dir_to_array.php

<?php

/**
 * Function
 *
 * @param [string|null] $dir Directory
 * @return mixed
 */
function dir_to_array( $dir = null ) {
        $result = array();
        $cdir   = scandir( $dir );

        foreach ( $cdir as $key => $value ) {
                if ( ! in_array( $value, array( '.', '..' ), true ) ) {
                        if ( is_dir( $dir . DIRECTORY_SEPARATOR . $value ) ) {
                                $result[ $value ] = dir_to_array( $dir . DIRECTORY_SEPARATOR . $value );
                        } else {
                                $result[] = "{$dir}/$value";
                        }
                }
        }

        if ( ! is_array( $result ) ) {
                return array();
        }

        ksort( $result );
        return $result;
}

/**
 * Array flatten
 *
 * @param array $array Array
 *
 * @return array
 */
function array_flatten( $array ) {
        $return = array();
        foreach ( $array as $key => $value ) {
                if ( is_array( $value ) ) {
                        $return = array_merge( $return, array_flatten( $value ) );
                } else {
                        $return[ $key ] = $value;
                }
        }

        return $return;
}

var_dump( array_flatten( dir_to_array( 'includes' ) ) );