add_icomoon_classes.php

<?php
/**
 * Adds necessary CSS classes for full star, half star and empty star ratings. Note it does
 * not need to actually be a star.
 * 
 * @param unknown $icon_classes
 * @param unknown $icon_font_library
 * @return string
 */
function my_add_icomoon_classes( $icon_classes, $icon_font_library ) {
	if ( $icon_font_library == 'icomoon-faces' ) {
		$icon_classes['star_full'] = 'icon-smile mrp-star-full';
		$icon_classes['star_hover'] = 'icon-smile mrp-star-hover';
		$icon_classes['star_half'] = 'icon-neutral mrp-star-half';
		$icon_classes['star_empty'] = 'icon-sad mrp-star-empty';
	}
	return $icon_classes;
}
add_filter( 'mrp_icon_classes', 'my_add_icomoon_classes', 10, 2 );