use i_divmod, except it doesn't produce the results /* I'd use i_divmod, except it doesn't produce the results
I want when n is negative. So just duplicate the salient I want when n is negative. So just duplicate the salient
@ -1169,7 +1187,7 @@ _PyInt_Format(PyIntObject *v, int base, int newstyle)
*--p = 'x'; *--p = 'x';
*--p = '0'; *--p = '0';
} }
else if (base != 10) { else {
*--p = '#'; *--p = '#';
*--p = '0' + base%10; *--p = '0' + base%10;
if (base > 10) if (base > 10)
@ -1341,13 +1359,13 @@ PyTypeObject PyInt_Type = {
0, /* tp_getattr */ 0, /* tp_getattr */
0, /* tp_setattr */ 0, /* tp_setattr */
(cmpfunc)int_compare, /* tp_compare */ (cmpfunc)int_compare, /* tp_compare */
(reprfunc)int_repr, /* tp_repr */ (reprfunc)int_to_decimal_string, /* tp_repr */
&int_as_number, /* tp_as_number */ &int_as_number, /* tp_as_number */
0, /* tp_as_sequence */ 0, /* tp_as_sequence */
0, /* tp_as_mapping */ 0, /* tp_as_mapping */
(hashfunc)int_hash, /* tp_hash */ (hashfunc)int_hash, /* tp_hash */
0, /* tp_call */ 0, /* tp_call */
(reprfunc)int_repr, /* tp_str */ (reprfunc)int_to_decimal_string, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */ PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */ 0, /* tp_setattro */
0, /* tp_as_buffer */ 0, /* tp_as_buffer */