Issue #6713: Improve decimal int -> string conversions. Thanks Gawain
Bolton for the suggestion and original patches.
diff --git a/Objects/intobject.c b/Objects/intobject.c
index a0e60e7..8a8972c 100644
--- a/Objects/intobject.c
+++ b/Objects/intobject.c
@@ -436,12 +436,6 @@
return 0;
}
-static PyObject *
-int_repr(PyIntObject *v)
-{
- return _PyInt_Format(v, 10, 0);
-}
-
static int
int_compare(PyIntObject *v, PyIntObject *w)
{
@@ -1113,6 +1107,26 @@
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.
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
@@ -1137,6 +1151,10 @@
assert(base >= 2 && base <= 36);
+ /* Special case base 10, for speed */
+ if (base == 10)
+ return int_to_decimal_string(v);
+
do {
/* I'd use i_divmod, except it doesn't produce the results
I want when n is negative. So just duplicate the salient
@@ -1169,7 +1187,7 @@
*--p = 'x';
*--p = '0';
}
- else if (base != 10) {
+ else {
*--p = '#';
*--p = '0' + base%10;
if (base > 10)
@@ -1341,13 +1359,13 @@
0, /* tp_getattr */
0, /* tp_setattr */
(cmpfunc)int_compare, /* tp_compare */
- (reprfunc)int_repr, /* tp_repr */
+ (reprfunc)int_to_decimal_string, /* tp_repr */
&int_as_number, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
(hashfunc)int_hash, /* tp_hash */
- 0, /* tp_call */
- (reprfunc)int_repr, /* tp_str */
+ 0, /* tp_call */
+ (reprfunc)int_to_decimal_string, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */