add new functions to check if symbols are interned without registration.

include/mruby.h

@@ -195,6 +195,9 @@ mrb_value mrb_funcall_with_block(mrb_state*, mrb_value, mrb_sym, int, mrb_value*
 mrb_sym mrb_intern_cstr(mrb_state*,const char*);
 mrb_sym mrb_intern2(mrb_state*,const char*,size_t);
 mrb_sym mrb_intern_str(mrb_state*,mrb_value);
+mrb_bool mrb_cstr_interned(mrb_state*,const char*);
+mrb_bool mrb_interned(mrb_state*,const char*,size_t);
+mrb_bool mrb_str_interned(mrb_state*,mrb_value);
 const char *mrb_sym2name(mrb_state*,mrb_sym);
 const char *mrb_sym2name_len(mrb_state*,mrb_sym,size_t*);
 mrb_value mrb_sym2str(mrb_state*,mrb_sym);

src/symbol.c

@@ -72,6 +72,30 @@ mrb_intern_str(mrb_state *mrb, mrb_value str)
   return mrb_intern2(mrb, RSTRING_PTR(str), RSTRING_LEN(str));
 }
 
+mrb_bool
+mrb_cstr_interned(mrb_state *mrb, const char *name)
+{
+  return mrb_interned(mrb, name, strlen(name));
+}
+
+mrb_bool
+mrb_interned(mrb_state *mrb, const char *name, size_t len)
+{
+  khash_t(n2s) *h = mrb->name2sym;
+  symbol_name sname;
+
+  sname.len = len;
+  sname.name = name;
+
+  return (kh_get(n2s, h, sname) != kh_end(h)) ? TRUE : FALSE;
+}
+
+mrb_bool
+mrb_str_interned(mrb_state *mrb, mrb_value str)
+{
+  return mrb_interned(mrb, RSTRING_PTR(str), RSTRING_LEN(str));
+}
+
 /* lenp must be a pointer to a size_t variable */
 const char*
 mrb_sym2name_len(mrb_state *mrb, mrb_sym sym, size_t *lenp)