text: //
  // 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_CONCEPTS_PIXEL_DEREFERENCE_HPP
  #define BOOST_GIL_CONCEPTS_PIXEL_DEREFERENCE_HPP
  
  #include <boost/gil/concepts/basic.hpp>
  #include <boost/gil/concepts/concept_check.hpp>
  #include <boost/gil/concepts/fwd.hpp>
  #include <boost/gil/concepts/pixel.hpp>
  #include <boost/gil/concepts/detail/type_traits.hpp>
  
  #include <boost/concept_check.hpp>
  
  #include <cstddef>
  #include <type_traits>
  
  #if defined(BOOST_CLANG)
  #pragma clang diagnostic push
  #pragma clang diagnostic ignored "-Wunused-local-typedefs"
  #endif
  
  #if defined(BOOST_GCC) && (BOOST_GCC >= 40900)
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wunused-local-typedefs"
  #endif
  
  namespace boost { namespace gil {
  
  /// \ingroup PixelDereferenceAdaptorConcept
  /// \brief Represents a unary function object that can be invoked upon dereferencing a pixel iterator.
  ///
  /// This can perform an arbitrary computation, such as color conversion or table lookup.
  /// \code
  /// concept PixelDereferenceAdaptorConcept<boost::UnaryFunctionConcept D>
  ///     : DefaultConstructibleConcept<D>, CopyConstructibleConcept<D>, AssignableConcept<D>
  /// {
  ///     typename const_t; where PixelDereferenceAdaptorConcept<const_t>;
  ///     typename value_type; where PixelValueConcept<value_type>;
  ///     typename reference;         // may be mutable
  ///     typename const_reference;   // must not be mutable
  ///     static const bool D::is_mutable;
  ///
  ///     where Convertible<value_type,result_type>;
  /// };
  /// \endcode
  template <typename D>
  struct PixelDereferenceAdaptorConcept
  {
      void constraints()
      {
          gil_function_requires
          <
              boost::UnaryFunctionConcept
              <
                  D,
                  typename detail::remove_const_and_reference<typename D::result_type>::type,
                  typename D::argument_type
              >
          >();
          gil_function_requires<boost::DefaultConstructibleConcept<D>>();
          gil_function_requires<boost::CopyConstructibleConcept<D>>();
          gil_function_requires<boost::AssignableConcept<D>>();
  
          gil_function_requires<PixelConcept
              <
                  typename detail::remove_const_and_reference<typename D::result_type>::type
              >>();
  
          using const_t = typename D::const_t;
          gil_function_requires<PixelDereferenceAdaptorConcept<const_t>>();
  
          using value_type = typename D::value_type;
          gil_function_requires<PixelValueConcept<value_type>>();
  
          // TODO: Should this be concept-checked after "if you remove const and reference"? --mloskot
          using reference = typename D::reference; // == PixelConcept (if you remove const and reference)
          using const_reference = typename D::const_reference; // == PixelConcept (if you remove const and reference)
  
          bool const is_mutable = D::is_mutable;
          ignore_unused_variable_warning(is_mutable);
      }
      D d;
  };
  
  template <typename P>
  struct PixelDereferenceAdaptorArchetype
  {
      using argument_type = P;
      using result_type = P;
      using const_t = PixelDereferenceAdaptorArchetype;
      using value_type = typename std::remove_reference<P>::type;
      using reference = typename std::add_lvalue_reference<P>::type;
      using const_reference = reference;
  
      static const bool is_mutable = false;
      P operator()(P) const { throw; }
  };
  
  }} // namespace boost::gil
  
  #if defined(BOOST_CLANG)
  #pragma clang diagnostic pop
  #endif
  
  #if defined(BOOST_GCC) && (BOOST_GCC >= 40900)
  #pragma GCC diagnostic pop
  #endif
  
  #endif
  