euclidean_distance.h

// Description: Euclidean distance
// Documentation: distances.txt

#ifndef PASTELMATH_EUCLIDEAN_DISTANCE_H
#define PASTELMATH_EUCLIDEAN_DISTANCE_H

#include "pastel/sys/mytypes.h"
#include "pastel/math/distance/distance_concept.h"
#include "pastel/math/distance/distance_base.h"
#include "pastel/sys/math/powers.h"

#include <cmath>

namespace Pastel
{

    template <typename Real>
    class Euclidean_Distance
    : public DistanceBase<Euclidean_Distance<Real>, Real>
    {
    public:
        using Real_ = Real;

        explicit Euclidean_Distance(const Real& distance = 0) 
        : distance_(square(distance))
        {}

        Euclidean_Distance(Distance_Native, const Real& distance)
        : distance_(abs(distance))
        {}

        Euclidean_Distance(const Euclidean_Distance&) = default;
        Euclidean_Distance(Euclidean_Distance&&) = default;
        Euclidean_Distance& operator=(const Euclidean_Distance&) = default;

        explicit operator Real() const {
            using std::sqrt;
            return sqrt(distance_);
        }

        const Real& operator~() const {
            return distance_;
        }

        decltype(auto) replace(integer axis, const Real& from, const Real& to) {
            distance_ += square(to) - square(from);
            return *this;
        }

        decltype(auto) operator*=(const Real& amount) {
            distance_ *= square(amount);
            return *this;
        }

    private:
        Real distance_;
    };

}

#endif