We are happy to announce the availability of my second Regular Expression webinar recording. It was a fun event, which I used to explain all the attendees a little bit more about the PCRE Regular Expression engine available in PHP and some other languages. I am covering some slightly advanced topics, like subpattern options, unicode and backtracking aka. greediness and performance.

You can watch these two recordings over on the Zend.com site:

• Black Magic with Regular Expressions
• Understanding Regular Expressions

Regular Expressions are the Swiss Army knife for searching through information for certain patterns. They have a wide arsenal of tools, some of which often go undiscovered or underutilized. Today I will show you some advanced tips for working with regular expressions.

They have it broken out into several tips including:

• Using Callbacks
• Lookahead and Lookbehind Assertions
• Filtering Patterns
• Named Subpatterns

There's also a section called "Don't Reinvent the Wheel" with a few handy expressions to do common things like parse [X]HTML and validating form input.

One backslash sequence that doesn't get much attention is K. What this handy little assertion does is match the position of whatever string comes before it in the pattern, then it in essence resets the match. At that point it starts a new match with whatever comes after K from the current location in the subject string.

They include a series of PHP code examples showing how use can use it to work around some of the issues with lookbehind assertions. They also include a few benefits and drawbacks of using them over lookbehinds.

I wanted to set up routes in such way that when a user requests a page, all requests for non-existing controllers/modules are directed to a specific controller (not the error controller). In other words, if we have controllers IndexController, FooController and PageController, anything but http://example.com/index and http://example.com/foo is directed to the PageController.

Using the Zend_Controller_Router_Route_Regex component he creates an expression that matches anything but the two allowed controllers and pushes them back over to the "page" controller. The new route is put in place via an addRoute call. He also shows how to use the Zend_Navigation component to manage the navigation structure for this application, defining a PHP array of the nested sitemap if the site.

Today for a good website's referencement in Google, it's necessary to have an URL rewriting. [...] If your application is based on ZF, we have a htaccess base file which will redirect all php files to the boostrap (what is the bootstrap ?), and ZF classes will manage all redirection rules. How to implement the URL rewriting with ZF classes ?

He sets up a config file (an ini file) with the routing instructions the framework will need to adhere to and shows how to get the application to include it and match against it for routing rules. His example sets a default route and several regular expression-based routes to remap requests right where they need to go.

At its most basic level, a regex can be considered a method of pattern matching or matching patterns within a string. In PHP the most oft used is PCRE or "Perl Compatible Regular Expressions". Here we will try to decypher the meaningless hieroglyphics and set you on your way to a powerful tool for use in your applications. Do not try to understand all this in a single sitting. Instead, take in a little and come back as you grasp various concepts.

He starts with simple string matching, showing how to get values from the middle, end and beginning of it then moves on to the next more powerful step - using meta characters. He outlines these as well as sequences and modifiers. There's plenty of examples here so there's almost no chance of getting lost.

It's a great tutorial that I'd recommend to anyone who things regular expressions are "just too hard" or it looking to figure out their power.

More than a half year after my last "Comfortable PHP editing with VIM" post, I take up this series again, although I decided to let it die in January. Sadly I did not find any time by now, to extend PDV (the PHP Documentor for VIM plugin) further than it's version 1.0.1, which is available through vim.org and on my SVN. Anyway, I collected a lot of (at least for me) helpful VIM tips, which I'd like to share here

The post contains tons of tips on subjects such as:

• Find matching brace
• Indenting and unindeting
• Emergency help
• Macros