add iterator pattern exmaple

add iterator pattern exmaple

Assets/Behavioral Patterns/Iterator Pattern/Example2/IteratorExample2.cs

@@ -0,0 +1,148 @@
+//-------------------------------------------------------------------------------------
+//	IteratorExample2.cs
+//-------------------------------------------------------------------------------------
+
+using UnityEngine;
+using System.Collections;
+using System.Collections.Generic;
+
+
+/* Iterator provides uniform way to access different collections of objects
+ * If you get an Array, ArrayList, Hashtable of objects, you pop out an iterator for each and treat them the same
+ * 
+ * This provides a uniform way to cycle through different collections
+ * 
+ * You can also write polymorphic code because you can refer to each collection of objects
+ * because they'll implement the same interface
+ * */
+
+
+public class IteratorExample2 : MonoBehaviour
+{
+	void Start ( )
+	{
+        // creating the collections and adding some songs:
+        SongsOfThe70s song70s = new SongsOfThe70s();
+        song70s.AddSong("song title", "song artist", 1974);
+        song70s.AddSong("song title2", "song artist2", 1978);
+
+        SongsOfThe80s song80s = new SongsOfThe80s();
+        song80s.AddSong("song title 80s", "song artist 80s", 1985);
+        song80s.AddSong("song title2 80s", "song artist2 80s", 1989);
+
+        // because of the iterator pattern we can loop through both types
+        // of collections the same simple way and don't have to bother
+        // with what type of collection the object stores:
+
+        IEnumerator songsOfThe70sIterator = song70s.GetIterator();
+        while (songsOfThe70sIterator.MoveNext())
+        {
+            SongInfo info = (SongInfo)songsOfThe70sIterator.Current;
+            Debug.Log("Song 70s: " + info.ToString());
+        }
+
+        IEnumerator songsOfThe80sIterator = song80s.GetIterator();
+        while (songsOfThe80sIterator.MoveNext())
+        {
+            SongInfo info = (SongInfo)songsOfThe80sIterator.Current;
+            Debug.Log("Song 80s: " + info.ToString());
+        }
+    }
+
+
+
+    // just a sample object to hold some arbitrary information for demonstration
+    public class SongInfo
+    {
+        public string songName { get; protected set; }
+
+        public string bandName { get; protected set; }
+
+        public int yearReleased { get; protected set; }
+
+        public SongInfo(string songName, string bandName, int yearReleased)
+        {
+            this.songName = songName;
+            this.bandName = bandName;
+            this.yearReleased = yearReleased;
+        }
+
+        public string ToString()
+        {
+            return this.songName + " - " + this.bandName + " : " + this.yearReleased.ToString();
+        }
+    }
+
+
+
+    // Iterator Interface
+    public interface SongIterator
+    {
+        IEnumerator GetIterator();
+    }
+
+
+
+    // These two classes implement the iterator
+    public class SongsOfThe70s : SongIterator
+    {
+        // here it is a list
+        protected List<SongInfo> bestSongs;
+
+        public SongsOfThe70s()
+        {
+            bestSongs = new List<SongInfo>();
+        }
+
+        public void AddSong(string name, string artist, int year)
+        {
+            SongInfo song = new SongInfo(name, artist, year);
+            bestSongs.Add(song);
+        }
+
+        //about yeild return :http://www.jb51.net/article/54810.htm
+        // heart
+        public IEnumerator GetIterator()
+        {
+            foreach (SongInfo song in bestSongs)
+                yield return song;
+            yield break;
+        }
+    }
+
+    public class SongsOfThe80s : SongIterator
+    {
+        // here we have an array
+        protected SongInfo[] bestSongs;
+
+        public SongsOfThe80s()
+        {
+            bestSongs = new SongInfo[0];
+        }
+
+        public void AddSong(string name, string artist, int year)
+        {
+            SongInfo song = new SongInfo(name, artist, year);
+            // just for the sake of easyness of appending something we will convert the array to a list
+            List<SongInfo> newSongs = new List<SongInfo>(bestSongs);
+            // add a new element
+            newSongs.Add(song);
+            // and convert it back to an array
+            bestSongs = newSongs.ToArray();
+        }
+
+        // heart
+        public IEnumerator GetIterator()
+        {
+            foreach (SongInfo song in bestSongs)
+                yield return song;
+            yield break;
+        }
+    }
+
+
+
+}
+
+
+