/*Date: Thu, 10 Mar 2005 15:59:40 +0000 (UTC)
From: John B. Clements <clements @ ccs neu edu>
Newsgroups: ccs.courses.csu213
Subject: class code 2005-03-07
*/
/*
+-------------------+
| Airport           |
+-------------------+
| String name       |
| AirportList dests |
+-------------------+

*/

// airport
class Airport {
  String name;
  AirportList dests;

  Airport(String name, AirportList dests) {
    this.name = name;
    this.dests = dests;
  }
  boolean same(Object other) {
    if (other instanceof Airport)
      return (this.name.equals(((Airport)other).name)) &&
             
             true;
    else
      return false;
  }

  void addFlight(Airport newDest){
    this.dests = new ALCons(newDest,this.dests);
  }
}

/*
          +-------------+              
          | AirportList |<------------+
          +-------------+             |
          +-------------+             |
                / \                   |
                ---                   |
                 |                    |
     -------------------              |
     |                 |              |
  +------+    +------------------+    |
  | ALMT |    | ALCons           |    |
  +------+    +------------------+    |
  +------+    | Airport first    |    |
              | AirportList rest |-+  |
              +------------------+ |  |
                                   |  |
                                   +--+

*/

abstract class AirportList {

  // is 'this' object extensionally equivalent to 'other'?
  abstract boolean same(Object other);
}

class ALMT extends AirportList {


  ALMT() {
  }
  boolean same(Object other) {
    if (other instanceof ALMT)
      return true;
    else
      return false;
  }
}

class ALCons extends AirportList {
  Airport first;
  AirportList rest;

  ALCons(Airport first, AirportList rest) {
    this.first = first;
    this.rest = rest;
  }
  boolean same(Object other) {
    if (other instanceof ALCons)
      return (this.first.same(((ALCons)other).first)) &&
             (this.rest.same(((ALCons)other).rest)) &&
             true;
    else
      return false;
  }
}

class Examples{

  Airport logan = new Airport("Logan",new ALMT());
  Airport manchester = new Airport("Manchester",new ALMT());
  Airport lax = new Airport("LAX",new ALMT());
  Airport denver = new Airport("Denver",new ALMT());

  boolean runTests(){
    this.denver.addFlight(this.logan);
    this.logan.addFlight(this.denver);
    return true;
  }     
  boolean t1 = runTests();

  boolean t2 = this.logan.dests.same(new ALCons(this.denver,new ALMT()));
 
  boolean t3 = this.logan.dests.same(new ALCons
                (new Airport("Denver",
                   new ALMT()),
                new ALMT()));

}