# codecvt.h

Go to the documentation of this file.

    00001 // Locale support (codecvt) -*- C++ -*-
    00002
    00003 // Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
    00004 // 2009  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 3, 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 // Under Section 7 of GPL version 3, you are granted additional
    00018 // permissions described in the GCC Runtime Library Exception, version
    00019 // 3.1, as published by the Free Software Foundation.
    00020
    00021 // You should have received a copy of the GNU General Public License and
    00022 // a copy of the GCC Runtime Library Exception along with this program;
    00023 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
    00024 // <http://www.gnu.org/licenses/>.
    00025
    00026 /** @file bits/codecvt.h
    00027  *  This is an internal header file, included by other library headers.
    00028  *  You should not attempt to use it directly.
    00029  */
    00030
    00031 //
    00032 // ISO C++ 14882: 22.2.1.5 Template class codecvt
    00033 //
    00034
    00035 // Written by Benjamin Kosnik <bkoz@redhat.com>
    00036
    00037 #ifndef _CODECVT_H
    00038 #define _CODECVT_H 1
    00039
    00040 #pragma GCC system_header
    00041
    00042 _GLIBCXX_BEGIN_NAMESPACE(std)
    00043
    00044   /// Empty base class for codecvt facet [22.2.1.5].
    00045   class codecvt_base
    00046   {
    00047   public:
    00048     enum result
    00049     {
    00050       ok,
    00051       partial,
    00052       error,
    00053       noconv
    00054     };
    00055   };
    00056
    00057   /**
    00058    *  @brief  Common base for codecvt functions.
    00059    *
    00060    *  This template class provides implementations of the public functions
    00061    *  that forward to the protected virtual functions.
    00062    *
    00063    *  This template also provides abstract stubs for the protected virtual
    00064    *  functions.
    00065   */
    00066   template<typename _InternT, typename _ExternT, typename _StateT>
    00067     class __codecvt_abstract_base
    00068     : public locale::facet, public codecvt_base
    00069     {
    00070     public:
    00071       // Types:
    00072       typedef codecvt_base::result  result;
    00073       typedef _InternT          intern_type;
    00074       typedef _ExternT          extern_type;
    00075       typedef _StateT           state_type;
    00076
    00077       // 22.2.1.5.1 codecvt members
    00078       /**
    00079        *  @brief  Convert from internal to external character set.
    00080        *
    00081        *  Converts input string of intern_type to output string of
    00082        *  extern_type.  This is analogous to wcsrtombs.  It does this by
    00083        *  calling codecvt::do_out.
    00084        *
    00085        *  The source and destination character sets are determined by the
    00086        *  facet's locale, internal and external types.
    00087        *
    00088        *  The characters in [from,from_end) are converted and written to
    00089        *  [to,to_end).  from_next and to_next are set to point to the
    00090        *  character following the last successfully converted character,
    00091        *  respectively.  If the result needed no conversion, from_next and
    00092        *  to_next are not affected.
    00093        *
    00094        *  The @a state argument should be initialized if the input is at the
    00095        *  beginning and carried from a previous call if continuing
    00096        *  conversion.  There are no guarantees about how @a state is used.
    00097        *
    00098        *  The result returned is a member of codecvt_base::result.  If
    00099        *  all the input is converted, returns codecvt_base::ok.  If no
    00100        *  conversion is necessary, returns codecvt_base::noconv.  If
    00101        *  the input ends early or there is insufficient space in the
    00102        *  output, returns codecvt_base::partial.  Otherwise the
    00103        *  conversion failed and codecvt_base::error is returned.
    00104        *
    00105        *  @param  state  Persistent conversion state data.
    00106        *  @param  from  Start of input.
    00107        *  @param  from_end  End of input.
    00108        *  @param  from_next  Returns start of unconverted data.
    00109        *  @param  to  Start of output buffer.
    00110        *  @param  to_end  End of output buffer.
    00111        *  @param  to_next  Returns start of unused output area.
    00112        *  @return  codecvt_base::result.
    00113       */
    00114       result
    00115       out(state_type& __state, const intern_type* __from,
    00116       const intern_type* __from_end, const intern_type*& __from_next,
    00117       extern_type* __to, extern_type* __to_end,
    00118       extern_type*& __to_next) const
    00119       {
    00120     return this->do_out(__state, __from, __from_end, __from_next,
    00121                 __to, __to_end, __to_next);
    00122       }
    00123
    00124       /**
    00125        *  @brief  Reset conversion state.
    00126        *
    00127        *  Writes characters to output that would restore @a state to initial
    00128        *  conditions.  The idea is that if a partial conversion occurs, then
    00129        *  the converting the characters written by this function would leave
    00130        *  the state in initial conditions, rather than partial conversion
    00131        *  state.  It does this by calling codecvt::do_unshift().
    00132        *
    00133        *  For example, if 4 external characters always converted to 1 internal
    00134        *  character, and input to in() had 6 external characters with state
    00135        *  saved, this function would write two characters to the output and
    00136        *  set the state to initialized conditions.
    00137        *
    00138        *  The source and destination character sets are determined by the
    00139        *  facet's locale, internal and external types.
    00140        *
    00141        *  The result returned is a member of codecvt_base::result.  If the
    00142        *  state could be reset and data written, returns codecvt_base::ok.  If
    00143        *  no conversion is necessary, returns codecvt_base::noconv.  If the
    00144        *  output has insufficient space, returns codecvt_base::partial.
    00145        *  Otherwise the reset failed and codecvt_base::error is returned.
    00146        *
    00147        *  @param  state  Persistent conversion state data.
    00148        *  @param  to  Start of output buffer.
    00149        *  @param  to_end  End of output buffer.
    00150        *  @param  to_next  Returns start of unused output area.
    00151        *  @return  codecvt_base::result.
    00152       */
    00153       result
    00154       unshift(state_type& __state, extern_type* __to, extern_type* __to_end,
    00155           extern_type*& __to_next) const
    00156       { return this->do_unshift(__state, __to,__to_end,__to_next); }
    00157
    00158       /**
    00159        *  @brief  Convert from external to internal character set.
    00160        *
    00161        *  Converts input string of extern_type to output string of
    00162        *  intern_type.  This is analogous to mbsrtowcs.  It does this by
    00163        *  calling codecvt::do_in.
    00164        *
    00165        *  The source and destination character sets are determined by the
    00166        *  facet's locale, internal and external types.
    00167        *
    00168        *  The characters in [from,from_end) are converted and written to
    00169        *  [to,to_end).  from_next and to_next are set to point to the
    00170        *  character following the last successfully converted character,
    00171        *  respectively.  If the result needed no conversion, from_next and
    00172        *  to_next are not affected.
    00173        *
    00174        *  The @a state argument should be initialized if the input is at the
    00175        *  beginning and carried from a previous call if continuing
    00176        *  conversion.  There are no guarantees about how @a state is used.
    00177        *
    00178        *  The result returned is a member of codecvt_base::result.  If
    00179        *  all the input is converted, returns codecvt_base::ok.  If no
    00180        *  conversion is necessary, returns codecvt_base::noconv.  If
    00181        *  the input ends early or there is insufficient space in the
    00182        *  output, returns codecvt_base::partial.  Otherwise the
    00183        *  conversion failed and codecvt_base::error is returned.
    00184        *
    00185        *  @param  state  Persistent conversion state data.
    00186        *  @param  from  Start of input.
    00187        *  @param  from_end  End of input.
    00188        *  @param  from_next  Returns start of unconverted data.
    00189        *  @param  to  Start of output buffer.
    00190        *  @param  to_end  End of output buffer.
    00191        *  @param  to_next  Returns start of unused output area.
    00192        *  @return  codecvt_base::result.
    00193       */
    00194       result
    00195       in(state_type& __state, const extern_type* __from,
    00196      const extern_type* __from_end, const extern_type*& __from_next,
    00197      intern_type* __to, intern_type* __to_end,
    00198      intern_type*& __to_next) const
    00199       {
    00200     return this->do_in(__state, __from, __from_end, __from_next,
    00201                __to, __to_end, __to_next);
    00202       }
    00203
    00204       int
    00205       encoding() const throw()
    00206       { return this->do_encoding(); }
    00207
    00208       bool
    00209       always_noconv() const throw()
    00210       { return this->do_always_noconv(); }
    00211
    00212       int
    00213       length(state_type& __state, const extern_type* __from,
    00214          const extern_type* __end, size_t __max) const
    00215       { return this->do_length(__state, __from, __end, __max); }
    00216
    00217       int
    00218       max_length() const throw()
    00219       { return this->do_max_length(); }
    00220
    00221     protected:
    00222       explicit
    00223       __codecvt_abstract_base(size_t __refs = 0) : locale::facet(__refs) { }
    00224
    00225       virtual
    00226       ~__codecvt_abstract_base() { }
    00227
    00228       /**
    00229        *  @brief  Convert from internal to external character set.
    00230        *
    00231        *  Converts input string of intern_type to output string of
    00232        *  extern_type.  This function is a hook for derived classes to change
    00233        *  the value returned.  @see out for more information.
    00234       */
    00235       virtual result
    00236       do_out(state_type& __state, const intern_type* __from,
    00237          const intern_type* __from_end, const intern_type*& __from_next,
    00238          extern_type* __to, extern_type* __to_end,
    00239          extern_type*& __to_next) const = 0;
    00240
    00241       virtual result
    00242       do_unshift(state_type& __state, extern_type* __to,
    00243          extern_type* __to_end, extern_type*& __to_next) const = 0;
    00244
    00245       virtual result
    00246       do_in(state_type& __state, const extern_type* __from,
    00247         const extern_type* __from_end, const extern_type*& __from_next,
    00248         intern_type* __to, intern_type* __to_end,
    00249         intern_type*& __to_next) const = 0;
    00250
    00251       virtual int
    00252       do_encoding() const throw() = 0;
    00253
    00254       virtual bool
    00255       do_always_noconv() const throw() = 0;
    00256
    00257       virtual int
    00258       do_length(state_type&, const extern_type* __from,
    00259         const extern_type* __end, size_t __max) const = 0;
    00260
    00261       virtual int
    00262       do_max_length() const throw() = 0;
    00263     };
    00264
    00265   /// @brief class codecvt [22.2.1.5].
    00266   /// NB: Generic, mostly useless implementation.
    00267   template<typename _InternT, typename _ExternT, typename _StateT>
    00268     class codecvt
    00269     : public __codecvt_abstract_base<_InternT, _ExternT, _StateT>
    00270     {
    00271     public:
    00272       // Types:
    00273       typedef codecvt_base::result  result;
    00274       typedef _InternT          intern_type;
    00275       typedef _ExternT          extern_type;
    00276       typedef _StateT           state_type;
    00277
    00278     protected:
    00279       __c_locale            _M_c_locale_codecvt;
    00280
    00281     public:
    00282       static locale::id         id;
    00283
    00284       explicit
    00285       codecvt(size_t __refs = 0)
    00286       : __codecvt_abstract_base<_InternT, _ExternT, _StateT> (__refs) { }
    00287
    00288       explicit
    00289       codecvt(__c_locale __cloc, size_t __refs = 0);
    00290
    00291     protected:
    00292       virtual
    00293       ~codecvt() { }
    00294
    00295       virtual result
    00296       do_out(state_type& __state, const intern_type* __from,
    00297          const intern_type* __from_end, const intern_type*& __from_next,
    00298          extern_type* __to, extern_type* __to_end,
    00299          extern_type*& __to_next) const;
    00300
    00301       virtual result
    00302       do_unshift(state_type& __state, extern_type* __to,
    00303          extern_type* __to_end, extern_type*& __to_next) const;
    00304
    00305       virtual result
    00306       do_in(state_type& __state, const extern_type* __from,
    00307         const extern_type* __from_end, const extern_type*& __from_next,
    00308         intern_type* __to, intern_type* __to_end,
    00309         intern_type*& __to_next) const;
    00310
    00311       virtual int
    00312       do_encoding() const throw();
    00313
    00314       virtual bool
    00315       do_always_noconv() const throw();
    00316
    00317       virtual int
    00318       do_length(state_type&, const extern_type* __from,
    00319         const extern_type* __end, size_t __max) const;
    00320
    00321       virtual int
    00322       do_max_length() const throw();
    00323     };
    00324
    00325   template<typename _InternT, typename _ExternT, typename _StateT>
    00326     locale::id codecvt<_InternT, _ExternT, _StateT>::id;
    00327
    00328   /// class codecvt<char, char, mbstate_t> specialization.
    00329   template<>
    00330     class codecvt<char, char, mbstate_t>
    00331     : public __codecvt_abstract_base<char, char, mbstate_t>
    00332     {
    00333     public:
    00334       // Types:
    00335       typedef char          intern_type;
    00336       typedef char          extern_type;
    00337       typedef mbstate_t         state_type;
    00338
    00339     protected:
    00340       __c_locale            _M_c_locale_codecvt;
    00341
    00342     public:
    00343       static locale::id id;
    00344
    00345       explicit
    00346       codecvt(size_t __refs = 0);
    00347
    00348       explicit
    00349       codecvt(__c_locale __cloc, size_t __refs = 0);
    00350
    00351     protected:
    00352       virtual
    00353       ~codecvt();
    00354
    00355       virtual result
    00356       do_out(state_type& __state, const intern_type* __from,
    00357          const intern_type* __from_end, const intern_type*& __from_next,
    00358          extern_type* __to, extern_type* __to_end,
    00359          extern_type*& __to_next) const;
    00360
    00361       virtual result
    00362       do_unshift(state_type& __state, extern_type* __to,
    00363          extern_type* __to_end, extern_type*& __to_next) const;
    00364
    00365       virtual result
    00366       do_in(state_type& __state, const extern_type* __from,
    00367         const extern_type* __from_end, const extern_type*& __from_next,
    00368         intern_type* __to, intern_type* __to_end,
    00369         intern_type*& __to_next) const;
    00370
    00371       virtual int
    00372       do_encoding() const throw();
    00373
    00374       virtual bool
    00375       do_always_noconv() const throw();
    00376
    00377       virtual int
    00378       do_length(state_type&, const extern_type* __from,
    00379         const extern_type* __end, size_t __max) const;
    00380
    00381       virtual int
    00382       do_max_length() const throw();
    00383   };
    00384
    00385 #ifdef _GLIBCXX_USE_WCHAR_T
    00386   /// class codecvt<wchar_t, char, mbstate_t> specialization.
    00387   template<>
    00388     class codecvt<wchar_t, char, mbstate_t>
    00389     : public __codecvt_abstract_base<wchar_t, char, mbstate_t>
    00390     {
    00391     public:
    00392       // Types:
    00393       typedef wchar_t           intern_type;
    00394       typedef char          extern_type;
    00395       typedef mbstate_t         state_type;
    00396
    00397     protected:
    00398       __c_locale            _M_c_locale_codecvt;
    00399
    00400     public:
    00401       static locale::id         id;
    00402
    00403       explicit
    00404       codecvt(size_t __refs = 0);
    00405
    00406       explicit
    00407       codecvt(__c_locale __cloc, size_t __refs = 0);
    00408
    00409     protected:
    00410       virtual
    00411       ~codecvt();
    00412
    00413       virtual result
    00414       do_out(state_type& __state, const intern_type* __from,
    00415          const intern_type* __from_end, const intern_type*& __from_next,
    00416          extern_type* __to, extern_type* __to_end,
    00417          extern_type*& __to_next) const;
    00418
    00419       virtual result
    00420       do_unshift(state_type& __state,
    00421          extern_type* __to, extern_type* __to_end,
    00422          extern_type*& __to_next) const;
    00423
    00424       virtual result
    00425       do_in(state_type& __state,
    00426          const extern_type* __from, const extern_type* __from_end,
    00427          const extern_type*& __from_next,
    00428          intern_type* __to, intern_type* __to_end,
    00429          intern_type*& __to_next) const;
    00430
    00431       virtual
    00432       int do_encoding() const throw();
    00433
    00434       virtual
    00435       bool do_always_noconv() const throw();
    00436
    00437       virtual
    00438       int do_length(state_type&, const extern_type* __from,
    00439             const extern_type* __end, size_t __max) const;
    00440
    00441       virtual int
    00442       do_max_length() const throw();
    00443     };
    00444 #endif //_GLIBCXX_USE_WCHAR_T
    00445
    00446   /// class codecvt_byname [22.2.1.6].
    00447   template<typename _InternT, typename _ExternT, typename _StateT>
    00448     class codecvt_byname : public codecvt<_InternT, _ExternT, _StateT>
    00449     {
    00450     public:
    00451       explicit
    00452       codecvt_byname(const char* __s, size_t __refs = 0)
    00453       : codecvt<_InternT, _ExternT, _StateT>(__refs)
    00454       {
    00455     if (__builtin_strcmp(__s, "C") != 0
    00456         && __builtin_strcmp(__s, "POSIX") != 0)
    00457       {
    00458         this->_S_destroy_c_locale(this->_M_c_locale_codecvt);
    00459         this->_S_create_c_locale(this->_M_c_locale_codecvt, __s);
    00460       }
    00461       }
    00462
    00463     protected:
    00464       virtual
    00465       ~codecvt_byname() { }
    00466     };
    00467
    00468   // Inhibit implicit instantiations for required instantiations,
    00469   // which are defined via explicit instantiations elsewhere.
    00470   // NB: This syntax is a GNU extension.
    00471 #if _GLIBCXX_EXTERN_TEMPLATE
    00472   extern template class codecvt_byname<char, char, mbstate_t>;
    00473
    00474   extern template
    00475     const codecvt<char, char, mbstate_t>&
    00476     use_facet<codecvt<char, char, mbstate_t> >(const locale&);
    00477
    00478   extern template
    00479     bool
    00480     has_facet<codecvt<char, char, mbstate_t> >(const locale&);
    00481
    00482 #ifdef _GLIBCXX_USE_WCHAR_T
    00483   extern template class codecvt_byname<wchar_t, char, mbstate_t>;
    00484
    00485   extern template
    00486     const codecvt<wchar_t, char, mbstate_t>&
    00487     use_facet<codecvt<wchar_t, char, mbstate_t> >(const locale&);
    00488
    00489   extern template
    00490     bool
    00491     has_facet<codecvt<wchar_t, char, mbstate_t> >(const locale&);
    00492 #endif
    00493 #endif
    00494
    00495 _GLIBCXX_END_NAMESPACE
    00496
    00497 #endif // _CODECVT_H