code: @Override
  	public boolean isOverlapping(ConstantRange r) {
  		if (!(r instanceof VarcharConstantRange))
  			throw new IllegalArgumentException();
  		if (!isValid() || !r.isValid())
  			return false;
  		VarcharConstantRange sr = (VarcharConstantRange) r;
  		VarcharConstant rh = sr.high;
  		boolean rhi = sr.highIncl;
  		if (!low.equals(NEG_INF)
  				&& ((lowIncl && ((rhi && rh.compareTo(low) < 0) || (!rhi && rh
  						.compareTo(low) <= 0))) || (!lowIncl && rh
  						.compareTo(low) <= 0)))
  			return false;
  		VarcharConstant rl = sr.low;
  		boolean rli = sr.lowIncl;
  		if (!high.equals(INF)
  				&& ((highIncl && ((rli && rl.compareTo(high) > 0) || (!rli && rl
  						.compareTo(high) >= 0))) || (!highIncl && rl
  						.compareTo(high) >= 0)))
  			return false;
  		return true;
  	}
docs: /*
  Range operations.