1// RTTI support for -*- C++ -*- 
2// Copyright (C) 1994-2019 Free Software Foundation, Inc. 
3// 
4// This file is part of GCC. 
5// 
6// GCC is free software; you can redistribute it and/or modify 
7// it under the terms of the GNU General Public License as published by 
8// the Free Software Foundation; either version 3, or (at your option) 
9// any later version. 
10// 
11// GCC is distributed in the hope that it will be useful, 
12// but WITHOUT ANY WARRANTY; without even the implied warranty of 
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
14// GNU General Public License for more details. 
15// 
16// Under Section 7 of GPL version 3, you are granted additional 
17// permissions described in the GCC Runtime Library Exception, version 
18// 3.1, as published by the Free Software Foundation. 
19 
20// You should have received a copy of the GNU General Public License and 
21// a copy of the GCC Runtime Library Exception along with this program; 
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 
23// <http://www.gnu.org/licenses/>. 
24 
25/** @file typeinfo 
26 * This is a Standard C++ Library header. 
27 */ 
28 
29#ifndef _TYPEINFO 
30#define _TYPEINFO 
31 
32#pragma GCC system_header 
33 
34#include <bits/exception.h> 
35#if __cplusplus >= 201103L 
36#include <bits/hash_bytes.h> 
37#endif 
38 
39#pragma GCC visibility push(default) 
40 
41extern "C++" { 
42 
43namespace __cxxabiv1 
44{ 
45 class __class_type_info; 
46} // namespace __cxxabiv1 
47 
48// Determine whether typeinfo names for the same type are merged (in which 
49// case comparison can just compare pointers) or not (in which case strings 
50// must be compared), and whether comparison is to be implemented inline or 
51// not. We used to do inline pointer comparison by default if weak symbols 
52// are available, but even with weak symbols sometimes names are not merged 
53// when objects are loaded with RTLD_LOCAL, so now we always use strcmp by 
54// default. For ABI compatibility, we do the strcmp inline if weak symbols 
55// are available, and out-of-line if not. Out-of-line pointer comparison 
56// is used where the object files are to be portable to multiple systems, 
57// some of which may not be able to use pointer comparison, but the 
58// particular system for which libstdc++ is being built can use pointer 
59// comparison; in particular for most ARM EABI systems, where the ABI 
60// specifies out-of-line comparison. The compiler's target configuration 
61// can override the defaults by defining __GXX_TYPEINFO_EQUALITY_INLINE to 
62// 1 or 0 to indicate whether or not comparison is inline, and 
63// __GXX_MERGED_TYPEINFO_NAMES to 1 or 0 to indicate whether or not pointer 
64// comparison can be used. 
65 
66#ifndef __GXX_MERGED_TYPEINFO_NAMES 
67// By default, typeinfo names are not merged. 
68#define __GXX_MERGED_TYPEINFO_NAMES 0 
69#endif 
70 
71// By default follow the old inline rules to avoid ABI changes. 
72#ifndef __GXX_TYPEINFO_EQUALITY_INLINE 
73 #if !__GXX_WEAK__ 
74 #define __GXX_TYPEINFO_EQUALITY_INLINE 0 
75 #else 
76 #define __GXX_TYPEINFO_EQUALITY_INLINE 1 
77 #endif 
78#endif 
79 
80namespace std 
81{ 
82 /** 
83 * @brief Part of RTTI. 
84 * 
85 * The @c type_info class describes type information generated by 
86 * an implementation. 
87 */ 
88 class type_info 
89 { 
90 public: 
91 /** Destructor first. Being the first non-inline virtual function, this 
92 * controls in which translation unit the vtable is emitted. The 
93 * compiler makes use of that information to know where to emit 
94 * the runtime-mandated type_info structures in the new-abi. */ 
95 virtual ~type_info(); 
96 
97 /** Returns an @e implementation-defined byte string; this is not 
98 * portable between compilers! */ 
99 const char* name() const _GLIBCXX_NOEXCEPT 
100 { return __name[0] == '*' ? __name + 1 : __name; } 
101 
102#if !__GXX_TYPEINFO_EQUALITY_INLINE 
103 // In old abi, or when weak symbols are not supported, there can 
104 // be multiple instances of a type_info object for one 
105 // type. Uniqueness must use the _name value, not object address. 
106 bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT; 
107 bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT; 
108#else 
109 #if !__GXX_MERGED_TYPEINFO_NAMES 
110 /** Returns true if @c *this precedes @c __arg in the implementation's 
111 * collation order. */ 
112 // Even with the new abi, on systems that support dlopen 
113 // we can run into cases where type_info names aren't merged, 
114 // so we still need to do string comparison. 
115 bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT 
116 { return (__name[0] == '*' && __arg.__name[0] == '*') 
117 ? __name < __arg.__name 
118 : __builtin_strcmp (__name, __arg.__name) < 0; } 
119 
120 bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT 
121 { 
122 return ((__name == __arg.__name) 
123 || (__name[0] != '*' && 
124 __builtin_strcmp (__name, __arg.__name) == 0)); 
125 } 
126 #else 
127 // On some targets we can rely on type_info's NTBS being unique, 
128 // and therefore address comparisons are sufficient. 
129 bool before(const type_info& __arg) const _GLIBCXX_NOEXCEPT 
130 { return __name < __arg.__name; } 
131 
132 bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT 
133 { return __name == __arg.__name; } 
134 #endif 
135#endif 
136 bool operator!=(const type_info& __arg) const _GLIBCXX_NOEXCEPT 
137 { return !operator==(__arg); } 
138 
139#if __cplusplus >= 201103L 
140 size_t hash_code() const noexcept 
141 { 
142# if !__GXX_MERGED_TYPEINFO_NAMES 
143 return _Hash_bytes(name(), __builtin_strlen(name()), 
144 static_cast<size_t>(0xc70f6907UL)); 
145# else 
146 return reinterpret_cast<size_t>(__name); 
147# endif 
148 } 
149#endif // C++11 
150 
151 // Return true if this is a pointer type of some kind 
152 virtual bool __is_pointer_p() const; 
153 
154 // Return true if this is a function type 
155 virtual bool __is_function_p() const; 
156 
157 // Try and catch a thrown type. Store an adjusted pointer to the 
158 // caught type in THR_OBJ. If THR_TYPE is not a pointer type, then 
159 // THR_OBJ points to the thrown object. If THR_TYPE is a pointer 
160 // type, then THR_OBJ is the pointer itself. OUTER indicates the 
161 // number of outer pointers, and whether they were const 
162 // qualified. 
163 virtual bool __do_catch(const type_info *__thr_type, void **__thr_obj, 
164 unsigned __outer) const; 
165 
166 // Internally used during catch matching 
167 virtual bool __do_upcast(const __cxxabiv1::__class_type_info *__target, 
168 void **__obj_ptr) const; 
169 
170 protected: 
171 const char *__name; 
172 
173 explicit type_info(const char *__n): __name(__n) { } 
174 
175 private: 
176 /// Assigning type_info is not supported. 
177 type_info& operator=(const type_info&); 
178 type_info(const type_info&); 
179 }; 
180 
181 /** 
182 * @brief Thrown during incorrect typecasting. 
183 * @ingroup exceptions 
184 * 
185 * If you attempt an invalid @c dynamic_cast expression, an instance of 
186 * this class (or something derived from this class) is thrown. */ 
187 class bad_cast : public exception 
188 { 
189 public: 
190 bad_cast() _GLIBCXX_USE_NOEXCEPT { } 
191 
192 // This declaration is not useless: 
193 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 
194 virtual ~bad_cast() _GLIBCXX_USE_NOEXCEPT; 
195 
196 // See comment in eh_exception.cc. 
197 virtual const char* what() const _GLIBCXX_USE_NOEXCEPT; 
198 }; 
199 
200 /** 
201 * @brief Thrown when a NULL pointer in a @c typeid expression is used. 
202 * @ingroup exceptions 
203 */ 
204 class bad_typeid : public exception 
205 { 
206 public: 
207 bad_typeid () _GLIBCXX_USE_NOEXCEPT { } 
208 
209 // This declaration is not useless: 
210 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118 
211 virtual ~bad_typeid() _GLIBCXX_USE_NOEXCEPT; 
212 
213 // See comment in eh_exception.cc. 
214 virtual const char* what() const _GLIBCXX_USE_NOEXCEPT; 
215 }; 
216} // namespace std 
217 
218} // extern "C++" 
219 
220#pragma GCC visibility pop 
221 
222#endif 
223