Merged utility/swap to release branch.

[SVN r49761]

include/boost/swap.hpp

@@ -0,0 +1,12 @@
+// Copyright (C) 2007 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)
+
+#ifndef BOOST_SWAP_HPP
+#define BOOST_SWAP_HPP
+
+#include "boost/utility/swap.hpp"
+
+#endif

include/boost/utility/swap.hpp

@@ -0,0 +1,55 @@
+// Copyright (C) 2007, 2008 Steven Watanabe, Joseph Gauterin, Niels Dekker
+//
+// 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
+
+
+#ifndef BOOST_UTILITY_SWAP_HPP
+#define BOOST_UTILITY_SWAP_HPP
+
+// Note: the implementation of this utility contains various workarounds:
+// - swap_impl is put outside the boost namespace, to avoid infinite
+// recursion (causing stack overflow) when swapping objects of a primitive
+// type.
+// - swap_impl has a using-directive, rather than a using-declaration,
+// because some compilers (including MSVC 7.1, Borland 5.9.3, and
+// Intel 8.1) don't do argument-dependent lookup when it has a
+// using-declaration instead.
+// - boost::swap has two template arguments, instead of one, to
+// avoid ambiguity when swapping objects of a Boost type that does
+// not have its own boost::swap overload.
+
+#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 namespace std;//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
+{
+  template<class T1, class T2>
+  void swap(T1& left, T2& right)
+  {
+    ::boost_swap_impl::swap_impl(left, right);
+  }
+}
+
+#endif