log_sink.h

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/*
 * Copyright 2023 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 <string_view>
#include <utility>
 
#include "num_collect/impl/num_collect_export.h"
#include "num_collect/logging/log_level.h"
#include "num_collect/logging/time_stamp.h"
#include "num_collect/util/source_info_view.h"
 
namespace num_collect::logging::sinks {
 
class NUM_COLLECT_EXPORT log_sink {
public:
    using write_function_type = void (*)(void* /*user_data*/,
        time_stamp /*time*/, std::string_view /*tag*/, log_level /*level*/,
        util::source_info_view /*source*/, std::string_view /*body*/) noexcept;
 
    using finalizer_type = void (*)(void* /*user_data*/) noexcept;
 
    log_sink(void* user_data, write_function_type write_function,
        finalizer_type finalizer);
 
    log_sink(const log_sink& obj) noexcept;
 
    log_sink(log_sink&& obj) noexcept;
 
    auto operator=(const log_sink& obj) noexcept -> log_sink&;
 
    auto operator=(log_sink&& obj) noexcept -> log_sink&;
 
    ~log_sink();
 
    void write(time_stamp time, std::string_view tag, log_level level,
        util::source_info_view source, std::string_view body) const noexcept;
 
private:
    struct reference_count;
 
    void* user_data_;
 
    write_function_type write_function_;
 
    finalizer_type finalizer_;
 
    reference_count* reference_count_;
};
 
template <typename T, typename... Args>
[[nodiscard]] auto create_log_sink(Args&&... args) -> log_sink {
    T* ptr = new T(std::forward<Args>(args)...);
    return log_sink(
        ptr,
        [](void* ptr, time_stamp time, std::string_view tag, log_level level,
            util::source_info_view source, std::string_view body) noexcept {
            static_cast<T*>(ptr)->write(time, tag, level, source, body);
        },
        [](void* ptr) noexcept { delete static_cast<T*>(ptr); });
}
 
}  // namespace num_collect::logging::sinks