oembed-gist.php

<?php
/*
Plugin Name: WP Gist oEmbed
Plugin URI: https://laptrinh.senviet.org
Description: Embed source from gist.github.
Author: nguyenvanduocit
Version: 1.9.0
Author URI: http://nvduoc.senviet.org
*/

class sv_gist_oembed {
	private $regex = "/https:\\/\\/gist\\.github\\.com\\/([a-zA-Z0-9]*)\\/([a-z0-9]*)$/i";
	function __construct()
	{
		wp_embed_register_handler(
			'sv-gist-oembed',
			$this->regex,
			array( $this, 'handler' )
		);
	}

	public function handler( $matches, $attr, $url, $rawattr )
	{
		return sprintf('<script src="https://gist.github.com/%1$s/%2$s.js"></script>', $matches[1], $matches[2]);
	}

}
new sv_gist_oembed();