Re: RFC 145 (v2) Brace-matching for Perl Regular Expressions

[Nathan Torkington]

Steven W McDougall writes:
> To express nesting, you need a context-free grammer; to recognize
> nested constructs, you need a stack machine.
> 
> Going from REs to CFGs is a huge jump in the complexity of Perl, and
> trading in state machines for stack machines is a huge jump in the
> complexity of the interpreter.

5.6's regular expressions have (??{ ... }) to permit recursion and
$^R to maintain state through the parsing. 

Nat