refactor valid instance variable name check

1 files changed, 29 insertions, 0 deletions

diff --git a/src/variable.c b/src/variable.c
index 6318d97fc..948bd1871 100644
--- a/src/variable.c
+++ b/src/variable.c
@@ -542,6 +542,35 @@ mrb_iv_defined(mrb_state *mrb, mrb_value obj, mrb_sym sym)
   return mrb_obj_iv_defined(mrb, mrb_obj_ptr(obj), sym);
 }
 
+MRB_API mrb_bool
+mrb_iv_p(mrb_state *mrb, mrb_sym iv_name)
+{
+  const char *s;
+  mrb_int i, len;
+  size_t j;
+  const char *invalid = "@$!? ";
+
+  s = mrb_sym2name_len(mrb, iv_name, &len);
+  if (len < 2) return FALSE;
+  if (s[0] != '@') return FALSE;
+  if (s[1] == '@') return FALSE;
+  for (i=1; i<len; i++) {
+    char c = s[i];
+    for (j=0; j<sizeof(invalid); j++) {
+      if (c == invalid[j]) return FALSE;
+    }
+  }
+  return TRUE;
+}
+
+MRB_API void
+mrb_iv_check(mrb_state *mrb, mrb_sym iv_name)
+{
+  if (!mrb_iv_p(mrb, iv_name)) {
+    mrb_name_error(mrb, iv_name, "`%S' is not allowed as an instance variable name", mrb_sym2str(mrb, iv_name));
+  }
+}
+
 MRB_API void
 mrb_iv_copy(mrb_state *mrb, mrb_value dest, mrb_value src)
 {