vector2_ref.hpp

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#pragma once
 
#include "vector2.hpp"
 
#if __cpp_constexpr >= 201304
#    define CONSTEXPR14 constexpr
#else
#    define CONSTEXPR14 inline
#endif
 
static double global_vector2_ref_dummy = 0.0;
 
namespace ginger {
 
    class Vector2Ref {
      public:
        double& _x;
        double& _y;
 
        constexpr Vector2Ref() noexcept
            : _x{global_vector2_ref_dummy}, _y{global_vector2_ref_dummy} {}
 
        constexpr Vector2Ref(double& x, double& y) noexcept : _x{x}, _y{y} {}
 
        constexpr auto x() const noexcept -> const double& { return this->_x; }
 
        constexpr auto y() const noexcept -> const double& { return this->_y; }
 
        constexpr auto dot(const Vector2Ref& other) const -> double {
            return this->_x * other._x + this->_y * other._y;
        }
 
        constexpr auto cross(const Vector2Ref& other) const -> double {
            return this->_x * other._y - other._x * this->_y;
        }
 
 
        CONSTEXPR14 auto operator+=(const Vector2<double, double>& other) -> Vector2Ref& {
            this->_x += other.x();
            this->_y += other.y();
            return *this;
        }
 
        CONSTEXPR14 auto operator-=(const Vector2<double, double>& other) -> Vector2Ref& {
            this->_x -= other.x();
            this->_y -= other.y();
            return *this;
        }
 
        CONSTEXPR14 auto operator*=(const double& alpha) -> Vector2Ref& {
            this->_x *= alpha;
            this->_y *= alpha;
            return *this;
        }
 
        CONSTEXPR14 auto operator/=(const double& alpha) -> Vector2Ref& {
            this->_x /= alpha;
            this->_y /= alpha;
            return *this;
        }
 
        CONSTEXPR14 auto operator*(const double& alpha) const -> Vector2<double, double> {
            return Vector2<double, double>{this->x() * alpha, this->y() * alpha};
        }
 
 
        template <class Stream> friend auto operator<<(Stream& out, const Vector2Ref& vec)
            -> Stream& {
            out << "{" << vec.x() << ", " << vec.y() << "}";
            return out;
        }
    };
}  // namespace ginger