I spoke to one of the authors of re2j, a Google-internal port of the C++ re2 library. The intention was to open source it but they just haven't got around to it.
I may try and get Google to put re2j up on GitHub so you all can take a look. AFAIK it is heavily used in Google and it has an API that is largely compatible with java.util.regex. I know from personal experience that one can often benefit from re2j merely by replacing java.util.regex imports with the corresponding re2j imports. Regards, James On Feb 1, 2015 11:44 PM, "Thomas Neidhart" <thomas.neidh...@gmail.com> wrote: > 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 > >
