Operators.h

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/*
 * Copyright (c) 2020 pongasoft
 *
 * Licensed under the Apache License, Version 2.0 or the MIT license,
 * at your option. You may not use this file except in compliance with
 * one of these licenses. You may obtain copies of the licenses at:
 *
 * https://www.apache.org/licenses/LICENSE-2.0
 * https://opensource.org/licenses/MIT
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 *
 * @author Yan Pujante
 */
 
#pragma once
 
namespace pongasoft::Utils::Operators {

template<typename T>
class Dereferenceable
{
public:
  // LHS is reference, RHS is reference
  friend constexpr bool operator==(T const &lhs, T const &rhs) { return *lhs == *rhs; }
 
  friend constexpr bool operator!=(T const &lhs, T const &rhs) { return !(lhs == rhs); }
 
  friend constexpr bool operator<(T const &lhs, T const &rhs) { return *lhs < *rhs; }
 
  friend constexpr bool operator>(T const &lhs, T const &rhs) { return rhs < lhs; }
 
  friend constexpr bool operator<=(T const &lhs, T const &rhs) { return !(rhs < lhs); }
 
  friend constexpr bool operator>=(T const &lhs, T const &rhs) { return !(lhs < rhs); }
 
  // LHS is reference, RHS is value
  template<typename V>
  friend constexpr bool operator==(T const &lhs, V const &rhs) { return *lhs == rhs; }
 
  template<typename V>
  friend constexpr bool operator!=(T const &lhs, V const &rhs) { return !(lhs == rhs); }
 
  template<typename V>
  friend constexpr bool operator<(T const &lhs, V const &rhs) { return *lhs < rhs; }
 
  template<typename V>
  friend constexpr bool operator>(T const &lhs, V const &rhs) { return !(lhs < rhs) && lhs != rhs; }
 
  template<typename V>
  friend constexpr bool operator<=(T const &lhs, V const &rhs) { return !(rhs < lhs); }
 
  template<typename V>
  friend constexpr bool operator>=(T const &lhs, V const &rhs) { return !(lhs < rhs); }
 
  // LHS is value, RHS is reference
  template<typename V>
  friend constexpr bool operator==(V const &lhs, T const &rhs) { return rhs == lhs; }
 
  template<typename V>
  friend constexpr bool operator!=(V const &lhs, T const &rhs) { return !(lhs == rhs); }
 
  template<typename V>
  friend constexpr bool operator<(V const &lhs, T const &rhs) { return rhs > lhs; }
 
  template<typename V>
  friend constexpr bool operator>(V const &lhs, T const &rhs) { return rhs < lhs; }
 
  template<typename V>
  friend constexpr bool operator<=(V const &lhs, T const &rhs) { return !(rhs < lhs); }
 
  template<typename V>
  friend constexpr bool operator>=(V const &lhs, T const &rhs) { return !(lhs < rhs); }
};
 
}