ShuffleBag.cs

//https://gist.github.com/col000r/6658520
//but all the hard work done by mstevenson: https://gist.github.com/mstevenson/4050130

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class ShuffleBag<T> : ICollection<T>, IList<T>
{
	private List<T> data = new List<T> ();
	private int cursor = 0;
	private T last;

	/// <summary>
	/// Get the next value from the ShuffleBag
	/// </summary>
	public T Next ()
	{
		if (cursor < 1) {
			cursor = data.Count - 1;
			if (data.Count < 1)
				return default(T);
			return data[0];
		}
		int grab = Mathf.FloorToInt (Random.value * (cursor + 1));
		T temp = data[grab];
		data[grab] = this.data[this.cursor];
		data[cursor] = temp;
		cursor--;
		return temp;
	}

	//This Constructor will let you do this: ShuffleBag<int> intBag = new ShuffleBag<int>(new int[] {1, 2, 3, 4, 5});
	public ShuffleBag(T[] initalValues) {
		for (int i = 0; i < initalValues.Length; i++) {
			Add (initalValues[i]);
		}
	}
	public ShuffleBag() {} //Constructor with no values

	#region IList[T] implementation
	public int IndexOf (T item)
	{
		return data.IndexOf (item);
	}
	
	public void Insert (int index, T item)
	{
		cursor = data.Count;
		data.Insert (index, item);
	}
	
	public void RemoveAt (int index)
	{
		cursor = data.Count - 2;
		data.RemoveAt (index);
	}
	
	public T this[int index] {
		get {
			return data [index];
		}
		set {
			data [index] = value;
		}
	}
	#endregion
	
	
	
	#region IEnumerable[T] implementation
	IEnumerator<T> IEnumerable<T>.GetEnumerator ()
	{
		return data.GetEnumerator ();
	}
	#endregion
	
	#region ICollection[T] implementation
	public void Add (T item)
	{
		//Debug.Log (item);
		data.Add (item);
		cursor = data.Count - 1;
	}
	
	public int Count {
		get {
			return data.Count;
		}
	}
	
	public void Clear ()
	{
		data.Clear ();
	}
	
	public bool Contains (T item)
	{
		return data.Contains (item);
	}
	
	public void CopyTo (T[] array, int arrayIndex)
	{
		foreach (T item in data) {
			array.SetValue (item, arrayIndex);
			arrayIndex = arrayIndex + 1;
		}
	}
	
	public bool Remove (T item)
	{
		cursor = data.Count - 2;
		return data.Remove (item);
	}
	
	public bool IsReadOnly {
		get {
			return false;
		}
	}
	#endregion
	
	#region IEnumerable implementation
	IEnumerator IEnumerable.GetEnumerator ()
	{
		return data.GetEnumerator ();
	}
	#endregion
	
}