a60-svg-codecvt.h

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// alpha60 codecvt utf8 -*- mode: C++ -*-
 
// alpha60
// bittorrent x scrape x data + analytics
 
// Copyright (c) 2016-2024, Benjamin De Kosnik <b.dekosnik@gmail.com>
 
// This file is part of the alpha60 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 3, 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.
 
#ifndef a60_SVG_CODECVT_H
#define a60_SVG_CODECVT_H 1
 
#include <ext/codecvt_specializations.h>
 
 
namespace svg {
 
/// Convert from ISO-8859-1 encoding to UTF-8, required for XML.
string
convert_8859_to_utf8(string in)
{
  using namespace std;
 
  using result = codecvt_base::result;
  using int_type = char;
  using ext_type = char;
  using state_type = __gnu_cxx::encoding_state;
  using ccutf8_codecvt = codecvt<int_type, ext_type, state_type>;
 
  string out;
  const int_type* internal_ptr;
  ext_type* external_ptr;
  ext_type* buf = new int_type[in.size() * 3];
 
  // Use iconv on linux, ie `iconv --list`
 
  // Internal encoding is ISO 8859 and external is UTF-8.
  state_type state("ISO-8859-16", "UTF-8", 0, 0);
 
  ccutf8_codecvt* cvtf8 = new ccutf8_codecvt;
  locale loc(locale::classic(), cvtf8);
  const ccutf8_codecvt& cvt = use_facet<ccutf8_codecvt>(loc);
  result r = cvt.out(state, in.c_str(), in.c_str() + in.size(), internal_ptr,
             buf, buf + in.size() * 3, external_ptr);
  if (r == codecvt_base::ok)
    out = string(buf, external_ptr);
  else
    {
      if (r == codecvt_base::partial)
    {
      ext_type* n_ptr = external_ptr;
      while (n_ptr > external_ptr)
        {
          external_ptr = n_ptr;
          r = cvt.in(state, in.c_str(), in.c_str() + in.size(),
             internal_ptr, buf, buf + in.size() * 3, n_ptr);
        }
 
      if (r == codecvt_base::ok)
        out = string(buf, n_ptr);
      else
        {
          std::cerr << "convert_to_utf8: partial at "
            << ulong(n_ptr - in.c_str()) << " "
            << in << std::endl;
          out = in;
        }
    }
      if (r == codecvt_base::error)
    {
      std::cerr << "convert_to_utf8: error " << in << std::endl;
      out = in;
    }
    }
 
  // Any escape characters may have to be wrapped for HTML with &#[0][0][0];
  //delete cvtf8;
  delete [] buf;
 
  return out;
}
 
 
string
convert_to_utf8(string in)
{ return convert_8859_to_utf8(in); }
 
} // namespace svg
#endif