Trim leading zeros from a floating point exponent, per C99. See issue 1600. As far as I know, this only affects Windows. Add float type 'n' to PyOS_ascii_formatd (see PEP 3101 for 'n' description).
diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
index fe2950a..bf218db 100644
--- a/Lib/test/test_types.py
+++ b/Lib/test/test_types.py
@@ -89,6 +89,29 @@
if float(1) == 1.0 and float(-1) == -1.0 and float(0) == 0.0: pass
else: self.fail('float() does not work properly')
+ def test_float_to_string(self):
+ def test(f, result):
+ self.assertEqual(f.__format__('e'), result)
+ self.assertEqual('%e' % f, result)
+
+ # test all 2 digit exponents, both with __format__ and with
+ # '%' formatting
+ for i in range(-99, 100):
+ test(float('1.5e'+str(i)), '1.500000e{0:+03d}'.format(i))
+
+ # test some 3 digit exponents
+ self.assertEqual(1.5e100.__format__('e'), '1.500000e+100')
+ self.assertEqual('%e' % 1.5e100, '1.500000e+100')
+
+ self.assertEqual(1.5e101.__format__('e'), '1.500000e+101')
+ self.assertEqual('%e' % 1.5e101, '1.500000e+101')
+
+ self.assertEqual(1.5e-100.__format__('e'), '1.500000e-100')
+ self.assertEqual('%e' % 1.5e-100, '1.500000e-100')
+
+ self.assertEqual(1.5e-101.__format__('e'), '1.500000e-101')
+ self.assertEqual('%e' % 1.5e-101, '1.500000e-101')
+
def test_normal_integers(self):
# Ensure the first 256 integers are shared
a = 256
@@ -486,16 +509,17 @@
test(-1.0, ' f', '-1.000000')
test( 1.0, '+f', '+1.000000')
test(-1.0, '+f', '-1.000000')
+ test(1.1234e90, 'f', '1.1234e+90')
+ test(1.1234e90, 'F', '1.1234e+90')
test(1.1234e200, 'f', '1.1234e+200')
test(1.1234e200, 'F', '1.1234e+200')
- # temporarily removed. see issue 1600
- # test( 1.0, 'e', '1.000000e+00')
- # test(-1.0, 'e', '-1.000000e+00')
- # test( 1.0, 'E', '1.000000E+00')
- # test(-1.0, 'E', '-1.000000E+00')
- # test(1.1234e20, 'e', '1.123400e+20')
- # test(1.1234e20, 'E', '1.123400E+20')
+ test( 1.0, 'e', '1.000000e+00')
+ test(-1.0, 'e', '-1.000000e+00')
+ test( 1.0, 'E', '1.000000E+00')
+ test(-1.0, 'E', '-1.000000E+00')
+ test(1.1234e20, 'e', '1.123400e+20')
+ test(1.1234e20, 'E', '1.123400E+20')
# % formatting
test(-1.0, '%', '-100.000000%')
diff --git a/Misc/NEWS b/Misc/NEWS
index 40b78fc..f4d1cc5 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,13 @@
Core and builtins
-----------------
+- Issue #1600: Modifed PyOS_ascii_formatd to use at most 2 digit
+ exponents for exponents with absolute value < 100. Follows C99
+ standard. This is a change on Windows, which would use 3 digits.
+ Also, added 'n' to the formats that PyOS_ascii_formatd understands,
+ so that any alterations it does to the resulting string will be
+ available in stringlib/formatter.h (for float.__format__).
+
- Implemented PEP 3101, Advanced String Formatting. This adds a new
builtin format(); a format() method for str and unicode; a
__format__() method to object, str, unicode, int, long, float, and
diff --git a/Python/pystrtod.c b/Python/pystrtod.c
index 14fb84b..16efa9d 100644
--- a/Python/pystrtod.c
+++ b/Python/pystrtod.c
@@ -186,6 +186,15 @@
}
+/* From the C99 standard, section 7.19.6:
+The exponent always contains at least two digits, and only as many more digits
+as necessary to represent the exponent.
+*/
+#define MIN_EXPONENT_DIGITS 2
+
+/* see FORMATBUFLEN in unicodeobject.c */
+#define FLOAT_FORMATBUFLEN 120
+
/**
* PyOS_ascii_formatd:
* @buffer: A buffer to place the resulting string in
@@ -197,8 +206,10 @@
* Converts a #gdouble to a string, using the '.' as
* decimal point. To format the number you pass in
* a printf()-style format string. Allowed conversion
- * specifiers are 'e', 'E', 'f', 'F', 'g' and 'G'.
+ * specifiers are 'e', 'E', 'f', 'F', 'g', 'G', and 'n'.
*
+ * 'n' is the same as 'g', except it uses the current locale.
+ *
* Return value: The pointer to the buffer with the converted string.
**/
char *
@@ -207,17 +218,23 @@
const char *format,
double d)
{
- struct lconv *locale_data;
- const char *decimal_point;
- size_t decimal_point_len, rest_len;
char *p;
char format_char;
+ size_t format_len = strlen(format);
+
+ /* For type 'n', we need to make a copy of the format string, because
+ we're going to modify 'n' -> 'g', and format is const char*, so we
+ can't modify it directly. FLOAT_FORMATBUFLEN should be longer than
+ we ever need this to be. There's an upcoming check to ensure it's
+ big enough. */
+ char tmp_format[FLOAT_FORMATBUFLEN];
/* g_return_val_if_fail (buffer != NULL, NULL); */
/* g_return_val_if_fail (format[0] == '%', NULL); */
/* g_return_val_if_fail (strpbrk (format + 1, "'l%") == NULL, NULL); */
- format_char = format[strlen(format) - 1];
+ /* The last character in the format string must be the format char */
+ format_char = format[format_len - 1];
/* g_return_val_if_fail (format_char == 'e' || format_char == 'E' || */
/* format_char == 'f' || format_char == 'F' || */
@@ -227,43 +244,126 @@
if (format[0] != '%')
return NULL;
+ /* I'm not sure why this test is here. It's ensuring that the format
+ string after the first character doesn't have a single quote, a
+ lowercase l, or a percent. This is the reverse of the commented-out
+ test about 10 lines ago. */
if (strpbrk(format + 1, "'l%"))
return NULL;
if (!(format_char == 'e' || format_char == 'E' ||
format_char == 'f' || format_char == 'F' ||
- format_char == 'g' || format_char == 'G'))
+ format_char == 'g' || format_char == 'G' ||
+ format_char == 'n'))
return NULL;
+ /* Map 'n' format_char to 'g', by copying the format string and
+ replacing the final 'n' with a 'g' */
+ if (format_char == 'n') {
+ if (format_len + 1 >= sizeof(tmp_format)) {
+ /* The format won't fit in our copy. Error out. In
+ practice, this will never happen and will be detected
+ by returning NULL */
+ return NULL;
+ }
+ strcpy(tmp_format, format);
+ tmp_format[format_len - 1] = 'g';
+ format = tmp_format;
+ }
+ /* Have PyOS_snprintf do the hard work */
PyOS_snprintf(buffer, buf_len, format, d);
- locale_data = localeconv();
- decimal_point = locale_data->decimal_point;
- decimal_point_len = strlen(decimal_point);
+ /* Get the current local, and find the decimal point character (or
+ string?). Convert that string back to a dot. Do not do this if
+ using the 'n' (number) format code. */
+ if (format_char != 'n') {
+ struct lconv *locale_data = localeconv();
+ const char *decimal_point = locale_data->decimal_point;
+ size_t decimal_point_len = strlen(decimal_point);
+ size_t rest_len;
- assert(decimal_point_len != 0);
+ assert(decimal_point_len != 0);
- if (decimal_point[0] != '.' ||
- decimal_point[1] != 0)
- {
- p = buffer;
+ if (decimal_point[0] != '.' || decimal_point[1] != 0) {
+ p = buffer;
- if (*p == '+' || *p == '-')
- p++;
+ if (*p == '+' || *p == '-')
+ p++;
- while (isdigit((unsigned char)*p))
- p++;
+ while (isdigit(Py_CHARMASK(*p)))
+ p++;
- if (strncmp(p, decimal_point, decimal_point_len) == 0)
- {
- *p = '.';
- p++;
- if (decimal_point_len > 1) {
- rest_len = strlen(p + (decimal_point_len - 1));
- memmove(p, p + (decimal_point_len - 1),
- rest_len);
- p[rest_len] = 0;
+ if (strncmp(p, decimal_point, decimal_point_len) == 0) {
+ *p = '.';
+ p++;
+ if (decimal_point_len > 1) {
+ rest_len = strlen(p +
+ (decimal_point_len - 1));
+ memmove(p, p + (decimal_point_len - 1),
+ rest_len);
+ p[rest_len] = 0;
+ }
+ }
+ }
+ }
+
+ /* If an exponent exists, ensure that the exponent is at least
+ MIN_EXPONENT_DIGITS digits, providing the buffer is large enough
+ for the extra zeros. Also, if there are more than
+ MIN_EXPONENT_DIGITS, remove as many zeros as possible until we get
+ back to MIN_EXPONENT_DIGITS */
+ p = strpbrk(buffer, "eE");
+ if (p && (*(p + 1) == '-' || *(p + 1) == '+')) {
+ char *start = p + 2;
+ int exponent_digit_cnt = 0;
+ int leading_zero_cnt = 0;
+ int in_leading_zeros = 1;
+ int significant_digit_cnt;
+
+ p += 2;
+ while (*p && isdigit(Py_CHARMASK(*p))) {
+ if (in_leading_zeros && *p == '0')
+ ++leading_zero_cnt;
+ if (*p != '0')
+ in_leading_zeros = 0;
+ ++p;
+ ++exponent_digit_cnt;
+ }
+
+ significant_digit_cnt = exponent_digit_cnt - leading_zero_cnt;
+ if (exponent_digit_cnt == MIN_EXPONENT_DIGITS) {
+ /* If there are 2 exactly digits, we're done,
+ regardless of what they contain */
+ }
+ else if (exponent_digit_cnt > MIN_EXPONENT_DIGITS) {
+ int extra_zeros_cnt;
+
+ /* There are more than 2 digits in the exponent. See
+ if we can delete some of the leading zeros */
+ if (significant_digit_cnt < MIN_EXPONENT_DIGITS)
+ significant_digit_cnt = MIN_EXPONENT_DIGITS;
+ extra_zeros_cnt = exponent_digit_cnt - significant_digit_cnt;
+
+ /* Delete extra_zeros_cnt worth of characters from the
+ front of the exponent */
+ assert(extra_zeros_cnt >= 0);
+
+ /* Add one to significant_digit_cnt to copy the
+ trailing 0 byte, thus setting the length */
+ memmove(start,
+ start + extra_zeros_cnt,
+ significant_digit_cnt + 1);
+ }
+ else {
+ /* If there are fewer than 2 digits, add zeros
+ until there are 2, if there's enough room */
+ int zeros = MIN_EXPONENT_DIGITS - exponent_digit_cnt;
+ if (start + zeros + exponent_digit_cnt + 1
+ < buffer + buf_len) {
+ memmove(start + zeros, start,
+ exponent_digit_cnt + 1);
+ memset(start, '0', zeros);
}
}
}