Skip to main content

Optimizing Your Regular Expressions

Regular expressions will backtrack.  That's an unfortunate thing about them because backtracking can be slow.    And in certain (rare) cases the performance can become so awful that executing the regular expression against a relatively short string could take over a minute.  There's a good article about catastrophic backtracking over at regular-expressions.info.

And today I created a video about all of this called Regex Lesson 5: Optimization.  In the video I start with a very poorly written regular expression and make several improvements to it, using the benchmarking feature along the way.  By the end of the video I make the regular expression over 3 million times faster.

In addition, today's update to Regex Hero provides a little message in the event that you encounter a regular expression that takes over 10 seconds to evaluate...


And then last of all, I changed the benchmarking feature a bit.  In the past it would simply test your regular expression against your string and iterate over the matches.  It would repeat this process as many times as it could in 1 second.  The trouble was that it did the same thing even if you had the Replace or Split tab selected.  But now the benchmarking will actually do replacement operations when the Replace tab is selected, and it'll do split operations when the Split tab is selected.

Comments

Popular posts from this blog

Regex Hero for Windows 10 is Underway

Awhile back I began working on an HTML5 / JavaScript version of Regex Hero . However, it was a huge undertaking essentially requiring a complete rewrite of the entire application. I have not had enough time to dedicate to this lately. So I've begun again, this time rewriting Regex Hero to work in WPF. It'll be usable in Windows 10 and downloadable from the Microsoft Store. This is a much easier task that also has the advantage of running the .NET regex library from the application itself. This will allow for the same speedy experience of testing your regular expressions and getting instant feedback that Regex Hero users have always enjoyed. I expect the first release to be ready in Q4 of 2019.

Silverlight 4 Coming in April, or Maybe Sooner

The exact release date has not been announced. But Visual Studio 2010 RTM is coming out in April and I think it's safe to assume that Silverlight 4 will be released no later than that. Each release of Silverlight has brought massive improvements over the previous version. And once again, Silverlight 4 does not disappoint. There is a long list of improvements but the ones that I think that will affect Regex Hero are as follows: RichTextBox My plan is to use this in place of all 4 major textboxes in Regex Hero. The new RichTextBox has built-in multiple undos & redos, so I can ditch my home-brewed code. It should be nice to use for syntax highlighting for the regular expressions I intend to create. It also has a built-in API to determine the pixel position of the text. I should be able to use this API and build a new highlighting scheme based off of it. This should do a couple things. First, I should be able to finally fix the problem I had with the ScrollViewer and

Installer for Desktop version of Regex Hero

As Firefox just dropped support for Silverlight I really needed a solution for Regex Hero. So I created an installer for it. It's still Silverlight, but by using the installer you can install it directly to your computer and never need to open it in a browser. If you visit regexhero.net/tester and don't have a browser that supports Silverlight (IE is the only one left), then you'll see download links for 64-bit and 32-bit versions of the installer. When you install it you'll see a link over on the right hand side that says "Activate Regex Hero". This process connects your desktop version of Regex Hero with your online account. So if you're a licensed user this is how you'll gain access to all of those licensed features. Note: Currently there will be a security warning when you try to run either one of these installers. I'm in the process of obtaining a code signing certificate and will update them as soon as possible. You may be wondering a