libstdc++-v3/libsupc++/typeinfo

   1 // RTTI support for -*- C++ -*-
   2 // Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
   3 // 2003, 2004, 2005, 2006, 2007, 2009
   4 // Free Software Foundation
   5 //
   6 // This file is part of GCC.
   7 //
   8 // GCC is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3, or (at your option)
  11 // any later version.
  12 //
  13 // GCC is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17 //
  18 // Under Section 7 of GPL version 3, you are granted additional
  19 // permissions described in the GCC Runtime Library Exception, version
  20 // 3.1, as published by the Free Software Foundation.
  21
  22 // You should have received a copy of the GNU General Public License and
  23 // a copy of the GCC Runtime Library Exception along with this program;
  24 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  25 // <http://www.gnu.org/licenses/>.
  26
  27 /** @file typeinfo
  28  *  This is a Standard C++ Library header.
  29  */
  30
  31 #ifndef _TYPEINFO
  32 #define _TYPEINFO
  33
  34 #include <exception>
  35
  36 #pragma GCC visibility push(default)
  37
  38 extern "C++" {
  39
  40 namespace __cxxabiv1
  41 {
  42   class __class_type_info;
  43 } // namespace __cxxabiv1
  44
  45 // Determine whether typeinfo names for the same type are merged (in which
  46 // case comparison can just compare pointers) or not (in which case
  47 // strings must be compared and g++.dg/abi/local1.C will fail), and
  48 // whether comparison is to be implemented inline or not.  By default we
  49 // use inline pointer comparison if weak symbols are available, and
  50 // out-of-line strcmp if not.  Out-of-line pointer comparison is used
  51 // where the object files are to be portable to multiple systems, some of
  52 // which may not be able to use pointer comparison, but the particular
  53 // system for which libstdc++ is being built can use pointer comparison;
  54 // in particular for most ARM EABI systems, where the ABI specifies
  55 // out-of-line comparison.  Inline strcmp is not currently supported.  The
  56 // compiler's target configuration can override the defaults by defining
  57 // __GXX_TYPEINFO_EQUALITY_INLINE to 1 or 0 to indicate whether or not
  58 // comparison is inline, and __GXX_MERGED_TYPEINFO_NAMES to 1 or 0 to
  59 // indicate whether or not pointer comparison can be used.
  60
  61 #ifndef __GXX_MERGED_TYPEINFO_NAMES
  62   #if !__GXX_WEAK__
  63     // If weak symbols are not supported, typeinfo names are not merged.
  64     #define __GXX_MERGED_TYPEINFO_NAMES 0
  65   #else
  66     // On platforms that support weak symbols, typeinfo names are merged.
  67     #define __GXX_MERGED_TYPEINFO_NAMES 1
  68   #endif
  69 #endif
  70
  71 // By default follow the same rules as for __GXX_MERGED_TYPEINFO_NAMES.
  72 #ifndef __GXX_TYPEINFO_EQUALITY_INLINE
  73   #if !__GXX_WEAK__
  74     #define __GXX_TYPEINFO_EQUALITY_INLINE 0
  75   #else
  76     #define __GXX_TYPEINFO_EQUALITY_INLINE 1
  77   #endif
  78 #endif
  79
  80 namespace std
  81 {
  82   /**
  83    *  @brief  Part of RTTI.
  84    *
  85    *  The @c type_info class describes type information generated by
  86    *  an implementation.
  87   */
  88   class type_info
  89   {
  90   public:
  91     /** Destructor first. Being the first non-inline virtual function, this
  92      *  controls in which translation unit the vtable is emitted. The
  93      *  compiler makes use of that information to know where to emit
  94      *  the runtime-mandated type_info structures in the new-abi.  */
  95     virtual ~type_info();
  96
  97     /** Returns an @e implementation-defined byte string; this is not
  98      *  portable between compilers!  */
  99     const char* name() const
 100     { return __name; }
 101
 102 #if !__GXX_TYPEINFO_EQUALITY_INLINE
 103     bool before(const type_info& __arg) const;
 104
 105     // In old abi, or when weak symbols are not supported, there can
 106     // be multiple instances of a type_info object for one
 107     // type. Uniqueness must use the _name value, not object address.
 108     bool operator==(const type_info& __arg) const;
 109 #else
 110   #if !__GXX_MERGED_TYPEINFO_NAMES
 111     #error "Inline implementation of type_info comparision requires merging of type_info objects"
 112   #endif
 113     /** Returns true if @c *this precedes @c __arg in the implementation's
 114      *  collation order.  */
 115     // In new abi we can rely on type_info's NTBS being unique,
 116     // and therefore address comparisons are sufficient.
 117     bool before(const type_info& __arg) const
 118     { return __name < __arg.__name; }
 119
 120     bool operator==(const type_info& __arg) const
 121     { return __name == __arg.__name; }
 122 #endif
 123     bool operator!=(const type_info& __arg) const
 124     { return !operator==(__arg); }
 125
 126     // Return true if this is a pointer type of some kind
 127     virtual bool __is_pointer_p() const;
 128
 129     // Return true if this is a function type
 130     virtual bool __is_function_p() const;
 131
 132     // Try and catch a thrown type. Store an adjusted pointer to the
 133     // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then
 134     // THR_OBJ points to the thrown object. If THR_TYPE is a pointer
 135     // type, then THR_OBJ is the pointer itself. OUTER indicates the
 136     // number of outer pointers, and whether they were const
 137     // qualified.
 138     virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj,
 139                             unsigned __outer) const;
 140
 141     // Internally used during catch matching
 142     virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target,
 143                              void **__obj_ptr) const;
 144
 145   protected:
 146     const char *__name;
 147
 148     explicit type_info(const char *__n): __name(__n) { }
 149
 150   private:
 151     /// Assigning type_info is not supported.
 152     type_info& operator=(const type_info&);
 153     type_info(const type_info&);
 154   };
 155
 156   /**
 157    *  @brief  Thrown during incorrect typecasting.
 158    *  @ingroup exceptions
 159    *
 160    *  If you attempt an invalid @c dynamic_cast expression, an instance of
 161    *  this class (or something derived from this class) is thrown.  */
 162   class bad_cast : public exception
 163   {
 164   public:
 165     bad_cast() throw() { }
 166
 167     // This declaration is not useless:
 168     // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
 169     virtual ~bad_cast() throw();
 170
 171     // See comment in eh_exception.cc.
 172     virtual const char* what() const throw();
 173   };
 174
 175   /**
 176    *  @brief Thrown when a NULL pointer in a @c typeid expression is used.
 177    *  @ingroup exceptions
 178    */
 179   class bad_typeid : public exception
 180   {
 181   public:
 182     bad_typeid () throw() { }
 183
 184     // This declaration is not useless:
 185     // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
 186     virtual ~bad_typeid() throw();
 187
 188     // See comment in eh_exception.cc.
 189     virtual const char* what() const throw();
 190   };
 191 } // namespace std
 192
 193 #pragma GCC visibility pop
 194
 195 } // extern "C++"
 196 #endif