Take-Home Points

• Key benefits of PEGs:

• Simplicity, formalism, analyzability of CFGs

• Closer match to syntax practices

  • More expressive than deterministic CFGs (LL/LR)
  • More of the “right kind” of expressiveness: prioritized choice, greedy rules, syntactic predicates
  • Unlimited lookahead, backtracking

• Linear-time parsing for any PEG