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xo-unit: quantity: + compare() + operator<=>

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Roland Conybeare 2024-04-17 20:53:25 -04:00
commit 39ca2aa9f4
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55
include/xo/unit/quantity.hpp
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@ -440,6 +440,61 @@ namespace xo {
}
///@}
/** @defgroup quantity-comparisonsupport **/
///@{
/** @brief compare this quantity with another, return 3-way comparison
*
* @pre arguments must be quantities having the same dimension
*
* @param y rhs quantity to compare
* @return signed integer; {-ve, 0, +ve} when @c *this is {less than, equal, greater than} @p y
**/
template <typename Quantity2>
requires quantity_concept<Quantity2> && same_dimension_v<unit_type, typename Quantity2::unit_type>
auto compare(Quantity2 y) const {
/* convert y to same {units, repr} as *this */
quantity y2 = y;
auto cmp = (this->scale_ <=> y2.scale());
return cmp;
}
///@}
/** @defgroup quantity-comparison **/
///@{
/** @brief 3-way comparison of two quantities
*
* @pre arguments must be quantities having the same dimension
*
* @param y rhs quantity to compare
* @return std::partial_ordering
**/
template <typename Quantity2>
requires quantity_concept<Quantity2> && same_dimension_v<unit_type, typename Quantity2::unit_type>
auto operator<=>(Quantity2 y) const {
return this->compare(y);
}
/** @brief compare two quantities for equality
*
* Although compiler generates this (due to presence of 3-way comparison operator),
* it flags ambiguous overload when included alongside .h files from std::distribution.
* Look like ambiguity would need to be resolved by a header change
**/
template <typename Quantity2>
requires quantity_concept<Quantity2> && same_dimension_v<unit_type, typename Quantity2::unit_type>
bool operator==(Quantity2 y) const {
return std::is_eq(this->compare(y));
}
template <typename Quantity2>
requires quantity_concept<Quantity2> && same_dimension_v<unit_type, typename Quantity2::unit_type>
bool operator!=(Quantity2 y) const {
return std::is_neq(this->compare(y));
}
/** @addtogroup quantity-unit-conversion **/
///@{
/** @brief convert to quantity with same dimension, different {unit_type, repr_type}