It is nice. I'll have to play with this as well. Thanks again everyone. On Friday, February 2, 2018 at 5:49:15 PM UTC-6, johnbclements wrote: > > > > > On Feb 2, 2018, at 3:21 PM, Matthew Butterick <m...@mbtype.com > <javascript:>> wrote: > > > > > >> On Feb 2, 2018, at 10:23 AM, 'John Clements' via Racket Users < > racket...@googlegroups.com <javascript:>> wrote: > >> > >> This macro gets the names in much closer to the corresponding patterns > than matching by index, but it doesn’t actually embed the names into the > regexp. > > > > > > If you like keeping the names and patterns together, you could also > create an association list of the names and subpatterns, and iterate: > > > > #lang racket > > > > (define msg "2018-02-02T11:26:34 someuser some-computername01 > 233.194.20.110 something broke") > > (with-input-from-string msg > > (thunk > > (for/hash ([(name pat) (in-dict '((date . "[-\\dT:]+") > > (username . "\\w+") > > (hostname . "[-\\w\\d]+") > > (ip . "[\\d\\.]+") > > (message . ".+")))]) > > (values name (car (regexp-match (pregexp pat) > (current-input-port))))))) > > Oh, that’s nice. > > In fact, I’ll tell you what I *really* like about that; it could radically > simplify the irritating process of debugging regexps by breaking them in > various places to perform a binary search; you could instead provide a nice > error message specifying exactly which part of the regexp failed to match. > > One thing to be aware of is that you’d need to make sure that your regexp > still works without backtracking. If you broke #px”.*abc” into #px”.*” and > #px”abc”, it wouldn’t mean the same thing any more. > > John > > > > > > > '#hash((message . #" something broke") > > (date . #"2018-02-02T11:26:34") > > (username . #"someuser") > > (hostname . #"some-computername01") > > (ip . #"233.194.20.110")) > > > > -- > > You received this message because you are subscribed to the Google > Groups "Racket Users" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to racket-users...@googlegroups.com <javascript:>. > > For more options, visit https://groups.google.com/d/optout. > > > >
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