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

   1 // Character Traits for use by standard string and iostream -*- C++ -*-
   2
   3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
   4 // 2006, 2007
   5 // Free Software Foundation, Inc.
   6 //
   7 // This file is part of the GNU ISO C++ Library.  This library is free
   8 // software; you can redistribute it and/or modify it under the
   9 // terms of the GNU General Public License as published by the
  10 // Free Software Foundation; either version 2, or (at your option)
  11 // any later version.
  12
  13 // This library is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License along
  19 // with this library; see the file COPYING.  If not, write to the Free
  20 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  21 // USA.
  22
  23 // As a special exception, you may use this file as part of a free software
  24 // library without restriction.  Specifically, if other files instantiate
  25 // templates or use macros or inline functions from this file, or you compile
  26 // this file and link it with other files to produce an executable, this
  27 // file does not by itself cause the resulting executable to be covered by
  28 // the GNU General Public License.  This exception does not however
  29 // invalidate any other reasons why the executable file might be covered by
  30 // the GNU General Public License.
  31
  32 /** @file char_traits.h
  33  *  This is an internal header file, included by other library headers.
  34  *  You should not attempt to use it directly.
  35  */
  36
  37 //
  38 // ISO C++ 14882: 21  Strings library
  39 //
  40
  41 #ifndef _CHAR_TRAITS_H
  42 #define _CHAR_TRAITS_H 1
  43
  44 #pragma GCC system_header
  45
  46 #include <bits/algorithmfwd.h>   // std::copy, std::fill_n
  47 #include <bits/postypes.h>      // For streampos
  48 #include <cstdio>               // For EOF
  49 #include <cwchar>               // For WEOF, wmemmove, wmemset, etc.
  50
  51 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
  52
  53   /**
  54    *  @brief  Mapping from character type to associated types.
  55    *
  56    *  @note This is an implementation class for the generic version
  57    *  of char_traits.  It defines int_type, off_type, pos_type, and
  58    *  state_type.  By default these are unsigned long, streamoff,
  59    *  streampos, and mbstate_t.  Users who need a different set of
  60    *  types, but who don't need to change the definitions of any function
  61    *  defined in char_traits, can specialize __gnu_cxx::_Char_types
  62    *  while leaving __gnu_cxx::char_traits alone. */
  63   template<typename _CharT>
  64     struct _Char_types
  65     {
  66       typedef unsigned long   int_type;
  67       typedef std::streampos  pos_type;
  68       typedef std::streamoff  off_type;
  69       typedef std::mbstate_t  state_type;
  70     };
  71
  72
  73   /**
  74    *  @brief  Base class used to implement std::char_traits.
  75    *
  76    *  @note For any given actual character type, this definition is
  77    *  probably wrong.  (Most of the member functions are likely to be
  78    *  right, but the int_type and state_type typedefs, and the eof()
  79    *  member function, are likely to be wrong.)  The reason this class
  80    *  exists is so users can specialize it.  Classes in namespace std
  81    *  may not be specialized for fundamentl types, but classes in
  82    *  namespace __gnu_cxx may be.
  83    *
  84    *  See http://gcc.gnu.org/onlinedocs/libstdc++/21_strings/howto.html#5
  85    *  for advice on how to make use of this class for "unusual" character
  86    *  types. Also, check out include/ext/pod_char_traits.h.
  87    */
  88   template<typename _CharT>
  89     struct char_traits
  90     {
  91       typedef _CharT                                    char_type;
  92       typedef typename _Char_types<_CharT>::int_type    int_type;
  93       typedef typename _Char_types<_CharT>::pos_type    pos_type;
  94       typedef typename _Char_types<_CharT>::off_type    off_type;
  95       typedef typename _Char_types<_CharT>::state_type  state_type;
  96
  97       static void
  98       assign(char_type& __c1, const char_type& __c2)
  99       { __c1 = __c2; }
 100
 101       static bool
 102       eq(const char_type& __c1, const char_type& __c2)
 103       { return __c1 == __c2; }
 104
 105       static bool
 106       lt(const char_type& __c1, const char_type& __c2)
 107       { return __c1 < __c2; }
 108
 109       static int
 110       compare(const char_type* __s1, const char_type* __s2, std::size_t __n);
 111
 112       static std::size_t
 113       length(const char_type* __s);
 114
 115       static const char_type*
 116       find(const char_type* __s, std::size_t __n, const char_type& __a);
 117
 118       static char_type*
 119       move(char_type* __s1, const char_type* __s2, std::size_t __n);
 120
 121       static char_type*
 122       copy(char_type* __s1, const char_type* __s2, std::size_t __n);
 123
 124       static char_type*
 125       assign(char_type* __s, std::size_t __n, char_type __a);
 126
 127       static char_type
 128       to_char_type(const int_type& __c)
 129       { return static_cast<char_type>(__c); }
 130
 131       static int_type
 132       to_int_type(const char_type& __c)
 133       { return static_cast<int_type>(__c); }
 134
 135       static bool
 136       eq_int_type(const int_type& __c1, const int_type& __c2)
 137       { return __c1 == __c2; }
 138
 139       static int_type
 140       eof()
 141       { return static_cast<int_type>(EOF); }
 142
 143       static int_type
 144       not_eof(const int_type& __c)
 145       { return !eq_int_type(__c, eof()) ? __c : to_int_type(char_type()); }
 146     };
 147
 148   template<typename _CharT>
 149     int
 150     char_traits<_CharT>::
 151     compare(const char_type* __s1, const char_type* __s2, std::size_t __n)
 152     {
 153       for (std::size_t __i = 0; __i < __n; ++__i)
 154         if (lt(__s1[__i], __s2[__i]))
 155           return -1;
 156         else if (lt(__s2[__i], __s1[__i]))
 157           return 1;
 158       return 0;
 159     }
 160
 161   template<typename _CharT>
 162     std::size_t
 163     char_traits<_CharT>::
 164     length(const char_type* __p)
 165     {
 166       std::size_t __i = 0;
 167       while (!eq(__p[__i], char_type()))
 168         ++__i;
 169       return __i;
 170     }
 171
 172   template<typename _CharT>
 173     const typename char_traits<_CharT>::char_type*
 174     char_traits<_CharT>::
 175     find(const char_type* __s, std::size_t __n, const char_type& __a)
 176     {
 177       for (std::size_t __i = 0; __i < __n; ++__i)
 178         if (eq(__s[__i], __a))
 179           return __s + __i;
 180       return 0;
 181     }
 182
 183   template<typename _CharT>
 184     typename char_traits<_CharT>::char_type*
 185     char_traits<_CharT>::
 186     move(char_type* __s1, const char_type* __s2, std::size_t __n)
 187     {
 188       return static_cast<_CharT*>(__builtin_memmove(__s1, __s2,
 189                                                     __n * sizeof(char_type)));
 190     }
 191
 192   template<typename _CharT>
 193     typename char_traits<_CharT>::char_type*
 194     char_traits<_CharT>::
 195     copy(char_type* __s1, const char_type* __s2, std::size_t __n)
 196     {
 197       // NB: Inline std::copy so no recursive dependencies.
 198       std::copy(__s2, __s2 + __n, __s1);
 199       return __s1;
 200     }
 201
 202   template<typename _CharT>
 203     typename char_traits<_CharT>::char_type*
 204     char_traits<_CharT>::
 205     assign(char_type* __s, std::size_t __n, char_type __a)
 206     {
 207       // NB: Inline std::fill_n so no recursive dependencies.
 208       std::fill_n(__s, __n, __a);
 209       return __s;
 210     }
 211
 212 _GLIBCXX_END_NAMESPACE
 213
 214 _GLIBCXX_BEGIN_NAMESPACE(std)
 215
 216   // 21.1
 217   /**
 218    *  @brief  Basis for explicit traits specializations.
 219    *
 220    *  @note  For any given actual character type, this definition is
 221    *  probably wrong.  Since this is just a thin wrapper around
 222    *  __gnu_cxx::char_traits, it is possible to achieve a more
 223    *  appropriate definition by specializing __gnu_cxx::char_traits.
 224    *
 225    *  See http://gcc.gnu.org/onlinedocs/libstdc++/21_strings/howto.html#5
 226    *  for advice on how to make use of this class for "unusual" character
 227    *  types. Also, check out include/ext/pod_char_traits.h.
 228   */
 229   template<class _CharT>
 230     struct char_traits : public __gnu_cxx::char_traits<_CharT>
 231     { };
 232
 233
 234   /// @brief  21.1.3.1  char_traits specializations
 235   template<>
 236     struct char_traits<char>
 237     {
 238       typedef char              char_type;
 239       typedef int               int_type;
 240       typedef streampos         pos_type;
 241       typedef streamoff         off_type;
 242       typedef mbstate_t         state_type;
 243
 244       static void
 245       assign(char_type& __c1, const char_type& __c2)
 246       { __c1 = __c2; }
 247
 248       static bool
 249       eq(const char_type& __c1, const char_type& __c2)
 250       { return __c1 == __c2; }
 251
 252       static bool
 253       lt(const char_type& __c1, const char_type& __c2)
 254       { return __c1 < __c2; }
 255
 256       static int
 257       compare(const char_type* __s1, const char_type* __s2, size_t __n)
 258       { return __builtin_memcmp(__s1, __s2, __n); }
 259
 260       static size_t
 261       length(const char_type* __s)
 262       { return __builtin_strlen(__s); }
 263
 264       static const char_type*
 265       find(const char_type* __s, size_t __n, const char_type& __a)
 266       { return static_cast<const char_type*>(__builtin_memchr(__s, __a, __n)); }
 267
 268       static char_type*
 269       move(char_type* __s1, const char_type* __s2, size_t __n)
 270       { return static_cast<char_type*>(__builtin_memmove(__s1, __s2, __n)); }
 271
 272       static char_type*
 273       copy(char_type* __s1, const char_type* __s2, size_t __n)
 274       { return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n)); }
 275
 276       static char_type*
 277       assign(char_type* __s, size_t __n, char_type __a)
 278       { return static_cast<char_type*>(__builtin_memset(__s, __a, __n)); }
 279
 280       static char_type
 281       to_char_type(const int_type& __c)
 282       { return static_cast<char_type>(__c); }
 283
 284       // To keep both the byte 0xff and the eof symbol 0xffffffff
 285       // from ending up as 0xffffffff.
 286       static int_type
 287       to_int_type(const char_type& __c)
 288       { return static_cast<int_type>(static_cast<unsigned char>(__c)); }
 289
 290       static bool
 291       eq_int_type(const int_type& __c1, const int_type& __c2)
 292       { return __c1 == __c2; }
 293
 294       static int_type
 295       eof() { return static_cast<int_type>(EOF); }
 296
 297       static int_type
 298       not_eof(const int_type& __c)
 299       { return (__c == eof()) ? 0 : __c; }
 300   };
 301
 302
 303 #ifdef _GLIBCXX_USE_WCHAR_T
 304   /// @brief  21.1.3.2  char_traits specializations
 305   template<>
 306     struct char_traits<wchar_t>
 307     {
 308       typedef wchar_t           char_type;
 309       typedef wint_t            int_type;
 310       typedef streamoff         off_type;
 311       typedef wstreampos        pos_type;
 312       typedef mbstate_t         state_type;
 313
 314       static void
 315       assign(char_type& __c1, const char_type& __c2)
 316       { __c1 = __c2; }
 317
 318       static bool
 319       eq(const char_type& __c1, const char_type& __c2)
 320       { return __c1 == __c2; }
 321
 322       static bool
 323       lt(const char_type& __c1, const char_type& __c2)
 324       { return __c1 < __c2; }
 325
 326       static int
 327       compare(const char_type* __s1, const char_type* __s2, size_t __n)
 328       { return wmemcmp(__s1, __s2, __n); }
 329
 330       static size_t
 331       length(const char_type* __s)
 332       { return wcslen(__s); }
 333
 334       static const char_type*
 335       find(const char_type* __s, size_t __n, const char_type& __a)
 336       { return wmemchr(__s, __a, __n); }
 337
 338       static char_type*
 339       move(char_type* __s1, const char_type* __s2, size_t __n)
 340       { return wmemmove(__s1, __s2, __n); }
 341
 342       static char_type*
 343       copy(char_type* __s1, const char_type* __s2, size_t __n)
 344       { return wmemcpy(__s1, __s2, __n); }
 345
 346       static char_type*
 347       assign(char_type* __s, size_t __n, char_type __a)
 348       { return wmemset(__s, __a, __n); }
 349
 350       static char_type
 351       to_char_type(const int_type& __c) { return char_type(__c); }
 352
 353       static int_type
 354       to_int_type(const char_type& __c) { return int_type(__c); }
 355
 356       static bool
 357       eq_int_type(const int_type& __c1, const int_type& __c2)
 358       { return __c1 == __c2; }
 359
 360       static int_type
 361       eof() { return static_cast<int_type>(WEOF); }
 362
 363       static int_type
 364       not_eof(const int_type& __c)
 365       { return eq_int_type(__c, eof()) ? 0 : __c; }
 366   };
 367 #endif //_GLIBCXX_USE_WCHAR_T
 368
 369 _GLIBCXX_END_NAMESPACE
 370
 371 #endif