//GNU General Public License version 2 (GPLv2)
//http://dotwayutilities.codeplex.com/license
using System.Collections.Generic;
namespace Dotway.BuildTasks.Utils
{
/// <summary>
/// Compares two sequences.
/// </summary>
/// <typeparam name="T">Type of item in the sequences.</typeparam>
/// <remarks>
/// Compares elements from the two input sequences in turn. If we
/// run out of list before finding unequal elements, then the shorter
/// list is deemed to be the lesser list.
/// </remarks>
public class EnumerableComparer<T> : IComparer<IEnumerable<T>>
{
/// <summary>
/// Object used for comparing each element.
/// </summary>
private readonly IComparer<T> comp;
/// <summary>
/// Create a sequence comparer using the default comparer for T.
/// </summary>
public EnumerableComparer()
{
comp = Comparer<T>.Default;
}
/// <summary>
/// Create a sequence comparer, using the specified item comparer
/// for T.
/// </summary>
/// <param name="comparer">Comparer for comparing each pair of
/// items from the sequences.</param>
public EnumerableComparer(IComparer<T> comparer)
{
comp = comparer;
}
#region IComparer<IEnumerable<T>> Members
/// <summary>
/// Compare two sequences of T.
/// </summary>
/// <param name="x">First sequence.</param>
/// <param name="y">Second sequence.</param>
public int Compare(IEnumerable<T> x, IEnumerable<T> y)
{
using (IEnumerator<T> leftIt = x.GetEnumerator())
using (IEnumerator<T> rightIt = y.GetEnumerator())
{
while (true)
{
bool left = leftIt.MoveNext();
bool right = rightIt.MoveNext();
if (!(left || right)) return 0;
if (!left) return -1;
if (!right) return 1;
int itemResult = comp.Compare(leftIt.Current, rightIt.Current);
if (itemResult != 0) return itemResult;
}
}
}
#endregion
}
}
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