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1 | // The -*- C++ -*- type traits classes for internal use in libstdc++ |
2 | ||
c0736a9d PC |
3 | // Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005 |
4 | // Free Software Foundation, Inc. | |
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5 | // |
6 | // This file is part of the GNU ISO C++ Library. This library is free | |
7 | // software; you can redistribute it and/or modify it under the | |
8 | // terms of the GNU General Public License as published by the | |
9 | // Free Software Foundation; either version 2, or (at your option) | |
10 | // any later version. | |
11 | ||
12 | // This library is distributed in the hope that it will be useful, | |
13 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | // GNU General Public License for more details. | |
16 | ||
17 | // You should have received a copy of the GNU General Public License along | |
18 | // with this library; see the file COPYING. If not, write to the Free | |
83f51799 | 19 | // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, |
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20 | // USA. |
21 | ||
22 | // As a special exception, you may use this file as part of a free software | |
23 | // library without restriction. Specifically, if other files instantiate | |
24 | // templates or use macros or inline functions from this file, or you compile | |
25 | // this file and link it with other files to produce an executable, this | |
26 | // file does not by itself cause the resulting executable to be covered by | |
27 | // the GNU General Public License. This exception does not however | |
28 | // invalidate any other reasons why the executable file might be covered by | |
29 | // the GNU General Public License. | |
30 | ||
31 | // Written by Gabriel Dos Reis <dosreis@cmla.ens-cachan.fr> | |
32 | ||
729e3d3f PE |
33 | /** @file cpp_type_traits.h |
34 | * This is an internal header file, included by other library headers. | |
35 | * You should not attempt to use it directly. | |
36 | */ | |
37 | ||
3d7c150e BK |
38 | #ifndef _CPP_TYPE_TRAITS_H |
39 | #define _CPP_TYPE_TRAITS_H 1 | |
725dc051 | 40 | |
b0a85b86 GDR |
41 | #pragma GCC system_header |
42 | ||
c0736a9d PC |
43 | #include <bits/c++config.h> |
44 | ||
725dc051 BK |
45 | // |
46 | // This file provides some compile-time information about various types. | |
ca6c4418 | 47 | // These representations were designed, on purpose, to be constant-expressions |
5e91e92e | 48 | // and not types as found in <bits/type_traits.h>. In particular, they |
725dc051 BK |
49 | // can be used in control structures and the optimizer hopefully will do |
50 | // the obvious thing. | |
51 | // | |
52 | // Why integral expressions, and not functions nor types? | |
ca6c4418 GDR |
53 | // Firstly, these compile-time entities are used as template-arguments |
54 | // so function return values won't work: We need compile-time entities. | |
55 | // We're left with types and constant integral expressions. | |
56 | // Secondly, from the point of view of ease of use, type-based compile-time | |
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57 | // information is -not- *that* convenient. On has to write lots of |
58 | // overloaded functions and to hope that the compiler will select the right | |
59 | // one. As a net effect, the overall structure isn't very clear at first | |
60 | // glance. | |
ca6c4418 GDR |
61 | // Thirdly, partial ordering and overload resolution (of function templates) |
62 | // is highly costly in terms of compiler-resource. It is a Good Thing to | |
725dc051 BK |
63 | // keep these resource consumption as least as possible. |
64 | // | |
ca6c4418 GDR |
65 | // See valarray_array.h for a case use. |
66 | // | |
725dc051 BK |
67 | // -- Gaby (dosreis@cmla.ens-cachan.fr) 2000-03-06. |
68 | // | |
c0736a9d PC |
69 | // Update 2005: types are also provided and <bits/type_traits.h> has been |
70 | // removed. | |
71 | // | |
725dc051 | 72 | |
ff89096a PC |
73 | // NB: g++ can not compile these if declared within the class |
74 | // __is_pod itself. | |
75 | namespace __gnu_internal | |
76 | { | |
77 | typedef char __one; | |
78 | typedef char __two[2]; | |
79 | ||
4d73fac9 PC |
80 | template<typename _Tp> |
81 | __one __test_type(int _Tp::*); | |
82 | template<typename _Tp> | |
83 | __two& __test_type(...); | |
ff89096a PC |
84 | } // namespace __gnu_internal |
85 | ||
5e91e92e | 86 | // Forward declaration hack, should really include this from somewhere. |
3cbc7af0 BK |
87 | _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx) |
88 | ||
5e91e92e PC |
89 | template<typename _Iterator, typename _Container> |
90 | class __normal_iterator; | |
3cbc7af0 BK |
91 | |
92 | _GLIBCXX_END_NAMESPACE | |
5e91e92e | 93 | |
c0736a9d PC |
94 | struct __true_type { }; |
95 | struct __false_type { }; | |
96 | ||
3cbc7af0 BK |
97 | _GLIBCXX_BEGIN_NAMESPACE(std) |
98 | ||
c0736a9d PC |
99 | template<bool> |
100 | struct __truth_type | |
101 | { typedef __false_type __type; }; | |
102 | ||
103 | template<> | |
104 | struct __truth_type<true> | |
105 | { typedef __true_type __type; }; | |
106 | ||
a9dd5a46 PC |
107 | // N.B. The conversions to bool are needed due to the issue |
108 | // explained in c++/19404. | |
c0736a9d PC |
109 | template<class _Sp, class _Tp> |
110 | struct __traitor | |
111 | { | |
a9dd5a46 | 112 | enum { __value = bool(_Sp::__value) || bool(_Tp::__value) }; |
4d73fac9 | 113 | typedef typename __truth_type<__value>::__type __type; |
c0736a9d PC |
114 | }; |
115 | ||
cdc958d8 GDR |
116 | // Compare for equality of types. |
117 | template<typename, typename> | |
118 | struct __are_same | |
119 | { | |
4d73fac9 PC |
120 | enum { __value = 0 }; |
121 | typedef __false_type __type; | |
cdc958d8 GDR |
122 | }; |
123 | ||
124 | template<typename _Tp> | |
125 | struct __are_same<_Tp, _Tp> | |
126 | { | |
4d73fac9 PC |
127 | enum { __value = 1 }; |
128 | typedef __true_type __type; | |
cdc958d8 GDR |
129 | }; |
130 | ||
131 | // Define a nested type if some predicate holds. | |
132 | template<typename, bool> | |
133 | struct __enable_if | |
c0736a9d | 134 | { |
cdc958d8 GDR |
135 | }; |
136 | ||
137 | template<typename _Tp> | |
ff89096a | 138 | struct __enable_if<_Tp, true> |
cdc958d8 | 139 | { |
4d73fac9 | 140 | typedef _Tp __type; |
cdc958d8 GDR |
141 | }; |
142 | ||
143 | // Holds if the template-argument is a void type. | |
725dc051 | 144 | template<typename _Tp> |
ca6c4418 | 145 | struct __is_void |
725dc051 | 146 | { |
4d73fac9 | 147 | enum { __value = 0 }; |
c0736a9d | 148 | typedef __false_type __type; |
725dc051 | 149 | }; |
725dc051 BK |
150 | |
151 | template<> | |
ca6c4418 | 152 | struct __is_void<void> |
725dc051 | 153 | { |
4d73fac9 | 154 | enum { __value = 1 }; |
c0736a9d | 155 | typedef __true_type __type; |
725dc051 | 156 | }; |
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157 | |
158 | // | |
159 | // Integer types | |
160 | // | |
161 | template<typename _Tp> | |
162 | struct __is_integer | |
163 | { | |
4d73fac9 | 164 | enum { __value = 0 }; |
c0736a9d | 165 | typedef __false_type __type; |
725dc051 BK |
166 | }; |
167 | ||
168 | // Thirteen specializations (yes there are eleven standard integer | |
169 | // types; 'long long' and 'unsigned long long' are supported as | |
170 | // extensions) | |
171 | template<> | |
172 | struct __is_integer<bool> | |
173 | { | |
4d73fac9 | 174 | enum { __value = 1 }; |
c0736a9d | 175 | typedef __true_type __type; |
725dc051 | 176 | }; |
ed6814f7 | 177 | |
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178 | template<> |
179 | struct __is_integer<char> | |
180 | { | |
4d73fac9 | 181 | enum { __value = 1 }; |
c0736a9d | 182 | typedef __true_type __type; |
725dc051 BK |
183 | }; |
184 | ||
185 | template<> | |
186 | struct __is_integer<signed char> | |
187 | { | |
4d73fac9 | 188 | enum { __value = 1 }; |
c0736a9d | 189 | typedef __true_type __type; |
725dc051 | 190 | }; |
ed6814f7 | 191 | |
725dc051 | 192 | template<> |
ff89096a | 193 | struct __is_integer<unsigned char> |
725dc051 | 194 | { |
4d73fac9 | 195 | enum { __value = 1 }; |
c0736a9d | 196 | typedef __true_type __type; |
725dc051 | 197 | }; |
725dc051 | 198 | |
3d7c150e | 199 | # ifdef _GLIBCXX_USE_WCHAR_T |
725dc051 | 200 | template<> |
ff89096a | 201 | struct __is_integer<wchar_t> |
725dc051 | 202 | { |
4d73fac9 | 203 | enum { __value = 1 }; |
c0736a9d | 204 | typedef __true_type __type; |
725dc051 | 205 | }; |
725dc051 | 206 | # endif |
ed6814f7 | 207 | |
725dc051 | 208 | template<> |
ff89096a | 209 | struct __is_integer<short> |
725dc051 | 210 | { |
4d73fac9 | 211 | enum { __value = 1 }; |
c0736a9d | 212 | typedef __true_type __type; |
725dc051 | 213 | }; |
725dc051 BK |
214 | |
215 | template<> | |
ff89096a | 216 | struct __is_integer<unsigned short> |
725dc051 | 217 | { |
4d73fac9 | 218 | enum { __value = 1 }; |
c0736a9d | 219 | typedef __true_type __type; |
725dc051 | 220 | }; |
725dc051 BK |
221 | |
222 | template<> | |
ff89096a | 223 | struct __is_integer<int> |
725dc051 | 224 | { |
4d73fac9 | 225 | enum { __value = 1 }; |
c0736a9d | 226 | typedef __true_type __type; |
725dc051 | 227 | }; |
725dc051 BK |
228 | |
229 | template<> | |
ff89096a | 230 | struct __is_integer<unsigned int> |
725dc051 | 231 | { |
4d73fac9 | 232 | enum { __value = 1 }; |
c0736a9d | 233 | typedef __true_type __type; |
725dc051 | 234 | }; |
725dc051 BK |
235 | |
236 | template<> | |
ff89096a | 237 | struct __is_integer<long> |
725dc051 | 238 | { |
4d73fac9 | 239 | enum { __value = 1 }; |
c0736a9d | 240 | typedef __true_type __type; |
725dc051 | 241 | }; |
725dc051 BK |
242 | |
243 | template<> | |
ff89096a | 244 | struct __is_integer<unsigned long> |
725dc051 | 245 | { |
4d73fac9 | 246 | enum { __value = 1 }; |
c0736a9d | 247 | typedef __true_type __type; |
725dc051 | 248 | }; |
725dc051 | 249 | |
725dc051 | 250 | template<> |
ff89096a | 251 | struct __is_integer<long long> |
725dc051 | 252 | { |
4d73fac9 | 253 | enum { __value = 1 }; |
c0736a9d | 254 | typedef __true_type __type; |
725dc051 | 255 | }; |
725dc051 BK |
256 | |
257 | template<> | |
ff89096a | 258 | struct __is_integer<unsigned long long> |
725dc051 | 259 | { |
4d73fac9 | 260 | enum { __value = 1 }; |
c0736a9d | 261 | typedef __true_type __type; |
725dc051 | 262 | }; |
725dc051 BK |
263 | |
264 | // | |
265 | // Floating point types | |
266 | // | |
267 | template<typename _Tp> | |
ff89096a | 268 | struct __is_floating |
725dc051 | 269 | { |
4d73fac9 | 270 | enum { __value = 0 }; |
c0736a9d | 271 | typedef __false_type __type; |
725dc051 | 272 | }; |
725dc051 BK |
273 | |
274 | // three specializations (float, double and 'long double') | |
275 | template<> | |
ff89096a | 276 | struct __is_floating<float> |
725dc051 | 277 | { |
4d73fac9 | 278 | enum { __value = 1 }; |
c0736a9d | 279 | typedef __true_type __type; |
725dc051 | 280 | }; |
725dc051 BK |
281 | |
282 | template<> | |
ff89096a | 283 | struct __is_floating<double> |
725dc051 | 284 | { |
4d73fac9 | 285 | enum { __value = 1 }; |
c0736a9d | 286 | typedef __true_type __type; |
725dc051 | 287 | }; |
725dc051 BK |
288 | |
289 | template<> | |
ff89096a | 290 | struct __is_floating<long double> |
725dc051 | 291 | { |
4d73fac9 | 292 | enum { __value = 1 }; |
c0736a9d | 293 | typedef __true_type __type; |
725dc051 | 294 | }; |
725dc051 | 295 | |
badd64ad PC |
296 | // |
297 | // Pointer types | |
298 | // | |
299 | template<typename _Tp> | |
300 | struct __is_pointer | |
301 | { | |
4d73fac9 | 302 | enum { __value = 0 }; |
c0736a9d | 303 | typedef __false_type __type; |
badd64ad PC |
304 | }; |
305 | ||
306 | template<typename _Tp> | |
307 | struct __is_pointer<_Tp*> | |
308 | { | |
4d73fac9 | 309 | enum { __value = 1 }; |
c0736a9d | 310 | typedef __true_type __type; |
5e91e92e PC |
311 | }; |
312 | ||
313 | // | |
314 | // Normal iterator type | |
315 | // | |
316 | template<typename _Tp> | |
317 | struct __is_normal_iterator | |
318 | { | |
4d73fac9 | 319 | enum { __value = 0 }; |
c0736a9d | 320 | typedef __false_type __type; |
5e91e92e PC |
321 | }; |
322 | ||
323 | template<typename _Iterator, typename _Container> | |
324 | struct __is_normal_iterator< __gnu_cxx::__normal_iterator<_Iterator, | |
325 | _Container> > | |
326 | { | |
4d73fac9 | 327 | enum { __value = 1 }; |
c0736a9d | 328 | typedef __true_type __type; |
badd64ad PC |
329 | }; |
330 | ||
725dc051 BK |
331 | // |
332 | // An arithmetic type is an integer type or a floating point type | |
333 | // | |
334 | template<typename _Tp> | |
ff89096a | 335 | struct __is_arithmetic |
c0736a9d PC |
336 | : public __traitor<__is_integer<_Tp>, __is_floating<_Tp> > |
337 | { }; | |
338 | ||
725dc051 BK |
339 | // |
340 | // A fundamental type is `void' or and arithmetic type | |
341 | // | |
342 | template<typename _Tp> | |
ff89096a | 343 | struct __is_fundamental |
c0736a9d PC |
344 | : public __traitor<__is_void<_Tp>, __is_arithmetic<_Tp> > |
345 | { }; | |
725dc051 | 346 | |
badd64ad | 347 | // |
67dd4a93 | 348 | // A scalar type is an arithmetic type or a pointer type |
badd64ad PC |
349 | // |
350 | template<typename _Tp> | |
67dd4a93 | 351 | struct __is_scalar |
c0736a9d PC |
352 | : public __traitor<__is_arithmetic<_Tp>, __is_pointer<_Tp> > |
353 | { }; | |
badd64ad | 354 | |
725dc051 BK |
355 | // |
356 | // For the immediate use, the following is a good approximation | |
357 | // | |
358 | template<typename _Tp> | |
ff89096a | 359 | struct __is_pod |
725dc051 | 360 | { |
ff89096a PC |
361 | enum |
362 | { | |
4d73fac9 | 363 | __value = (sizeof(__gnu_internal::__test_type<_Tp>(0)) |
ff89096a PC |
364 | != sizeof(__gnu_internal::__one)) |
365 | }; | |
725dc051 | 366 | }; |
725dc051 | 367 | |
7697e6c6 PC |
368 | // |
369 | // A stripped-down version of std::tr1::is_empty | |
370 | // | |
371 | template<typename _Tp> | |
372 | struct __is_empty | |
373 | { | |
374 | private: | |
375 | template<typename> | |
376 | struct __first { }; | |
377 | template<typename _Up> | |
378 | struct __second | |
379 | : public _Up { }; | |
380 | ||
381 | public: | |
382 | enum | |
383 | { | |
384 | __value = sizeof(__first<_Tp>) == sizeof(__second<_Tp>) | |
385 | }; | |
386 | }; | |
387 | ||
3cbc7af0 | 388 | _GLIBCXX_END_NAMESPACE |
725dc051 | 389 | |
3d7c150e | 390 | #endif //_CPP_TYPE_TRAITS_H |