segmented_size, for calculating the size of any segmented data structure

[SVN r35945]

include/boost/fusion/sequence/intrinsic/ext_/size_s.hpp

@@ -0,0 +1,55 @@
+/*=============================================================================
+    Copyright (c) 2006 Eric Niebler
+
+    Use, modification and distribution is subject to 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_SIZE_S_08112006_1141)
+#define FUSION_SIZE_S_08112006_1141
+
+#include <boost/mpl/plus.hpp>
+#include <boost/mpl/size_t.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+#include <boost/fusion/algorithm/iteration/fold.hpp>
+#include <boost/fusion/support/ext_/is_segmented.hpp>
+#include <boost/fusion/sequence/intrinsic/ext_/segments.hpp>
+
+namespace boost { namespace fusion
+{
+    ///////////////////////////////////////////////////////////////////////////
+    // calculates the size of any segmented data structure.
+    template<typename Sequence, bool IsSegmented = traits::is_segmented<Sequence>::value>
+    struct segmented_size;
+
+    namespace detail
+    {
+        struct size_plus
+        {
+            template<typename Seq, typename State>
+            struct result
+              : mpl::plus<
+                    segmented_size<typename remove_reference<Seq>::type>
+                  , State
+                >
+            {};
+        };
+    }
+
+    ///////////////////////////////////////////////////////////////////////////
+    template<typename Sequence, bool IsSegmented>
+    struct segmented_size
+      : result_of::fold<
+            typename result_of::segments<Sequence>::type
+          , mpl::size_t<0>
+          , detail::size_plus
+        >::type
+    {};
+
+    template<typename Sequence>
+    struct segmented_size<Sequence, false>
+      : result_of::size<Sequence>
+    {};
+}}
+
+#endif