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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).
This commit is contained in:
Eric Smith
parent
e1b8e9c666
commit
7ef40bf9c7
3 changed files with 165 additions and 34 deletions
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@ -186,6 +186,15 @@ PyOS_ascii_strtod(const char *nptr, char **endptr)
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}
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/* From the C99 standard, section 7.19.6:
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The exponent always contains at least two digits, and only as many more digits
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as necessary to represent the exponent.
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*/
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#define MIN_EXPONENT_DIGITS 2
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/* see FORMATBUFLEN in unicodeobject.c */
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#define FLOAT_FORMATBUFLEN 120
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/**
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* PyOS_ascii_formatd:
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* @buffer: A buffer to place the resulting string in
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@ -197,8 +206,10 @@ PyOS_ascii_strtod(const char *nptr, char **endptr)
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* Converts a #gdouble to a string, using the '.' as
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* decimal point. To format the number you pass in
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* a printf()-style format string. Allowed conversion
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* specifiers are 'e', 'E', 'f', 'F', 'g' and 'G'.
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* specifiers are 'e', 'E', 'f', 'F', 'g', 'G', and 'n'.
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*
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* 'n' is the same as 'g', except it uses the current locale.
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*
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* Return value: The pointer to the buffer with the converted string.
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**/
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char *
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@ -207,17 +218,23 @@ PyOS_ascii_formatd(char *buffer,
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const char *format,
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double d)
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{
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struct lconv *locale_data;
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const char *decimal_point;
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size_t decimal_point_len, rest_len;
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char *p;
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char format_char;
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size_t format_len = strlen(format);
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/* For type 'n', we need to make a copy of the format string, because
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we're going to modify 'n' -> 'g', and format is const char*, so we
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can't modify it directly. FLOAT_FORMATBUFLEN should be longer than
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we ever need this to be. There's an upcoming check to ensure it's
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big enough. */
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char tmp_format[FLOAT_FORMATBUFLEN];
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/* g_return_val_if_fail (buffer != NULL, NULL); */
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/* g_return_val_if_fail (format[0] == '%', NULL); */
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/* g_return_val_if_fail (strpbrk (format + 1, "'l%") == NULL, NULL); */
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format_char = format[strlen(format) - 1];
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/* The last character in the format string must be the format char */
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format_char = format[format_len - 1];
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/* g_return_val_if_fail (format_char == 'e' || format_char == 'E' || */
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/* format_char == 'f' || format_char == 'F' || */
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@ -227,43 +244,126 @@ PyOS_ascii_formatd(char *buffer,
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if (format[0] != '%')
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return NULL;
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/* I'm not sure why this test is here. It's ensuring that the format
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string after the first character doesn't have a single quote, a
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lowercase l, or a percent. This is the reverse of the commented-out
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test about 10 lines ago. */
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if (strpbrk(format + 1, "'l%"))
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return NULL;
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if (!(format_char == 'e' || format_char == 'E' ||
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format_char == 'f' || format_char == 'F' ||
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format_char == 'g' || format_char == 'G'))
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format_char == 'g' || format_char == 'G' ||
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format_char == 'n'))
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return NULL;
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/* Map 'n' format_char to 'g', by copying the format string and
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replacing the final 'n' with a 'g' */
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if (format_char == 'n') {
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if (format_len + 1 >= sizeof(tmp_format)) {
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/* The format won't fit in our copy. Error out. In
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practice, this will never happen and will be detected
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by returning NULL */
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return NULL;
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}
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strcpy(tmp_format, format);
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tmp_format[format_len - 1] = 'g';
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format = tmp_format;
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}
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/* Have PyOS_snprintf do the hard work */
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PyOS_snprintf(buffer, buf_len, format, d);
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locale_data = localeconv();
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decimal_point = locale_data->decimal_point;
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decimal_point_len = strlen(decimal_point);
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/* Get the current local, and find the decimal point character (or
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string?). Convert that string back to a dot. Do not do this if
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using the 'n' (number) format code. */
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if (format_char != 'n') {
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struct lconv *locale_data = localeconv();
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const char *decimal_point = locale_data->decimal_point;
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size_t decimal_point_len = strlen(decimal_point);
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size_t rest_len;
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assert(decimal_point_len != 0);
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assert(decimal_point_len != 0);
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if (decimal_point[0] != '.' ||
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decimal_point[1] != 0)
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{
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p = buffer;
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if (decimal_point[0] != '.' || decimal_point[1] != 0) {
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p = buffer;
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if (*p == '+' || *p == '-')
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p++;
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if (*p == '+' || *p == '-')
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p++;
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while (isdigit((unsigned char)*p))
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p++;
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while (isdigit(Py_CHARMASK(*p)))
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p++;
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if (strncmp(p, decimal_point, decimal_point_len) == 0)
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{
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*p = '.';
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p++;
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if (decimal_point_len > 1) {
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rest_len = strlen(p + (decimal_point_len - 1));
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memmove(p, p + (decimal_point_len - 1),
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rest_len);
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p[rest_len] = 0;
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if (strncmp(p, decimal_point, decimal_point_len) == 0) {
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*p = '.';
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p++;
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if (decimal_point_len > 1) {
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rest_len = strlen(p +
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(decimal_point_len - 1));
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memmove(p, p + (decimal_point_len - 1),
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rest_len);
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p[rest_len] = 0;
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}
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}
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}
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}
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/* If an exponent exists, ensure that the exponent is at least
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MIN_EXPONENT_DIGITS digits, providing the buffer is large enough
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for the extra zeros. Also, if there are more than
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MIN_EXPONENT_DIGITS, remove as many zeros as possible until we get
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back to MIN_EXPONENT_DIGITS */
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p = strpbrk(buffer, "eE");
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if (p && (*(p + 1) == '-' || *(p + 1) == '+')) {
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char *start = p + 2;
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int exponent_digit_cnt = 0;
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int leading_zero_cnt = 0;
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int in_leading_zeros = 1;
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int significant_digit_cnt;
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p += 2;
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while (*p && isdigit(Py_CHARMASK(*p))) {
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if (in_leading_zeros && *p == '0')
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++leading_zero_cnt;
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if (*p != '0')
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in_leading_zeros = 0;
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++p;
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++exponent_digit_cnt;
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}
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significant_digit_cnt = exponent_digit_cnt - leading_zero_cnt;
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if (exponent_digit_cnt == MIN_EXPONENT_DIGITS) {
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/* If there are 2 exactly digits, we're done,
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regardless of what they contain */
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}
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else if (exponent_digit_cnt > MIN_EXPONENT_DIGITS) {
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int extra_zeros_cnt;
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/* There are more than 2 digits in the exponent. See
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if we can delete some of the leading zeros */
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if (significant_digit_cnt < MIN_EXPONENT_DIGITS)
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significant_digit_cnt = MIN_EXPONENT_DIGITS;
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extra_zeros_cnt = exponent_digit_cnt - significant_digit_cnt;
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/* Delete extra_zeros_cnt worth of characters from the
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front of the exponent */
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assert(extra_zeros_cnt >= 0);
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/* Add one to significant_digit_cnt to copy the
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trailing 0 byte, thus setting the length */
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memmove(start,
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start + extra_zeros_cnt,
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significant_digit_cnt + 1);
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}
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else {
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/* If there are fewer than 2 digits, add zeros
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until there are 2, if there's enough room */
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int zeros = MIN_EXPONENT_DIGITS - exponent_digit_cnt;
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if (start + zeros + exponent_digit_cnt + 1
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< buffer + buf_len) {
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memmove(start + zeros, start,
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exponent_digit_cnt + 1);
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memset(start, '0', zeros);
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}
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}
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}
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