Perl, etc has these "?"-prefix modifiers/codes/whatever. Precisely which does emacs have (and NOT have)?

[dkcombs@panix.com (David Combs)]

Subj:  Perl, etc has these "?"-prefix modifiers/codes/whatever.  
       Precisely which does emacs have (and NOT have)?


Please, someone, make an ascii or html table or even plain text 
list of all these neat "new" non-standard ops that perl and
even php and ruby etc seem to have now, comparing them
to what Emacs has or don't have.

Also point to any .el-files that upgrade that stuff.

---

Friedl's book "Mastering Regular Expresisions", both editions, 
covered Emacs re its regexp ability.  Very Nice!

Now there's A NEW REGEXP BOOK (also O'Reilly) a "COOKBOOK" on regexps, 
and covers, with examples and also pointed-out differences --
for a whole bunch of systems: perl, php, ruby, ... <I forget, but there's
a bunch of them>, but does NOT (DAMNIT!) even MENTION emacs!

Note: the credits say thanks to Friedl (maybe also Ilya, I 
forget) for suggestions on the various drafts.


So you see a nifty regexp in that book, and you want to try
it in emacs --- what a bear, trying to convert it into
something that emacs understands.


What say, some guru in emacs regexps?  (Ilya?  Friedl? ...)


Thanks!

David