Issue #7117 (backport py3k float repr) continued:
Backport pystrtod.c from py3k.
diff --git a/Python/pystrtod.c b/Python/pystrtod.c
index 79f63e2..2f34b9b 100644
--- a/Python/pystrtod.c
+++ b/Python/pystrtod.c
@@ -3,6 +3,60 @@
#include <Python.h>
#include <locale.h>
+/* 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:
* @nptr: the string to convert to a numeric value.
@@ -32,6 +86,33 @@
* Return value: the #gdouble value.
**/
+#ifndef PY_NO_SHORT_FLOAT_REPR
+
+double
+_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 and 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.
@@ -40,21 +121,8 @@
correctly rounded results.
*/
-/* 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;
-}
-
double
-PyOS_ascii_strtod(const char *nptr, char **endptr)
+_PyOS_ascii_strtod(const char *nptr, char **endptr)
{
char *fail_pos;
double val = -1.0;
@@ -78,19 +146,19 @@
decimal_point_pos = NULL;
+ /* Parse infinities and nans */
+ val = _Py_parse_inf_or_nan(nptr, endptr);
+ if (*endptr != nptr)
+ return val;
+
/* Set errno to zero, so that we can distinguish zero results
and underflows */
errno = 0;
- /* 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) */
-
+ /* 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;
- /* Skip leading space */
- while (Py_ISSPACE(*p))
- p++;
-
/* Process leading sign, if present */
if (*p == '-') {
negate = 1;
@@ -100,31 +168,6 @@
p++;
}
- /* Parse infinities and nans */
- if (*p == 'i' || *p == 'I') {
- if (case_insensitive_match(p+1, "nf")) {
- val = Py_HUGE_VAL;
- if (case_insensitive_match(p+3, "inity"))
- fail_pos = (char *)p+8;
- else
- fail_pos = (char *)p+3;
- goto got_val;
- }
- else
- goto invalid_string;
- }
-#ifdef Py_NAN
- if (*p == 'n' || *p == 'N') {
- if (case_insensitive_match(p+1, "an")) {
- val = Py_NAN;
- fail_pos = (char *)p+3;
- goto got_val;
- }
- else
- goto invalid_string;
- }
-#endif
-
/* 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'))
@@ -175,8 +218,7 @@
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;
}
@@ -214,28 +256,108 @@
if (fail_pos == digits_pos)
goto invalid_string;
- got_val:
if (negate && fail_pos != nptr)
val = -val;
-
- if (endptr)
- *endptr = fail_pos;
+ *endptr = fail_pos;
return val;
invalid_string:
- if (endptr)
- *endptr = (char*)nptr;
+ *endptr = (char*)nptr;
errno = EINVAL;
return -1.0;
}
+#endif
+
+double
+PyOS_ascii_strtod(const char *nptr, char **endptr)
+{
+ char *fail_pos;
+ const char *p;
+ double x;
+
+ /* _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 = (char *)fail_pos;
+ return x;
+}
+
double
PyOS_ascii_atof(const char *nptr)
{
return PyOS_ascii_strtod(nptr, NULL);
}
+/* PyOS_string_to_double is the recommended replacement for the
+ 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
locale, change it back to a dot. Since the string cannot get
@@ -415,7 +537,7 @@
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;
+ char *chars_to_insert, *digits_start;
/* search for the first non-digit character */
char *p = buffer;
@@ -505,7 +627,7 @@
#define FLOAT_FORMATBUFLEN 120
/**
- * _PyOS_ascii_formatd:
+ * 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
@@ -523,12 +645,12 @@
* Return value: The pointer to the buffer with the converted string.
* On failure returns NULL but does not set any Python exception.
**/
-/* DEPRECATED, will be deleted in 2.8 and 3.2 */
-PyAPI_FUNC(char *)
-PyOS_ascii_formatd(char *buffer,
+char *
+_PyOS_ascii_formatd(char *buffer,
size_t buf_size,
const char *format,
- double d)
+ double d,
+ int precision)
{
char format_char;
size_t format_len = strlen(format);
@@ -537,11 +659,6 @@
also with at least one character past the decimal. */
char tmp_format[FLOAT_FORMATBUFLEN];
- if (PyErr_WarnEx(PyExc_DeprecationWarning,
- "PyOS_ascii_formatd is deprecated, "
- "use PyOS_double_to_string instead", 1) < 0)
- return NULL;
-
/* The last character in the format string must be the format char */
format_char = format[format_len - 1];
@@ -603,24 +720,24 @@
extra character would produce more significant digits that we
really want. */
if (format_char == 'Z')
- buffer = ensure_decimal_point(buffer, buf_size, -1);
+ buffer = ensure_decimal_point(buffer, buf_size, precision);
return buffer;
}
-/* Precisions used by repr() and str(), respectively.
+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;
- 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.
-
- The str() precision (12 significant decimal digits) is chosen so that in
- most cases, the rounding noise created by various operations is suppressed,
- while giving plenty of precision for practical use.
-
-*/
+ return _PyOS_ascii_formatd(buffer, buf_size, format, d, -1);
+}
PyAPI_FUNC(void)
_PyOS_double_to_string(char *buf, size_t buf_len, double val,
@@ -738,31 +855,520 @@
}
+#ifdef PY_NO_SHORT_FLOAT_REPR
+
+/* 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 *ptype)
+ int *type)
{
- char buf[128];
- Py_ssize_t len;
- char *result;
+ char format[32];
+ Py_ssize_t bufsize;
+ char *buf;
+ int t, exp;
+ int upper = 0;
- _PyOS_double_to_string(buf, sizeof(buf), val, format_code, precision,
- flags, ptype);
- len = strlen(buf);
- if (len == 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;
}
- /* Add 1 for the trailing 0 byte. */
- result = PyMem_Malloc(len + 1);
- if (result == 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;
}
- strcpy(result, buf);
- return result;
+ /* 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;
}
+
+#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)
+{
+ 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 */