spdlog/include/c11log/formatter.h

#pragma once

#include <string>
#include <chrono>
#include <functional>
#include <sstream>
#include <iomanip>
#include <thread>

#include "common_types.h"
#include "details/os.h"

namespace c11log
{
namespace formatters
{

typedef std::function<std::string(const std::string& logger_name, const std::string&, level::level_enum, const c11log::log_clock::time_point&)> format_fn;


class formatter
{
public:
    formatter() {}
    virtual ~formatter() {}
    virtual void format_header(const std::string& logger_name, level::level_enum level, const log_clock::time_point& tp, std::ostream& dest) = 0;
};


class default_formatter: public formatter
{
public:
    // Format: [2013-12-29 01:04:42.900] [logger_name:Info] Message body
    void format_header(const std::string& logger_name, level::level_enum level, const log_clock::time_point& tp, std::ostream& dest) override {
        _format_time(tp, dest);
        dest << " [" <<  logger_name << ":" << c11log::level::to_str(level) << "] ";
    }
private:
    void _format_time(const log_clock::time_point& tp, std::ostream &dest);

};
} //namespace formatter
} //namespace c11log



inline void c11log::formatters::default_formatter::_format_time(const log_clock::time_point& tp, std::ostream &dest)
{

#ifdef _MSC_VER
    __declspec(thread) static std::tm last_tm = { 0, 0, 0, 0, 0, 0, 0, 0, 0};
    __declspec(thread) static char last_time_str[64];
#else
    thread_local static std::tm last_tm = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
    thread_local static char last_time_str[64];
#endif

    auto tm_now = details::os::localtime(log_clock::to_time_t(tp));
    using namespace c11log::details::os;
    if(last_tm != tm_now) {
#ifdef _MSC_VER
        ::sprintf_s
#else
        ::snprintf
#endif
        (last_time_str, sizeof(last_time_str), "[%d-%02d-%02d %02d:%02d:%02d]",
         tm_now.tm_year + 1900,
         tm_now.tm_mon + 1,
         tm_now.tm_mday,
         tm_now.tm_hour,
         tm_now.tm_min,
         tm_now.tm_sec);
        last_tm = tm_now;
    }
    dest << last_time_str;
}