[英]tuple of vectors from std::tuple
我正在嘗試從 std::tuple (原因: https://en.wikipedia.org/wiki/AoS_and_SoA )創建一個向量元組,並提出了以下代碼。
誰能想到一個更優雅、更簡潔的解決方案? PS:我堅持使用 C++14 編譯器......
template<std::size_t N, class T, template<class> class Allocator>
struct tuple_of_vectors {};
template<class T, template<class> class Allocator>
struct tuple_of_vectors<1, T, Allocator>
{
using type = std::tuple
<
std::vector
<
typename std::tuple_element<0, T>::type
, Allocator<typename std::tuple_element<0, T>::type>
>
>;
};
template<class T, template<class> class Allocator>
struct tuple_of_vectors<2, T, Allocator>
{
using type = std::tuple
<
std::vector
<
typename std::tuple_element<0, T>::type
, Allocator<typename std::tuple_element<0, T>::type>
>,
std::vector
<
typename std::tuple_element<1, T>::type
, Allocator<typename std::tuple_element<1, T>::type>
>
>;
};
// and so on...
template<class T, template<class> class Allocator>
class series
{
public:
using tov_type = typename tuple_of_vectors
<std::tuple_size<T>{}, T, Allocator>::type;
tov_type tov_;
};
您可以使用 C++14 std::index_sequence
提取tuple
的元素。
#include <tuple>
#include <vector>
#include <utility>
template<class IndexSeq, class Tuple, template<class> class Alloc>
struct tuple_of_vectors;
template<class Tuple, template<class> class Alloc, std::size_t... Is>
struct tuple_of_vectors<std::index_sequence<Is...>, Tuple, Alloc> {
using type = std::tuple<
std::vector<std::tuple_element_t<Is, Tuple>,
Alloc<std::tuple_element_t<Is, Tuple>>>...
>;
};
template<class Tuple, template<class> class Alloc>
class series {
public:
using tov_type = typename tuple_of_vectors<
std::make_index_sequence<std::tuple_size<Tuple>::value>, Tuple, Alloc>::type;
tov_type tov_;
};
Class 模板專業化和模式匹配有助於減少代碼大小。 我在下面包含了一個static_assert
測試:
#include <tuple>
#include <vector>
#include <type_traits>
template <typename>
struct tuple_of_vectors;
template <typename... Ts>
struct tuple_of_vectors<std::tuple<Ts...>> {
using type = std::tuple<std::vector<Ts>...>;
};
using t = typename tuple_of_vectors<std::tuple<int,double,float*>>::type;
static_assert(std::is_same<t,std::tuple<std::vector<int>,std::vector<double>,std::vector<float*>>>::value,"");
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