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

   1 // Locale support (codecvt) -*- C++ -*-
   2
   3 // Copyright (C) 2000-2014 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 /** @file bits/codecvt.h
  26  *  This is an internal header file, included by other library headers.
  27  *  Do not attempt to use it directly. @headername{locale}
  28  */
  29
  30 //
  31 // ISO C++ 14882: 22.2.1.5 Template class codecvt
  32 //
  33
  34 // Written by Benjamin Kosnik <bkoz@redhat.com>
  35
  36 #ifndef _CODECVT_H
  37 #define _CODECVT_H 1
  38
  39 #pragma GCC system_header
  40
  41 namespace std _GLIBCXX_VISIBILITY(default)
  42 {
  43 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  44
  45   /// Empty base class for codecvt facet [22.2.1.5].
  46   class codecvt_base
  47   {
  48   public:
  49     enum result
  50     {
  51       ok,
  52       partial,
  53       error,
  54       noconv
  55     };
  56   };
  57
  58   /**
  59    *  @brief  Common base for codecvt functions.
  60    *
  61    *  This template class provides implementations of the public functions
  62    *  that forward to the protected virtual functions.
  63    *
  64    *  This template also provides abstract stubs for the protected virtual
  65    *  functions.
  66   */
  67   template<typename _InternT, typename _ExternT, typename _StateT>
  68     class __codecvt_abstract_base
  69     : public locale::facet, public codecvt_base
  70     {
  71     public:
  72       // Types:
  73       typedef codecvt_base::result      result;
  74       typedef _InternT                  intern_type;
  75       typedef _ExternT                  extern_type;
  76       typedef _StateT                   state_type;
  77
  78       // 22.2.1.5.1 codecvt members
  79       /**
  80        *  @brief  Convert from internal to external character set.
  81        *
  82        *  Converts input string of intern_type to output string of
  83        *  extern_type.  This is analogous to wcsrtombs.  It does this by
  84        *  calling codecvt::do_out.
  85        *
  86        *  The source and destination character sets are determined by the
  87        *  facet's locale, internal and external types.
  88        *
  89        *  The characters in [from,from_end) are converted and written to
  90        *  [to,to_end).  from_next and to_next are set to point to the
  91        *  character following the last successfully converted character,
  92        *  respectively.  If the result needed no conversion, from_next and
  93        *  to_next are not affected.
  94        *
  95        *  The @a state argument should be initialized if the input is at the
  96        *  beginning and carried from a previous call if continuing
  97        *  conversion.  There are no guarantees about how @a state is used.
  98        *
  99        *  The result returned is a member of codecvt_base::result.  If
 100        *  all the input is converted, returns codecvt_base::ok.  If no
 101        *  conversion is necessary, returns codecvt_base::noconv.  If
 102        *  the input ends early or there is insufficient space in the
 103        *  output, returns codecvt_base::partial.  Otherwise the
 104        *  conversion failed and codecvt_base::error is returned.
 105        *
 106        *  @param  __state  Persistent conversion state data.
 107        *  @param  __from  Start of input.
 108        *  @param  __from_end  End of input.
 109        *  @param  __from_next  Returns start of unconverted data.
 110        *  @param  __to  Start of output buffer.
 111        *  @param  __to_end  End of output buffer.
 112        *  @param  __to_next  Returns start of unused output area.
 113        *  @return  codecvt_base::result.
 114       */
 115       result
 116       out(state_type& __state, const intern_type* __from,
 117           const intern_type* __from_end, const intern_type*& __from_next,
 118           extern_type* __to, extern_type* __to_end,
 119           extern_type*& __to_next) const
 120       {
 121         return this->do_out(__state, __from, __from_end, __from_next,
 122                             __to, __to_end, __to_next);
 123       }
 124
 125       /**
 126        *  @brief  Reset conversion state.
 127        *
 128        *  Writes characters to output that would restore @a state to initial
 129        *  conditions.  The idea is that if a partial conversion occurs, then
 130        *  the converting the characters written by this function would leave
 131        *  the state in initial conditions, rather than partial conversion
 132        *  state.  It does this by calling codecvt::do_unshift().
 133        *
 134        *  For example, if 4 external characters always converted to 1 internal
 135        *  character, and input to in() had 6 external characters with state
 136        *  saved, this function would write two characters to the output and
 137        *  set the state to initialized conditions.
 138        *
 139        *  The source and destination character sets are determined by the
 140        *  facet's locale, internal and external types.
 141        *
 142        *  The result returned is a member of codecvt_base::result.  If the
 143        *  state could be reset and data written, returns codecvt_base::ok.  If
 144        *  no conversion is necessary, returns codecvt_base::noconv.  If the
 145        *  output has insufficient space, returns codecvt_base::partial.
 146        *  Otherwise the reset failed and codecvt_base::error is returned.
 147        *
 148        *  @param  __state  Persistent conversion state data.
 149        *  @param  __to  Start of output buffer.
 150        *  @param  __to_end  End of output buffer.
 151        *  @param  __to_next  Returns start of unused output area.
 152        *  @return  codecvt_base::result.
 153       */
 154       result
 155       unshift(state_type& __state, extern_type* __to, extern_type* __to_end,
 156               extern_type*& __to_next) const
 157       { return this->do_unshift(__state, __to,__to_end,__to_next); }
 158
 159       /**
 160        *  @brief  Convert from external to internal character set.
 161        *
 162        *  Converts input string of extern_type to output string of
 163        *  intern_type.  This is analogous to mbsrtowcs.  It does this by
 164        *  calling codecvt::do_in.
 165        *
 166        *  The source and destination character sets are determined by the
 167        *  facet's locale, internal and external types.
 168        *
 169        *  The characters in [from,from_end) are converted and written to
 170        *  [to,to_end).  from_next and to_next are set to point to the
 171        *  character following the last successfully converted character,
 172        *  respectively.  If the result needed no conversion, from_next and
 173        *  to_next are not affected.
 174        *
 175        *  The @a state argument should be initialized if the input is at the
 176        *  beginning and carried from a previous call if continuing
 177        *  conversion.  There are no guarantees about how @a state is used.
 178        *
 179        *  The result returned is a member of codecvt_base::result.  If
 180        *  all the input is converted, returns codecvt_base::ok.  If no
 181        *  conversion is necessary, returns codecvt_base::noconv.  If
 182        *  the input ends early or there is insufficient space in the
 183        *  output, returns codecvt_base::partial.  Otherwise the
 184        *  conversion failed and codecvt_base::error is returned.
 185        *
 186        *  @param  __state  Persistent conversion state data.
 187        *  @param  __from  Start of input.
 188        *  @param  __from_end  End of input.
 189        *  @param  __from_next  Returns start of unconverted data.
 190        *  @param  __to  Start of output buffer.
 191        *  @param  __to_end  End of output buffer.
 192        *  @param  __to_next  Returns start of unused output area.
 193        *  @return  codecvt_base::result.
 194       */
 195       result
 196       in(state_type& __state, const extern_type* __from,
 197          const extern_type* __from_end, const extern_type*& __from_next,
 198          intern_type* __to, intern_type* __to_end,
 199          intern_type*& __to_next) const
 200       {
 201         return this->do_in(__state, __from, __from_end, __from_next,
 202                            __to, __to_end, __to_next);
 203       }
 204
 205       int
 206       encoding() const throw()
 207       { return this->do_encoding(); }
 208
 209       bool
 210       always_noconv() const throw()
 211       { return this->do_always_noconv(); }
 212
 213       int
 214       length(state_type& __state, const extern_type* __from,
 215              const extern_type* __end, size_t __max) const
 216       { return this->do_length(__state, __from, __end, __max); }
 217
 218       int
 219       max_length() const throw()
 220       { return this->do_max_length(); }
 221
 222     protected:
 223       explicit
 224       __codecvt_abstract_base(size_t __refs = 0) : locale::facet(__refs) { }
 225
 226       virtual
 227       ~__codecvt_abstract_base() { }
 228
 229       /**
 230        *  @brief  Convert from internal to external character set.
 231        *
 232        *  Converts input string of intern_type to output string of
 233        *  extern_type.  This function is a hook for derived classes to change
 234        *  the value returned.  @see out for more information.
 235       */
 236       virtual result
 237       do_out(state_type& __state, const intern_type* __from,
 238              const intern_type* __from_end, const intern_type*& __from_next,
 239              extern_type* __to, extern_type* __to_end,
 240              extern_type*& __to_next) const = 0;
 241
 242       virtual result
 243       do_unshift(state_type& __state, extern_type* __to,
 244                  extern_type* __to_end, extern_type*& __to_next) const = 0;
 245
 246       virtual result
 247       do_in(state_type& __state, const extern_type* __from,
 248             const extern_type* __from_end, const extern_type*& __from_next,
 249             intern_type* __to, intern_type* __to_end,
 250             intern_type*& __to_next) const = 0;
 251
 252       virtual int
 253       do_encoding() const throw() = 0;
 254
 255       virtual bool
 256       do_always_noconv() const throw() = 0;
 257
 258       virtual int
 259       do_length(state_type&, const extern_type* __from,
 260                 const extern_type* __end, size_t __max) const = 0;
 261
 262       virtual int
 263       do_max_length() const throw() = 0;
 264     };
 265
 266
 267
 268   /**
 269    *  @brief  Primary class template codecvt.
 270    *  @ingroup locales
 271    *
 272    *  NB: Generic, mostly useless implementation.
 273    *
 274   */
 275    template<typename _InternT, typename _ExternT, typename _StateT>
 276     class codecvt
 277     : public __codecvt_abstract_base<_InternT, _ExternT, _StateT>
 278     {
 279     public:
 280       // Types:
 281       typedef codecvt_base::result      result;
 282       typedef _InternT                  intern_type;
 283       typedef _ExternT                  extern_type;
 284       typedef _StateT                   state_type;
 285
 286     protected:
 287       __c_locale                        _M_c_locale_codecvt;
 288
 289     public:
 290       static locale::id                 id;
 291
 292       explicit
 293       codecvt(size_t __refs = 0)
 294       : __codecvt_abstract_base<_InternT, _ExternT, _StateT> (__refs),
 295         _M_c_locale_codecvt(0)
 296       { }
 297
 298       explicit
 299       codecvt(__c_locale __cloc, size_t __refs = 0);
 300
 301     protected:
 302       virtual
 303       ~codecvt() { }
 304
 305       virtual result
 306       do_out(state_type& __state, const intern_type* __from,
 307              const intern_type* __from_end, const intern_type*& __from_next,
 308              extern_type* __to, extern_type* __to_end,
 309              extern_type*& __to_next) const;
 310
 311       virtual result
 312       do_unshift(state_type& __state, extern_type* __to,
 313                  extern_type* __to_end, extern_type*& __to_next) const;
 314
 315       virtual result
 316       do_in(state_type& __state, const extern_type* __from,
 317             const extern_type* __from_end, const extern_type*& __from_next,
 318             intern_type* __to, intern_type* __to_end,
 319             intern_type*& __to_next) const;
 320
 321       virtual int
 322       do_encoding() const throw();
 323
 324       virtual bool
 325       do_always_noconv() const throw();
 326
 327       virtual int
 328       do_length(state_type&, const extern_type* __from,
 329                 const extern_type* __end, size_t __max) const;
 330
 331       virtual int
 332       do_max_length() const throw();
 333     };
 334
 335   template<typename _InternT, typename _ExternT, typename _StateT>
 336     locale::id codecvt<_InternT, _ExternT, _StateT>::id;
 337
 338   /// class codecvt<char, char, mbstate_t> specialization.
 339   template<>
 340     class codecvt<char, char, mbstate_t>
 341     : public __codecvt_abstract_base<char, char, mbstate_t>
 342     {
 343     public:
 344       // Types:
 345       typedef char                      intern_type;
 346       typedef char                      extern_type;
 347       typedef mbstate_t                 state_type;
 348
 349     protected:
 350       __c_locale                        _M_c_locale_codecvt;
 351
 352     public:
 353       static locale::id id;
 354
 355       explicit
 356       codecvt(size_t __refs = 0);
 357
 358       explicit
 359       codecvt(__c_locale __cloc, size_t __refs = 0);
 360
 361     protected:
 362       virtual
 363       ~codecvt();
 364
 365       virtual result
 366       do_out(state_type& __state, const intern_type* __from,
 367              const intern_type* __from_end, const intern_type*& __from_next,
 368              extern_type* __to, extern_type* __to_end,
 369              extern_type*& __to_next) const;
 370
 371       virtual result
 372       do_unshift(state_type& __state, extern_type* __to,
 373                  extern_type* __to_end, extern_type*& __to_next) const;
 374
 375       virtual result
 376       do_in(state_type& __state, const extern_type* __from,
 377             const extern_type* __from_end, const extern_type*& __from_next,
 378             intern_type* __to, intern_type* __to_end,
 379             intern_type*& __to_next) const;
 380
 381       virtual int
 382       do_encoding() const throw();
 383
 384       virtual bool
 385       do_always_noconv() const throw();
 386
 387       virtual int
 388       do_length(state_type&, const extern_type* __from,
 389                 const extern_type* __end, size_t __max) const;
 390
 391       virtual int
 392       do_max_length() const throw();
 393   };
 394
 395 #ifdef _GLIBCXX_USE_WCHAR_T
 396   /// class codecvt<wchar_t, char, mbstate_t> specialization.
 397   template<>
 398     class codecvt<wchar_t, char, mbstate_t>
 399     : public __codecvt_abstract_base<wchar_t, char, mbstate_t>
 400     {
 401     public:
 402       // Types:
 403       typedef wchar_t                   intern_type;
 404       typedef char                      extern_type;
 405       typedef mbstate_t                 state_type;
 406
 407     protected:
 408       __c_locale                        _M_c_locale_codecvt;
 409
 410     public:
 411       static locale::id                 id;
 412
 413       explicit
 414       codecvt(size_t __refs = 0);
 415
 416       explicit
 417       codecvt(__c_locale __cloc, size_t __refs = 0);
 418
 419     protected:
 420       virtual
 421       ~codecvt();
 422
 423       virtual result
 424       do_out(state_type& __state, const intern_type* __from,
 425              const intern_type* __from_end, const intern_type*& __from_next,
 426              extern_type* __to, extern_type* __to_end,
 427              extern_type*& __to_next) const;
 428
 429       virtual result
 430       do_unshift(state_type& __state,
 431                  extern_type* __to, extern_type* __to_end,
 432                  extern_type*& __to_next) const;
 433
 434       virtual result
 435       do_in(state_type& __state,
 436              const extern_type* __from, const extern_type* __from_end,
 437              const extern_type*& __from_next,
 438              intern_type* __to, intern_type* __to_end,
 439              intern_type*& __to_next) const;
 440
 441       virtual
 442       int do_encoding() const throw();
 443
 444       virtual
 445       bool do_always_noconv() const throw();
 446
 447       virtual
 448       int do_length(state_type&, const extern_type* __from,
 449                     const extern_type* __end, size_t __max) const;
 450
 451       virtual int
 452       do_max_length() const throw();
 453     };
 454 #endif //_GLIBCXX_USE_WCHAR_T
 455
 456   /// class codecvt_byname [22.2.1.6].
 457   template<typename _InternT, typename _ExternT, typename _StateT>
 458     class codecvt_byname : public codecvt<_InternT, _ExternT, _StateT>
 459     {
 460     public:
 461       explicit
 462       codecvt_byname(const char* __s, size_t __refs = 0)
 463       : codecvt<_InternT, _ExternT, _StateT>(__refs)
 464       {
 465         if (__builtin_strcmp(__s, "C") != 0
 466             && __builtin_strcmp(__s, "POSIX") != 0)
 467           {
 468             this->_S_destroy_c_locale(this->_M_c_locale_codecvt);
 469             this->_S_create_c_locale(this->_M_c_locale_codecvt, __s);
 470           }
 471       }
 472
 473     protected:
 474       virtual
 475       ~codecvt_byname() { }
 476     };
 477
 478   // Inhibit implicit instantiations for required instantiations,
 479   // which are defined via explicit instantiations elsewhere.
 480 #if _GLIBCXX_EXTERN_TEMPLATE
 481   extern template class codecvt_byname<char, char, mbstate_t>;
 482
 483   extern template
 484     const codecvt<char, char, mbstate_t>&
 485     use_facet<codecvt<char, char, mbstate_t> >(const locale&);
 486
 487   extern template
 488     bool
 489     has_facet<codecvt<char, char, mbstate_t> >(const locale&);
 490
 491 #ifdef _GLIBCXX_USE_WCHAR_T
 492   extern template class codecvt_byname<wchar_t, char, mbstate_t>;
 493
 494   extern template
 495     const codecvt<wchar_t, char, mbstate_t>&
 496     use_facet<codecvt<wchar_t, char, mbstate_t> >(const locale&);
 497
 498   extern template
 499     bool
 500     has_facet<codecvt<wchar_t, char, mbstate_t> >(const locale&);
 501 #endif
 502 #endif
 503
 504 _GLIBCXX_END_NAMESPACE_VERSION
 505 } // namespace std
 506
 507 #endif // _CODECVT_H