libstdc++
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00001 // RTTI support for -*- C++ -*- 00002 // Copyright (C) 1994-2013 Free Software Foundation, Inc. 00003 // 00004 // This file is part of GCC. 00005 // 00006 // GCC is free software; you can redistribute it and/or modify 00007 // it under the terms of the GNU General Public License as published by 00008 // the Free Software Foundation; either version 3, or (at your option) 00009 // any later version. 00010 // 00011 // GCC is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 // 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 /** @file typeinfo 00026 * This is a Standard C++ Library header. 00027 */ 00028 00029 #ifndef _TYPEINFO 00030 #define _TYPEINFO 00031 00032 #pragma GCC system_header 00033 00034 #include <exception> 00035 #if __cplusplus >= 201103L 00036 #include <bits/hash_bytes.h> 00037 #endif 00038 00039 #pragma GCC visibility push(default) 00040 00041 extern "C++" { 00042 00043 namespace __cxxabiv1 00044 { 00045 class __class_type_info; 00046 } // namespace __cxxabiv1 00047 00048 // Determine whether typeinfo names for the same type are merged (in which 00049 // case comparison can just compare pointers) or not (in which case strings 00050 // must be compared), and whether comparison is to be implemented inline or 00051 // not. We used to do inline pointer comparison by default if weak symbols 00052 // are available, but even with weak symbols sometimes names are not merged 00053 // when objects are loaded with RTLD_LOCAL, so now we always use strcmp by 00054 // default. For ABI compatibility, we do the strcmp inline if weak symbols 00055 // are available, and out-of-line if not. Out-of-line pointer comparison 00056 // is used where the object files are to be portable to multiple systems, 00057 // some of which may not be able to use pointer comparison, but the 00058 // particular system for which libstdc++ is being built can use pointer 00059 // comparison; in particular for most ARM EABI systems, where the ABI 00060 // specifies out-of-line comparison. The compiler's target configuration 00061 // can override the defaults by defining __GXX_TYPEINFO_EQUALITY_INLINE to 00062 // 1 or 0 to indicate whether or not comparison is inline, and 00063 // __GXX_MERGED_TYPEINFO_NAMES to 1 or 0 to indicate whether or not pointer 00064 // comparison can be used. 00065 00066 #ifndef __GXX_MERGED_TYPEINFO_NAMES 00067 // By default, typeinfo names are not merged. 00068 #define __GXX_MERGED_TYPEINFO_NAMES 0 00069 #endif 00070 00071 // By default follow the old inline rules to avoid ABI changes. 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 _GLIBCXX_NOEXCEPT 00100 { return __name[0] == '*' ? __name + 1 : __name; } 00101 00102 #if !__GXX_TYPEINFO_EQUALITY_INLINE 00103 // In old abi, or when weak symbols are not supported, there can 00104 // be multiple instances of a type_info object for one 00105 // type. Uniqueness must use the _name value, not object address. 00106 bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT; 00107 bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT; 00108 #else 00109 #if !__GXX_MERGED_TYPEINFO_NAMES 00110 /** Returns true if @c *this precedes @c __arg in the implementation's 00111 * collation order. */ 00112 // Even with the new abi, on systems that support dlopen 00113 // we can run into cases where type_info names aren't merged, 00114 // so we still need to do string comparison. 00115 bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT 00116 { return (__name[0] == '*' && __arg.__name[0] == '*') 00117 ? __name < __arg.__name 00118 : __builtin_strcmp (__name, __arg.__name) < 0; } 00119 00120 bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT 00121 { 00122 return ((__name == __arg.__name) 00123 || (__name[0] != '*' && 00124 __builtin_strcmp (__name, __arg.__name) == 0)); 00125 } 00126 #else 00127 // On some targets we can rely on type_info's NTBS being unique, 00128 // and therefore address comparisons are sufficient. 00129 bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT 00130 { return __name < __arg.__name; } 00131 00132 bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT 00133 { return __name == __arg.__name; } 00134 #endif 00135 #endif 00136 bool operator!=(const type_info& __arg) const _GLIBCXX_NOEXCEPT 00137 { return !operator==(__arg); } 00138 00139 #if __cplusplus >= 201103L 00140 size_t hash_code() const noexcept 00141 { 00142 # if !__GXX_MERGED_TYPEINFO_NAMES 00143 return _Hash_bytes(name(), __builtin_strlen(name()), 00144 static_cast<size_t>(0xc70f6907UL)); 00145 # else 00146 return reinterpret_cast<size_t>(__name); 00147 # endif 00148 } 00149 #endif // C++11 00150 00151 // Return true if this is a pointer type of some kind 00152 virtual bool __is_pointer_p() const; 00153 00154 // Return true if this is a function type 00155 virtual bool __is_function_p() const; 00156 00157 // Try and catch a thrown type. Store an adjusted pointer to the 00158 // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then 00159 // THR_OBJ points to the thrown object. If THR_TYPE is a pointer 00160 // type, then THR_OBJ is the pointer itself. OUTER indicates the 00161 // number of outer pointers, and whether they were const 00162 // qualified. 00163 virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj, 00164 unsigned __outer) const; 00165 00166 // Internally used during catch matching 00167 virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target, 00168 void **__obj_ptr) const; 00169 00170 protected: 00171 const char *__name; 00172 00173 explicit type_info(const char *__n): __name(__n) { } 00174 00175 private: 00176 /// Assigning type_info is not supported. 00177 type_info& operator=(const type_info&); 00178 type_info(const type_info&); 00179 }; 00180 00181 /** 00182 * @brief Thrown during incorrect typecasting. 00183 * @ingroup exceptions 00184 * 00185 * If you attempt an invalid @c dynamic_cast expression, an instance of 00186 * this class (or something derived from this class) is thrown. */ 00187 class bad_cast : public exception 00188 { 00189 public: 00190 bad_cast() _GLIBCXX_USE_NOEXCEPT { } 00191 00192 // This declaration is not useless: 00193 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 00194 virtual ~bad_cast() _GLIBCXX_USE_NOEXCEPT; 00195 00196 // See comment in eh_exception.cc. 00197 virtual const char* what() const _GLIBCXX_USE_NOEXCEPT; 00198 }; 00199 00200 /** 00201 * @brief Thrown when a NULL pointer in a @c typeid expression is used. 00202 * @ingroup exceptions 00203 */ 00204 class bad_typeid : public exception 00205 { 00206 public: 00207 bad_typeid () _GLIBCXX_USE_NOEXCEPT { } 00208 00209 // This declaration is not useless: 00210 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 00211 virtual ~bad_typeid() _GLIBCXX_USE_NOEXCEPT; 00212 00213 // See comment in eh_exception.cc. 00214 virtual const char* what() const _GLIBCXX_USE_NOEXCEPT; 00215 }; 00216 } // namespace std 00217 00218 } // extern "C++" 00219 00220 #pragma GCC visibility pop 00221 00222 #endif