# char_traits.h

Go to the documentation of this file.

    00001 // Character Traits for use by standard string and iostream -*- C++ -*-
    00002
    00003 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
    00004 // Free Software Foundation, Inc.
    00005 //
    00006 // This file is part of the GNU ISO C++ Library.  This library is free
    00007 // software; you can redistribute it and/or modify it under the
    00008 // terms of the GNU General Public License as published by the
    00009 // Free Software Foundation; either version 2, or (at your option)
    00010 // any later version.
    00011
    00012 // This library is distributed in the hope that it will be useful,
    00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of
    00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    00015 // GNU General Public License for more details.
    00016
    00017 // You should have received a copy of the GNU General Public License along
    00018 // with this library; see the file COPYING.  If not, write to the Free
    00019 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
    00020 // USA.
    00021
    00022 // As a special exception, you may use this file as part of a free software
    00023 // library without restriction.  Specifically, if other files instantiate
    00024 // templates or use macros or inline functions from this file, or you compile
    00025 // this file and link it with other files to produce an executable, this
    00026 // file does not by itself cause the resulting executable to be covered by
    00027 // the GNU General Public License.  This exception does not however
    00028 // invalidate any other reasons why the executable file might be covered by
    00029 // the GNU General Public License.
    00030
    00031 //
    00032 // ISO C++ 14882: 21  Strings library
    00033 //
    00034
    00035 /** @file char_traits.h
    00036  *  This is an internal header file, included by other library headers.
    00037  *  You should not attempt to use it directly.
    00038  */
    00039
    00040 #ifndef _CHAR_TRAITS_H
    00041 #define _CHAR_TRAITS_H 1
    00042
    00043 #pragma GCC system_header
    00044
    00045 #include <cstring>            // For memmove, memset, memchr
    00046 #include <bits/stl_algobase.h>// For copy, lexicographical_compare, fill_n
    00047 #include <bits/postypes.h>    // For streampos
    00048
    00049 namespace __gnu_cxx
    00050 {
    00051   /**
    00052    *  @brief  Mapping from character type to associated types.
    00053    *
    00054    *  @note This is an implementation class for the generic version
    00055    *  of char_traits.  It defines int_type, off_type, pos_type, and
    00056    *  state_type.  By default these are unsigned long, streamoff,
    00057    *  streampos, and mbstate_t.  Users who need a different set of
    00058    *  types, but who don't need to change the definitions of any function
    00059    *  defined in char_traits, can specialize __gnu_cxx::_Char_types
    00060    *  while leaving __gnu_cxx::char_traits alone. */
    00061   template <class _CharT>
    00062     struct _Char_types
    00063     {
    00064       typedef unsigned long   int_type;
    00065       typedef std::streampos  pos_type;
    00066       typedef std::streamoff  off_type;
    00067       typedef std::mbstate_t  state_type;
    00068     };
    00069
    00070
    00071   /**
    00072    *  @brief  Base class used to implement std::char_traits.
    00073    *
    00074    *  @note For any given actual character type, this definition is
    00075    *  probably wrong.  (Most of the member functions are likely to be
    00076    *  right, but the int_type and state_type typedefs, and the eof()
    00077    *  member function, are likely to be wrong.)  The reason this class
    00078    *  exists is so users can specialize it.  Classes in namespace std
    00079    *  may not be specialized for fundamentl types, but classes in
    00080    *  namespace __gnu_cxx may be.
    00081    *
    00082    *  See http://gcc.gnu.org/onlinedocs/libstdc++/21_strings/howto.html#5
    00083    *  for advice on how to make use of this class for "unusual" character
    00084    *  types. Also, check out include/ext/pod_char_traits.h.
    00085    */
    00086   template<typename _CharT>
    00087     struct char_traits
    00088     {
    00089       typedef _CharT                                    char_type;
    00090       typedef typename _Char_types<_CharT>::int_type    int_type;
    00091       typedef typename _Char_types<_CharT>::pos_type    pos_type;
    00092       typedef typename _Char_types<_CharT>::off_type    off_type;
    00093       typedef typename _Char_types<_CharT>::state_type  state_type;
    00094
    00095       static void
    00096       assign(char_type& __c1, const char_type& __c2)
    00097       { __c1 = __c2; }
    00098
    00099       static bool
    00100       eq(const char_type& __c1, const char_type& __c2)
    00101       { return __c1 == __c2; }
    00102
    00103       static bool
    00104       lt(const char_type& __c1, const char_type& __c2)
    00105       { return __c1 < __c2; }
    00106
    00107       static int
    00108       compare(const char_type* __s1, const char_type* __s2, std::size_t __n);
    00109
    00110       static std::size_t
    00111       length(const char_type* __s);
    00112
    00113       static const char_type*
    00114       find(const char_type* __s, std::size_t __n, const char_type& __a);
    00115
    00116       static char_type*
    00117       move(char_type* __s1, const char_type* __s2, std::size_t __n);
    00118
    00119       static char_type*
    00120       copy(char_type* __s1, const char_type* __s2, std::size_t __n);
    00121
    00122       static char_type*
    00123       assign(char_type* __s, std::size_t __n, char_type __a);
    00124
    00125       static char_type
    00126       to_char_type(const int_type& __c)
    00127       { return static_cast<char_type>(__c); }
    00128
    00129       static int_type
    00130       to_int_type(const char_type& __c)
    00131       { return static_cast<int_type>(__c); }
    00132
    00133       static bool
    00134       eq_int_type(const int_type& __c1, const int_type& __c2)
    00135       { return __c1 == __c2; }
    00136
    00137       static int_type
    00138       eof()
    00139       { return static_cast<int_type>(EOF); }
    00140
    00141       static int_type
    00142       not_eof(const int_type& __c)
    00143       { return !eq_int_type(__c, eof()) ? __c : to_int_type(char_type()); }
    00144     };
    00145
    00146   template<typename _CharT>
    00147     int
    00148     char_traits<_CharT>::
    00149     compare(const char_type* __s1, const char_type* __s2, std::size_t __n)
    00150     {
    00151       for (size_t __i = 0; __i < __n; ++__i)
    00152     if (lt(__s1[__i], __s2[__i]))
    00153       return -1;
    00154     else if (lt(__s2[__i], __s1[__i]))
    00155       return 1;
    00156       return 0;
    00157     }
    00158
    00159   template<typename _CharT>
    00160     std::size_t
    00161     char_traits<_CharT>::
    00162     length(const char_type* __p)
    00163     {
    00164       std::size_t __i = 0;
    00165       while (!eq(__p[__i], char_type()))
    00166         ++__i;
    00167       return __i;
    00168     }
    00169
    00170   template<typename _CharT>
    00171     const typename char_traits<_CharT>::char_type*
    00172     char_traits<_CharT>::
    00173     find(const char_type* __s, std::size_t __n, const char_type& __a)
    00174     {
    00175       for (std::size_t __i = 0; __i < __n; ++__i)
    00176         if (eq(__s[__i], __a))
    00177           return __s + __i;
    00178       return 0;
    00179     }
    00180
    00181   template<typename _CharT>
    00182     typename char_traits<_CharT>::char_type*
    00183     char_traits<_CharT>::
    00184     move(char_type* __s1, const char_type* __s2, std::size_t __n)
    00185     {
    00186       return static_cast<_CharT*>(std::memmove(__s1, __s2,
    00187                            __n * sizeof(char_type)));
    00188     }
    00189
    00190   template<typename _CharT>
    00191     typename char_traits<_CharT>::char_type*
    00192     char_traits<_CharT>::
    00193     copy(char_type* __s1, const char_type* __s2, std::size_t __n)
    00194     {
    00195       std::copy(__s2, __s2 + __n, __s1);
    00196       return __s1;
    00197     }
    00198
    00199   template<typename _CharT>
    00200     typename char_traits<_CharT>::char_type*
    00201     char_traits<_CharT>::
    00202     assign(char_type* __s, std::size_t __n, char_type __a)
    00203     {
    00204       std::fill_n(__s, __n, __a);
    00205       return __s;
    00206     }
    00207 }
    00208
    00209 namespace std
    00210 {
    00211   // 21.1
    00212   /**
    00213    *  @brief  Basis for explicit traits specializations.
    00214    *
    00215    *  @note  For any given actual character type, this definition is
    00216    *  probably wrong.  Since this is just a thin wrapper around
    00217    *  __gnu_cxx::char_traits, it is possible to achieve a more
    00218    *  appropriate definition by specializing __gnu_cxx::char_traits.
    00219    *
    00220    *  See http://gcc.gnu.org/onlinedocs/libstdc++/21_strings/howto.html#5
    00221    *  for advice on how to make use of this class for "unusual" character
    00222    *  types. Also, check out include/ext/pod_char_traits.h.
    00223   */
    00224   template<class _CharT>
    00225     struct char_traits : public __gnu_cxx::char_traits<_CharT>
    00226     { };
    00227
    00228
    00229   /// @brief  21.1.3.1  char_traits specializations
    00230   template<>
    00231     struct char_traits<char>
    00232     {
    00233       typedef char              char_type;
    00234       typedef int               int_type;
    00235       typedef streampos         pos_type;
    00236       typedef streamoff         off_type;
    00237       typedef mbstate_t         state_type;
    00238
    00239       static void
    00240       assign(char_type& __c1, const char_type& __c2)
    00241       { __c1 = __c2; }
    00242
    00243       static bool
    00244       eq(const char_type& __c1, const char_type& __c2)
    00245       { return __c1 == __c2; }
    00246
    00247       static bool
    00248       lt(const char_type& __c1, const char_type& __c2)
    00249       { return __c1 < __c2; }
    00250
    00251       static int
    00252       compare(const char_type* __s1, const char_type* __s2, size_t __n)
    00253       { return memcmp(__s1, __s2, __n); }
    00254
    00255       static size_t
    00256       length(const char_type* __s)
    00257       { return strlen(__s); }
    00258
    00259       static const char_type*
    00260       find(const char_type* __s, size_t __n, const char_type& __a)
    00261       { return static_cast<const char_type*>(memchr(__s, __a, __n)); }
    00262
    00263       static char_type*
    00264       move(char_type* __s1, const char_type* __s2, size_t __n)
    00265       { return static_cast<char_type*>(memmove(__s1, __s2, __n)); }
    00266
    00267       static char_type*
    00268       copy(char_type* __s1, const char_type* __s2, size_t __n)
    00269       { return static_cast<char_type*>(memcpy(__s1, __s2, __n)); }
    00270
    00271       static char_type*
    00272       assign(char_type* __s, size_t __n, char_type __a)
    00273       { return static_cast<char_type*>(memset(__s, __a, __n)); }
    00274
    00275       static char_type
    00276       to_char_type(const int_type& __c)
    00277       { return static_cast<char_type>(__c); }
    00278
    00279       // To keep both the byte 0xff and the eof symbol 0xffffffff
    00280       // from ending up as 0xffffffff.
    00281       static int_type
    00282       to_int_type(const char_type& __c)
    00283       { return static_cast<int_type>(static_cast<unsigned char>(__c)); }
    00284
    00285       static bool
    00286       eq_int_type(const int_type& __c1, const int_type& __c2)
    00287       { return __c1 == __c2; }
    00288
    00289       static int_type
    00290       eof() { return static_cast<int_type>(EOF); }
    00291
    00292       static int_type
    00293       not_eof(const int_type& __c)
    00294       { return (__c == eof()) ? 0 : __c; }
    00295   };
    00296
    00297
    00298 #ifdef _GLIBCXX_USE_WCHAR_T
    00299   /// @brief  21.1.3.2  char_traits specializations
    00300   template<>
    00301     struct char_traits<wchar_t>
    00302     {
    00303       typedef wchar_t           char_type;
    00304       typedef wint_t            int_type;
    00305       typedef streamoff         off_type;
    00306       typedef wstreampos        pos_type;
    00307       typedef mbstate_t         state_type;
    00308
    00309       static void
    00310       assign(char_type& __c1, const char_type& __c2)
    00311       { __c1 = __c2; }
    00312
    00313       static bool
    00314       eq(const char_type& __c1, const char_type& __c2)
    00315       { return __c1 == __c2; }
    00316
    00317       static bool
    00318       lt(const char_type& __c1, const char_type& __c2)
    00319       { return __c1 < __c2; }
    00320
    00321       static int
    00322       compare(const char_type* __s1, const char_type* __s2, size_t __n)
    00323       { return wmemcmp(__s1, __s2, __n); }
    00324
    00325       static size_t
    00326       length(const char_type* __s)
    00327       { return wcslen(__s); }
    00328
    00329       static const char_type*
    00330       find(const char_type* __s, size_t __n, const char_type& __a)
    00331       { return wmemchr(__s, __a, __n); }
    00332
    00333       static char_type*
    00334       move(char_type* __s1, const char_type* __s2, size_t __n)
    00335       { return wmemmove(__s1, __s2, __n); }
    00336
    00337       static char_type*
    00338       copy(char_type* __s1, const char_type* __s2, size_t __n)
    00339       { return wmemcpy(__s1, __s2, __n); }
    00340
    00341       static char_type*
    00342       assign(char_type* __s, size_t __n, char_type __a)
    00343       { return wmemset(__s, __a, __n); }
    00344
    00345       static char_type
    00346       to_char_type(const int_type& __c) { return char_type(__c); }
    00347
    00348       static int_type
    00349       to_int_type(const char_type& __c) { return int_type(__c); }
    00350
    00351       static bool
    00352       eq_int_type(const int_type& __c1, const int_type& __c2)
    00353       { return __c1 == __c2; }
    00354
    00355       static int_type
    00356       eof() { return static_cast<int_type>(WEOF); }
    00357
    00358       static int_type
    00359       not_eof(const int_type& __c)
    00360       { return eq_int_type(__c, eof()) ? 0 : __c; }
    00361   };
    00362 #endif //_GLIBCXX_USE_WCHAR_T
    00363
    00364 } // namespace std
    00365
    00366 #endif