libstdc++-v3/include/bits/char_traits.h

   1 // Character Traits for use by standard string and iostream -*- C++ -*-
   2
   3 // Copyright (C) 1997-2015 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library 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 bits/char_traits.h
  26  *  This is an internal header file, included by other library headers.
  27  *  Do not attempt to use it directly. @headername{string}
  28  */
  29
  30 //
  31 // ISO C++ 14882: 21  Strings library
  32 //
  33
  34 #ifndef _CHAR_TRAITS_H
  35 #define _CHAR_TRAITS_H 1
  36
  37 #pragma GCC system_header
  38
  39 #include <bits/stl_algobase.h>  // std::copy, std::fill_n
  40 #include <bits/postypes.h>      // For streampos
  41 #include <cwchar>               // For WEOF, wmemmove, wmemset, etc.
  42
  43 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
  44 {
  45 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  46
  47   /**
  48    *  @brief  Mapping from character type to associated types.
  49    *
  50    *  @note This is an implementation class for the generic version
  51    *  of char_traits.  It defines int_type, off_type, pos_type, and
  52    *  state_type.  By default these are unsigned long, streamoff,
  53    *  streampos, and mbstate_t.  Users who need a different set of
  54    *  types, but who don't need to change the definitions of any function
  55    *  defined in char_traits, can specialize __gnu_cxx::_Char_types
  56    *  while leaving __gnu_cxx::char_traits alone. */
  57   template<typename _CharT>
  58     struct _Char_types
  59     {
  60       typedef unsigned long   int_type;
  61       typedef std::streampos  pos_type;
  62       typedef std::streamoff  off_type;
  63       typedef std::mbstate_t  state_type;
  64     };
  65
  66
  67   /**
  68    *  @brief  Base class used to implement std::char_traits.
  69    *
  70    *  @note For any given actual character type, this definition is
  71    *  probably wrong.  (Most of the member functions are likely to be
  72    *  right, but the int_type and state_type typedefs, and the eof()
  73    *  member function, are likely to be wrong.)  The reason this class
  74    *  exists is so users can specialize it.  Classes in namespace std
  75    *  may not be specialized for fundamental types, but classes in
  76    *  namespace __gnu_cxx may be.
  77    *
  78    *  See https://gcc.gnu.org/onlinedocs/libstdc++/manual/strings.html#strings.string.character_types
  79    *  for advice on how to make use of this class for @a unusual character
  80    *  types. Also, check out include/ext/pod_char_traits.h.
  81    */
  82   template<typename _CharT>
  83     struct char_traits
  84     {
  85       typedef _CharT                                    char_type;
  86       typedef typename _Char_types<_CharT>::int_type    int_type;
  87       typedef typename _Char_types<_CharT>::pos_type    pos_type;
  88       typedef typename _Char_types<_CharT>::off_type    off_type;
  89       typedef typename _Char_types<_CharT>::state_type  state_type;
  90
  91       static void
  92       assign(char_type& __c1, const char_type& __c2)
  93       { __c1 = __c2; }
  94
  95       static _GLIBCXX_CONSTEXPR bool
  96       eq(const char_type& __c1, const char_type& __c2)
  97       { return __c1 == __c2; }
  98
  99       static _GLIBCXX_CONSTEXPR bool
 100       lt(const char_type& __c1, const char_type& __c2)
 101       { return __c1 < __c2; }
 102
 103       static int
 104       compare(const char_type* __s1, const char_type* __s2, std::size_t __n);
 105
 106       static std::size_t
 107       length(const char_type* __s);
 108
 109       static const char_type*
 110       find(const char_type* __s, std::size_t __n, const char_type& __a);
 111
 112       static char_type*
 113       move(char_type* __s1, const char_type* __s2, std::size_t __n);
 114
 115       static char_type*
 116       copy(char_type* __s1, const char_type* __s2, std::size_t __n);
 117
 118       static char_type*
 119       assign(char_type* __s, std::size_t __n, char_type __a);
 120
 121       static _GLIBCXX_CONSTEXPR char_type
 122       to_char_type(const int_type& __c)
 123       { return static_cast<char_type>(__c); }
 124
 125       static _GLIBCXX_CONSTEXPR int_type
 126       to_int_type(const char_type& __c)
 127       { return static_cast<int_type>(__c); }
 128
 129       static _GLIBCXX_CONSTEXPR bool
 130       eq_int_type(const int_type& __c1, const int_type& __c2)
 131       { return __c1 == __c2; }
 132
 133       static _GLIBCXX_CONSTEXPR int_type
 134       eof()
 135       { return static_cast<int_type>(_GLIBCXX_STDIO_EOF); }
 136
 137       static _GLIBCXX_CONSTEXPR int_type
 138       not_eof(const int_type& __c)
 139       { return !eq_int_type(__c, eof()) ? __c : to_int_type(char_type()); }
 140     };
 141
 142   template<typename _CharT>
 143     int
 144     char_traits<_CharT>::
 145     compare(const char_type* __s1, const char_type* __s2, std::size_t __n)
 146     {
 147       for (std::size_t __i = 0; __i < __n; ++__i)
 148         if (lt(__s1[__i], __s2[__i]))
 149           return -1;
 150         else if (lt(__s2[__i], __s1[__i]))
 151           return 1;
 152       return 0;
 153     }
 154
 155   template<typename _CharT>
 156     std::size_t
 157     char_traits<_CharT>::
 158     length(const char_type* __p)
 159     {
 160       std::size_t __i = 0;
 161       while (!eq(__p[__i], char_type()))
 162         ++__i;
 163       return __i;
 164     }
 165
 166   template<typename _CharT>
 167     const typename char_traits<_CharT>::char_type*
 168     char_traits<_CharT>::
 169     find(const char_type* __s, std::size_t __n, const char_type& __a)
 170     {
 171       for (std::size_t __i = 0; __i < __n; ++__i)
 172         if (eq(__s[__i], __a))
 173           return __s + __i;
 174       return 0;
 175     }
 176
 177   template<typename _CharT>
 178     typename char_traits<_CharT>::char_type*
 179     char_traits<_CharT>::
 180     move(char_type* __s1, const char_type* __s2, std::size_t __n)
 181     {
 182       return static_cast<_CharT*>(__builtin_memmove(__s1, __s2,
 183                                                     __n * sizeof(char_type)));
 184     }
 185
 186   template<typename _CharT>
 187     typename char_traits<_CharT>::char_type*
 188     char_traits<_CharT>::
 189     copy(char_type* __s1, const char_type* __s2, std::size_t __n)
 190     {
 191       // NB: Inline std::copy so no recursive dependencies.
 192       std::copy(__s2, __s2 + __n, __s1);
 193       return __s1;
 194     }
 195
 196   template<typename _CharT>
 197     typename char_traits<_CharT>::char_type*
 198     char_traits<_CharT>::
 199     assign(char_type* __s, std::size_t __n, char_type __a)
 200     {
 201       // NB: Inline std::fill_n so no recursive dependencies.
 202       std::fill_n(__s, __n, __a);
 203       return __s;
 204     }
 205
 206 _GLIBCXX_END_NAMESPACE_VERSION
 207 } // namespace
 208
 209 namespace std _GLIBCXX_VISIBILITY(default)
 210 {
 211 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 212
 213   // 21.1
 214   /**
 215    *  @brief  Basis for explicit traits specializations.
 216    *
 217    *  @note  For any given actual character type, this definition is
 218    *  probably wrong.  Since this is just a thin wrapper around
 219    *  __gnu_cxx::char_traits, it is possible to achieve a more
 220    *  appropriate definition by specializing __gnu_cxx::char_traits.
 221    *
 222    *  See https://gcc.gnu.org/onlinedocs/libstdc++/manual/strings.html#strings.string.character_types
 223    *  for advice on how to make use of this class for @a unusual character
 224    *  types. Also, check out include/ext/pod_char_traits.h.
 225   */
 226   template<class _CharT>
 227     struct char_traits : public __gnu_cxx::char_traits<_CharT>
 228     { };
 229
 230
 231   /// 21.1.3.1  char_traits specializations
 232   template<>
 233     struct char_traits<char>
 234     {
 235       typedef char              char_type;
 236       typedef int               int_type;
 237       typedef streampos         pos_type;
 238       typedef streamoff         off_type;
 239       typedef mbstate_t         state_type;
 240
 241       static void
 242       assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
 243       { __c1 = __c2; }
 244
 245       static _GLIBCXX_CONSTEXPR bool
 246       eq(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
 247       { return __c1 == __c2; }
 248
 249       static _GLIBCXX_CONSTEXPR bool
 250       lt(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
 251       {
 252         // LWG 467.
 253         return (static_cast<unsigned char>(__c1)
 254                 < static_cast<unsigned char>(__c2));
 255       }
 256
 257       static int
 258       compare(const char_type* __s1, const char_type* __s2, size_t __n)
 259       { return __builtin_memcmp(__s1, __s2, __n); }
 260
 261       static size_t
 262       length(const char_type* __s)
 263       { return __builtin_strlen(__s); }
 264
 265       static const char_type*
 266       find(const char_type* __s, size_t __n, const char_type& __a)
 267       { return static_cast<const char_type*>(__builtin_memchr(__s, __a, __n)); }
 268
 269       static char_type*
 270       move(char_type* __s1, const char_type* __s2, size_t __n)
 271       { return static_cast<char_type*>(__builtin_memmove(__s1, __s2, __n)); }
 272
 273       static char_type*
 274       copy(char_type* __s1, const char_type* __s2, size_t __n)
 275       { return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n)); }
 276
 277       static char_type*
 278       assign(char_type* __s, size_t __n, char_type __a)
 279       { return static_cast<char_type*>(__builtin_memset(__s, __a, __n)); }
 280
 281       static _GLIBCXX_CONSTEXPR char_type
 282       to_char_type(const int_type& __c) _GLIBCXX_NOEXCEPT
 283       { return static_cast<char_type>(__c); }
 284
 285       // To keep both the byte 0xff and the eof symbol 0xffffffff
 286       // from ending up as 0xffffffff.
 287       static _GLIBCXX_CONSTEXPR int_type
 288       to_int_type(const char_type& __c) _GLIBCXX_NOEXCEPT
 289       { return static_cast<int_type>(static_cast<unsigned char>(__c)); }
 290
 291       static _GLIBCXX_CONSTEXPR bool
 292       eq_int_type(const int_type& __c1, const int_type& __c2) _GLIBCXX_NOEXCEPT
 293       { return __c1 == __c2; }
 294
 295       static _GLIBCXX_CONSTEXPR int_type
 296       eof() _GLIBCXX_NOEXCEPT
 297       { return static_cast<int_type>(_GLIBCXX_STDIO_EOF); }
 298
 299       static _GLIBCXX_CONSTEXPR int_type
 300       not_eof(const int_type& __c) _GLIBCXX_NOEXCEPT
 301       { return (__c == eof()) ? 0 : __c; }
 302   };
 303
 304
 305 #ifdef _GLIBCXX_USE_WCHAR_T
 306   /// 21.1.3.2  char_traits specializations
 307   template<>
 308     struct char_traits<wchar_t>
 309     {
 310       typedef wchar_t           char_type;
 311       typedef wint_t            int_type;
 312       typedef streamoff         off_type;
 313       typedef wstreampos        pos_type;
 314       typedef mbstate_t         state_type;
 315
 316       static void
 317       assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
 318       { __c1 = __c2; }
 319
 320       static _GLIBCXX_CONSTEXPR bool
 321       eq(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
 322       { return __c1 == __c2; }
 323
 324       static _GLIBCXX_CONSTEXPR bool
 325       lt(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
 326       { return __c1 < __c2; }
 327
 328       static int
 329       compare(const char_type* __s1, const char_type* __s2, size_t __n)
 330       { return wmemcmp(__s1, __s2, __n); }
 331
 332       static size_t
 333       length(const char_type* __s)
 334       { return wcslen(__s); }
 335
 336       static const char_type*
 337       find(const char_type* __s, size_t __n, const char_type& __a)
 338       { return wmemchr(__s, __a, __n); }
 339
 340       static char_type*
 341       move(char_type* __s1, const char_type* __s2, size_t __n)
 342       { return wmemmove(__s1, __s2, __n); }
 343
 344       static char_type*
 345       copy(char_type* __s1, const char_type* __s2, size_t __n)
 346       { return wmemcpy(__s1, __s2, __n); }
 347
 348       static char_type*
 349       assign(char_type* __s, size_t __n, char_type __a)
 350       { return wmemset(__s, __a, __n); }
 351
 352       static _GLIBCXX_CONSTEXPR char_type
 353       to_char_type(const int_type& __c) _GLIBCXX_NOEXCEPT
 354       { return char_type(__c); }
 355
 356       static _GLIBCXX_CONSTEXPR int_type
 357       to_int_type(const char_type& __c) _GLIBCXX_NOEXCEPT
 358       { return int_type(__c); }
 359
 360       static _GLIBCXX_CONSTEXPR bool
 361       eq_int_type(const int_type& __c1, const int_type& __c2) _GLIBCXX_NOEXCEPT
 362       { return __c1 == __c2; }
 363
 364       static _GLIBCXX_CONSTEXPR int_type
 365       eof() _GLIBCXX_NOEXCEPT
 366       { return static_cast<int_type>(WEOF); }
 367
 368       static _GLIBCXX_CONSTEXPR int_type
 369       not_eof(const int_type& __c) _GLIBCXX_NOEXCEPT
 370       { return eq_int_type(__c, eof()) ? 0 : __c; }
 371   };
 372 #endif //_GLIBCXX_USE_WCHAR_T
 373
 374 _GLIBCXX_END_NAMESPACE_VERSION
 375 } // namespace
 376
 377 #if ((__cplusplus >= 201103L) \
 378      && defined(_GLIBCXX_USE_C99_STDINT_TR1))
 379
 380 #include <cstdint>
 381
 382 namespace std _GLIBCXX_VISIBILITY(default)
 383 {
 384 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 385
 386   template<>
 387     struct char_traits<char16_t>
 388     {
 389       typedef char16_t          char_type;
 390       typedef uint_least16_t    int_type;
 391       typedef streamoff         off_type;
 392       typedef u16streampos      pos_type;
 393       typedef mbstate_t         state_type;
 394
 395       static void
 396       assign(char_type& __c1, const char_type& __c2) noexcept
 397       { __c1 = __c2; }
 398
 399       static constexpr bool
 400       eq(const char_type& __c1, const char_type& __c2) noexcept
 401       { return __c1 == __c2; }
 402
 403       static constexpr bool
 404       lt(const char_type& __c1, const char_type& __c2) noexcept
 405       { return __c1 < __c2; }
 406
 407       static int
 408       compare(const char_type* __s1, const char_type* __s2, size_t __n)
 409       {
 410         for (size_t __i = 0; __i < __n; ++__i)
 411           if (lt(__s1[__i], __s2[__i]))
 412             return -1;
 413           else if (lt(__s2[__i], __s1[__i]))
 414             return 1;
 415         return 0;
 416       }
 417
 418       static size_t
 419       length(const char_type* __s)
 420       {
 421         size_t __i = 0;
 422         while (!eq(__s[__i], char_type()))
 423           ++__i;
 424         return __i;
 425       }
 426
 427       static const char_type*
 428       find(const char_type* __s, size_t __n, const char_type& __a)
 429       {
 430         for (size_t __i = 0; __i < __n; ++__i)
 431           if (eq(__s[__i], __a))
 432             return __s + __i;
 433         return 0;
 434       }
 435
 436       static char_type*
 437       move(char_type* __s1, const char_type* __s2, size_t __n)
 438       {
 439         return (static_cast<char_type*>
 440                 (__builtin_memmove(__s1, __s2, __n * sizeof(char_type))));
 441       }
 442
 443       static char_type*
 444       copy(char_type* __s1, const char_type* __s2, size_t __n)
 445       {
 446         return (static_cast<char_type*>
 447                 (__builtin_memcpy(__s1, __s2, __n * sizeof(char_type))));
 448       }
 449
 450       static char_type*
 451       assign(char_type* __s, size_t __n, char_type __a)
 452       {
 453         for (size_t __i = 0; __i < __n; ++__i)
 454           assign(__s[__i], __a);
 455         return __s;
 456       }
 457
 458       static constexpr char_type
 459       to_char_type(const int_type& __c) noexcept
 460       { return char_type(__c); }
 461
 462       static constexpr int_type
 463       to_int_type(const char_type& __c) noexcept
 464       { return int_type(__c); }
 465
 466       static constexpr bool
 467       eq_int_type(const int_type& __c1, const int_type& __c2) noexcept
 468       { return __c1 == __c2; }
 469
 470       static constexpr int_type
 471       eof() noexcept
 472       { return static_cast<int_type>(-1); }
 473
 474       static constexpr int_type
 475       not_eof(const int_type& __c) noexcept
 476       { return eq_int_type(__c, eof()) ? 0 : __c; }
 477     };
 478
 479   template<>
 480     struct char_traits<char32_t>
 481     {
 482       typedef char32_t          char_type;
 483       typedef uint_least32_t    int_type;
 484       typedef streamoff         off_type;
 485       typedef u32streampos      pos_type;
 486       typedef mbstate_t         state_type;
 487
 488       static void
 489       assign(char_type& __c1, const char_type& __c2) noexcept
 490       { __c1 = __c2; }
 491
 492       static constexpr bool
 493       eq(const char_type& __c1, const char_type& __c2) noexcept
 494       { return __c1 == __c2; }
 495
 496       static constexpr bool
 497       lt(const char_type& __c1, const char_type& __c2) noexcept
 498       { return __c1 < __c2; }
 499
 500       static int
 501       compare(const char_type* __s1, const char_type* __s2, size_t __n)
 502       {
 503         for (size_t __i = 0; __i < __n; ++__i)
 504           if (lt(__s1[__i], __s2[__i]))
 505             return -1;
 506           else if (lt(__s2[__i], __s1[__i]))
 507             return 1;
 508         return 0;
 509       }
 510
 511       static size_t
 512       length(const char_type* __s)
 513       {
 514         size_t __i = 0;
 515         while (!eq(__s[__i], char_type()))
 516           ++__i;
 517         return __i;
 518       }
 519
 520       static const char_type*
 521       find(const char_type* __s, size_t __n, const char_type& __a)
 522       {
 523         for (size_t __i = 0; __i < __n; ++__i)
 524           if (eq(__s[__i], __a))
 525             return __s + __i;
 526         return 0;
 527       }
 528
 529       static char_type*
 530       move(char_type* __s1, const char_type* __s2, size_t __n)
 531       {
 532         return (static_cast<char_type*>
 533                 (__builtin_memmove(__s1, __s2, __n * sizeof(char_type))));
 534       }
 535
 536       static char_type*
 537       copy(char_type* __s1, const char_type* __s2, size_t __n)
 538       {
 539         return (static_cast<char_type*>
 540                 (__builtin_memcpy(__s1, __s2, __n * sizeof(char_type))));
 541       }
 542
 543       static char_type*
 544       assign(char_type* __s, size_t __n, char_type __a)
 545       {
 546         for (size_t __i = 0; __i < __n; ++__i)
 547           assign(__s[__i], __a);
 548         return __s;
 549       }
 550
 551       static constexpr char_type
 552       to_char_type(const int_type& __c) noexcept
 553       { return char_type(__c); }
 554
 555       static constexpr int_type
 556       to_int_type(const char_type& __c) noexcept
 557       { return int_type(__c); }
 558
 559       static constexpr bool
 560       eq_int_type(const int_type& __c1, const int_type& __c2) noexcept
 561       { return __c1 == __c2; }
 562
 563       static constexpr int_type
 564       eof() noexcept
 565       { return static_cast<int_type>(-1); }
 566
 567       static constexpr int_type
 568       not_eof(const int_type& __c) noexcept
 569       { return eq_int_type(__c, eof()) ? 0 : __c; }
 570     };
 571
 572 _GLIBCXX_END_NAMESPACE_VERSION
 573 } // namespace
 574
 575 #endif
 576
 577 #endif // _CHAR_TRAITS_H