WordPress: Better Internal Link Search modifier to limit search results to a particular post type.

gistfile1.php

<?php
/**
 * Search for a post type.
 *
 * <code>-cpt:{post_type} {query}</code>
 */
function bils_cpt_search( $results, $args ) {
	$search_args = array(
		'post_status'    => 'any',
		'post_type'      => $args['modifier'][1],
		'paged'          => $args['page'],
		'posts_per_page' => $args['per_page'],
		's'              => $args['s'],
	);	
	
	$posts = get_posts( $search_args );
	if ( $posts ) {
		foreach ( $posts as $post ) {
			$results[] = array(
				'title'     => get_the_title( $post->ID ),
				'permalink' => get_permalink( $post->ID ),
				'info'      => get_post_type( $post->ID ),
			);
		}
	}

	return $results;
}
add_filter( 'better_internal_link_search_modifier-cpt', 'bils_cpt_search', 10, 2 );

/**
 * Add the help entry for searching CPTs.
 */
function bils_cpt_search_help( $results ) {
	$results['cpt'] = array(
		'title'     => '<strong>-cpt:{post_type} {query}</strong></span><span class="item-description">Search for posts of a particular post type.</span>',
		'permalink' => home_url( '/' ),
		'info'      => 'Local',
	);
	
	asort( $results );
	
	return $results;
}
add_filter( 'better_internal_link_search_modifier_help', 'bils_cpt_search_help' );