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1 | // RTTI support for -*- C++ -*- | |
2 | // Copyright (C) 1994-2018 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 | ||
41 | extern "C++" { | |
42 | ||
43 | namespace __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 | ||
80 | namespace 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 |