日志对于一个系统来说确实是必不可少的基础模块。
我用模板写了个不依赖于具体‘写’的日志类，简单的日志等级过滤。
///
/// @file kl_logger.h
/// @author Kevin Lynx
/// @date 4.21.2008
///
#ifndef ___KL_LOGGER_H_
#define ___KL_LOGGER_H_
#include <assert.h>
#include <stdarg.h>
#include <time.h>
#include <fstream>
#include "kl_compiler_cfg.h"
KL_COMMON_NAMESPACE_BEGIN
/// log level
enum log_level
{
LL_MIN = -1,
LL_ERROR,
LL_WARNING,
LL_INFO,
LL_DEBUG,
LL_MAX
};
///
/// default log pre-string, add system time and log level.
///
struct default_log_prestr
{
/// output pre-string in the buffer
/// @return the offset of the buf.
std::size_t operator() ( char *buf, int level )
{
char time[9];
char date[9];
_strtime( time );
_strdate( date );
const char *ll_desc = 0;
switch( level )
{
case LL_ERROR:
ll_desc = "ERROR";
break;
case LL_WARNING:
ll_desc = "WARNING";
break;
case LL_INFO:
ll_desc = "INFO";
break;
case LL_DEBUG:
ll_desc = "DEBUG";
break;
default:
ll_desc = "UNKNOWN";
}
// combine
sprintf( buf, "%s %s %s : ", date, time, ll_desc );
return strlen( buf ) ;
}
};
///
///
/// A simple logger class to write log information.
///
/// @param _Output where the log information to put, it must implement 'log( const char*)' function.
/// @param _PreStr used to write the pre-string of the log text like : 4.21.2008 : something.
/// @param string_size used when format string.(static buffer is more fast than dynamic buffer)
template <typename _Output, typename _PreStr = default_log_prestr, std::size_t _string_size = 1024>
class logger
{
public:
/// output object type
typedef _Output output_type;
/// pre-string type
typedef _PreStr prestr_type;
/// string size used when formatting strings.
enum
{
string_size = _string_size
};
public:
/// constructor
logger() :
_output( 0 ), _level( LL_DEBUG )
{
}
/// destructor
~logger()
{
}
/// set the output manager, you must call this function before you
/// log anything.
void set_output( output_type *ot )
{
assert( ot != 0 && "logger::set_output : invalid arguments." );
_output = ot;
}
/// write log text
void write_only( int level, const char *format, ... )
{
assert( _output != 0 && "logger::write_only : You must set up the output manager before you log anything." );
static char buf[string_size];
// checck the level
if( level > _level ) return ;
// format the string
va_list list;
va_start( list, format );
vsprintf( buf, format, list );
va_end( list );
// output the log text
_output->log( buf );
}
/// write log text and append prestring
void write( int level, const char *format, ... )
{
assert( _output != 0 && "logger::write : You must set up the output manager before you log anything." );
static char buf[string_size];
// checck the level
if( level > _level ) return ;
// append pre-string
std::size_t pos = _prestr( buf, level );
// format the string
va_list list;
va_start( list, format );
vsprintf( &buf[pos], format, list );
va_end( list );
// output the log text
_output->log( buf );
}
/// set log level
void set_level( int level )
{
assert( level > LL_MIN && level < LL_MAX && "logger::set_level : invalid arguments." );
_level = level;
}
/// get the log level
int get_level()
{
return _level;
}
private:
/// output manager to collect log text.
output_type *_output;
/// pre-str to append some text before the log text
prestr_type _prestr;
/// log level
int _level;
};
///
/// The file log output manager, write log text to the file.
///
class file_output
{
public:
/// constructor
file_output()
{
}
/// this constructor will open the file
file_output( const std::string filename, std::ios_base::openmode _Mode = std::ios_base::out ) :
_file_handle( filename.c_str(), _Mode )
{
}
/// destructor
~file_output()
{
}
/// open the file if it's not open
bool open( const std::string filename, std::ios_base::openmode _Mode = std::ios_base::out )
{
if( _file_handle.is_open() )
{
return false;
}
_file_handle.open( filename.c_str(), _Mode );
return _file_handle.is_open();
}
/// log
void log( const char *str )
{
assert( _file_handle.is_open() && "file_output::log : you cannot write anything before you open the file!" );
_file_handle << str ;
_file_handle.flush();
}
private:
/// output file
std::ofstream _file_handle;
};
KL_COMMON_NAMESPACE_END
#endif // end ___KL_LOGGER_H_