Queue<T>

// System.Queue — System.Core (decompiled from Larva HIR)

into namespace System
{
	/// First in, first out: Enqueue at the end, Dequeue from the front (a ring buffer).
	public class Queue<T>
	{
		T[] items;
		i32 head;
		i32 count;

		[NoInline]
		Grow()
		{
			T[] bigger = new T[items.Length * 2];
			loop (i32 i = 0..count)
				bigger[i] = items[(head + i) % items.Length];
			items = bigger;
			head = 0;
		}

		public:
			new()
			{
				items = new T[8];
			}

			Enqueue(T item)
			{
				if (count == items.Length)
					Grow();
				i32 at = head + count;
				if (at >= items.Length)
					at -= items.Length;
				items[at] = item;
				count++;
			}

			Dequeue() : T
			{
				if (count == 0)
					throw new InvalidOperationError("Dequeue on an empty queue");
				T item = items[head];
				items[head] = default(T);
				head++;
				if (head == items.Length)
					head = 0;
				count--;
				return item;
			}

			Peek() : T
			{
				if (count == 0)
					throw new InvalidOperationError("Peek on an empty queue");
				return items[head];
			}

			Clear()
			{
				loop (i32 i = 0..count)
					items[(head + i) % items.Length] = default(T);
				head = 0;
				count = 0;
			}

			i32 Count
			{
				get => count;
			}

			bool IsEmpty
			{
				get => count == 0;
			}
	}
}