add iterator pattern exmaple

add iterator pattern exmaple

Author: QianMo

Assets/Behavioral Patterns/Interpreter Pattern/Example2/InterpreterExample2.unity

@@ -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;
+ }
+ }
+
+
+
+}
+
+
+