Regular expression matching unescaped paired brackets and nested function calls

Question

Here's the problem: given a string like

"<p>The price for vehicles {capitalize(pluralize(vehicle))} is {format_number(value, language)}</p><span>{employee_name}</span><span>\{do not parse me}</span>"

I need (1) a regex pattern in PHP that matches all values between un-escaped pairs of curly brackets and (2) another regex pattern that matches function calls and nested function calls (once the first pattern is matched). Of course, if I could use one regex only for both tasks that would be awesome.

By the way, I can't use Smarty, Twig or any other library - that's the only reason I have to build a parsing mechanism myself.

Thanks a ton!

Solution (1) A partial solution for the first problem can be found here. Basically, we use the regex

(?={((?:[^{}]++|{(?1)})++)})

and find the matches at index 1 of the resulting array.

It's partial because I still need to find a way of ignoring escaped braces, though.

(2) I'm considering the use of recursive regex, as suggested by Mario. Will post result here.

Thanks, guys!

Answer 1

Copying the answer from the comments in order to remove this question from the "Unanswered" filter:

This appears to be what you're looking for:

(?<!\\){([^(){}]+)\(((?:[^(){}]+|\(((?2))\))*)\)}

Link: http://www.regex101.com/r/uI4qN0

~ answer per Jerry

Note: For comparison - simply ignoring escaped braces is accomplished by adding a negative lookahead (?<!\\) to the beginning of the expression, like so:

(?<!\\)(?={((?:[^{}]++|{(?1)})++)})