iteration_layer_handler.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 <atomic>
#include <memory>
 
namespace num_collect::logging::impl {
 
class iteration_layer_handler {
public:
    iteration_layer_handler() = default;
 
    iteration_layer_handler(const iteration_layer_handler&) = delete;
    auto operator=(const iteration_layer_handler&) = delete;
 
    iteration_layer_handler(
        iteration_layer_handler&& /*obj*/) noexcept = default;
 
    auto operator=(iteration_layer_handler&& /*obj*/) noexcept
        -> iteration_layer_handler& = default;
 
    ~iteration_layer_handler() noexcept = default;
 
    void set_iterative() const noexcept { node_->set_iterative(); }
 
    void initialize_lower_layer(iteration_layer_handler& lower_layer) noexcept {
        lower_layer.node_->set_parent(node_);
    }
 
    [[nodiscard]] auto is_upper_layer_iterative() const noexcept -> bool {
        return node_->is_ancestor_node_iterative();
    }
 
private:
    class node {
    public:
        void set_iterative() noexcept { is_iterative_ = true; }
 
        void set_parent(const std::shared_ptr<node>& parent) noexcept {
            parent_ = parent;
        }
 
        [[nodiscard]] auto is_ancestor_node_iterative() const noexcept -> bool {
            const auto locked = parent_.lock();
            if (!locked) {
                return false;
            }
            return locked->is_this_or_ancestor_node_iterative();
        }
 
        void reset() noexcept {
            is_iterative_ = false;
            parent_.reset();
        }
 
    private:
        [[nodiscard]] auto is_this_or_ancestor_node_iterative() const noexcept
            -> bool {
            if (is_iterative_) {
                return true;
            }
            return is_ancestor_node_iterative();
        }
 
        std::atomic<bool> is_iterative_{false};
 
        std::weak_ptr<node> parent_{};
    };
 
    std::shared_ptr<node> node_{std::make_shared<node>()};
};
 
}  // namespace num_collect::logging::impl