src/readfloat.c

   1 #include <mruby.h>
   2
   3 #ifndef MRB_NO_FLOAT
   4 /*
   5  * strtod implementation.
   6  * author: Yasuhiro Matsumoto (@mattn)
   7  * license: public domain
   8  */
   9
  10 /*
  11 The original code can be found in https://github.com/mattn/strtod
  12
  13 I modified the routine for mruby:
  14
  15  * renamed the function `vim_strtod` -> `mrb_read_float`
  16  * simplified the code
  17  * changed the API
  18
  19 My modifications in this file are also placed in the public domain.
  20
  21 Matz (Yukihiro Matsumoto)
  22 */
  23
  24 #include <string.h>
  25 #include <math.h>
  26
  27 MRB_API mrb_bool
  28 mrb_read_float(const char *str, char **endp, double *fp)
  29 {
  30   double d = 0.0;
  31   int sign;
  32   int n = 0;
  33   const char *p, *a;
  34
  35   a = p = str;
  36   while (ISSPACE(*p))
  37     p++;
  38
  39   /* decimal part */
  40   sign = 1;
  41   if (*p == '-') {
  42     sign = -1;
  43     p++;
  44   }
  45   else if (*p == '+')
  46     p++;
  47   if (ISDIGIT(*p)) {
  48     d = (double)(*p++ - '0');
  49     while (*p && ISDIGIT(*p)) {
  50       d = d * 10.0 + (double)(*p - '0');
  51       p++;
  52       n++;
  53     }
  54     a = p;
  55   }
  56   else if (*p != '.')
  57     goto done;
  58   d *= sign;
  59
  60   /* fraction part */
  61   if (*p == '.') {
  62     double f = 0.0;
  63     double base = 0.1;
  64     p++;
  65
  66     if (ISDIGIT(*p)) {
  67       while (*p && ISDIGIT(*p)) {
  68         f += base * (*p - '0');
  69         base /= 10.0;
  70         p++;
  71         n++;
  72       }
  73     }
  74     d += f * sign;
  75     a = p;
  76   }
  77
  78   /* exponential part */
  79   if ((*p == 'E') || (*p == 'e')) {
  80     int e = 0;
  81
  82     p++;
  83     sign = 1;
  84     if (*p == '-') {
  85       sign = -1;
  86       p++;
  87     }
  88     else if (*p == '+')
  89       p++;
  90
  91     if (ISDIGIT(*p)) {
  92       while (*p == '0')
  93         p++;
  94       if (*p == '\0') --p;
  95       e = (int)(*p++ - '0');
  96       for (; *p && ISDIGIT(*p); p++) {
  97         if (e < 10000)
  98           e = e * 10 + (*p - '0');
  99       }
 100       e *= sign;
 101     }
 102     else if (!ISDIGIT(*(a-1))) {
 103       return FALSE;
 104     }
 105     else if (*p == 0)
 106       goto done;
 107     d *= pow(10.0, (double)e);
 108     a = p;
 109   }
 110   else if (p > str && !ISDIGIT(*(p-1))) {
 111     goto done;
 112   }
 113
 114 done:
 115   *fp = d;
 116   if (endp) *endp = (char*)a;
 117   if (str == a) return FALSE;
 118   return TRUE;
 119 }
 120 #endif