//Reflective Visitor
// Ako zelimo da dodamo novi Visit objekat,moramo da izmenimo
// Visitor interface,a potom i  implementiramo sam metod u svakom od
// Visitora.
//
// Resenje je u  Reflective Visitoru.Sa njim nam je potreban samo jedan  metod
//u  Visitor interfejsu - visit(Object).  Svi ostali metodi visit()  
// mogu se dodati kasnije 


import java.lang.reflect.Method;


//hijerarhija elementa 

interface Element {
   public void accept( ReflectiveVisitor v );
}
class This implements Element {
   public void   accept( ReflectiveVisitor v ) { v.visit( this ); }
   public String thiss()                       { return "Ovaj el"; }
}
class That implements Element {
   public void   accept( ReflectiveVisitor v ) { v.visit( this ); }
   public String that()                        { return "Onaj el"; }
}
class TheOther implements Element {
   public void   accept( ReflectiveVisitor v ) { v.visit( this ); }
   public String theOther()                    { return "Inace el"; }
}


//hijerarhija operacije

abstract class ReflectiveVisitor {
  abstract public void visit( Object o );

  public void visitTheOther( TheOther e ) {
    System.out.println( "ReflectiveVisitor: Operacija nad " + e.theOther() );
  }

  // 1. Potraga za  visitElementClassName() u tekucoj klasi
  // 2. Potraga za visitElementClassName() u nadklasama
  // 3. Potraga za  visitElementClassName() u interfejsima
  // 4. Potraga za visitObject() u tekucoj klasi
  
  protected Method getMethod( Class c ) {
    Class  newc = c;
    Method m    = null;
    while (m == null  &&  newc != Object.class) {
      String method = newc.getName();
      method = "visit" + method.substring( method.lastIndexOf('.') + 1 );
      try {
        m = getClass().getMethod( method, new Class[] { newc } );
      } catch (NoSuchMethodException ex) {
        newc = newc.getSuperclass();
    } }
    if (newc == Object.class) {
      // System.out.println( "Pretraga interfejsa" );
      Class[] interfaces = c.getInterfaces();
      for (int i=0; i < interfaces.length; i++) {
        String method = interfaces[i].getName();
        method = "visit" + method.substring( method.lastIndexOf('.') + 1 );
        try {
          m = getClass().getMethod( method, new Class[] { interfaces[i] } );
        } catch (NoSuchMethodException ex) { }
    } }
    if (m == null)
      try {
        m = getClass().getMethod( "visitObject", new Class[] { Object.class } );
      } catch (Exception ex) { }
    return m;
} }

class UpVisitor extends ReflectiveVisitor {
  public void visit( Object o ) {
    try {
      getMethod( o.getClass() ).invoke( this, new Object[] { o } );
    } catch (Exception ex) {
      System.out.println( "UpVisitor -nema odgovarajuceg  visit() metoda" );
  } }
  public void visitThis( This e ) {
    System.out.println( "UpVisitor: Izvrsiti Up nad " + e.thiss() );
  }
  public void visitObject( Object e ) {
    System.out.println( "UpVisitor- generisanje visitObject() metoda" );
} }

class DownVisitor extends ReflectiveVisitor {
  public void visit( Object o ) {
    try {
      getMethod( o.getClass() ).invoke( this, new Object[] { o } );
    } catch (Exception ex) {
      System.out.println( "DownVisitor: bez odgovarajuceg visit() metoda" );
  } }
  public void visitThat( That e ) {
    System.out.println( "DownVisitor: Down izvsen nad " + e.that() );
} }


class Visitor3 {
  public static void main( String[] args ) {
    Element[]    list = { new This(), new That(), new TheOther() };
    UpVisitor    up   = new UpVisitor();
    DownVisitor  down = new DownVisitor();
    for (int i=0; i < list.length; i++)
      list[i].accept( up );
    for (int i=0; i < list.length; i++)
      list[i].accept( down );
} }