typeinfo

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00001 // RTTI support for -*- C++ -*-
00002 // Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
00003 // 2003, 2004, 2005, 2006, 2007, 2009
00004 // Free Software Foundation
00005 //
00006 // This file is part of GCC.
00007 //
00008 // GCC is free software; you can redistribute it and/or modify
00009 // it under the terms of the GNU General Public License as published by
00010 // the Free Software Foundation; either version 3, or (at your option)
00011 // any later version.
00012 // 
00013 // GCC is distributed in the hope that it will be useful,
00014 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00015 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00016 // GNU General Public License for more details.
00017 // 
00018 // Under Section 7 of GPL version 3, you are granted additional
00019 // permissions described in the GCC Runtime Library Exception, version
00020 // 3.1, as published by the Free Software Foundation.
00021 
00022 // You should have received a copy of the GNU General Public License and
00023 // a copy of the GCC Runtime Library Exception along with this program;
00024 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00025 // <http://www.gnu.org/licenses/>.
00026 
00027 /** @file typeinfo
00028  *  This is a Standard C++ Library header.
00029  */
00030 
00031 #ifndef _TYPEINFO
00032 #define _TYPEINFO
00033 
00034 #include <exception>
00035 
00036 #pragma GCC visibility push(default)
00037 
00038 extern "C++" {
00039 
00040 namespace __cxxabiv1
00041 {
00042   class __class_type_info;
00043 } // namespace __cxxabiv1
00044 
00045 // Determine whether typeinfo names for the same type are merged (in which
00046 // case comparison can just compare pointers) or not (in which case
00047 // strings must be compared and g++.dg/abi/local1.C will fail), and
00048 // whether comparison is to be implemented inline or not.  By default we
00049 // use inline pointer comparison if weak symbols are available, and
00050 // out-of-line strcmp if not.  Out-of-line pointer comparison is used
00051 // where the object files are to be portable to multiple systems, some of
00052 // which may not be able to use pointer comparison, but the particular
00053 // system for which libstdc++ is being built can use pointer comparison;
00054 // in particular for most ARM EABI systems, where the ABI specifies
00055 // out-of-line comparison.  Inline strcmp is not currently supported.  The
00056 // compiler's target configuration can override the defaults by defining
00057 // __GXX_TYPEINFO_EQUALITY_INLINE to 1 or 0 to indicate whether or not
00058 // comparison is inline, and __GXX_MERGED_TYPEINFO_NAMES to 1 or 0 to
00059 // indicate whether or not pointer comparison can be used.
00060 
00061 #ifndef __GXX_MERGED_TYPEINFO_NAMES
00062   #if !__GXX_WEAK__
00063     // If weak symbols are not supported, typeinfo names are not merged.
00064     #define __GXX_MERGED_TYPEINFO_NAMES 0
00065   #else
00066     // On platforms that support weak symbols, typeinfo names are merged.
00067     #define __GXX_MERGED_TYPEINFO_NAMES 1
00068   #endif
00069 #endif
00070 
00071 // By default follow the same rules as for __GXX_MERGED_TYPEINFO_NAMES.
00072 #ifndef __GXX_TYPEINFO_EQUALITY_INLINE
00073   #if !__GXX_WEAK__
00074     #define __GXX_TYPEINFO_EQUALITY_INLINE 0
00075   #else
00076     #define __GXX_TYPEINFO_EQUALITY_INLINE 1
00077   #endif
00078 #endif
00079 
00080 namespace std 
00081 {
00082   /**
00083    *  @brief  Part of RTTI.
00084    *
00085    *  The @c type_info class describes type information generated by
00086    *  an implementation.
00087   */
00088   class type_info 
00089   {
00090   public:
00091     /** Destructor first. Being the first non-inline virtual function, this
00092      *  controls in which translation unit the vtable is emitted. The
00093      *  compiler makes use of that information to know where to emit
00094      *  the runtime-mandated type_info structures in the new-abi.  */
00095     virtual ~type_info();
00096 
00097     /** Returns an @e implementation-defined byte string; this is not
00098      *  portable between compilers!  */
00099     const char* name() const
00100     { return __name; }
00101 
00102 #if !__GXX_TYPEINFO_EQUALITY_INLINE
00103     bool before(const type_info& __arg) const;
00104 
00105     // In old abi, or when weak symbols are not supported, there can
00106     // be multiple instances of a type_info object for one
00107     // type. Uniqueness must use the _name value, not object address.
00108     bool operator==(const type_info& __arg) const;
00109 #else
00110   #if !__GXX_MERGED_TYPEINFO_NAMES
00111     #error "Inline implementation of type_info comparision requires merging of type_info objects"
00112   #endif
00113     /** Returns true if @c *this precedes @c __arg in the implementation's
00114      *  collation order.  */
00115     // In new abi we can rely on type_info's NTBS being unique,
00116     // and therefore address comparisons are sufficient.
00117     bool before(const type_info& __arg) const
00118     { return __name < __arg.__name; }
00119 
00120     bool operator==(const type_info& __arg) const
00121     { return __name == __arg.__name; }
00122 #endif
00123     bool operator!=(const type_info& __arg) const
00124     { return !operator==(__arg); }
00125 
00126     // Return true if this is a pointer type of some kind
00127     virtual bool __is_pointer_p() const;
00128 
00129     // Return true if this is a function type
00130     virtual bool __is_function_p() const;
00131 
00132     // Try and catch a thrown type. Store an adjusted pointer to the
00133     // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then
00134     // THR_OBJ points to the thrown object. If THR_TYPE is a pointer
00135     // type, then THR_OBJ is the pointer itself. OUTER indicates the
00136     // number of outer pointers, and whether they were const
00137     // qualified.
00138     virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj,
00139                 unsigned __outer) const;
00140 
00141     // Internally used during catch matching
00142     virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target,
00143                  void **__obj_ptr) const;
00144 
00145   protected:
00146     const char *__name;
00147     
00148     explicit type_info(const char *__n): __name(__n) { }
00149     
00150   private:
00151     /// Assigning type_info is not supported.
00152     type_info& operator=(const type_info&);
00153     type_info(const type_info&);
00154   };
00155 
00156   /**
00157    *  @brief  Thrown during incorrect typecasting.
00158    *  @ingroup exceptions
00159    *
00160    *  If you attempt an invalid @c dynamic_cast expression, an instance of
00161    *  this class (or something derived from this class) is thrown.  */
00162   class bad_cast : public exception 
00163   {
00164   public:
00165     bad_cast() throw() { }
00166 
00167     // This declaration is not useless:
00168     // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
00169     virtual ~bad_cast() throw();
00170 
00171     // See comment in eh_exception.cc.
00172     virtual const char* what() const throw();
00173   };
00174   
00175   /** 
00176    *  @brief Thrown when a NULL pointer in a @c typeid expression is used.
00177    *  @ingroup exceptions
00178    */
00179   class bad_typeid : public exception 
00180   {
00181   public:
00182     bad_typeid () throw() { }
00183 
00184     // This declaration is not useless:
00185     // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
00186     virtual ~bad_typeid() throw();
00187 
00188     // See comment in eh_exception.cc.
00189     virtual const char* what() const throw();
00190   };
00191 } // namespace std
00192 
00193 #pragma GCC visibility pop
00194 
00195 } // extern "C++"
00196 #endif

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