tuple_utils.h

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/*  Copyright (c) SILVERCODERS Ltd, http://silvercoders.com                                                                                  */
/*  Project homepage: https://github.com/docwire/docwire                                                                                     */
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/*  SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-DocWire-Commercial                                                                  */
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#ifndef DOCWIRE_TUPLE_UTILS_H
#define DOCWIRE_TUPLE_UTILS_H
 
#include <tuple>
 
namespace docwire::tuple_utils
{
 
template <std::size_t Start, std::size_t Length, typename... Ts>
auto subrange(const std::tuple<Ts...>& tuple) {
    if constexpr (Length == 0) {
      return std::tuple<>();
    } else {
      static_assert(Start < sizeof...(Ts), "Start index out of range");
      static_assert(Start + Length <= sizeof...(Ts), "Length out of range");
      return std::tuple_cat(std::make_tuple(std::get<Start>(tuple)), subrange<Start + 1, Length - 1>(tuple));
    }
}
 
template <std::size_t Start, std::size_t Length, typename T>
using subrange_t = decltype(subrange<Start, Length>(std::declval<T>()));
 
template <typename T>
auto remove_first(T&& tuple) {
  static_assert(std::tuple_size_v<T> > 0, "Cannot remove the first element of an empty tuple.");
  return subrange<1, std::tuple_size_v<T> - 1>(tuple);
}
 
template <typename T>
using remove_first_t = decltype(remove_first(std::declval<T>()));
 
template <typename T>
auto remove_last(T&& tuple) {
  static_assert(std::tuple_size_v<T> > 0, "Cannot remove the last element of an empty tuple.");
  return subrange<0, std::tuple_size_v<T> - 1>(tuple);
}
 
template <typename T>
using remove_last_t = decltype(remove_last(std::declval<T>()));
 
template <typename T>
auto first_element(T&& tuple) {
  static_assert(std::tuple_size_v<T> > 0, "Cannot get the first element of an empty tuple.");
  return std::get<0>(tuple);
}
 
template <typename T>
using first_element_t = decltype(first_element(std::declval<T>()));
 
template <typename T>
auto last_element(T&& tuple) {
  static_assert(std::tuple_size_v<T> > 0, "Cannot get the last element of an empty tuple.");
  return std::get<std::tuple_size_v<T> - 1>(tuple);
}
 
template <typename T>
using last_element_t = decltype(last_element(std::declval<T>()));
 
} // namespace docwire::tuple_utils
 
#endif //DOCWIRE_TUPLE_UTILS_H