scaled_scalar.hpp

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// SPDX-License-Identifier: BSL-1.0
 
#ifndef TETL_LINALG_SCALED_SCALAR_HPP
#define TETL_LINALG_SCALED_SCALAR_HPP
 
#include <etl/_linalg/proxy_reference.hpp>
#include <etl/_type_traits/declval.hpp>
 
namespace etl::linalg::detail {
 
template <typename ScalingFactor, typename ReferenceValue>
concept scalable = requires { declval<ScalingFactor>() * declval<ReferenceValue>(); };
 
template <typename ScalingFactor, typename Reference, typename ReferenceValue>
    requires(scalable<ScalingFactor, ReferenceValue>)
struct scaled_scalar
    : proxy_reference<Reference, ReferenceValue, scaled_scalar<ScalingFactor, Reference, ReferenceValue>> {
    using value_type = decltype(declval<ScalingFactor>() * ReferenceValue(declval<Reference>()));
 
    constexpr explicit scaled_scalar(ScalingFactor const& scalingFactor, Reference const& reference)
        : proxy_reference<Reference, ReferenceValue, scaled_scalar<ScalingFactor, Reference, ReferenceValue>>{reference}
        , _scalingFactor{scalingFactor}
    {
    }
 
    [[nodiscard]] constexpr auto to_value(Reference reference) const -> value_type
    {
        return _scalingFactor * ReferenceValue(reference);
    }
 
private:
    ScalingFactor _scalingFactor;
};
 
} // namespace etl::linalg::detail
 
#endif // TETL_LINALG_SCALED_SCALAR_HPP