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mp-units/src/core/include/units/reference.h
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// The MIT License (MIT)
//
// Copyright (c) 2018 Mateusz Pusz
//
// 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.
#pragma once
#include <units/bits/quantity_concepts.h>
#include <units/quantity_spec.h>
#include <units/unit.h>
namespace units {
/**
* @brief Quantity reference type
*
* Quantity reference describes all the properties of a quantity besides its
* representation type.
*
* In most cases this class template is not explicitly instantiated by the user.
* It is implicitly instantiated by the library's framework while binding a quantity
* specification with a compatible unit.
*
* @code{.cpp}
* Reference auto kmph = isq::speed[km / h];
* quantity_of<isq::speed[km / h]> auto speed = 90 * kmph;
* @endcode
*
* The following syntaxes are not allowed:
* `2 / kmph`, `kmph * 3`, `kmph / 4`, `70 * isq::length[km] / isq:time[h]`.
*/
template<QuantitySpec auto Q, Unit auto U>
struct reference {
static constexpr QuantitySpec auto quantity_spec = Q;
static constexpr Dimension auto dimension = Q.dimension;
static constexpr Unit auto unit = U;
};
// Reference
template<Reference R1, Reference R2>
[[nodiscard]] consteval reference<R1::quantity_spec * R2::quantity_spec, R1::unit * R2::unit> operator*(R1, R2)
{
return {};
}
template<Reference R1, Reference R2>
[[nodiscard]] consteval reference<R1::quantity_spec / R2::quantity_spec, R1::unit / R2::unit> operator/(R1, R2)
{
return {};
}
template<Representation Rep, Reference R>
[[nodiscard]] constexpr quantity<R{}, Rep> operator*(const Rep& lhs, R)
{
return quantity<R{}, Rep>(lhs);
}
void /*Use `q * (1 * r)` rather than `q * r`.*/ operator*(Quantity auto, Reference auto) = delete;
template<Reference R1, Reference R2>
[[nodiscard]] consteval bool operator==(R1, R2)
{
return R1::quantity_spec == R2::quantity_spec && R1::unit == R2::unit;
}
template<Reference R1, Reference R2>
[[nodiscard]] consteval bool interconvertible(R1, R2)
{
return interconvertible(R1::quantity_spec, R2::quantity_spec) && interconvertible(R1::unit, R2::unit);
}
[[nodiscard]] consteval auto common_reference(Reference auto r1, Reference auto r2, Reference auto... rest)
requires requires {
{
common_quantity_spec(r1.quantity_spec, r2.quantity_spec, rest.quantity_spec...)
} -> QuantitySpec;
{
common_unit(r1.unit, r2.unit, rest.unit...)
} -> Unit;
}
{
return reference<common_quantity_spec(r1.quantity_spec, r2.quantity_spec, rest.quantity_spec...),
common_unit(r1.unit, r2.unit, rest.unit...)>{};
}
} // namespace units