Abstract interface for a basic logging facility. More...

#include <ILogger.hxx>

Inheritance diagram for cosmos::ILogger:

Classes
struct	StreamState
	Internal state for each channel's stream. More...

Public Member Functions
std::ostream &	error ()
	Log an error message.

std::ostream &	warn ()
	Log a warning message.

std::ostream &	info ()
	Log an info message.

std::ostream &	debug ()
	Log a debug message.

void	setChannels (const bool error, const bool warning, const bool info, const bool debug)
	Enable/disable different log channels.

void	setPrefix (const std::string_view prefix)

Protected Member Functions
std::ostream &	getStream (StreamState &state)

std::ostream &	getNoopStream ()

void	setStreams (std::ostream &debug, std::ostream &info, std::ostream &warn, std::ostream &error)

void	setStream (std::ostream &s, StreamState &state)

Static Protected Member Functions
static bool	isTTY (const std::ostream &o)
	Returns whether the given ostream is associated with a terminal or not.

Protected Attributes
std::stringstream	m_null
	A noop stream object to write to if a channel is disabled.

StreamState	m_err

StreamState	m_warn

StreamState	m_info

StreamState	m_debug

std::string	m_common_prefix
	a common prefix to prepend to each message

Detailed Description

Abstract interface for a basic logging facility.

Applications can use this interface to log data to arbitrary places. You need to derive from this interface and decide what places these are.

The base class writes data to std::ostream instances. So an implementation of this class needs to provide some instance of std::ostream for writing to.

The logging supports four different categories for debug, info, warning and error messages.

This base class additionally provides means to write ANSI colored text if an ostream is associated with a terminal. Each category gets its own ANSI color. Each category can be directed to an individual output stream and be enabled/disabled individually.

By default all categories are enabled except debug.

Definition at line 32 of file ILogger.hxx.

Constructor & Destructor Documentation

◆ ~ILogger()

virtual cosmos::ILogger::~ILogger ( )

inlinevirtual

Definition at line 35 of file ILogger.hxx.

35{};

◆ ILogger()

cosmos::ILogger::ILogger ( )

protected

Definition at line 13 of file ILogger.cxx.

                 :
        m_err{  "Error:   ", FrontColor{TermColor::RED}},
        m_warn{ "Warning: ", FrontColor{TermColor::YELLOW}},
        m_info{ "Info:    ", FrontColor{TermColor::WHITE}},
        m_debug{"Debug:   ", FrontColor{TermColor::CYAN}}
{}

Member Function Documentation

◆ debug()

std::ostream & cosmos::ILogger::debug ( )

inline

Log a debug message.

Definition at line 44 of file ILogger.hxx.

44{ return getStream(m_debug); }

◆ error()

std::ostream & cosmos::ILogger::error ( )

inline

Log an error message.

Definition at line 38 of file ILogger.hxx.

38{ return getStream(m_err); }

◆ getNoopStream()

std::ostream & cosmos::ILogger::getNoopStream ( )

inlineprotected

Definition at line 92 of file ILogger.hxx.

                                    {
                // a real noop implementation of an ostream buffer will still
                // be cheaper than this, but at least it doesn't involve
                // system calls
                //
                // seek the start of the stringstream, to avoid the buffer
                // growing too much
                m_null.seekp(m_null.beg);
                return m_null;
        }

◆ getStream()

std::ostream & cosmos::ILogger::getStream ( StreamState & state )

inlineprotected

Definition at line 76 of file ILogger.hxx.

                                                  {
                auto &out = state.enabled ? *state.stream : getNoopStream();
 
                if (state.is_tty)
                        out << state.color;
 
                out << m_common_prefix;
 
                out << state.prefix;
 
                if (state.is_tty)
                        out << term::TermControl::DEFAULT_FG_COLOR;
 
                return out;
        }

◆ info()

std::ostream & cosmos::ILogger::info ( )

inline

Log an info message.

Definition at line 42 of file ILogger.hxx.

42{ return getStream(m_info); }

◆ isTTY()

bool cosmos::ILogger::isTTY ( const std::ostream & o )

staticprotected

Returns whether the given ostream is associated with a terminal or not.

Definition at line 20 of file ILogger.cxx.

                                       {
        /*
         * there's no elegant, portable way to get the file descriptor from an
         * ostream thus we have to use some heuristics ...
         */
 
        FileDescriptor fd_to_check;
 
        if (auto thisbuf = o.rdbuf(); thisbuf == std::cout.rdbuf()) {
                fd_to_check.setFD(FileNum::STDOUT);
        } else if (thisbuf == std::cerr.rdbuf()) {
                fd_to_check.setFD(FileNum::STDERR);
        } else {
                return false;
        }
 
        return Terminal{fd_to_check}.isTTY();
}

◆ setChannels()

void cosmos::ILogger::setChannels	(	const bool	error,
		const bool	warning,
		const bool	info,
		const bool	debug )

inline

Enable/disable different log channels.

Definition at line 47 of file ILogger.hxx.

                                                                                                  {
                m_err.enabled = error;
                m_warn.enabled = warning;
                m_info.enabled = info;
                m_debug.enabled = debug;
        }

◆ setPrefix()

void cosmos::ILogger::setPrefix ( const std::string_view prefix )

inline

Definition at line 54 of file ILogger.hxx.

                                                    {
                m_common_prefix = prefix;
        }

◆ setStream()

void cosmos::ILogger::setStream	(	std::ostream &	s,
		StreamState &	state )

protected

Definition at line 39 of file ILogger.cxx.

                                                         {
        state.stream = &s;
        state.is_tty = isTTY(s);
        state.enabled = (&state == &m_debug) ? false : true;
}

◆ setStreams()

void cosmos::ILogger::setStreams	(	std::ostream &	debug,
		std::ostream &	info,
		std::ostream &	warn,
		std::ostream &	error )

protected

Definition at line 45 of file ILogger.cxx.

                                                   {
        setStream(debug, m_debug);
        setStream(err, m_err);
        setStream(info, m_info);
        setStream(warn, m_warn);
}

◆ warn()

std::ostream & cosmos::ILogger::warn ( )

inline

Log a warning message.

Definition at line 40 of file ILogger.hxx.

40{ return getStream(m_warn); }

Member Data Documentation

◆ m_common_prefix

std::string cosmos::ILogger::m_common_prefix

protected

a common prefix to prepend to each message

Definition at line 124 of file ILogger.hxx.

◆ m_debug

StreamState cosmos::ILogger::m_debug

protected

Definition at line 122 of file ILogger.hxx.

◆ m_err

StreamState cosmos::ILogger::m_err

protected

Definition at line 119 of file ILogger.hxx.

◆ m_info

StreamState cosmos::ILogger::m_info

protected

Definition at line 121 of file ILogger.hxx.

◆ m_null

std::stringstream cosmos::ILogger::m_null

protected

A noop stream object to write to if a channel is disabled.

Definition at line 117 of file ILogger.hxx.

◆ m_warn

StreamState cosmos::ILogger::m_warn

protected

Definition at line 120 of file ILogger.hxx.

The documentation for this class was generated from the following files:

include/io/ILogger.hxx
src/io/ILogger.cxx

Classes

Public Member Functions

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ ~ILogger()

◆ ILogger()

Member Function Documentation

◆ debug()

◆ error()

◆ getNoopStream()

◆ getStream()

◆ info()

◆ isTTY()

◆ setChannels()

◆ setPrefix()

◆ setStream()

◆ setStreams()

◆ warn()

Member Data Documentation

◆ m_common_prefix

◆ m_debug

◆ m_err

◆ m_info

◆ m_null

◆ m_warn