public IToken evaluate(ICharacterScanner scanner) {
        int c = 0;

        if (scanner.getColumn() > 0) {
          scanner.unread();
          c = scanner.read();
          if (!Character.isWhitespace((char) c)) {
            return fDefaultToken;
          }
        }

        c= scanner.read();
        if (c != ICharacterScanner.EOF && fDetector.isWordStart((char) c)) {
            if (fColumn == UNDEFINED || (fColumn == scanner.getColumn() - 1)) {

                fBuffer.setLength(0);
                do {
                    if (!fDetector.isWordPart((char) c))
                        break;

                        fBuffer.append((char) c);
                        c= scanner.read();

                } while (c != ICharacterScanner.EOF);

                String buffer= fBuffer.toString().toLowerCase().trim();

                IToken token= (IToken)fWords.get(buffer);

                if (token != null) {
                    return token;
                    }

                if (fDefaultToken.isUndefined())
                    unreadBuffer(scanner);
                return fDefaultToken;
            }
        }