From 43645b376488846794336aaa28c426e9c1eeb34b Mon Sep 17 00:00:00 2001
From: Hartmut Kaiser <hartmut.kaiser@gmail.com>
Date: Fri, 25 Sep 2009 00:20:03 +0000
Subject: [PATCH] Fusion: added nview and friends

[SVN r56376]
---
 include/boost/fusion/include/nview.hpp        | 12 +++
 include/boost/fusion/view/nview.hpp           | 15 ++++
 .../fusion/view/nview/detail/advance_impl.hpp | 49 ++++++++++++
 .../fusion/view/nview/detail/at_impl.hpp      | 45 +++++++++++
 .../fusion/view/nview/detail/begin_impl.hpp   | 49 ++++++++++++
 .../fusion/view/nview/detail/deref_impl.hpp   | 47 +++++++++++
 .../view/nview/detail/distance_impl.hpp       | 44 +++++++++++
 .../fusion/view/nview/detail/end_impl.hpp     | 51 ++++++++++++
 .../view/nview/detail/equal_to_impl.hpp       | 33 ++++++++
 .../fusion/view/nview/detail/next_impl.hpp    | 48 +++++++++++
 .../fusion/view/nview/detail/nview_impl.hpp   | 66 ++++++++++++++++
 .../fusion/view/nview/detail/prior_impl.hpp   | 48 +++++++++++
 .../view/nview/detail/value_at_impl.hpp       | 39 +++++++++
 .../view/nview/detail/value_of_impl.hpp       | 43 ++++++++++
 include/boost/fusion/view/nview/nview.hpp     | 79 +++++++++++++++++++
 .../fusion/view/nview/nview_iterator.hpp      | 53 +++++++++++++
 16 files changed, 721 insertions(+)
 create mode 100644 include/boost/fusion/include/nview.hpp
 create mode 100644 include/boost/fusion/view/nview.hpp
 create mode 100644 include/boost/fusion/view/nview/detail/advance_impl.hpp
 create mode 100644 include/boost/fusion/view/nview/detail/at_impl.hpp
 create mode 100644 include/boost/fusion/view/nview/detail/begin_impl.hpp
 create mode 100644 include/boost/fusion/view/nview/detail/deref_impl.hpp
 create mode 100644 include/boost/fusion/view/nview/detail/distance_impl.hpp
 create mode 100644 include/boost/fusion/view/nview/detail/end_impl.hpp
 create mode 100644 include/boost/fusion/view/nview/detail/equal_to_impl.hpp
 create mode 100644 include/boost/fusion/view/nview/detail/next_impl.hpp
 create mode 100644 include/boost/fusion/view/nview/detail/nview_impl.hpp
 create mode 100644 include/boost/fusion/view/nview/detail/prior_impl.hpp
 create mode 100644 include/boost/fusion/view/nview/detail/value_at_impl.hpp
 create mode 100644 include/boost/fusion/view/nview/detail/value_of_impl.hpp
 create mode 100644 include/boost/fusion/view/nview/nview.hpp
 create mode 100644 include/boost/fusion/view/nview/nview_iterator.hpp

diff --git a/include/boost/fusion/include/nview.hpp b/include/boost/fusion/include/nview.hpp
new file mode 100644
index 00000000..215329d0
--- /dev/null
+++ b/include/boost/fusion/include/nview.hpp
@@ -0,0 +1,12 @@
+/*=============================================================================
+    Copyright (c) 2001-2007 Joel de Guzman
+
+    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(FUSION_INCLUDE_NVIEW)
+#define FUSION_INCLUDE_NVIEW
+
+#include <boost/fusion/view/nview.hpp>
+
+#endif
diff --git a/include/boost/fusion/view/nview.hpp b/include/boost/fusion/view/nview.hpp
new file mode 100644
index 00000000..92e2f26a
--- /dev/null
+++ b/include/boost/fusion/view/nview.hpp
@@ -0,0 +1,15 @@
+/*=============================================================================
+    Copyright (c) 2001-2006 Joel de Guzman
+    Copyright (c) 2006 Dan Marsden
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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(FUSION_NVIEW_SEP_23_2009_1107PM)
+#define FUSION_NVIEW_SEP_23_2009_1107PM
+
+#include <boost/fusion/view/nview/nview.hpp>
+#include <boost/fusion/view/nview/nview_iterator.hpp>
+
+#endif
diff --git a/include/boost/fusion/view/nview/detail/advance_impl.hpp b/include/boost/fusion/view/nview/detail/advance_impl.hpp
new file mode 100644
index 00000000..391bebd8
--- /dev/null
+++ b/include/boost/fusion/view/nview/detail/advance_impl.hpp
@@ -0,0 +1,49 @@
+/*=============================================================================
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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_NVIEW_ADVANCE_IMPL_SEP_24_2009_0212PM)
+#define BOOST_FUSION_NVIEW_ADVANCE_IMPL_SEP_24_2009_0212PM
+
+#include <boost/mpl/advance.hpp>
+#include <boost/fusion/iterator/advance.hpp>
+
+namespace boost { namespace fusion 
+{
+    struct nview_iterator_tag;
+
+    template <typename Sequence, typename Pos>
+    struct nview_iterator;
+
+    namespace extension
+    {
+        template<typename Tag>
+        struct advance_impl;
+
+        template<>
+        struct advance_impl<nview_iterator_tag>
+        {
+            template<typename Iterator, typename Dist>
+            struct apply
+            {
+                typedef typename Iterator::first_type::iterator_type iterator_type;
+                typedef typename Iterator::sequence_type sequence_type;
+
+                typedef nview_iterator<sequence_type, 
+                    typename mpl::advance<iterator_type, Dist>::type> type;
+
+                static type
+                call(Iterator const& i)
+                {
+                    return type(i.seq);
+                }
+            };
+        };
+    }
+
+}}
+
+#endif
diff --git a/include/boost/fusion/view/nview/detail/at_impl.hpp b/include/boost/fusion/view/nview/detail/at_impl.hpp
new file mode 100644
index 00000000..f1f41642
--- /dev/null
+++ b/include/boost/fusion/view/nview/detail/at_impl.hpp
@@ -0,0 +1,45 @@
+/*=============================================================================
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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_NVIEW_AT_IMPL_SEP_24_2009_0225PM)
+#define BOOST_FUSION_NVIEW_AT_IMPL_SEP_24_2009_0225PM
+
+#include <boost/fusion/sequence/intrinsic/at.hpp>
+
+namespace boost { namespace fusion 
+{
+    struct nview_tag;
+
+    namespace extension
+    {
+        template<typename Tag>
+        struct at_impl;
+
+        template<>
+        struct at_impl<nview_tag>
+        {
+            template<typename Sequence, typename N>
+            struct apply
+            {
+                typedef typename Sequence::sequence_type sequence_type;
+                typedef typename Sequence::index_type index_type;
+
+                typedef typename result_of::at<index_type, N>::type index;
+                typedef typename result_of::at<sequence_type, index>::type type;
+
+                static type 
+                call(Sequence& seq)
+                {
+                    return fusion::at<index>(seq.seq);
+                }
+            };
+        };
+    }
+
+}}
+
+#endif
diff --git a/include/boost/fusion/view/nview/detail/begin_impl.hpp b/include/boost/fusion/view/nview/detail/begin_impl.hpp
new file mode 100644
index 00000000..96afe5a8
--- /dev/null
+++ b/include/boost/fusion/view/nview/detail/begin_impl.hpp
@@ -0,0 +1,49 @@
+/*=============================================================================
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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_NVIEW_BEGIN_IMPL_SEP_23_2009_1036PM)
+#define BOOST_FUSION_NVIEW_BEGIN_IMPL_SEP_23_2009_1036PM
+
+#include <boost/mpl/begin.hpp>
+#include <boost/fusion/sequence/intrinsic/begin.hpp>
+
+namespace boost { namespace fusion
+{
+    struct nview_tag;
+
+    template <typename Sequence, typename Pos>
+    struct nview_iterator;
+
+    namespace extension
+    {
+        template<typename Tag>
+        struct begin_impl;
+
+        template<>
+        struct begin_impl<nview_tag>
+        {
+            template<typename Sequence>
+            struct apply
+            {
+                typedef typename Sequence::sequence_type sequence_type;
+                typedef typename Sequence::index_type index_type;
+
+                typedef nview_iterator<sequence_type, 
+                    typename mpl::begin<index_type>::type> type;
+
+                static type call(Sequence& v)
+                {
+                    return type(v.seq);
+                }
+            };
+        };
+    }
+
+}}
+
+#endif
+
diff --git a/include/boost/fusion/view/nview/detail/deref_impl.hpp b/include/boost/fusion/view/nview/detail/deref_impl.hpp
new file mode 100644
index 00000000..329e0842
--- /dev/null
+++ b/include/boost/fusion/view/nview/detail/deref_impl.hpp
@@ -0,0 +1,47 @@
+/*=============================================================================
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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_NVIEW_DEREF_IMPL_SEP_24_2009_0818AM)
+#define BOOST_FUSION_NVIEW_DEREF_IMPL_SEP_24_2009_0818AM
+
+#include <boost/fusion/iterator/deref.hpp>
+#include <boost/fusion/container/vector.hpp>
+
+namespace boost { namespace fusion
+{
+    struct nview_iterator_tag;
+
+    namespace extension
+    {
+        template<typename Tag>
+        struct deref_impl;
+
+        template<>
+        struct deref_impl<nview_iterator_tag>
+        {
+            template<typename Iterator>
+            struct apply
+            {
+                typedef typename Iterator::first_type first_type;
+                typedef typename Iterator::sequence_type sequence_type;
+
+                typedef typename result_of::deref<first_type>::type index;
+                typedef typename result_of::at<sequence_type, index>::type type;
+
+                static type call(Iterator const& i)
+                {
+                    return at<index>(i.seq);
+                }
+            };
+        };
+
+    }
+
+}}
+
+#endif
+
diff --git a/include/boost/fusion/view/nview/detail/distance_impl.hpp b/include/boost/fusion/view/nview/detail/distance_impl.hpp
new file mode 100644
index 00000000..9bc860c5
--- /dev/null
+++ b/include/boost/fusion/view/nview/detail/distance_impl.hpp
@@ -0,0 +1,44 @@
+/*=============================================================================
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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_NVIEW_DISTANCE_IMPL_SEP_23_2009_0328PM)
+#define BOOST_FUSION_NVIEW_DISTANCE_IMPL_SEP_23_2009_0328PM
+
+#include <boost/fusion/iterator/distance.hpp>
+
+namespace boost { namespace fusion 
+{
+    struct nview_iterator_tag;
+
+    namespace extension
+    {
+        template<typename Tag>
+        struct distance_impl;
+
+        template<>
+        struct distance_impl<nview_iterator_tag>
+        {
+            template<typename First, typename Last>
+            struct apply
+              : result_of::distance<typename First::first_type, typename Last::first_type>
+            {
+                typedef typename result_of::distance<
+                    typename First::first_type, typename Last::first_type
+                >::type type;
+
+                static type
+                call(First const& first, Last const& last)
+                {
+                    return type();
+                }
+            };
+        };
+    }
+
+}}
+
+#endif
diff --git a/include/boost/fusion/view/nview/detail/end_impl.hpp b/include/boost/fusion/view/nview/detail/end_impl.hpp
new file mode 100644
index 00000000..d7e87391
--- /dev/null
+++ b/include/boost/fusion/view/nview/detail/end_impl.hpp
@@ -0,0 +1,51 @@
+/*=============================================================================
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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_NVIEW_END_IMPL_SEP_24_2009_0140PM)
+#define BOOST_FUSION_NVIEW_END_IMPL_SEP_24_2009_0140PM
+
+#include <boost/mpl/end.hpp>
+#include <boost/fusion/sequence/intrinsic/end.hpp>
+
+namespace boost { namespace fusion
+{
+    struct nview_tag;
+
+    template <typename Sequence, typename Pos>
+    struct nview_iterator;
+
+    namespace extension
+    {
+        template <typename Tag>
+        struct end_impl;
+
+        // Unary Version
+        template <>
+        struct end_impl<nview_tag>
+        {
+            template <typename Sequence>
+            struct apply
+            {
+                typedef typename Sequence::sequence_type sequence_type;
+                typedef typename Sequence::index_type index_type;
+
+                typedef nview_iterator<sequence_type, 
+                    typename mpl::end<index_type>::type> type;
+
+                static type call(Sequence& v)
+                {
+                    return type(v.seq);
+                }
+            };
+        };
+    }
+
+}}
+
+#endif
+
+
diff --git a/include/boost/fusion/view/nview/detail/equal_to_impl.hpp b/include/boost/fusion/view/nview/detail/equal_to_impl.hpp
new file mode 100644
index 00000000..517204b0
--- /dev/null
+++ b/include/boost/fusion/view/nview/detail/equal_to_impl.hpp
@@ -0,0 +1,33 @@
+/*=============================================================================
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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_NVIEW_ITERATOR_SEP_24_2009_0329PM)
+#define BOOST_FUSION_NVIEW_ITERATOR_SEP_24_2009_0329PM
+
+#include <boost/fusion/iterator/equal_to.hpp>
+
+namespace boost { namespace fusion 
+{
+    struct nview_iterator_tag;
+
+    namespace extension
+    {
+        template<typename Tag>
+        struct equal_to_impl;
+
+        template<>
+        struct equal_to_impl<nview_iterator_tag>
+        {
+            template<typename It1, typename It2>
+            struct apply
+              : result_of::equal_to<typename It1::first_type, typename It2::first_type>
+            {};
+        };
+    }
+}}
+
+#endif
diff --git a/include/boost/fusion/view/nview/detail/next_impl.hpp b/include/boost/fusion/view/nview/detail/next_impl.hpp
new file mode 100644
index 00000000..01cccf2b
--- /dev/null
+++ b/include/boost/fusion/view/nview/detail/next_impl.hpp
@@ -0,0 +1,48 @@
+/*=============================================================================
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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_NVIEW_NEXT_IMPL_SEP_24_2009_0116PM)
+#define BOOST_FUSION_NVIEW_NEXT_IMPL_SEP_24_2009_0116PM
+
+#include <boost/mpl/next.hpp>
+
+namespace boost { namespace fusion
+{
+    struct nview_iterator_tag;
+
+    template <typename Sequence, typename Pos>
+    struct nview_iterator;
+
+    namespace extension
+    {
+        template <typename Tag>
+        struct next_impl;
+
+        template <>
+        struct next_impl<nview_iterator_tag>
+        {
+            template <typename Iterator>
+            struct apply 
+            {
+                typedef typename Iterator::first_type::iterator_type first_type;
+                typedef typename Iterator::sequence_type sequence_type;
+
+                typedef nview_iterator<sequence_type,
+                    typename mpl::next<first_type>::type> type;
+
+                static type
+                call(Iterator const& i)
+                {
+                    return type(i.seq);
+                }
+            };
+        };
+    }
+
+}}
+
+#endif
diff --git a/include/boost/fusion/view/nview/detail/nview_impl.hpp b/include/boost/fusion/view/nview/detail/nview_impl.hpp
new file mode 100644
index 00000000..44263df2
--- /dev/null
+++ b/include/boost/fusion/view/nview/detail/nview_impl.hpp
@@ -0,0 +1,66 @@
+/*=============================================================================
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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_PP_IS_ITERATING
+
+#if !defined(BOOST_FUSION_NVIEW_IMPL_SEP_23_2009_1017PM)
+#define BOOST_FUSION_NVIEW_IMPL_SEP_23_2009_1017PM
+
+#include <boost/preprocessor/cat.hpp>
+#include <boost/preprocessor/repeat.hpp>
+#include <boost/preprocessor/iterate.hpp>
+#include <boost/preprocessor/repetition/enum_params.hpp>
+#include <boost/preprocessor/repetition/enum_binary_params.hpp>
+#include <boost/preprocessor/repetition/enum_params_with_a_default.hpp>
+
+#define BOOST_PP_ITERATION_PARAMS_1                                           \
+    (3, (1, FUSION_MAX_VECTOR_SIZE,                                           \
+    "boost/fusion/view/nview/detail/nview_impl.hpp"))                         \
+    /**/
+
+#include BOOST_PP_ITERATE()
+
+///////////////////////////////////////////////////////////////////////////////
+namespace boost { namespace fusion { namespace result_of
+{
+    template <typename Sequence
+      , BOOST_PP_ENUM_PARAMS_WITH_A_DEFAULT(FUSION_MAX_VECTOR_SIZE, int I, -1)>
+    struct as_nview
+    {
+        typedef mpl::vector_c<
+            int, BOOST_PP_ENUM_PARAMS(FUSION_MAX_VECTOR_SIZE, I)
+        > index_type;
+
+        typedef nview<Sequence, index_type> type;
+    };
+
+}}}
+
+#endif
+
+///////////////////////////////////////////////////////////////////////////////
+//  Preprocessor vertical repetition code
+///////////////////////////////////////////////////////////////////////////////
+#else // defined(BOOST_PP_IS_ITERATING)
+
+#define N BOOST_PP_ITERATION()
+
+namespace boost { namespace fusion
+{
+    template<BOOST_PP_ENUM_PARAMS(N, int I), typename Sequence>
+    inline nview<Sequence, mpl::vector_c<int, BOOST_PP_ENUM_PARAMS(N, I)> >
+    as_nview(Sequence& s)
+    {
+        typedef mpl::vector_c<int, BOOST_PP_ENUM_PARAMS(N, I)> index_type;
+        return nview<Sequence, index_type>(s);
+    }
+
+}}
+
+#undef N
+
+#endif
diff --git a/include/boost/fusion/view/nview/detail/prior_impl.hpp b/include/boost/fusion/view/nview/detail/prior_impl.hpp
new file mode 100644
index 00000000..079a9ca6
--- /dev/null
+++ b/include/boost/fusion/view/nview/detail/prior_impl.hpp
@@ -0,0 +1,48 @@
+/*=============================================================================
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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_NVIEW_PRIOR_IMPL_SEP_24_2009_0142PM)
+#define BOOST_FUSION_NVIEW_PRIOR_IMPL_SEP_24_2009_0142PM
+
+#include <boost/mpl/prior.hpp>
+
+namespace boost { namespace fusion
+{
+    struct nview_iterator_tag;
+
+    template <typename Sequence, typename Pos>
+    struct nview_iterator;
+
+    namespace extension
+    {
+        template <typename Tag>
+        struct prior_impl;
+
+        template <>
+        struct prior_impl<nview_iterator_tag>
+        {
+            template <typename Iterator>
+            struct apply 
+            {
+                typedef typename Iterator::first_type::iterator_type first_type;
+                typedef typename Iterator::sequence_type sequence_type;
+
+                typedef nview_iterator<sequence_type,
+                    typename mpl::prior<first_type>::type> type;
+
+                static type
+                call(Iterator const& i)
+                {
+                    return type(i.seq);
+                }
+            };
+        };
+    }
+
+}}
+
+#endif
diff --git a/include/boost/fusion/view/nview/detail/value_at_impl.hpp b/include/boost/fusion/view/nview/detail/value_at_impl.hpp
new file mode 100644
index 00000000..145bb629
--- /dev/null
+++ b/include/boost/fusion/view/nview/detail/value_at_impl.hpp
@@ -0,0 +1,39 @@
+/*=============================================================================
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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_NVIEW_VALUE_AT_IMPL_SEP_24_2009_0234PM)
+#define BOOST_FUSION_NVIEW_VALUE_AT_IMPL_SEP_24_2009_0234PM
+
+#include <boost/fusion/sequence/intrinsic/value_at.hpp>
+
+namespace boost { namespace fusion 
+{
+    struct nview_tag;
+
+    namespace extension
+    {
+        template<typename Tag>
+        struct value_at_impl;
+
+        template<>
+        struct value_at_impl<nview_tag>
+        {
+            template<typename Sequence, typename N>
+            struct apply
+            {
+                typedef typename Sequence::sequence_type sequence_type;
+                typedef typename Sequence::index_type index_type;
+
+                typedef typename result_of::at<index_type, N>::type index;
+                typedef typename result_of::at<sequence_type, index>::type type;
+            };
+        };
+    }
+
+}}
+
+#endif
diff --git a/include/boost/fusion/view/nview/detail/value_of_impl.hpp b/include/boost/fusion/view/nview/detail/value_of_impl.hpp
new file mode 100644
index 00000000..7af0b1fd
--- /dev/null
+++ b/include/boost/fusion/view/nview/detail/value_of_impl.hpp
@@ -0,0 +1,43 @@
+/*=============================================================================
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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_VALUE_OF_PRIOR_IMPL_SEP_24_2009_0158PM)
+#define BOOST_FUSION_VALUE_OF_PRIOR_IMPL_SEP_24_2009_0158PM
+
+#include <boost/fusion/iterator/deref.hpp>
+#include <boost/fusion/container/vector.hpp>
+
+namespace boost { namespace fusion
+{
+    struct nview_iterator_tag;
+
+    template <typename Sequence, typename Pos>
+    struct nview_iterator;
+
+    namespace extension
+    {
+        template <typename Tag>
+        struct value_of_impl;
+
+        template <>
+        struct value_of_impl<nview_iterator_tag>
+        {
+            template <typename Iterator>
+            struct apply 
+            {
+                typedef typename Iterator::first_type first_type;
+                typedef typename Iterator::sequence_type sequence_type;
+
+                typedef typename result_of::deref<first_type>::type index;
+                typedef typename result_of::at<sequence_type, index>::type type;
+            };
+        };
+    }
+
+}}
+
+#endif
diff --git a/include/boost/fusion/view/nview/nview.hpp b/include/boost/fusion/view/nview/nview.hpp
new file mode 100644
index 00000000..f3011834
--- /dev/null
+++ b/include/boost/fusion/view/nview/nview.hpp
@@ -0,0 +1,79 @@
+/*=============================================================================
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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_NVIEW_SEP_23_2009_0948PM)
+#define BOOST_FUSION_NVIEW_SEP_23_2009_0948PM
+
+#include <boost/mpl/size.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/vector_c.hpp>
+#include <boost/utility/result_of.hpp>
+
+#include <boost/type_traits/remove_reference.hpp>
+
+#include <boost/fusion/support/is_view.hpp>
+#include <boost/fusion/support/category_of.hpp>
+#include <boost/fusion/support/sequence_base.hpp>
+#include <boost/fusion/container/vector.hpp>
+#include <boost/fusion/view/transform_view.hpp>
+
+namespace boost { namespace fusion
+{
+    namespace detail
+    {
+        struct addref
+        {
+            template<typename Sig>
+            struct result;
+
+            template<typename U>
+            struct result<addref(U)> : boost::add_reference<U> {};
+
+            template <typename T>
+            typename boost::result_of<addref(T)>::type 
+            operator()(T& x) const
+            {
+                return x;
+            }
+        };
+    }
+
+    struct nview_tag;
+    struct random_access_traversal_tag;
+    struct fusion_sequence_tag;
+
+    template<typename Sequence, typename Indicies>
+    struct nview
+      : sequence_base<nview<Sequence, Indicies> >
+    {
+        typedef nview_tag fusion_tag;
+        typedef fusion_sequence_tag tag; // this gets picked up by MPL
+        typedef random_access_traversal_tag category;
+
+        typedef mpl::true_ is_view;
+        typedef Indicies index_type;
+        typedef typename mpl::size<Indicies>::type size;
+
+        typedef transform_view<Sequence, detail::addref> transform_view_type;
+        typedef typename result_of::as_vector<transform_view_type>::type 
+            sequence_type;
+
+        explicit nview(Sequence& val)
+          : seq(as_vector(transform_view_type(val, detail::addref()))) 
+        {}
+
+        sequence_type seq;
+    };
+
+}}
+
+// define the nview() generator functions
+#include <boost/fusion/view/nview/detail/nview_impl.hpp>
+
+#endif
+
+
diff --git a/include/boost/fusion/view/nview/nview_iterator.hpp b/include/boost/fusion/view/nview/nview_iterator.hpp
new file mode 100644
index 00000000..12580749
--- /dev/null
+++ b/include/boost/fusion/view/nview/nview_iterator.hpp
@@ -0,0 +1,53 @@
+/*=============================================================================
+    Copyright (c) 2009 Hartmut Kaiser
+
+    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_NVIEW_ITERATOR_SEP_23_2009_0948PM)
+#define BOOST_FUSION_NVIEW_ITERATOR_SEP_23_2009_0948PM
+
+#include <boost/fusion/support/iterator_base.hpp>
+#include <boost/fusion/support/category_of.hpp>
+#include <boost/fusion/sequence/intrinsic/begin.hpp>
+#include <boost/fusion/sequence/intrinsic/end.hpp>
+#include <boost/fusion/adapted/mpl/mpl_iterator.hpp>
+
+#include <boost/fusion/view/nview/detail/begin_impl.hpp>
+#include <boost/fusion/view/nview/detail/end_impl.hpp>
+#include <boost/fusion/view/nview/detail/deref_impl.hpp>
+#include <boost/fusion/view/nview/detail/value_of_impl.hpp>
+#include <boost/fusion/view/nview/detail/next_impl.hpp>
+#include <boost/fusion/view/nview/detail/prior_impl.hpp>
+#include <boost/fusion/view/nview/detail/at_impl.hpp>
+#include <boost/fusion/view/nview/detail/value_at_impl.hpp>
+#include <boost/fusion/view/nview/detail/advance_impl.hpp>
+#include <boost/fusion/view/nview/detail/distance_impl.hpp>
+#include <boost/fusion/view/nview/detail/equal_to_impl.hpp>
+
+namespace boost { namespace fusion
+{
+    struct nview_iterator_tag;
+    struct random_access_traversal_tag;
+
+    template<typename Sequence, typename Pos>
+    struct nview_iterator
+      : iterator_base<nview_iterator<Sequence, Pos> >
+    {
+        typedef nview_iterator_tag fusion_tag;
+        typedef random_access_traversal_tag category;
+
+        typedef Sequence sequence_type;
+        typedef mpl_iterator<Pos> first_type;
+
+        explicit nview_iterator(Sequence& seq)
+          : seq(seq) {}
+
+        Sequence& seq;
+    };
+
+}}
+
+#endif
+
+