using System.Collections.Generic; using System.Runtime.CompilerServices; namespace System.Collections.Frozen { [NullableContext(1)] [Nullable(new byte[] { 0, 1, 1 })] internal sealed class EmptyFrozenDictionary<TKey, [Nullable(2)] TValue> : FrozenDictionary<TKey, TValue> { private protected override TKey[] KeysCore => Array.Empty<TKey>(); private protected override TValue[] ValuesCore => Array.Empty<TValue>(); private protected override int CountCore => 0; internal EmptyFrozenDictionary(IEqualityComparer<TKey> comparer) : base(comparer) { } [return: Nullable(new byte[] { 0, 1, 1 })] private protected override Enumerator GetEnumeratorCore() { return new Enumerator(Array.Empty<TKey>(), Array.Empty<TValue>()); } [return: IsReadOnly] private protected override ref TValue GetValueRefOrNullRefCore(TKey key) { return ref Unsafe.NullRef<TValue>(); } } }