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
   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 2, 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 // You should have received a copy of the GNU General Public License
  19 // along with GCC; see the file COPYING.  If not, write to
  20 // the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  21 // Boston, MA 02110-1301, USA.
  22
  23 // As a special exception, you may use this file as part of a free software
  24 // library without restriction.  Specifically, if other files instantiate
  25 // templates or use macros or inline functions from this file, or you compile
  26 // this file and link it with other files to produce an executable, this
  27 // file does not by itself cause the resulting executable to be covered by
  28 // the GNU General Public License.  This exception does not however
  29 // invalidate any other reasons why the executable file might be covered by
  30 // the GNU General Public License.
  31
  32 /** @file typeinfo
  33  *  This is a Standard C++ Library header.
  34  */
  35
  36 #ifndef _TYPEINFO
  37 #define _TYPEINFO
  38
  39 #include <exception>
  40
  41 #pragma GCC visibility push(default)
  42
  43 extern "C++" {
  44
  45 namespace __cxxabiv1
  46 {
  47   class __class_type_info;
  48 } // namespace __cxxabiv1
  49
  50 // Determine whether typeinfo names for the same type are merged (in which
  51 // case comparison can just compare pointers) or not (in which case
  52 // strings must be compared and g++.dg/abi/local1.C will fail), and
  53 // whether comparison is to be implemented inline or not.  By default we
  54 // use inline pointer comparison if weak symbols are available, and
  55 // out-of-line strcmp if not.  Out-of-line pointer comparison is used
  56 // where the object files are to be portable to multiple systems, some of
  57 // which may not be able to use pointer comparison, but the particular
  58 // system for which libstdc++ is being built can use pointer comparison;
  59 // in particular for most ARM EABI systems, where the ABI specifies
  60 // out-of-line comparison.  Inline strcmp is not currently supported.  The
  61 // compiler's target configuration can override the defaults by defining
  62 // __GXX_TYPEINFO_EQUALITY_INLINE to 1 or 0 to indicate whether or not
  63 // comparison is inline, and __GXX_MERGED_TYPEINFO_NAMES to 1 or 0 to
  64 // indicate whether or not pointer comparison can be used.
  65
  66 #ifndef __GXX_MERGED_TYPEINFO_NAMES
  67   #if !__GXX_WEAK__
  68     // If weak symbols are not supported, typeinfo names are not merged.
  69     #define __GXX_MERGED_TYPEINFO_NAMES 0
  70   #else
  71     // On platforms that support weak symbols, typeinfo names are merged.
  72     #define __GXX_MERGED_TYPEINFO_NAMES 1
  73   #endif
  74 #endif
  75
  76 // By default follow the same rules as for __GXX_MERGED_TYPEINFO_NAMES.
  77 #ifndef __GXX_TYPEINFO_EQUALITY_INLINE
  78   #if !__GXX_WEAK__
  79     #define __GXX_TYPEINFO_EQUALITY_INLINE 0
  80   #else
  81     #define __GXX_TYPEINFO_EQUALITY_INLINE 1
  82   #endif
  83 #endif
  84
  85 namespace std
  86 {
  87   /**
  88    *  @brief  Part of RTTI.
  89    *
  90    *  The @c type_info class describes type information generated by
  91    *  an implementation.
  92   */
  93   class type_info
  94   {
  95   public:
  96     /** Destructor first. Being the first non-inline virtual function, this
  97      *  controls in which translation unit the vtable is emitted. The
  98      *  compiler makes use of that information to know where to emit
  99      *  the runtime-mandated type_info structures in the new-abi.  */
 100     virtual ~type_info();
 101
 102     /** Returns an @e implementation-defined byte string; this is not
 103      *  portable between compilers!  */
 104     const char* name() const
 105     { return __name; }
 106
 107 #if !__GXX_TYPEINFO_EQUALITY_INLINE
 108     bool before(const type_info& __arg) const;
 109
 110     // In old abi, or when weak symbols are not supported, there can
 111     // be multiple instances of a type_info object for one
 112     // type. Uniqueness must use the _name value, not object address.
 113     bool operator==(const type_info& __arg) const;
 114 #else
 115   #if !__GXX_MERGED_TYPEINFO_NAMES
 116     #error "Inline implementation of type_info comparision requires merging of type_info objects"
 117   #endif
 118     /** Returns true if @c *this precedes @c __arg in the implementation's
 119      *  collation order.  */
 120     // In new abi we can rely on type_info's NTBS being unique,
 121     // and therefore address comparisons are sufficient.
 122     bool before(const type_info& __arg) const
 123     { return __name < __arg.__name; }
 124
 125     bool operator==(const type_info& __arg) const
 126     { return __name == __arg.__name; }
 127 #endif
 128     bool operator!=(const type_info& __arg) const
 129     { return !operator==(__arg); }
 130
 131     // Return true if this is a pointer type of some kind
 132     virtual bool __is_pointer_p() const;
 133
 134     // Return true if this is a function type
 135     virtual bool __is_function_p() const;
 136
 137     // Try and catch a thrown type. Store an adjusted pointer to the
 138     // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then
 139     // THR_OBJ points to the thrown object. If THR_TYPE is a pointer
 140     // type, then THR_OBJ is the pointer itself. OUTER indicates the
 141     // number of outer pointers, and whether they were const
 142     // qualified.
 143     virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj,
 144                             unsigned __outer) const;
 145
 146     // Internally used during catch matching
 147     virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target,
 148                              void **__obj_ptr) const;
 149
 150   protected:
 151     const char *__name;
 152
 153     explicit type_info(const char *__n): __name(__n) { }
 154
 155   private:
 156     /// Assigning type_info is not supported.
 157     type_info& operator=(const type_info&);
 158     type_info(const type_info&);
 159   };
 160
 161   /**
 162    *  @brief  Thrown during incorrect typecasting.
 163    *
 164    *  If you attempt an invalid @c dynamic_cast expression, an instance of
 165    *  this class (or something derived from this class) is thrown.  */
 166   class bad_cast : public exception
 167   {
 168   public:
 169     bad_cast() throw() { }
 170
 171     // This declaration is not useless:
 172     // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
 173     virtual ~bad_cast() throw();
 174
 175     // See comment in eh_exception.cc.
 176     virtual const char* what() const throw();
 177   };
 178
 179   /** If you use a NULL pointer in a @c typeid expression, this is thrown.  */
 180   class bad_typeid : public exception
 181   {
 182   public:
 183     bad_typeid () throw() { }
 184
 185     // This declaration is not useless:
 186     // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
 187     virtual ~bad_typeid() throw();
 188
 189     // See comment in eh_exception.cc.
 190     virtual const char* what() const throw();
 191   };
 192 } // namespace std
 193
 194 #pragma GCC visibility pop
 195
 196 } // extern "C++"
 197 #endif