Re: Alternative Syntax for Regular Expressions?

Jon Forrest wrote:


> I've been looking at some pretty hairy regular expressions (in Perl)
> recently that are virtually unreadable. The thought crossed my mind
> that maybe there are some alternatives to classic regular expression
> syntax out there. Note that I'm only talking about the syntax - it's
> hard to beat the semantics of regular expressions.
>
> Does anybody know of anything?


I've invented a few operators of my own.


a ^ b ==> a (b a)*
                                                great for extended CFGs
                                                Also, easy to construct a F.S.M. from.
                                                (IDList -> ID ^ ',' ';' )


a ^| b ==> a (a | b)*
                                                useful for writing scanners.
                                                  ( identifier --> CHAR ^| INT )


a% ==> (anything except a) immediately followed by a.
                                                    great operator for things like sed/grep/perl
                                                      I would think.


a @ b ==> (a | b | ab)
                                                      This is useful for reasons too difficult
to explain here.




I also like using {a} instead of a* and [a] instead of a?


So has anybody else invented or know of useful
non-standard regular expression operators?????




I also like the adea of extending regular expressions to include the $
operator where the $ operator stands for the extended regular
expression.


The result is a one production extended CFG.


e.g.


    ((abc)*$(def)) | ghi


    specifies the same language as
the one production grammar:


      Start ==> ((abc)* Start (def)) | ghi




(So you can beat the semantics of regular expressions :) )


Ralph Boland

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