member_variable_iteration_parameter_value.h

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/*
 * Copyright 2022 MusicScience37 (Kenta Kabashima)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#pragma once
 
#include "num_collect/base/exception.h"
#include "num_collect/logging/concepts/formattable_iteration_parameter_value.h"
 
namespace num_collect::logging::iterations {
 
template <typename Algorithm,
    concepts::formattable_iteration_parameter_value Value>
class member_variable_iteration_parameter_value {
public:
    explicit member_variable_iteration_parameter_value(
        const Value Algorithm::* value)
        : value_(value) {}
 
    [[nodiscard]] auto get() const -> const Value& {
        throw invalid_argument(
            "Evaluation of this parameter value requires the pointer to the "
            "algorithm.");
    }
 
    [[nodiscard]] auto get(const Algorithm* algorithm) const noexcept
        -> const Value& {
        return algorithm->*value_;
    }
 
private:
    const Value Algorithm::* value_;
};
 
}  // namespace num_collect::logging::iterations