Non-destructive, conditional migration for Laravel

non-destructive_migrations.php

<?php

use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class Zones extends Migration {

	/**
	 * Run the migrations.
	 *
	 * @return void
	 */
	public function up()
	{
		if ( Schema::hasTable('zones') ) : 
		  Schema::table('zones', function($table) {
  		  $this->_zones($table);
  		});
		else:
		  Schema::create('zones', function($table) {
  		  $this->_zones($table);
  		});
		endif;
	}

	/**
	 * Reverse the migrations.
	 *
	 * @return void
	 */
	public function down()
	{
		Schema::dropIfExists('zones');
	}
	
	private function _zones($table) {
  	
                $table->increments('id');
		$table->string('code')->index();
		$table->string('name');

		$table->integer('parent_id')->unsigned();
		$table->foreign('parent_id')->references('id')->on('zones');
	}

}