From 77c04b0e57c43bc822bfd05dba26687eda754190 Mon Sep 17 00:00:00 2001
From: Dan Marsden <danmarsden@yahoo.co.uk>
Date: Tue, 1 May 2007 20:56:32 +0000
Subject: [PATCH] swap implementation

[SVN r37552]
---
 .../boost/fusion/sequence/intrinsic/swap.hpp  | 59 +++++++++++++++++++
 1 file changed, 59 insertions(+)
 create mode 100644 include/boost/fusion/sequence/intrinsic/swap.hpp

diff --git a/include/boost/fusion/sequence/intrinsic/swap.hpp b/include/boost/fusion/sequence/intrinsic/swap.hpp
new file mode 100644
index 00000000..448ed16b
--- /dev/null
+++ b/include/boost/fusion/sequence/intrinsic/swap.hpp
@@ -0,0 +1,59 @@
+/*=============================================================================
+    Copyright (c) 2001-2006 Joel de Guzman
+    Copyright (c) 2006 Dan Marsden
+
+    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)
+==============================================================================*/
+#if !defined(BOOST_FUSION_SWAP_20070501_1956)
+#define BOOST_FUSION_SWAP_20070501_1956
+
+#include <algorithm>
+
+#include <boost/fusion/support/is_sequence.hpp>
+#include <boost/fusion/sequence/view/zip_view.hpp>
+#include <boost/fusion/algorithm/iteration/for_each.hpp>
+#include <boost/utility/enable_if.hpp>
+#include <boost/fusion/sequence/intrinsic/front.hpp>
+#include <boost/fusion/sequence/intrinsic/back.hpp>
+#include <boost/mpl/and.hpp>
+
+namespace boost { namespace fusion {
+    namespace result_of
+    {
+        template<typename Seq1, typename Seq2>
+        struct swap
+        {
+            typedef void type;
+        };
+    }
+
+    namespace detail
+    {
+        struct swap
+        {
+            template<typename Elem>
+            struct result
+            {
+                typedef void type;
+            };
+
+            template<typename Elem>
+            void operator()(Elem& e) const
+            {
+                using std::swap;
+                swap(front(e), back(e));
+            }
+        };
+    }
+
+    template<typename Seq1, typename Seq2>
+    typename enable_if<mpl::and_<traits::is_sequence<Seq1>, traits::is_sequence<Seq2> >, void>::type 
+    swap(Seq1& lhs, Seq2& rhs)
+    {
+        typedef vector<Seq1&, Seq2&> references;
+        for_each(zip_view<references>(references(lhs, rhs)), detail::swap());
+    }
+}}
+
+#endif