readflt.c: renamed from strtod.c

The file provides `mrb_read_float()` renamed from `vim_strtod()`.

src/readflt.c

@@ -0,0 +1,120 @@
+#include <mruby.h>
+
+#ifndef MRB_NO_FLOAT
+/*
+ * strtod implementation.
+ * author: Yasuhiro Matsumoto (@mattn)
+ * license: public domain
+ */
+
+/*
+The original code can be found in https://github.com/mattn/strtod
+
+I modified the routine for mruby:
+
+ * renamed the function `vim_strtod` -> `mrb_float_read`
+ * simplified the code
+
+My modifications in this file are also placed in the public domain.
+
+Matz (Yukihiro Matsumoto)
+*/
+
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include <errno.h>
+
+MRB_API double
+mrb_float_read(const char *str, char **end)
+{
+  double d = 0.0;
+  int sign;
+  int n = 0;
+  const char *p, *a;
+
+  a = p = str;
+  while (ISSPACE(*p))
+    ++p;
+
+  /* decimal part */
+  sign = 1;
+  if (*p == '-') {
+    sign = -1;
+    ++p;
+  } else if (*p == '+')
+    ++p;
+  if (ISDIGIT(*p)) {
+    d = (double)(*p++ - '0');
+    while (*p && ISDIGIT(*p)) {
+      d = d * 10.0 + (double)(*p - '0');
+      ++p;
+      ++n;
+    }
+    a = p;
+  } else if (*p != '.')
+    goto done;
+  d *= sign;
+
+  /* fraction part */
+  if (*p == '.') {
+    double f = 0.0;
+    double base = 0.1;
+    ++p;
+
+    if (ISDIGIT(*p))
+      {
+        while (*p && ISDIGIT(*p)) {
+          f += base * (*p - '0') ;
+          base /= 10.0;
+          ++p;
+          ++n;
+        }
+      }
+    d += f * sign;
+    a = p;
+  }
+
+  /* exponential part */
+  if ((*p == 'E') || (*p == 'e')) {
+    int e = 0;
+    ++p;
+
+    sign = 1;
+    if (*p == '-') {
+      sign = -1;
+      ++p;
+    } else if (*p == '+')
+      ++p;
+
+    if (ISDIGIT(*p)) {
+      while (*p == '0')
+        ++p;
+      if (*p == '\0') --p;
+      e = (int)(*p++ - '0');
+      for (; *p && ISDIGIT(*p); p++) {
+        if (e < 10000)
+          e = e * 10 + (*p - '0');
+      }
+      e *= sign;
+    }
+    else if (!ISDIGIT(*(a-1))) {
+      a = str;
+      goto done;
+    }
+    else if (*p == 0)
+      goto done;
+    d *= pow(10.0, (double) e);
+    a = p;
+  }
+  else if (p > str && !ISDIGIT(*(p-1))) {
+    a = str;
+    goto done;
+  }
+
+done:
+  if (end)
+    *end = (char*)a;
+  return d;
+}
+#endif