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The other half of Issue #1580: use short float repr where possible.

Browse source 
Addresses the float -> string conversion, using David Gay's code which
was added in Mark Dickinson's checkin r71663.

Also addresses these, which are intertwined with the short repr
changes:

- Issue #5772: format(1e100, '<') produces '1e+100', not '1.0e+100'
- Issue #5515: 'n' formatting with commas no longer works poorly
    with leading zeros.
- PEP 378 Format Specifier for Thousands Separator: implemented
    for floats.
This commit is contained in:
Eric Smith 2009-04-16 20:16:10 +00:00
parent b08a53a99d
commit 0923d1d8d7
16 changed files with 1491 additions and 830 deletions
Download patch file Download diff file Expand all files Collapse all files

145
Objects/floatobject.c
View file

@ -197,8 +197,7 @@ PyFloat_FromString(PyObject *v)
sp = s;
/* We don't care about overflow or underflow. If the platform supports
* them, infinities and signed zeroes (on underflow) are fine.
* However, strtod can return 0 for denormalized numbers, where atof
* does not. So (alas!) we special-case a zero result. Note that
* However, strtod can return 0 for denormalized numbers. Note that
* whether strtod sets errno on underflow is not defined, so we can't
* key off errno.
*/
@ -259,14 +258,6 @@ PyFloat_FromString(PyObject *v)
"null byte in argument for float()");
goto error;
}
if (x == 0.0) {
/* See above -- may have been strtod being anal
about denorms. */
PyFPE_START_PROTECT("atof", goto error)
x = PyOS_ascii_atof(s);
PyFPE_END_PROTECT(x)
errno = 0; /* whether atof ever set errno is undefined */
}
result = PyFloat_FromDouble(x);
error:
if (s_buffer)
@ -320,72 +311,6 @@ PyFloat_AsDouble(PyObject *op)
return val;
}
/* Methods */
static void
format_double(char *buf, size_t buflen, double ob_fval, int precision)
{
register char *cp;
char format[32];
int i;
/* Subroutine for float_repr, float_str and float_print.
We want float numbers to be recognizable as such,
i.e., they should contain a decimal point or an exponent.
However, %g may print the number as an integer;
in such cases, we append ".0" to the string. */
PyOS_snprintf(format, 32, "%%.%ig", precision);
PyOS_ascii_formatd(buf, buflen, format, ob_fval);
cp = buf;
if (*cp == '-')
cp++;
for (; *cp != '\0'; cp++) {
/* Any non-digit means it's not an integer;
this takes care of NAN and INF as well. */
if (!isdigit(Py_CHARMASK(*cp)))
break;
}
if (*cp == '\0') {
*cp++ = '.';
*cp++ = '0';
*cp++ = '\0';
return;
}
/* Checking the next three chars should be more than enough to
* detect inf or nan, even on Windows. We check for inf or nan
* at last because they are rare cases.
*/
for (i=0; *cp != '\0' && i<3; cp++, i++) {
if (isdigit(Py_CHARMASK(*cp)) || *cp == '.')
continue;
/* found something that is neither a digit nor point
* it might be a NaN or INF
*/
#ifdef Py_NAN
if (Py_IS_NAN(ob_fval)) {
strcpy(buf, "nan");
}
else
#endif
if (Py_IS_INFINITY(ob_fval)) {
cp = buf;
if (*cp == '-')
cp++;
strcpy(cp, "inf");
}
break;
}
}
static void
format_float(char *buf, size_t buflen, PyFloatObject *v, int precision)
{
assert(PyFloat_Check(v));
format_double(buf, buflen, PyFloat_AS_DOUBLE(v), precision);
}
/* Macro and helper that convert PyObject obj to a C double and store
the value in dbl. If conversion to double raises an exception, obj is
set to NULL, and the function invoking this macro returns NULL. If
@ -398,6 +323,8 @@ format_float(char *buf, size_t buflen, PyFloatObject *v, int precision)
else if (convert_to_double(&(obj), &(dbl)) < 0) \
return obj;
/* Methods */
static int
convert_to_double(PyObject **v, double *dbl)
{
@ -418,38 +345,30 @@ convert_to_double(PyObject **v, double *dbl)
return 0;
}
/* Precisions used by repr() and str(), respectively.
The repr() precision (17 significant decimal digits) is the minimal number
that is guaranteed to have enough precision so that if the number is read
back in the exact same binary value is recreated. This is true for IEEE
floating point by design, and also happens to work for all other modern
hardware.
The str() precision is chosen so that in most cases, the rounding noise
created by various operations is suppressed, while giving plenty of
precision for practical use.
*/
#define PREC_REPR 17
#define PREC_STR 12
static PyObject *
float_str_or_repr(PyFloatObject *v, char format_code)
{
PyObject *result;
char *buf = PyOS_double_to_string(PyFloat_AS_DOUBLE(v),
format_code, 0, Py_DTSF_ADD_DOT_0,
NULL);
if (!buf)
return PyErr_NoMemory();
result = PyUnicode_FromString(buf);
PyMem_Free(buf);
return result;
}
static PyObject *
float_repr(PyFloatObject *v)
{
char buf[100];
format_float(buf, sizeof(buf), v, PREC_REPR);
return PyUnicode_FromString(buf);
return float_str_or_repr(v, 'r');
}
static PyObject *
float_str(PyFloatObject *v)
{
char buf[100];
format_float(buf, sizeof(buf), v, PREC_STR);
return PyUnicode_FromString(buf);
return float_str_or_repr(v, 's');
}
/* Comparison is pretty much a nightmare. When comparing float to float,
@ -1980,15 +1899,21 @@ PyFloat_Fini(void)
i++, p++) {
if (PyFloat_CheckExact(p) &&
Py_REFCNT(p) != 0) {
char buf[100];
format_float(buf, sizeof(buf), p, PREC_STR);
/* XXX(twouters) cast refcount to
long until %zd is universally
available
*/
fprintf(stderr,
char *buf = PyOS_double_to_string(
PyFloat_AS_DOUBLE(p), 'r',
0, 0, NULL);
if (buf) {
/* XXX(twouters) cast
refcount to long
until %zd is
universally
available
*/
fprintf(stderr,
"# <float at %p, refcnt=%ld, val=%s>\n",
p, (long)Py_REFCNT(p), buf);
PyMem_Free(buf);
}
}
}
list = list->next;
@ -2233,14 +2158,6 @@ _PyFloat_Pack8(double x, unsigned char *p, int le)
}
}
/* Should only be used by marshal. */
int
_PyFloat_Repr(double x, char *p, size_t len)
{
format_double(p, len, x, PREC_REPR);
return (int)strlen(p);
}
double
_PyFloat_Unpack4(const unsigned char *p, int le)
{