type_info类用于描述类型的类，type_info头文件定义了两个异常类bad_cast、bad_typeid。
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// RTTI support for -*- C++ -*- // Copyright (C) 1994, 1995, 1996, 1997, 1998, 2000, 2001, 2002 // Free Software Foundation // // This file is part of GCC. // // GCC is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 2, or (at your option) // any later version. // // GCC is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // You should have received a copy of the GNU General Public License // along with GCC; see the file COPYING. If not, write to // the Free Software Foundation, 59 Temple Place - Suite 330, // Boston, MA 02111-1307, USA. // As a special exception, you may use this file as part of a free software // library without restriction. Specifically, if other files instantiate // templates or use macros or inline functions from this file, or you compile // this file and link it with other files to produce an executable, this // file does not by itself cause the resulting executable to be covered by // the GNU General Public License. This exception does not however // invalidate any other reasons why the executable file might be covered by // the GNU General Public License. /** @file typeinfo * This header provides RTTI support. */ #ifndef _TYPEINFO #define _TYPEINFO #include <exception> extern "C++" { namespace __cxxabiv1 { class __class_type_info; } // namespace __cxxabiv1 #if !__GXX_WEAK__ || defined (__MINGW32__) || defined (__CYGWIN__) // If weak symbols are not supported, typeinfo names are not merged. #define __GXX_MERGED_TYPEINFO_NAMES 0 #else // On platforms that support weak symbols, typeinfo names are merged. #define __GXX_MERGED_TYPEINFO_NAMES 1 #endif namespace std { /** * @brief Part of RTTI. * * The @c type_info class describes type information generated by * an implementation. */ class type_info { public: /** Destructor. Being the first non-inline virtual function, this * controls in which translation unit the vtable is emitted. The * compiler makes use of that information to know where to emit * the runtime-mandated type_info structures in the new-abi. */ virtual ~type_info(); private: /// Assigning type_info is not supported. Made private. type_info& operator=(const type_info&); type_info(const type_info&); protected: const char *__name; protected: explicit type_info(const char *__n): __name(__n) { } public: // the public interface /** Returns an @e implementation-defined byte string; this is not * portable between compilers! */ const char* name() const { return __name; } #if !__GXX_MERGED_TYPEINFO_NAMES bool before(const type_info& __arg) const; // In old abi, or when weak symbols are not supported, there can // be multiple instances of a type_info object for one // type. Uniqueness must use the _name value, not object address. bool operator==(const type_info& __arg) const; #else /** Returns true if @c *this precedes @c __arg in the implementation's * collation order. */ // In new abi we can rely on type_info's NTBS being unique, // and therefore address comparisons are sufficient. bool before(const type_info& __arg) const { return __name < __arg.__name; } bool operator==(const type_info& __arg) const { return __name == __arg.__name; } #endif bool operator!=(const type_info& __arg) const { return !operator==(__arg); } // the internal interface public: // return true if this is a pointer type of some kind virtual bool __is_pointer_p() const; // return true if this is a function type virtual bool __is_function_p() const; // Try and catch a thrown type. Store an adjusted pointer to the // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then // THR_OBJ points to the thrown object. If THR_TYPE is a pointer // type, then THR_OBJ is the pointer itself. OUTER indicates the // number of outer pointers, and whether they were const // qualified. virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj, unsigned __outer) const; // internally used during catch matching virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target, void **__obj_ptr) const; }; /** * @brief Thrown during incorrect typecasting. * * If you attempt an invalid @c dynamic_cast expression, an instance of * this class (or something derived from this class) is thrown. */ class bad_cast : public exception { public: bad_cast() throw() { } // This declaration is not useless: // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 virtual ~bad_cast() throw(); }; /** If you use a NULL pointer in a @c typeid expression, this is thrown. */ class bad_typeid : public exception { public: bad_typeid () throw() { } // This declaration is not useless: // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 virtual ~bad_typeid() throw(); }; } // namespace std } // extern "C++" #endif |
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