mirror of
https://github.com/python/cpython.git
synced 2025-10-25 02:43:41 +00:00
7a3b03509e
This PR removes `_Py_dg_stdnan` and `_Py_dg_infinity` in favour of using the standard `NAN` and `INFINITY` macros provided by C99. This change has the side-effect of fixing a bug on MIPS where the hard-coded value used by `_Py_dg_stdnan` gave a signalling NaN rather than a quiet NaN. --------- Co-authored-by: Mark Dickinson <dickinsm@gmail.com>
1285 lines
40 KiB
C
1285 lines
40 KiB
C
/* -*- Mode: C; c-file-style: "python" -*- */
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#include <Python.h>
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#include "pycore_dtoa.h" // _Py_dg_strtod()
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#include "pycore_pymath.h" // _PY_SHORT_FLOAT_REPR
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#include <locale.h>
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/* Case-insensitive string match used for nan and inf detection; t should be
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lower-case. Returns 1 for a successful match, 0 otherwise. */
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static int
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case_insensitive_match(const char *s, const char *t)
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{
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while(*t && Py_TOLOWER(*s) == *t) {
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s++;
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t++;
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}
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return *t ? 0 : 1;
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}
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/* _Py_parse_inf_or_nan: Attempt to parse a string of the form "nan", "inf" or
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"infinity", with an optional leading sign of "+" or "-". On success,
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return the NaN or Infinity as a double and set *endptr to point just beyond
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the successfully parsed portion of the string. On failure, return -1.0 and
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set *endptr to point to the start of the string. */
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double
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_Py_parse_inf_or_nan(const char *p, char **endptr)
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{
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double retval;
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const char *s;
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int negate = 0;
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s = p;
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if (*s == '-') {
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negate = 1;
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s++;
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}
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else if (*s == '+') {
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s++;
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}
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if (case_insensitive_match(s, "inf")) {
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s += 3;
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if (case_insensitive_match(s, "inity"))
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s += 5;
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retval = negate ? -Py_HUGE_VAL : Py_HUGE_VAL;
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}
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else if (case_insensitive_match(s, "nan")) {
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s += 3;
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retval = negate ? -fabs(Py_NAN) : fabs(Py_NAN);
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}
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else {
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s = p;
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retval = -1.0;
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}
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*endptr = (char *)s;
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return retval;
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}
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/**
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* _PyOS_ascii_strtod:
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* @nptr: the string to convert to a numeric value.
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* @endptr: if non-%NULL, it returns the character after
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* the last character used in the conversion.
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*
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* Converts a string to a #gdouble value.
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* This function behaves like the standard strtod() function
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* does in the C locale. It does this without actually
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* changing the current locale, since that would not be
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* thread-safe.
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*
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* This function is typically used when reading configuration
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* files or other non-user input that should be locale independent.
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* To handle input from the user you should normally use the
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* locale-sensitive system strtod() function.
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*
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* If the correct value would cause overflow, plus or minus %HUGE_VAL
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* is returned (according to the sign of the value), and %ERANGE is
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* stored in %errno. If the correct value would cause underflow,
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* zero is returned and %ERANGE is stored in %errno.
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* If memory allocation fails, %ENOMEM is stored in %errno.
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*
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* This function resets %errno before calling strtod() so that
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* you can reliably detect overflow and underflow.
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*
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* Return value: the #gdouble value.
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**/
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#if _PY_SHORT_FLOAT_REPR == 1
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static double
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_PyOS_ascii_strtod(const char *nptr, char **endptr)
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{
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double result;
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_Py_SET_53BIT_PRECISION_HEADER;
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assert(nptr != NULL);
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/* Set errno to zero, so that we can distinguish zero results
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and underflows */
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errno = 0;
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_Py_SET_53BIT_PRECISION_START;
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result = _Py_dg_strtod(nptr, endptr);
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_Py_SET_53BIT_PRECISION_END;
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if (*endptr == nptr)
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/* string might represent an inf or nan */
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result = _Py_parse_inf_or_nan(nptr, endptr);
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return result;
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}
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#else
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/*
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Use system strtod; since strtod is locale aware, we may
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have to first fix the decimal separator.
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Note that unlike _Py_dg_strtod, the system strtod may not always give
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correctly rounded results.
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*/
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static double
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_PyOS_ascii_strtod(const char *nptr, char **endptr)
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{
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char *fail_pos;
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double val;
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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;
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const char *p, *decimal_point_pos;
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const char *end = NULL; /* Silence gcc */
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const char *digits_pos = NULL;
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int negate = 0;
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assert(nptr != NULL);
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fail_pos = NULL;
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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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assert(decimal_point_len != 0);
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decimal_point_pos = NULL;
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/* Parse infinities and nans */
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val = _Py_parse_inf_or_nan(nptr, endptr);
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if (*endptr != nptr)
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return val;
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/* Set errno to zero, so that we can distinguish zero results
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and underflows */
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errno = 0;
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/* We process the optional sign manually, then pass the remainder to
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the system strtod. This ensures that the result of an underflow
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has the correct sign. (bug #1725) */
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p = nptr;
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/* Process leading sign, if present */
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if (*p == '-') {
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negate = 1;
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p++;
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}
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else if (*p == '+') {
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p++;
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}
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/* Some platform strtods accept hex floats; Python shouldn't (at the
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moment), so we check explicitly for strings starting with '0x'. */
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if (*p == '0' && (*(p+1) == 'x' || *(p+1) == 'X'))
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goto invalid_string;
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/* Check that what's left begins with a digit or decimal point */
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if (!Py_ISDIGIT(*p) && *p != '.')
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goto invalid_string;
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digits_pos = p;
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if (decimal_point[0] != '.' ||
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decimal_point[1] != 0)
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{
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/* Look for a '.' in the input; if present, it'll need to be
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swapped for the current locale's decimal point before we
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call strtod. On the other hand, if we find the current
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locale's decimal point then the input is invalid. */
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while (Py_ISDIGIT(*p))
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p++;
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if (*p == '.')
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{
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decimal_point_pos = p++;
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/* locate end of number */
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while (Py_ISDIGIT(*p))
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p++;
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if (*p == 'e' || *p == 'E')
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p++;
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if (*p == '+' || *p == '-')
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p++;
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while (Py_ISDIGIT(*p))
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p++;
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end = p;
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}
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else if (strncmp(p, decimal_point, decimal_point_len) == 0)
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/* Python bug #1417699 */
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goto invalid_string;
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/* For the other cases, we need not convert the decimal
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point */
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}
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if (decimal_point_pos) {
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char *copy, *c;
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/* Create a copy of the input, with the '.' converted to the
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locale-specific decimal point */
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copy = (char *)PyMem_Malloc(end - digits_pos +
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1 + decimal_point_len);
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if (copy == NULL) {
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*endptr = (char *)nptr;
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errno = ENOMEM;
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return val;
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}
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c = copy;
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memcpy(c, digits_pos, decimal_point_pos - digits_pos);
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c += decimal_point_pos - digits_pos;
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memcpy(c, decimal_point, decimal_point_len);
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c += decimal_point_len;
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memcpy(c, decimal_point_pos + 1,
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end - (decimal_point_pos + 1));
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c += end - (decimal_point_pos + 1);
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*c = 0;
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val = strtod(copy, &fail_pos);
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if (fail_pos)
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{
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if (fail_pos > decimal_point_pos)
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fail_pos = (char *)digits_pos +
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(fail_pos - copy) -
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(decimal_point_len - 1);
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else
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fail_pos = (char *)digits_pos +
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(fail_pos - copy);
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}
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PyMem_Free(copy);
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}
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else {
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val = strtod(digits_pos, &fail_pos);
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}
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if (fail_pos == digits_pos)
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goto invalid_string;
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if (negate && fail_pos != nptr)
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val = -val;
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*endptr = fail_pos;
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return val;
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invalid_string:
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*endptr = (char*)nptr;
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errno = EINVAL;
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return -1.0;
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}
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#endif
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/* PyOS_string_to_double converts a null-terminated byte string s (interpreted
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as a string of ASCII characters) to a float. The string should not have
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leading or trailing whitespace. The conversion is independent of the
|
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current locale.
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If endptr is NULL, try to convert the whole string. Raise ValueError and
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return -1.0 if the string is not a valid representation of a floating-point
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number.
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If endptr is non-NULL, try to convert as much of the string as possible.
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If no initial segment of the string is the valid representation of a
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floating-point number then *endptr is set to point to the beginning of the
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string, -1.0 is returned and again ValueError is raised.
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On overflow (e.g., when trying to convert '1e500' on an IEEE 754 machine),
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if overflow_exception is NULL then +-Py_HUGE_VAL is returned, and no Python
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exception is raised. Otherwise, overflow_exception should point to
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a Python exception, this exception will be raised, -1.0 will be returned,
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and *endptr will point just past the end of the converted value.
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If any other failure occurs (for example lack of memory), -1.0 is returned
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and the appropriate Python exception will have been set.
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*/
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double
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PyOS_string_to_double(const char *s,
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char **endptr,
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PyObject *overflow_exception)
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{
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double x, result=-1.0;
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char *fail_pos;
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errno = 0;
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x = _PyOS_ascii_strtod(s, &fail_pos);
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if (errno == ENOMEM) {
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PyErr_NoMemory();
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fail_pos = (char *)s;
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}
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else if (!endptr && (fail_pos == s || *fail_pos != '\0'))
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PyErr_Format(PyExc_ValueError,
|
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"could not convert string to float: "
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"'%.200s'", s);
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else if (fail_pos == s)
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PyErr_Format(PyExc_ValueError,
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"could not convert string to float: "
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"'%.200s'", s);
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else if (errno == ERANGE && fabs(x) >= 1.0 && overflow_exception)
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PyErr_Format(overflow_exception,
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"value too large to convert to float: "
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"'%.200s'", s);
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else
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result = x;
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if (endptr != NULL)
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*endptr = fail_pos;
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return result;
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}
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/* Remove underscores that follow the underscore placement rule from
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the string and then call the `innerfunc` function on the result.
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It should return a new object or NULL on exception.
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`what` is used for the error message emitted when underscores are detected
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that don't follow the rule. `arg` is an opaque pointer passed to the inner
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function.
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This is used to implement underscore-agnostic conversion for floats
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and complex numbers.
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*/
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PyObject *
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_Py_string_to_number_with_underscores(
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const char *s, Py_ssize_t orig_len, const char *what, PyObject *obj, void *arg,
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PyObject *(*innerfunc)(const char *, Py_ssize_t, void *))
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{
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char prev;
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const char *p, *last;
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char *dup, *end;
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PyObject *result;
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assert(s[orig_len] == '\0');
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|
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if (strchr(s, '_') == NULL) {
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return innerfunc(s, orig_len, arg);
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}
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|
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dup = PyMem_Malloc(orig_len + 1);
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if (dup == NULL) {
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return PyErr_NoMemory();
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}
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end = dup;
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prev = '\0';
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last = s + orig_len;
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for (p = s; *p; p++) {
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if (*p == '_') {
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/* Underscores are only allowed after digits. */
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if (!(prev >= '0' && prev <= '9')) {
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goto error;
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}
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}
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else {
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*end++ = *p;
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/* Underscores are only allowed before digits. */
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if (prev == '_' && !(*p >= '0' && *p <= '9')) {
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goto error;
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}
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}
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prev = *p;
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}
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/* Underscores are not allowed at the end. */
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if (prev == '_') {
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goto error;
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}
|
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/* No embedded NULs allowed. */
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if (p != last) {
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goto error;
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}
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*end = '\0';
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result = innerfunc(dup, end - dup, arg);
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|
PyMem_Free(dup);
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return result;
|
|
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|
error:
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|
PyMem_Free(dup);
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PyErr_Format(PyExc_ValueError,
|
|
"could not convert string to %s: "
|
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"%R", what, obj);
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return NULL;
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}
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|
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#if _PY_SHORT_FLOAT_REPR == 0
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|
|
|
/* Given a string that may have a decimal point in the current
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locale, change it back to a dot. Since the string cannot get
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longer, no need for a maximum buffer size parameter. */
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Py_LOCAL_INLINE(void)
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change_decimal_from_locale_to_dot(char* buffer)
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|
{
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|
struct lconv *locale_data = localeconv();
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|
const char *decimal_point = locale_data->decimal_point;
|
|
|
|
if (decimal_point[0] != '.' || decimal_point[1] != 0) {
|
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size_t decimal_point_len = strlen(decimal_point);
|
|
|
|
if (*buffer == '+' || *buffer == '-')
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buffer++;
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while (Py_ISDIGIT(*buffer))
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|
buffer++;
|
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if (strncmp(buffer, decimal_point, decimal_point_len) == 0) {
|
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*buffer = '.';
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buffer++;
|
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if (decimal_point_len > 1) {
|
|
/* buffer needs to get smaller */
|
|
size_t rest_len = strlen(buffer +
|
|
(decimal_point_len - 1));
|
|
memmove(buffer,
|
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buffer + (decimal_point_len - 1),
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rest_len);
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buffer[rest_len] = 0;
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}
|
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}
|
|
}
|
|
}
|
|
|
|
|
|
/* 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
|
|
|
|
/* Ensure that any exponent, if present, is at least MIN_EXPONENT_DIGITS
|
|
in length. */
|
|
Py_LOCAL_INLINE(void)
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|
ensure_minimum_exponent_length(char* buffer, size_t buf_size)
|
|
{
|
|
char *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;
|
|
|
|
/* Skip over the exponent and the sign. */
|
|
p += 2;
|
|
|
|
/* Find the end of the exponent, keeping track of leading
|
|
zeros. */
|
|
while (*p && Py_ISDIGIT(*p)) {
|
|
if (in_leading_zeros && *p == '0')
|
|
++leading_zero_cnt;
|
|
if (*p != '0')
|
|
in_leading_zeros = 0;
|
|
++p;
|
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++exponent_digit_cnt;
|
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}
|
|
|
|
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_size) {
|
|
memmove(start + zeros, start,
|
|
exponent_digit_cnt + 1);
|
|
memset(start, '0', zeros);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/* 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 (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;
|
|
const char *chars_to_insert;
|
|
char *digits_start;
|
|
|
|
/* search for the first non-digit character */
|
|
char *p = buffer;
|
|
if (*p == '-' || *p == '+')
|
|
/* 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))) {
|
|
/* 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 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);
|
|
if (buf_len + insert_count + 1 >= buf_size) {
|
|
/* If there is not enough room in the buffer
|
|
for the additional text, just skip it. It's
|
|
not worth generating an error over. */
|
|
}
|
|
else {
|
|
memmove(p + insert_count, p,
|
|
buffer + strlen(buffer) - p + 1);
|
|
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 */
|
|
#define FLOAT_FORMATBUFLEN 120
|
|
|
|
/**
|
|
* _PyOS_ascii_formatd:
|
|
* @buffer: A buffer to place the resulting string in
|
|
* @buf_size: The length of the buffer.
|
|
* @format: The printf()-style format to use for the
|
|
* code to use for converting.
|
|
* @d: The #gdouble to convert
|
|
* @precision: The precision to use when formatting.
|
|
*
|
|
* 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 'Z'.
|
|
*
|
|
* '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.
|
|
**/
|
|
static char *
|
|
_PyOS_ascii_formatd(char *buffer,
|
|
size_t buf_size,
|
|
const char *format,
|
|
double d,
|
|
int precision)
|
|
{
|
|
char format_char;
|
|
size_t format_len = strlen(format);
|
|
|
|
/* 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];
|
|
|
|
/* The last character in the format string must be the format char */
|
|
format_char = format[format_len - 1];
|
|
|
|
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;
|
|
|
|
/* Also curious about this function is that it accepts format strings
|
|
like "%xg", which are invalid for floats. In general, the
|
|
interface to this function is not very good, but changing it is
|
|
difficult because it's a public API. */
|
|
|
|
if (!(format_char == 'e' || format_char == 'E' ||
|
|
format_char == 'f' || format_char == 'F' ||
|
|
format_char == 'g' || format_char == 'G' ||
|
|
format_char == 'Z'))
|
|
return NULL;
|
|
|
|
/* Map 'Z' format_char to 'g', by copying the format string and
|
|
replacing the final char with a 'g' */
|
|
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
|
|
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_size, format, d);
|
|
|
|
/* Do various fixups on the return string */
|
|
|
|
/* Get the current locale, and find the decimal point string.
|
|
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
|
|
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 */
|
|
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);
|
|
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')
|
|
buffer = ensure_decimal_point(buffer, buf_size, precision);
|
|
|
|
return buffer;
|
|
}
|
|
|
|
/* The fallback code to use if _Py_dg_dtoa is not available. */
|
|
|
|
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;
|
|
}
|
|
|
|
/* 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);
|
|
|
|
if (flags & Py_DTSF_NO_NEG_0 && buf[0] == '-') {
|
|
char *buf2 = buf + 1;
|
|
while (*buf2 == '0' || *buf2 == '.') {
|
|
++buf2;
|
|
}
|
|
if (*buf2 == 0 || *buf2 == 'e') {
|
|
size_t len = buf2 - buf + strlen(buf2);
|
|
assert(buf[len] == 0);
|
|
memmove(buf, buf+1, len);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* 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;
|
|
}
|
|
|
|
#else // _PY_SHORT_FLOAT_REPR == 1
|
|
|
|
/* _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 const char * const lc_float_strings[] = {
|
|
"inf",
|
|
"nan",
|
|
"e",
|
|
};
|
|
static const char * const 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, int precision,
|
|
int always_add_sign, int add_dot_0_if_integer,
|
|
int use_alt_formatting, int no_negative_zero,
|
|
const char * const *float_strings, int *type)
|
|
{
|
|
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 (no_negative_zero && sign == 1 &&
|
|
(digits_len == 0 || (digits_len == 1 && digits[0] == '0'))) {
|
|
sign = 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. */
|
|
|
|
/* 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' */
|
|
Py_UNREACHABLE();
|
|
}
|
|
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 = (int)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;
|
|
}
|
|
|
|
|
|
char * PyOS_double_to_string(double val,
|
|
char format_code,
|
|
int precision,
|
|
int flags,
|
|
int *type)
|
|
{
|
|
const char * const *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,
|
|
flags & Py_DTSF_NO_NEG_0,
|
|
float_strings, type);
|
|
}
|
|
#endif // _PY_SHORT_FLOAT_REPR == 1
|