count.hpp

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// SPDX-License-Identifier: BSL-1.0
// SPDX-FileCopyrightText: Copyright (C) 2024 Tobias Hienzsch
 
#ifndef TETL_MPL_COUNT_HPP
#define TETL_MPL_COUNT_HPP
 
#include <etl/_cstddef/size_t.hpp>
#include <etl/_mpl/list.hpp>
#include <etl/_type_traits/integral_constant.hpp>
#include <etl/_type_traits/is_same.hpp>
 
namespace etl::mpl {
 
/// \ingroup mpl
/// @{
 
template <typename Needle, typename Haystack>
struct count;
 
template <typename Needle, typename... Ts>
struct count<Needle, list<Ts...>> : etl::integral_constant<etl::size_t, (etl::is_same_v<Needle, Ts> + ... + 0)> { };
 
template <typename Needle, typename Haystack>
inline constexpr auto count_v = count<Needle, Haystack>::value;
 
/// @}
 
} // namespace etl::mpl
 
#endif // TETL_MPL_COUNT_HPP