From 6002bc9bb4d1c219994d3dc459bf201352567e89 Mon Sep 17 00:00:00 2001
From: Joel de Guzman <djowel@gmail.com>
Date: Mon, 2 Apr 2007 03:31:13 +0000
Subject: [PATCH] added struct wrapping facilities to make it very easy to make
 any struct a conforming fusion sequence

[SVN r37328]
---
 include/boost/fusion/sequence/adapted/mpl.hpp |   3 +-
 .../fusion/sequence/adapted/std_pair.hpp      |  65 ++++++++--
 .../adapted/std_pair/Attic/tag_of.hpp         |  29 -----
 .../boost/fusion/sequence/adapted/struct.hpp  |  20 ++++
 .../Attic => struct/detail}/at_impl.hpp       |  50 ++++----
 .../Attic => struct/detail}/begin_impl.hpp    |  18 +--
 .../detail}/category_of_impl.hpp              |  10 +-
 .../Attic => struct/detail}/end_impl.hpp      |  18 +--
 .../detail}/is_sequence_impl.hpp              |  10 +-
 .../Attic => struct/detail}/is_view_impl.hpp  |   8 +-
 .../Attic => struct/detail}/size_impl.hpp     |  16 ++-
 .../Attic => struct/detail}/value_at_impl.hpp |  28 +++--
 .../struct_iterator.hpp}                      | 111 +++++++++---------
 13 files changed, 214 insertions(+), 172 deletions(-)
 delete mode 100644 include/boost/fusion/sequence/adapted/std_pair/Attic/tag_of.hpp
 create mode 100644 include/boost/fusion/sequence/adapted/struct.hpp
 rename include/boost/fusion/sequence/adapted/{std_pair/detail/Attic => struct/detail}/at_impl.hpp (57%)
 rename include/boost/fusion/sequence/adapted/{std_pair/detail/Attic => struct/detail}/begin_impl.hpp (74%)
 rename include/boost/fusion/sequence/adapted/{std_pair/detail/Attic => struct/detail}/category_of_impl.hpp (86%)
 rename include/boost/fusion/sequence/adapted/{std_pair/detail/Attic => struct/detail}/end_impl.hpp (74%)
 rename include/boost/fusion/sequence/adapted/{std_pair/detail/Attic => struct/detail}/is_sequence_impl.hpp (85%)
 rename include/boost/fusion/sequence/adapted/{std_pair/detail/Attic => struct/detail}/is_view_impl.hpp (86%)
 rename include/boost/fusion/sequence/adapted/{std_pair/detail/Attic => struct/detail}/size_impl.hpp (71%)
 rename include/boost/fusion/sequence/adapted/{std_pair/detail/Attic => struct/detail}/value_at_impl.hpp (65%)
 rename include/boost/fusion/sequence/adapted/{std_pair/Attic/std_pair_iterator.hpp => struct/struct_iterator.hpp} (51%)

diff --git a/include/boost/fusion/sequence/adapted/mpl.hpp b/include/boost/fusion/sequence/adapted/mpl.hpp
index 643a587c..94f4967a 100644
--- a/include/boost/fusion/sequence/adapted/mpl.hpp
+++ b/include/boost/fusion/sequence/adapted/mpl.hpp
@@ -2,13 +2,12 @@
     Copyright (c) 2001-2006 Joel de Guzman
     Copyright (c) 2005-2006 Dan Marsden
 
-    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    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_MPL_31122005_1152)
 #define BOOST_FUSION_MPL_31122005_1152
 
-#include <boost/fusion/sequence/adapted/mpl/mpl_iterator.hpp>
 #include <boost/fusion/sequence/adapted/mpl/detail/begin_impl.hpp>
 #include <boost/fusion/sequence/adapted/mpl/detail/end_impl.hpp>
 #include <boost/fusion/sequence/adapted/mpl/detail/is_sequence_impl.hpp>
diff --git a/include/boost/fusion/sequence/adapted/std_pair.hpp b/include/boost/fusion/sequence/adapted/std_pair.hpp
index d4ba0b68..0b755a0b 100644
--- a/include/boost/fusion/sequence/adapted/std_pair.hpp
+++ b/include/boost/fusion/sequence/adapted/std_pair.hpp
@@ -2,20 +2,65 @@
     Copyright (c) 2001-2006 Joel de Guzman
     Copyright (c) 2005-2006 Dan Marsden
 
-    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    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_STD_PAIR_24122005_1744)
 #define BOOST_FUSION_STD_PAIR_24122005_1744
 
-#include <boost/fusion/sequence/adapted/std_pair/tag_of.hpp>
-#include <boost/fusion/sequence/adapted/std_pair/detail/is_view_impl.hpp>
-#include <boost/fusion/sequence/adapted/std_pair/detail/is_sequence_impl.hpp>
-#include <boost/fusion/sequence/adapted/std_pair/detail/category_of_impl.hpp>
-#include <boost/fusion/sequence/adapted/std_pair/detail/begin_impl.hpp>
-#include <boost/fusion/sequence/adapted/std_pair/detail/end_impl.hpp>
-#include <boost/fusion/sequence/adapted/std_pair/detail/size_impl.hpp>
-#include <boost/fusion/sequence/adapted/std_pair/detail/at_impl.hpp>
-#include <boost/fusion/sequence/adapted/std_pair/detail/value_at_impl.hpp>
+#include <boost/fusion/support/tag_of_fwd.hpp>
+#include <boost/fusion/sequence/adapted/struct.hpp>
+#include <boost/mpl/int.hpp>
+#include <utility>
+
+namespace boost { namespace fusion
+{
+    struct struct_tag;
+
+    namespace traits
+    {
+        template <typename T1, typename T2>
+        struct tag_of<std::pair<T1, T2> >
+        {
+            typedef struct_tag type;
+        };
+    }
+
+    namespace extension
+    {
+        template <typename Struct, int N>
+        struct struct_member;
+
+        template <typename Struct>
+        struct struct_size;
+
+        template <typename T1, typename T2>
+        struct struct_member<std::pair<T1, T2>, 0>
+        {
+            typedef T1 type;
+
+            static type& call(std::pair<T1, T2>& pair)
+            {
+                return pair.first;
+            }
+        };
+
+        template <typename T1, typename T2>
+        struct struct_member<std::pair<T1, T2>, 1>
+        {
+            typedef T2 type;
+
+            static type& call(std::pair<T1, T2>& pair)
+            {
+                return pair.second;
+            }
+        };
+
+        template <typename T1, typename T2>
+        struct struct_size<std::pair<T1, T2> > : mpl::int_<2>
+        {
+        };
+    }
+}}
 
 #endif
diff --git a/include/boost/fusion/sequence/adapted/std_pair/Attic/tag_of.hpp b/include/boost/fusion/sequence/adapted/std_pair/Attic/tag_of.hpp
deleted file mode 100644
index 3211efad..00000000
--- a/include/boost/fusion/sequence/adapted/std_pair/Attic/tag_of.hpp
+++ /dev/null
@@ -1,29 +0,0 @@
-/*=============================================================================
-    Copyright (c) 2001-2006 Joel de Guzman
-    Copyright (c) 2005-2006 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_TAG_OF_24122005_1722)
-#define BOOST_FUSION_TAG_OF_24122005_1722
-
-#include <boost/fusion/support/tag_of_fwd.hpp>
-
-#include <utility>
-
-namespace boost { namespace fusion {
-
-    struct std_pair_tag;
-
-    namespace traits
-    {
-        template<typename T1, typename T2>
-        struct tag_of<std::pair<T1, T2> >
-        {
-            typedef std_pair_tag type;
-        };
-    }
-}}
-
-#endif
diff --git a/include/boost/fusion/sequence/adapted/struct.hpp b/include/boost/fusion/sequence/adapted/struct.hpp
new file mode 100644
index 00000000..1b52fd7c
--- /dev/null
+++ b/include/boost/fusion/sequence/adapted/struct.hpp
@@ -0,0 +1,20 @@
+/*=============================================================================
+    Copyright (c) 2001-2006 Joel de Guzman
+    Copyright (c) 2005-2006 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_STRUCT_24122005_1744)
+#define BOOST_FUSION_STD_STRUCT_24122005_1744
+
+#include <boost/fusion/sequence/adapted/struct/detail/is_view_impl.hpp>
+#include <boost/fusion/sequence/adapted/struct/detail/is_sequence_impl.hpp>
+#include <boost/fusion/sequence/adapted/struct/detail/category_of_impl.hpp>
+#include <boost/fusion/sequence/adapted/struct/detail/begin_impl.hpp>
+#include <boost/fusion/sequence/adapted/struct/detail/end_impl.hpp>
+#include <boost/fusion/sequence/adapted/struct/detail/size_impl.hpp>
+#include <boost/fusion/sequence/adapted/struct/detail/at_impl.hpp>
+#include <boost/fusion/sequence/adapted/struct/detail/value_at_impl.hpp>
+
+#endif
diff --git a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/at_impl.hpp b/include/boost/fusion/sequence/adapted/struct/detail/at_impl.hpp
similarity index 57%
rename from include/boost/fusion/sequence/adapted/std_pair/detail/Attic/at_impl.hpp
rename to include/boost/fusion/sequence/adapted/struct/detail/at_impl.hpp
index 2f26fa68..809902ae 100644
--- a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/at_impl.hpp
+++ b/include/boost/fusion/sequence/adapted/struct/detail/at_impl.hpp
@@ -2,40 +2,43 @@
     Copyright (c) 2001-2006 Joel de Guzman
     Copyright (c) 2005-2006 Dan Marsden
 
-    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    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_AT_IMPL_24122005_1807)
 #define BOOST_FUSION_AT_IMPL_24122005_1807
 
-#include <boost/mpl/if.hpp>
-#include <boost/mpl/int.hpp>
-#include <boost/static_assert.hpp>
 #include <boost/fusion/support/detail/access.hpp>
+#include <boost/mpl/assert.hpp>
+#include <boost/mpl/int.hpp>
 
-namespace boost { namespace fusion {
-
-    struct std_pair_tag;
+namespace boost { namespace fusion
+{
+    struct struct_tag;
 
     namespace extension
     {
         template<typename T>
         struct at_impl;
 
+        template <typename Struct, int N>
+        struct struct_member;
+
+        template <typename Struct>
+        struct struct_size;
+
         template <>
-        struct at_impl<std_pair_tag>
+        struct at_impl<struct_tag>
         {
             template <typename Sequence, typename N>
-            struct apply 
+            struct apply
             {
                 static int const n_value = N::value;
-                BOOST_STATIC_ASSERT((n_value >= 0 && n_value < 2));
+                BOOST_MPL_ASSERT_RELATION(
+                    n_value, <=, extension::struct_size<Sequence>::value);
+
                 typedef typename
-                    mpl::if_c<
-                        (n_value == 0)
-                      , typename Sequence::first_type
-                      , typename Sequence::second_type
-                    >
+                    extension::struct_member<Sequence, N::value>
                 element;
 
                 typedef typename
@@ -46,22 +49,11 @@ namespace boost { namespace fusion {
                     >::type
                 type;
 
-                template <typename RT>
-                static RT get(Sequence& p, mpl::int_<0>)
-                {
-                    return  p.first;
-                }
-
-                template <typename RT>
-                static RT get(Sequence& p, mpl::int_<1>)
-                {
-                    return  p.second;
-                }
-
                 static type
-                call(Sequence& p)
+                call(Sequence& seq)
                 {
-                    return get<type>(p, N());
+                    return extension::
+                        struct_member<Sequence, N::value>::call(seq);
                 }
             };
         };
diff --git a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/begin_impl.hpp b/include/boost/fusion/sequence/adapted/struct/detail/begin_impl.hpp
similarity index 74%
rename from include/boost/fusion/sequence/adapted/std_pair/detail/Attic/begin_impl.hpp
rename to include/boost/fusion/sequence/adapted/struct/detail/begin_impl.hpp
index 1b77b7a7..14817726 100644
--- a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/begin_impl.hpp
+++ b/include/boost/fusion/sequence/adapted/struct/detail/begin_impl.hpp
@@ -2,17 +2,17 @@
     Copyright (c) 2001-2006 Joel de Guzman
     Copyright (c) 2005-2006 Dan Marsden
 
-    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    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_BEGIN_IMPL_24122005_1752)
 #define BOOST_FUSION_BEGIN_IMPL_24122005_1752
 
-#include <boost/fusion/sequence/adapted/std_pair/std_pair_iterator.hpp>
+#include <boost/fusion/sequence/adapted/struct/struct_iterator.hpp>
 
-namespace boost { namespace fusion {
-
-    struct std_pair_tag;
+namespace boost { namespace fusion
+{
+    struct struct_tag;
 
     namespace extension
     {
@@ -20,13 +20,13 @@ namespace boost { namespace fusion {
         struct begin_impl;
 
         template <>
-        struct begin_impl<std_pair_tag>
+        struct begin_impl<struct_tag>
         {
             template <typename Sequence>
-            struct apply 
+            struct apply
             {
-                typedef std_pair_iterator<Sequence, 0> type;
-    
+                typedef struct_iterator<Sequence, 0> type;
+
                 static type
                 call(Sequence& v)
                 {
diff --git a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/category_of_impl.hpp b/include/boost/fusion/sequence/adapted/struct/detail/category_of_impl.hpp
similarity index 86%
rename from include/boost/fusion/sequence/adapted/std_pair/detail/Attic/category_of_impl.hpp
rename to include/boost/fusion/sequence/adapted/struct/detail/category_of_impl.hpp
index f207c1c7..9e7f9df4 100644
--- a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/category_of_impl.hpp
+++ b/include/boost/fusion/sequence/adapted/struct/detail/category_of_impl.hpp
@@ -2,7 +2,7 @@
     Copyright (c) 2001-2006 Joel de Guzman
     Copyright (c) 2005-2006 Dan Marsden
 
-    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    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_CATEGORY_OF_IMPL_24122005_1731)
@@ -10,9 +10,9 @@
 
 #include <utility>
 
-namespace boost { namespace fusion { 
-
-    struct std_pair_tag;
+namespace boost { namespace fusion
+{
+    struct struct_tag;
     struct random_access_traversal_tag;
 
     namespace extension
@@ -21,7 +21,7 @@ namespace boost { namespace fusion {
         struct category_of_impl;
 
         template<>
-        struct category_of_impl<std_pair_tag>
+        struct category_of_impl<struct_tag>
         {
             template<typename T>
             struct apply
diff --git a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/end_impl.hpp b/include/boost/fusion/sequence/adapted/struct/detail/end_impl.hpp
similarity index 74%
rename from include/boost/fusion/sequence/adapted/std_pair/detail/Attic/end_impl.hpp
rename to include/boost/fusion/sequence/adapted/struct/detail/end_impl.hpp
index 9aab76c5..91830cea 100644
--- a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/end_impl.hpp
+++ b/include/boost/fusion/sequence/adapted/struct/detail/end_impl.hpp
@@ -2,17 +2,17 @@
     Copyright (c) 2001-2006 Joel de Guzman
     Copyright (c) 2005-2006 Dan Marsden
 
-    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    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_END_IMPL_24122005_1755)
 #define BOOST_FUSION_END_IMPL_24122005_1755
 
-#include <boost/fusion/sequence/adapted/std_pair/std_pair_iterator.hpp>
+#include <boost/fusion/sequence/adapted/struct/struct_iterator.hpp>
 
-namespace boost { namespace fusion {
-
-    struct std_pair_tag;
+namespace boost { namespace fusion
+{
+    struct struct_tag;
 
     namespace extension
     {
@@ -20,13 +20,13 @@ namespace boost { namespace fusion {
         struct end_impl;
 
         template <>
-        struct end_impl<std_pair_tag>
+        struct end_impl<struct_tag>
         {
             template <typename Sequence>
-            struct apply 
+            struct apply
             {
-                typedef std_pair_iterator<Sequence, 2> type;
-    
+                typedef struct_iterator<Sequence, 2> type;
+
                 static type
                 call(Sequence& v)
                 {
diff --git a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/is_sequence_impl.hpp b/include/boost/fusion/sequence/adapted/struct/detail/is_sequence_impl.hpp
similarity index 85%
rename from include/boost/fusion/sequence/adapted/std_pair/detail/Attic/is_sequence_impl.hpp
rename to include/boost/fusion/sequence/adapted/struct/detail/is_sequence_impl.hpp
index 1c669a68..f81e9fb6 100644
--- a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/is_sequence_impl.hpp
+++ b/include/boost/fusion/sequence/adapted/struct/detail/is_sequence_impl.hpp
@@ -2,7 +2,7 @@
     Copyright (c) 2001-2006 Joel de Guzman
     Copyright (c) 2005-2006 Dan Marsden
 
-    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    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_IS_SEQUENCE_IMPL_27122005_1651)
@@ -10,9 +10,9 @@
 
 #include <boost/mpl/bool.hpp>
 
-namespace boost { namespace fusion {
-
-    struct std_pair_tag;
+namespace boost { namespace fusion
+{
+    struct struct_tag;
 
     namespace extension
     {
@@ -20,7 +20,7 @@ namespace boost { namespace fusion {
         struct is_sequence_impl;
 
         template<>
-        struct is_sequence_impl<std_pair_tag>
+        struct is_sequence_impl<struct_tag>
         {
             template<typename Sequence>
             struct apply : mpl::true_ {};
diff --git a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/is_view_impl.hpp b/include/boost/fusion/sequence/adapted/struct/detail/is_view_impl.hpp
similarity index 86%
rename from include/boost/fusion/sequence/adapted/std_pair/detail/Attic/is_view_impl.hpp
rename to include/boost/fusion/sequence/adapted/struct/detail/is_view_impl.hpp
index 94842bc0..da6f380b 100644
--- a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/is_view_impl.hpp
+++ b/include/boost/fusion/sequence/adapted/struct/detail/is_view_impl.hpp
@@ -2,7 +2,7 @@
     Copyright (c) 2001-2006 Joel de Guzman
     Copyright (c) 2005-2006 Dan Marsden
 
-    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    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_IS_VIEW_IMPL_27042006_2219)
@@ -10,9 +10,9 @@
 
 #include <boost/mpl/bool.hpp>
 
-namespace boost { namespace fusion 
+namespace boost { namespace fusion
 {
-    struct std_pair_tag;
+    struct struct_tag;
 
     namespace extension
     {
@@ -20,7 +20,7 @@ namespace boost { namespace fusion
         struct is_view_impl;
 
         template<>
-        struct is_view_impl<std_pair_tag>
+        struct is_view_impl<struct_tag>
         {
             template<typename T>
             struct apply : mpl::false_
diff --git a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/size_impl.hpp b/include/boost/fusion/sequence/adapted/struct/detail/size_impl.hpp
similarity index 71%
rename from include/boost/fusion/sequence/adapted/std_pair/detail/Attic/size_impl.hpp
rename to include/boost/fusion/sequence/adapted/struct/detail/size_impl.hpp
index 5f35bffd..12ec14ba 100644
--- a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/size_impl.hpp
+++ b/include/boost/fusion/sequence/adapted/struct/detail/size_impl.hpp
@@ -2,7 +2,7 @@
     Copyright (c) 2001-2006 Joel de Guzman
     Copyright (c) 2005-2006 Dan Marsden
 
-    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    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_SIZE_IMPL_24122005_1759)
@@ -10,9 +10,15 @@
 
 #include <boost/mpl/int.hpp>
 
-namespace boost { namespace fusion {
+namespace boost { namespace fusion
+{
+    namespace extension
+    {
+        template <typename Struct>
+        struct struct_size;
+    }
 
-    struct std_pair_tag;
+    struct struct_tag;
 
     namespace extension
     {
@@ -20,10 +26,10 @@ namespace boost { namespace fusion {
         struct size_impl;
 
         template <>
-        struct size_impl<std_pair_tag>
+        struct size_impl<struct_tag>
         {
             template <typename Sequence>
-            struct apply : mpl::int_<2> {};
+            struct apply : extension::struct_size<Sequence> {};
         };
     }
 }}
diff --git a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/value_at_impl.hpp b/include/boost/fusion/sequence/adapted/struct/detail/value_at_impl.hpp
similarity index 65%
rename from include/boost/fusion/sequence/adapted/std_pair/detail/Attic/value_at_impl.hpp
rename to include/boost/fusion/sequence/adapted/struct/detail/value_at_impl.hpp
index 16047ec9..8f5d97a0 100644
--- a/include/boost/fusion/sequence/adapted/std_pair/detail/Attic/value_at_impl.hpp
+++ b/include/boost/fusion/sequence/adapted/struct/detail/value_at_impl.hpp
@@ -2,7 +2,7 @@
     Copyright (c) 2001-2006 Joel de Guzman
     Copyright (c) 2005-2006 Dan Marsden
 
-    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    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_AT_IMPL_24122005_1917)
@@ -11,29 +11,33 @@
 #include <boost/mpl/if.hpp>
 #include <boost/static_assert.hpp>
 
-namespace boost { namespace fusion {
-
-    struct std_pair_tag;
+namespace boost { namespace fusion
+{
+    struct struct_tag;
 
     namespace extension
     {
         template<typename T>
         struct value_at_impl;
 
+        template <typename Struct, int N>
+        struct struct_member;
+
+        template <typename Struct>
+        struct struct_size;
+
         template <>
-        struct value_at_impl<std_pair_tag>
+        struct value_at_impl<struct_tag>
         {
             template <typename Sequence, typename N>
-            struct apply 
+            struct apply
             {
                 static int const n_value = N::value;
-                BOOST_STATIC_ASSERT((n_value >= 0 && n_value < 2));
+                BOOST_MPL_ASSERT_RELATION(
+                    n_value, <=, extension::struct_size<Sequence>::value);
+
                 typedef typename
-                    mpl::if_c<
-                        (n_value == 0)
-                      , typename Sequence::first_type
-                      , typename Sequence::second_type
-                    >::type
+                    extension::struct_member<Sequence, N::value>::type
                 type;
             };
         };
diff --git a/include/boost/fusion/sequence/adapted/std_pair/Attic/std_pair_iterator.hpp b/include/boost/fusion/sequence/adapted/struct/struct_iterator.hpp
similarity index 51%
rename from include/boost/fusion/sequence/adapted/std_pair/Attic/std_pair_iterator.hpp
rename to include/boost/fusion/sequence/adapted/struct/struct_iterator.hpp
index 4aa2daa2..0684deaf 100644
--- a/include/boost/fusion/sequence/adapted/std_pair/Attic/std_pair_iterator.hpp
+++ b/include/boost/fusion/sequence/adapted/struct/struct_iterator.hpp
@@ -1,14 +1,17 @@
 /*=============================================================================
-    Copyright (c) 2001-2006 Joel de Guzman
+    Copyright (c) 2001-2007 Joel de Guzman
+    Copyright (c) 2005-2006 Dan Marsden
 
-    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    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_STD_PAIR_ITERATOR_09262005_0934)
-#define FUSION_STD_PAIR_ITERATOR_09262005_0934
+#if !defined(FUSION_STRUCT_ITERATOR_APRIL_2_2007_1008AM)
+#define FUSION_STRUCT_ITERATOR_APRIL_2_2007_1008AM
 
 #include <boost/fusion/iterator/iterator_facade.hpp>
 #include <boost/type_traits/is_const.hpp>
+#include <boost/type_traits/add_reference.hpp>
+#include <boost/type_traits/add_const.hpp>
 #include <boost/mpl/assert.hpp>
 #include <boost/mpl/identity.hpp>
 #include <boost/mpl/if.hpp>
@@ -18,69 +21,71 @@
 
 namespace boost { namespace fusion
 {
-    struct random_access_traversal_tag;
-
-    template <typename Pair_, int N_>
-    struct std_pair_iterator
-        : iterator_facade<std_pair_iterator<Pair_, N_>, random_access_traversal_tag>
+    namespace extension
     {
-        BOOST_MPL_ASSERT_RELATION(N_, >=, 0);
-        BOOST_MPL_ASSERT_RELATION(N_, <=, 2);
+        template <typename Struct, int N>
+        struct struct_member;
 
-        typedef mpl::int_<N_> index;
-        typedef Pair_ pair_type;
+        template <typename Struct>
+        struct struct_size;
 
-        std_pair_iterator(Pair_& pair)
-            : pair(pair) {}
-        Pair_& pair;
-
-        template <typename Iterator>
-        struct value_of;
-
-        template <typename Pair>
-        struct value_of<std_pair_iterator<Pair, 0> >
-            : mpl::identity<typename Pair::first_type> {};
-
-        template <typename Pair>
-        struct value_of<std_pair_iterator<Pair, 1> >
-            : mpl::identity<typename Pair::second_type> {};
-
-        template <typename Iterator>
-        struct deref;
-
-        template <typename Pair>
-        struct deref<std_pair_iterator<Pair, 0> >
+        template <typename Struct, int N>
+        struct struct_member<Struct const, N>
         {
             typedef typename
-                mpl::if_<
-                    is_const<Pair>
-                  , typename Pair::first_type const&
-                  , typename Pair::first_type&
-                >::type
+                add_const<typename struct_member<Struct, N>::type>::type
             type;
 
-            static type
-            call(std_pair_iterator<Pair, 0> const& iter)
+            static type&
+            call(Struct const& struct_)
             {
-                return iter.pair.first;
+                return struct_member<Struct, N>::call(
+                    const_cast<Struct&>(struct_));
             }
         };
 
-        template <typename Pair>
-        struct deref<std_pair_iterator<Pair, 1> >
+        template <typename Struct>
+        struct struct_size<Struct const>
+            : struct_size<Struct>
+        {};
+    }
+
+    struct random_access_traversal_tag;
+
+    template <typename Struct, int N_>
+    struct struct_iterator
+        : iterator_facade<struct_iterator<Struct, N_>, random_access_traversal_tag>
+    {
+        BOOST_MPL_ASSERT_RELATION(N_, >=, 0);
+        BOOST_MPL_ASSERT_RELATION(N_, <=, extension::struct_size<Struct>::value);
+
+        typedef mpl::int_<N_> index;
+        typedef Struct struct_type;
+
+        struct_iterator(Struct& struct_)
+            : struct_(struct_) {}
+        Struct& struct_;
+
+        template <typename Iterator>
+        struct value_of
+            : extension::struct_member<Struct, N_>
+        {
+        };
+
+        template <typename Iterator>
+        struct deref
         {
             typedef typename
-                mpl::if_<
-                    is_const<Pair>
-                  , typename Pair::second_type const&
-                  , typename Pair::second_type&
+                add_reference<
+                    typename extension::struct_member<Struct, N_>::type
                 >::type
             type;
 
             static type
-            call(std_pair_iterator<Pair, 1> const& iter)
+            call(Iterator const& iter)
             {
-                return iter.pair.second;
+                return extension::struct_member<Struct, N_>::
+                    call(iter.struct_);
             }
         };
 
@@ -88,13 +93,13 @@ namespace boost { namespace fusion
         struct advance
         {
             typedef typename Iterator::index index;
-            typedef typename Iterator::pair_type pair_type;
-            typedef std_pair_iterator<pair_type, index::value + N::value> type;
+            typedef typename Iterator::struct_type struct_type;
+            typedef struct_iterator<struct_type, index::value + N::value> type;
 
             static type
             call(Iterator const& iter)
             {
-                return type(iter.pair);
+                return type(iter.struct_);
             }
         };
 
@@ -110,7 +115,7 @@ namespace boost { namespace fusion
             typedef typename
                 mpl::minus<
                     typename I2::index, typename I1::index
-                >::type 
+                >::type
             type;
 
             static type