as_const_view.hpp

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//
// Created by yonggyulee on 1/15/24.
//
 
#ifndef VCCC_RANGES_VIEWS_AS_CONST_VIEW_HPP
#define VCCC_RANGES_VIEWS_AS_CONST_VIEW_HPP
 
#include <utility>
 
#include "vccc/__concepts/copy_constructible.hpp"
#include "vccc/__ranges/cbegin.hpp"
#include "vccc/__ranges/simple_view.hpp"
#include "vccc/__ranges/enable_borrowed_range.hpp"
#include "vccc/__ranges/input_range.hpp"
#include "vccc/__ranges/range.hpp"
#include "vccc/__ranges/view_interface.hpp"
#include "vccc/__ranges/view.hpp"
 
namespace vccc {
namespace ranges {
 
 
template<typename V>
class as_const_view : public view_interface<as_const_view<V>> {
 public:
  static_assert(view<V>::value, "Constraints not satisfied");
  static_assert(input_range<V>::value, "Constraints not satisfied");
 
  as_const_view() = default;
 
  constexpr explicit as_const_view(V base)
      : base_(std::move(base)) {}
 
  template<typename V2 = V, std::enable_if_t<copy_constructible<V2>::value, int> = 0>
  constexpr V base() const& {
    return base_;
  }
 
  constexpr V base() && {
    return std::move(base_);
  }
 
  template<typename V2 = V, std::enable_if_t<simple_view<V2>::value == false, int> = 0>
  constexpr auto begin() {
    return vccc::ranges::cbegin(base_);
  }
 
  template<typename V2 = const V, std::enable_if_t<range<V2>::value, int> = 0>
  constexpr auto begin() const {
    return vccc::ranges::cbegin(base_);
  }
 
  template<typename V2 = V, std::enable_if_t<simple_view<V2>::value == false, int> = 0>
  constexpr auto end() {
    return vccc::ranges::cend(base_);
  }
 
  template<typename V2 = const V, std::enable_if_t<range<V2>::value, int> = 0>
  constexpr auto end() const {
    return vccc::ranges::cend(base_);
  }
 
  template<typename V2 = V, std::enable_if_t<sized_range<V2>::value, int> = 0>
  constexpr auto size() {
    return vccc::ranges::size(base_);
  }
 
  template<typename V2 = const V, std::enable_if_t<sized_range<V2>::value, int> = 0>
  constexpr auto size() const {
    return vccc::ranges::size(base_);
  }
 
 private:
  V base_;
};
 
#if __cplusplus >= 201703L
 
template<typename R>
as_const_view(R&&) -> as_const_view<views::all_t<R>>;
 
#endif
 
template<typename T>
struct enable_borrowed_range<as_const_view<T>> : enable_borrowed_range<T> {};
 
 
} // namespace ranges
} // namespace vccc
 
#endif // VCCC_RANGES_VIEWS_AS_CONST_VIEW_HPP