44 lines
1.4 KiB
C++
44 lines
1.4 KiB
C++
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// 2020/08/28 - Created by netcan: https://github.com/netcan
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#pragma once
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#include <cstddef>
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#include <tuple>
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namespace tf {
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namespace dsl {
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namespace detail {
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// get tuple element index by f, if not exists then index >= tuple_size
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template <typename TUP, template <typename> class F, typename = void>
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struct TupleElementByF {
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constexpr static size_t Index = 0;
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};
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template <template <typename> class F, typename H, typename... Ts>
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struct TupleElementByF<std::tuple<H, Ts...>, F, std::enable_if_t<F<H>::value>> {
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constexpr static size_t Index = 0;
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};
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template <template <typename> class F, typename H, typename... Ts>
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struct TupleElementByF<std::tuple<H, Ts...>, F,
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std::enable_if_t<!F<H>::value>> {
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constexpr static size_t Index =
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1 + TupleElementByF<std::tuple<Ts...>, F>::Index;
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};
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template <typename T, typename TUP, size_t... Is>
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constexpr inline T AggregationByTupImpl(TUP &&tup, std::index_sequence<Is...>) {
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return T{std::get<Is>(tup)...};
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}
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} // namespace detail
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template <typename TUP, template <typename> class F>
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constexpr size_t TupleElementByF_v = detail::TupleElementByF<TUP, F>::Index;
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template <typename T, typename TUP>
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constexpr inline T AggregationByTup(TUP &&tup) {
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return detail::AggregationByTupImpl<T>(
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std::forward<TUP>(tup),
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std::make_index_sequence<std::tuple_size<std::decay_t<TUP>>::size>{});
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}
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} // namespace dsl
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} // namespace tf
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