WP7 Zip

gistfile1.cs

//Throws exception if number of items in the collection are different.
public static IEnumerable<R> Zip<T, U, R>(this IEnumerable<T> first, IEnumerable<U> second, Func<T, U, R> selector)
{
    var enumerator1 = first.GetEnumerator();
    var enumerator2 = second.GetEnumerator();
    while (true)
    {
        var move1 = enumerator1.MoveNext();
        var move2 = enumerator2.MoveNext();
        if (move1 != move2)
        {
            throw new InvalidOperationException("Zip collections contain different number of items.");
        }
        if (!move1)
        {
            yield break;
        }
        yield return selector(enumerator1.Current, enumerator2.Current);
    }
}

// Does not throw an exception if counts are different, uses the minimum.
public static IEnumerable<R> Zip<T, U, R>(this IEnumerable<T> first, IEnumerable<U> second, Func<T, U, R> selector)
{
	var enumerator1 = first.GetEnumerator();
	var enumerator2 = second.GetEnumerator();
	while (enumerator1.MoveNext() && enumerator2.MoveNext())
	{
		yield return selector(enumerator1.Current, enumerator2.Current);
	}
}