/*
Date: Mon, 14 Feb 2005 18:21:07 +0000 (UTC)
From: John B. Clements <clements@ccs.neu.edu>
Newsgroups: ccs.courses.csu213
Subject: Lecture code 2005-02-10 (monkeymangler.java)
*/

// mangles a monkey
interface MonkeyMangler {
  boolean mangle(int weight);
}

// A Mangler for monkeys under 100 lbs.
class UnderOneHundred implements MonkeyMangler {
  UnderOneHundred(){}

  boolean mangle(int weight){
    return (weight < 100);
  }
}


// A Mangler for monkeys over 200 lbs.
class OverTwoHundred implements MonkeyMangler {
  OverTwoHundred(){}

  boolean mangle(int weight){
    return (weight > 200);
  }
}



// lists of animals
abstract class LoA {

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

  // mangles a list of monkeys
  abstract LoA mangleMonkeys(MonkeyMangler mm);

}

// represent a list of animals
class MT extends LoA {

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


  LoA mangleMonkeys(MonkeyMangler mm){
    return new MT();
  }
}

class Cons extends LoA {
  Monkey first;
  LoA rest;

  Cons(Monkey first, LoA rest) {
    this.first = first;
    this.rest = rest;
  }
  boolean same(Object other) {
    if (other instanceof Cons)
      return (this.first.same(((Cons)other).first)) &&
             (this.rest.same(((Cons)other).rest)) &&
             true;
    else
      return false;
  }

  LoA mangleMonkeys(MonkeyMangler mm){
    if (mm.mangle(this.first.weight))
      return new Cons(this.first,this.rest.mangleMonkeys(mm));
    else
      return this.rest.mangleMonkeys(mm);
  }
}


// represent animals
abstract class Animal {

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

// represent monkeys
class Monkey extends Animal {
  int weight;

  Monkey(int weight) {
    this.weight = weight;
  }
  boolean same(Object other) {
    if (other instanceof Monkey)
      return (this.weight == ((Monkey)other).weight) &&
             true;
    else
      return false;
  }

}

// represent Elephants
class Elephant extends Animal {
  int numOfLegs;

  Elephant(int numOfLegs) {
    this.numOfLegs = numOfLegs;
  }
  boolean same(Object other) {
    if (other instanceof Elephant)
      return (this.numOfLegs == ((Elephant)other).numOfLegs) &&
             true;
    else
      return false;
  }
}

// represent a Hippopotamus
class Hippo extends Animal {
  int numOfHeads;

  Hippo(int numOfHeads) {
    this.numOfHeads = numOfHeads;
  }
  boolean same(Object other) {
    if (other instanceof Hippo)
      return (this.numOfHeads == ((Hippo)other).numOfHeads) &&
             true;
    else
      return false;
  }
}



class Examples{
  Examples(){}

  Monkey m1 = new Monkey(25);
  LoA l1 = new Cons(this.m1,new Cons(new Monkey(400),new MT()));

  //boolean s1 = (this.l1.onlyLittleMonkeys().same(new Cons(this.m1,new MT())));
  //boolean s2 = (this.l1.onlyBigMonkeys().same(new Cons(new Monkey(400),new MT())));

  boolean s3 = (this.l1.mangleMonkeys(new UnderOneHundred()).same(new Cons(this.m1,new MT())));

  }