/// <summary>
/// Initializes a new instance of the <see cref="SourceEqualityComparerBase{T,TSource}"/> class.
/// </summary>
/// <param name="source">The source comparer. If this is <c>null</c>, the default comparer is used.</param>
/// <param name="specialNullHandling">A value indicating whether <c>null</c> values are passed to <see cref="EqualityComparerBase{T}.DoGetHashCode"/> and <see cref="EqualityComparerBase{T}.DoEquals"/>. If <c>false</c>, then <c>null</c> values are considered not equal to any non-<c>null</c> values and are not passed to <see cref="EqualityComparerBase{T}.DoGetHashCode"/> nor <see cref="EqualityComparerBase{T}.DoEquals"/>.</param>
protected SourceEqualityComparerBase(IEqualityComparer <TSource> source, bool specialNullHandling)
: base(specialNullHandling)
{
_source = EqualityComparerHelpers.NormalizeDefault(source);
}
/// <summary>
/// Initializes a new instance of the <see cref="CompoundEqualityComparer<T>"/> class.
/// </summary>
/// <param name="source">The source comparer. If this is <c>null</c>, the default comparer is used.</param>
/// <param name="secondSource">The second comparer. If this is <c>null</c>, the default comparer is used.</param>
public CompoundEqualityComparer(IEqualityComparer <T>?source, IEqualityComparer <T>?secondSource)
: base(source, true)
{
_secondSource = EqualityComparerHelpers.NormalizeDefault(secondSource);
}