tagged_scalar.hpp

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/*
 * RESTinio
 */

/*!
 * @file
 * @brief Helper template for defining tagged scalar types.
 *
 * @since v.0.6.12
 */

#pragma once

#include <restinio/compiler_features.hpp>

#include <type_traits>

namespace restinio
{

namespace utils
{

//
// tagged_scalar_t
//
/*!
 * @brief Helper template for defining tagged scalar types.
 *
 * Usage example:
 * @code
 * struct max_parallel_connections_tag {};
 * using max_parallel_connections_t = tagged_scalar_t<
 *      std::size_t, max_parallel_connections_tag >;
 *
 * struct max_active_accepts_tag {};
 * using max_active_accepts_t = tagged_scalar_t<
 *      std::size_t, max_active_accepts_tag >;
 *
 * class limiter_t
 * {
 * public:
 *  limiter_t(
 *      max_parallel_connections_t parallel_connections,
 *      max_active_accepts_t active_accepts);
 *  ...
 * };
 * @endcode
 *
 * @since v.0.6.12
 */
template< typename Scalar, typename Tag >
class tagged_scalar_t
{
    static_assert( std::is_scalar<Scalar>::value,
            "Scalar is expected to be scalar type" );

    Scalar m_value;

public:
    constexpr explicit tagged_scalar_t( Scalar value ) noexcept
        :   m_value{ value }
    {}

    [[nodiscard]]
    constexpr Scalar
    value() const noexcept { return m_value; }
};

} /* namespace utils */

} /* namespace restinio */