Dogcows Code - chaz/yoink/blob - src/moof/log.hh

   1
   2 /*]  Copyright (c) 2009-2011, Charles McGarvey  [*****************************
   3 **]  All rights reserved.
   4 *
   5 * Distributable under the terms and conditions of the 2-clause BSD license;
   6 * see the file COPYING for a complete text of the license.
   7 *
   8 *****************************************************************************/
   9
  10 #ifndef _MOOF_LOG_HH_
  11 #define _MOOF_LOG_HH_
  12
  13 /**
  14  * \file log.hh
  15  * Functions related to logging the process.  The logging functions are
  16  * log_error(), log_warning(), and log_info(), listed from most critical to
  17  * least critical.
  18  */
  19
  20 #include <cstdlib>              // exit
  21 #include <iostream>
  22 #include <string>
  23
  24
  25 namespace moof {
  26
  27
  28 // forward declarations
  29 class script;
  30
  31 /**
  32  * A class for handling a log priority.  There are two ways to log
  33  * messages: by treating a log object as a function whose parameters are
  34  * printed with default spacing, or by treating a log object as an output
  35  * stream.  Either way, any object can be printed to the log as long as
  36  * there is an override for the ostream insertion operator.
  37  */
  38 class log
  39 {
  40 public:
  41
  42         /**
  43          * A type for the level or priority of a log message.
  44          */
  45         enum level
  46         {
  47                 none            = 0,    ///< Disable all logging.
  48                 error           = 1,    ///< Log only errors.
  49                 warning         = 2,    ///< Log warnings and errors.
  50                 info            = 3,    ///< Log everything.
  51                 debug           = 4,    ///< Log absolutely everything.
  52         };
  53
  54         /**
  55          * Set the lowest-priority log message that will be outputted to the
  56          * log.  Any logging with a lower priority will be ignored.
  57          * \param level The log level.
  58          */
  59         static void level(level level);
  60
  61         /**
  62          * Get the current lowest-priority log level.  If unchanged, the
  63          * default level is info.
  64          * \return The log level.
  65          */
  66         static enum level level();
  67
  68         /**
  69          * Import log functions to a script.
  70          * \param The script.
  71          */
  72         static void import(script& script);
  73
  74         /**
  75          * Construct a log with a certain priority and prefix string.
  76          * \param level The log level.
  77          * \param prefix The string printed before each log message.
  78          */
  79         log(enum level level);
  80
  81         /**
  82          * Output this to end a line.  This is equivalent to std::endl except
  83          * this will also reset terminal format attributes.
  84          */
  85         static struct endl_
  86         {
  87         } endl;
  88
  89         template <class A>
  90         void operator () (const A& a)
  91         {
  92                 *this << a << endl;
  93         }
  94
  95         template <class A, class B>
  96         void operator () (const A& a, const B& b)
  97         {
  98                 *this << a << " " << b << endl;
  99         }
 100
 101         template <class A, class B, class C>
 102         void operator () (const A& a, const B& b, const C& c)
 103         {
 104                 *this << a << " " << b << " " << c << endl;
 105         }
 106
 107         template <class A, class B, class C, class D>
 108         void operator () (const A& a, const B& b, const C& c, const D& d)
 109         {
 110                 *this << a << " " << b << " " << c << " " << d << endl;
 111         }
 112
 113         template <class A, class B, class C, class D, class E>
 114         void operator () (const A& a,
 115                         const B& b,
 116                         const C& c,
 117                         const D& d,
 118                         const E& e)
 119         {
 120                 *this << a << " " << b << " " << c << " " << d << " " << e <<
 121                         endl;
 122         }
 123
 124 private:
 125
 126         template <class T> friend std::ostream& operator << (log&, const T&);
 127         friend std::ostream& operator << (log&, endl_);
 128
 129         static enum level       global_level_;
 130
 131         enum level              level_;
 132         std::string             prefix_;
 133 };
 134
 135 extern std::ostream&    log;
 136 extern std::ostream&    null_log;
 137
 138 extern class log& log_error;
 139 extern class log& log_warning;
 140 extern class log& log_info;
 141 extern class log& log_debug;
 142
 143
 144 template <class T>
 145 inline std::ostream& operator << (class log& log, const T& item)
 146 {
 147         if (log::global_level_ < log.level_) return null_log;
 148         return moof::log << log.prefix_ << item;
 149 }
 150
 151 std::ostream& operator << (class log& log, log::endl_ endl);
 152 std::ostream& operator << (std::ostream& stream, log::endl_ endl);
 153
 154
 155 } // namespace moof
 156
 157 #endif // _MOOF_LOG_HH_
 158