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44 lines
1.3 KiB
C++
44 lines
1.3 KiB
C++
#pragma once
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#include <utility>
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#include <type_traits>
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#include <array>
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/** \brief Produces std::array of specified size, containing copies of provided object.
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* Copy is performed N-1 times, and the last element is being moved.
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* This helper allows to initialize std::array in place.
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*/
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namespace ext
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{
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namespace detail
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{
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template<std::size_t size, typename T, std::size_t... indexes>
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constexpr auto make_array_n_impl(T && value, std::index_sequence<indexes...>)
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{
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/// Comma is used to make N-1 copies of value
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return std::array<std::decay_t<T>, size>{ (static_cast<void>(indexes), value)..., std::forward<T>(value) };
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}
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}
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template<typename T>
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constexpr auto make_array_n(std::integral_constant<std::size_t, 0>, T &&)
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{
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return std::array<std::decay_t<T>, 0>{};
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}
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template<std::size_t size, typename T>
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constexpr auto make_array_n(std::integral_constant<std::size_t, size>, T && value)
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{
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return detail::make_array_n_impl<size>(std::forward<T>(value), std::make_index_sequence<size - 1>{});
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}
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template<std::size_t size, typename T>
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constexpr auto make_array_n(T && value)
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{
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return make_array_n(std::integral_constant<std::size_t, size>{}, std::forward<T>(value));
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}
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}
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