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, 2012 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#pragma GCC visibility push(default) 42 43extern "C++" { 44 45namespace __cxxabiv1 46{ 47 class __class_type_info; 48} // namespace __cxxabiv1 49 50// Determine whether typeinfo names for the same type are merged (in which 51// case comparison can just compare pointers) or not (in which case strings 52// must be compared), and whether comparison is to be implemented inline or 53// not. We used to do inline pointer comparison by default if weak symbols 54// are available, but even with weak symbols sometimes names are not merged 55// when objects are loaded with RTLD_LOCAL, so now we always use strcmp by 56// default. For ABI compatibility, we do the strcmp inline if weak symbols 57// are available, and out-of-line if not. Out-of-line pointer comparison 58// is used where the object files are to be portable to multiple systems, 59// some of which may not be able to use pointer comparison, but the 60// particular system for which libstdc++ is being built can use pointer 61// comparison; in particular for most ARM EABI systems, where the ABI 62// specifies out-of-line comparison. The compiler's target configuration 63// can override the defaults by defining __GXX_TYPEINFO_EQUALITY_INLINE to 64// 1 or 0 to indicate whether or not comparison is inline, and 65// __GXX_MERGED_TYPEINFO_NAMES to 1 or 0 to indicate whether or not pointer 66// comparison can be used. 67 68#ifndef __GXX_MERGED_TYPEINFO_NAMES 69// By default, typeinfo names are not merged. 70#define __GXX_MERGED_TYPEINFO_NAMES 0 71#endif 72 73// By default follow the old inline rules to avoid ABI changes. 74#ifndef __GXX_TYPEINFO_EQUALITY_INLINE 75 #if !__GXX_WEAK__ 76 #define __GXX_TYPEINFO_EQUALITY_INLINE 0 77 #else 78 #define __GXX_TYPEINFO_EQUALITY_INLINE 1 79 #endif 80#endif 81 82namespace std 83{ 84 /** 85 * @brief Part of RTTI. 86 * 87 * The @c type_info class describes type information generated by 88 * an implementation. 89 */ 90 class type_info 91 { 92 public: 93 /** Destructor first. Being the first non-inline virtual function, this 94 * controls in which translation unit the vtable is emitted. The 95 * compiler makes use of that information to know where to emit 96 * the runtime-mandated type_info structures in the new-abi. */ 97 virtual ~type_info(); 98 99 /** Returns an @e implementation-defined byte string; this is not 100 * portable between compilers! */ 101 const char* name() const 102 { return __name[0] == '*' ? __name + 1 : __name; } 103 104#if !__GXX_TYPEINFO_EQUALITY_INLINE 105 // In old abi, or when weak symbols are not supported, there can 106 // be multiple instances of a type_info object for one 107 // type. Uniqueness must use the _name value, not object address. 108 bool before(const type_info& __arg) const; 109 bool operator==(const type_info& __arg) const; 110#else 111 #if !__GXX_MERGED_TYPEINFO_NAMES 112 /** Returns true if @c *this precedes @c __arg in the implementation's 113 * collation order. */ 114 // Even with the new abi, on systems that support dlopen 115 // we can run into cases where type_info names aren't merged, 116 // so we still need to do string comparison. 117 bool before(const type_info& __arg) const 118 { return (__name[0] == '*' && __arg.__name[0] == '*') 119 ? __name < __arg.__name 120 : __builtin_strcmp (__name, __arg.__name) < 0; } 121 122 bool operator==(const type_info& __arg) const 123 { 124 return ((__name == __arg.__name) 125 || (__name[0] != '*' && 126 __builtin_strcmp (__name, __arg.__name) == 0)); 127 } 128 #else 129 // On some targets we can rely on type_info's NTBS being unique, 130 // and therefore address comparisons are sufficient. 131 bool before(const type_info& __arg) const 132 { return __name < __arg.__name; } 133 134 bool operator==(const type_info& __arg) const 135 { return __name == __arg.__name; } 136 #endif 137#endif 138 bool operator!=(const type_info& __arg) const 139 { return !operator==(__arg); } 140 141#ifdef __GXX_EXPERIMENTAL_CXX0X__ 142 size_t hash_code() const noexcept 143 { 144# if !__GXX_MERGED_TYPEINFO_NAMES 145 return _Hash_bytes(name(), __builtin_strlen(name()), 146 static_cast<size_t>(0xc70f6907UL)); 147# else 148 return reinterpret_cast<size_t>(__name); 149# endif 150 } 151#endif // __GXX_EXPERIMENTAL_CXX0X__ 152 153 // Return true if this is a pointer type of some kind 154 virtual bool __is_pointer_p() const; 155 156 // Return true if this is a function type 157 virtual bool __is_function_p() const; 158 159 // Try and catch a thrown type. Store an adjusted pointer to the 160 // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then 161 // THR_OBJ points to the thrown object. If THR_TYPE is a pointer 162 // type, then THR_OBJ is the pointer itself. OUTER indicates the 163 // number of outer pointers, and whether they were const 164 // qualified. 165 virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj, 166 unsigned __outer) const; 167 168 // Internally used during catch matching 169 virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target, 170 void **__obj_ptr) const; 171 172 protected: 173 const char *__name; 174 175 explicit type_info(const char *__n): __name(__n) { } 176 177 private: 178 /// Assigning type_info is not supported. 179 type_info& operator=(const type_info&); 180 type_info(const type_info&); 181 }; 182 183 /** 184 * @brief Thrown during incorrect typecasting. 185 * @ingroup exceptions 186 * 187 * If you attempt an invalid @c dynamic_cast expression, an instance of 188 * this class (or something derived from this class) is thrown. */ 189 class bad_cast : public exception 190 { 191 public: 192 bad_cast() _GLIBCXX_USE_NOEXCEPT { } 193 194 // This declaration is not useless: 195 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 196 virtual ~bad_cast() _GLIBCXX_USE_NOEXCEPT; 197 198 // See comment in eh_exception.cc. 199 virtual const char* what() const _GLIBCXX_USE_NOEXCEPT; 200 }; 201 202 /** 203 * @brief Thrown when a NULL pointer in a @c typeid expression is used. 204 * @ingroup exceptions 205 */ 206 class bad_typeid : public exception 207 { 208 public: 209 bad_typeid () _GLIBCXX_USE_NOEXCEPT { } 210 211 // This declaration is not useless: 212 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 213 virtual ~bad_typeid() _GLIBCXX_USE_NOEXCEPT; 214 215 // See comment in eh_exception.cc. 216 virtual const char* what() const _GLIBCXX_USE_NOEXCEPT; 217 }; 218} // namespace std 219 220} // extern "C++" 221 222#pragma GCC visibility pop 223 224#endif 225