From 6e2bfab3fda26abf264c9b4578b6e0ba41e3d20a Mon Sep 17 00:00:00 2001
From: Kohei Takahashi <flast@flast.jp>
Date: Wed, 17 Oct 2012 18:05:39 +0900
Subject: [PATCH] Support adapting Boost.Tuple to Boost.MPL via Boost.Fusion

---
 boost/fusion/adapted/boost_tuple.hpp               |    3 ++
 .../adapted/boost_tuple/detail/build_cons.hpp      |   57 ++++++++++++++++++++
 .../adapted/boost_tuple/detail/convert_impl.hpp    |   48 +++++++++++++++++
 boost/fusion/adapted/boost_tuple/mpl/clear.hpp     |   23 ++++++++
 4 files changed, 131 insertions(+)
 create mode 100644 boost/fusion/adapted/boost_tuple/detail/build_cons.hpp
 create mode 100644 boost/fusion/adapted/boost_tuple/detail/convert_impl.hpp
 create mode 100644 boost/fusion/adapted/boost_tuple/mpl/clear.hpp

diff --git a/boost/fusion/adapted/boost_tuple.hpp b/boost/fusion/adapted/boost_tuple.hpp
index 6149478..88eada1 100644
--- a/boost/fusion/adapted/boost_tuple.hpp
+++ b/boost/fusion/adapted/boost_tuple.hpp
@@ -1,5 +1,6 @@
 /*=============================================================================
     Copyright (c) 2001-2011 Joel de Guzman
+    Copyright (c) 2012 Kohei Takahashi
 
     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)
@@ -16,5 +17,7 @@
 #include <boost/fusion/adapted/boost_tuple/detail/size_impl.hpp>
 #include <boost/fusion/adapted/boost_tuple/detail/at_impl.hpp>
 #include <boost/fusion/adapted/boost_tuple/detail/value_at_impl.hpp>
+#include <boost/fusion/adapted/boost_tuple/detail/convert_impl.hpp>
+#include <boost/fusion/adapted/boost_tuple/mpl/clear.hpp>
 
 #endif
diff --git a/boost/fusion/adapted/boost_tuple/detail/build_cons.hpp b/boost/fusion/adapted/boost_tuple/detail/build_cons.hpp
new file mode 100644
index 0000000..9e2673e
--- /dev/null
+++ b/boost/fusion/adapted/boost_tuple/detail/build_cons.hpp
@@ -0,0 +1,57 @@
+/*=============================================================================
+    Copyright (c) 2012 Kohei Takahashi
+
+    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_BUILD_CONS_10172012_0130)
+#define BOOST_FUSION_BUILD_CONS_10172012_0130
+
+#include <boost/tuple/tuple.hpp>
+#include <boost/fusion/iterator/equal_to.hpp>
+#include <boost/fusion/iterator/next.hpp>
+#include <boost/fusion/iterator/value_of.hpp>
+#include <boost/fusion/iterator/deref.hpp>
+
+namespace boost { namespace fusion { namespace detail
+{
+    template <
+        typename First
+      , typename Last
+      , bool is_empty = result_of::equal_to<First, Last>::value>
+    struct build_cons;
+
+    template <typename First, typename Last>
+    struct build_cons<First, Last, true>
+    {
+        typedef boost::tuples::null_type type;
+
+        static type
+        call(First const&, Last const&)
+        {
+            return type();
+        }
+    };
+
+    template <typename First, typename Last>
+    struct build_cons<First, Last, false>
+    {
+        typedef
+            build_cons<typename result_of::next<First>::type, Last>
+        next_build_cons;
+
+        typedef boost::tuples::cons<
+            typename result_of::value_of<First>::type
+          , typename next_build_cons::type>
+        type;
+
+        static type
+        call(First const& f, Last const& l)
+        {
+            typename result_of::value_of<First>::type v = *f;
+            return type(v, next_build_cons::call(fusion::next(f), l));
+        }
+    };
+}}}
+
+#endif
diff --git a/boost/fusion/adapted/boost_tuple/detail/convert_impl.hpp b/boost/fusion/adapted/boost_tuple/detail/convert_impl.hpp
new file mode 100644
index 0000000..e099981
--- /dev/null
+++ b/boost/fusion/adapted/boost_tuple/detail/convert_impl.hpp
@@ -0,0 +1,48 @@
+/*=============================================================================
+    Copyright (c) 2012 Kohei Takahashi
+
+    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_CONVERT_IMPL_10172012_0120)
+#define BOOST_FUSION_CONVERT_IMPL_10172012_0120
+
+#include <boost/tuple/tuple.hpp>
+#include <boost/fusion/adapted/boost_tuple/detail/build_cons.hpp>
+#include <boost/fusion/sequence/intrinsic/begin.hpp>
+#include <boost/fusion/sequence/intrinsic/end.hpp>
+
+namespace boost { namespace fusion
+{
+    struct boost_tuple_tag;
+
+    namespace extension
+    {
+        template <typename T>
+        struct convert_impl;
+
+        template <>
+        struct convert_impl<boost_tuple_tag>
+        {
+            template <typename Sequence>
+            struct apply
+            {
+                typedef typename
+                    detail::build_cons<
+                        typename result_of::begin<Sequence>::type
+                      , typename result_of::end<Sequence>::type
+                    >
+                build_cons;
+
+                typedef typename build_cons::type type;
+
+                static type call(Sequence& seq)
+                {
+                    return build_cons::call(fusion::begin(seq), fusion::end(seq));
+                }
+            };
+        };
+    }
+}}
+
+#endif
diff --git a/boost/fusion/adapted/boost_tuple/mpl/clear.hpp b/boost/fusion/adapted/boost_tuple/mpl/clear.hpp
new file mode 100644
index 0000000..1cca019
--- /dev/null
+++ b/boost/fusion/adapted/boost_tuple/mpl/clear.hpp
@@ -0,0 +1,23 @@
+/*=============================================================================
+    Copyright (c) 2012 Kohei Takahashi
+
+    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_CLEAR_10172012_0100)
+#define BOOST_FUSION_CLEAR_10172012_0100
+
+#include <boost/mpl/identity.hpp>
+#include <boost/fusion/adapted/boost_tuple/tag_of.hpp>
+
+namespace boost { namespace fusion { namespace detail {
+
+  template <typename Tag>
+  struct clear;
+
+  template <>
+  struct clear<boost_tuple_tag> : mpl::identity<boost::tuple<> > {};
+
+}}}
+
+#endif
-- 
1.7.9.5