On 02/02/2015 03:25 AM, sebb wrote: > I would not wish to move away from Java RE *unless* the RE syntax was > the same *and* the implementation was better performing *and* the > existing code suffered from poor performance. > > It might be OK if the alternate implementation was missing some > esoteric features, but I would be very wary of using any features that > were not in the Java implementation. > > The likelihood is that the Java implementation will (eventually) > become more performant, at which point it would be useful to be able > to revert to the Java version. > That requires a high degree of compatibilty to reduce the work involved. > > It might be more useful to produce a tool that detects inefficient RE > usage and suggests improvements.
I just know re2 a bit, but it is a trade-off: * linear-time evaluation vs. some features (e.g. backreferences) A comparison between different regular expression implementations can be found here: http://en.wikipedia.org/wiki/Comparison_of_regular_expression_engines I am pretty sure the regexp implementation in java will not change, simply because of backwards compatibility reasons, but such a library would be useful as in many cases you do not need these additional features but want to ensure that your regular expression will be evaluated in linear time. Thomas > > > On 1 February 2015 at 22:35, James Carman <ja...@carmanconsulting.com> wrote: >> To be clear, I am not advocating this approach. I was merely trying to >> illustrate what a nightmare such an endeavor would be. :) >> >> On Sunday, February 1, 2015, James Carman <ja...@carmanconsulting.com> >> wrote: >> >>> You would basically have to pick a canonical regex language if you want a >>> facade and be able to swap the regex library out. Most of them are very >>> similar but they are not the same. >>> >>> On Sunday, February 1, 2015, Gary Gregory <garydgreg...@gmail.com >>> <javascript:_e(%7B%7D,'cvml','garydgreg...@gmail.com');>> wrote: >>> >>>> I think we'll need some clear performance advantages documented as well as >>>> any compatibility issues. >>>> >>>> This begs for a facade API IMO. I would not want to recode my app just to >>>> test one vs. the other, it should be pluggable. >>>> >>>> Gary >>>> >>>> On Sat, Jan 31, 2015 at 10:58 AM, Benson Margulies <bimargul...@gmail.com >>>>> >>>> wrote: >>>> >>>>> So, once upon a time, there was a regex library here. It was retired, >>>>> presumably on the grounds that it was rendered obsolete by the JRE's >>>>> native support. >>>>> >>>>> However, the JRE's regular expressions have a pretty severe problem; >>>>> they have unbounded (or at least, very, very, bad) execution time for >>>>> some combinations of data and regex. >>>>> >>>>> To cope with this, we ported the Henry Spencer regular expression >>>>> library (as found in TCL) from C to Java. >>>>> >>>>> Thus: https://github.com/basis-technology-corp/tcl-regex-java >>>>> >>>>> Is anyone interested in this? Give or take the possible IP muddle of >>>>> the original C Code, I could grant it easily. >>>>> >>>>> --------------------------------------------------------------------- >>>>> To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org >>>>> For additional commands, e-mail: dev-h...@commons.apache.org >>>>> >>>>> >>>> >>>> >>>> -- >>>> E-Mail: garydgreg...@gmail.com | ggreg...@apache.org >>>> Java Persistence with Hibernate, Second Edition >>>> <http://www.manning.com/bauer3/> >>>> JUnit in Action, Second Edition <http://www.manning.com/tahchiev/> >>>> Spring Batch in Action <http://www.manning.com/templier/> >>>> Blog: http://garygregory.wordpress.com >>>> Home: http://garygregory.com/ >>>> Tweet! http://twitter.com/GaryGregory >>>> >>> > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org > For additional commands, e-mail: dev-h...@commons.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
