#include <mruby.h>

#ifndef MRB_NO_FLOAT

#include <string.h>

#include <math.h>

MRB_API mrb_bool

mrb_read_float(const char *str, char **endp, double *fp)

{

const char *p = str;

const char *a = p;

double res = 0.0, frac = 0.0, div = 1.0;

int sign = 1;

int digits = 0;

// Skip whitespace

while (ISSPACE((unsigned char)*p)) p++;

// Handle sign

if (*p == '-') { sign = -1; p++; }

else if (*p == '+') p++;

// Parse integer part

while (ISDIGIT(*p)) {

res = res * 10.0 + (*p - '0');

digits++;

a = ++p;

}

// Parse fractional part

if (*p == '.') {

p++;

while (ISDIGIT(*p)) {

frac = frac * 10.0 + (*p++ - '0');

div *= 10.0;

digits++;

}

a = p;

}

// If no digits were found, return 0

if (digits == 0) {

if (endp) *endp = (char*)str;

*fp = 0.0;

return FALSE;

}

// Combine integer and fractional parts

res += frac / div;

res *= sign;

// Handle exponent

if ((*p | 32) == 'e') {

int e = 0;

sign = 1;

p++;

if (*p == '-') { sign = -1; p++; }

else if (*p == '+') p++;

// If no digits follow 'e', ignore the exponent part

if (!ISDIGIT(*p)) goto done;

while (ISDIGIT(*p)) {

if (e < 10000) // 10000 is big enough to get Infinity

e = e * 10 + (*p - '0');

p++;

}

res *= pow(10.0, sign * e);

a = p;

}

// Set endp

done:

if (endp) *endp = (char*)a;

*fp = res;

// strtod(3) stores ERANGE to errno for overflow/underflow

// mruby does not require those checks

#if 0

// Check for underflow after applying the exponent

if (res != 0.0 && fabs(res) < DBL_MIN) {

return FALSE;

}

// Check if the result is infinity or NaN

if (isinf(res) || isnan(res)) {

return FALSE;

}

#endif

return TRUE;

}

#endif