unit.h

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#pragma once
#include <stdint.h>
 
namespace unit {
 
enum UnitBase : uint8_t {
    Millimeter,
    Degree,
};
 
enum UnitType : uint8_t {
    Lenght,
    Speed,
    Accel,
};
 
template <typename T, UnitBase B, UnitType U>
struct Unit {
    T v;
 
    static constexpr UnitBase base = B;
    static constexpr UnitType unit = U;
 
    typedef T type_t;
    typedef Unit<T, B, U> self_t;
 
    // same-type operations
    constexpr self_t operator+(const self_t r) const { return { v + r.v }; }
    constexpr self_t operator-(const self_t r) const { return { v - r.v }; }
    constexpr self_t operator-() const { return { -v }; }
    constexpr self_t operator*(const self_t r) const { return { v * r.v }; }
    constexpr self_t operator/(const self_t r) const { return { v / r.v }; }
 
    // allow an unitless multiplier to scale the quantity: U * f => U
    constexpr self_t operator*(const long double f) const { return { (T)(v * f) }; }
    constexpr self_t operator/(const long double f) const { return { (T)(v / f) }; }
};
 
// complementary f * U => U * f
template <typename T, UnitBase B, UnitType U>
constexpr Unit<T, B, U> operator*(const long double f, const Unit<T, B, U> u) { return u * f; }
 
// Millimiters
typedef Unit<long double, Millimeter, Lenght> U_mm;
typedef Unit<long double, Millimeter, Speed> U_mm_s;
typedef Unit<long double, Millimeter, Accel> U_mm_s2;
 
static constexpr U_mm operator"" _mm(long double mm) {
    return { mm };
}
 
static constexpr U_mm_s operator"" _mm_s(long double mm_s) {
    return { mm_s };
}
 
static constexpr U_mm_s2 operator"" _mm_s2(long double mm_s2) {
    return { mm_s2 };
}
 
// Degrees
typedef Unit<long double, Degree, Lenght> U_deg;
typedef Unit<long double, Degree, Speed> U_deg_s;
typedef Unit<long double, Degree, Accel> U_deg_s2;
 
static constexpr U_deg operator"" _deg(long double deg) {
    return { deg };
}
 
static constexpr U_deg_s operator"" _deg_s(long double deg_s) {
    return { deg_s };
}
 
static constexpr U_deg_s2 operator"" _deg_s2(long double deg_s2) {
    return { deg_s2 };
}
 
} // namespace unit
 
// Inject literal operators into the global namespace for convenience
using unit::operator"" _mm;
using unit::operator"" _mm_s;
using unit::operator"" _mm_s2;
using unit::operator"" _deg;
using unit::operator"" _deg_s;
using unit::operator"" _deg_s2;