public override bool IncrementToken()
 {
     while (true)
     {
         if (curTermBuffer == null)
         {
             if (!input.IncrementToken())
             {
                 return(false);
             }
             else
             {
                 curTermBuffer     = termAtt.Buffer().Clone();
                 curTermLength     = termAtt.Length();
                 curCodePointCount = charUtils.codePointCount(termAtt);
                 curGramSize       = minGram;
                 tokStart          = offsetAtt.StartOffset();
                 tokEnd            = offsetAtt.EndOffset();
                 if (version.OnOrAfter(Version.LUCENE_44))
                 {
                     // Never update offsets
                     updateOffsets = false;
                 }
                 else
                 {
                     // if length by start + end offsets doesn't match the term text then assume
                     // this is a synonym and don't adjust the offsets.
                     updateOffsets = (tokStart + curTermLength) == tokEnd;
                 }
                 savePosIncr += posIncrAtt.PositionIncrement;
                 savePosLen   = posLenAtt.PositionLength;
             }
         }
         if (curGramSize <= maxGram)               // if we have hit the end of our n-gram size range, quit
         {
             if (curGramSize <= curCodePointCount) // if the remaining input is too short, we can't generate any n-grams
             {
                 // grab gramSize chars from front or back
                 int start = side == Side.FRONT ? 0 : charUtils.offsetByCodePoints(curTermBuffer, 0, curTermLength, curTermLength, -curGramSize);
                 int end   = charUtils.offsetByCodePoints(curTermBuffer, 0, curTermLength, start, curGramSize);
                 ClearAttributes();
                 if (updateOffsets)
                 {
                     offsetAtt.SetOffset(tokStart + start, tokStart + end);
                 }
                 else
                 {
                     offsetAtt.SetOffset(tokStart, tokEnd);
                 }
                 // first ngram gets increment, others don't
                 if (curGramSize == minGram)
                 {
                     posIncrAtt.PositionIncrement = savePosIncr;
                     savePosIncr = 0;
                 }
                 else
                 {
                     posIncrAtt.PositionIncrement = 0;
                 }
                 posLenAtt.PositionLength = savePosLen;
                 termAtt.CopyBuffer(curTermBuffer, start, end - start);
                 curGramSize++;
                 return(true);
             }
         }
         curTermBuffer = null;
     }
 }