public static IEnumerable <TSource> Union <TSource>(
this IEnumerable <TSource> first,
IEnumerable <TSource> second,
IEqualityComparer <TSource> comparer = null) => Defer(() =>
{
LinqToObjects.HashSet <TSource> hashSet = new LinqToObjects.HashSet <TSource>(comparer);
return(first.Where(hashSet.Add).Concat(second.Where(hashSet.Add)));
});
public static IEnumerable <TSource> Intersect <TSource>(
this IEnumerable <TSource> first,
IEnumerable <TSource> second,
IEqualityComparer <TSource> comparer = null) => Defer(() =>
{
LinqToObjects.HashSet <TSource> hashSet = new LinqToObjects.HashSet <TSource>(comparer);
second.Iterate(secondValue => hashSet.Add(secondValue));
return(first.Where(hashSet.Remove));
});
public static IEnumerable <TSource> Except <TSource>(
this IEnumerable <TSource> first,
IEnumerable <TSource> second,
IEqualityComparer <TSource> comparer = null) => Defer(() =>
{
comparer = comparer ?? EqualityComparer <TSource> .Default;
LinqToObjects.HashSet <TSource> hashSet = new LinqToObjects.HashSet <TSource>(comparer);
foreach (TSource secondValue in second)
{
hashSet.Add(secondValue);
}
return(first.Where(hashSet.Add));
});
public static IEnumerable <TSource> Distinct <TSource>
(this IEnumerable <TSource> source, IEqualityComparer <TSource> comparer = null) => Defer(() =>
{
LinqToObjects.HashSet <TSource> hashSet = new LinqToObjects.HashSet <TSource>(comparer);
return(source.Where(hashSet.Add));
});
