Gist Shortcode Embed

Blog comments and forum posts are traditionally the worst place to post code, but unfortunately are the frequent hosts of code for developers like us.  Many developers choose to post links to more dev-friendly environments like GitHub instead, but there's a certain disconnect that comes with posting an external resource for something that would be much more useful in an internal capacity.  Using some server-side magic (PHP in this case) and regular expressions, we can utilize GitHub's Gist API to display external code within comments and forum posts as desired!

The PHP

There are two formats to detect:  shortcode [gist #####] format and simple gist link format:

/*
	Embed format: <script src="https://gist.github.com/4575399.js"></script>
*/

function embedGists($string) {
	$regex1 = '/https:\/\/gist.github.com\/(\d+)/';
	$regex2 = '/\[gist (\d+)\]/';
	$replace = '<script src="https://gist.github.com/${1}.js"></script>';

	// Find [gist ######] stuff
	$string = preg_replace($regex1, $replace, $string);
	$string = preg_replace($regex2, $replace, $string);

	return $string;
}

// Test string 
$string = 'lah blah<br />[gist 4575399]<br />And another: https://gist.github.com/4575399';
echo embedGists($string);

/* Provides:  

	lah blah<br /><script src="https://gist.github.com/4575399.js"></script><br />And another: <script src="https://gist.github.com/4575399.js"></script>

*/

Since GitHub is so popular and their gist embed is so useful, using their embed functionality is a logic choice.  Better yet is that detection and output is easy to implement.  Consider GitHub gist embedding as a viable option for your tech-oriented website -- your users will be grateful!