/// <summary>
/// Creates a key comparer.
/// </summary>
/// <typeparam name="T">The type of object being compared.</typeparam>
/// <typeparam name="TKey">The type of key objects being compared.</typeparam>
/// <param name="this">The equality comparer builder.</param>
/// <param name="selector">The key selector. May not be <c>null</c>.</param>
/// <param name="comparerFactory">The definition of the key comparer. May not be <c>null</c>.</param>
/// <param name="specialNullHandling">A value indicating whether <c>null</c> values are passed to <paramref name="selector"/>. If <c>false</c>, then <c>null</c> values are considered less than any non-<c>null</c> values and are not passed to <paramref name="selector"/>. This value is ignored if <typeparamref name="T"/> is a non-nullable type.</param>
/// <returns>A key comparer.</returns>
public static IFullEqualityComparer <T> EquateBy <T, TKey>(this EqualityComparerBuilderFor <T> @this, Func <T, TKey> selector, Func <EqualityComparerBuilderFor <TKey>, IEqualityComparer <TKey> > comparerFactory, bool specialNullHandling = false)
{
_ = comparerFactory ?? throw new ArgumentNullException(nameof(comparerFactory));
var comparer = comparerFactory(EqualityComparerBuilder.For <TKey>());
return(@this.EquateBy(selector, comparer, specialNullHandling));
}
/// <summary>
/// Creates a key comparer.
/// </summary>
/// <typeparam name="T">The type of object being compared.</typeparam>
/// <typeparam name="TKey">The type of key objects being compared.</typeparam>
/// <param name="this">The equality comparer builder.</param>
/// <param name="selector">The key selector. May not be <c>null</c>.</param>
/// <param name="keyComparer">The key comparer. Defaults to <c>null</c>. 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 <paramref name="selector"/>. If <c>false</c>, then <c>null</c> values are considered less than any non-<c>null</c> values and are not passed to <paramref name="selector"/>. This value is ignored if <typeparamref name="T"/> is a non-nullable type.</param>
/// <returns>A key comparer.</returns>
public static IFullEqualityComparer <T> EquateBy <T, TKey>(this EqualityComparerBuilderFor <T> @this, Func <T, TKey> selector, IEqualityComparer <TKey> keyComparer = null, bool specialNullHandling = false)
{
return(new SelectEqualityComparer <T, TKey>(selector, keyComparer, specialNullHandling));
}
/// <summary>
/// Gets the reference equality comparer for this type.
/// </summary>
public static IFullEqualityComparer <T> Reference <T>(this EqualityComparerBuilderFor <T> @this)
where T : class
{
return(ReferenceEqualityComparer <T> .Instance);
}
/// <summary> /// Gets the default equality comparer for this type. /// </summary> public static IFullEqualityComparer <T> Default <T>(this EqualityComparerBuilderFor <T> @this) => (IFullEqualityComparer <T>)EqualityComparerHelpers.NormalizeDefault <T>(null);
/// <summary> /// Gets the null equality comparer for this type, which evaluates all objects as equivalent. /// </summary> public static IFullEqualityComparer <T> Null <T>(this EqualityComparerBuilderFor <T> @this) => NullComparer <T> .Instance;
/// <summary>
/// Creates a key comparer.
/// </summary>
/// <typeparam name="T">The type of object being compared.</typeparam>
/// <typeparam name="TKey">The type of key objects being compared.</typeparam>
/// <param name="this">The equality comparer builder.</param>
/// <param name="selector">The key selector. May not be <c>null</c>.</param>
/// <param name="comparerFactory">The definition of the key comparer. May not be <c>null</c>.</param>
/// <param name="specialNullHandling">A value indicating whether <c>null</c> values are passed to <paramref name="selector"/>. If <c>false</c>, then <c>null</c> values are considered less than any non-<c>null</c> values and are not passed to <paramref name="selector"/>. This value is ignored if <typeparamref name="T"/> is a non-nullable type.</param>
/// <returns>A key comparer.</returns>
public static IFullEqualityComparer <T> EquateBy <T, TKey>(this EqualityComparerBuilderFor <T> @this, Func <T, TKey> selector, Func <EqualityComparerBuilderFor <TKey>, IEqualityComparer <TKey> > comparerFactory, bool specialNullHandling = false)
{
var comparer = comparerFactory(EqualityComparerBuilder.For <TKey>());
return(@this.EquateBy(selector, comparer, specialNullHandling));
}
