Count.hpp

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//
//  CeresEngine - A game development framework
//
//  Created by Rogiel Sulzbach.
//  Copyright (c) 2018-2022 Rogiel Sulzbach. All rights reserved.
//
 
#pragma once
 
#include "TypeList.hpp"
 
#include <type_traits>
 
namespace CeresEngine::MPL {
 
    template<typename T, typename TTypeList> struct CountHelper : std::integral_constant<std::size_t, 0> {};
 
    template<typename T, typename TTypeList> inline constexpr size_t Count = CountHelper<T, TTypeList>::value;
 
    template<typename T, typename T0, typename... Ts>
    struct CountHelper<T, TypeList<T0, Ts...>> : std::integral_constant<std::size_t, (std::is_same_v<T, T0> ? 1 : 0) + Count<T, TypeList<Ts...>>> {};
 
    template<typename T, typename TTypeList> inline constexpr bool Contains = Count<T, TTypeList> > 0;
 
} // namespace CeresEngine::MPL