+ /// Direct read access to intermediate elements.
+ T const & operator[](size_type pos) const {
+ return c_[pos];
+ }
+
+ /// Read access to used size.
+ size_type size() const {
+ return c_.size();
+ }
+
+ const_iterator begin() const {
+ return c_.begin();
+ }
+
+ const_iterator end() const {
+ return c_.end();
+ }
+