libstdc++-v3/libsupc++/typeinfo

   1 // RTTI support for -*- C++ -*-
   2 // Copyright (C) 1994, 1995, 1996, 1997, 1998, 2000, 2001 Free Software Foundation
   3 //
   4 // This file is part of GNU CC.
   5 //
   6 // GNU CC is free software; you can redistribute it and/or modify
   7 // it under the terms of the GNU General Public License as published by
   8 // the Free Software Foundation; either version 2, or (at your option)
   9 // any later version.
  10 //
  11 // GNU CC is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15 //
  16 // You should have received a copy of the GNU General Public License
  17 // along with GNU CC; see the file COPYING.  If not, write to
  18 // the Free Software Foundation, 59 Temple Place - Suite 330,
  19 // Boston, MA 02111-1307, USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30 /** @file typeinfo
  31  *  This header provides RTTI support.
  32  */
  33
  34 #ifndef __TYPEINFO__
  35 #define __TYPEINFO__
  36
  37 #include <exception>
  38
  39 extern "C++" {
  40
  41 namespace __cxxabiv1
  42 {
  43   class __class_type_info;
  44 } // namespace __cxxabiv1
  45
  46 #if !__GXX_WEAK__
  47   // If weak symbols are not supported, typeinfo names are not merged.
  48   #define __GXX_MERGED_TYPEINFO_NAMES 0
  49 #else
  50   // On platforms that support weak symbols, typeinfo names are merged.
  51   #define __GXX_MERGED_TYPEINFO_NAMES 1
  52 #endif
  53
  54 namespace std
  55 {
  56   /** The @c type_info class describes type information generated by
  57    *  an implementation.
  58    *  @brief Used in RTTI.  */
  59   class type_info
  60   {
  61   public:
  62     /** Destructor. Being the first non-inline virtual function, this
  63      *  controls in which translation unit the vtable is emitted. The
  64      *  compiler makes use of that information to know where to emit
  65      *  the runtime-mandated type_info structures in the new-abi.  */
  66     virtual ~type_info();
  67
  68   private:
  69     /// Assigning type_info is not supported.  Made private.
  70     type_info& operator=(const type_info&);
  71     type_info(const type_info&);
  72
  73   protected:
  74     const char *__name;
  75
  76   protected:
  77     explicit type_info(const char *__n): __name(__n) { }
  78
  79   public:
  80     // the public interface
  81     /** Returns an @e implementation-defined byte string; this is not
  82      *  portable between compilers!  */
  83     const char* name() const
  84     { return __name; }
  85
  86 #if !__GXX_MERGED_TYPEINFO_NAMES
  87     bool before(const type_info& arg) const;
  88     // In old abi, or when weak symbols are not supported, there can
  89     // be multiple instances of a type_info object for one
  90     // type. Uniqueness must use the _name value, not object address.
  91     bool operator==(const type_info& __arg) const;
  92 #else
  93     /** Returns true if @c *this preceeds @c __arg in the implementation's
  94      *  collation order.  */
  95     // In new abi we can rely on type_info's NTBS being unique,
  96     // and therefore address comparisons are sufficient.
  97     bool before(const type_info& __arg) const
  98     { return __name < __arg.__name; }
  99     bool operator==(const type_info& __arg) const
 100     { return __name == __arg.__name; }
 101 #endif
 102     bool operator!=(const type_info& __arg) const
 103     { return !operator==(__arg); }
 104
 105     // the internal interface
 106   public:
 107     // return true if this is a pointer type of some kind
 108     virtual bool __is_pointer_p() const;
 109     // return true if this is a function type
 110     virtual bool __is_function_p() const;
 111
 112     // Try and catch a thrown type. Store an adjusted pointer to the
 113     // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then
 114     // THR_OBJ points to the thrown object. If THR_TYPE is a pointer
 115     // type, then THR_OBJ is the pointer itself. OUTER indicates the
 116     // number of outer pointers, and whether they were const
 117     // qualified.
 118     virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj,
 119                             unsigned __outer) const;
 120
 121     // internally used during catch matching
 122     virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target,
 123                              void **__obj_ptr) const;
 124   };
 125
 126   /** If you attempt an invalid @c dynamic_cast expression, an instance of
 127    *  this class (or something derived from this class) is thrown.  */
 128   class bad_cast : public exception
 129   {
 130   public:
 131     bad_cast() throw() { }
 132     virtual ~bad_cast() throw();
 133   };
 134
 135   /** If you use a NULL pointer in a @c typeid expression, this is thrown.  */
 136   class bad_typeid : public exception
 137   {
 138   public:
 139     bad_typeid () throw() { }
 140     virtual ~bad_typeid () throw();
 141   };
 142 } // namespace std
 143
 144 } // extern "C++"
 145 #endif