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   const char *p, *a;
  33
  34   a = p = str;
  35   while (ISSPACE(*p))
  36     p++;
  37
  38   /* decimal part */
  39   sign = 1;
  40   if (*p == '-') {
  41     sign = -1;
  42     p++;
  43   }
  44   else if (*p == '+')
  45     p++;
  46   if (ISDIGIT(*p)) {
  47     d = (double)(*p++ - '0');
  48     while (*p && ISDIGIT(*p)) {
  49       d = d * 10.0 + (double)(*p - '0');
  50       p++;
  51     }
  52     a = p;
  53   }
  54   else if (*p != '.')
  55     goto done;
  56   d *= sign;
  57
  58   /* fraction part */
  59   if (*p == '.') {
  60     double f = 0.0;
  61     double base = 0.1;
  62     p++;
  63
  64     if (ISDIGIT(*p)) {
  65       while (*p && ISDIGIT(*p)) {
  66         f += base * (*p - '0');
  67         base /= 10.0;
  68         p++;
  69       }
  70     }
  71     d += f * sign;
  72     a = p;
  73   }
  74
  75   /* exponential part */
  76   if ((*p == 'E') || (*p == 'e')) {
  77     int e = 0;
  78
  79     p++;
  80     sign = 1;
  81     if (*p == '-') {
  82       sign = -1;
  83       p++;
  84     }
  85     else if (*p == '+')
  86       p++;
  87
  88     if (ISDIGIT(*p)) {
  89       while (*p == '0')
  90         p++;
  91       if (*p == '\0') --p;
  92       e = (int)(*p++ - '0');
  93       for (; *p && ISDIGIT(*p); p++) {
  94         if (e < 10000)
  95           e = e * 10 + (*p - '0');
  96       }
  97       e *= sign;
  98     }
  99     else if (!ISDIGIT(*(a-1))) {
 100       return FALSE;
 101     }
 102     else if (*p == 0)
 103       goto done;
 104     d *= pow(10.0, (double)e);
 105     a = p;
 106   }
 107   else if (p > str && !ISDIGIT(*(p-1))) {
 108     goto done;
 109   }
 110
 111 done:
 112   *fp = d;
 113   if (endp) *endp = (char*)a;
 114   if (str == a) return FALSE;
 115   return TRUE;
 116 }
 117 #endif