codecvt.h

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// Locale support (codecvt) -*- C++ -*-

// Copyright (C) 2000, 2001 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

//
// ISO C++ 14882: 22.2.1.5 Template class codecvt
//

// Warning: this file is not meant for user inclusion.  Use <locale>.

// Written by Benjamin Kosnik <[e-mail]>

#ifndef _CPP_BITS_CODECVT_H
#define _CPP_BITS_CODECVT_H	1

#pragma GCC system_header

  // XXX 
  // __enc_traits may need to move up the locale header hierarchy,
  // depending on if ctype ends up using it.

#ifdef _GLIBCPP_USE_WCHAR_T
  // Extensions to use icov for dealing with character encodings,
  // including conversions and comparisons between various character
  // sets.  This object encapsulates data that may need to be shared between
  // char_traits, codecvt and ctype.

#if _GLIBCPP_USE_SHADOW_HEADERS
  using _C_legacy::CODESET;
#endif

  class __enc_traits
  {
  public:
    // Types: 
    // NB: A conversion descriptor subsumes and enhances the
    // functionality of a simple state type such as mbstate_t.
    typedef iconv_t	__desc_type;
    
  protected:
    // Data Members:
    // Max size of charset encoding name
    static const int 	_S_max_size = 32;
    // Name of internal character set encoding.
    char	       	_M_int_enc[_S_max_size];
    // Name of external character set encoding.
    char  	       	_M_ext_enc[_S_max_size];

    // Conversion descriptor between external encoding to internal encoding.
    __desc_type		_M_in_desc;
    // Conversion descriptor between internal encoding to external encoding.
    __desc_type		_M_out_desc;

    // Details the byte-order marker for the external encoding, if necessary.
    int			_M_ext_bom;

    // Details the byte-order marker for the internal encoding, if necessary.
    int			_M_int_bom;

  public:
    __enc_traits()
    : _M_in_desc(0), _M_out_desc(0), _M_ext_bom(0), _M_int_bom(0)
    {
      // __intc_end = whatever we are using internally, which is
      // UCS4 (linux) 
      // UCS2 == UNICODE  (microsoft, java, aix, whatever...)
      // XXX Currently don't know how to get this data from target system...
      strcpy(_M_int_enc, "UCS4");

      // __extc_end = external codeset in current locale
      strcpy(_M_ext_enc, nl_langinfo(CODESET));
    }

    __enc_traits(const char* __int, const char* __ext, int __ibom = 0, 
		 int __ebom = 0)
    : _M_in_desc(0), _M_out_desc(0), _M_ext_bom(0), _M_int_bom(0)
    {
      strncpy(_M_int_enc, __int, _S_max_size);
      strncpy(_M_ext_enc, __ext, _S_max_size);
    }

    // 21.1.2 traits typedefs
    // p4
    // typedef STATE_T state_type
    // requires: state_type shall meet the requirements of
    // CopyConstructible types (20.1.3)
    __enc_traits(const __enc_traits& __obj)
    {
      strncpy(_M_int_enc, __obj._M_int_enc, _S_max_size);
      strncpy(_M_ext_enc, __obj._M_ext_enc, _S_max_size);
      _M_ext_bom = __obj._M_ext_bom;
      _M_int_bom = __obj._M_int_bom;
    }

    ~__enc_traits()
    {
      iconv_close(_M_in_desc);
      iconv_close(_M_out_desc);
    } 

    // Initializes
    void
    _M_init()
    {
      _M_in_desc = iconv_open(_M_int_enc, _M_ext_enc);
      _M_out_desc = iconv_open(_M_ext_enc, _M_int_enc);
      if (_M_out_desc == iconv_t(-1) || _M_in_desc == iconv_t(-1))
	{
	  // XXX Extended error checking.
	}
    }

    bool
    _M_good()
    { 
      return _M_out_desc && _M_in_desc 
	     && _M_out_desc != iconv_t(-1) && _M_in_desc != iconv_t(-1);
    }

    const __desc_type* 
    _M_get_in_descriptor()
    { return &_M_in_desc; }

    const __desc_type* 
    _M_get_out_descriptor()
    { return &_M_out_desc; }

   const char* 
    _M_get_internal_enc()
    { return _M_int_enc; }

    const char* 
    _M_get_external_enc()
    { return _M_ext_enc; }

    int 
    _M_get_external_bom()
    { return _M_ext_bom; }

    int 
    _M_get_internal_bom()
    { return _M_int_bom; }
  };
#endif //_GLIBCPP_USE_WCHAR_T


  //  22.2.1.5  Template class codecvt
  class codecvt_base
  {
  public:
    enum result
    {
      ok,
      partial,
      error,
      noconv
    };
  };

  // Template class __codecvt_abstract_base
  // NB: An abstract base class that fills in the public inlines, so
  // that the specializations don't have to re-copy the public
  // interface.
  template<typename _InternT, typename _ExternT, typename _StateT>
    class __codecvt_abstract_base 
    : public locale::facet, public codecvt_base
    {
    public:
      // Types:
      typedef codecvt_base::result			result;
      typedef _InternT 					intern_type;
      typedef _ExternT 					extern_type;
      typedef _StateT  					state_type;
      
      // 22.2.1.5.1 codecvt members
      result
      out(state_type& __state, const intern_type* __from, 
	  const intern_type* __from_end, const intern_type*& __from_next,
	  extern_type* __to, extern_type* __to_end, 
	  extern_type*& __to_next) const
      { 
	return this->do_out(__state, __from, __from_end, __from_next, 
			    __to, __to_end, __to_next); 
      }

      result
      unshift(state_type& __state, extern_type* __to, extern_type* __to_end,
	      extern_type*& __to_next) const
      { return this->do_unshift(__state, __to,__to_end,__to_next); }

      result
      in(state_type& __state, const extern_type* __from, 
	 const extern_type* __from_end, const extern_type*& __from_next,
	 intern_type* __to, intern_type* __to_end, 
	 intern_type*& __to_next) const
      { 
	return this->do_in(__state, __from, __from_end, __from_next,
			   __to, __to_end, __to_next); 
      }

      int 
      encoding() const throw()
      { return this->do_encoding(); }

      bool 
      always_noconv() const throw()
      { return this->do_always_noconv(); }

      int
      length(const state_type& __state, const extern_type* __from,
	     const extern_type* __end, size_t __max) const
      { return this->do_length(__state, __from, __end, __max); }

      int 
      max_length() const throw()
      { return this->do_max_length(); }

    protected:
      explicit 
      __codecvt_abstract_base(size_t __refs = 0) : locale::facet(__refs) { }

      virtual 
      ~__codecvt_abstract_base() { }

      virtual result
      do_out(state_type& __state, const intern_type* __from, 
	     const intern_type* __from_end, const intern_type*& __from_next,
	     extern_type* __to, extern_type* __to_end,
	     extern_type*& __to_next) const = 0;

      virtual result
      do_unshift(state_type& __state, extern_type* __to, 
		 extern_type* __to_end, extern_type*& __to_next) const = 0;
      
      virtual result
      do_in(state_type& __state, const extern_type* __from, 
	    const extern_type* __from_end, const extern_type*& __from_next, 
	    intern_type* __to, intern_type* __to_end, 
	    intern_type*& __to_next) const = 0;
      
      virtual int 
      do_encoding() const throw() = 0;

      virtual bool 
      do_always_noconv() const throw() = 0;

      virtual int 
      do_length(const state_type&, const extern_type* __from, 
		const extern_type* __end, size_t __max) const = 0;

      virtual int 
      do_max_length() const throw() = 0;
    };

  // 22.2.1.5 Template class codecvt
  // NB: Generic, mostly useless implementation.
  template<typename _InternT, typename _ExternT, typename _StateT>
    class codecvt 
    : public __codecvt_abstract_base<_InternT, _ExternT, _StateT>
    {
    public:      
      // Types:
      typedef codecvt_base::result			result;
      typedef _InternT intern_type;
      typedef _ExternT extern_type;
      typedef _StateT  state_type;

      // Data Members:
      static locale::id id;

      explicit 
      codecvt(size_t __refs = 0) 
      : __codecvt_abstract_base<_InternT,_ExternT,_StateT> (__refs) { }

    protected:
      virtual 
      ~codecvt() { }
    };

  template<typename _InternT, typename _ExternT, typename _StateT>
    locale::id codecvt<_InternT, _ExternT, _StateT>::id;

#ifdef _GLIBCPP_USE_WCHAR_T
  // partial specialization
  // This specialization takes advantage of iconv to provide code
  // conversions between a large number of character encodings.
  template<typename _InternT, typename _ExternT>
    class codecvt<_InternT, _ExternT, __enc_traits>
    : public __codecvt_abstract_base<_InternT, _ExternT, __enc_traits>
    {
    public:      
      // Types:
      typedef codecvt_base::result			result;
      typedef _InternT 					intern_type;
      typedef _ExternT 					extern_type;
      typedef __enc_traits 				state_type;
      typedef __enc_traits::__desc_type 		__desc_type;
      typedef __enc_traits				__enc_type;

      // Data Members:
      static locale::id 		id;

      explicit 
      codecvt(size_t __refs = 0)
      : __codecvt_abstract_base<intern_type, extern_type, state_type>(__refs)
      { }

      explicit 
      codecvt(__enc_type* __enc, size_t __refs = 0)
      : __codecvt_abstract_base<intern_type, extern_type, state_type>(__refs)
      { }

    protected:
      virtual 
      ~codecvt() { }

      virtual result
      do_out(state_type& __state, const intern_type* __from, 
	     const intern_type* __from_end, const intern_type*& __from_next,
	     extern_type* __to, extern_type* __to_end,
	     extern_type*& __to_next) const;

      virtual result
      do_unshift(state_type& __state, extern_type* __to, 
		 extern_type* __to_end, extern_type*& __to_next) const;

      virtual result
      do_in(state_type& __state, const extern_type* __from, 
	    const extern_type* __from_end, const extern_type*& __from_next,
	    intern_type* __to, intern_type* __to_end, 
	    intern_type*& __to_next) const;

      virtual int 
      do_encoding() const throw();