#include <iostream>
#include <boost/gil/gil_all.hpp>
using namespace boost;
using namespace gil;

//
// Do-nothing dereference adaptor
//
template <typename View>
struct deref_fn {
    BOOST_STATIC_CONSTANT(bool, is_mutable=false);
    typedef deref_fn<typename View::const_t> const_t;
    typedef typename View::value_type value_type;
    typedef typename View::reference reference;
    typedef typename View::point_t argument_type;
    typedef reference result_type;

    deref_fn() {;}
    deref_fn(const View& v) : mView(v) { ; }
    result_type operator()(const argument_type& p) const {
        return mView(p);
    }

    View mView;
};

typedef rgb8_planar_image_t image_t;
typedef image_t::view_t view_t;
typedef deref_fn<view_t> fn_t; 
typedef virtual_2d_locator<fn_t, false> loc_t;
typedef image_view<loc_t> virt_view_t;
typedef kth_channel_view_type<0, virt_view_t>::type chan0_view_t;

int main(int argc, char **argv) {
    image_t img(4,4,rgb8_pixel_t(1,2,3),0);
    view_t v(view(img));

    fn_t fn(v);
    loc_t loc(view_t::point_t(0,0), view_t::point_t(1,1), fn);
    virt_view_t virtView(v.dimensions(), loc);

    //
    // Here detail::kth_channel_deref_fn<K,SrcP> is instantiated with
    // SrcP = 'planar_pixel_reference<bits8&, rgb_t>'. The  
    // kth_channel_deref_fn then declares its result_type (and thereby 
    // the chan0_view_t:reference) to be a
    // 'pixel<bits8&, gray_layout_t>&'
    //
    chan0_view_t chan0View(kth_channel_view<0,virt_view_t>(virtView));

    assert((is_same<chan0_view_t::reference, 
                    pixel<bits8&, gray_layout_t>& >::value));

    //
    // This will typically cause a bus error because the result_type
    // of the deref adaptor is a 'pixel<bits8&, gray_layout_t>&'
    // which gets initialized in the deref function by a 
    // 'pixel<bits8, gray_layout_t>&'
    //
    assert(chan0View(0,0) == gray8_pixel_t(1));
    return 0;
}