extent.hpp

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// SPDX-License-Identifier: BSL-1.0
// SPDX-FileCopyrightText: Copyright (C) 2019 Tobias Hienzsch
 
#ifndef TETL_TYPE_TRAITS_EXTENT_HPP
#define TETL_TYPE_TRAITS_EXTENT_HPP
 
#include <etl/_cstddef/size_t.hpp>
#include <etl/_type_traits/integral_constant.hpp>
 
namespace etl {
 
/// \brief If T is an array type, provides the member constant value equal to
/// the number of elements along the Nth dimension of the array, if N is in [0,
/// rank_v<T>). For any other type, or if T is an array of unknown bound along
/// its first dimension and N is 0, value is 0.
template <typename T, unsigned N = 0>
struct extent : integral_constant<size_t, 0> { };
 
template <typename T>
struct extent<T[], 0> : integral_constant<size_t, 0> { };
 
template <typename T, unsigned N>
struct extent<T[], N> : extent<T, N - 1> { };
 
template <typename T, size_t I>
struct extent<T[I], 0> : integral_constant<size_t, I> { };
 
template <typename T, size_t I, unsigned N>
struct extent<T[I], N> : extent<T, N - 1> { };
 
template <typename T, unsigned N = 0>
inline constexpr auto extent_v = static_cast<size_t>(extent<T, N>::value);
 
} // namespace etl
 
#endif // TETL_TYPE_TRAITS_EXTENT_HPP