+
+ /**
+ * @brief Swaps two values.
+ * @param a A thing of arbitrary type.
+ * @param b Another thing of arbitrary type.
+ * @return Nothing.
+ *
+ * This is the simple classic generic implementation. It will work on
+ * any type which has a copy constructor and an assignment operator.
+ */
+ template<typename _Tp>
+ inline void
+ swap(_Tp& __a, _Tp& __b)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
+
+ const _Tp __tmp = __a;
+ __a = __b;
+ __b = __tmp;
+ }
+
+ // See http://gcc.gnu.org/ml/libstdc++/2004-08/msg00167.html: in a
+ // nutshell, we are partially implementing the resolution of DR 187,
+ // when it's safe, i.e., the value_types are equal.
+ template<bool _BoolType>
+ struct __iter_swap
+ {
+ template<typename _ForwardIterator1, typename _ForwardIterator2>
+ static void
+ iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
+ {
+ typedef typename iterator_traits<_ForwardIterator1>::value_type
+ _ValueType1;
+ const _ValueType1 __tmp = *__a;
+ *__a = *__b;
+ *__b = __tmp;
+ }
+ };
+
+ template<>
+ struct __iter_swap<true>
+ {
+ template<typename _ForwardIterator1, typename _ForwardIterator2>
+ static void
+ iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
+ {
+ swap(*__a, *__b);
+ }
+ };
+