headers/cpp/type_traits.h

   1 /*
   2  *
   3  * Copyright (c) 1997
   4  * Silicon Graphics Computer Systems, Inc.
   5  *
   6  * Permission to use, copy, modify, distribute and sell this software
   7  * and its documentation for any purpose is hereby granted without fee,
   8  * provided that the above copyright notice appear in all copies and
   9  * that both that copyright notice and this permission notice appear
  10  * in supporting documentation.  Silicon Graphics makes no
  11  * representations about the suitability of this software for any
  12  * purpose.  It is provided "as is" without express or implied warranty.
  13  */
  14
  15 #ifndef __TYPE_TRAITS_H
  16 #define __TYPE_TRAITS_H
  17
  18 #ifndef __STL_CONFIG_H
  19 #include <stl_config.h>
  20 #endif
  21
  22 /*
  23 This header file provides a framework for allowing compile time dispatch
  24 based on type attributes. This is useful when writing template code.
  25 For example, when making a copy of an array of an unknown type, it helps
  26 to know if the type has a trivial copy constructor or not, to help decide
  27 if a memcpy can be used.
  28
  29 The class template __type_traits provides a series of typedefs each of
  30 which is either __true_type or __false_type. The argument to
  31 __type_traits can be any type. The typedefs within this template will
  32 attain their correct values by one of these means:
  33     1. The general instantiation contain conservative values which work
  34        for all types.
  35     2. Specializations may be declared to make distinctions between types.
  36     3. Some compilers (such as the Silicon Graphics N32 and N64 compilers)
  37        will automatically provide the appropriate specializations for all
  38        types.
  39
  40 EXAMPLE:
  41
  42 //Copy an array of elements which have non-trivial copy constructors
  43 template <class T> void copy(T* source, T* destination, int n, __false_type);
  44 //Copy an array of elements which have trivial copy constructors. Use memcpy.
  45 template <class T> void copy(T* source, T* destination, int n, __true_type);
  46
  47 //Copy an array of any type by using the most efficient copy mechanism
  48 template <class T> inline void copy(T* source,T* destination,int n) {
  49    copy(source, destination, n,
  50         typename __type_traits<T>::has_trivial_copy_constructor());
  51 }
  52 */
  53
  54
  55 struct __true_type {
  56 };
  57
  58 struct __false_type {
  59 };
  60
  61 template <class _Tp>
  62 struct __type_traits {
  63    typedef __true_type     this_dummy_member_must_be_first;
  64                    /* Do not remove this member. It informs a compiler which
  65                       automatically specializes __type_traits that this
  66                       __type_traits template is special. It just makes sure that
  67                       things work if an implementation is using a template
  68                       called __type_traits for something unrelated. */
  69
  70    /* The following restrictions should be observed for the sake of
  71       compilers which automatically produce type specific specializations
  72       of this class:
  73           - You may reorder the members below if you wish
  74           - You may remove any of the members below if you wish
  75           - You must not rename members without making the corresponding
  76             name change in the compiler
  77           - Members you add will be treated like regular members unless
  78             you add the appropriate support in the compiler. */
  79
  80
  81    typedef __false_type    has_trivial_default_constructor;
  82    typedef __false_type    has_trivial_copy_constructor;
  83    typedef __false_type    has_trivial_assignment_operator;
  84    typedef __false_type    has_trivial_destructor;
  85    typedef __false_type    is_POD_type;
  86 };
  87
  88
  89
  90 // Provide some specializations.  This is harmless for compilers that
  91 //  have built-in __types_traits support, and essential for compilers
  92 //  that don't.
  93
  94 #ifndef __STL_NO_BOOL
  95
  96 __STL_TEMPLATE_NULL struct __type_traits<bool> {
  97    typedef __true_type    has_trivial_default_constructor;
  98    typedef __true_type    has_trivial_copy_constructor;
  99    typedef __true_type    has_trivial_assignment_operator;
 100    typedef __true_type    has_trivial_destructor;
 101    typedef __true_type    is_POD_type;
 102 };
 103
 104 #endif /* __STL_NO_BOOL */
 105
 106 __STL_TEMPLATE_NULL struct __type_traits<char> {
 107    typedef __true_type    has_trivial_default_constructor;
 108    typedef __true_type    has_trivial_copy_constructor;
 109    typedef __true_type    has_trivial_assignment_operator;
 110    typedef __true_type    has_trivial_destructor;
 111    typedef __true_type    is_POD_type;
 112 };
 113
 114 __STL_TEMPLATE_NULL struct __type_traits<signed char> {
 115    typedef __true_type    has_trivial_default_constructor;
 116    typedef __true_type    has_trivial_copy_constructor;
 117    typedef __true_type    has_trivial_assignment_operator;
 118    typedef __true_type    has_trivial_destructor;
 119    typedef __true_type    is_POD_type;
 120 };
 121
 122 __STL_TEMPLATE_NULL struct __type_traits<unsigned char> {
 123    typedef __true_type    has_trivial_default_constructor;
 124    typedef __true_type    has_trivial_copy_constructor;
 125    typedef __true_type    has_trivial_assignment_operator;
 126    typedef __true_type    has_trivial_destructor;
 127    typedef __true_type    is_POD_type;
 128 };
 129
 130 #ifdef __STL_HAS_WCHAR_T
 131
 132 __STL_TEMPLATE_NULL struct __type_traits<wchar_t> {
 133    typedef __true_type    has_trivial_default_constructor;
 134    typedef __true_type    has_trivial_copy_constructor;
 135    typedef __true_type    has_trivial_assignment_operator;
 136    typedef __true_type    has_trivial_destructor;
 137    typedef __true_type    is_POD_type;
 138 };
 139
 140 #endif /* __STL_HAS_WCHAR_T */
 141
 142 __STL_TEMPLATE_NULL struct __type_traits<short> {
 143    typedef __true_type    has_trivial_default_constructor;
 144    typedef __true_type    has_trivial_copy_constructor;
 145    typedef __true_type    has_trivial_assignment_operator;
 146    typedef __true_type    has_trivial_destructor;
 147    typedef __true_type    is_POD_type;
 148 };
 149
 150 __STL_TEMPLATE_NULL struct __type_traits<unsigned short> {
 151    typedef __true_type    has_trivial_default_constructor;
 152    typedef __true_type    has_trivial_copy_constructor;
 153    typedef __true_type    has_trivial_assignment_operator;
 154    typedef __true_type    has_trivial_destructor;
 155    typedef __true_type    is_POD_type;
 156 };
 157
 158 __STL_TEMPLATE_NULL struct __type_traits<int> {
 159    typedef __true_type    has_trivial_default_constructor;
 160    typedef __true_type    has_trivial_copy_constructor;
 161    typedef __true_type    has_trivial_assignment_operator;
 162    typedef __true_type    has_trivial_destructor;
 163    typedef __true_type    is_POD_type;
 164 };
 165
 166 __STL_TEMPLATE_NULL struct __type_traits<unsigned int> {
 167    typedef __true_type    has_trivial_default_constructor;
 168    typedef __true_type    has_trivial_copy_constructor;
 169    typedef __true_type    has_trivial_assignment_operator;
 170    typedef __true_type    has_trivial_destructor;
 171    typedef __true_type    is_POD_type;
 172 };
 173
 174 __STL_TEMPLATE_NULL struct __type_traits<long> {
 175    typedef __true_type    has_trivial_default_constructor;
 176    typedef __true_type    has_trivial_copy_constructor;
 177    typedef __true_type    has_trivial_assignment_operator;
 178    typedef __true_type    has_trivial_destructor;
 179    typedef __true_type    is_POD_type;
 180 };
 181
 182 __STL_TEMPLATE_NULL struct __type_traits<unsigned long> {
 183    typedef __true_type    has_trivial_default_constructor;
 184    typedef __true_type    has_trivial_copy_constructor;
 185    typedef __true_type    has_trivial_assignment_operator;
 186    typedef __true_type    has_trivial_destructor;
 187    typedef __true_type    is_POD_type;
 188 };
 189
 190 #ifdef __STL_LONG_LONG
 191
 192 __STL_TEMPLATE_NULL struct __type_traits<long long> {
 193    typedef __true_type    has_trivial_default_constructor;
 194    typedef __true_type    has_trivial_copy_constructor;
 195    typedef __true_type    has_trivial_assignment_operator;
 196    typedef __true_type    has_trivial_destructor;
 197    typedef __true_type    is_POD_type;
 198 };
 199
 200 __STL_TEMPLATE_NULL struct __type_traits<unsigned long long> {
 201    typedef __true_type    has_trivial_default_constructor;
 202    typedef __true_type    has_trivial_copy_constructor;
 203    typedef __true_type    has_trivial_assignment_operator;
 204    typedef __true_type    has_trivial_destructor;
 205    typedef __true_type    is_POD_type;
 206 };
 207
 208 #endif /* __STL_LONG_LONG */
 209
 210 __STL_TEMPLATE_NULL struct __type_traits<float> {
 211    typedef __true_type    has_trivial_default_constructor;
 212    typedef __true_type    has_trivial_copy_constructor;
 213    typedef __true_type    has_trivial_assignment_operator;
 214    typedef __true_type    has_trivial_destructor;
 215    typedef __true_type    is_POD_type;
 216 };
 217
 218 __STL_TEMPLATE_NULL struct __type_traits<double> {
 219    typedef __true_type    has_trivial_default_constructor;
 220    typedef __true_type    has_trivial_copy_constructor;
 221    typedef __true_type    has_trivial_assignment_operator;
 222    typedef __true_type    has_trivial_destructor;
 223    typedef __true_type    is_POD_type;
 224 };
 225
 226 __STL_TEMPLATE_NULL struct __type_traits<long double> {
 227    typedef __true_type    has_trivial_default_constructor;
 228    typedef __true_type    has_trivial_copy_constructor;
 229    typedef __true_type    has_trivial_assignment_operator;
 230    typedef __true_type    has_trivial_destructor;
 231    typedef __true_type    is_POD_type;
 232 };
 233
 234 #ifdef __STL_CLASS_PARTIAL_SPECIALIZATION
 235
 236 template <class _Tp>
 237 struct __type_traits<_Tp*> {
 238    typedef __true_type    has_trivial_default_constructor;
 239    typedef __true_type    has_trivial_copy_constructor;
 240    typedef __true_type    has_trivial_assignment_operator;
 241    typedef __true_type    has_trivial_destructor;
 242    typedef __true_type    is_POD_type;
 243 };
 244
 245 #else /* __STL_CLASS_PARTIAL_SPECIALIZATION */
 246
 247 __STL_TEMPLATE_NULL struct __type_traits<char*> {
 248    typedef __true_type    has_trivial_default_constructor;
 249    typedef __true_type    has_trivial_copy_constructor;
 250    typedef __true_type    has_trivial_assignment_operator;
 251    typedef __true_type    has_trivial_destructor;
 252    typedef __true_type    is_POD_type;
 253 };
 254
 255 __STL_TEMPLATE_NULL struct __type_traits<signed char*> {
 256    typedef __true_type    has_trivial_default_constructor;
 257    typedef __true_type    has_trivial_copy_constructor;
 258    typedef __true_type    has_trivial_assignment_operator;
 259    typedef __true_type    has_trivial_destructor;
 260    typedef __true_type    is_POD_type;
 261 };
 262
 263 __STL_TEMPLATE_NULL struct __type_traits<unsigned char*> {
 264    typedef __true_type    has_trivial_default_constructor;
 265    typedef __true_type    has_trivial_copy_constructor;
 266    typedef __true_type    has_trivial_assignment_operator;
 267    typedef __true_type    has_trivial_destructor;
 268    typedef __true_type    is_POD_type;
 269 };
 270
 271 __STL_TEMPLATE_NULL struct __type_traits<const char*> {
 272    typedef __true_type    has_trivial_default_constructor;
 273    typedef __true_type    has_trivial_copy_constructor;
 274    typedef __true_type    has_trivial_assignment_operator;
 275    typedef __true_type    has_trivial_destructor;
 276    typedef __true_type    is_POD_type;
 277 };
 278
 279 __STL_TEMPLATE_NULL struct __type_traits<const signed char*> {
 280    typedef __true_type    has_trivial_default_constructor;
 281    typedef __true_type    has_trivial_copy_constructor;
 282    typedef __true_type    has_trivial_assignment_operator;
 283    typedef __true_type    has_trivial_destructor;
 284    typedef __true_type    is_POD_type;
 285 };
 286
 287 __STL_TEMPLATE_NULL struct __type_traits<const unsigned char*> {
 288    typedef __true_type    has_trivial_default_constructor;
 289    typedef __true_type    has_trivial_copy_constructor;
 290    typedef __true_type    has_trivial_assignment_operator;
 291    typedef __true_type    has_trivial_destructor;
 292    typedef __true_type    is_POD_type;
 293 };
 294
 295 #endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */
 296
 297
 298 // The following could be written in terms of numeric_limits.
 299 // We're doing it separately to reduce the number of dependencies.
 300
 301 template <class _Tp> struct _Is_integer {
 302   typedef __false_type _Integral;
 303 };
 304
 305 #ifndef __STL_NO_BOOL
 306
 307 __STL_TEMPLATE_NULL struct _Is_integer<bool> {
 308   typedef __true_type _Integral;
 309 };
 310
 311 #endif /* __STL_NO_BOOL */
 312
 313 __STL_TEMPLATE_NULL struct _Is_integer<char> {
 314   typedef __true_type _Integral;
 315 };
 316
 317 __STL_TEMPLATE_NULL struct _Is_integer<signed char> {
 318   typedef __true_type _Integral;
 319 };
 320
 321 __STL_TEMPLATE_NULL struct _Is_integer<unsigned char> {
 322   typedef __true_type _Integral;
 323 };
 324
 325 #ifdef __STL_HAS_WCHAR_T
 326
 327 __STL_TEMPLATE_NULL struct _Is_integer<wchar_t> {
 328   typedef __true_type _Integral;
 329 };
 330
 331 #endif /* __STL_HAS_WCHAR_T */
 332
 333 __STL_TEMPLATE_NULL struct _Is_integer<short> {
 334   typedef __true_type _Integral;
 335 };
 336
 337 __STL_TEMPLATE_NULL struct _Is_integer<unsigned short> {
 338   typedef __true_type _Integral;
 339 };
 340
 341 __STL_TEMPLATE_NULL struct _Is_integer<int> {
 342   typedef __true_type _Integral;
 343 };
 344
 345 __STL_TEMPLATE_NULL struct _Is_integer<unsigned int> {
 346   typedef __true_type _Integral;
 347 };
 348
 349 __STL_TEMPLATE_NULL struct _Is_integer<long> {
 350   typedef __true_type _Integral;
 351 };
 352
 353 __STL_TEMPLATE_NULL struct _Is_integer<unsigned long> {
 354   typedef __true_type _Integral;
 355 };
 356
 357 #ifdef __STL_LONG_LONG
 358
 359 __STL_TEMPLATE_NULL struct _Is_integer<long long> {
 360   typedef __true_type _Integral;
 361 };
 362
 363 __STL_TEMPLATE_NULL struct _Is_integer<unsigned long long> {
 364   typedef __true_type _Integral;
 365 };
 366
 367 #endif /* __STL_LONG_LONG */
 368
 369 #endif /* __TYPE_TRAITS_H */
 370
 371 // Local Variables:
 372 // mode:C++
 373 // End: