equator.hpp

Go to the documentation of this file.

#pragma once
#include "../iequality_comparer.hpp"
#include "../../../object.hpp"
#include "../../../iequatable.hpp"
#include <type_traits>

namespace xtd {
  namespace collections {
    namespace generic {
      namespace helpers {
        template<class value_t>
        struct equator {
          
          using first_argument_type = value_t;
          using second_argument_type = value_t;
          using result_type = bool;
          
          
          equator() = default;
          explicit equator(const xtd::collections::generic::iequality_comparer<value_t>& comparer) : comparer {&comparer} {}
          
          
          auto operator()(const first_argument_type& a, const second_argument_type& b) const -> result_type {
            if (&a == &b) return true;
            if (comparer) return comparer->equals(a, b);
            if constexpr(std::is_polymorphic_v<first_argument_type> && std::is_base_of_v<xtd::iequatable<first_argument_type>, first_argument_type>) return static_cast<const xtd::iequatable<first_argument_type>&>(a).equals(b);
            else if constexpr(std::is_polymorphic_v<first_argument_type> && std::is_base_of_v<xtd::object, first_argument_type>) return static_cast<const xtd::object&>(a).equals(b);
            else if constexpr(std::equality_comparable<first_argument_type>) return a == b;
            else return false;
          }

          
        private:
          const xtd::collections::generic::iequality_comparer<value_t>* comparer = nullptr;
        };
      }
    }
  }
}