xbmc/commons/Exception.h

   1 /*
   2  *  Copyright (C) 2005-2018 Team Kodi
   3  *  This file is part of Kodi - https://kodi.tv
   4  *
   5  *  SPDX-License-Identifier: GPL-2.0-or-later
   6  *  See LICENSES/README.md for more information.
   7  */
   8
   9 #pragma once
  10
  11 //---------------------------------------------------------
  12 // This include should be moved to commons but even as it is,
  13 // it wont cause a linker circular dependency since it's just
  14 // a header.
  15 #include "utils/StringUtils.h"
  16 //---------------------------------------------------------
  17 #include <stdarg.h>
  18
  19
  20 #ifdef __GNUC__
  21 // The 'this' pointer counts as a parameter on member methods.
  22 #define XBMCCOMMONS_ATTRIB_EXCEPTION_FORMAT __attribute__((format(printf,2,3)))
  23 #else
  24 #define XBMCCOMMONS_ATTRIB_EXCEPTION_FORMAT
  25 #endif
  26
  27 #define XBMCCOMMONS_COPYVARARGS(fmt) va_list argList; va_start(argList, fmt); Set(fmt, argList); va_end(argList)
  28 #define XBMCCOMMONS_STANDARD_EXCEPTION(E) \
  29   class E : public XbmcCommons::Exception \
  30   { \
  31   public: \
  32     inline E(const char* message,...) XBMCCOMMONS_ATTRIB_EXCEPTION_FORMAT : Exception(#E) { XBMCCOMMONS_COPYVARARGS(message); } \
  33     \
  34     inline E(const E& other) : Exception(other) {} \
  35   }
  36
  37 namespace XbmcCommons
  38 {
  39   /**
  40    * This class a superclass for exceptions that want to utilize some
  41    * utility functionality including autologging with the specific
  42    * exception name.
  43    */
  44   class Exception
  45   {
  46   private:
  47
  48     std::string classname;
  49     std::string message;
  50
  51   protected:
  52
  53     inline explicit Exception(const char* classname_) : classname(classname_) { }
  54     inline Exception(const char* classname_, const char* message_) : classname(classname_), message(message_) { }
  55     inline Exception(const Exception& other) = default;
  56
  57     /**
  58      * This method is called from the constructor of subclasses. It
  59      * will set the message from varargs as well as call log message
  60      */
  61     inline void Set(const char* fmt, va_list& argList)
  62     {
  63       message = StringUtils::FormatV(fmt, argList);
  64     }
  65
  66     /**
  67      * This message can be called from the constructor of subclasses.
  68      * It will set the message and log the throwing.
  69      */
  70     inline void SetMessage(const char* fmt, ...) XBMCCOMMONS_ATTRIB_EXCEPTION_FORMAT
  71     {
  72       // calls 'set'
  73       XBMCCOMMONS_COPYVARARGS(fmt);
  74     }
  75
  76     inline void setClassname(const char* cn) { classname = cn; }
  77
  78   public:
  79     virtual ~Exception();
  80
  81     virtual void LogThrowMessage(const char* prefix = NULL) const;
  82
  83     inline virtual const char* GetExMessage() const { return message.c_str(); }
  84   };
  85
  86   /**
  87    * This class forms the base class for unchecked exceptions. Unchecked exceptions
  88    * are those that really shouldn't be handled explicitly. For example, on windows
  89    * when a access violation is converted to a win32_exception, there's nothing
  90    * that can be done in most code. The outer most stack frame might try to
  91    * do some error logging prior to shutting down, but that's really it.
  92    */
  93   XBMCCOMMONS_STANDARD_EXCEPTION(UncheckedException);
  94
  95 /**
  96  * In cases where you catch(...){} you will (may) inadvertently be
  97  * catching UncheckedException's. Therefore this macro will allow
  98  * you to do something equivalent to:
  99  *    catch (anything except UncheckedException) {}
 100  *
 101  * In order to avoid catching UncheckedException, use the macro as follows:
 102  *
 103  *    try { ... }
 104  *    XBMCCOMMONS_HANDLE_UNCHECKED
 105  *    catch(...){ ... }
 106  */
 107 // Yes. I recognize that the name of this macro is an oxymoron.
 108 #define  XBMCCOMMONS_HANDLE_UNCHECKED \
 109   catch (const XbmcCommons::UncheckedException& ) { throw; } \
 110   catch (const XbmcCommons::UncheckedException* ) { throw; }
 111
 112 }
 113