empty_view.hpp

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//
// Created by yonggyulee on 2024/01/02.
//
 
#ifndef VCCC_RANGES_VIEWS_EMPTY_VIEW_HPP
#define VCCC_RANGES_VIEWS_EMPTY_VIEW_HPP
 
#include <cstddef>
#include <type_traits>
 
#include "vccc/__core/inline_or_static.hpp"
#include "vccc/__ranges/enable_borrowed_range.hpp"
#include "vccc/__ranges/view_interface.hpp"
 
namespace vccc {
namespace ranges {
 
 
template<typename T>
class empty_view : public ranges::view_interface<empty_view<T>> {
 public:
  static_assert(std::is_object<T>::value, "Constraints not satisfied");
 
  static constexpr T* begin() noexcept { return nullptr; }
 
  static constexpr T* end() noexcept { return nullptr; }
 
  static constexpr T* data() noexcept { return nullptr; }
 
  static constexpr std::size_t size() noexcept { return 0; }
 
  static constexpr bool empty() noexcept { return true; }
};
 
template<typename T>
struct enable_borrowed_range<empty_view<T>> : std::true_type {};
 
namespace views {
 
template<typename T>
VCCC_INLINE_OR_STATIC constexpr empty_view<T> empty{};
 
} // namespace views
 
 
} // namespace ranges
} // namespace vccc
 
#endif // VCCC_RANGES_VIEWS_EMPTY_VIEW_HPP