ceph/src/boost/boost/gil/io/dynamic_io_new.hpp

   1 //
   2 // Copyright 2005-2007 Adobe Systems Incorporated
   3 //
   4 // Distributed under the Boost Software License, Version 1.0
   5 // See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt
   7 //
   8 #ifndef BOOST_GIL_IO_DYNAMIC_IO_NEW_HPP
   9 #define BOOST_GIL_IO_DYNAMIC_IO_NEW_HPP
  10
  11 #include <boost/gil/extension/dynamic_image/dynamic_image_all.hpp>
  12
  13 #include <boost/gil/detail/mp11.hpp>
  14 #include <boost/gil/io/error.hpp>
  15
  16 #include <type_traits>
  17
  18 namespace boost { namespace gil {
  19
  20 namespace detail {
  21
  22 template <long N>
  23 struct construct_matched_t
  24 {
  25     template <typename ...Images,typename Pred>
  26     static bool apply(any_image<Images...>& img, Pred pred)
  27     {
  28         if (pred.template apply<mp11::mp_at_c<any_image<Images...>, N-1>>())
  29         {
  30             using image_t = mp11::mp_at_c<any_image<Images...>, N-1>;
  31             image_t x;
  32             img = std::move(x);
  33             return true;
  34         }
  35         else
  36             return construct_matched_t<N-1>::apply(img, pred);
  37     }
  38 };
  39 template <>
  40 struct construct_matched_t<0>
  41 {
  42     template <typename ...Images,typename Pred>
  43     static bool apply(any_image<Images...>&,Pred) { return false; }
  44 };
  45
  46 // A function object that can be passed to apply_operation.
  47 // Given a predicate IsSupported taking a view type and returning an boolean integral coonstant,
  48 // calls the apply method of OpClass with the view if the given view IsSupported, or throws an exception otherwise
  49 template <typename IsSupported, typename OpClass>
  50 class dynamic_io_fnobj
  51 {
  52 private:
  53     OpClass* _op;
  54
  55     template <typename View>
  56     void apply(View const& view, std::true_type) { _op->apply(view); }
  57
  58     template <typename View, typename Info>
  59     void apply(View const& view, Info const & info, const std::true_type) { _op->apply(view, info); }
  60
  61     template <typename View>
  62     void apply(View const& /* view */, std::false_type)
  63     {
  64         io_error("dynamic_io: unsupported view type for the given file format");
  65     }
  66
  67     template <typename View, typename Info >
  68     void apply(View const& /* view */, Info const& /* info */, const std::false_type)
  69     {
  70         io_error("dynamic_io: unsupported view type for the given file format");
  71     }
  72
  73 public:
  74     dynamic_io_fnobj(OpClass* op) : _op(op) {}
  75
  76     using result_type = void;
  77
  78     template <typename View>
  79     void operator()(View const& view)
  80     {
  81         apply(view, typename IsSupported::template apply<View>::type());
  82     }
  83
  84     template< typename View, typename Info >
  85     void operator()(View const& view, Info const& info)
  86     {
  87         apply(view, info, typename IsSupported::template apply<View>::type());
  88     }
  89 };
  90
  91 } // namespace detail
  92
  93 /// \brief Within the any_image, constructs an image with the given dimensions
  94 ///        and a type that satisfies the given predicate
  95 template <typename ...Images,typename Pred>
  96 inline bool construct_matched(any_image<Images...>& img, Pred pred)
  97 {
  98     constexpr auto size = mp11::mp_size<any_image<Images...>>::value;
  99     return detail::construct_matched_t<size>::apply(img, pred);
 100 }
 101
 102 } }  // namespace boost::gil
 103
 104 #endif