gamestatemachine

/// <summary>
/// Represents a hierarchical state machine to manage macro flow control in the game.
/// </summary>
public class GameStateMachine
{
    Stack<GameState> states;

    /// <summary>
    /// Gets the active game state.
    /// </summary>
    public GameState Current
    {
        get
        {
            if (states.Count == 0) return null;
            else return states.Peek();
        }
    }

    public void Update()
    {
        Current.Update();
    }

    public void Draw()
    {
        Current.Draw();
    }
}

/// <summary>
/// Represents a logical state of the game within the structure of a <see cref="GameStateMachine"/>.
/// </summary>
public abstract class GameState
{
    /// <summary>
    /// Allows the state to implement custom logic.
    /// </summary>
    public virtual void Update() { }
    /// <summary>
    /// Allows the state to implement custom rendering.
    /// </summary>
    public virtual void Draw() { }
}