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/*
* Copyright Andrey Semashev 2025.
* 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 <cstdint>
#include <iostream>
#include <boost/log/expressions.hpp>
#include <boost/log/attributes/constant.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/value_ref.hpp>
#include <boost/log/utility/setup/console.hpp>
#include <boost/log/utility/setup/common_attributes.hpp>
namespace logging = boost::log;
namespace attrs = boost::log::attributes;
namespace src = boost::log::sources;
namespace expr = boost::log::expressions;
namespace keywords = boost::log::keywords;
enum severity_level
{
normal,
notification,
warning,
error,
critical
};
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;
}
//[ example_expressions_wrap_formatter
// Define a custom attribute value type
struct host_address
{
std::string hostname;
std::uint_least16_t port = 0;
};
// Define the attribute keywords
BOOST_LOG_ATTRIBUTE_KEYWORD(severity, "Severity", severity_level)
BOOST_LOG_ATTRIBUTE_KEYWORD(host, "Host", host_address)
// User-defined formatter for the Host attribute values
void format_host(logging::record_view const& rec, logging::formatting_ostream& stream)
{
// Formatter implementation outputs directly into the formatting stream
logging::value_ref< host_address, tag::host > host_ref = rec[host];
if (host_ref)
{
stream << host_ref->hostname;
if (host_ref->port != 0)
stream << ":" << host_ref->port;
}
else
{
stream << "-";
}
}
void init()
{
logging::add_console_log
(
std::clog,
keywords::format =
expr::stream << "<" << severity << "> ["
<< expr::wrap_formatter< char >(&format_host)
<< "] " << expr::smessage
);
}
//]
int main(int, char*[])
{
init();
logging::add_common_attributes();
src::severity_logger< severity_level > lg1;
host_address h;
h.hostname = "hostname";
h.port = 1234;
lg1.add_attribute(host.get_name(), attrs::make_constant(h));
BOOST_LOG_SEV(lg1, normal) << "Connection established";
BOOST_LOG_SEV(lg1, normal) << "Connection closed";
src::severity_logger< severity_level > lg2;
BOOST_LOG_SEV(lg2, normal) << "Message not associated with a host";
return 0;
}
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