Write down the drawback of top down parsing of backtracking.
Following are disadvantages of top down parsing of backtracking:
(i) Semantic actions can't be performed whereas making a prediction. The actions should be delayed till the prediction is identified to be a part of a successful parse.
(ii) Precise error reporting is impossible. A mismatch only triggers backtracking. A source string is identified to be erroneous just after all predictions have failed.