owning_view.hpp

// SPDX-FileCopyrightText: Intel Corporation
//
// SPDX-License-Identifier: BSD-3-Clause
 
#pragma once
 
#include <dr/detail/ranges_shim.hpp>
 
namespace dr {
 
namespace __detail {
 
// TODO: this `owning_view` is needed because range-v3 does not have an
//       `owning_view`.  Ideally we would submit a PR to range-v3 /or
//       switch to solely using libstdc++13.
 
template <rng::range R>
class owning_view : public rng::view_interface<owning_view<R>> {
public:
  owning_view(R &&range) : range_(std::move(range)) {}
 
  owning_view()
    requires std::default_initializable<R>
  = default;
  owning_view(owning_view &&other) = default;
  owning_view(const owning_view &other) = default;
 
  owning_view &operator=(owning_view &&other) = default;
  owning_view &operator=(const owning_view &other) = default;
 
  auto size() const
    requires(rng::sized_range<R>)
  {
    return rng::size(range_);
  }
 
  auto empty() const
    requires(rng::sized_range<R>)
  {
    return size() == 0;
  }
 
  auto begin() { return rng::begin(range_); }
 
  auto begin() const
    requires(rng::range<const R>)
  {
    return rng::begin(range_);
  }
 
  auto end() { return rng::end(range_); }
 
  auto end() const
    requires(rng::range<const R>)
  {
    return rng::end(range_);
  }
 
  decltype(auto) base() { return range_; }
 
  decltype(auto) base() const { return range_; }
 
private:
  R range_;
};
 
} // namespace __detail
 
} // namespace dr