An Example of AsyncTaskMethodBuilder State Machine

using System;
using System.Runtime.CompilerServices;
using System.Threading.Tasks;

async Task Main()
{
	Task<int> task = CreateTask();
	int result = await task;
}

Task<int> CreateTask()
{
	// Create an asynchronous task method builder
	AsyncTaskMethodBuilder<int> builder = AsyncTaskMethodBuilder<int>.Create();

	// Get the state machine from the builder
	var stateMachine = new AsyncStateMachine(builder);

	// Set the builder to the awaiting state
	stateMachine.MoveNext();
	// Return the asynchronous task
	return builder.Task;
}

// Define the asynchronous state machine
struct AsyncStateMachine : IAsyncStateMachine
{
	private AsyncTaskMethodBuilder<int> _builder;
	private int _result;

	public AsyncStateMachine(AsyncTaskMethodBuilder<int> builder)
	{
		_builder = builder;
		_result = 0;
	}

	public void MoveNext()
	{
		try
		{
			// Perform an asynchronous operation, here it simulates a delay of 2 seconds
			Task.Delay(2000).Wait();

			// Set the result of the asynchronous task
			_result = 42;
			// Set the result, indicating task completion
			_builder.SetResult(_result);
		}
		catch (Exception ex)
		{
			// Exception handling
			_builder.SetException(ex);
		}
	}

	public void SetStateMachine(IAsyncStateMachine stateMachine)
	{
		// Not used, no handling needed
	}
}