LINQ Join Complex Condition

LinqJoinComplexCondition.cs

        public static IEnumerable<TResult> Join<TOuter, TInner, TResult>(
            this IEnumerable<TOuter> outer,
            IEnumerable<TInner> inner,
            Func<TOuter, TInner, bool> condition,
            Func<TOuter, TInner, TResult> resultSelector)
        {
            return from outerItem in outer
                   from innerItem in inner
                   where condition(outerItem, innerItem)
                   select resultSelector(outerItem, innerItem);
        }