/// <summary>
/// Checks a state's starting state
/// </summary>
/// <param name="state">Specifies state</param>
private void CheckStartingState(MartyState state)
{
// Check if state is null.
if (state == null)
{
throw new ArgumentNullException("Cannot check the starting state of a null state.");
}
// Check if state's starting state is null.
if (state.StartingState == null)
{
// Leave.
return;
}
// Check if state has children.
if (state.Children != null && state.Children.Count == 0)
{
throw new FormatException(string.Format("A state cannot have a starting state if it has no children; State = {0}, Invalid Starting State = {1}.",
state.Name,
this.GetState(state.StartingState).Name));
}
// Check if starting state is one of the states children.
if (!state.IsChild(state.StartingState))
{
throw new FormatException(string.Format("A state cannot have a starting state that isn't one of its children; State = {0}, Invalid Starting State = {1}.",
state.Name,
this.GetState(state.StartingState).Name));
}
}
/// <summary>
/// Process exit event
/// </summary>
/// <param name="destinationState">Specifies destination state</param>
internal void Exit(MartyState destinationState)
{
// Start event processing.
this.ProcessingHandler(true);
// Block transitioning.
this.BlockTransitionHandler();
MartyState parentState = this.StateLookupHandler(this.ParentState);
// Check if destination state is a descendant of this state.
if (!this.IsDescendant(destinationState))
{
// Process this state's exit event.
this.EventHandler(MartyBase.Exit, null);
// Check if this state's parent needs to process its exit event.
if (!(this.ParentState == null || parentState.IsTopState || this.IsSibling(destinationState)))
{
// Process parent's exit event.
parentState.EventHandler(MartyBase.Exit, null);
}
}
// Stop event processing.
this.ProcessingHandler(false);
}
internal bool IsDescendant(MartyState state)
{
if (this.IsChild(state))
{
return(true);
}
return(this.children.Any(child => this.StateLookupHandler(child).IsDescendant(state)));
}
internal bool IsSibling(MartyState state)
{
if (this.Id == state.Id)
{
return(false);
}
return(this.ParentState == state.ParentState);
}
/// <summary>
/// Prepares Top state for use
/// </summary>
private void PrepareTopState()
{
// Initailize top state.
this.Top = new MartyState(MartyConstants.TopStateName);
// Register Top state.
this.RegisterState(this.Top, this.TopHandler, null);
// Throw an exception if starting state is null.
if (this.TopStartingState == null)
{
throw new NullReferenceException(string.Format("The starting state for the {0} state cannot be null.", MartyConstants.TopStateName));
}
// Set starting state for Top state.
this.Top.StartingState = this.TopStartingState.Id;
}
/// <summary>
/// Changes states during state transition
/// </summary>
/// <param name="destinationState">Specifies destination state</param>
private void ChangeState(MartyState destinationState)
{
// Mark that state transition is in progress.
this.IsTransitioning = true;
// Initialize old state as current state.
MartyState oldState = this.CurrentState;
// Check if current state is null.
if (this.CurrentState != null)
{
this.CurrentState.Exit(destinationState);
}
// Set current state to be destination state.
this.CurrentState = destinationState;
// Check if starting state of current state is null.
if (this.CurrentState.StartingState != null)
{
// Process start events until the actual starting state has been reached.
do
{
// Process start event.
this.CurrentState.Start();
// Set current state's starting state as current state.
this.CurrentState = this.GetState(this.CurrentState.StartingState);
} while (this.CurrentState.StartingState != null);
}
// Check if old state is null.
if (oldState != null)
{
// Process entry event if it isn't null.
this.CurrentState.Enter(oldState);
}
// Store that transitioning has ended.
this.IsTransitioning = false;
// Run next instruction.
this.RunNextInstruction();
}
/// <summary>
/// Transitions to a registered state
/// </summary>
/// <param name="destination">Specifies destination state</param>
protected void TransitionTo(MartyState destination)
{
// Check if destination state is null.
if (destination == null)
{
// Throw an exception if destination state is null.
throw new InvalidOperationException(string.Format("Cannot transition to a null state."));
}
// Throw an exception if a designation state is not registered.
if (!this.states.Keys.Any(key => key == destination.Id))
{
throw new InvalidOperationException(string.Format("The state {0} hasn't been registered.", destination.Name));
}
// Throw an exception if transitioning is blocked in current state.
if (!this.AllowTransitions)
{
throw new InvalidOperationException(string.Format("Transitions cannot be made during Start or Exit events. See state {0}.", this.CurrentState.Name));
}
// Check if current state equals destination.
if (this.CurrentState == destination)
{
// Leave.
return;
}
// Check if state is busy.
if (this.IsBusy)
{
// Queue instruction.
this.instructions.Enqueue(new MartyInstruction(MartyInstructionTypes.Transition, destination.Id, null));
// Leave.
return;
}
// Change state.
this.ChangeState(destination);
}
/// <summary>
/// Performs entry action
/// </summary>
/// <param name="source">Specifies source state</param>
internal void Enter(MartyState source)
{
// Mark that the event is being processed.
this.ProcessingHandler(true);
MartyState parentState = this.StateLookupHandler(this.ParentState);
// Check if parent's entry event needs processing.
if (!(null == parentState || parentState.IsTopState || source.IsAncestor(parentState) || this.IsDescendant(source)))
{
// Process parent's entry event.
parentState.EventHandler(MartyBase.Entry, null);
}
// Check if source is NOT a descendant.
if (!this.IsDescendant(source))
{
// Process
this.EventHandler(MartyBase.Entry, null);
}
// Release processing.
this.ProcessingHandler(false);
}
internal bool IsChild(MartyState state)
{
return(this.children.Any(child => child == state.Id));
}
internal bool IsAncestor(MartyState state)
{
return(!state.IsTopState && state.IsDescendant(this));
}
/// <summary>
/// Registers a state
/// </summary>
/// <param name="state">Specifies state</param>
/// <param name="eventHandler">Specifies event handler</param>
/// <param name="parentState">Specifies parent</param>
/// <param name="startingState">Specifies starting state</param>
protected void RegisterState(MartyState state, EventHandler eventHandler, MartyState parentState = null, MartyState startingState = null)
{
// Check if state is null.
if (state == null)
{
throw new ArgumentNullException("Cannot register a null state.");
}
// Check if state is being set as its own parent.
if (state == parentState)
{
throw new ArgumentException(string.Format("State {0} cannot be its own parent.", state.Name));
}
// Check if state is being set as its own starting state.
if (state == startingState)
{
throw new ArgumentException(string.Format("State {0} cannot be its own starting state.", state.Name));
}
// Try adding state to dictionary.
try
{
// Add state to dictionary.
this.states.Add(state.Id, state);
}
// Catch argument exceptions.
catch (Exception exception)
{
// Throw exception with more detailed error message.
throw new InvalidOperationException(string.Format("An exception occurred during state registration: {0}; Exception: {1}", state.Name, exception.Message));
}
// Add state to parent state's children.
if (parentState != null)
{
if (state.IsTopState)
{
throw new InvalidOperationException(string.Format("Cannot set '{0}' state as parent state. Use NULL instead.", MartyConstants.TopStateName));
}
parentState.AddChild(state.Id);
}
else
{
if (!state.IsTopState)
{
parentState = this.Top;
parentState.AddChild(state.Id);
}
}
// Set state's properties.
state.StartingState = startingState == null ? default(long?) : startingState.Id;
state.ParentState = parentState == null ? default(long?) : parentState.Id;
state.EventHandler = eventHandler;
state.StateLookupHandler = this.GetState;
state.ProcessingHandler = this.SetProcessing;
state.BlockTransitionHandler = this.BlockTransitioning;
}