diff options
Diffstat (limited to 'Python/pystrtod.c')
| -rw-r--r-- | Python/pystrtod.c | 993 |
1 files changed, 876 insertions, 117 deletions
diff --git a/Python/pystrtod.c b/Python/pystrtod.c index 9004cf4..859af43 100644 --- a/Python/pystrtod.c +++ b/Python/pystrtod.c @@ -3,11 +3,59 @@ #include <Python.h> #include <locale.h> -/* ascii character tests (as opposed to locale tests) */ -#define ISSPACE(c) ((c) == ' ' || (c) == '\f' || (c) == '\n' || \ - (c) == '\r' || (c) == '\t' || (c) == '\v') -#define ISDIGIT(c) ((c) >= '0' && (c) <= '9') +/* Case-insensitive string match used for nan and inf detection; t should be + lower-case. Returns 1 for a successful match, 0 otherwise. */ +static int +case_insensitive_match(const char *s, const char *t) +{ + while(*t && Py_TOLOWER(*s) == *t) { + s++; + t++; + } + return *t ? 0 : 1; +} + +/* _Py_parse_inf_or_nan: Attempt to parse a string of the form "nan", "inf" or + "infinity", with an optional leading sign of "+" or "-". On success, + return the NaN or Infinity as a double and set *endptr to point just beyond + the successfully parsed portion of the string. On failure, return -1.0 and + set *endptr to point to the start of the string. */ + +double +_Py_parse_inf_or_nan(const char *p, char **endptr) +{ + double retval; + const char *s; + int negate = 0; + + s = p; + if (*s == '-') { + negate = 1; + s++; + } + else if (*s == '+') { + s++; + } + if (case_insensitive_match(s, "inf")) { + s += 3; + if (case_insensitive_match(s, "inity")) + s += 5; + retval = negate ? -Py_HUGE_VAL : Py_HUGE_VAL; + } +#ifdef Py_NAN + else if (case_insensitive_match(s, "nan")) { + s += 3; + retval = negate ? -Py_NAN : Py_NAN; + } +#endif + else { + s = p; + retval = -1.0; + } + *endptr = (char *)s; + return retval; +} /** * PyOS_ascii_strtod: @@ -37,8 +85,44 @@ * * Return value: the #gdouble value. **/ + +#ifndef PY_NO_SHORT_FLOAT_REPR + double -PyOS_ascii_strtod(const char *nptr, char **endptr) +_PyOS_ascii_strtod(const char *nptr, char **endptr) +{ + double result; + _Py_SET_53BIT_PRECISION_HEADER; + + assert(nptr != NULL); + /* Set errno to zero, so that we can distinguish zero results + and underflows */ + errno = 0; + + _Py_SET_53BIT_PRECISION_START; + result = _Py_dg_strtod(nptr, endptr); + _Py_SET_53BIT_PRECISION_END; + + if (*endptr == nptr) + /* string might represent an inf or nan */ + result = _Py_parse_inf_or_nan(nptr, endptr); + + return result; + +} + +#else + +/* + Use system strtod; since strtod is locale aware, we may + have to first fix the decimal separator. + + Note that unlike _Py_dg_strtod, the system strtod may not always give + correctly rounded results. +*/ + +double +_PyOS_ascii_strtod(const char *nptr, char **endptr) { char *fail_pos; double val = -1.0; @@ -62,85 +146,79 @@ PyOS_ascii_strtod(const char *nptr, char **endptr) decimal_point_pos = NULL; - /* We process any leading whitespace and the optional sign manually, - then pass the remainder to the system strtod. This ensures that - the result of an underflow has the correct sign. (bug #1725) */ + /* Parse infinities and nans */ + val = _Py_parse_inf_or_nan(nptr, endptr); + if (*endptr != nptr) + return val; - p = nptr; - /* Skip leading space */ - while (ISSPACE(*p)) - p++; + /* Set errno to zero, so that we can distinguish zero results + and underflows */ + errno = 0; + /* We process the optional sign manually, then pass the remainder to + the system strtod. This ensures that the result of an underflow + has the correct sign. (bug #1725) */ + p = nptr; /* Process leading sign, if present */ if (*p == '-') { negate = 1; p++; - } else if (*p == '+') { + } + else if (*p == '+') { p++; } - /* What's left should begin with a digit, a decimal point, or one of - the letters i, I, n, N. It should not begin with 0x or 0X */ - if ((!ISDIGIT(*p) && - *p != '.' && *p != 'i' && *p != 'I' && *p != 'n' && *p != 'N') - || - (*p == '0' && (p[1] == 'x' || p[1] == 'X'))) - { - if (endptr) - *endptr = (char*)nptr; - errno = EINVAL; - return val; - } - digits_pos = p; + /* Some platform strtods accept hex floats; Python shouldn't (at the + moment), so we check explicitly for strings starting with '0x'. */ + if (*p == '0' && (*(p+1) == 'x' || *(p+1) == 'X')) + goto invalid_string; + + /* Check that what's left begins with a digit or decimal point */ + if (!Py_ISDIGIT(*p) && *p != '.') + goto invalid_string; + digits_pos = p; if (decimal_point[0] != '.' || decimal_point[1] != 0) { - while (ISDIGIT(*p)) + /* Look for a '.' in the input; if present, it'll need to be + swapped for the current locale's decimal point before we + call strtod. On the other hand, if we find the current + locale's decimal point then the input is invalid. */ + while (Py_ISDIGIT(*p)) p++; if (*p == '.') { decimal_point_pos = p++; - while (ISDIGIT(*p)) + /* locate end of number */ + while (Py_ISDIGIT(*p)) p++; if (*p == 'e' || *p == 'E') p++; if (*p == '+' || *p == '-') p++; - while (ISDIGIT(*p)) + while (Py_ISDIGIT(*p)) p++; end = p; } else if (strncmp(p, decimal_point, decimal_point_len) == 0) - { /* Python bug #1417699 */ - if (endptr) - *endptr = (char*)nptr; - errno = EINVAL; - return val; - } + goto invalid_string; /* For the other cases, we need not convert the decimal point */ } - /* Set errno to zero, so that we can distinguish zero results - and underflows */ - errno = 0; - - if (decimal_point_pos) - { + if (decimal_point_pos) { char *copy, *c; - - /* We need to convert the '.' to the locale specific decimal - point */ + /* Create a copy of the input, with the '.' converted to the + locale-specific decimal point */ copy = (char *)PyMem_MALLOC(end - digits_pos + 1 + decimal_point_len); if (copy == NULL) { - if (endptr) - *endptr = (char *)nptr; + *endptr = (char *)nptr; errno = ENOMEM; return val; } @@ -176,15 +254,119 @@ PyOS_ascii_strtod(const char *nptr, char **endptr) } if (fail_pos == digits_pos) - fail_pos = (char *)nptr; + goto invalid_string; if (negate && fail_pos != nptr) val = -val; + *endptr = fail_pos; + + return val; + + invalid_string: + *endptr = (char*)nptr; + errno = EINVAL; + return -1.0; +} + +#endif + +/* PyOS_ascii_strtod is DEPRECATED in Python 2.7 and 3.1 */ +double +PyOS_ascii_strtod(const char *nptr, char **endptr) +{ + char *fail_pos; + const char *p; + double x; + + if (PyErr_WarnEx(PyExc_DeprecationWarning, + "PyOS_ascii_strtod and PyOS_ascii_atof are " + "deprecated. Use PyOS_string_to_double " + "instead.", 1) < 0) + return -1.0; + + /* _PyOS_ascii_strtod already does everything that we want, + except that it doesn't parse leading whitespace */ + p = nptr; + while (Py_ISSPACE(*p)) + p++; + x = _PyOS_ascii_strtod(p, &fail_pos); + if (fail_pos == p) + fail_pos = (char *)nptr; if (endptr) - *endptr = fail_pos; + *endptr = (char *)fail_pos; + return x; +} - return val; +/* PyOS_ascii_strtod is DEPRECATED in Python 2.7 and 3.1 */ + +double +PyOS_ascii_atof(const char *nptr) +{ + return PyOS_ascii_strtod(nptr, NULL); +} + +/* PyOS_string_to_double is the recommended replacement for the deprecated + PyOS_ascii_strtod and PyOS_ascii_atof functions. It converts a + null-terminated byte string s (interpreted as a string of ASCII characters) + to a float. The string should not have leading or trailing whitespace (in + contrast, PyOS_ascii_strtod allows leading whitespace but not trailing + whitespace). The conversion is independent of the current locale. + + If endptr is NULL, try to convert the whole string. Raise ValueError and + return -1.0 if the string is not a valid representation of a floating-point + number. + + If endptr is non-NULL, try to convert as much of the string as possible. + If no initial segment of the string is the valid representation of a + floating-point number then *endptr is set to point to the beginning of the + string, -1.0 is returned and again ValueError is raised. + + On overflow (e.g., when trying to convert '1e500' on an IEEE 754 machine), + if overflow_exception is NULL then +-Py_HUGE_VAL is returned, and no Python + exception is raised. Otherwise, overflow_exception should point to a + a Python exception, this exception will be raised, -1.0 will be returned, + and *endptr will point just past the end of the converted value. + + If any other failure occurs (for example lack of memory), -1.0 is returned + and the appropriate Python exception will have been set. +*/ + +double +PyOS_string_to_double(const char *s, + char **endptr, + PyObject *overflow_exception) +{ + double x, result=-1.0; + char *fail_pos; + + errno = 0; + PyFPE_START_PROTECT("PyOS_string_to_double", return -1.0) + x = _PyOS_ascii_strtod(s, &fail_pos); + PyFPE_END_PROTECT(x) + + if (errno == ENOMEM) { + PyErr_NoMemory(); + fail_pos = (char *)s; + } + else if (!endptr && (fail_pos == s || *fail_pos != '\0')) + PyErr_Format(PyExc_ValueError, + "could not convert string to float: " + "%.200s", s); + else if (fail_pos == s) + PyErr_Format(PyExc_ValueError, + "could not convert string to float: " + "%.200s", s); + else if (errno == ERANGE && fabs(x) >= 1.0 && overflow_exception) + PyErr_Format(overflow_exception, + "value too large to convert to float: " + "%.200s", s); + else + result = x; + + if (endptr != NULL) + *endptr = fail_pos; + return result; } /* Given a string that may have a decimal point in the current @@ -201,7 +383,7 @@ change_decimal_from_locale_to_dot(char* buffer) if (*buffer == '+' || *buffer == '-') buffer++; - while (isdigit(Py_CHARMASK(*buffer))) + while (Py_ISDIGIT(*buffer)) buffer++; if (strncmp(buffer, decimal_point, decimal_point_len) == 0) { *buffer = '.'; @@ -244,7 +426,7 @@ ensure_minimum_exponent_length(char* buffer, size_t buf_size) /* Find the end of the exponent, keeping track of leading zeros. */ - while (*p && isdigit(Py_CHARMASK(*p))) { + while (*p && Py_ISDIGIT(*p)) { if (in_leading_zeros && *p == '0') ++leading_zero_cnt; if (*p != '0') @@ -292,13 +474,61 @@ ensure_minimum_exponent_length(char* buffer, size_t buf_size) } } -/* Ensure that buffer has a decimal point in it. The decimal point - will not be in the current locale, it will always be '.' */ +/* 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; @@ -306,25 +536,44 @@ ensure_decimal_point(char* buffer, size_t buf_size) /* Skip leading sign, if present. I think this could only ever be '-', but it can't hurt to check for both. */ ++p; - while (*p && isdigit(Py_CHARMASK(*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 (isdigit(Py_CHARMASK(*(p+1)))) { + if (Py_ISDIGIT(*(p+1))) { /* Nothing to do, we already have a decimal point and a digit after it */ } 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; } } - else { - chars_to_insert = ".0"; - insert_count = 2; + else if (!(*p == 'e' || *p == 'E')) { + /* Don't add ".0" if we have an exponent. */ + 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); @@ -339,37 +588,30 @@ ensure_decimal_point(char* buffer, size_t buf_size) memcpy(p, chars_to_insert, insert_count); } } -} - -/* Add the locale specific grouping characters to buffer. Note - that any decimal point (if it's present) in buffer is already - locale-specific. Return 0 on error, else 1. */ -Py_LOCAL_INLINE(int) -add_thousands_grouping(char* buffer, size_t buf_size) -{ - Py_ssize_t len = strlen(buffer); - struct lconv *locale_data = localeconv(); - const char *decimal_point = locale_data->decimal_point; - - /* Find the decimal point, if any. We're only concerned - about the characters to the left of the decimal when - adding grouping. */ - char *p = strstr(buffer, decimal_point); - if (!p) { - /* No decimal, use the entire string. */ - - /* If any exponent, adjust p. */ - p = strpbrk(buffer, "eE"); - if (!p) - /* No exponent and no decimal. Use the entire - string. */ - p = buffer + len; + 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); } - /* At this point, p points just past the right-most character we - want to format. We need to add the grouping string for the - characters between buffer and p. */ - return _PyString_InsertThousandsGrouping(buffer, len, p-buffer, - buf_size, NULL, 1); + return buffer; } /* see FORMATBUFLEN in unicodeobject.c */ @@ -386,28 +628,24 @@ add_thousands_grouping(char* buffer, size_t buf_size) * 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', 'G', and 'n'. + * specifiers are 'e', 'E', 'f', 'F', 'g', 'G', and 'Z'. * - * 'n' is the same as 'g', except it uses the current locale. * 'Z' is the same as 'g', except it always has a decimal and * 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, +_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); - /* 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. */ /* Issue 2264: code 'Z' requires copying the format. 'Z' is 'g', but also with at least one character past the decimal. */ char tmp_format[FLOAT_FORMATBUFLEN]; @@ -433,12 +671,12 @@ PyOS_ascii_formatd(char *buffer, if (!(format_char == 'e' || format_char == 'E' || format_char == 'f' || format_char == 'F' || format_char == 'g' || format_char == 'G' || - format_char == 'n' || format_char == 'Z')) + format_char == 'Z')) return NULL; - /* Map 'n' or 'Z' format_char to 'g', by copying the format string and + /* Map 'Z' format_char to 'g', by copying the format string and replacing the final char with a 'g' */ - if (format_char == 'n' || format_char == 'Z') { + if (format_char == 'Z') { 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 @@ -457,11 +695,8 @@ PyOS_ascii_formatd(char *buffer, /* Do various fixups on the return string */ /* Get the current locale, and find the decimal point string. - Convert that string back to a dot. Do not do this if using the - 'n' (number) format code, since we want to keep the localized - decimal point in that case. */ - if (format_char != 'n') - change_decimal_from_locale_to_dot(buffer); + Convert that string back to a dot. */ + change_decimal_from_locale_to_dot(buffer); /* If an exponent exists, ensure that the exponent is at least MIN_EXPONENT_DIGITS digits, providing the buffer is large enough @@ -471,20 +706,544 @@ PyOS_ascii_formatd(char *buffer, 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; +} + +char * +PyOS_ascii_formatd(char *buffer, + size_t buf_size, + const char *format, + double d) +{ + if (PyErr_WarnEx(PyExc_DeprecationWarning, + "PyOS_ascii_formatd is deprecated, " + "use PyOS_double_to_string instead", 1) < 0) + return NULL; + + return _PyOS_ascii_formatd(buffer, buf_size, format, d, -1); +} + +#ifdef PY_NO_SHORT_FLOAT_REPR - /* If format_char is 'n', add the thousands grouping. */ - if (format_char == 'n') - if (!add_thousands_grouping(buffer, buf_size)) +/* The fallback code to use if _Py_dg_dtoa is not available. */ + +PyAPI_FUNC(char *) PyOS_double_to_string(double val, + char format_code, + int precision, + int flags, + int *type) +{ + char format[32]; + Py_ssize_t bufsize; + char *buf; + int t, exp; + int upper = 0; + + /* Validate format_code, and map upper and lower case */ + switch (format_code) { + case 'e': /* exponent */ + case 'f': /* fixed */ + case 'g': /* general */ + break; + case 'E': + upper = 1; + format_code = 'e'; + break; + case 'F': + upper = 1; + format_code = 'f'; + break; + case 'G': + upper = 1; + format_code = 'g'; + break; + case 'r': /* repr format */ + /* Supplied precision is unused, must be 0. */ + if (precision != 0) { + PyErr_BadInternalCall(); return NULL; + } + /* 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. */ + precision = 17; + format_code = 'g'; + break; + default: + PyErr_BadInternalCall(); + return NULL; + } - return buffer; + /* Here's a quick-and-dirty calculation to figure out how big a buffer + we need. In general, for a finite float we need: + + 1 byte for each digit of the decimal significand, and + + 1 for a possible sign + 1 for a possible decimal point + 2 for a possible [eE][+-] + 1 for each digit of the exponent; if we allow 19 digits + total then we're safe up to exponents of 2**63. + 1 for the trailing nul byte + + This gives a total of 24 + the number of digits in the significand, + and the number of digits in the significand is: + + for 'g' format: at most precision, except possibly + when precision == 0, when it's 1. + for 'e' format: precision+1 + for 'f' format: precision digits after the point, at least 1 + before. To figure out how many digits appear before the point + we have to examine the size of the number. If fabs(val) < 1.0 + then there will be only one digit before the point. If + fabs(val) >= 1.0, then there are at most + + 1+floor(log10(ceiling(fabs(val)))) + + digits before the point (where the 'ceiling' allows for the + possibility that the rounding rounds the integer part of val + up). A safe upper bound for the above quantity is + 1+floor(exp/3), where exp is the unique integer such that 0.5 + <= fabs(val)/2**exp < 1.0. This exp can be obtained from + frexp. + + So we allow room for precision+1 digits for all formats, plus an + extra floor(exp/3) digits for 'f' format. + + */ + + if (Py_IS_NAN(val) || Py_IS_INFINITY(val)) + /* 3 for 'inf'/'nan', 1 for sign, 1 for '\0' */ + bufsize = 5; + else { + bufsize = 25 + precision; + if (format_code == 'f' && fabs(val) >= 1.0) { + frexp(val, &exp); + bufsize += exp/3; + } + } + + buf = PyMem_Malloc(bufsize); + if (buf == NULL) { + PyErr_NoMemory(); + return NULL; + } + + /* Handle nan and inf. */ + if (Py_IS_NAN(val)) { + strcpy(buf, "nan"); + t = Py_DTST_NAN; + } else if (Py_IS_INFINITY(val)) { + if (copysign(1., val) == 1.) + strcpy(buf, "inf"); + else + strcpy(buf, "-inf"); + t = Py_DTST_INFINITE; + } else { + t = Py_DTST_FINITE; + 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, bufsize, format, val, precision); + } + + /* Add sign when requested. It's convenient (esp. when formatting + complex numbers) to include a sign even for inf and nan. */ + if (flags & Py_DTSF_SIGN && buf[0] != '-') { + size_t len = strlen(buf); + /* the bufsize calculations above should ensure that we've got + space to add a sign */ + assert((size_t)bufsize >= len+2); + memmove(buf+1, buf, len+1); + buf[0] = '+'; + } + if (upper) { + /* Convert to upper case. */ + char *p1; + for (p1 = buf; *p1; p1++) + *p1 = Py_TOUPPER(*p1); + } + + if (type) + *type = t; + return buf; } -double -PyOS_ascii_atof(const char *nptr) +#else + +/* _Py_dg_dtoa is available. */ + +/* I'm using a lookup table here so that I don't have to invent a non-locale + specific way to convert to uppercase */ +#define OFS_INF 0 +#define OFS_NAN 1 +#define OFS_E 2 + +/* The lengths of these are known to the code below, so don't change them */ +static char *lc_float_strings[] = { + "inf", + "nan", + "e", +}; +static char *uc_float_strings[] = { + "INF", + "NAN", + "E", +}; + + +/* Convert a double d to a string, and return a PyMem_Malloc'd block of + memory contain the resulting string. + + Arguments: + d is the double to be converted + format_code is one of 'e', 'f', 'g', 'r'. 'e', 'f' and 'g' + correspond to '%e', '%f' and '%g'; 'r' corresponds to repr. + mode is one of '0', '2' or '3', and is completely determined by + format_code: 'e' and 'g' use mode 2; 'f' mode 3, 'r' mode 0. + precision is the desired precision + always_add_sign is nonzero if a '+' sign should be included for positive + numbers + add_dot_0_if_integer is nonzero if integers in non-exponential form + should have ".0" added. Only applies to format codes 'r' and 'g'. + use_alt_formatting is nonzero if alternative formatting should be + used. Only applies to format codes 'e', 'f' and 'g'. For code 'g', + at most one of use_alt_formatting and add_dot_0_if_integer should + be nonzero. + type, if non-NULL, will be set to one of these constants to identify + the type of the 'd' argument: + Py_DTST_FINITE + Py_DTST_INFINITE + Py_DTST_NAN + + Returns a PyMem_Malloc'd block of memory containing the resulting string, + or NULL on error. If NULL is returned, the Python error has been set. + */ + +static char * +format_float_short(double d, char format_code, + int mode, Py_ssize_t precision, + int always_add_sign, int add_dot_0_if_integer, + int use_alt_formatting, char **float_strings, int *type) { - return PyOS_ascii_strtod(nptr, NULL); + char *buf = NULL; + char *p = NULL; + Py_ssize_t bufsize = 0; + char *digits, *digits_end; + int decpt_as_int, sign, exp_len, exp = 0, use_exp = 0; + Py_ssize_t decpt, digits_len, vdigits_start, vdigits_end; + _Py_SET_53BIT_PRECISION_HEADER; + + /* _Py_dg_dtoa returns a digit string (no decimal point or exponent). + Must be matched by a call to _Py_dg_freedtoa. */ + _Py_SET_53BIT_PRECISION_START; + digits = _Py_dg_dtoa(d, mode, precision, &decpt_as_int, &sign, + &digits_end); + _Py_SET_53BIT_PRECISION_END; + + decpt = (Py_ssize_t)decpt_as_int; + if (digits == NULL) { + /* The only failure mode is no memory. */ + PyErr_NoMemory(); + goto exit; + } + assert(digits_end != NULL && digits_end >= digits); + digits_len = digits_end - digits; + + 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. */ + + /* ignore the actual sign of a nan */ + if (digits[0] == 'n' || digits[0] == 'N') + sign = 0; + + /* We only need 5 bytes to hold the result "+inf\0" . */ + bufsize = 5; /* Used later in an assert. */ + buf = (char *)PyMem_Malloc(bufsize); + if (buf == NULL) { + PyErr_NoMemory(); + goto exit; + } + p = buf; + + if (sign == 1) { + *p++ = '-'; + } + else if (always_add_sign) { + *p++ = '+'; + } + if (digits[0] == 'i' || digits[0] == 'I') { + strncpy(p, float_strings[OFS_INF], 3); + p += 3; + + if (type) + *type = Py_DTST_INFINITE; + } + else if (digits[0] == 'n' || digits[0] == 'N') { + strncpy(p, float_strings[OFS_NAN], 3); + p += 3; + + if (type) + *type = Py_DTST_NAN; + } + else { + /* shouldn't get here: Gay's code should always return + something starting with a digit, an 'I', or 'N' */ + strncpy(p, "ERR", 3); + p += 3; + assert(0); + } + goto exit; + } + + /* The result must be finite (not inf or nan). */ + if (type) + *type = Py_DTST_FINITE; + + + /* We got digits back, format them. We may need to pad 'digits' + either on the left or right (or both) with extra zeros, so in + general the resulting string has the form + + [<sign>]<zeros><digits><zeros>[<exponent>] + + where either of the <zeros> pieces could be empty, and there's a + decimal point that could appear either in <digits> or in the + leading or trailing <zeros>. + + Imagine an infinite 'virtual' string vdigits, consisting of the + string 'digits' (starting at index 0) padded on both the left and + right with infinite strings of zeros. We want to output a slice + + vdigits[vdigits_start : vdigits_end] + + of this virtual string. Thus if vdigits_start < 0 then we'll end + up producing some leading zeros; if vdigits_end > digits_len there + will be trailing zeros in the output. The next section of code + determines whether to use an exponent or not, figures out the + position 'decpt' of the decimal point, and computes 'vdigits_start' + and 'vdigits_end'. */ + vdigits_end = digits_len; + switch (format_code) { + case 'e': + use_exp = 1; + vdigits_end = precision; + break; + case 'f': + vdigits_end = decpt + precision; + break; + case 'g': + if (decpt <= -4 || decpt > + (add_dot_0_if_integer ? precision-1 : precision)) + use_exp = 1; + if (use_alt_formatting) + vdigits_end = precision; + break; + case 'r': + /* convert to exponential format at 1e16. We used to convert + at 1e17, but that gives odd-looking results for some values + when a 16-digit 'shortest' repr is padded with bogus zeros. + For example, repr(2e16+8) would give 20000000000000010.0; + the true value is 20000000000000008.0. */ + if (decpt <= -4 || decpt > 16) + use_exp = 1; + break; + default: + PyErr_BadInternalCall(); + goto exit; + } + + /* if using an exponent, reset decimal point position to 1 and adjust + exponent accordingly.*/ + if (use_exp) { + exp = decpt - 1; + decpt = 1; + } + /* ensure vdigits_start < decpt <= vdigits_end, or vdigits_start < + decpt < vdigits_end if add_dot_0_if_integer and no exponent */ + vdigits_start = decpt <= 0 ? decpt-1 : 0; + if (!use_exp && add_dot_0_if_integer) + vdigits_end = vdigits_end > decpt ? vdigits_end : decpt + 1; + else + vdigits_end = vdigits_end > decpt ? vdigits_end : decpt; + + /* double check inequalities */ + assert(vdigits_start <= 0 && + 0 <= digits_len && + digits_len <= vdigits_end); + /* decimal point should be in (vdigits_start, vdigits_end] */ + assert(vdigits_start < decpt && decpt <= vdigits_end); + + /* Compute an upper bound how much memory we need. This might be a few + chars too long, but no big deal. */ + bufsize = + /* sign, decimal point and trailing 0 byte */ + 3 + + + /* total digit count (including zero padding on both sides) */ + (vdigits_end - vdigits_start) + + + /* exponent "e+100", max 3 numerical digits */ + (use_exp ? 5 : 0); + + /* Now allocate the memory and initialize p to point to the start of + it. */ + buf = (char *)PyMem_Malloc(bufsize); + if (buf == NULL) { + PyErr_NoMemory(); + goto exit; + } + p = buf; + + /* Add a negative sign if negative, and a plus sign if non-negative + and always_add_sign is true. */ + if (sign == 1) + *p++ = '-'; + else if (always_add_sign) + *p++ = '+'; + + /* note that exactly one of the three 'if' conditions is true, + so we include exactly one decimal point */ + /* Zero padding on left of digit string */ + if (decpt <= 0) { + memset(p, '0', decpt-vdigits_start); + p += decpt - vdigits_start; + *p++ = '.'; + memset(p, '0', 0-decpt); + p += 0-decpt; + } + else { + memset(p, '0', 0-vdigits_start); + p += 0 - vdigits_start; + } + + /* Digits, with included decimal point */ + if (0 < decpt && decpt <= digits_len) { + strncpy(p, digits, decpt-0); + p += decpt-0; + *p++ = '.'; + strncpy(p, digits+decpt, digits_len-decpt); + p += digits_len-decpt; + } + else { + strncpy(p, digits, digits_len); + p += digits_len; + } + + /* And zeros on the right */ + if (digits_len < decpt) { + memset(p, '0', decpt-digits_len); + p += decpt-digits_len; + *p++ = '.'; + memset(p, '0', vdigits_end-decpt); + p += vdigits_end-decpt; + } + else { + memset(p, '0', vdigits_end-digits_len); + p += vdigits_end-digits_len; + } + + /* Delete a trailing decimal pt unless using alternative formatting. */ + if (p[-1] == '.' && !use_alt_formatting) + p--; + + /* Now that we've done zero padding, add an exponent if needed. */ + if (use_exp) { + *p++ = float_strings[OFS_E][0]; + exp_len = sprintf(p, "%+.02d", exp); + p += exp_len; + } + exit: + if (buf) { + *p = '\0'; + /* It's too late if this fails, as we've already stepped on + memory that isn't ours. But it's an okay debugging test. */ + assert(p-buf < bufsize); + } + if (digits) + _Py_dg_freedtoa(digits); + + return buf; +} + + +PyAPI_FUNC(char *) PyOS_double_to_string(double val, + char format_code, + int precision, + int flags, + int *type) +{ + char **float_strings = lc_float_strings; + int mode; + + /* Validate format_code, and map upper and lower case. Compute the + mode and make any adjustments as needed. */ + switch (format_code) { + /* exponent */ + case 'E': + float_strings = uc_float_strings; + format_code = 'e'; + /* Fall through. */ + case 'e': + mode = 2; + precision++; + break; + + /* fixed */ + case 'F': + float_strings = uc_float_strings; + format_code = 'f'; + /* Fall through. */ + case 'f': + mode = 3; + break; + + /* general */ + case 'G': + float_strings = uc_float_strings; + format_code = 'g'; + /* Fall through. */ + case 'g': + mode = 2; + /* precision 0 makes no sense for 'g' format; interpret as 1 */ + if (precision == 0) + precision = 1; + break; + + /* repr format */ + case 'r': + mode = 0; + /* Supplied precision is unused, must be 0. */ + if (precision != 0) { + PyErr_BadInternalCall(); + return NULL; + } + break; + + default: + PyErr_BadInternalCall(); + return NULL; + } + + return format_float_short(val, format_code, mode, precision, + flags & Py_DTSF_SIGN, + flags & Py_DTSF_ADD_DOT_0, + flags & Py_DTSF_ALT, + float_strings, type); } +#endif /* ifdef PY_NO_SHORT_FLOAT_REPR */ |