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, 2008
   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/stl_algobase.h>  // std::copy, std::fill_n
  47 #include <bits/postypes.h>      // For streampos
  48 #include <cwchar>               // For WEOF, wmemmove, wmemset, etc.
  49
  50 #ifndef _GLIBCXX_STDIO_MACROS
  51 # include <cstdio>              // For EOF
  52 # define _CHAR_TRAITS_EOF EOF
  53 #else
  54 # define _CHAR_TRAITS_EOF (-1)
  55 #endif
  56
  57 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
  58
  59   /**
  60    *  @brief  Mapping from character type to associated types.
  61    *
  62    *  @note This is an implementation class for the generic version
  63    *  of char_traits.  It defines int_type, off_type, pos_type, and
  64    *  state_type.  By default these are unsigned long, streamoff,
  65    *  streampos, and mbstate_t.  Users who need a different set of
  66    *  types, but who don't need to change the definitions of any function
  67    *  defined in char_traits, can specialize __gnu_cxx::_Char_types
  68    *  while leaving __gnu_cxx::char_traits alone. */
  69   template<typename _CharT>
  70     struct _Char_types
  71     {
  72       typedef unsigned long   int_type;
  73       typedef std::streampos  pos_type;
  74       typedef std::streamoff  off_type;
  75       typedef std::mbstate_t  state_type;
  76     };
  77
  78
  79   /**
  80    *  @brief  Base class used to implement std::char_traits.
  81    *
  82    *  @note For any given actual character type, this definition is
  83    *  probably wrong.  (Most of the member functions are likely to be
  84    *  right, but the int_type and state_type typedefs, and the eof()
  85    *  member function, are likely to be wrong.)  The reason this class
  86    *  exists is so users can specialize it.  Classes in namespace std
  87    *  may not be specialized for fundamental types, but classes in
  88    *  namespace __gnu_cxx may be.
  89    *
  90    *  See http://gcc.gnu.org/onlinedocs/libstdc++/21_strings/howto.html#5
  91    *  for advice on how to make use of this class for "unusual" character
  92    *  types. Also, check out include/ext/pod_char_traits.h.
  93    */
  94   template<typename _CharT>
  95     struct char_traits
  96     {
  97       typedef _CharT                                    char_type;
  98       typedef typename _Char_types<_CharT>::int_type    int_type;
  99       typedef typename _Char_types<_CharT>::pos_type    pos_type;
 100       typedef typename _Char_types<_CharT>::off_type    off_type;
 101       typedef typename _Char_types<_CharT>::state_type  state_type;
 102
 103       static void
 104       assign(char_type& __c1, const char_type& __c2)
 105       { __c1 = __c2; }
 106
 107       static bool
 108       eq(const char_type& __c1, const char_type& __c2)
 109       { return __c1 == __c2; }
 110
 111       static bool
 112       lt(const char_type& __c1, const char_type& __c2)
 113       { return __c1 < __c2; }
 114
 115       static int
 116       compare(const char_type* __s1, const char_type* __s2, std::size_t __n);
 117
 118       static std::size_t
 119       length(const char_type* __s);
 120
 121       static const char_type*
 122       find(const char_type* __s, std::size_t __n, const char_type& __a);
 123
 124       static char_type*
 125       move(char_type* __s1, const char_type* __s2, std::size_t __n);
 126
 127       static char_type*
 128       copy(char_type* __s1, const char_type* __s2, std::size_t __n);
 129
 130       static char_type*
 131       assign(char_type* __s, std::size_t __n, char_type __a);
 132
 133       static char_type
 134       to_char_type(const int_type& __c)
 135       { return static_cast<char_type>(__c); }
 136
 137       static int_type
 138       to_int_type(const char_type& __c)
 139       { return static_cast<int_type>(__c); }
 140
 141       static bool
 142       eq_int_type(const int_type& __c1, const int_type& __c2)
 143       { return __c1 == __c2; }
 144
 145       static int_type
 146       eof()
 147       { return static_cast<int_type>(_CHAR_TRAITS_EOF); }
 148
 149       static int_type
 150       not_eof(const int_type& __c)
 151       { return !eq_int_type(__c, eof()) ? __c : to_int_type(char_type()); }
 152     };
 153
 154   template<typename _CharT>
 155     int
 156     char_traits<_CharT>::
 157     compare(const char_type* __s1, const char_type* __s2, std::size_t __n)
 158     {
 159       for (std::size_t __i = 0; __i < __n; ++__i)
 160         if (lt(__s1[__i], __s2[__i]))
 161           return -1;
 162         else if (lt(__s2[__i], __s1[__i]))
 163           return 1;
 164       return 0;
 165     }
 166
 167   template<typename _CharT>
 168     std::size_t
 169     char_traits<_CharT>::
 170     length(const char_type* __p)
 171     {
 172       std::size_t __i = 0;
 173       while (!eq(__p[__i], char_type()))
 174         ++__i;
 175       return __i;
 176     }
 177
 178   template<typename _CharT>
 179     const typename char_traits<_CharT>::char_type*
 180     char_traits<_CharT>::
 181     find(const char_type* __s, std::size_t __n, const char_type& __a)
 182     {
 183       for (std::size_t __i = 0; __i < __n; ++__i)
 184         if (eq(__s[__i], __a))
 185           return __s + __i;
 186       return 0;
 187     }
 188
 189   template<typename _CharT>
 190     typename char_traits<_CharT>::char_type*
 191     char_traits<_CharT>::
 192     move(char_type* __s1, const char_type* __s2, std::size_t __n)
 193     {
 194       return static_cast<_CharT*>(__builtin_memmove(__s1, __s2,
 195                                                     __n * sizeof(char_type)));
 196     }
 197
 198   template<typename _CharT>
 199     typename char_traits<_CharT>::char_type*
 200     char_traits<_CharT>::
 201     copy(char_type* __s1, const char_type* __s2, std::size_t __n)
 202     {
 203       // NB: Inline std::copy so no recursive dependencies.
 204       std::copy(__s2, __s2 + __n, __s1);
 205       return __s1;
 206     }
 207
 208   template<typename _CharT>
 209     typename char_traits<_CharT>::char_type*
 210     char_traits<_CharT>::
 211     assign(char_type* __s, std::size_t __n, char_type __a)
 212     {
 213       // NB: Inline std::fill_n so no recursive dependencies.
 214       std::fill_n(__s, __n, __a);
 215       return __s;
 216     }
 217
 218 _GLIBCXX_END_NAMESPACE
 219
 220 _GLIBCXX_BEGIN_NAMESPACE(std)
 221
 222   // 21.1
 223   /**
 224    *  @brief  Basis for explicit traits specializations.
 225    *
 226    *  @note  For any given actual character type, this definition is
 227    *  probably wrong.  Since this is just a thin wrapper around
 228    *  __gnu_cxx::char_traits, it is possible to achieve a more
 229    *  appropriate definition by specializing __gnu_cxx::char_traits.
 230    *
 231    *  See http://gcc.gnu.org/onlinedocs/libstdc++/21_strings/howto.html#5
 232    *  for advice on how to make use of this class for "unusual" character
 233    *  types. Also, check out include/ext/pod_char_traits.h.
 234   */
 235   template<class _CharT>
 236     struct char_traits : public __gnu_cxx::char_traits<_CharT>
 237     { };
 238
 239
 240   /// 21.1.3.1  char_traits specializations
 241   template<>
 242     struct char_traits<char>
 243     {
 244       typedef char              char_type;
 245       typedef int               int_type;
 246       typedef streampos         pos_type;
 247       typedef streamoff         off_type;
 248       typedef mbstate_t         state_type;
 249
 250       static void
 251       assign(char_type& __c1, const char_type& __c2)
 252       { __c1 = __c2; }
 253
 254       static bool
 255       eq(const char_type& __c1, const char_type& __c2)
 256       { return __c1 == __c2; }
 257
 258       static bool
 259       lt(const char_type& __c1, const char_type& __c2)
 260       { return __c1 < __c2; }
 261
 262       static int
 263       compare(const char_type* __s1, const char_type* __s2, size_t __n)
 264       { return __builtin_memcmp(__s1, __s2, __n); }
 265
 266       static size_t
 267       length(const char_type* __s)
 268       { return __builtin_strlen(__s); }
 269
 270       static const char_type*
 271       find(const char_type* __s, size_t __n, const char_type& __a)
 272       { return static_cast<const char_type*>(__builtin_memchr(__s, __a, __n)); }
 273
 274       static char_type*
 275       move(char_type* __s1, const char_type* __s2, size_t __n)
 276       { return static_cast<char_type*>(__builtin_memmove(__s1, __s2, __n)); }
 277
 278       static char_type*
 279       copy(char_type* __s1, const char_type* __s2, size_t __n)
 280       { return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n)); }
 281
 282       static char_type*
 283       assign(char_type* __s, size_t __n, char_type __a)
 284       { return static_cast<char_type*>(__builtin_memset(__s, __a, __n)); }
 285
 286       static char_type
 287       to_char_type(const int_type& __c)
 288       { return static_cast<char_type>(__c); }
 289
 290       // To keep both the byte 0xff and the eof symbol 0xffffffff
 291       // from ending up as 0xffffffff.
 292       static int_type
 293       to_int_type(const char_type& __c)
 294       { return static_cast<int_type>(static_cast<unsigned char>(__c)); }
 295
 296       static bool
 297       eq_int_type(const int_type& __c1, const int_type& __c2)
 298       { return __c1 == __c2; }
 299
 300       static int_type
 301       eof() { return static_cast<int_type>(_CHAR_TRAITS_EOF); }
 302
 303       static int_type
 304       not_eof(const int_type& __c)
 305       { return (__c == eof()) ? 0 : __c; }
 306   };
 307
 308
 309 #ifdef _GLIBCXX_USE_WCHAR_T
 310   /// 21.1.3.2  char_traits specializations
 311   template<>
 312     struct char_traits<wchar_t>
 313     {
 314       typedef wchar_t           char_type;
 315       typedef wint_t            int_type;
 316       typedef streamoff         off_type;
 317       typedef wstreampos        pos_type;
 318       typedef mbstate_t         state_type;
 319
 320       static void
 321       assign(char_type& __c1, const char_type& __c2)
 322       { __c1 = __c2; }
 323
 324       static bool
 325       eq(const char_type& __c1, const char_type& __c2)
 326       { return __c1 == __c2; }
 327
 328       static bool
 329       lt(const char_type& __c1, const char_type& __c2)
 330       { return __c1 < __c2; }
 331
 332       static int
 333       compare(const char_type* __s1, const char_type* __s2, size_t __n)
 334       { return wmemcmp(__s1, __s2, __n); }
 335
 336       static size_t
 337       length(const char_type* __s)
 338       { return wcslen(__s); }
 339
 340       static const char_type*
 341       find(const char_type* __s, size_t __n, const char_type& __a)
 342       { return wmemchr(__s, __a, __n); }
 343
 344       static char_type*
 345       move(char_type* __s1, const char_type* __s2, size_t __n)
 346       { return wmemmove(__s1, __s2, __n); }
 347
 348       static char_type*
 349       copy(char_type* __s1, const char_type* __s2, size_t __n)
 350       { return wmemcpy(__s1, __s2, __n); }
 351
 352       static char_type*
 353       assign(char_type* __s, size_t __n, char_type __a)
 354       { return wmemset(__s, __a, __n); }
 355
 356       static char_type
 357       to_char_type(const int_type& __c) { return char_type(__c); }
 358
 359       static int_type
 360       to_int_type(const char_type& __c) { return int_type(__c); }
 361
 362       static bool
 363       eq_int_type(const int_type& __c1, const int_type& __c2)
 364       { return __c1 == __c2; }
 365
 366       static int_type
 367       eof() { return static_cast<int_type>(WEOF); }
 368
 369       static int_type
 370       not_eof(const int_type& __c)
 371       { return eq_int_type(__c, eof()) ? 0 : __c; }
 372   };
 373 #endif //_GLIBCXX_USE_WCHAR_T
 374
 375 _GLIBCXX_END_NAMESPACE
 376
 377 #undef _CHAR_TRAITS_EOF
 378
 379 #endif