#region Copyright And Revision History

/*---------------------------------------------------------------------------

	DiagonalVector.cs
	Copyright © 2002 Bill Menees.  All rights reserved.
	Bill@Menees.com

	Who		When		What
	-------	----------	-----------------------------------------------------
	BMenees	10.20.2002	Created.

-----------------------------------------------------------------------------*/

#endregion

using System;
using System.Diagnostics;

namespace Menees.DiffUtils
{
	/// <summary>
	/// Implements a vector from -MAX to MAX
	/// </summary>
	internal sealed class DiagonalVector
	{
		int m_iMax;
		int[] m_arData;

		public DiagonalVector(int N, int M)
		{
			int iDelta = N-M;

			//We have to add Delta to support reverse vectors, which are
			//centered around the Delta diagonal instead of the 0 diagonal.
			m_iMax = N+M+Math.Abs(iDelta);

			//Create an array of size 2*MAX+1 to hold -MAX..+MAX.
			m_arData = new int[2 * m_iMax + 1];
		}

		public int this[int iUserIndex]
		{
			get
			{
				return m_arData[GetActualIndex(iUserIndex)];
			}
			set
			{
				m_arData[GetActualIndex(iUserIndex)] = value;
			}
		}

		private int GetActualIndex(int iUserIndex)
		{
			int iIndex = iUserIndex + m_iMax;
			Debug.Assert(iIndex >= 0 && iIndex < m_arData.Length);
			return iIndex;
		}
	}
}