function for comments shortcode

gistfile1.php

function phpcode($atts, $content = "") {
	return '<pre class="php">'.esc_attr($content).'</pre>';
}
function csscode($atts, $content = "") {
	return '<pre class="css">'.$content.'</pre>';
}
function htmlcode($atts, $content = "") {
	return '<pre class="html">'.esc_html($content).'</pre>';
}
function init_common_shortcodes() {
	add_shortcode('html', 'htmlcode');
	add_shortcode('php', 'phpcode');
	add_shortcode('css', 'csscode');
}

function init_comment_shortcodes() {
  remove_all_shortcodes();
  init_common_shortcodes();
  add_filter('comment_text', 'do_shortcode');
}

init_common_shortcodes();
add_filter('comments_template', 'init_comment_shortcodes');