convertible_through_base.hpp

Go to the documentation of this file.

/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

 
#ifndef CONVERTIBLE_THROUGH_BASE_HPP
#define CONVERTIBLE_THROUGH_BASE_HPP

template <typename T>
concept ConvertibleThroughBase = requires(T const a) {
  typename T::BaseType;
  { a.base() } noexcept -> std::convertible_to<int64_t>;
};

template <typename T, typename TTo>
concept ConvertibleThroughBaseOrTo = std::is_convertible_v<T, TTo> || ConvertibleThroughBase<T>;

template <typename Container, typename Index>
class TypedIndexContainer : public Container {
public:
  Container::reference at(const Index &pos) { return this->Container::at(pos.base()); }
 
  Container::const_reference at(const Index &pos) const { return this->Container::at(pos.base()); }
 
  Container::reference operator[](const Index &pos) { return this->Container::operator[](pos.base()); }
 
  Container::const_reference operator[](const Index &pos) const { return this->Container::operator[](pos.base()); }
};
 
#endif /* CONVERTIBLE_THROUGH_BASE_HPP */