logger.hh

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/*!
 *
 * Copyright (C) 2015 Technical University of Liberec.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License version 3 as published by the
 * Free Software Foundation. (http://www.gnu.org/licenses/gpl-3.0.en.html)
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
 *
 *
 * @file    logger.hh
 * @brief
 */

#ifndef LOGGER_HH_
#define LOGGER_HH_


#include <iostream>
#include <algorithm>            // for forward
#include <string>               // for string
#include <sstream>
//#include <vector>

#include "system/fmt/format.h"



/**
 * @brief Helper class, store mask specifying streams
 *
 * Defines masks of all used streams as static methods and allows combining and comparing masks using
 * the overloaded operators.
 */
class StreamMask {
public:
    /// Empty constructor
    StreamMask()
    : mask_(0) {}

    /// Constructor set \p mask_ value
    StreamMask(int mask)
    : mask_(mask) {}

    /// Predefined mask of std::cout output
    static StreamMask cout;

    /// Predefined mask of std::cerr output
    static StreamMask cerr;

    /// Predefined mask of log file output
    static StreamMask log;

    // Overload & operator
    StreamMask operator &(const StreamMask &other);

    // Overload | operator
    StreamMask operator |(const StreamMask &other);

    // Overload () operator
    int operator()(void);

private:
    int mask_;
};


/**
 * @brief Class for storing logger messages.
 *
 * Allow define different levels of log messages and distinguish output streams
 * for individual leves. These output streams are -
 *  - standard console output (std::cout)
 *  - standard error output (std::cerr)
 *  - file output (see \p LoggerOptions class)
 *
 * Logger distinguishes four type of levels -
 *  - warning: printed to standard error and file output
 *  - message: printed to standard console and file output
 *  - log: printed to file output
 *  - debug: printed to file output (level is used only in debug mode)
 *
 * File output is optional. See \p LoggerOptions for setting this output stream.
 *
 * <b>Example of Logger usage:</b>
 *
 * For individual levels are defined macros -
 *  - MessageOut()
 *  - WarningOut()
 *  - LogOut()
 *  - DebugOut()
 * that ensure display of actual code point (source file, line and function).
 *
 * Logger message is created by using an operator << and allow to add each type
 * that has override this operator. Message is terminated with manipulator
 * std::endl. Implicitly logger message is printed only in processor with rank
 * zero. If necessary printed message for all process, it provides a method
 * every_proc().
 *
 * Examples of logger messages formating:
 *
 @code
   MessageOut() << "End of simulation at time: " << secondary_eq->solved_time() << "\n";
   WarningOut() << "Unprocessed key '" << key_name << "' in Record '" << rec->type_name() << "'." << "\n";
   LogOut() << "Write output to output stream: " << this->_base_filename << " for time: " << time << "\n";
   DebugOut() << "Calling 'initialize' of empty equation '" << typeid(*this).name() << "'." << "\n";
 @endcode
 *
 * Logger message can be created by more than one line ("\n" can be used multiple
 * times):
 *
 @code
   MessageOut() << "Start time: " << this->start_time() << "\n" << "End time: " << this->end_time() << "\n";
 @endcode
 *
 * Or Logger allow using fmtlib functionality for simpler formatting of message:
 *
 @code
   MessageOut() << fmt::format("Start time: {}\nEnd time: {}\n", this->start_time(), this->end_time());
   MessageOut().fmt("Start time: {}\nEnd time: {}\n", this->start_time(), this->end_time());
 @endcode
 *
 * In some cases message can be printed for all processes:
 *
 @code
   MessageOut().every_proc() << "Size distributed at process: " << distr->lsize() << "\n";
 @endcode
 *
 * Implementation of Logger does not support manipulator std::endl. Please, use "\n" instead.
 */
class Logger : public std::ostream {
public:
    /// Enum of types of Logger messages.
    enum MsgType {
        warning = 0,
        message = 1,
        log = 2,
        debug = 3,
        error = 4
    };

    /// Return string value of given MsgType in full or shorter format (e.g. "WARNING" of "Wrn")
    static const std::string msg_type_string(MsgType msg_type, bool full_format = true);

    /// Constructor.
    Logger(MsgType type);

    /// Stores values for printing out line number, function, etc
    Logger& set_context(const char* file_name, const char* function, const int line);

    /// Set flag every_process_ to true
    Logger& every_proc();

    /**
     * @brief Allow use functionality of fmtlib for formating message.
     *
     * See examples in description of Logger class.
     */
    template<class... T>
    Logger& fmt(T&&... t)
    {
        return *this << fmt::format(std::forward<T>(t)...);
    }

    /// Destructor.
    ~Logger();

    
private:
    /// Set @p streams_mask_ according to the type of message.
    void set_mask();

    /// Print formated message to given screen stream if mask corresponds with @p streams_mask_.
    void print_to_screen(std::ostream& stream, std::stringstream& scr_stream, StreamMask mask);

    /// Print formated message to given file stream if mask corresponds with @p streams_mask_.
    void print_to_file(std::ofstream& stream, std::stringstream& file_stream, StreamMask mask);

    /// Print header to screen stream, helper method called from \p print_to_screen.
    bool print_screen_header(std::ostream& stream, std::stringstream& scr_stream);

    /// Print header to file stream, helper method called from \p print_to_file.
    void print_file_header(std::ofstream& stream, std::stringstream& file_stream);

    std::stringstream cout_stream_;       ///< Store messages printed to cout output stream
    std::stringstream cerr_stream_;       ///< Store messages printed to cerr output stream
    std::stringstream file_stream_;       ///< Store messages printed to file

    MsgType type_;                        ///< Type of message.
    bool every_process_;                  ///< Flag marked if log message is printing for all processes or only for zero process.
    std::string file_name_;               ///< Actual file.
    std::string function_;                ///< Actual function.
    int line_;                            ///< Actual line.
    std::string date_time_;               ///< Actual date and time.
    int mpi_rank_;                        ///< Actual process (if MPI is supported)
    StreamMask streams_mask_;             ///< Mask of logger, specifies streams in actual time into which to be written
    StreamMask full_streams_mask_;        ///< Mask of logger, specifies all streams into which to be written in logger message

    template <class T>
    friend Logger &operator<<(Logger & log, const T & x);
    friend Logger &operator<<(Logger & log, std::ostream & (*pf) (std::ostream &) );
    friend Logger &operator<<(Logger & log, StreamMask mask);
};


Logger &operator<<(Logger & log, StreamMask mask);


Logger &operator<<(Logger & log, std::ostream & (*pf) (std::ostream &) );


template <class T>
Logger &operator<<(Logger & log, const T & x)
{
    if ( (log.streams_mask_ & StreamMask::cout)() ) log.cout_stream_ << x;
    if ( (log.streams_mask_ & StreamMask::cerr)() ) log.cerr_stream_ << x;
    if ( (log.streams_mask_ & StreamMask::log )() ) log.file_stream_ << x;
    return log;
}






/// Internal macro defining universal record of log
#define _LOG(type) \
    Logger( type ).set_context( __FILE__, __func__, __LINE__)
/// Macro defining 'message' record of log
#define MessageOut() \
    _LOG( Logger::MsgType::message )
/// Macro defining 'warning' record of log
#define WarningOut() \
    _LOG( Logger::MsgType::warning )
/// Macro defining 'log' record of log
#define LogOut() \
    _LOG( Logger::MsgType::log )
/// Macro defining 'debug' record of log
#define DebugOut() \
    _LOG( Logger::MsgType::debug )

/**
 * Print variable name and value.
 * Usage:
 * DebugOut() << print_var(x) << print_var(y)
 */
#define print_var(var) \
    std::string(#var) << "=" << (var) << ", "




#endif /* LOGGER_HH_ */