#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>
#endif
namespace tcg
{
template <typename X, typename Y>
struct type_match {
enum { value = false };
};
template <typename X>
struct type_match<X, X> {
enum { value = true };
};
//------------------------------------------------------------------------
template <typename X, typename Y>
struct type_mismatch {
enum { value = true };
};
template <typename X>
struct type_mismatch<X, X> {
enum { value = false };
};
//========================================================================
template <typename T, typename B>
struct enable_if_exists {
typedef B type;
};
//========================================================================
template <bool, typename T = void>
struct enable_if {
};
template <typename T>
struct enable_if<true, T> {
typedef T type;
};
//========================================================================
template <bool, typename T = void>
struct disable_if {
typedef T type;
};
template <typename T>
struct disable_if<true, T> {
};
//========================================================================
template <bool, typename TrueT, typename FalseT = void>
struct choose_if;
template <typename TrueT, typename FalseT>
struct choose_if<true, TrueT, FalseT> {
typedef TrueT type;
};
template <typename TrueT, typename FalseT>
struct choose_if<false, TrueT, FalseT> {
typedef FalseT type;
};
//========================================================================
template <typename T, typename MatchT, typename NotMatchedT = void>
struct choose_if_match {
typedef NotMatchedT type;
};
template <typename MatchT, typename NotMatchedT>
struct choose_if_match<MatchT, MatchT, NotMatchedT> {
typedef MatchT type;
};
} // namespace tcg
#endif // TCG_SFINAE_H