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/* SPDX-License-Identifier: BSL-1.0 OR BSD-3-Clause */
#ifndef MPT_BASE_ARRAY_HPP
#define MPT_BASE_ARRAY_HPP
#include "mpt/base/detect.hpp"
#include "mpt/base/namespace.hpp"
#include <array>
#include <type_traits>
#include <cstddef>
namespace mpt {
inline namespace MPT_INLINE_NS {
template <typename T>
struct stdarray_extent : std::integral_constant<std::size_t, 0> { };
template <typename T, std::size_t N>
struct stdarray_extent<std::array<T, N>> : std::integral_constant<std::size_t, N> { };
template <typename T>
struct is_stdarray : std::false_type { };
template <typename T, std::size_t N>
struct is_stdarray<std::array<T, N>> : std::true_type { };
// mpt::extent is the same as std::extent,
// but also works for std::array,
// and asserts that the given type is actually an array type instead of returning 0.
// use as:
// mpt::extent<decltype(expr)>()
// mpt::extent<decltype(variable)>()
// mpt::extent<decltype(type)>()
// mpt::extent<type>()
template <typename T>
constexpr std::size_t extent() noexcept {
using Tarray = typename std::remove_cv<typename std::remove_reference<T>::type>::type;
static_assert(std::is_array<Tarray>::value || mpt::is_stdarray<Tarray>::value);
if constexpr (mpt::is_stdarray<Tarray>::value) {
return mpt::stdarray_extent<Tarray>();
} else {
return std::extent<Tarray>();
}
}
template <typename>
struct array_size;
template <typename T, std::size_t N>
struct array_size<std::array<T, N>> {
static constexpr std::size_t size = N;
};
template <typename T, std::size_t N>
struct array_size<T[N]> {
static constexpr std::size_t size = N;
};
template <typename T, std::size_t N, typename Tx>
constexpr std::array<T, N> init_array(const Tx & x) {
std::array<T, N> result{};
for (std::size_t i = 0; i < N; ++i) {
result[i] = x;
}
return result;
}
} // namespace MPT_INLINE_NS
} // namespace mpt
#endif // MPT_BASE_ARRAY_HPP
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