I'll put a 'RegExp Find and Replace' action function on the list. The Apple API for regular expressions is not available for Snow Leopard so the function may be a noop for that OS.

Wow, great! Thanks! (I'm not interested in SL anyway 😉 )

There are numerous issues with the extract due largely to the fact that Yate action functions do not comprise a full programming language. However, since the Apple regular expression implementation is based on the extremely powerful ICU implementation, I think the replace can be used to do pretty much everything. The ICU specification can be found at:

http://userguide.icu-project.org/strings/regexp

The replacement text is templated so that you can extract all or individual capture groups. Using this technique you could construct a 'new string' with components delimited so that you could use the other Yate text based functions to extract individual matched components. So as an example if your pattern had two capture groups you could have a replace template of:

"<endleft>$1<endmiddle>$2<endright>"

This would give you access you to:
everything before the first capture group
the first capture group
everything between the two groups
etc.

While not as aesthetic for those rarer times you want to extract, it will work and does not require the use of incremental variables. If you use a common delimiter you could even use a Repeat With function to iterate between the components.

The function as is now planned will support options (outside the pattern) for Match All, Match First, Match Last, Case Insensitive. Further, both the pattern and replace template will perform a pre-scan for \v constructs doing the appropriate properly escaped replacements prior to the matching process.

Unless you're on Snow Leopard you can use the Regular Expression Replace function. 🙂