libstdc++
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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, 2010, 2011, 2012 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 #pragma GCC system_header 00035 00036 #include <exception> 00037 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 00038 #include <bits/hash_bytes.h> 00039 #endif 00040 00041 #pragma GCC visibility push(default) 00042 00043 extern "C++" { 00044 00045 namespace __cxxabiv1 00046 { 00047 class __class_type_info; 00048 } // namespace __cxxabiv1 00049 00050 // Determine whether typeinfo names for the same type are merged (in which 00051 // case comparison can just compare pointers) or not (in which case strings 00052 // must be compared), and whether comparison is to be implemented inline or 00053 // not. We used to do inline pointer comparison by default if weak symbols 00054 // are available, but even with weak symbols sometimes names are not merged 00055 // when objects are loaded with RTLD_LOCAL, so now we always use strcmp by 00056 // default. For ABI compatibility, we do the strcmp inline if weak symbols 00057 // are available, and out-of-line if not. Out-of-line pointer comparison 00058 // is used where the object files are to be portable to multiple systems, 00059 // some of which may not be able to use pointer comparison, but the 00060 // particular system for which libstdc++ is being built can use pointer 00061 // comparison; in particular for most ARM EABI systems, where the ABI 00062 // specifies out-of-line comparison. The compiler's target configuration 00063 // can override the defaults by defining __GXX_TYPEINFO_EQUALITY_INLINE to 00064 // 1 or 0 to indicate whether or not comparison is inline, and 00065 // __GXX_MERGED_TYPEINFO_NAMES to 1 or 0 to indicate whether or not pointer 00066 // comparison can be used. 00067 00068 #ifndef __GXX_MERGED_TYPEINFO_NAMES 00069 // By default, typeinfo names are not merged. 00070 #define __GXX_MERGED_TYPEINFO_NAMES 0 00071 #endif 00072 00073 // By default follow the old inline rules to avoid ABI changes. 00074 #ifndef __GXX_TYPEINFO_EQUALITY_INLINE 00075 #if !__GXX_WEAK__ 00076 #define __GXX_TYPEINFO_EQUALITY_INLINE 0 00077 #else 00078 #define __GXX_TYPEINFO_EQUALITY_INLINE 1 00079 #endif 00080 #endif 00081 00082 namespace std 00083 { 00084 /** 00085 * @brief Part of RTTI. 00086 * 00087 * The @c type_info class describes type information generated by 00088 * an implementation. 00089 */ 00090 class type_info 00091 { 00092 public: 00093 /** Destructor first. Being the first non-inline virtual function, this 00094 * controls in which translation unit the vtable is emitted. The 00095 * compiler makes use of that information to know where to emit 00096 * the runtime-mandated type_info structures in the new-abi. */ 00097 virtual ~type_info(); 00098 00099 /** Returns an @e implementation-defined byte string; this is not 00100 * portable between compilers! */ 00101 const char* name() const 00102 { return __name[0] == '*' ? __name + 1 : __name; } 00103 00104 #if !__GXX_TYPEINFO_EQUALITY_INLINE 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 before(const type_info& __arg) const; 00109 bool operator==(const type_info& __arg) const; 00110 #else 00111 #if !__GXX_MERGED_TYPEINFO_NAMES 00112 /** Returns true if @c *this precedes @c __arg in the implementation's 00113 * collation order. */ 00114 // Even with the new abi, on systems that support dlopen 00115 // we can run into cases where type_info names aren't merged, 00116 // so we still need to do string comparison. 00117 bool before(const type_info& __arg) const 00118 { return (__name[0] == '*' && __arg.__name[0] == '*') 00119 ? __name < __arg.__name 00120 : __builtin_strcmp (__name, __arg.__name) < 0; } 00121 00122 bool operator==(const type_info& __arg) const 00123 { 00124 return ((__name == __arg.__name) 00125 || (__name[0] != '*' && 00126 __builtin_strcmp (__name, __arg.__name) == 0)); 00127 } 00128 #else 00129 // On some targets we can rely on type_info's NTBS being unique, 00130 // and therefore address comparisons are sufficient. 00131 bool before(const type_info& __arg) const 00132 { return __name < __arg.__name; } 00133 00134 bool operator==(const type_info& __arg) const 00135 { return __name == __arg.__name; } 00136 #endif 00137 #endif 00138 bool operator!=(const type_info& __arg) const 00139 { return !operator==(__arg); } 00140 00141 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 00142 size_t hash_code() const noexcept 00143 { 00144 # if !__GXX_MERGED_TYPEINFO_NAMES 00145 return _Hash_bytes(name(), __builtin_strlen(name()), 00146 static_cast<size_t>(0xc70f6907UL)); 00147 # else 00148 return reinterpret_cast<size_t>(__name); 00149 # endif 00150 } 00151 #endif // __GXX_EXPERIMENTAL_CXX0X__ 00152 00153 // Return true if this is a pointer type of some kind 00154 virtual bool __is_pointer_p() const; 00155 00156 // Return true if this is a function type 00157 virtual bool __is_function_p() const; 00158 00159 // Try and catch a thrown type. Store an adjusted pointer to the 00160 // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then 00161 // THR_OBJ points to the thrown object. If THR_TYPE is a pointer 00162 // type, then THR_OBJ is the pointer itself. OUTER indicates the 00163 // number of outer pointers, and whether they were const 00164 // qualified. 00165 virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj, 00166 unsigned __outer) const; 00167 00168 // Internally used during catch matching 00169 virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target, 00170 void **__obj_ptr) const; 00171 00172 protected: 00173 const char *__name; 00174 00175 explicit type_info(const char *__n): __name(__n) { } 00176 00177 private: 00178 /// Assigning type_info is not supported. 00179 type_info& operator=(const type_info&); 00180 type_info(const type_info&); 00181 }; 00182 00183 /** 00184 * @brief Thrown during incorrect typecasting. 00185 * @ingroup exceptions 00186 * 00187 * If you attempt an invalid @c dynamic_cast expression, an instance of 00188 * this class (or something derived from this class) is thrown. */ 00189 class bad_cast : public exception 00190 { 00191 public: 00192 bad_cast() _GLIBCXX_USE_NOEXCEPT { } 00193 00194 // This declaration is not useless: 00195 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 00196 virtual ~bad_cast() _GLIBCXX_USE_NOEXCEPT; 00197 00198 // See comment in eh_exception.cc. 00199 virtual const char* what() const _GLIBCXX_USE_NOEXCEPT; 00200 }; 00201 00202 /** 00203 * @brief Thrown when a NULL pointer in a @c typeid expression is used. 00204 * @ingroup exceptions 00205 */ 00206 class bad_typeid : public exception 00207 { 00208 public: 00209 bad_typeid () _GLIBCXX_USE_NOEXCEPT { } 00210 00211 // This declaration is not useless: 00212 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 00213 virtual ~bad_typeid() _GLIBCXX_USE_NOEXCEPT; 00214 00215 // See comment in eh_exception.cc. 00216 virtual const char* what() const _GLIBCXX_USE_NOEXCEPT; 00217 }; 00218 } // namespace std 00219 00220 } // extern "C++" 00221 00222 #pragma GCC visibility pop 00223 00224 #endif