XML properties sorter

sortxml.groovy

if (args.length == 0) {
    println("Usage: groovy sortxml.groovy messages.xml [key]")
    println("read from STDIN: groovy sortxml.groovy - [key]")
    System.exit(0)
}

def input = args[0] == '-'
    ? System.in
    : new File(args[0]).newInputStream()
def key = args.size() > 1 ? args[1] : 'key'

def parser = new XmlParser()
parser.setFeature("http://apache.org/xml/features/disallow-doctype-decl", false)
parser.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false)

input.withStream { stream ->
    def rootNode = parser.parse(stream)
    rootNode.children().sort(true) {it.attribute(key)}

    def printer = new XmlNodePrinter(preserveWhitespace:true)
    printer.print(rootNode)
}