exuberant ctags with PHP in Vim

One reason I've heard PHP developers use for adopting an IDE when developing is the ability to click on a class or function name and jump to the declaration. Sounds like magic, and it's definitely something I've desired.

One way I get around it is by adopting PEAR coding standards for naming my classes. Since they define a one-to-one mapping of class name to the file system (substitute the underscore character (_) with the directory separator), I can usually very quickly and easily open a class file, particularly if I start in the base directory of the project install.

Today, however, I found exuberant ctags, a library which can be used to generate an index file mapping language objects to source files and the line in the source file where they are declared. Contrary to its name, it's not just for the C language; it currently supports 33 different programming languages, including PHP.

I decided to try it out on the Zend Framework core library today. At first run, it was pretty useful. However, it was only mapping classes, and, in addition, only those defined with the single word 'class' — abstract classes and interfaces were entirely left out. So, I looked into the documentation to see if I could change the behaviour.

And, being a Unix program, of course I could. First off, you can add functions to the items it indexes with a simple flag. Additionally, you can use POSIX regular expressions to refine what it searches.

I whipped up the following script to create my tags index:

cd /path/to/framework/library
exec ctags-exuberant -f ~/.vim/mytags/framework \
-h \".php\" -R \
--exclude=\"\.svn\" \
--totals=yes \
--tag-relative=yes \
--PHP-kinds=+cf \
--regex-PHP='/abstract class ([^ ]*)//c/' \
--regex-PHP='/interface ([^ ]*)//c/' \
--regex-PHP='/(public |static |abstract |protected |private )+function ([^ (]*)//f/'

This script creates the tag index in the file $HOME/.vim/mytags/framework. It scans for PHP files recursively through the tree, excluding any files found in a .svn directory (I'm using a checkout from the subversion repository). The file paths in the index are created relative to the tags file; this was important, because if this wasn't provided, vim was unable to jump to the file, as it couldn't find it. --PHP-kinds=+cf tells it to index classes and functions. Next, I've got three regular expressions. The first tells it to match classes beginning with 'abstract class' as classes. The second tells it to match interfaces as classes. The last is so that PHP 5 methods, which begin with a visibility operator, to be matched as functions.

Once the index file is generated (it takes less than a second), all you need to do in vim is tell it to load it: :set tags=~/.vim/mytags/framework. At this point, you can do all sorts of fun stuff. Place the cursor on a class name or method name, anywhere in it, and hit Ctrl-], and you'll jump to the file and line of its declaration; Ctrl-T then takes you back. If you change the invocation to Ctrl-W ], it will split the current window and open the declaration in the new pane. (If you're familiar with how help works with Vim, this should seem pretty familiar.)

One more reason to stick with Vim for your PHP editing needs. :-)