1 // RTTI support for -*- C++ -*- 2 // Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 3 // 2003, 2004, 2005, 2006, 2007, 2009, 2010, 2011 4 // Free Software Foundation 5 // 6 // This file is part of GCC. 7 // 8 // GCC is free software; you can redistribute it and/or modify 9 // it under the terms of the GNU General Public License as published by 10 // the Free Software Foundation; either version 3, or (at your option) 11 // any later version. 12 // 13 // GCC is distributed in the hope that it will be useful, 14 // but WITHOUT ANY WARRANTY; without even the implied warranty of 15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 // GNU General Public License for more details. 17 // 18 // Under Section 7 of GPL version 3, you are granted additional 19 // permissions described in the GCC Runtime Library Exception, version 20 // 3.1, as published by the Free Software Foundation. 21 22 // You should have received a copy of the GNU General Public License and 23 // a copy of the GCC Runtime Library Exception along with this program; 24 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 25 // <http://www.gnu.org/licenses/>. 26 27 /** @file typeinfo 28 * This is a Standard C++ Library header. 29 */ 30 31 #ifndef _TYPEINFO 32 #define _TYPEINFO 33 34 #pragma GCC system_header 35 36 #include <exception> 37 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 38 #include <bits/hash_bytes.h> 39 #endif 40 41 42 #pragma GCC visibility push(default) 43 44 extern "C++" { 45 46 namespace __cxxabiv1 47 { 48 class __class_type_info; 49 } // namespace __cxxabiv1 50 51 // Determine whether typeinfo names for the same type are merged (in which 52 // case comparison can just compare pointers) or not (in which case strings 53 // must be compared), and whether comparison is to be implemented inline or 54 // not. We used to do inline pointer comparison by default if weak symbols 55 // are available, but even with weak symbols sometimes names are not merged 56 // when objects are loaded with RTLD_LOCAL, so now we always use strcmp by 57 // default. For ABI compatibility, we do the strcmp inline if weak symbols 58 // are available, and out-of-line if not. Out-of-line pointer comparison 59 // is used where the object files are to be portable to multiple systems, 60 // some of which may not be able to use pointer comparison, but the 61 // particular system for which libstdc++ is being built can use pointer 62 // comparison; in particular for most ARM EABI systems, where the ABI 63 // specifies out-of-line comparison. The compiler's target configuration 64 // can override the defaults by defining __GXX_TYPEINFO_EQUALITY_INLINE to 65 // 1 or 0 to indicate whether or not comparison is inline, and 66 // __GXX_MERGED_TYPEINFO_NAMES to 1 or 0 to indicate whether or not pointer 67 // comparison can be used. 68 69 #ifndef __GXX_MERGED_TYPEINFO_NAMES 70 // By default, typeinfo names are not merged. 71 #define __GXX_MERGED_TYPEINFO_NAMES 0 72 #endif 73 74 // By default follow the old inline rules to avoid ABI changes. 75 #ifndef __GXX_TYPEINFO_EQUALITY_INLINE 76 #if !__GXX_WEAK__ 77 #define __GXX_TYPEINFO_EQUALITY_INLINE 0 78 #else 79 #define __GXX_TYPEINFO_EQUALITY_INLINE 1 80 #endif 81 #endif 82 83 namespace std 84 { 85 /** 86 * @brief Part of RTTI. 87 * 88 * The @c type_info class describes type information generated by 89 * an implementation. 90 */ 91 class type_info 92 { 93 public: 94 /** Destructor first. Being the first non-inline virtual function, this 95 * controls in which translation unit the vtable is emitted. The 96 * compiler makes use of that information to know where to emit 97 * the runtime-mandated type_info structures in the new-abi. */ 98 virtual ~type_info(); 99 100 /** Returns an @e implementation-defined byte string; this is not 101 * portable between compilers! */ 102 const char* name() const 103 { return __name[0] == '*' ? __name + 1 : __name; } 104 105 #if !__GXX_TYPEINFO_EQUALITY_INLINE 106 // In old abi, or when weak symbols are not supported, there can 107 // be multiple instances of a type_info object for one 108 // type. Uniqueness must use the _name value, not object address. 109 bool before(const type_info& __arg) const; 110 bool operator==(const type_info& __arg) const; 111 #else 112 #if !__GXX_MERGED_TYPEINFO_NAMES 113 /** Returns true if @c *this precedes @c __arg in the implementation's 114 * collation order. */ 115 // Even with the new abi, on systems that support dlopen 116 // we can run into cases where type_info names aren't merged, 117 // so we still need to do string comparison. 118 bool before(const type_info& __arg) const 119 { return (__name[0] == '*' && __arg.__name[0] == '*') 120 ? __name < __arg.__name 121 : __builtin_strcmp (__name, __arg.__name) < 0; } 122 123 bool operator==(const type_info& __arg) const 124 { 125 return ((__name == __arg.__name) 126 || (__name[0] != '*' && 127 __builtin_strcmp (__name, __arg.__name) == 0)); 128 } 129 #else 130 // On some targets we can rely on type_info's NTBS being unique, 131 // and therefore address comparisons are sufficient. 132 bool before(const type_info& __arg) const 133 { return __name < __arg.__name; } 134 135 bool operator==(const type_info& __arg) const 136 { return __name == __arg.__name; } 137 #endif 138 #endif 139 bool operator!=(const type_info& __arg) const 140 { return !operator==(__arg); } 141 142 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 143 size_t hash_code() const noexcept 144 { 145 # if !__GXX_MERGED_TYPEINFO_NAMES 146 return _Hash_bytes(name(), __builtin_strlen(name()), 147 static_cast<size_t>(0xc70f6907UL)); 148 # else 149 return reinterpret_cast<size_t>(__name); 150 # endif 151 } 152 #endif // __GXX_EXPERIMENTAL_CXX0X__ 153 154 // Return true if this is a pointer type of some kind 155 virtual bool __is_pointer_p() const; 156 157 // Return true if this is a function type 158 virtual bool __is_function_p() const; 159 160 // Try and catch a thrown type. Store an adjusted pointer to the 161 // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then 162 // THR_OBJ points to the thrown object. If THR_TYPE is a pointer 163 // type, then THR_OBJ is the pointer itself. OUTER indicates the 164 // number of outer pointers, and whether they were const 165 // qualified. 166 virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj, 167 unsigned __outer) const; 168 169 // Internally used during catch matching 170 virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target, 171 void **__obj_ptr) const; 172 173 protected: 174 const char *__name; 175 176 explicit type_info(const char *__n): __name(__n) { } 177 178 private: 179 /// Assigning type_info is not supported. 180 type_info& operator=(const type_info&); 181 type_info(const type_info&); 182 }; 183 184 /** 185 * @brief Thrown during incorrect typecasting. 186 * @ingroup exceptions 187 * 188 * If you attempt an invalid @c dynamic_cast expression, an instance of 189 * this class (or something derived from this class) is thrown. */ 190 class bad_cast : public exception 191 { 192 public: 193 bad_cast() throw() { } 194 195 // This declaration is not useless: 196 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 197 virtual ~bad_cast() throw(); 198 199 // See comment in eh_exception.cc. 200 virtual const char* what() const throw(); 201 }; 202 203 /** 204 * @brief Thrown when a NULL pointer in a @c typeid expression is used. 205 * @ingroup exceptions 206 */ 207 class bad_typeid : public exception 208 { 209 public: 210 bad_typeid () throw() { } 211 212 // This declaration is not useless: 213 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 214 virtual ~bad_typeid() throw(); 215 216 // See comment in eh_exception.cc. 217 virtual const char* what() const throw(); 218 }; 219 } // namespace std 220 221 #pragma GCC visibility pop 222 223 } // extern "C++" 224 #endif 225
