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 GNU CC.
   6 //
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   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 // GNU CC 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 GNU CC; see the file COPYING.  If not, write to
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  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   /** The @c type_info class describes type information generated by
  58    *  an implementation.
  59    *  @brief Used in RTTI.  */
  60   class type_info
  61   {
  62   public:
  63     /** Destructor. Being the first non-inline virtual function, this
  64      *  controls in which translation unit the vtable is emitted. The
  65      *  compiler makes use of that information to know where to emit
  66      *  the runtime-mandated type_info structures in the new-abi.  */
  67     virtual ~type_info();
  68
  69   private:
  70     /// Assigning type_info is not supported.  Made private.
  71     type_info& operator=(const type_info&);
  72     type_info(const type_info&);
  73
  74   protected:
  75     const char *__name;
  76
  77   protected:
  78     explicit type_info(const char *__n): __name(__n) { }
  79
  80   public:
  81     // the public interface
  82     /** Returns an @e implementation-defined byte string; this is not
  83      *  portable between compilers!  */
  84     const char* name() const
  85     { return __name; }
  86
  87 #if !__GXX_MERGED_TYPEINFO_NAMES
  88     bool before(const type_info& arg) const;
  89     // In old abi, or when weak symbols are not supported, there can
  90     // be multiple instances of a type_info object for one
  91     // type. Uniqueness must use the _name value, not object address.
  92     bool operator==(const type_info& __arg) const;
  93 #else
  94     /** Returns true if @c *this precedes @c __arg in the implementation's
  95      *  collation order.  */
  96     // In new abi we can rely on type_info's NTBS being unique,
  97     // and therefore address comparisons are sufficient.
  98     bool before(const type_info& __arg) const
  99     { return __name < __arg.__name; }
 100     bool operator==(const type_info& __arg) const
 101     { return __name == __arg.__name; }
 102 #endif
 103     bool operator!=(const type_info& __arg) const
 104     { return !operator==(__arg); }
 105
 106     // the internal interface
 107   public:
 108     // return true if this is a pointer type of some kind
 109     virtual bool __is_pointer_p() const;
 110     // return true if this is a function type
 111     virtual bool __is_function_p() const;
 112
 113     // Try and catch a thrown type. Store an adjusted pointer to the
 114     // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then
 115     // THR_OBJ points to the thrown object. If THR_TYPE is a pointer
 116     // type, then THR_OBJ is the pointer itself. OUTER indicates the
 117     // number of outer pointers, and whether they were const
 118     // qualified.
 119     virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj,
 120                             unsigned __outer) const;
 121
 122     // internally used during catch matching
 123     virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target,
 124                              void **__obj_ptr) const;
 125   };
 126
 127   /** If you attempt an invalid @c dynamic_cast expression, an instance of
 128    *  this class (or something derived from this class) is thrown.  */
 129   class bad_cast : public exception
 130   {
 131   public:
 132     bad_cast() throw() { }
 133     // This declaration is not useless:
 134     // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
 135     virtual ~bad_cast() throw();
 136   };
 137
 138   /** If you use a NULL pointer in a @c typeid expression, this is thrown.  */
 139   class bad_typeid : public exception
 140   {
 141   public:
 142     bad_typeid () throw() { }
 143     // This declaration is not useless:
 144     // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
 145     virtual ~bad_typeid() throw();
 146   };
 147 } // namespace std
 148
 149 } // extern "C++"
 150 #endif