libs/log/example/doc/expressions_attr_fmt_tag.cpp
/*
* Copyright Andrey Semashev 2007 - 2015.
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*/
#include <cstddef>
#include <iostream>
#include <boost/log/expressions.hpp>
#include <boost/log/sources/severity_logger.hpp>
#include <boost/log/sources/record_ostream.hpp>
#include <boost/log/utility/formatting_ostream.hpp>
#include <boost/log/utility/manipulators/to_log.hpp>
#include <boost/log/utility/setup/console.hpp>
#include <boost/log/utility/setup/common_attributes.hpp>
namespace logging = boost::log;
namespace src = boost::log::sources;
namespace expr = boost::log::expressions;
namespace keywords = boost::log::keywords;
//[ example_expressions_attr_formatter_stream_tag
// We define our own severity levels
enum severity_level
{
normal,
notification,
warning,
error,
critical
};
// The operator is used for regular stream formatting
std::ostream& operator<< (std::ostream& strm, severity_level level)
{
static const char* strings[] =
{
"normal",
"notification",
"warning",
"error",
"critical"
};
if (static_cast< std::size_t >(level) < sizeof(strings) / sizeof(*strings))
strm << strings[level];
else
strm << static_cast< int >(level);
return strm;
}
// Attribute value tag type
struct severity_tag;
// The operator is used when putting the severity level to log
logging::formatting_ostream& operator<<
(
logging::formatting_ostream& strm,
logging::to_log_manip< severity_level, severity_tag > const& manip
)
{
static const char* strings[] =
{
"NORM",
"NTFY",
"WARN",
"ERRR",
"CRIT"
};
severity_level level = manip.get();
if (static_cast< std::size_t >(level) < sizeof(strings) / sizeof(*strings))
strm << strings[level];
else
strm << static_cast< int >(level);
return strm;
}
void init()
{
logging::add_console_log
(
std::clog,
// This makes the sink to write log records that look like this:
// 1: <NORM> A normal severity message
// 2: <ERRR> An error severity message
keywords::format =
(
expr::stream
<< expr::attr< unsigned int >("LineID")
<< ": <" << expr::attr< severity_level, severity_tag >("Severity")
<< "> " << expr::smessage
)
);
}
//]
int main(int, char*[])
{
init();
logging::add_common_attributes();
src::severity_logger< severity_level > lg;
// These messages will be written with CAPS severity levels
BOOST_LOG_SEV(lg, normal) << "A normal severity message";
BOOST_LOG_SEV(lg, notification) << "A notification severity message";
BOOST_LOG_SEV(lg, warning) << "A warning severity message";
BOOST_LOG_SEV(lg, error) << "An error severity message";
BOOST_LOG_SEV(lg, critical) << "A critical severity message";
// This line will still use lower-case severity levels
std::cout << "The regular output still uses lower-case formatting: " << normal << std::endl;
return 0;
}