Oops forgot the /u on the regexp in the example. On Wed, Oct 7, 2015 at 10:06 AM, Erik Corry <[email protected]> wrote:
> Your proposal for look-behind relies on being able to count the match > length of the look-behind in order to step back that far. This presupposes > that atoms like . and character classes have a fixed length. > > However, with the /u flag, the . and some character classes can be either > 1 or two code units. This means you don't know how far to step back. This > needs to be fixed in a way that is not incompatible with the "correct" .NET > way of doing things. > > Eg matching /a.(?<!x..)/ against "xa😹" (x, a, > cat-face-with-tears-of-joy, which is a surrogate pair). The back reference > has an apparent width of 3, so we step back 3 code units, but that hits the > 'a', not the 'x' and so the back reference fails to spot the 'x'. > > > On Sun, Oct 4, 2015 at 1:52 PM, Nozomu Katō <[email protected]> wrote: > >> Apparently my proposal for adding the look-behind assertions to RegExp >> has been in trouble. I would like to ask anyone for help. >> >> The following story is what I know about the proposal after my previous >> post: >> >> I created a pull request for the proposal in July and sent an email to >> Brendan Eich asking if I can put his name as a champion: >> https://github.com/tc39/ecma262/pull/48 >> >> I have not received a reply to my email, but I received a notification >> email in September that replying to the pull request, the proposal was >> moved to stage 0. Today, however, I just noticed that the proposal had >> been dropped from stage 0, stating "RegExp lookbehind has no champion". >> https://github.com/tc39/ecma262/commits/master/stage0.md (Oct 4, 2015) >> >> I am uncertain about what happened. Does this mean that Brendan Eich is >> no longer a champion or did not take a champion on from the beginning or >> ...? >> >> >> Regards, >> Nozomu >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/es-discuss >> > >
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