check object type before retrieving instance variabls; close #311

include/mruby/variable.h

@@ -49,6 +49,7 @@ int mrb_const_defined_at(mrb_state *mrb, struct RClass *klass, mrb_sym id);
 mrb_value mrb_f_global_variables(mrb_state *mrb, mrb_value self);
 mrb_value mrb_gv_get(mrb_state *mrb, mrb_sym sym);
 void mrb_gv_set(mrb_state *mrb, mrb_sym sym, mrb_value val);
+mrb_value mrb_obj_instance_variables(mrb_state*, mrb_value);
 
 /* GC functions */
 void mrb_gc_mark_gv(mrb_state*);

src/kernel.c

@@ -708,46 +708,6 @@ mrb_obj_ivar_set(mrb_state *mrb, mrb_value self)
   return val;
 }
 
-/* 15.3.1.3.23 */
-/*
- *  call-seq:
- *     obj.instance_variables    -> array
- *
- *  Returns an array of instance variable names for the receiver. Note
- *  that simply defining an accessor does not create the corresponding
- *  instance variable.
- *
- *     class Fred
- *       attr_accessor :a1
- *       def initialize
- *         @iv = 3
- *       end
- *     end
- *     Fred.new.instance_variables   #=> [:@iv]
- */
-mrb_value
-mrb_obj_instance_variables(mrb_state *mrb, mrb_value self)
-{
-    mrb_value ary;
-    kh_iv_t *h = RCLASS_IV_TBL(self);
-    khint_t i;
-    const char* p;
-
-    ary = mrb_ary_new(mrb);
-    if (h) {
-      for (i=0;i<kh_end(h);i++) {
-        if (kh_exist(h, i)) {
-          p = mrb_sym2name(mrb, kh_key(h,i));
-          if (*p == '@') {
-            if (mrb_type(kh_value(h, i)) != MRB_TT_UNDEF)
-              mrb_ary_push(mrb, ary, mrb_str_new_cstr(mrb, p));
-          }
-        }
-      }
-    }
-    return ary;
-}
-
 /* 15.3.1.3.24 */
 /* 15.3.1.3.26 */
 /*

src/variable.c

@@ -185,6 +185,50 @@ mrb_vm_iv_set(mrb_state *mrb, mrb_sym sym, mrb_value v)
   mrb_iv_set(mrb, mrb->stack[0], sym, v);
 }
 
+/* 15.3.1.3.23 */
+/*
+ *  call-seq:
+ *     obj.instance_variables    -> array
+ *
+ *  Returns an array of instance variable names for the receiver. Note
+ *  that simply defining an accessor does not create the corresponding
+ *  instance variable.
+ *
+ *     class Fred
+ *       attr_accessor :a1
+ *       def initialize
+ *         @iv = 3
+ *       end
+ *     end
+ *     Fred.new.instance_variables   #=> [:@iv]
+ */
+mrb_value
+mrb_obj_instance_variables(mrb_state *mrb, mrb_value self)
+{
+  mrb_value ary;
+  kh_iv_t *h;
+  khint_t i;
+  int len;
+  const char* p;
+
+  ary = mrb_ary_new(mrb);
+  if (obj_iv_p(self)) {
+    h = ROBJECT_IVPTR(self);
+    if (h) {
+      for (i=0;i<kh_end(h);i++) {
+        if (kh_exist(h, i)) {
+          p = mrb_sym2name_len(mrb, kh_key(h,i), &len);
+          if (len > 1 && *p == '@') {
+            if (mrb_type(kh_value(h, i)) != MRB_TT_UNDEF)
+              mrb_ary_push(mrb, ary, mrb_str_new(mrb, p, len));
+          }
+        }
+      }
+    }
+  }
+  return ary;
+}
+
 mrb_value
 mrb_vm_cv_get(mrb_state *mrb, mrb_sym sym)
 {