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