// UniUtil.cpp

//

// Example code for handling UTF-8 encoding

//

// Otfried Cheong



#include <e32std.h>



class Uni {

public:

  // convert UTF8 to Unicode (forward and backward)

  enum { KIllegal = 0xffff, KIncomplete = 0xf800, KHeadless = 0xf801 };

  static TText16 WChar(const TDesC8 &aDes, TInt &aPos);

  static TText16 Previous(const TDesC8 &aDes, TInt &aPos);



  // convert Unicode to UTF8

  static TBuf8<3> UTF8(TText16 wc);

  static void AppendUTF8(TDes8 &aUtf, TText16 aWChar);



  // Count characters in string

  static TInt Count(const TDesC8 &aDes);

  // Find Length of prefix in bytes for given # of chars

  static TInt Bytes(const TDesC8 &aDes, TInt aNoChars);

};



//-----------------------------------------------------------------



GLDEF_C const TUint8 bytesFromUTF8[256] = {

  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,

  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 3,3,3,3,3,3,3,3,4,4,4,4,5,5,5,5};



LOCAL_C const TText16 firstByteMark[7] = {

  0x00, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC, 0 };



// convert UTF8 to Unicode

// special cases:  end of string in UTF8 sequence --> KIncomplete

//                 UTF8 sequence stops prematurely --> KIllegal

//                 UTF8 sequence starts with trailer --> KHeadless

TText16 Uni::WChar(const TDesC8 &aDes, TInt &aPos)

{

  TUint wch = aDes[aPos++];

  if ((wch & 0xc0) == 0x80) {

    // KHeadless

    while (aPos < aDes.Length() && (aDes[aPos] & 0xc0) == 0x80)

      aPos++;

    return KHeadless;

  }

  TInt extraBytes = bytesFromUTF8[wch & 0xff];

  wch -= firstByteMark[extraBytes];

  while (extraBytes--) {

    if (aPos >= aDes.Length())

      return TText16(KIncomplete);

    if ((aDes[aPos] & 0xc0) != 0x80)

      // return TText16(aDes[aPos - 1]);

      return TText16(KIllegal);

    wch <<= 6;

    wch |= aDes[aPos++] & 0x3f; 

  }

  return TText16(wch);

}



// same backwards

TText16 Uni::Previous(const TDesC8 &aDes, TInt &aPos)

{

  TInt i = aPos - 1;

  while (i >= 0 && aDes[i] >= 0x80 && aDes[i] < 0xc0)

    i--;

  aPos = i;

  return WChar(aDes, i);

}



// convert Unicode to UTF8

TBuf8<3> Uni::UTF8(TText16 wch)

{

  TBuf8<3> aBuf;

  AppendUTF8(aBuf, wch);

  return aBuf;

}



// convert Unicode to UTF8

void Uni::AppendUTF8(TDes8 &aUtf, TText16 wch)

{

  if (wch < 0x80) {

    aUtf.Append(TChar(wch));

  } else if (wch < 0x800) {

    aUtf.Append(TChar(((wch & 0x7c0) >> 6) | 0xc0));

    aUtf.Append(TChar((wch & 0x03f) | 0x80));

  } else {

    // We never need to write UCS larger than 0x10000,

    // so now it's three bytes 

    aUtf.Append(TChar(((wch & 0x0f000) >> 12) | 0xe0));

    aUtf.Append(TChar(((wch & 0xfc0) >> 6) | 0x80));

    aUtf.Append(TChar((wch & 0x03f) | 0x80));

  }

}



// Count characters in string

TInt Uni::Count(const TDesC8 &aDes)

{

  TInt i, k = 0;

  TUint ch;

  for (i = 0; i < aDes.Length(); i++) {

    ch = aDes[i];

    if (ch < 0x80 || ch >= 0xc0) 

      k++;

  }

  // last character might not be complete

  return k;

}



// Find Length of prefix in bytes for given # chars

TInt Uni::Bytes(const TDesC8 &aDes, TInt aNoChars)

{

  TInt i = 0;

  while (aNoChars && i < aDes.Length()) {

    WChar(aDes, i);

    aNoChars--;

  }

  return i;

}



// --------------------------------------------------------------------