/// <summary>
/// Raises the <see cref="Exit"/> event.
/// </summary>
/// <param name="eventArgs">
/// <see cref="StateEventArgs"/> object that provides the arguments for the event.
/// </param>
/// <remarks>
/// <strong>Notes to Inheritors:</strong> When overriding <see cref="OnExit"/> in a derived
/// class, be sure to call the base class's <see cref="OnExit"/> method so that registered
/// delegates receive the event.
/// </remarks>
protected virtual void OnExit(StateEventArgs eventArgs)
{
var handler = Exit;
if (handler != null)
{
handler(this, eventArgs);
}
}
/// <summary>
/// Raises the <see cref="Action"/> event.
/// </summary>
/// <param name="eventArgs">
/// <see cref="StateEventArgs"/> object that provides the arguments for the event.
/// </param>
/// <remarks>
/// <strong>Notes to Inheritors:</strong> When overriding <see cref="OnAction"/> in a derived
/// class, be sure to call the base class's <see cref="OnAction"/> method so that registered
/// delegates receive the event.
/// </remarks>
internal protected virtual void OnAction(StateEventArgs eventArgs)
{
var handler = Action;
if (handler != null)
{
handler(this, eventArgs);
}
}
/// <summary>
/// Raises the <see cref="Update"/> event.
/// </summary>
/// <param name="eventArgs">
/// <see cref="StateEventArgs"/> object that provides the arguments for the event.
/// </param>
/// <remarks>
/// <strong>Notes to Inheritors:</strong> When overriding <see cref="OnUpdate"/> in a derived
/// class, be sure to call the base class's <see cref="OnUpdate"/> method so that registered
/// delegates receive the event.
/// </remarks>
protected virtual void OnUpdate(StateEventArgs eventArgs)
{
var handler = Update;
if (handler != null)
{
handler(this, eventArgs);
}
}
/// <summary>
/// Updates the active state.
/// </summary>
/// <param name="eventArgs">
/// The <see cref="StateEventArgs"/> instance containing the required data.
/// </param>
internal void UpdateState(StateEventArgs eventArgs)
{
if (Count == 0)
{
return; // Nothing to do.
}
Debug.Assert(ActiveState != null, "Cannot update state. Active state is not set.");
Debug.Assert(LastActiveState != null, "Last active state is not set.");
ActiveState.UpdateState(eventArgs);
}
/// <summary>
/// Performs state transitions.
/// </summary>
/// <param name="eventArgs">
/// The <see cref="StateEventArgs"/> instance containing the required data.
/// </param>
/// <returns>
/// The firing transition; or <see langword="null"/> if no transition is firing.
/// </returns>
internal Transition UpdateTransitions(StateEventArgs eventArgs)
{
if (ActiveState == null)
{
// No state active. --> Transition into a state.
// This happens at the first step of a state machine.
EnterState(null, eventArgs);
return(null);
}
// Check transitions of active state.
return(ActiveState.UpdateTransitions(eventArgs));
}
/// <summary>
/// Updates the state.
/// </summary>
/// <param name="eventArgs">
/// The <see cref="StateEventArgs"/> instance containing the required data.
/// </param>
internal void UpdateState(StateEventArgs eventArgs)
{
// Sub-states are updated first.
if (_parallelSubStates != null)
{
foreach (var stateCollection in _parallelSubStates)
{
stateCollection.UpdateState(eventArgs);
}
}
// Raise Update event.
OnUpdate(eventArgs);
}
/// <summary>
/// Exits to the specified target state.
/// </summary>
/// <param name="transition">The firing transition.</param>
/// <param name="eventArgs">
/// The <see cref="StateEventArgs"/> instance containing the required data.
/// </param>
internal void ExitState(Transition transition, StateEventArgs eventArgs)
{
if (Count == 0 || ActiveState == null)
{
return; // Nothing to do.
}
// Call exit on current state. The method will call true if the
// state was exited. If the ActiveState contains the target state,
// the method will return false and the ActiveState will still be active.
bool exited = ActiveState.ExitState(transition, eventArgs);
if (exited)
{
ActiveState = null;
}
}
/// <summary>
/// Enters the state.
/// </summary>
/// <param name="transition">The firing transition.</param>
/// <param name="eventArgs">
/// The <see cref="StateEventArgs"/> instance containing the required data.
/// </param>
internal void EnterState(Transition transition, StateEventArgs eventArgs)
{
if (!IsActive)
{
// State is not active. Raise Enter event.
OnEnter(eventArgs);
}
// Call Enter for sub-states.
if (_parallelSubStates != null)
{
foreach (var stateCollection in _parallelSubStates)
{
stateCollection.EnterState(transition, eventArgs);
}
}
}
/// <summary>
/// Exits to the specified target state.
/// </summary>
/// <param name="transition">The firing transition.</param>
/// <param name="eventArgs">
/// The <see cref="StateEventArgs"/> instance containing the required data.
/// </param>
/// <returns>
/// <see langword="true"/> if this state was exited. <see langword="false"/> if this state is
/// still active because the target state is a sub-state of this state.
/// </returns>
internal bool ExitState(Transition transition, StateEventArgs eventArgs)
{
Debug.Assert(IsActive, "Exit should only be called for active states.");
if (transition != null && !Transitions.Contains(transition) && Contains(transition.TargetState))
{
// The transition is not from this state and the target is a sub-state
// --> We do not leave the current state!
// We have to find the sub-state collection that contains the target. In this sub-state
// collection the active state will exit (and the target state will be entered later).
if (_parallelSubStates != null)
{
foreach (var stateCollection in _parallelSubStates)
{
if (stateCollection.ContainsRecursive(transition.TargetState))
{
stateCollection.ExitState(transition, eventArgs);
}
}
}
return(false);
// This approach assumes that there are no transitions from a state to a state in a
// parallel set. This is not explicitly forbidden (it is never verified in the state
// machine).
// Programmers must not create such transitions and graphical state machine editors
// should prohibit such constructs.
}
// The target state is no sub-state. --> Exit all sub-state collections.
if (_parallelSubStates != null)
{
foreach (var stateCollection in _parallelSubStates)
{
stateCollection.ExitState(null, eventArgs);
}
}
// Raise Exit event.
OnExit(eventArgs);
return(true);
}
/// <summary>
/// Enters a new state.
/// </summary>
/// <param name="transition">The transition. (Can be <see langword="null"/>.)</param>
/// <param name="eventArgs">
/// The <see cref="StateEventArgs"/> instance containing the required data.
/// </param>
internal void EnterState(Transition transition, StateEventArgs eventArgs)
{
if (Count == 0)
{
// Abort, nothing to do.
return;
}
// Current active state (can be null).
var newActiveState = ActiveState;
if (transition != null && ContainsRecursive(transition.TargetState))
{
// The target state is a state or sub-state.
// The new active state must be the state that contains the target state.
newActiveState = GetChild(transition.TargetState);
Debug.Assert(newActiveState != null, "New active state not found.");
}
if (newActiveState == null)
{
// We don't know which state to enter - enter history/initial state.
if (SaveHistory && LastActiveState != null)
{
newActiveState = LastActiveState;
}
else
{
newActiveState = InitialState;
}
}
// Enter the new state.
newActiveState.EnterState(transition, eventArgs);
// Now that state was entered we remember it as the active state.
ActiveState = newActiveState;
LastActiveState = newActiveState;
}
internal Transition UpdateTransitions(StateEventArgs eventArgs)
{
Transition firingTransition = null;
// Update sub-state transitions first.
if (_parallelSubStates != null)
{
foreach (var stateCollection in _parallelSubStates)
{
firingTransition = stateCollection.UpdateTransitions(eventArgs);
if (firingTransition != null && !stateCollection.ContainsRecursive(firingTransition.TargetState))
{
// The transition target is outside the sub-state collection.
// More parallel transition updates are only allowed for internal transitions.
break;
}
// There was no transition or the transition was an internal transition.
// We can check the next parallel state set.
}
}
// Abort if a transition was performed.
if (firingTransition != null)
{
return(firingTransition);
}
// Check transitions of this state.
foreach (var transition in Transitions)
{
if (transition.TargetState == null)
{
throw new InvalidOperationException("TargetState of transition must not be null.");
}
//if (transition.TargetState.StateMachine != StateMachine)
// throw new InvalidOperationException("TargetState of transition must not belong to different state machine.");
// Check transition.
bool fired = transition.Update(eventArgs.DeltaTime);
if (fired)
{
// Get state collection that contains this state and the target state.
var stateCollection = StateCollection.GetCollection(this, transition.TargetState);
// Exit states.
stateCollection.ExitState(transition, eventArgs);
// Execute transition action.
transition.OnAction(eventArgs);
// Enter states.
stateCollection.EnterState(transition, eventArgs);
// Do not update other transitions after first transition has fired.
return(transition);
}
}
return(null);
}
