1 /*=============================================================================
2     Copyright (c) 2001-2011 Joel de Guzman
3 
4     Distributed under the Boost Software License, Version 1.0. (See accompanying
5     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6 ==============================================================================*/
7 #if !defined(FUSION_CONVERT_ITERATOR_05062005_1218)
8 #define FUSION_CONVERT_ITERATOR_05062005_1218
9 
10 #include <boost/fusion/support/config.hpp>
11 #include <boost/fusion/support/is_iterator.hpp>
12 #include <boost/mpl/if.hpp>
13 #include <boost/mpl/bool.hpp>
14 
15 namespace boost { namespace fusion
16 {
17     template <typename Iterator>
18     struct mpl_iterator; // forward declaration
19 
20     //  Test T. If it is a fusion iterator, return a reference to it.
21     //  else, assume it is an mpl iterator.
22 
23     template <typename T>
24     struct convert_iterator
25     {
26         typedef typename
27             mpl::if_<
28                 is_fusion_iterator<T>
29               , T
30               , mpl_iterator<T>
31             >::type
32         type;
33 
34         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
35         static T const&
callboost::fusion::convert_iterator36         call(T const& x, mpl::true_)
37         {
38             return x;
39         }
40 
41         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
42         static mpl_iterator<T>
callboost::fusion::convert_iterator43         call(T const& /*x*/, mpl::false_)
44         {
45             return mpl_iterator<T>();
46         }
47 
48         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
49         static typename
50             mpl::if_<
51                 is_fusion_iterator<T>
52               , T const&
53               , mpl_iterator<T>
54             >::type
callboost::fusion::convert_iterator55         call(T const& x)
56         {
57             return call(x, is_fusion_iterator<T>());
58         }
59     };
60 }}
61 
62 #endif
63