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

1 files changed, 4 insertions, 11 deletions

diff --git a/src/corelib/statemachine/qabstracttransition.cpp b/src/corelib/statemachine/qabstracttransition.cpp
index 670aa7d..0004d3e 100644
--- a/src/corelib/statemachine/qabstracttransition.cpp
+++ b/src/corelib/statemachine/qabstracttransition.cpp
@@ -115,13 +115,10 @@ QAbstractTransitionPrivate *QAbstractTransitionPrivate::get(QAbstractTransition
 
 QStateMachine *QAbstractTransitionPrivate::machine() const
 {
-    QObject *par = parent;
-    while (par != 0) {
-        if (QStateMachine *mach = qobject_cast<QStateMachine*>(par))
-            return mach;
-        par = par->parent();
-    }
-    return 0;
+    QState *source = sourceState();
+    if (!source)
+        return 0;
+    return source->machine();
 }
 
 bool QAbstractTransitionPrivate::callEventTest(QEvent *e)
@@ -256,10 +253,6 @@ void QAbstractTransition::setTargetStates(const QList<QAbstractState*> &targets)
             qWarning("QAbstractTransition::setTargetStates: target state(s) cannot be null");
             return;
         }
-        if (target->machine() != 0 && target->machine()->rootState() == target) {
-            qWarning("QAbstractTransition::setTargetStates: root state cannot be target of transition");
-            return;
-        }
     }
 
     d->targetStates.clear();