magnum/src/Magnum/Math/Unit.h

#ifndef Magnum_Math_Unit_h
#define Magnum_Math_Unit_h
/*
    This file is part of Magnum.

    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019,
                2020, 2021, 2022, 2023 Vladimír Vondruš <mosra@centrum.cz>

    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
    to deal in the Software without restriction, including without limitation
    the rights to use, copy, modify, merge, publish, distribute, sublicense,
    and/or sell copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included
    in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    DEALINGS IN THE SOFTWARE.
*/

/** @file
 * @brief Class @ref Magnum::Math::Unit
 */

#include "Magnum/Math/TypeTraits.h"
#include "Magnum/Math/Tags.h"

namespace Magnum { namespace Math {

/**
@brief Base class for units
@tparam T Underlying data type

@see @ref Deg, @ref Rad
*/
template<template<class> class Derived, class T> class Unit {
    template<template<class> class, class> friend class Unit;

    public:
        typedef T Type;             /**< @brief Underlying data type */

        /**
         * @brief Default constructor
         *
         * Equivalent to @ref Unit(ZeroInitT).
         */
        constexpr /*implicit*/ Unit() noexcept: _value(T(0)) {}

        /** @brief Construct a zero value */
        constexpr explicit Unit(ZeroInitT) noexcept: _value(T(0)) {}

        /** @brief Construct without initializing the contents */
        explicit Unit(Magnum::NoInitT) noexcept {}

        /** @brief Explicit conversion from a unitless type */
        constexpr explicit Unit(T value) noexcept: _value(value) {}

        /** @brief Construct from another underlying type */
        template<class U> constexpr explicit Unit(Unit<Derived, U> value) noexcept: _value(T(value._value)) {}

        /** @brief Explicit conversion to underlying type */
        constexpr explicit operator T() const { return _value; }

        /** @brief Equality comparison */
        constexpr bool operator==(Unit<Derived, T> other) const {
            return TypeTraits<T>::equals(_value, other._value);
        }

        /** @brief Non-equality comparison */
        constexpr bool operator!=(Unit<Derived, T> other) const {
            return !operator==(other);
        }

        /** @brief Less than comparison */
        constexpr bool operator<(Unit<Derived, T> other) const {
            return _value < other._value;
        }

        /** @brief Greater than comparison */
        constexpr bool operator>(Unit<Derived, T> other) const {
            return _value > other._value;
        }

        /** @brief Less than or equal comparison */
        constexpr bool operator<=(Unit<Derived, T> other) const {
            return !operator>(other);
        }

        /** @brief Greater than or equal comparison */
        constexpr bool operator>=(Unit<Derived, T> other) const {
            return !operator<(other);
        }

        /**
         * @brief Promotion
         * @m_since_latest
         *
         * Returns the value as-is.
         */
        constexpr Unit<Derived, T> operator+() const { return *this; }

        /** @brief Negated value */
        constexpr Unit<Derived, T> operator-() const {
            return Unit<Derived, T>(-_value);
        }

        /** @brief Add and assign a value */
        Unit<Derived, T>& operator+=(Unit<Derived, T> other) {
            _value += other._value;
            return *this;
        }

        /** @brief Add a value */
        constexpr Unit<Derived, T> operator+(Unit<Derived, T> other) const {
            return Unit<Derived, T>(_value + other._value);
        }

        /** @brief Subtract and assign a value */
        Unit<Derived, T>& operator-=(Unit<Derived, T> other) {
            _value -= other._value;
            return *this;
        }

        /** @brief Subtract a value */
        constexpr Unit<Derived, T> operator-(Unit<Derived, T> other) const {
            return Unit<Derived, T>(_value - other._value);
        }

        /** @brief Multiply with a number and assign */
        Unit<Derived, T>& operator*=(T number) {
            _value *= number;
            return *this;
        }

        /** @brief Multiply with a number */
        constexpr Unit<Derived, T> operator*(T number) const {
            return Unit<Derived, T>(_value*number);
        }

        /**
         * @brief Multiply a number with a value
         *
         * Same as @ref operator*(T) const.
         */
        constexpr friend Unit<Derived, T> operator*(
            #ifdef DOXYGEN_GENERATING_OUTPUT
            T
            #else
            typename std::common_type<T>::type
            #endif
            number, Unit<Derived, T> value)
        {
            return Unit<Derived, T>{value._value*number};
        }

        /**
         * @brief Multiply an integral value with a floating-point number and assign
         * @m_since_latest
         *
         * Similar to @ref operator*=(T), except that the multiplication is
         * done in floating-point.
         */
        #ifdef DOXYGEN_GENERATING_OUTPUT
        template<class FloatingPoint> Unit<Derived, T>&
        #else
        template<class FloatingPoint, class Integral = T> typename std::enable_if<std::is_integral<Integral>::value && std::is_floating_point<FloatingPoint>::value, Unit<Derived, T>&>::type
        #endif
        operator*=(FloatingPoint number) {
            _value = T(_value*number);
            return *this;
        }

        /**
         * @brief Multiply an integral value with a floating-point number
         * @m_since_latest
         *
         * Similar to @ref operator*(T) const, except that the multiplication
         * is done in floating-point.
        */
        /* Note that this one isn't correctly picked up on MSVC 2015, there's
           an out-of-class overload wrapped in CORRADE_MSVC2015_COMPATIBILITY
           which is (and the two don't conflict, apparently, so both are
           present) */
        #ifdef DOXYGEN_GENERATING_OUTPUT
        template<class FloatingPoint> constexpr Unit<Derived, T>
        #else
        template<class FloatingPoint, class Integral = T> constexpr typename std::enable_if<std::is_integral<Integral>::value && std::is_floating_point<FloatingPoint>::value, Unit<Derived, T>>::type
        #endif
        operator*(FloatingPoint number) const {
            return Unit<Derived, T>{T(_value*number)};
        }

        /**
         * @brief Multiply a floating-point number with an integral value
         * @m_since_latest
         *
         * Same as @ref operator*(FloatingPoint) const.
         */
        #ifdef DOXYGEN_GENERATING_OUTPUT
        template<class FloatingPoint> friend constexpr Unit<Derived, T>
        #else
        template<class FloatingPoint, class Integral = T> friend constexpr typename std::enable_if<std::is_integral<Integral>::value && std::is_floating_point<FloatingPoint>::value, Unit<Derived, T>>::type
        #endif
        operator*(FloatingPoint number, const Unit<Derived, T>& value) {
            return Unit<Derived, T>{T(value._value*number)};
        }

        /** @brief Divide with a number and assign */
        Unit<Derived, T>& operator/=(T number) {
            _value /= number;
            return *this;
        }

        /** @brief Divide with a number */
        constexpr Unit<Derived, T> operator/(T number) const {
            return Unit<Derived, T>(_value/number);
        }

        /**
         * @brief Divide an integral value with a floating-point number and assign
         * @m_since_latest
         *
         * Similar to @ref operator/=(T), except that the division is done in
         * floating-point.
         */
        #ifdef DOXYGEN_GENERATING_OUTPUT
        template<class FloatingPoint> Unit<Derived, T>&
        #else
        template<class FloatingPoint, class Integral = T> typename std::enable_if<std::is_integral<Integral>::value && std::is_floating_point<FloatingPoint>::value, Unit<Derived, T>&>::type
        #endif
        operator/=(FloatingPoint number) {
            _value = T(_value/number);
            return *this;
        }

        /**
         * @brief Divide an integral value with a floating-point number
         * @m_since_latest
         *
         * Similar to @ref operator/(T) const, except that the division is done
         * in floating-point.
        */
        #ifdef DOXYGEN_GENERATING_OUTPUT
        template<class FloatingPoint> constexpr Unit<Derived, T>
        #else
        template<class FloatingPoint, class Integral = T> constexpr typename std::enable_if<std::is_integral<Integral>::value && std::is_floating_point<FloatingPoint>::value, Unit<Derived, T>>::type
        #endif
        operator/(FloatingPoint number) const {
            return Unit<Derived, T>{T(_value/number)};
        }

        /** @brief Ratio of two values */
        constexpr T operator/(Unit<Derived, T> other) const {
            return _value/other._value;
        }

        /**
         * @brief Do modulo of a value and assign
         * @m_since_latest
         *
         * Enabled only for integral types.
         */
        #ifdef DOXYGEN_GENERATING_OUTPUT
        Unit<Derived, T>&
        #else
        template<class Integral = T> typename std::enable_if<std::is_integral<Integral>::value, Unit<Derived, T>&>::type
        #endif
        operator%=(Unit<Derived, T> other) {
            _value %= other._value;
            return *this;
        }

        /**
         * @brief Modulo of a value
         * @m_since_latest
         *
         * Enabled only for integral types.
         */
        #ifdef DOXYGEN_GENERATING_OUTPUT
        constexpr Unit<Derived, T>
        #else
        template<class Integral = T> constexpr typename std::enable_if<std::is_integral<Integral>::value, Unit<Derived, T>>::type
        #endif
        operator%(Unit<Derived, T> other) const {
            return Unit<Derived, T>{_value%other._value};
        }

    private:
        T _value;
};

#ifdef CORRADE_MSVC2015_COMPATIBILITY
/* MSVC 2015 doesn't correctly pick up the in-class inline friend that does
   this, resulting in float*Unit<int> expressions being wrongly executed as
   int*Unit<int> due to an implicit conversion fallback. This overload is
   picked up correctly (and doesn't conflict with the in-class one). See
   UnitTest::multiplyDivideIntegral() for regression tests, the same issue and
   a matching workaround is done in Vector as well. */
template<template<class> class Derived, class FloatingPoint, class Integral> constexpr typename std::enable_if<std::is_integral<Integral>::value && std::is_floating_point<FloatingPoint>::value, Unit<Derived, Integral>>::type operator*(FloatingPoint number, const Unit<Derived, Integral>& value) {
    return value*number;
}
#endif

}}

#endif