Lookaround Regex to manipulate Strings
Locked
Lookaround Regex to manipulate Strings
 
|
Hi Squeak Fans!
I have a short question regarding regular expressions in Squeak. I have the following problem: I have a fileName and I want to cut off its file extension (.jpg, .png etc.). To do this efficiently I wanted to use regular expressions with lookaround. So let's assume the following: | fileName | fileName := 'test.jpg'. fileName matchesRegex: '.+(=?.(jpg|jpeg|png))' I thought there is a possibility of returning the string without file extension through lookaround. Do you have any hints for me? Thanks guys! Regards, Hans ______________________________________________________ GRATIS für alle WEB.DE-Nutzer: Die maxdome Movie-FLAT! Jetzt freischalten unter http://movieflat.web.de _______________________________________________ Beginners mailing list [hidden email] http://lists.squeakfoundation.org/mailman/listinfo/beginners |
|
|
#sansPeriodSuffix can help or if you want only some extension: fileName regex: '.+(=?.(jpg|jpeg|png))' matchesDo: [:fname | newFileName:= fname sansPeriodSuffix]
you probably can do it only with regex but I don't know right now :) hth,
-- Cédrick _______________________________________________ Beginners mailing list [hidden email] http://lists.squeakfoundation.org/mailman/listinfo/beginners |
Re: Lookaround Regex to manipulate Strings
|
|
In reply to this post by Hans Gruber
Hans Gruber wrote:
> Hi Squeak Fans! > > I have a short question regarding regular expressions in Squeak. > > I have the following problem: > > I have a fileName and I want to cut off its file extension (.jpg, .png etc.). To do this efficiently I wanted to use regular expressions with lookaround. Using regular expressions may be convenient, it sure as hell isn't efficient. Much easier to use, e.g., fileName copyUpToLast: $. As for efficiency: [1 to: 10000 do:[:i| 'filename.jpg' matchesRegex: '.+(=?.(jpg|jpeg|png))' ]] timeToRun. => 2222 msecs [1 to: 10000 do:[:i| 'filename.jpg' copyUpToLast: $. ]] timeToRun. => 30 msecs So using regexp's is about 80x slower. Cheers, - Andreas > So let's assume the following: > > | fileName | > fileName := 'test.jpg'. > > fileName matchesRegex: '.+(=?.(jpg|jpeg|png))' > > I thought there is a possibility of returning the string without file extension through lookaround. > > Do you have any hints for me? > > Thanks guys! > > Regards, > Hans > ______________________________________________________ > GRATIS für alle WEB.DE-Nutzer: Die maxdome Movie-FLAT! > Jetzt freischalten unter http://movieflat.web.de _______________________________________________ Beginners mailing list [hidden email] http://lists.squeakfoundation.org/mailman/listinfo/beginners |
Re: Re: Lookaround Regex to manipulate Strings
|
|
In reply to this post by Hans Gruber
Hi Guys!
Thank you so much, this worked fine! Regards, Hans > Hans Gruber wrote: > > Hi Squeak Fans! > > > > I have a short question regarding regular expressions in Squeak. > > > > I have the following problem: > > > > I have a fileName and I want to cut off its file extension (.jpg, .png etc.). To do this efficiently I wanted to use regular expressions with lookaround. > > Using regular expressions may be convenient, it sure as hell isn't > efficient. Much easier to use, e.g., > > fileName copyUpToLast: $. > > As for efficiency: > > [1 to: 10000 do:[:i| > 'filename.jpg' matchesRegex: '.+(=?.(jpg|jpeg|png))' > ]] timeToRun. > => 2222 msecs > > [1 to: 10000 do:[:i| > 'filename.jpg' copyUpToLast: $. > ]] timeToRun. > => 30 msecs > > So using regexp's is about 80x slower. > > Cheers, > - Andreas > > > > So let's assume the following: > > > > | fileName | > > fileName := 'test.jpg'. > > > > fileName matchesRegex: '.+(=?.(jpg|jpeg|png))' > > > > I thought there is a possibility of returning the string without file extension through lookaround. > > > > Do you have any hints for me? > > > > Thanks guys! > > > > Regards, > > Hans > > ______________________________________________________ > > GRATIS für alle WEB.DE-Nutzer: Die maxdome Movie-FLAT! > > Jetzt freischalten unter http://movieflat.web.de > > _______________________________________________ > Beginners mailing list > [hidden email] > http://lists.squeakfoundation.org/mailman/listinfo/beginners > ________________________________________________________________________ Kostenlos tippen, täglich 1 Million gewinnen: zum WEB.DE MillionenKlick! http://produkte.web.de/go/08/ _______________________________________________ Beginners mailing list [hidden email] http://lists.squeakfoundation.org/mailman/listinfo/beginners |
Re: Lookaround Regex to manipulate Strings
|
|
Hans Gruber wrote:
> Hi Guys! > > Thank you so much, this worked fine! You're welcome. Do yourself a favor and browse around a little in the various String protocols. There's a *ton* of useful stuff like allButFirst:, allButLast:, copyUpTo:, copyUpToLast:, copyAfter:, copyAfterLast: etc. So for example: baseName := fileName allButLast: 4. "strips off .foo if you know it's 3 chars but copyUpToLast: is safer here" extension := fileName copyAfterLast: $. "gets the .extension" etc. Cheers, - Andreas > Regards, > Hans > >> Hans Gruber wrote: >>> Hi Squeak Fans! >>> >>> I have a short question regarding regular expressions in Squeak. >>> >>> I have the following problem: >>> >>> I have a fileName and I want to cut off its file extension (.jpg, .png etc.). To do this efficiently I wanted to use regular expressions with lookaround. >> Using regular expressions may be convenient, it sure as hell isn't >> efficient. Much easier to use, e.g., >> >> fileName copyUpToLast: $. >> >> As for efficiency: >> >> [1 to: 10000 do:[:i| >> 'filename.jpg' matchesRegex: '.+(=?.(jpg|jpeg|png))' >> ]] timeToRun. >> => 2222 msecs >> >> [1 to: 10000 do:[:i| >> 'filename.jpg' copyUpToLast: $. >> ]] timeToRun. >> => 30 msecs >> >> So using regexp's is about 80x slower. >> >> Cheers, >> - Andreas >> >> >>> So let's assume the following: >>> >>> | fileName | >>> fileName := 'test.jpg'. >>> >>> fileName matchesRegex: '.+(=?.(jpg|jpeg|png))' >>> >>> I thought there is a possibility of returning the string without file extension through lookaround. >>> >>> Do you have any hints for me? >>> >>> Thanks guys! >>> >>> Regards, >>> Hans >>> ______________________________________________________ >>> GRATIS für alle WEB.DE-Nutzer: Die maxdome Movie-FLAT! >>> Jetzt freischalten unter http://movieflat.web.de >> _______________________________________________ >> Beginners mailing list >> [hidden email] >> http://lists.squeakfoundation.org/mailman/listinfo/beginners >> > > > ________________________________________________________________________ > Kostenlos tippen, täglich 1 Million gewinnen: zum WEB.DE MillionenKlick! > http://produkte.web.de/go/08/ _______________________________________________ Beginners mailing list [hidden email] http://lists.squeakfoundation.org/mailman/listinfo/beginners |
«
Return to Squeak - Beginners
|
1 view|%1 views
| Free forum by Nabble | Edit this page |