Log.hpp

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#pragma once
#include <iostream>
#include <functional>
#include <boost/date_time.hpp>
 
 
namespace Log
{
    enum struct LogLevel
    {
        None = 0, 
        Error = 1, 
        Warning = 2, 
        Info = 3, 
        Debug = 4 
    };
 
    class Logstream;
 
    typedef std::function<Logstream & (Logstream &)> StructManipulator;
 
    typedef Logstream &(*Manipulator)(Logstream &);
 
    class Logstream
    {
        friend Logstream &endl(Logstream &ls);
        friend StructManipulator setDisplayLogLevel(const Log::LogLevel logLevel);
        friend StructManipulator setLogLevel(const Log::LogLevel logLevel);
    public:
        Logstream(std::ostream &logTarget) : _logTarget(logTarget), _constructionTime(boost::posix_time::microsec_clock::local_time())
        {
            _carriageReturn = true;
            _displayLogLevel = Log::LogLevel::Info;
            _streamLogLevel = Log::LogLevel::Info;
        };
 
        template <class T> friend Logstream &operator<<(Logstream &ls, const T &rhs)
        {
            if (ls._displayLogLevel < ls._streamLogLevel) return ls;
            if (ls._streamLogLevel == Log::LogLevel::Warning) ls._logTarget << "\033[31m";
            if (ls._carriageReturn)
            {
                float dt = float((boost::posix_time::microsec_clock::local_time() - ls._constructionTime).total_microseconds());
                ls._logTarget << "[" << std::fixed << std::setprecision(6) << dt / 1000000.0f << "][";
                if (ls._streamLogLevel == LogLevel::Debug) ls._logTarget << "D";
                else if (ls._streamLogLevel == LogLevel::Info) ls._logTarget << "I";
                else if (ls._streamLogLevel == LogLevel::Warning) ls._logTarget << "W";
                else if (ls._streamLogLevel == LogLevel::Error) ls._logTarget << "E";
                ls._logTarget << "] ";
                ls._carriageReturn = false;
            }
            ls._logTarget << rhs;
            if (ls._streamLogLevel == Log::LogLevel::Warning) ls._logTarget << "\033[0m";
 
            return ls;
        }
 
        Logstream &operator<<(const Log::LogLevel &rhs)
        {
            _streamLogLevel = rhs;
            return *this;
        }
 
        Logstream &operator<<(const Manipulator &rhs)
        {
            return rhs(*this);
        }
 
        Logstream &operator<<(const StructManipulator &rhs)
        {
            return rhs(*this);
        }
 
    private:
        std::ostream &_logTarget; 
        boost::posix_time::ptime _constructionTime; 
 
        bool _carriageReturn; 
        Log::LogLevel _displayLogLevel; 
        Log::LogLevel _streamLogLevel; 
    };
 
    #pragma region Manipulators
 
    inline Logstream &endl(Logstream &ls)
    {
        if (ls._displayLogLevel >= ls._streamLogLevel)
        {
            ls._logTarget << std::endl;
            ls._carriageReturn = true;
        }
        return ls;
    }
 
    inline StructManipulator setDisplayLogLevel(const Log::LogLevel logLevel)
    {
        auto manipulator = [logLevel](Logstream &ls)->Logstream &
        {
            ls._displayLogLevel = logLevel;
            return ls;
        };
        return manipulator;
    }
 
    inline StructManipulator setLogLevel(const Log::LogLevel logLevel)
    {
        auto manipulator = [logLevel](Logstream &ls)->Logstream &
        {
            ls._streamLogLevel = logLevel;
            return ls;
        };
        return manipulator;
    }
    #pragma endregion
 
    extern Logstream log; 
}