//---------------------------------------------------------------------------
//
// <copyright file="EmptyEnumerable" company="Microsoft">
//    Copyright (C) Microsoft Corporation.  All rights reserved.
// </copyright>
// 
//
// Description: Empty enumerable
//
// History:  
//  11/11/2004  KenLai  :   Created
//
//---------------------------------------------------------------------------
using System;
using System.Collections;
 
namespace MS.Internal.Controls
{
    /// <summary>
    /// Returns an Enumerable that is empty.
    /// </summary>
    internal class EmptyEnumerable: IEnumerable
    {
        // singleton class, private ctor
        private EmptyEnumerable()
        {
        }
 
        IEnumerator IEnumerable.GetEnumerator()
        {
            return EmptyEnumerator.Instance;
        }
 
        /// <summary>
        /// Read-Only instance of an Empty Enumerable.
        /// </summary>
        public static IEnumerable Instance
        {
            get
            {
                if (_instance == null)
                {
                    _instance = new EmptyEnumerable();
                }
                return _instance;
            }
        }
 
        private static IEnumerable _instance;
    }
}