From 2e77d2e8271cb34324cb1551fbd1f4c3303d74bb Mon Sep 17 00:00:00 2001
From: Kohei Takahashi <flast@flast.jp>
Date: Wed, 17 Oct 2012 19:59:44 +0900
Subject: [PATCH] Support adapting std::tuple to Boost.MPL via Boost.Fusion

---
 boost/fusion/adapted/std_tuple.hpp                 |    2 +
 .../adapted/std_tuple/detail/convert_impl.hpp      |   91 ++++++++++++++++++++
 boost/fusion/adapted/std_tuple/mpl/clear.hpp       |   23 +++++
 3 files changed, 116 insertions(+)
 create mode 100644 boost/fusion/adapted/std_tuple/detail/convert_impl.hpp
 create mode 100644 boost/fusion/adapted/std_tuple/mpl/clear.hpp

diff --git a/boost/fusion/adapted/std_tuple.hpp b/boost/fusion/adapted/std_tuple.hpp
index a49b480..73dcdcd 100644
--- a/boost/fusion/adapted/std_tuple.hpp
+++ b/boost/fusion/adapted/std_tuple.hpp
@@ -15,6 +15,8 @@
 #include <boost/fusion/adapted/std_tuple/detail/size_impl.hpp>
 #include <boost/fusion/adapted/std_tuple/detail/at_impl.hpp>
 #include <boost/fusion/adapted/std_tuple/detail/value_at_impl.hpp>
+#include <boost/fusion/adapted/std_tuple/detail/convert_impl.hpp>
+#include <boost/fusion/adapted/std_tuple/mpl/clear.hpp>
 #include <boost/fusion/adapted/std_tuple/std_tuple_iterator.hpp>
 #include <boost/fusion/adapted/std_tuple/tag_of.hpp>
 
diff --git a/boost/fusion/adapted/std_tuple/detail/convert_impl.hpp b/boost/fusion/adapted/std_tuple/detail/convert_impl.hpp
new file mode 100644
index 0000000..b5b6078
--- /dev/null
+++ b/boost/fusion/adapted/std_tuple/detail/convert_impl.hpp
@@ -0,0 +1,91 @@
+/*=============================================================================
+    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_0940)
+#define BOOST_FUSION_CONVERT_IMPL_10172012_0940
+
+#include <tuple>
+#include <boost/utility/enable_if.hpp>
+#include <boost/mpl/identity.hpp>
+#include <boost/mpl/eval_if.hpp>
+#include <boost/fusion/sequence/intrinsic/begin.hpp>
+#include <boost/fusion/sequence/intrinsic/end.hpp>
+#include <boost/fusion/iterator/equal_to.hpp>
+#include <boost/fusion/iterator/next.hpp>
+#include <boost/fusion/iterator/deref.hpp>
+
+namespace boost { namespace fusion
+{
+    struct std_tuple_tag;
+
+    namespace extension
+    {
+        template <typename T>
+        struct convert_impl;
+
+        template <>
+        struct convert_impl<std_tuple_tag>
+        {
+            template <typename First, typename Last, typename... T>
+            struct expand;
+
+            template <typename First, typename Last, typename... T>
+            struct delay_expanding
+            {
+                typedef typename expand<
+                    typename result_of::next<First>::type
+                  , Last
+                  , T...
+                  , typename result_of::deref<First>::type
+                >::type type;
+            };
+
+            template <typename First, typename Last, typename... T>
+            struct expand
+            {
+                typedef typename mpl::eval_if<
+                    result_of::equal_to<First, Last>
+                  , mpl::identity<std::tuple<T...> >
+                  , delay_expanding<First, Last, T...>
+                >::type type;
+            };
+
+            template <typename Sequence>
+            struct apply
+            {
+                typedef typename expand<
+                    typename result_of::begin<Sequence>::type
+                  , typename result_of::end<Sequence>::type
+                >::type type;
+
+                template <typename I, typename E, typename... T>
+                static typename boost::enable_if<
+                    result_of::equal_to<I, E>
+                  , type
+                >::type call(I& i, E& e, T&... v)
+                {
+                    return type(v...);
+                }
+
+                template <typename I, typename E, typename... T>
+                static typename boost::disable_if<
+                    result_of::equal_to<I, E>
+                  , type
+                >::type call(I& i, E& e, T&... v)
+                {
+                    return call(next(i), e, v..., deref(i));
+                }
+
+                static type call(Sequence& seq)
+                {
+                    return call(begin(seq), end(seq));
+                }
+            };
+        };
+    }
+}}
+
+#endif
diff --git a/boost/fusion/adapted/std_tuple/mpl/clear.hpp b/boost/fusion/adapted/std_tuple/mpl/clear.hpp
new file mode 100644
index 0000000..8712316
--- /dev/null
+++ b/boost/fusion/adapted/std_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_0940)
+#define BOOST_FUSION_CLEAR_10172012_0940
+
+#include <boost/mpl/identity.hpp>
+#include <boost/fusion/adapted/std_tuple/tag_of.hpp>
+
+namespace boost { namespace fusion { namespace detail
+{
+  template <typename Tag>
+  struct clear;
+
+  template <>
+  struct clear<std_tuple_tag> : mpl::identity<std::tuple<> > {};
+
+}}}
+
+#endif
-- 
1.7.9.5