1 | // RTTI support for -*- C++ -*- |
2 | // Copyright (C) 1994-2017 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 |
223 | |