StringBuilder version of java.util.regex.Matcher.append* (original) (raw)

Peter Levart peter.levart at gmail.com
Thu Mar 20 08:32:02 UTC 2014

On 03/19/2014 06:51 PM, Jeremy Manson wrote:

I'm told that the diff didn't make it. I've put it in a Google drive folder...

https://drive.google.com/file/d/0BGaXa6O4K5LY3Y0aHpranM3aEU/edit?usp=sharing Jeremy

Hi Jeremy,

Your factoring-out of expandReplacement() method exposed an opportunity to further optimize the code. Instead of creating intermediate StringBuilder instance for each expandReplacement() call, this method could append directly to resulting StringBuffer/StringBuilder, like in the following:

http://cr.openjdk.java.net/~plevart/jdk9-dev/MatcherWithStringBuilder/webrev.01/

Regards, Peter

On Wed, Mar 19, 2014 at 10:41 AM, Jeremy Manson <jeremymanson at google.com>wrote: Hi folks,

We've had this internally for a while, and I keep meaning to bring it up here. The Matcher class has a few public methods that take StringBuffers, and we've found it useful to add similar versions that take StringBuilders. It has two benefits: - Users don't have to convert from one to the other when they want to use the method in question. The symmetry is nice. - The StringBuilder variants are faster (if lock optimizations don't kick in, which happens in the interpreter and the client compiler). For interpreted / client-compiled code, we saw something like a 25% speedup on String.replaceAll(), which calls into this code. Any interest? Diff attached. Jeremy

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