introduces deduce metafunctions

[SVN r36811]

include/boost/fusion/support/deduce.hpp

@@ -0,0 +1,87 @@
+/*=============================================================================
+    Copyright (c) 2007 Tobias Schwinger
+  
+    Use modification and distribution are 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(BOOST_FUSION_SUPPORT_DEDUCE_HPP_INCLUDED)
+#define BOOST_FUSION_SUPPORT_DEDUCE_HPP_INCLUDED
+
+#include <boost/ref.hpp>
+
+namespace boost { namespace fusion { namespace traits
+{
+    template <typename T> struct deduce;
+
+    //----- ---- --- -- - -  -   -
+
+    // Non-references pass unchanged
+
+    template <typename T>
+    struct deduce
+    {
+        typedef T type; 
+    };
+
+    // Keep references on mutable LValues
+
+    template <typename T>
+    struct deduce<T &>
+    {
+        typedef T & type;
+    };
+
+    template <typename T>
+    struct deduce<T volatile&>
+    {
+        typedef T volatile& type;
+    };
+
+    // Store away potential RValues
+
+    template <typename T>
+    struct deduce<T const&>
+    {
+        typedef T type;
+    };
+
+    template <typename T>
+    struct deduce<T const volatile&>
+    {
+        typedef T type;
+    };
+
+    // Unwrap Boost.RefS (referencee cv is deduced)
+
+    template <typename T>
+    struct deduce<reference_wrapper<T> & >
+    {
+        typedef T& type;
+    };
+
+    template <typename T>
+    struct deduce<reference_wrapper<T> const & >
+    {
+        typedef T& type;
+    };
+
+    // Keep references on arrays, even if const
+
+    template <typename T, int N>
+    struct deduce<const T(&)[N]>
+    {
+        typedef const T(&type)[N];
+    };
+
+    template <typename T, int N>
+    struct deduce<const volatile T(&)[N]>
+    {
+        typedef const volatile T(&type)[N];
+    };
+
+}}}
+
+#endif
+

include/boost/fusion/support/deduce_sequence.hpp

@@ -0,0 +1,43 @@
+/*=============================================================================
+    Copyright (c) 2007 Tobias Schwinger
+  
+    Use modification and distribution are 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(BOOST_FUSION_SUPPORT_DEDUCE_SEQUENCE_HPP_INCLUDED)
+#define BOOST_FUSION_SUPPORT_DEDUCE_SEQUENCE_HPP_INCLUDED
+
+#include <boost/fusion/support/deduce.hpp>
+#include <boost/fusion/sequence/conversion/as_vector.hpp>
+#include <boost/fusion/sequence/view/transform_view.hpp>
+
+namespace boost { namespace fusion { namespace traits
+{
+
+    template <class Sequence> struct deduce_sequence;
+
+    //----- ---- --- -- - -  -   -
+
+    namespace detail
+    {
+        struct deducer
+        {
+            template <typename T>
+            struct result
+                : fusion::traits::deduce<T>
+            { };
+        };
+    }
+
+    template <class Sequence>
+    struct deduce_sequence
+        : result_of::as_vector<
+            fusion::transform_view<Sequence, detail::deducer> >
+    { };
+
+}}}
+
+#endif
+