source/ps/Errors.h

   1 /* Copyright (C) 2013 Wildfire Games.
   2  * This file is part of 0 A.D.
   3  *
   4  * 0 A.D. is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * 0 A.D. is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #ifndef INCLUDED_ERRORS
  19 #define INCLUDED_ERRORS
  20
  21 /*
  22
  23 The overly-complex error system works as follows:
  24
  25 A source file (typically a .h) can declare errors as follows:
  26
  27         ERROR_GROUP(ModuleName);
  28         ERROR_TYPE(ModuleName, FrobnificationFailed);
  29         ERROR_SUBGROUP(ModuleName, ComponentName);
  30         ERROR_TYPE(ModuleName_ComponentName, FileNotFound);
  31
  32 etc, to build up a hierarchy of error types.
  33
  34 Then you have to run the /build/errorlist/errorlist.pl script, to regenerate
  35 the Errors.cpp file.
  36
  37 Then you can use the declared errors as an error code:
  38
  39         PSRETURN foo() { return PSRETURN_ModuleName_FrobnificationFailed; }
  40
  41         if (ret != PSRETURN_OK)
  42                 ... // something failed
  43
  44         if (ret)
  45                 ... // something failed
  46
  47         if (ret == PSRETURN_ModuleName_FrobnificationFailed)
  48                 ... // particular error
  49
  50         if (ERROR_IS(ret, PSRETURN_ModuleName))
  51                 ... // matches any type PSRETURN_ModuleName_* (and PSRETURN_ModuleName_*_* etc)
  52
  53 And you can use it as an exception:
  54
  55         void foo() { throw PSERROR_ModuleName_FrobnificationFailed(); }
  56
  57         void bar() { throw PSERROR_ModuleName_FrobnificationFailed("More informative message"); }
  58
  59         try {
  60                 foo();
  61         } catch (PSERROR_ModuleName_FrobnificationFailed& e) {
  62                 // catches that particular error type
  63         } catch (PSERROR_ModuleName& e) {
  64                 // catches anything in the hierarchy
  65         } catch (PSERROR& e) {
  66                 std::cout << e.what();
  67         }
  68
  69 plus a few extra things for converting between error codes and exceptions.
  70
  71 */
  72
  73 #include <exception>
  74
  75 typedef u32 PSRETURN;
  76
  77 class PSERROR : public std::exception
  78 {
  79 public:
  80         PSERROR(const char* msg);
  81         virtual const char* what() const throw ();
  82         virtual PSRETURN getCode() const = 0; // for functions that catch exceptions then return error codes
  83 private:
  84         const char* m_msg;
  85 };
  86
  87 #define ERROR_GROUP(a) class PSERROR_##a : public PSERROR { protected: PSERROR_##a(const char* msg); }; \
  88                                                 extern const PSRETURN MASK__PSRETURN_##a; \
  89                                                 extern const PSRETURN CODE__PSRETURN_##a
  90
  91 #define ERROR_SUBGROUP(a,b) class PSERROR_##a##_##b : public PSERROR_##a { protected: PSERROR_##a##_##b(const char* msg); }; \
  92                                                 extern const PSRETURN MASK__PSRETURN_##a##_##b; \
  93                                                 extern const PSRETURN CODE__PSRETURN_##a##_##b
  94
  95
  96 #define ERROR_TYPE(a,b) class PSERROR_##a##_##b : public PSERROR_##a { public: PSERROR_##a##_##b(); PSERROR_##a##_##b(const char* msg); PSRETURN getCode() const; }; \
  97                                                 extern const PSRETURN MASK__PSRETURN_##a##_##b; \
  98                                                 extern const PSRETURN CODE__PSRETURN_##a##_##b; \
  99                                                 extern const PSRETURN PSRETURN_##a##_##b
 100
 101 #define ERROR_IS(a, b) ( ((a) & MASK__PSRETURN_##b) == CODE__PSRETURN_##b )
 102
 103 const PSRETURN PSRETURN_OK = 0;
 104 const PSRETURN MASK__PSRETURN_OK = 0xFFFFFFFF;
 105 const PSRETURN CODE__PSRETURN_OK = 0;
 106
 107 const char* GetErrorString(PSRETURN code);
 108 void ThrowError(PSRETURN code);
 109
 110 #endif