/// <summary>
/// Produces the set intersection of two sequences, based on the specified key and key comparer.
/// </summary>
/// <typeparam name="TSource">The type of the elements of <c>source</c>.</typeparam>
/// <typeparam name="TKey">The type of the key used to test for equality between elements.</typeparam>
/// <param name="source">The first sequence.</param>
/// <param name="other">The second sequence.</param>
/// <param name="keySelector">A delegate that returns the key used to test for equality between elements.</param>
/// <param name="keyComparer">A comparer used to test for equality between keys.</param>
/// <returns>The set intersection of <c>source</c> and <c>other</c>, based on the specified key and key comparer.</returns>
public static IEnumerable <TSource> IntersectBy <TSource, TKey>(
this IEnumerable <TSource> source,
IEnumerable <TSource> other,
Func <TSource, TKey> keySelector,
IEqualityComparer <TKey> keyComparer = null)
{
var comparer = XEqualityComparer.By(keySelector, keyComparer);
return(source.Intersect(other, comparer));
}
public static IEnumerable <TSource> DistinctBy <TSource, TKey>(
[NotNull] this IEnumerable <TSource> source,
[NotNull] Func <TSource, TKey> keySelector,
IEqualityComparer <TKey>?keyComparer = null)
{
source.CheckArgumentNull(nameof(source));
keySelector.CheckArgumentNull(nameof(keySelector));
var comparer = XEqualityComparer.By(keySelector, keyComparer);
return(source.Distinct(comparer));
}
public static IEnumerable <TSource> ExceptBy <TSource, TKey>(
[NotNull] this IEnumerable <TSource> source,
[NotNull] IEnumerable <TSource> other,
[NotNull] Func <TSource, TKey> keySelector,
IEqualityComparer <TKey> keyComparer = null)
{
source.CheckArgumentNull(nameof(source));
other.CheckArgumentNull(nameof(other));
keySelector.CheckArgumentNull(nameof(keySelector));
var comparer = XEqualityComparer.By(keySelector, keyComparer);
return(source.Except(other, comparer));
}
