distance_base.h

// Description: Distance CRTP base-class
// Documentation: norms.txt

#ifndef PASTELMATH_DISTANCE_BASE_H
#define PASTELMATH_DISTANCE_BASE_H

#include "pastel/math/distance/distance_concept.h"

#include <boost/operators.hpp>

namespace Pastel
{

    //! Distance CRTP base-class
    /*!
   Automatically implements functions required by the
   Distance concept. The Derived class only needs to
   implement operator*=, replace(), and operator~,
   and this class provides <, <=, >=, >, ==, !=, /=, 
   set().
   */
    template <typename Derived, typename Real_>
    struct DistanceBase
    : boost::totally_ordered<Derived
    , boost::totally_ordered2<Derived, Real_
    , boost::multipliable<Derived, Real_
    , boost::dividable<Derived, Real_
    > > > >
    {
        using Real = Real_;

        friend bool operator<(const Derived& left, const Derived& right) {
            return ~left < ~right;
        }

        friend bool operator==(const Derived& left, const Derived& right) {
            return ~left == ~right;
        }

        friend bool operator<(const Derived& left, const Real& right) {
            return left < Derived(right);
        }

        friend bool operator==(const Derived& left, const Real& right) {
            return left == Derived(right);
        }

        friend Derived& operator/=(const Derived& left, const Real& amount) {
            return left *= inverse(amount);
        }

        Derived& set(integer axis, const Real& amount) {
            Derived& self = (Derived&)*this;
            self.replace(axis, 0, amount);
            return self;
        }
    };

}

#endif