代码计时工具类stop_watch

//copy from spdlog
#pragma once
#include <chrono>
#include <iostream>
class stopwatch
{
    using clock = std::chrono::steady_clock;
    std::chrono::time_point<clock> start_tp_;

public:
    stopwatch()
        : start_tp_{clock::now()}
    {}

    std::chrono::duration<double> elapsed() const
    {
        return std::chrono::duration<double>(clock::now() - start_tp_);
    }

    void reset()
    {
        start_tp_ = clock::now();
    }
};

#define STOP_WATCH(fun) do {\
        stopwatch sw;\
        fun();\
        std::cout << #fun " Elapsed second: " << (sw.elapsed().count()) << '\n';\
    }while(0)