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Limited number of places where common_type is being used on quantities

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For some specific mathematical types different type might be returned from division, mulitplication, substraction, etc.
std::common_type<> does not have an information which operation is being performed. It is much better to just get
the actual result of specific operation.
This commit is contained in:
Mateusz Pusz
2019-05-07 21:03:58 -06:00
parent cdf9f929c3
commit cf2370b8fe
2 changed files with 69 additions and 54 deletions
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115
src/include/units/quantity.h
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@ -48,6 +48,23 @@ namespace units {
template<typename T>
concept bool Quantity = detail::is_quantity<T>;
// common_quantity
template<Quantity Q1, Quantity Q2, Number Rep>
struct common_quantity;
template<Dimension D, Unit U, Number Rep1, Number Rep2, Number Rep>
struct common_quantity<quantity<D, U, Rep1>, quantity<D, U, Rep2>, Rep> {
using type = quantity<D, U, Rep>;
};
template<Dimension D, Unit U1, Number Rep1, Unit U2, Number Rep2, Number Rep>
struct common_quantity<quantity<D, U1, Rep1>, quantity<D, U2, Rep2>, Rep> {
using type = quantity<D, upcasting_traits_t<unit<D, common_ratio_t<typename U1::ratio, typename U2::ratio>>>, Rep>;
};
template<Quantity Q1, Quantity Q2, Number Rep = std::common_type_t<typename Q1::rep, typename Q2::rep>>
using common_quantity_t = typename common_quantity<Q1, Q2, Rep>::type;
// treat_as_floating_point
template<typename Rep> // todo Conceptify that
@ -217,7 +234,8 @@ namespace units {
[[nodiscard]] constexpr Quantity operator+(const quantity<D, U1, Rep1>& lhs,
const quantity<D, U2, Rep2>& rhs)
{
using ret = std::common_type_t<quantity<D, U1, Rep1>, quantity<D, U2, Rep2>>;
using common_rep = decltype(lhs.count() + rhs.count());
using ret = common_quantity_t<quantity<D, U1, Rep1>, quantity<D, U2, Rep2>, common_rep>;
return ret(ret(lhs).count() + ret(rhs).count());
}
@ -225,58 +243,66 @@ namespace units {
[[nodiscard]] constexpr Quantity operator-(const quantity<D, U1, Rep1>& lhs,
const quantity<D, U2, Rep2>& rhs)
{
using ret = std::common_type_t<quantity<D, U1, Rep1>, quantity<D, U2, Rep2>>;
using common_rep = decltype(lhs.count() - rhs.count());
using ret = common_quantity_t<quantity<D, U1, Rep1>, quantity<D, U2, Rep2>, common_rep>;
return ret(ret(lhs).count() - ret(rhs).count());
}
template<Dimension D, Unit U, Number Rep1, Number Rep2>
[[nodiscard]] quantity<D, U, std::common_type_t<Rep1, Rep2>>
constexpr operator*(const quantity<D, U, Rep1>& q,
const Rep2& v)
// template<Dimension D, Unit U, Number Rep1, Number Rep2>
template<typename D, typename U, typename Rep1, typename Rep2>
requires !Quantity<Rep2>
/* [[nodiscard]]*/ constexpr Quantity operator*(const quantity<D, U, Rep1>& q,
const Rep2& v)
{
using ret = quantity<D, U, std::common_type_t<Rep1, Rep2>>;
using common_rep = decltype(q.count()* v);
using ret = quantity<D, U, common_rep>;
return ret(ret(q).count() * v);
}
template<Number Rep1, Dimension D, Unit U, Number Rep2>
[[nodiscard]] quantity<D, U, std::common_type_t<Rep1, Rep2>>
constexpr operator*(const Rep1& v,
const quantity<D, U, Rep2>& q)
//template<Number Rep1, Dimension D, Unit U, Number Rep2>
template<typename Rep1, typename D, typename U, typename Rep2>
requires !Quantity<Rep1>
/* [[nodiscard]]*/ constexpr Quantity operator*(const Rep1& v,
const quantity<D, U, Rep2>& q)
{
return q * v;
}
template<Dimension D1, Unit U1, Number Rep1, Dimension D2, Unit U2, Number Rep2>
requires treat_as_floating_point<std::common_type_t<Rep1, Rep2>> || (std::ratio_multiply<typename U1::ratio, typename U2::ratio>::den == 1)
/* [[nodiscard]] */ constexpr Quantity operator*(const quantity<D1, U1, Rep1>& lhs,
[[nodiscard]] constexpr Quantity operator*(const quantity<D1, U1, Rep1>& lhs,
const quantity<D2, U2, Rep2>& rhs)
requires treat_as_floating_point<decltype(lhs.count() * rhs.count())> ||
(std::ratio_multiply<typename U1::ratio, typename U2::ratio>::den == 1)
{
using dim = dimension_multiply_t<D1, D2>;
using ret = quantity<dim, upcasting_traits_t<unit<dim, std::ratio_multiply<typename U1::ratio, typename U2::ratio>>>, std::common_type_t<Rep1, Rep2>>;
using common_rep = decltype(lhs.count() * rhs.count());
using ret = quantity<dim, upcasting_traits_t<unit<dim, std::ratio_multiply<typename U1::ratio, typename U2::ratio>>>, common_rep>;
return ret(lhs.count() * rhs.count());
}
template<Number Rep1, Dimension D, Unit U, Number Rep2>
[[nodiscard]] quantity<dim_invert_t<D>, upcasting_traits_t<unit<dim_invert_t<D>, std::ratio<U::ratio::den, U::ratio::num>>>, std::common_type_t<Rep1, Rep2>>
constexpr operator/(const Rep1& v,
const quantity<D, U, Rep2>& q)
// template<Number Rep1, Dimension D, Unit U, Number Rep2>
template<typename Rep1, typename D, typename U, typename Rep2>
[[nodiscard]] constexpr Quantity operator/(const Rep1& v,
const quantity<D, U, Rep2>& q)
{
Expects(q != std::decay_t<decltype(q)>(0));
using dim = dim_invert_t<D>;
using ret = quantity<dim, upcasting_traits_t<unit<dim, std::ratio<U::ratio::den, U::ratio::num>>>, std::common_type_t<Rep1, Rep2>>;
using den = quantity<D, U, std::common_type_t<Rep1, Rep2>>;
using common_rep = decltype(v / q.count());
using ret = quantity<dim, upcasting_traits_t<unit<dim, std::ratio<U::ratio::den, U::ratio::num>>>, common_rep>;
using den = quantity<D, U, common_rep>;
return ret(v / den(q).count());
}
template<Dimension D, Unit U, Number Rep1, Number Rep2>
[[nodiscard]] quantity<D, U, std::common_type_t<Rep1, Rep2>>
constexpr operator/(const quantity<D, U, Rep1>& q,
const Rep2& v)
// template<Dimension D, Unit U, Number Rep1, Number Rep2>
template<typename D, typename U, typename Rep1, typename Rep2>
[[nodiscard]] constexpr Quantity operator/(const quantity<D, U, Rep1>& q,
const Rep2& v)
{
Expects(v != Rep2{0});
using ret = quantity<D, U, std::common_type_t<Rep1, Rep2>>;
using common_rep = decltype(q.count() / v);
using ret = quantity<D, U, common_rep>;
return ret(ret(q).count() / v);
}
@ -286,19 +312,22 @@ namespace units {
{
Expects(rhs != std::decay_t<decltype(rhs)>(0));
using cq = std::common_type_t<quantity<D, U1, Rep1>, quantity<D, U2, Rep2>>;
using common_rep = decltype(lhs.count() / rhs.count());
using cq = common_quantity_t<quantity<D, U1, Rep1>, quantity<D, U2, Rep2>, common_rep>;
return cq(lhs).count() / cq(rhs).count();
}
template<Dimension D1, Unit U1, Number Rep1, Dimension D2, Unit U2, Number Rep2>
requires treat_as_floating_point<std::common_type_t<Rep1, Rep2>> || (std::ratio_divide<typename U1::ratio, typename U2::ratio>::den == 1)
/* [[nodiscard]] */ constexpr Quantity operator/(const quantity<D1, U1, Rep1>& lhs,
const quantity<D2, U2, Rep2>& rhs)
[[nodiscard]] constexpr Quantity operator/(const quantity<D1, U1, Rep1>& lhs,
const quantity<D2, U2, Rep2>& rhs)
requires treat_as_floating_point<decltype(lhs.count() / rhs.count())> ||
(std::ratio_divide<typename U1::ratio, typename U2::ratio>::den == 1)
{
Expects(rhs != std::decay_t<decltype(rhs)>(0));
using common_rep = decltype(lhs.count() / rhs.count());
using dim = dimension_divide_t<D1, D2>;
using ret = quantity<dim, upcasting_traits_t<unit<dim, std::ratio_divide<typename U1::ratio, typename U2::ratio>>>, std::common_type_t<Rep1, Rep2>>;
using ret = quantity<dim, upcasting_traits_t<unit<dim, std::ratio_divide<typename U1::ratio, typename U2::ratio>>>, common_rep>;
return ret(lhs.count() / rhs.count());
}
@ -306,7 +335,8 @@ namespace units {
[[nodiscard]] constexpr Quantity operator%(const quantity<D, U, Rep1>& q,
const Rep2& v)
{
using ret = quantity<D, U, std::common_type_t<Rep1, Rep2>>;
using common_rep = decltype(q.count() % v);
using ret = quantity<D, U, common_rep>;
return ret(ret(q).count() % v);
}
@ -314,7 +344,8 @@ namespace units {
[[nodiscard]] constexpr Quantity operator%(const quantity<D, U1, Rep1>& lhs,
const quantity<D, U2, Rep2>& rhs)
{
using ret = std::common_type_t<quantity<D, U1, Rep1>, quantity<D, U2, Rep2>>;
using common_rep = decltype(lhs.count() % rhs.count());
using ret = common_quantity_t<quantity<D, U1, Rep1>, quantity<D, U2, Rep2>, common_rep>;
return ret(ret(lhs).count() % ret(rhs).count());
}
@ -323,7 +354,7 @@ namespace units {
template<Dimension D, Unit U1, Number Rep1, Unit U2, Number Rep2>
[[nodiscard]] constexpr bool operator==(const quantity<D, U1, Rep1>& lhs, const quantity<D, U2, Rep2>& rhs)
{
using ct = std::common_type_t<quantity<D, U1, Rep1>, quantity<D, U2, Rep2>>;
using ct = common_quantity_t<quantity<D, U1, Rep1>, quantity<D, U2, Rep2>>;
return ct(lhs).count() == ct(rhs).count();
}
@ -336,7 +367,7 @@ namespace units {
template<Dimension D, Unit U1, Number Rep1, Unit U2, Number Rep2>
[[nodiscard]] constexpr bool operator<(const quantity<D, U1, Rep1>& lhs, const quantity<D, U2, Rep2>& rhs)
{
using ct = std::common_type_t<quantity<D, U1, Rep1>, quantity<D, U2, Rep2>>;
using ct = common_quantity_t<quantity<D, U1, Rep1>, quantity<D, U2, Rep2>>;
return ct(lhs).count() < ct(rhs).count();
}
@ -359,19 +390,3 @@ namespace units {
}
} // namespace units
namespace std {
template<units::Dimension D, units::Unit U, units::Number Rep1, units::Number Rep2>
struct common_type<units::quantity<D, U, Rep1>, units::quantity<D, U, Rep2>> {
using type = units::quantity<D, U, std::common_type_t<Rep1, Rep2>>;
};
// todo: simplified
template<units::Dimension D, units::Unit U1, units::Number Rep1, units::Unit U2, units::Number Rep2>
struct common_type<units::quantity<D, U1, Rep1>, units::quantity<D, U2, Rep2>> {
using type = units::quantity<D, units::upcasting_traits_t<units::unit<D, units::common_ratio_t<typename U1::ratio, typename U2::ratio>>>,
std::common_type_t<Rep1, Rep2>>;
};
} // namespace std

8
test/test_quantity.cpp
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@ -249,11 +249,11 @@ namespace {
static_assert(Quantity<length<millimeter, int>>);
// common_type
// common_quantity
static_assert(std::is_same_v<std::common_type_t<length<meter, int>, length<kilometer, int>>, length<meter, int>>);
static_assert(std::is_same_v<std::common_type_t<length<kilometer, long long>, length<meter, int>>, length<meter, long long>>);
static_assert(std::is_same_v<std::common_type_t<length<kilometer, long long>, length<millimeter, double>>, length<millimeter, double>>);
static_assert(std::is_same_v<common_quantity_t<length<meter, int>, length<kilometer, int>>, length<meter, int>>);
static_assert(std::is_same_v<common_quantity_t<length<kilometer, long long>, length<meter, int>>, length<meter, long long>>);
static_assert(std::is_same_v<common_quantity_t<length<kilometer, long long>, length<millimeter, double>>, length<millimeter, double>>);
// quantity_cast