On Sat, Mar 17, 2012 at 2:28 PM, Andrea Giammarchi <[email protected]> wrote: > I would simply apply same logic we have already for the look ahead ... or > you think that would cause problems?
I'm not sure it even makes sense. ES RegExps are backtracking based, and it makes a difference in which order alternatives are tried. Greedy matching is defined in terms of number of repetitions, not length of the match. All of these are defined in a way that assumes left-to-right matching. Example: Take the RegExp /(?<((?:aa|aaa)+))b/ where (?< ... ) delimits the look-behind. and try matching it on the string "xaaaaaaaaab". Then tell me how many a's are captured by the capturing group, and why :) The most "intuitive" interpretation would be a reverse implementation of the normal matching algorithm, i.e., "backwards matching", but that would likely duplicate the entire RegExp semantics (or parameterize it by a direction). Any attempt to use the normal (forward) semantics and then try to find an earlier point to start it at is likely to be either flawed or effectively unpredictable to users. And you will probably never achieve that /(<re>)$/ and /(?<(re))$/ always capture the same substring :) /L _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
