On Thu, Nov 28, 2013 at 10:46 AM, John Cowan <xxxxxx@mercury.ccil.org> wrote:

Note that Java
has not only greedy and reluctant (= non-greedy), but also possessive
(notated *+, matches everything, never backtracks). I have been unable
to see the use of this, however.

This, unsurprisingly, is also originally from PCRE,

where PAT*+ a shortcut for (?>PAT*), available as

(atomic (* PAT)) in IrRegex.

It's an optimization technique to avoid exponential

backtracking, analogous to cut in Prolog. Thus

by definition it only makes sense in a specific

backtracking implementation.

Alex