[Python-checkins] r72109 - in python/branches/py3k: Lib/test/formatfloat_testcases.txt Lib/test/test_float.py Misc/NEWS Python/pystrtod.c
mark.dickinson
python-checkins at python.org
Wed Apr 29 20:47:07 CEST 2009
Author: mark.dickinson
Date: Wed Apr 29 20:47:07 2009
New Revision: 72109
Log:
Issue #5864: Fix problem with empty code formatting for floats,
where a bogus trailing zero could be added.
Modified:
python/branches/py3k/Lib/test/formatfloat_testcases.txt
python/branches/py3k/Lib/test/test_float.py
python/branches/py3k/Misc/NEWS
python/branches/py3k/Python/pystrtod.c
Modified: python/branches/py3k/Lib/test/formatfloat_testcases.txt
==============================================================================
--- python/branches/py3k/Lib/test/formatfloat_testcases.txt (original)
+++ python/branches/py3k/Lib/test/formatfloat_testcases.txt Wed Apr 29 20:47:07 2009
@@ -339,6 +339,8 @@
%s 1e10 -> 10000000000.0
%s 9.999e10 -> 99990000000.0
%s 99999999999 -> 99999999999.0
+%s 99999999999.9 -> 99999999999.9
+%s 99999999999.99 -> 1e+11
%s 1e11 -> 1e+11
%s 1e12 -> 1e+12
Modified: python/branches/py3k/Lib/test/test_float.py
==============================================================================
--- python/branches/py3k/Lib/test/test_float.py (original)
+++ python/branches/py3k/Lib/test/test_float.py Wed Apr 29 20:47:07 2009
@@ -328,6 +328,11 @@
self.assertEqual(fmt % float(arg), rhs)
self.assertEqual(fmt % -float(arg), '-' + rhs)
+ def test_issue5864(self):
+ self.assertEquals(format(123.456, '.4'), '123.5')
+ self.assertEquals(format(1234.56, '.4'), '1.235e+03')
+ self.assertEquals(format(12345.6, '.4'), '1.235e+04')
+
class ReprTestCase(unittest.TestCase):
def test_repr(self):
floats_file = open(os.path.join(os.path.split(__file__)[0],
Modified: python/branches/py3k/Misc/NEWS
==============================================================================
--- python/branches/py3k/Misc/NEWS (original)
+++ python/branches/py3k/Misc/NEWS Wed Apr 29 20:47:07 2009
@@ -12,6 +12,9 @@
Core and Builtins
-----------------
+- Issue #5864: Fix empty format code formatting for floats so that it
+ never gives more than the requested number of significant digits.
+
- Issue #5793: Rationalize isdigit / isalpha / tolower, etc. Includes
new Py_ISDIGIT / Py_ISALPHA / Py_TOLOWER, etc. in pctypes.h.
Modified: python/branches/py3k/Python/pystrtod.c
==============================================================================
--- python/branches/py3k/Python/pystrtod.c (original)
+++ python/branches/py3k/Python/pystrtod.c Wed Apr 29 20:47:07 2009
@@ -354,14 +354,61 @@
}
}
-/* Ensure that buffer has a decimal point in it. The decimal point will not
- be in the current locale, it will always be '.'. Don't add a decimal if an
- exponent is present. */
+/* Remove trailing zeros after the decimal point from a numeric string; also
+ remove the decimal point if all digits following it are zero. The numeric
+ string must end in '\0', and should not have any leading or trailing
+ whitespace. Assumes that the decimal point is '.'. */
Py_LOCAL_INLINE(void)
-ensure_decimal_point(char* buffer, size_t buf_size)
+remove_trailing_zeros(char *buffer)
{
- int insert_count = 0;
- char* chars_to_insert;
+ char *old_fraction_end, *new_fraction_end, *end, *p;
+
+ p = buffer;
+ if (*p == '-' || *p == '+')
+ /* Skip leading sign, if present */
+ ++p;
+ while (Py_ISDIGIT(*p))
+ ++p;
+
+ /* if there's no decimal point there's nothing to do */
+ if (*p++ != '.')
+ return;
+
+ /* scan any digits after the point */
+ while (Py_ISDIGIT(*p))
+ ++p;
+ old_fraction_end = p;
+
+ /* scan up to ending '\0' */
+ while (*p != '\0')
+ p++;
+ /* +1 to make sure that we move the null byte as well */
+ end = p+1;
+
+ /* scan back from fraction_end, looking for removable zeros */
+ p = old_fraction_end;
+ while (*(p-1) == '0')
+ --p;
+ /* and remove point if we've got that far */
+ if (*(p-1) == '.')
+ --p;
+ new_fraction_end = p;
+
+ memmove(new_fraction_end, old_fraction_end, end-old_fraction_end);
+}
+
+/* Ensure that buffer has a decimal point in it. The decimal point will not
+ be in the current locale, it will always be '.'. Don't add a decimal point
+ if an exponent is present. Also, convert to exponential notation where
+ adding a '.0' would produce too many significant digits (see issue 5864).
+
+ Returns a pointer to the fixed buffer, or NULL on failure.
+*/
+Py_LOCAL_INLINE(char *)
+ensure_decimal_point(char* buffer, size_t buf_size, int precision)
+{
+ int digit_count, insert_count = 0, convert_to_exp = 0;
+ char *chars_to_insert, *digits_start;
/* search for the first non-digit character */
char *p = buffer;
@@ -369,8 +416,10 @@
/* Skip leading sign, if present. I think this could only
ever be '-', but it can't hurt to check for both. */
++p;
+ digits_start = p;
while (*p && Py_ISDIGIT(*p))
++p;
+ digit_count = Py_SAFE_DOWNCAST(p - digits_start, Py_ssize_t, int);
if (*p == '.') {
if (Py_ISDIGIT(*(p+1))) {
@@ -380,6 +429,8 @@
else {
/* We have a decimal point, but no following
digit. Insert a zero after the decimal. */
+ /* can't ever get here via PyOS_double_to_string */
+ assert(precision == -1);
++p;
chars_to_insert = "0";
insert_count = 1;
@@ -387,8 +438,22 @@
}
else if (!(*p == 'e' || *p == 'E')) {
/* Don't add ".0" if we have an exponent. */
- chars_to_insert = ".0";
- insert_count = 2;
+ if (digit_count == precision) {
+ /* issue 5864: don't add a trailing .0 in the case
+ where the '%g'-formatted result already has as many
+ significant digits as were requested. Switch to
+ exponential notation instead. */
+ convert_to_exp = 1;
+ /* no exponent, no point, and we shouldn't land here
+ for infs and nans, so we must be at the end of the
+ string. */
+ assert(*p == '\0');
+ }
+ else {
+ assert(precision == -1 || digit_count < precision);
+ chars_to_insert = ".0";
+ insert_count = 2;
+ }
}
if (insert_count) {
size_t buf_len = strlen(buffer);
@@ -403,6 +468,30 @@
memcpy(p, chars_to_insert, insert_count);
}
}
+ if (convert_to_exp) {
+ int written;
+ size_t buf_avail;
+ p = digits_start;
+ /* insert decimal point */
+ assert(digit_count >= 1);
+ memmove(p+2, p+1, digit_count); /* safe, but overwrites nul */
+ p[1] = '.';
+ p += digit_count+1;
+ assert(p <= buf_size+buffer);
+ buf_avail = buf_size+buffer-p;
+ if (buf_avail == 0)
+ return NULL;
+ /* Add exponent. It's okay to use lower case 'e': we only
+ arrive here as a result of using the empty format code or
+ repr/str builtins and those never want an upper case 'E' */
+ written = PyOS_snprintf(p, buf_avail, "e%+.02d", digit_count-1);
+ if (!(0 <= written &&
+ written < Py_SAFE_DOWNCAST(buf_avail, size_t, int)))
+ /* output truncated, or something else bad happened */
+ return NULL;
+ remove_trailing_zeros(buffer);
+ }
+ return buffer;
}
/* see FORMATBUFLEN in unicodeobject.c */
@@ -425,12 +514,14 @@
* at least one digit after the decimal.
*
* Return value: The pointer to the buffer with the converted string.
+ * On failure returns NULL but does not set any Python exception.
**/
char *
_PyOS_ascii_formatd(char *buffer,
size_t buf_size,
const char *format,
- double d)
+ double d,
+ int precision)
{
char format_char;
size_t format_len = strlen(format);
@@ -495,9 +586,12 @@
ensure_minimum_exponent_length(buffer, buf_size);
/* If format_char is 'Z', make sure we have at least one character
- after the decimal point (and make sure we have a decimal point). */
+ after the decimal point (and make sure we have a decimal point);
+ also switch to exponential notation in some edge cases where the
+ extra character would produce more significant digits that we
+ really want. */
if (format_char == 'Z')
- ensure_decimal_point(buffer, buf_size);
+ buffer = ensure_decimal_point(buffer, buf_size, precision);
return buffer;
}
@@ -513,57 +607,13 @@
"use PyOS_double_to_string instead", 1) < 0)
return NULL;
- return _PyOS_ascii_formatd(buffer, buf_size, format, d);
+ return _PyOS_ascii_formatd(buffer, buf_size, format, d, -1);
}
#ifdef PY_NO_SHORT_FLOAT_REPR
/* The fallback code to use if _Py_dg_dtoa is not available. */
-/* Remove trailing zeros after the decimal point from a numeric string; also
- remove the decimal point if all digits following it are zero. The numeric
- string must end in '\0', and should not have any leading or trailing
- whitespace. Assumes that the decimal point is '.'. */
-Py_LOCAL_INLINE(void)
-remove_trailing_zeros(char *buffer)
-{
- char *old_fraction_end, *new_fraction_end, *end, *p;
-
- p = buffer;
- if (*p == '-' || *p == '+')
- /* Skip leading sign, if present */
- ++p;
- while (isdigit(Py_CHARMASK(*p)))
- ++p;
-
- /* if there's no decimal point there's nothing to do */
- if (*p++ != '.')
- return;
-
- /* scan any digits after the point */
- while (isdigit(Py_CHARMASK(*p)))
- ++p;
- old_fraction_end = p;
-
- /* scan up to ending '\0' */
- while (*p != '\0')
- p++;
- /* +1 to make sure that we move the null byte as well */
- end = p+1;
-
- /* scan back from fraction_end, looking for removable zeros */
- p = old_fraction_end;
- while (*(p-1) == '0')
- --p;
- /* and remove point if we've got that far */
- if (*(p-1) == '.')
- --p;
- new_fraction_end = p;
-
- memmove(new_fraction_end, old_fraction_end, end-old_fraction_end);
-}
-
-
PyAPI_FUNC(char *) PyOS_double_to_string(double val,
char format_code,
int precision,
@@ -577,7 +627,6 @@
char *p;
int t;
int upper = 0;
- int strip_trailing_zeros = 0;
/* Validate format_code, and map upper and lower case */
switch (format_code) {
@@ -612,17 +661,8 @@
PyErr_BadInternalCall();
return NULL;
}
- /* switch to exponential notation at 1e11, or 1e12 if we're
- not adding a .0 */
- if (fabs(val) >= (flags & Py_DTSF_ADD_DOT_0 ? 1e11 : 1e12)) {
- precision = 11;
- format_code = 'e';
- strip_trailing_zeros = 1;
- }
- else {
- precision = 12;
- format_code = 'g';
- }
+ precision = 12;
+ format_code = 'g';
break;
default:
PyErr_BadInternalCall();
@@ -641,18 +681,13 @@
t = Py_DTST_INFINITE;
} else {
t = Py_DTST_FINITE;
-
-
- if ((flags & Py_DTSF_ADD_DOT_0) && (format_code != 'e'))
+ if (flags & Py_DTSF_ADD_DOT_0)
format_code = 'Z';
PyOS_snprintf(format, sizeof(format), "%%%s.%i%c",
(flags & Py_DTSF_ALT ? "#" : ""), precision,
format_code);
- _PyOS_ascii_formatd(buf, sizeof(buf), format, val);
- /* remove trailing zeros if necessary */
- if (strip_trailing_zeros)
- remove_trailing_zeros(buf);
+ _PyOS_ascii_formatd(buf, sizeof(buf), format, val, precision);
}
len = strlen(buf);
@@ -678,7 +713,7 @@
/* Convert to upper case. */
char *p1;
for (p1 = p; *p1; p1++)
- *p1 = toupper(*p1);
+ *p1 = Py_TOUPPER(*p1);
}
if (type)
@@ -766,7 +801,7 @@
assert(digits_end != NULL && digits_end >= digits);
digits_len = digits_end - digits;
- if (digits_len && !isdigit(Py_CHARMASK(digits[0]))) {
+ if (digits_len && !Py_ISDIGIT(digits[0])) {
/* Infinities and nans here; adapt Gay's output,
so convert Infinity to inf and NaN to nan, and
ignore sign of nan. Then return. */
@@ -851,7 +886,8 @@
vdigits_end = decpt + precision;
break;
case 'g':
- if (decpt <= -4 || decpt > precision)
+ if (decpt <= -4 || decpt >
+ (add_dot_0_if_integer ? precision-1 : precision))
use_exp = 1;
if (use_alt_formatting)
vdigits_end = precision;
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