libstdc++-v3/libsupc++/typeinfo

   1 // RTTI support for -*- C++ -*-
   2 // Copyright (C) 1994, 1995, 1996, 1997, 1998, 2000, 2001, 2002
   3 // Free Software Foundation
   4 //
   5 // This file is part of GCC.
   6 //
   7 // GCC is free software; you can redistribute it and/or modify
   8 // it under the terms of the GNU General Public License as published by
   9 // the Free Software Foundation; either version 2, or (at your option)
  10 // any later version.
  11 //
  12 // GCC is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16 //
  17 // You should have received a copy of the GNU General Public License
  18 // along with GCC; see the file COPYING.  If not, write to
  19 // the Free Software Foundation, 59 Temple Place - Suite 330,
  20 // Boston, MA 02111-1307, USA.
  21
  22 // As a special exception, you may use this file as part of a free software
  23 // library without restriction.  Specifically, if other files instantiate
  24 // templates or use macros or inline functions from this file, or you compile
  25 // this file and link it with other files to produce an executable, this
  26 // file does not by itself cause the resulting executable to be covered by
  27 // the GNU General Public License.  This exception does not however
  28 // invalidate any other reasons why the executable file might be covered by
  29 // the GNU General Public License.
  30
  31 /** @file typeinfo
  32  *  This header provides RTTI support.
  33  */
  34
  35 #ifndef _TYPEINFO
  36 #define _TYPEINFO
  37
  38 #include <exception>
  39
  40 extern "C++" {
  41
  42 namespace __cxxabiv1
  43 {
  44   class __class_type_info;
  45 } // namespace __cxxabiv1
  46
  47 #if !__GXX_WEAK__
  48   // If weak symbols are not supported, typeinfo names are not merged.
  49   #define __GXX_MERGED_TYPEINFO_NAMES 0
  50 #else
  51   // On platforms that support weak symbols, typeinfo names are merged.
  52   #define __GXX_MERGED_TYPEINFO_NAMES 1
  53 #endif
  54
  55 namespace std
  56 {
  57   /**
  58    *  @brief  Part of RTTI.
  59    *
  60    *  The @c type_info class describes type information generated by
  61    *  an implementation.
  62   */
  63   class type_info
  64   {
  65   public:
  66     /** Destructor. Being the first non-inline virtual function, this
  67      *  controls in which translation unit the vtable is emitted. The
  68      *  compiler makes use of that information to know where to emit
  69      *  the runtime-mandated type_info structures in the new-abi.  */
  70     virtual ~type_info();
  71
  72   private:
  73     /// Assigning type_info is not supported.  Made private.
  74     type_info& operator=(const type_info&);
  75     type_info(const type_info&);
  76
  77   protected:
  78     const char *__name;
  79
  80   protected:
  81     explicit type_info(const char *__n): __name(__n) { }
  82
  83   public:
  84     // the public interface
  85     /** Returns an @e implementation-defined byte string; this is not
  86      *  portable between compilers!  */
  87     const char* name() const
  88     { return __name; }
  89
  90 #if !__GXX_MERGED_TYPEINFO_NAMES
  91     bool before(const type_info& __arg) const;
  92     // In old abi, or when weak symbols are not supported, there can
  93     // be multiple instances of a type_info object for one
  94     // type. Uniqueness must use the _name value, not object address.
  95     bool operator==(const type_info& __arg) const;
  96 #else
  97     /** Returns true if @c *this precedes @c __arg in the implementation's
  98      *  collation order.  */
  99     // In new abi we can rely on type_info's NTBS being unique,
 100     // and therefore address comparisons are sufficient.
 101     bool before(const type_info& __arg) const
 102     { return __name < __arg.__name; }
 103     bool operator==(const type_info& __arg) const
 104     { return __name == __arg.__name; }
 105 #endif
 106     bool operator!=(const type_info& __arg) const
 107     { return !operator==(__arg); }
 108
 109     // the internal interface
 110   public:
 111     // return true if this is a pointer type of some kind
 112     virtual bool __is_pointer_p() const;
 113     // return true if this is a function type
 114     virtual bool __is_function_p() const;
 115
 116     // Try and catch a thrown type. Store an adjusted pointer to the
 117     // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then
 118     // THR_OBJ points to the thrown object. If THR_TYPE is a pointer
 119     // type, then THR_OBJ is the pointer itself. OUTER indicates the
 120     // number of outer pointers, and whether they were const
 121     // qualified.
 122     virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj,
 123                             unsigned __outer) const;
 124
 125     // internally used during catch matching
 126     virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target,
 127                              void **__obj_ptr) const;
 128   };
 129
 130   /**
 131    *  @brief  Thrown during incorrect typecasting.
 132    *
 133    *  If you attempt an invalid @c dynamic_cast expression, an instance of
 134    *  this class (or something derived from this class) is thrown.  */
 135   class bad_cast : public exception
 136   {
 137   public:
 138     bad_cast() throw() { }
 139     // This declaration is not useless:
 140     // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
 141     virtual ~bad_cast() throw();
 142   };
 143
 144   /** If you use a NULL pointer in a @c typeid expression, this is thrown.  */
 145   class bad_typeid : public exception
 146   {
 147   public:
 148     bad_typeid () throw() { }
 149     // This declaration is not useless:
 150     // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
 151     virtual ~bad_typeid() throw();
 152   };
 153 } // namespace std
 154
 155 } // extern "C++"
 156 #endif