using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Windows;

using System.Diagnostics.CodeAnalysis;



namespace Microsoft.Research.DynamicDataDisplay.DataSources

{

	/// <summary>

	/// Empty data source - for testing purposes, represents data source with 0 points inside.

	/// </summary>

	public class EmptyDataSource : IPointDataSource

	{

		#region IPointDataSource Members



		public IPointEnumerator GetEnumerator(DependencyObject context)

		{

			return new EmptyPointEnumerator();

		}



		[SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]

		private void RaiseDataChanged()

		{

			if (DataChanged != null)

			{

				DataChanged(this, EventArgs.Empty);

			}

		}



		public event EventHandler DataChanged;



		#endregion



		private sealed class EmptyPointEnumerator : IPointEnumerator

		{

			public bool MoveNext()

			{

				return false;

			}



			public void GetCurrent(ref Point p)

			{

				// nothing to do

			}



			public void ApplyMappings(DependencyObject target)

			{

				// nothing to do

			}



			public void Dispose() { }

		}

	}

}