How to treat single newline as real line break in PHP Markdown?

Question

I was reading http://github.github.com/github-flavored-markdown/

I would like to implement that \"Newline modification\" in PHP Markdown:

Best I could think of

Answer 1

I've came up with the following solution, imitating most parts of the gfm newline behavior. It passes all the relevant tests on the page mentioned in the original post. Please note that the code below preprocesses markdown and outputs flavored markdown.

preg_replace('/(?