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/* examples/xml/phonebook/phonebook3.scala */
package phonebook
object phonebook3 {
import scala.xml.{Elem, Node, Text}
import scala.xml.Utility.view
import scala.xml.PrettyPrinter
import Node.NoAttributes
/* finds entry for Name, Where, changes it, or adds if not present */
def change ( phonebook: Node, Name: String, Where: String, newPhone: String ) = {
/** returns true if this element's first child is the right 'name'
* x is treated a if it was a singleton sequence here.
*/
def hasName ( x: Seq[Node] ) = x(0).child.elements.next match {
case <name>{ Text(Name) }</name> => true
case _ => false
}
/** returns true if this element has the right 'where' attribute
* y is treated a if it was a singleton sequence here.
* n.attribute(s) is the same as n.attributes.get(s)
*/
def hasWhere ( y: Node ) = y.attribute("where") match {
case Some(Text(Where)) => true
case None => false
}
/** returns true if this element has the right 'where' attribute
* the apply method of MetaData (n.attributes) returns raw a
* sequence of nodes.
*/
def hasWhere2 ( y: Node ) = y.attributes("where") match {
case null => false
case Text(Where) => true
case _ => false
}
/** walks through tree, returns changed/copied updated tree */
def copyOrChange ( ch: Iterator[Node] ):List[Node] = {
for( val c <- ch ) yield c match {
case x @ <entry>{ ch1 @ _* }</entry> if hasName( x ) =>
val it = ch1.elements;
val nameElem:Seq[Node] = it.next; // grab 'name' element
val ch2 = nameElem concat copyOrChange( it ); // concat with updated seq
if( ch1 == ch2 ) // not present: add as first entry
<entry>
<name>{ Name }</name>
<phone where={ Where }>{ newPhone }</phone>
{ ch1 }
</entry>
else // was present and changed
<entry>
{ ch2 }
</entry>
case y @ <phone>{ _* }</phone> if hasWhere( y ) =>
Console.println("c = "+c);
<phone where={ Where }>{ newPhone }</phone>
case _ =>
Console.println("c = "+c);
Console.println("c.attributes= "+c.attributes);
c
}
}.toList ; // for ... yield ... returns Iterator, convert to list
// decompose phonebook, apply updates
phonebook match {
case <phonebook>{ ch @ _* }</phonebook> =>
<phonebook>{ copyOrChange( ch.elements ) }</phonebook>
}
}
val pb2 =
change( phonebook1.labPhoneBook, "John", "work", "+41 55 555 55 55" );
val pp = new PrettyPrinter( 80, 5 );
def main( args:Array[String] ) = {
Console.println("---before---");
Console.println( pp.format( phonebook1.labPhoneBook ));
Console.println("---after---");
Console.println( pp.format( pb2 ));
}
}
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