Backtracking Control Verbs

• (*PRUNE)

• • when backtracked into, the match fails at the current starting position.
  • similar to (?>...) except that prune is unary and not a bracketing construct. Thus you can write:
  • /A (? B | C (*PRUNE) ) D/
  • Can be used with (*FAIL) to find the longest match possible for every start position in the string.
  • /a+b?(?{print $&})(*PRUNE)(*FAIL)/