ValueQueue<T>
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.InteropServices;
namespace System.Text.Json
{
[StructLayout(LayoutKind.Auto)]
internal struct ValueQueue<T>
{
private byte _state;
private T _single;
private Queue<T> _multiple;
public void Enqueue(T value)
{
switch (_state) {
case 0:
_single = value;
_state = 1;
return;
case 1:
(_multiple ?? (_multiple = new Queue<T>())).Enqueue(_single);
_single = default(T);
_state = 2;
break;
}
_multiple.Enqueue(value);
}
public bool TryDequeue([MaybeNullWhen(false)] out T value)
{
switch (_state) {
case 0:
value = default(T);
return false;
case 1:
value = _single;
_single = default(T);
_state = 0;
return true;
default:
return _multiple.TryDequeue(out value);
}
}
}
}