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1 : // RTTI support for -*- C++ -*-
2 : // Copyright (C) 1994-2013 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 <exception>
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 24717 : bool operator==(const type_info& __arg) const _GLIBCXX_NOEXCEPT
121 : {
122 24717 : return ((__name == __arg.__name)
123 24717 : || (__name[0] != '*' &&
124 24717 : __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
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