coordinate_operator_bool_helper.hpp

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#ifndef DXLE_INC_BASIC_TYPES_COORDINATE_OPERATOR_BOOL_HELPER_HPP_
#define DXLE_INC_BASIC_TYPES_COORDINATE_OPERATOR_BOOL_HELPER_HPP_
#include "dxlibex/type_traits/is_castable.hpp"
#include "dxlibex/type_traits/is_well_format.hpp"
#include "dxlibex/type_traits/enable_if.hpp"
#include "dxlibex/config/defines.h"
namespace dxle {
    namespace detail {
        //operator bool
        //1. operator bool
        //2. operator != (nullptr)
        //3. default constector + operator !=

        template <
            typename T,
            bool has_operator_bool = !std::is_scalar<T>::value && is_castable<T, bool>::value,
            bool has_operator_notequal_to_zero = has_operator_notequal_to_zero<const T>::value,
            bool is_compareable_with_default_ctor = std::is_default_constructible<T>::value && has_operator_notequal_to_this<T>::value
        >
        struct operator_bool_helper_impl;
        //1. operator bool
        template<typename T, bool has_operator_notequal_to_zero, bool is_compareable_with_default_ctor>
        struct operator_bool_helper_impl<T, true, has_operator_notequal_to_zero, is_compareable_with_default_ctor> {
            DXLE_CONSTEXPR bool operator()(const T& first, const T& second) const DXLE_NOEXCEPT_IF_EXPR(static_cast<bool>(first)) {
                return static_cast<bool>(first) || static_cast<bool>(second);
            }
            DXLE_CONSTEXPR bool operator()(const T& first, const T& second, const T& third) const DXLE_NOEXCEPT_IF_EXPR(static_cast<bool>(first)) {
                return static_cast<bool>(first) || static_cast<bool>(second) || static_cast<bool>(third);
            }
        };
        //2. operator != (nullptr)
        template<typename T, bool is_compareable_with_default_ctor>
        struct operator_bool_helper_impl<T, false, true, is_compareable_with_default_ctor> {
            DXLE_CONSTEXPR bool operator()(const T& first, const T& second) const DXLE_NOEXCEPT_IF_EXPR(first != 0) {
                return first != 0 || second != 0;
            }
            DXLE_CONSTEXPR bool operator()(const T& first, const T& second, const T& third) const DXLE_NOEXCEPT_IF_EXPR(first != 0) {
                return first != 0 || second != 0 || third != 0;
            }
        };
        //3. default constector + operator !=
        template<typename T>
        struct operator_bool_helper_impl<T, false, false, true> {
            DXLE_CONSTEXPR bool operator()(const T& first, const T& second) const DXLE_NOEXCEPT_IF_EXPR(first != T{}) {
                return first != T{} || second != T{};
            }
            DXLE_CONSTEXPR bool operator()(const T& first, const T& second, const T& third) const DXLE_NOEXCEPT_IF_EXPR(first != T{}) {
                return first != T{} || second != T{} || third != T{};
            }
        };

        template<typename T, enable_if_t<std::is_arithmetic<T>::value, nullptr_t> = nullptr>
        DXLE_CONSTEXPR inline bool operator_bool_helper(const T& first, const T& second)
            DXLE_NOEXCEPT_IF_EXPR(dxle::detail::operator_bool_helper_impl<T>()(first, second))
        {
            return dxle::detail::operator_bool_helper_impl<T>()(first, second);
        }
        template<typename T, enable_if_t<std::is_arithmetic<T>::value, nullptr_t> = nullptr>
        DXLE_CONSTEXPR inline bool operator_bool_helper(const T& first, const T& second, const T& third)
            DXLE_NOEXCEPT_IF_EXPR(dxle::detail::operator_bool_helper_impl<T>()(first, second, third))
        {
            return dxle::detail::operator_bool_helper_impl<T>()(first, second, third);
        }
    }
}
#endif //DXLE_INC_BASIC_TYPES_COORDINATE_OPERATOR_BOOL_HELPER_HPP_