Extend your solution to exercise 2.21 to implement Wirth’s syntax error recovery mechanism (a) with global FOLLOW sets, as in Example C 2.45. (b) with local FOLLOW sets, as in Example C 2.47 (c) with avoidance of “starter symbol” deletion, as in Example C 2.48.

Data From Exercise 2.21:

Build a complete recursive descent parser for the calculator language. As output, have it print a trace of its matches and predictions.