Moved utility\swap to the trunk, as discussed in trac issue #2056.

[SVN r47093]

include/boost/utility/swap.hpp

@@ -0,0 +1,51 @@
+// Copyright (C) 2007, 2008 Steven Watanabe, Joseph Gauterin
+//
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+// For more information, see http://www.boost.org
+//
+// Update:
+// 29 June 2008 (Added support for built-in arrays.) Niels Dekker  
+
+
+#ifndef BOOST_UTILITY_SWAP_HPP
+#define BOOST_UTILITY_SWAP_HPP
+
+#include <algorithm> //for std::swap
+#include <cstddef> //for std::size_t
+
+namespace boost_swap_impl
+{
+  template<class T>
+  void swap_impl(T& left, T& right)
+  {
+    using std::swap;//use std::swap if argument dependent lookup fails
+    swap(left,right);
+  }
+
+  template<class T, std::size_t N>
+  void swap_impl(T (& left)[N], T (& right)[N])
+  {
+    for (std::size_t i = 0; i < N; ++i)
+    {
+      ::boost_swap_impl::swap_impl(left[i], right[i]);
+    }
+  }
+}
+
+namespace boost
+{
+  namespace swap_adl_barrier
+  {
+    template<class T>
+    void swap(T& left, T& right)
+    {
+      ::boost_swap_impl::swap_impl(left, right);
+    }
+  }
+
+  using swap_adl_barrier::swap;
+}
+
+#endif