ceph/src/boost/libs/log/example/doc/expressions_keyword_fmt_tag.cpp

   1 /*
   2  *          Copyright Andrey Semashev 2007 - 2015.
   3  * Distributed under the Boost Software License, Version 1.0.
   4  *    (See accompanying file LICENSE_1_0.txt or copy at
   5  *          http://www.boost.org/LICENSE_1_0.txt)
   6  */
   7
   8 #include <cstddef>
   9 #include <iostream>
  10 #include <boost/log/expressions.hpp>
  11 #include <boost/log/sources/severity_logger.hpp>
  12 #include <boost/log/sources/record_ostream.hpp>
  13 #include <boost/log/utility/formatting_ostream.hpp>
  14 #include <boost/log/utility/manipulators/to_log.hpp>
  15 #include <boost/log/utility/setup/console.hpp>
  16 #include <boost/log/utility/setup/common_attributes.hpp>
  17
  18 namespace logging = boost::log;
  19 namespace src = boost::log::sources;
  20 namespace expr = boost::log::expressions;
  21 namespace keywords = boost::log::keywords;
  22
  23 //[ example_expressions_keyword_formatter_stream_tag
  24 // We define our own severity levels
  25 enum severity_level
  26 {
  27     normal,
  28     notification,
  29     warning,
  30     error,
  31     critical
  32 };
  33
  34 // Define the attribute keywords
  35 BOOST_LOG_ATTRIBUTE_KEYWORD(line_id, "LineID", unsigned int)
  36 BOOST_LOG_ATTRIBUTE_KEYWORD(severity, "Severity", severity_level)
  37
  38 // The operator is used for regular stream formatting
  39 std::ostream& operator<< (std::ostream& strm, severity_level level)
  40 {
  41     static const char* strings[] =
  42     {
  43         "normal",
  44         "notification",
  45         "warning",
  46         "error",
  47         "critical"
  48     };
  49
  50     if (static_cast< std::size_t >(level) < sizeof(strings) / sizeof(*strings))
  51         strm << strings[level];
  52     else
  53         strm << static_cast< int >(level);
  54
  55     return strm;
  56 }
  57
  58 // The operator is used when putting the severity level to log
  59 logging::formatting_ostream& operator<<
  60 (
  61     logging::formatting_ostream& strm,
  62     logging::to_log_manip< severity_level, tag::severity > const& manip
  63 )
  64 {
  65     static const char* strings[] =
  66     {
  67         "NORM",
  68         "NTFY",
  69         "WARN",
  70         "ERRR",
  71         "CRIT"
  72     };
  73
  74     severity_level level = manip.get();
  75     if (static_cast< std::size_t >(level) < sizeof(strings) / sizeof(*strings))
  76         strm << strings[level];
  77     else
  78         strm << static_cast< int >(level);
  79
  80     return strm;
  81 }
  82
  83 void init()
  84 {
  85     logging::add_console_log
  86     (
  87         std::clog,
  88         // This makes the sink to write log records that look like this:
  89         // 1: <NORM> A normal severity message
  90         // 2: <ERRR> An error severity message
  91         keywords::format =
  92         (
  93             expr::stream
  94                 << line_id
  95                 << ": <" << severity
  96                 << "> " << expr::smessage
  97         )
  98     );
  99 }
 100 //]
 101
 102 //[ example_expressions_keyword_lookup
 103 void print_severity(logging::record_view const& rec)
 104 {
 105     logging::value_ref< severity_level, tag::severity > level = rec[severity];
 106     std::cout << level << std::endl;
 107 }
 108 //]
 109
 110
 111 int main(int, char*[])
 112 {
 113     init();
 114     logging::add_common_attributes();
 115
 116     src::severity_logger< severity_level > lg;
 117
 118     // These messages will be written with CAPS severity levels
 119     BOOST_LOG_SEV(lg, normal) << "A normal severity message";
 120     BOOST_LOG_SEV(lg, notification) << "A notification severity message";
 121     BOOST_LOG_SEV(lg, warning) << "A warning severity message";
 122     BOOST_LOG_SEV(lg, error) << "An error severity message";
 123     BOOST_LOG_SEV(lg, critical) << "A critical severity message";
 124
 125     // This line will still use lower-case severity levels
 126     std::cout << "The regular output still uses lower-case formatting: " << normal << std::endl;
 127
 128     return 0;
 129 }