class1.cs

来自DoFactory的设计模式, 由于是本人根据已有代码创建,没有NETOptimized项

// Iterator pattern -- Real World example  

using System;
using System.Collections;

namespace DoFactory.GangOfFour.Iterator.RealWorld
{

    // MainApp test application 

    class MainApp
    {
        static void Main()
        {
            // Build a collection 
            Collection collection = new Collection();
            collection[0] = new Item("Item 0");
            collection[1] = new Item("Item 1");
            collection[2] = new Item("Item 2");
            collection[3] = new Item("Item 3");
            collection[4] = new Item("Item 4");
            collection[5] = new Item("Item 5");
            collection[6] = new Item("Item 6");
            collection[7] = new Item("Item 7");
            collection[8] = new Item("Item 8");

            // Create iterator 
            Iterator iterator = new Iterator(collection);

            // Skip every other item 
            iterator.Step = 2;

            Console.WriteLine("Iterating over collection:");

            for (Item item = iterator.First();
              !iterator.IsDone; item = iterator.Next())
            {
                Console.WriteLine(item.Name);
            }

            // Wait for user 
            Console.Read();
        }
    }

    class Item
    {
        string name;

        // Constructor 
        public Item(string name)
        {
            this.name = name;
        }

        // Property 
        public string Name
        {
            get { return name; }
        }
    }

    // "Aggregate" 

    interface IAbstractCollection
    {
        Iterator CreateIterator();
    }

    // "ConcreteAggregate" 

    class Collection : IAbstractCollection
    {
        private ArrayList items = new ArrayList();

        public Iterator CreateIterator()
        {
            return new Iterator(this);
        }

        // Property 
        public int Count
        {
            get { return items.Count; }
        }

        // Indexer 
        public object this[int index]
        {
            get { return items[index]; }
            set { items.Add(value); }
        }
    }

    // "Iterator" 

    interface IAbstractIterator
    {
        Item First();
        Item Next();
        bool IsDone { get; }
        Item CurrentItem { get; }
    }

    // "ConcreteIterator" 

    class Iterator : IAbstractIterator
    {
        private Collection collection;
        private int current = 0;
        private int step = 1;

        // Constructor 
        public Iterator(Collection collection)
        {
            this.collection = collection;
        }

        public Item First()
        {
            current = 0;
            return collection[current] as Item;
        }

        public Item Next()
        {
            current += step;
            if (!IsDone)
                return collection[current] as Item;
            else
                return null;
        }

        // Properties 
        public int Step
        {
            get { return step; }
            set { step = value; }
        }

        public Item CurrentItem
        {
            get
            {
                return collection[current] as Item;
            }
        }

        public bool IsDone
        {
            get
            {
                return current >= collection.Count ? true : false;
            }
        }
    }
}