Regex: help to finish a regex in rubular

Question

I need a help to finish a Perl Regex to the context below:

[a-zA-Z:]

------------------------------------------
I have                      I need
------------------------------------------
> str(datasets::ris$)       datasets::ris
> plot(datasets::iris$      datasets::iris
str(datasets::iris$)        datasets::iris
plot(datasets::iris$        datasets::iris
str(iris$)                  iris
plot(iris$                  iris
plot(IRIs$                  IRIs
iris$                       iris
------------------------------------------

http://rubular.com/r/kyLAy679Ql

Thanks,

Answer 1

You can use this regex with an optional match and capturing group. Your desired text is available in captured group #1:

/(?:[^(\n]*\()?([a-zA-Z:]+)/

Rubular Demo

Answer 2

The results are at http://rubular.com/r/IgInzqrwwX

You just need to add a lookahead to your regex [a-zA-Z:]+(?=\s*\$)