Make QStateMachine inherit QState

This removes the need for a "root state" in the machine; or rather,
the machine _is_ the root state.
User code can now pass in a QStateMachine directly to the QState
constructor, instead of machine->rootState().
This also means we could get rid of the "proxying" from the machine
to the root state for things like properties (initialState et al),
finished() signal and auto-reparenting of states (the ChildAdded
event hack).
A fun little side-effect of this change is that it's now possible
to embed state machines within state machines. We can't think of
a good use case yet where you would rather embed a stand-alone
state machine (with its own event processing etc.) rather than
having just a regular nested state, but it's neat and it works.

Reviewed-by: Eskil Abrahamsen Blomfeldt

10 files changed, 29 insertions, 32 deletions

diff --git a/examples/animation/appchooser/main.cpp b/examples/animation/appchooser/main.cpp
index fe4be1fb86..97751b2725 100644
--- a/examples/animation/appchooser/main.cpp
+++ b/examples/animation/appchooser/main.cpp
@@ -134,7 +134,7 @@ int main(int argc, char **argv)
     QStateMachine machine;
     machine.setGlobalRestorePolicy(QStateMachine::RestoreProperties);
 
-    QState *group = new QState(machine.rootState());
+    QState *group = new QState(&machine);
     group->setObjectName("group");
     QRect selectedRect(86, 86, 128, 128);
 
diff --git a/examples/animation/moveblocks/main.cpp b/examples/animation/moveblocks/main.cpp
index c43e841016..97d3f81309 100644
--- a/examples/animation/moveblocks/main.cpp
+++ b/examples/animation/moveblocks/main.cpp
@@ -108,8 +108,7 @@ class StateSwitcher : public QState
     Q_OBJECT
 public:
     StateSwitcher(QStateMachine *machine)
-        : QState(machine->rootState()), m_machine(machine),
-          m_stateCount(0), m_lastIndex(0)
+        : QState(machine), m_stateCount(0), m_lastIndex(0)
     { }
 //![10]
 
@@ -120,7 +119,7 @@ public:
         while ((n = (qrand() % m_stateCount + 1)) == m_lastIndex)
         { }
         m_lastIndex = n;
-        m_machine->postEvent(new StateSwitchEvent(n));
+        machine()->postEvent(new StateSwitchEvent(n));
     }
     virtual void onExit(QEvent *) {}
 //![11]
@@ -135,7 +134,6 @@ public:
 //![12]
 
 private:
-    QStateMachine *m_machine;
     int m_stateCount;
     int m_lastIndex;
 };
diff --git a/examples/animation/states/main.cpp b/examples/animation/states/main.cpp
index b3c28f2492..99e04c3608 100644
--- a/examples/animation/states/main.cpp
+++ b/examples/animation/states/main.cpp
@@ -124,10 +124,9 @@ int main(int argc, char *argv[])
     scene.addItem(p6);
 
     QStateMachine machine;
-    QState *root = machine.rootState();
-    QState *state1 = new QState(root);
-    QState *state2 = new QState(root);
-    QState *state3 = new QState(root);
+    QState *state1 = new QState(&machine);
+    QState *state2 = new QState(&machine);
+    QState *state3 = new QState(&machine);
     machine.setInitialState(state1);
 
     // State 1
diff --git a/examples/animation/stickman/lifecycle.cpp b/examples/animation/stickman/lifecycle.cpp
index 2a54c826d4..c761d87a30 100644
--- a/examples/animation/stickman/lifecycle.cpp
+++ b/examples/animation/stickman/lifecycle.cpp
@@ -108,11 +108,11 @@ LifeCycle::LifeCycle(StickMan *stickMan, GraphicsView *keyReceiver)
     m_machine->addDefaultAnimation(m_animationGroup);
 //! [3]
 
-    m_alive = new QState(m_machine->rootState());
+    m_alive = new QState(m_machine);
     m_alive->setObjectName("alive");
     
     // Make it blink when lightning strikes before entering dead animation
-    QState *lightningBlink = new QState(m_machine->rootState());    
+    QState *lightningBlink = new QState(m_machine);    
     lightningBlink->assignProperty(m_stickMan->scene(), "backgroundBrush", Qt::white);
     lightningBlink->assignProperty(m_stickMan, "penColor", Qt::black);
     lightningBlink->assignProperty(m_stickMan, "fillColor", Qt::white);
@@ -126,7 +126,7 @@ LifeCycle::LifeCycle(StickMan *stickMan, GraphicsView *keyReceiver)
     QObject::connect(lightningBlink, SIGNAL(exited()), timer, SLOT(stop()));
 //! [5]
   
-    m_dead = new QState(m_machine->rootState());
+    m_dead = new QState(m_machine);
     m_dead->assignProperty(m_stickMan->scene(), "backgroundBrush", Qt::black);
     m_dead->assignProperty(m_stickMan, "penColor", Qt::white);
     m_dead->assignProperty(m_stickMan, "fillColor", Qt::black);
diff --git a/examples/animation/sub-attaq/boat.cpp b/examples/animation/sub-attaq/boat.cpp
index d286be5878..68e646e0b6 100644
--- a/examples/animation/sub-attaq/boat.cpp
+++ b/examples/animation/sub-attaq/boat.cpp
@@ -142,14 +142,14 @@ Boat::Boat(QGraphicsItem * parent, Qt::WindowFlags wFlags)
 
     //We setup the state machien of the boat
     machine = new QStateMachine(this);
-    QState *moving = new QState(machine->rootState());
+    QState *moving = new QState(machine);
     StopState *stopState = new StopState(this, moving);
     machine->setInitialState(moving);
     moving->setInitialState(stopState);
     MoveStateRight *moveStateRight = new MoveStateRight(this, moving);
     MoveStateLeft *moveStateLeft = new MoveStateLeft(this, moving);
-    LaunchStateRight *launchStateRight = new LaunchStateRight(this, machine->rootState());
-    LaunchStateLeft *launchStateLeft = new LaunchStateLeft(this, machine->rootState());
+    LaunchStateRight *launchStateRight = new LaunchStateRight(this, machine);
+    LaunchStateLeft *launchStateLeft = new LaunchStateLeft(this, machine);
 
     //then setup the transitions for the rightMove state
     KeyStopTransition *leftStopRight = new KeyStopTransition(this, QEvent::KeyPress, Qt::Key_Left);
@@ -216,10 +216,10 @@ Boat::Boat(QGraphicsItem * parent, Qt::WindowFlags wFlags)
     launchStateLeft->addTransition(historyState);
     launchStateRight->addTransition(historyState);
 
-    QFinalState *final = new QFinalState(machine->rootState());
+    QFinalState *final = new QFinalState(machine);
 
     //This state play the destroyed animation
-    QAnimationState *destroyedState = new QAnimationState(machine->rootState());
+    QAnimationState *destroyedState = new QAnimationState(machine);
     destroyedState->setAnimation(destroyAnimation);
 
     //Play a nice animation when the boat is destroyed
diff --git a/examples/animation/sub-attaq/bomb.cpp b/examples/animation/sub-attaq/bomb.cpp
index 454970a90d..e92a723307 100644
--- a/examples/animation/sub-attaq/bomb.cpp
+++ b/examples/animation/sub-attaq/bomb.cpp
@@ -85,11 +85,11 @@ void Bomb::launch(Bomb::Direction direction)
     QStateMachine *machine = new QStateMachine(this);
 
     //This state is when the launch animation is playing
-    QAnimationState *launched = new QAnimationState(machine->rootState());
+    QAnimationState *launched = new QAnimationState(machine);
     launched->setAnimation(launchAnimation);
 
     //End
-    QFinalState *final = new QFinalState(machine->rootState());
+    QFinalState *final = new QFinalState(machine);
 
     machine->setInitialState(launched);
 
diff --git a/examples/animation/sub-attaq/graphicsscene.cpp b/examples/animation/sub-attaq/graphicsscene.cpp
index bd37ce2f46..fcbc1b3921 100644
--- a/examples/animation/sub-attaq/graphicsscene.cpp
+++ b/examples/animation/sub-attaq/graphicsscene.cpp
@@ -230,17 +230,17 @@ void GraphicsScene::setupScene(const QList<QAction *> &actions)
     QStateMachine *machine = new QStateMachine(this);
 
     //This state is when the player is playing
-    PlayState *gameState = new PlayState(this,machine->rootState());
+    PlayState *gameState = new PlayState(this,machine);
 
     //Final state
-    QFinalState *final = new QFinalState(machine->rootState());
+    QFinalState *final = new QFinalState(machine);
 
     //Animation when the player enter in the game
-    QAnimationState *lettersMovingState = new QAnimationState(machine->rootState());
+    QAnimationState *lettersMovingState = new QAnimationState(machine);
     lettersMovingState->setAnimation(lettersGroupMoving);
 
     //Animation when the welcome screen disappear
-    QAnimationState *lettersFadingState = new QAnimationState(machine->rootState());
+    QAnimationState *lettersFadingState = new QAnimationState(machine);
     lettersFadingState->setAnimation(lettersGroupFading);
 
     //if new game then we fade out the welcome screen and start playing
diff --git a/examples/animation/sub-attaq/states.cpp b/examples/animation/sub-attaq/states.cpp
index 81fd2ded1c..d63737f52f 100644
--- a/examples/animation/sub-attaq/states.cpp
+++ b/examples/animation/sub-attaq/states.cpp
@@ -83,7 +83,7 @@ void PlayState::onEntry(QEvent *)
     machine = new QStateMachine(this);
 
     //This state is when player is playing
-    LevelState *levelState = new LevelState(scene, this, machine->rootState());
+    LevelState *levelState = new LevelState(scene, this, machine);
 
     //This state is when the player is actually playing but the game is not paused
     QState *playingState = new QState(levelState);
@@ -105,10 +105,10 @@ void PlayState::onEntry(QEvent *)
     pauseState->addTransition(pressPpause);
 
     //This state is when player have lost
-    LostState *lostState = new LostState(scene, this, machine->rootState());
+    LostState *lostState = new LostState(scene, this, machine);
 
     //This state is when player have won
-    WinState *winState = new WinState(scene, this, machine->rootState());
+    WinState *winState = new WinState(scene, this, machine);
 
     //The boat has been destroyed then the game is finished
     levelState->addTransition(scene->boat, SIGNAL(boatExecutionFinished()),lostState);
@@ -136,7 +136,7 @@ void PlayState::onEntry(QEvent *)
     machine->setInitialState(levelState);
 
     //Final state
-    QFinalState *final = new QFinalState(machine->rootState());
+    QFinalState *final = new QFinalState(machine);
 
     //This transition is triggered when the player press space after completing a level
     CustomSpaceTransition *spaceTransition = new CustomSpaceTransition(scene->views().at(0), this, QEvent::KeyPress, Qt::Key_Space);
diff --git a/examples/animation/sub-attaq/submarine.cpp b/examples/animation/sub-attaq/submarine.cpp
index 04b79169cd..78a9539896 100644
--- a/examples/animation/sub-attaq/submarine.cpp
+++ b/examples/animation/sub-attaq/submarine.cpp
@@ -115,7 +115,7 @@ SubMarine::SubMarine(int type, const QString &name, int points, QGraphicsItem *
     QStateMachine *machine = new QStateMachine(this);
 
     //This state is when the boat is moving/rotating
-    QState *moving = new QState(machine->rootState());
+    QState *moving = new QState(machine);
 
     //This state is when the boat is moving from left to right
     MovementState *movement = new MovementState(this, moving);
@@ -132,7 +132,7 @@ SubMarine::SubMarine(int type, const QString &name, int points, QGraphicsItem *
     machine->setInitialState(moving);
 
     //End
-    QFinalState *final = new QFinalState(machine->rootState());
+    QFinalState *final = new QFinalState(machine);
 
     //If the moving animation is finished we move to the return state
     movement->addTransition(movement, SIGNAL(animationFinished()), rotation);
@@ -141,7 +141,7 @@ SubMarine::SubMarine(int type, const QString &name, int points, QGraphicsItem *
     rotation->addTransition(rotation, SIGNAL(animationFinished()), movement);
 
     //This state play the destroyed animation
-    QAnimationState *destroyedState = new QAnimationState(machine->rootState());
+    QAnimationState *destroyedState = new QAnimationState(machine);
     destroyedState->setAnimation(setupDestroyAnimation(this));
 
     //Play a nice animation when the submarine is destroyed
diff --git a/examples/animation/sub-attaq/torpedo.cpp b/examples/animation/sub-attaq/torpedo.cpp
index 5ef237a32d..fe79488c54 100644
--- a/examples/animation/sub-attaq/torpedo.cpp
+++ b/examples/animation/sub-attaq/torpedo.cpp
@@ -74,11 +74,11 @@ void Torpedo::launch()
     QStateMachine *machine = new QStateMachine(this);
 
     //This state is when the launch animation is playing
-    QAnimationState *launched = new QAnimationState(machine->rootState());
+    QAnimationState *launched = new QAnimationState(machine);
     launched->setAnimation(launchAnimation);
 
     //End
-    QFinalState *final = new QFinalState(machine->rootState());
+    QFinalState *final = new QFinalState(machine);
 
     machine->setInitialState(launched);