tuplevector.hh

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// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
// SPDX-FileCopyrightInfo: Copyright © DUNE Project contributors, see file LICENSE.md in module root
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception
#ifndef DUNE_COMMON_TUPLEVECTOR_HH
#define DUNE_COMMON_TUPLEVECTOR_HH

#include <tuple>
#include <utility>

#include <dune/common/indices.hh>
#include <dune/common/typetraits.hh>
#include <dune/common/std/type_traits.hh>



namespace Dune
{



template<class... T>
class TupleVector : public std::tuple<T...>
{
  using Base = std::tuple<T...>;

public:

  template<class... TT,
    class = std::void_t<decltype(Base(std::declval<TT&&>()...))>>
  constexpr TupleVector(TT&&... tt) :
    Base(std::forward<TT>(tt)...)
  {}

  constexpr TupleVector()
  {}

  template<std::size_t i,
    std::enable_if_t<(i < sizeof...(T)), int> = 0>
  constexpr decltype(auto) operator[](const Dune::index_constant<i>&) const
  {
    return std::get<i>(*this);
  }

  template<std::size_t i,
    std::enable_if_t<(i < sizeof...(T)), int> = 0>
  constexpr decltype(auto) operator[](const Dune::index_constant<i>&)
  {
    return std::get<i>(*this);
  }

  static constexpr std::size_t size()
  {
    return std::tuple_size<Base>::value;
  }
};


template<class... T>
TupleVector(T...) -> TupleVector<T...>;

template<class T1, class T2>
TupleVector(std::pair<T1, T2>) -> TupleVector<T1, T2>;

template<class... T>
TupleVector(std::tuple<T...>) -> TupleVector<T...>;

template <class Alloc, class... T>
TupleVector(std::allocator_arg_t, Alloc, T...) -> TupleVector<T...>;

template<class Alloc, class T1, class T2>
TupleVector(std::allocator_arg_t, Alloc, std::pair<T1, T2>) -> TupleVector<T1, T2>;

template<class Alloc, class... T>
TupleVector(std::allocator_arg_t, Alloc, std::tuple<T...>) -> TupleVector<T...>;



template<class... T>
constexpr auto makeTupleVector(T&&... t)
{
  // The std::decay_t<T> is is a slight simplification,
  // because std::reference_wrapper needs special care.
  return TupleVector<std::decay_t<T>...>(std::forward<T>(t)...);
}



}  // namespace Dune

namespace std
{
  template <size_t i, typename... Args>
  struct tuple_element<i,Dune::TupleVector<Args...> >
  {
    using type = typename std::tuple_element<i, std::tuple<Args...> >::type;
  };

  template <typename... Args>
  struct tuple_size<Dune::TupleVector<Args...> >
    : std::integral_constant<std::size_t, sizeof...(Args)>
  {};
}

#endif // DUNE_COMMON_TUPLEVECTOR_HH