public static IEnumerable <T> Shuffle <T>(this IEnumerable <T> source, RandomIntBetween rng)
{
Contract.Requires <ArgumentNullException>(source != null);
Contract.Requires <ArgumentNullException>(rng != null);
Contract.Ensures(Contract.Result <IEnumerable <T> >() != null);
return(ShuffleIterator(source, rng));
}
/// <remarks>
/// Adapted from LukeH's answer on StackOverflow.
/// http://stackoverflow.com/users/55847/
/// http://stackoverflow.com/a/5807238/343238
/// </remarks>
private static IEnumerable <T> ShuffleIterator <T>(IEnumerable <T> source, RandomIntBetween rng)
{
var buffer = source.ToList();
for (var i = 0; i < buffer.Count; i++)
{
var j = rng(i, buffer.Count);
yield return(buffer[j]);
buffer[j] = buffer[i];
}
}
private static TestDelegate TestDelegate <T>(IEnumerable <T> source, RandomIntBetween rng)
{
return(() => Core.Extensions.ForIEnumerable.Shuffle(source, rng));
}
