src/common/convauto.cpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/common/convauto.cpp
   3 // Purpose:     implementation of wxConvAuto
   4 // Author:      Vadim Zeitlin
   5 // Created:     2006-04-04
   6 // RCS-ID:      $Id$
   7 // Copyright:   (c) 2006 Vadim Zeitlin <vadim@wxwindows.org>
   8 // Licence:     wxWindows licence
   9 ///////////////////////////////////////////////////////////////////////////////
  10
  11 // ============================================================================
  12 // declarations
  13 // ============================================================================
  14
  15 // ----------------------------------------------------------------------------
  16 // headers
  17 // ----------------------------------------------------------------------------
  18
  19 // for compilers that support precompilation, includes "wx.h".
  20 #include "wx/wxprec.h"
  21
  22 #ifdef __BORLANDC__
  23     #pragma hdrstop
  24 #endif
  25
  26 #if wxUSE_WCHAR_T
  27
  28 #ifndef WX_PRECOMP
  29 #endif //WX_PRECOMP
  30
  31 #include "wx/convauto.h"
  32
  33 // we use latin1 by default as it seems the least bad choice: the files we need
  34 // to detect input of don't always come from the user system (they are often
  35 // received from other machines) and so using wxFONTENCODING_SYSTEM doesn't
  36 // seem to be a good idea and there is no other reasonable alternative
  37 wxFontEncoding wxConvAuto::ms_defaultMBEncoding = wxFONTENCODING_ISO8859_1;
  38
  39 // ============================================================================
  40 // implementation
  41 // ============================================================================
  42
  43 /* static */
  44 void wxConvAuto::SetFallbackEncoding(wxFontEncoding enc)
  45 {
  46     wxASSERT_MSG( enc != wxFONTENCODING_DEFAULT,
  47                   _T("wxFONTENCODING_DEFAULT doesn't make sense here") );
  48
  49     ms_defaultMBEncoding = enc;
  50 }
  51
  52 /* static */
  53 wxConvAuto::BOMType wxConvAuto::DetectBOM(const char *src, size_t srcLen)
  54 {
  55     if ( srcLen < 2 )
  56     {
  57         // minimal BOM is 2 bytes so bail out immediately and simplify the code
  58         // below which wouldn't need to check for length for UTF-16 cases
  59         return BOM_None;
  60     }
  61
  62     // examine the buffer for BOM presence
  63     //
  64     // see http://www.unicode.org/faq/utf_bom.html#BOM
  65     switch ( *src++ )
  66     {
  67         case '\0':
  68             // could only be big endian UTF-32 (00 00 FE FF)
  69             if ( srcLen >= 4 &&
  70                     src[0] == '\0' &&
  71                         src[1] == '\xfe' &&
  72                             src[2] == '\xff' )
  73             {
  74                 return BOM_UTF32BE;
  75             }
  76             break;
  77
  78         case '\xfe':
  79             // could only be big endian UTF-16 (FE FF)
  80             if ( *src++ == '\xff' )
  81             {
  82                 return BOM_UTF16BE;
  83             }
  84             break;
  85
  86         case '\xff':
  87             // could be either little endian UTF-16 or UTF-32, both start
  88             // with FF FE
  89             if ( *src++ == '\xfe' )
  90             {
  91                 return srcLen >= 4 && src[0] == '\0' && src[1] == '\0'
  92                             ? BOM_UTF32LE
  93                             : BOM_UTF16LE;
  94             }
  95             break;
  96
  97         case '\xef':
  98             // is this UTF-8 BOM (EF BB BF)?
  99             if ( srcLen >= 3 && src[0] == '\xbb' && src[1] == '\xbf' )
 100             {
 101                 return BOM_UTF8;
 102             }
 103             break;
 104     }
 105
 106     return BOM_None;
 107 }
 108
 109 void wxConvAuto::InitFromBOM(BOMType bomType)
 110 {
 111     m_consumedBOM = false;
 112
 113     switch ( bomType )
 114     {
 115         case BOM_UTF32BE:
 116             m_conv = new wxMBConvUTF32BE;
 117             m_ownsConv = true;
 118             break;
 119
 120         case BOM_UTF32LE:
 121             m_conv = new wxMBConvUTF32LE;
 122             m_ownsConv = true;
 123             break;
 124
 125         case BOM_UTF16BE:
 126             m_conv = new wxMBConvUTF16BE;
 127             m_ownsConv = true;
 128             break;
 129
 130         case BOM_UTF16LE:
 131             m_conv = new wxMBConvUTF16LE;
 132             m_ownsConv = true;
 133             break;
 134
 135         case BOM_UTF8:
 136             InitWithUTF8();
 137             break;
 138
 139         default:
 140             wxFAIL_MSG( _T("unexpected BOM type") );
 141             // fall through: still need to create something
 142
 143         case BOM_None:
 144             InitWithUTF8();
 145             m_consumedBOM = true; // as there is nothing to consume
 146     }
 147 }
 148
 149 void wxConvAuto::SkipBOM(const char **src, size_t *len) const
 150 {
 151     int ofs;
 152     switch ( m_bomType )
 153     {
 154         case BOM_UTF32BE:
 155         case BOM_UTF32LE:
 156             ofs = 4;
 157             break;
 158
 159         case BOM_UTF16BE:
 160         case BOM_UTF16LE:
 161             ofs = 2;
 162             break;
 163
 164         case BOM_UTF8:
 165             ofs = 3;
 166             break;
 167
 168         default:
 169             wxFAIL_MSG( _T("unexpected BOM type") );
 170             // fall through: still need to create something
 171
 172         case BOM_None:
 173             ofs = 0;
 174     }
 175
 176     *src += ofs;
 177     if ( *len != (size_t)-1 )
 178         *len -= ofs;
 179 }
 180
 181 void wxConvAuto::InitFromInput(const char **src, size_t *len)
 182 {
 183     m_bomType = DetectBOM(*src, *len);
 184     InitFromBOM(m_bomType);
 185     SkipBOM(src, len);
 186 }
 187
 188 size_t
 189 wxConvAuto::ToWChar(wchar_t *dst, size_t dstLen,
 190                     const char *src, size_t srcLen) const
 191 {
 192     // we check BOM and create the appropriate conversion the first time we're
 193     // called but we also need to ensure that the BOM is skipped not only
 194     // during this initial call but also during the first call with non-NULL
 195     // dst as typically we're first called with NULL dst to calculate the
 196     // needed buffer size
 197     wxConvAuto *self = wx_const_cast(wxConvAuto *, this);
 198     if ( !m_conv )
 199     {
 200         self->InitFromInput(&src, &srcLen);
 201         if ( dst )
 202             self->m_consumedBOM = true;
 203     }
 204
 205     if ( !m_consumedBOM && dst )
 206     {
 207         self->m_consumedBOM = true;
 208         SkipBOM(&src, &srcLen);
 209     }
 210
 211     // try to convert using the auto-detected encoding
 212     size_t rc = m_conv->ToWChar(dst, dstLen, src, srcLen);
 213     if ( rc == wxCONV_FAILED && m_bomType == BOM_None )
 214     {
 215         // if the conversion failed but we didn't really detect anything and
 216         // simply tried UTF-8 by default, retry it using the fall-back
 217         if ( m_encDefault != wxFONTENCODING_MAX )
 218         {
 219             if ( m_ownsConv )
 220                 delete m_conv;
 221
 222             self->m_conv = new wxCSConv(m_encDefault == wxFONTENCODING_DEFAULT
 223                                             ? GetFallbackEncoding()
 224                                             : m_encDefault);
 225             self->m_ownsConv = true;
 226
 227             rc = m_conv->ToWChar(dst, dstLen, src, srcLen);
 228         }
 229     }
 230
 231     return rc;
 232 }
 233
 234 size_t
 235 wxConvAuto::FromWChar(char *dst, size_t dstLen,
 236                       const wchar_t *src, size_t srcLen) const
 237 {
 238     if ( !m_conv )
 239     {
 240         // default to UTF-8 for the multibyte output
 241         wx_const_cast(wxConvAuto *, this)->InitWithUTF8();
 242     }
 243
 244     return m_conv->FromWChar(dst, dstLen, src, srcLen);
 245 }
 246
 247 #endif // wxUSE_WCHAR_T
 248