Where can I find a text parser like Google Plus?

Question

PHP

I recently noticed a very interesting way to format your own texts in google+
. They can use *bold* and _italic_ text, links are automatic, newlines are also automatic. And this is quite enough for me for my self-written cms. Only here the implementation is lame. I can't properly write a regular expression parser because I can't understand the logic of the google parser.
Can anyone help with the search for ready-made parsers (perhaps in js, perhaps in php)?

Answer 1

https://www.google.ru/search?q=markdown+php

Answer 2

Parsedown , for example. Here's a demo .