Question

I am looking for a PHP parser that can do this.

{tag} Replace the tag with text coming from a function

{tag(params)} It must support params

{tag({tag(params)},{tag(params)})} It must support nesting

{tag()?

else

} It must support Tests

{$tag=value} It must support varriables

Does anyone know of a parser that can do this?

Or maybe you know how I can create one. I have tried to do this with preg, but it seems impossible to create nesting.

Smarty seems to be a bit to big, and I don’t know if you can disable all the extra functionality it has. I only need the functionality that I have listed above.

In smarty you’re able to write PHP code and I don’t like that. {php} {/php}
So if I’am going to use that I need to be able to turn it of.

I’m going to use it with CodeIgniter.

Answer 1

To incorporate nesting in your regular expressions you have to use recursive patterns (?R). This matches whole pattern.

To find outermost {}-s in text (possibly with some other {} inside of them) you should use expression like this:

/{([^{}]*(?R))*[^{}]+}/

You can read about (?R) here: http://pl2.php.net/manual/en/regexp.reference.recursive.php

There is a construct {((?>[^{}]+)|(?R))*} suggested there. Maybe more efficient than the one I built.