dynamic_io_new.hpp

//
// Copyright 2005-2007 Adobe Systems Incorporated
//
// 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
//
#ifndef BOOST_GIL_IO_DYNAMIC_IO_NEW_HPP
#define BOOST_GIL_IO_DYNAMIC_IO_NEW_HPP

#include <boost/gil/extension/dynamic_image/dynamic_image_all.hpp>

#include <boost/gil/io/error.hpp>

#include <boost/mpl/at.hpp>
#include <boost/mpl/size.hpp>

namespace boost { namespace gil {

namespace detail {

template <long N>
struct construct_matched_t {
    template <typename Images,typename Pred>
    static bool apply(any_image<Images>& im,Pred pred) {
        if (pred.template apply<typename mpl::at_c<Images,N-1>::type>()) {
            typename mpl::at_c<Images,N-1>::type x;
            im = std::move(x);
            return true;
        } else return construct_matched_t<N-1>::apply(im,pred);
    }
};
template <>
struct construct_matched_t<0> {
    template <typename Images,typename Pred>
    static bool apply(any_image<Images>&,Pred) {return false;}
};

// A function object that can be passed to apply_operation.
// Given a predicate IsSupported taking a view type and returning an MPL boolean,
// calls the apply method of OpClass with the view if the given view IsSupported, or throws an exception otherwise
template <typename IsSupported, typename OpClass>
class dynamic_io_fnobj {
    OpClass* _op;

    template <typename View>
    void apply(const View& view,mpl::true_ ) {_op->apply(view);}

    template <typename View, typename Info >
    void apply( const View& view
              , const Info& info
              , const mpl::true_
              )
    {
        _op->apply( view, info );
    }

    template <typename View>
    void apply(const View& /* view */ ,mpl::false_) {io_error("dynamic_io: unsupported view type for the given file format");}

    template <typename View, typename Info >
    void apply( const View& /* view */
              , const Info& /* info */
              , const mpl::false_
              )
    {
        io_error( "dynamic_io: unsupported view type for the given file format" );
    }

public:
    dynamic_io_fnobj(OpClass* op) : _op(op) {}

    using result_type = void;

    template <typename View>
    void operator()(const View& view) {apply(view,typename IsSupported::template apply<View>::type());}

    template< typename View, typename Info >
    void operator()(const View& view, const Info& info )
    {
        apply( view
             , info
             , typename IsSupported::template apply< View >::type()
             );
    }

};

} // namespace detail

template <typename Images,typename Pred>
inline bool construct_matched(any_image<Images>& im,Pred pred) {
    return detail::construct_matched_t<mpl::size<Images>::value>::apply(im,pred);
}

} }  // namespace boost::gil

#endif