/// <summary>
/// Creates a KeyEqualityComparer based on the current key comparer that
/// in addition checks for equality based the value returned by the key selector.
/// </summary>
/// <typeparam name="TKey">The type of the value returned by the key selector.</typeparam>
/// <param name="keySelector">The delegate used to select the next key.</param>
/// <returns>
/// A KeyEqualityComparer based on the current key comparer that
/// in addition checks for equality based the value returned by the key selector.
/// </returns>
/// <exception cref="System.ArgumentNullException">The key selector is null.</exception>
public KeyEqualityComparer <T> And <TKey>(Func <T, TKey> keySelector)
{
if (keySelector == null)
{
throw new ArgumentNullException(nameof(keySelector));
}
var comparer = new CompoundKeyEqualityComparer <T>();
comparer.Add(this);
comparer.Add(new TypedKeyEqualityComparer <T, TKey>(keySelector, EqualityComparer <TKey> .Default));
return(comparer);
}
public void Add(KeyEqualityComparer <T> comparer)
{
CompoundKeyEqualityComparer <T> compoundComparer = comparer as CompoundKeyEqualityComparer <T>;
if (compoundComparer == null)
{
_comparers.Add(comparer);
}
else
{
_comparers.AddRange(compoundComparer._comparers);
}
}
/// <summary>
/// Creates a KeyEqualityComparer based on the current key comparer that
/// in addition checks for equality based the value returned by the key selector.
/// </summary>
/// <typeparam name="TKey">The type of the value returned by the key selector.</typeparam>
/// <param name="keySelector">The delegate used to select the next key.</param>
/// <param name="keyComparer">The equality comparer to use to compare the keys.</param>
/// <returns>
/// A KeyEqualityComparer based on the current key comparer that
/// in addition checks for equality based the value returned by the key selector.
/// </returns>
/// <exception cref="System.ArgumentNullException">The key selector is null.</exception>
/// <exception cref="System.ArgumentNullException">The key comparer is null.</exception>
public KeyEqualityComparer <T> And <TKey>(Func <T, TKey> keySelector, IEqualityComparer <TKey> keyComparer)
{
if (keySelector == null)
{
throw new ArgumentNullException("keySelector");
}
if (keyComparer == null)
{
throw new ArgumentNullException("keyComparer");
}
CompoundKeyEqualityComparer <T> comparer = new CompoundKeyEqualityComparer <T>();
comparer.Add(this);
comparer.Add(new TypedKeyEqualityComparer <T, TKey>(keySelector, keyComparer));
return(comparer);
}
