#pragma once

#ifndef TCG_SFINAE_H

#define TCG_SFINAE_H

/*!

  \file     sfinae.h

  \brief    Contains template metafunctions that can be used to enable or

            disable template class members.

  \details  SFINAE (Substitution Failure Is Not An Error) is a C++ \a feature

            that allows the compiler to silently discard failures in template

            function instantiations during function overload resolution.

*/

#if defined(__APPLE_CC__)

#include <type_traits></type_traits>

#endif

namespace tcg {

template <typename typename="" x,="" y=""></typename>

struct type_match {

  enum { value = false };

};

template <typename x=""></typename>

struct type_match<x, x=""> {</x,>

  enum { value = true };

};

//------------------------------------------------------------------------

template <typename typename="" x,="" y=""></typename>

struct type_mismatch {

  enum { value = true };

};

template <typename x=""></typename>

struct type_mismatch<x, x=""> {</x,>

  enum { value = false };

};

//========================================================================

template <typename b="" t,="" typename=""></typename>

struct enable_if_exists {

  typedef B type;

};

//========================================================================

template <bool, t="void" typename=""></bool,>

struct enable_if {};

template <typename t=""></typename>

struct enable_if<true, t=""> {</true,>

  typedef T type;

};

//========================================================================

template <bool, t="void" typename=""></bool,>

struct disable_if {

  typedef T type;

};

template <typename t=""></typename>

struct disable_if<true, t=""> {};</true,>

//========================================================================

template <bool, falset="void" truet,="" typename=""></bool,>

struct choose_if;

template <typename falset="" truet,="" typename=""></typename>

struct choose_if<true, falset="" truet,=""> {</true,>

  typedef TrueT type;

};

template <typename falset="" truet,="" typename=""></typename>

struct choose_if<false, falset="" truet,=""> {</false,>

  typedef FalseT type;

};

//========================================================================

template <typename matcht,="" notmatchedt="void" t,="" typename=""></typename>

struct choose_if_match {

  typedef NotMatchedT type;

};

template <typename matcht,="" notmatchedt="" typename=""></typename>

struct choose_if_match<matcht, matcht,="" notmatchedt=""> {</matcht,>

  typedef MatchT type;

};

}  // namespace tcg

#endif  // TCG_SFINAE_H