Iterator Design Pattern

Programming/Design Patterns 2007. 2. 21. 10:54
// Iterator interface //

interface Iterator{
public function hasNext():Boolean;
public function next():Object;
}

// Aggregate interface //

interface Aggregate{
public function iterator():Iterator;
}

// Book class //

class Book{
private var name:String = "";
public function Book(name:String){
this.name = name;
}
public function getName():String{
return name;
}
}


// BookShelfIterator class //

class BookShelfIterator implements Iterator{
private var bookShelf:BookShelf;
private var index:Number;
private var book:Book;
public function BookShelfIterator(bookShelf:BookShelf){
this.bookShelf = bookShelf;
this.index = 0;
}
public function hasNext():Boolean{
if(this.index < bookShelf.getLength()){
return true;
}else{
return false;
}
}
public function next():Object{
this.book = bookShelf.getBookAt(this.index);
this.index++;
return this.book;
}
}



// BookShelf class//



class BookShelf implements Aggregate{
private var books:Array;
private var last:Number = 0;
public function BookShelf(){
this.books = new Array();
}
public function getBookAt(index:Number):Book{
return books[index];
}
public function appendBook(book:Book):Void{
this.books[last] = book;
last++;
}
public function getLength():Number{
return last;
}
public function iterator():Iterator{
return new BookShelfIterator(this);
}
}



// Main class //

class Main{
private var bookShelf:BookShelf;
private var it:Iterator;
private var book:Book;
public function Main(){
init();
}
public function init(){
this.bookShelf = new BookShelf();
this.bookShelf.appendBook(new Book("Around the World in 80 Days"));
this.bookShelf.appendBook(new Book("Bible"));
this.bookShelf.appendBook(new Book("Cinderella"));
this.bookShelf.appendBook(new Book("Daddy-Long-Legs"));
this.it = bookShelf.iterator();
while(it.hasNext()){
this.book = Book(it.next());
trace(""+this.book.getName());
}
}
}
    

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