Boost C++ Libraries

boost/fusion/algorithm/transformation/push_front.hpp

/*=============================================================================
    Copyright (c) 2001-2011 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_PUSH_FRONT_07162005_0749)
#define FUSION_PUSH_FRONT_07162005_0749

#include <boost/fusion/support/detail/as_fusion_element.hpp>
#include <boost/fusion/view/joint_view/joint_view.hpp>
#include <boost/fusion/view/single_view/single_view.hpp>
#include <boost/fusion/support/is_sequence.hpp>
#include <boost/utility/enable_if.hpp>

namespace boost { namespace fusion
{
    namespace result_of
    {
        template <typename Sequence, typename T>
        struct push_front
        {
            typedef fusion::single_view<typename detail::as_fusion_element<T>::type> single_view;
            typedef joint_view<single_view const, Sequence> type;
        };
    }

    template <typename Sequence, typename T>
    inline 
    typename
        lazy_enable_if<
            traits::is_sequence<Sequence>
          , result_of::push_front<Sequence const, T>
        >::type
    push_front(Sequence const& seq, T const& x)
    {
        typedef typename result_of::push_front<Sequence const, T> push_front;
        typedef typename push_front::single_view single_view; 
        typedef typename push_front::type result; 
        single_view x_(x);
        return result(x_, seq);
    }
}}

#endif