path: root/src/corelib/statemachine/qstatemachine.cpp

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#include "qstatemachine.h"

#ifndef QT_NO_STATEMACHINE

#include "qstate.h"
#include "qstate_p.h"
#include "qstatemachine_p.h"
#include "qabstracttransition.h"
#include "qabstracttransition_p.h"
#include "qsignaltransition.h"
#include "qsignaltransition_p.h"
#include "qsignalevent.h"
#include "qsignaleventgenerator_p.h"
#include "qabstractstate.h"
#include "qabstractstate_p.h"
#include "qfinalstate.h"
#include "qhistorystate.h"
#include "qhistorystate_p.h"
#include "private/qobject_p.h"
#include "private/qthread_p.h"

#ifndef QT_NO_STATEMACHINE_EVENTFILTER
#include "qeventtransition.h"
#include "qeventtransition_p.h"
#include "qwrappedevent.h"
#endif

#ifndef QT_NO_ANIMATION
#include "qpropertyanimation.h"
#include "qanimationgroup.h"
#include <private/qvariantanimation_p.h>
#endif

#include <QtCore/qmetaobject.h>
#include <qdebug.h>

QT_BEGIN_NAMESPACE

/*!
  \class QStateMachine
  \reentrant

  \brief The QStateMachine class provides a hierarchical finite state machine.

  \since 4.6
  \ingroup statemachine

    QStateMachine is based on the concepts and notation of
    \l{Statecharts: A visual formalism for complex
    systems}{Statecharts}. QStateMachine is part of \l{The State
    Machine Framework}.

    A state machine manages a set of states (classes that inherit from
    QAbstractState) and transitions (descendants of
    QAbstractTransition) between those states; these states and
    transitions define a state graph. Once a state graph has been
    built, the state machine can execute it. QStateMachine's
    execution algorithm is based on the \l{State Chart XML: State
    Machine Notation for Control Abstraction}{State Chart XML (SCXML)}
    algorithm. The framework's \l{The State Machine
    Framework}{overview} gives several state graphs and the code to
    build them.

    The rootState() is the parent of all top-level states in the
    machine; it is used, for instance, when the state graph is
    deleted. It is created by the machine.

    Use the addState() function to add a state to the state machine.
    All top-level states are added to the root state. States are
    removed with the removeState() function. Removing states while the
    machine is running is discouraged.

    Before the machine can be started, the \l{initialState}{initial
    state} must be set. The initial state is the state that the
    machine enters when started. You can then start() the state
    machine. The started() signal is emitted when the initial state is
    entered.

    The machine is event driven and keeps its own event loop. Events
    are posted to the machine through postEvent(). Note that this
    means that it executes asynchronously, and that it will not
    progress without a running event loop. You will normally not have
    to post events to the machine directly as Qt's transitions, e.g.,
    QEventTransition and its subclasses, handle this. But for custom
    transitions triggered by events, postEvent() is useful.

    The state machine processes events and takes transitions until a
    top-level final state is entered; the state machine then emits the
    finished() signal. You can also stop() the state machine
    explicitly. The stopped() signal is emitted in this case.

    The following snippet shows a state machine that will finish when a button
    is clicked:

    \code
    QPushButton button;

    QStateMachine machine;
    QState *s1 = new QState();
    s1->assignProperty(&button, "text", "Click me");

    QFinalState *s2 = new QFinalState();
    s1->addTransition(&button, SIGNAL(clicked()), s2);

    machine.addState(s1);
    machine.addState(s2);
    machine.setInitialState(s1);
    machine.start();
    \endcode

    This code example uses QState, which inherits QAbstractState. The
    QState class provides a state that you can use to set properties
    and invoke methods on \l{QObject}s when the state is entered or
    exited. It also contains convenience functions for adding
    transitions, e.g., \l{QSignalTransition}s as in this example. See
    the QState class description for further details.

    If an error is encountered, the machine will enter the
    \l{errorState}{error state}, which is a special state created by
    the machine. The types of errors possible are described by the
    \l{QStateMachine::}{Error} enum. After the error state is entered,
    the type of the error can be retrieved with error(). The execution
    of the state graph will not stop when the error state is entered.
    So it is possible to handle the error, for instance, by connecting
    to the \l{QAbstractState::}{entered()} signal of the error state.
    It is also possible to set a custom error state with
    setErrorState().

    \omit This stuff will be moved elsewhere
This is
  typically used in conjunction with \l{Signals and Slots}{signals}; the
  signals determine the flow of the state graph, whereas the states' property
  assignments and method invocations are the actions.

  The postEvent() function posts an event to the state machine. This is useful
  when you are using custom events to trigger transitions.
    \endomit

  \sa QAbstractState, QAbstractTransition, QState, {The State Machine Framework}
*/

/*!
    \property QStateMachine::rootState

    \brief the root state of this state machine
*/

/*!
    \property QStateMachine::initialState

    \brief the initial state of this state machine

    The initial state must be one of the rootState()'s child states.
*/

/*!
    \property QStateMachine::errorState

    \brief the error state of this state machine
*/

/*!
    \property QStateMachine::errorString

    \brief the error string of this state machine
*/

/*!
    \property QStateMachine::globalRestorePolicy

    \brief the restore policy for states of this state machine.

    The default value of this property is
    QStateMachine::DoNotRestoreProperties.
*/

#ifndef QT_NO_ANIMATION
/*!
    \property QStateMachine::animationsEnabled

    \brief whether animations are enabled

    The default value of this property is true.

    \sa QAbstractTransition::addAnimation()
*/
#endif

// #define QSTATEMACHINE_DEBUG

QStateMachinePrivate::QStateMachinePrivate()
{
    state = NotRunning;
    processing = false;
    processingScheduled = false;
    stop = false;
    error = QStateMachine::NoError;
    globalRestorePolicy = QStateMachine::DoNotRestoreProperties;
    rootState = 0;
    initialErrorStateForRoot = 0;
    signalEventGenerator = 0;
#ifndef QT_NO_ANIMATION
    animationsEnabled = true;
#endif
}

QStateMachinePrivate::~QStateMachinePrivate()
{
    qDeleteAll(internalEventQueue);
    qDeleteAll(externalEventQueue);
}

QStateMachinePrivate *QStateMachinePrivate::get(QStateMachine *q)
{
    if (q)
        return q->d_func();
    return 0;
}

static QEvent *cloneEvent(QEvent *e)
{
    switch (e->type()) {
    case QEvent::None:
        return new QEvent(*e);
    case QEvent::Timer:
        return new QTimerEvent(*static_cast<QTimerEvent*>(e));
    default:
        Q_ASSERT_X(false, "cloneEvent()", "not implemented");
        break;
    }
    return 0;
}

const QStateMachinePrivate::Handler qt_kernel_statemachine_handler = {
    cloneEvent
};

const QStateMachinePrivate::Handler *QStateMachinePrivate::handler = &qt_kernel_statemachine_handler;

Q_CORE_EXPORT const QStateMachinePrivate::Handler *qcoreStateMachineHandler()
{
    return &qt_kernel_statemachine_handler;
}

static int indexOfDescendant(QState *s, QAbstractState *desc)
{
    QList<QAbstractState*> childStates = QStatePrivate::get(s)->childStates();
    for (int i = 0; i < childStates.size(); ++i) {
        QAbstractState *c = childStates.at(i);
        if ((c == desc) || QStateMachinePrivate::isDescendantOf(desc, c)) {
            return i;
        }
    }
    return -1;
}

bool QStateMachinePrivate::stateEntryLessThan(QAbstractState *s1, QAbstractState *s2)
{
    if (s1->parent() == s2->parent()) {
        return s1->children().indexOf(s1)
            < s2->children().indexOf(s2);
    } else if (isDescendantOf(s1, s2)) {
        return false;
    } else if (isDescendantOf(s2, s1)) {
        return true;
    } else {
        QState *lca = findLCA(QList<QAbstractState*>() << s1 << s2);
        Q_ASSERT(lca != 0);
        return (indexOfDescendant(lca, s1) < indexOfDescendant(lca, s2));
    }
}

bool QStateMachinePrivate::stateExitLessThan(QAbstractState *s1, QAbstractState *s2)
{
    if (s1->parent() == s2->parent()) {
        return s1->children().indexOf(s1)
            < s2->children().indexOf(s2);
    } else if (isDescendantOf(s1, s2)) {
        return true;
    } else if (isDescendantOf(s2, s1)) {
        return false;
    } else {
        QState *lca = findLCA(QList<QAbstractState*>() << s1 << s2);
        Q_ASSERT(lca != 0);
        return (indexOfDescendant(lca, s1) < indexOfDescendant(lca, s2));
    }
}

QState *QStateMachinePrivate::findLCA(const QList<QAbstractState*> &states)
{
    if (states.isEmpty())
        return 0;
    QList<QState*> ancestors = properAncestors(states.at(0), 0);
    for (int i = 0; i < ancestors.size(); ++i) {
        QState *anc = ancestors.at(i);
        bool ok = true;
        for (int j = states.size() - 1; (j > 0) && ok; --j) {
            const QAbstractState *s = states.at(j);
            if (!isDescendantOf(s, anc))
                ok = false;
        }
        if (ok)
            return anc;
    }
    return 0;
}

bool QStateMachinePrivate::isPreempted(const QAbstractState *s, const QSet<QAbstractTransition*> &transitions) const
{
    QSet<QAbstractTransition*>::const_iterator it;
    for (it = transitions.constBegin(); it != transitions.constEnd(); ++it) {
        QAbstractTransition *t = *it;
        QList<QAbstractState*> lst = t->targetStates();
        if (!lst.isEmpty()) {
            lst.prepend(t->sourceState());
            QAbstractState *lca = findLCA(lst);
            if (isDescendantOf(s, lca)) {
#ifdef QSTATEMACHINE_DEBUG
                qDebug() << q_func() << ':' << transitions << "preempts selection of a transition from"
                         << s << "because" << s << "is a descendant of" << lca;
#endif
                return true;
            }
        }
    }
    return false;
}

QSet<QAbstractTransition*> QStateMachinePrivate::selectTransitions(QEvent *event) const
{
    Q_Q(const QStateMachine);
    QSet<QAbstractTransition*> enabledTransitions;
    QSet<QAbstractState*>::const_iterator it;
    const_cast<QStateMachine*>(q)->beginSelectTransitions(event);
    for (it = configuration.constBegin(); it != configuration.constEnd(); ++it) {
        QAbstractState *state = *it;
        if (!isAtomic(state))
            continue;
        if (isPreempted(state, enabledTransitions))
            continue;
        QList<QState*> lst = properAncestors(state, 0);
        if (QState *grp = qobject_cast<QState*>(state))
            lst.prepend(grp);
        bool found = false;
        for (int j = 0; (j < lst.size()) && !found; ++j) {
            QState *s = lst.at(j);
            QList<QAbstractTransition*> transitions = QStatePrivate::get(s)->transitions();
            for (int k = 0; k < transitions.size(); ++k) {
                QAbstractTransition *t = transitions.at(k);
                if (QAbstractTransitionPrivate::get(t)->callEventTest(event)) {
#ifdef QSTATEMACHINE_DEBUG
                    qDebug() << q << ": selecting transition" << t;
#endif
                    enabledTransitions.insert(t);
                    found = true;
                    break;
                }
            }
        }
    }
    const_cast<QStateMachine*>(q)->endSelectTransitions(event);
    return enabledTransitions;
}

void QStateMachinePrivate::microstep(QEvent *event, const QList<QAbstractTransition*> &enabledTransitions)
{
#ifdef QSTATEMACHINE_DEBUG
    qDebug() << q_func() << ": begin microstep( enabledTransitions:" << enabledTransitions << ')';
    qDebug() << q_func() << ": configuration before exiting states:" << configuration;
#endif
    QList<QAbstractState*> exitedStates = exitStates(event, enabledTransitions);
#ifdef QSTATEMACHINE_DEBUG
    qDebug() << q_func() << ": configuration after exiting states:" << configuration;
#endif
    executeTransitionContent(event, enabledTransitions);
    QList<QAbstractState*> enteredStates = enterStates(event, enabledTransitions);
    applyProperties(enabledTransitions, exitedStates, enteredStates);
#ifdef QSTATEMACHINE_DEBUG
    qDebug() << q_func() << ": configuration after entering states:" << configuration;
    qDebug() << q_func() << ": end microstep";
#endif
}

QList<QAbstractState*> QStateMachinePrivate::exitStates(QEvent *event, const QList<QAbstractTransition*> &enabledTransitions)
{
//    qDebug() << "exitStates(" << enabledTransitions << ')';
    QSet<QAbstractState*> statesToExit;
//    QSet<QAbstractState*> statesToSnapshot;
    for (int i = 0; i < enabledTransitions.size(); ++i) {
        QAbstractTransition *t = enabledTransitions.at(i);
        QList<QAbstractState*> lst = t->targetStates();
        if (lst.isEmpty())
            continue;
        lst.prepend(t->sourceState());
        QAbstractState *lca = findLCA(lst);
        if (lca == 0) {
            setError(QStateMachine::NoCommonAncestorForTransitionError, t->sourceState());
            lst = pendingErrorStates.toList();
            lst.prepend(t->sourceState());
            
            lca = findLCA(lst);
            Q_ASSERT(lca != 0);
        }

        {
            QSet<QAbstractState*>::const_iterator it;
            for (it = configuration.constBegin(); it != configuration.constEnd(); ++it) {
                QAbstractState *s = *it;
                if (isDescendantOf(s, lca))
                    statesToExit.insert(s);
            }
        }
    }
    QList<QAbstractState*> statesToExit_sorted = statesToExit.toList();
    qSort(statesToExit_sorted.begin(), statesToExit_sorted.end(), stateExitLessThan);
    for (int i = 0; i < statesToExit_sorted.size(); ++i) {
        QAbstractState *s = statesToExit_sorted.at(i);
        if (QState *grp = qobject_cast<QState*>(s)) {
            QList<QHistoryState*> hlst = QStatePrivate::get(grp)->historyStates();
            for (int j = 0; j < hlst.size(); ++j) {
                QHistoryState *h = hlst.at(j);
                QHistoryStatePrivate::get(h)->configuration.clear();
                QSet<QAbstractState*>::const_iterator it;
                for (it = configuration.constBegin(); it != configuration.constEnd(); ++it) {
                    QAbstractState *s0 = *it;
                    if (QHistoryStatePrivate::get(h)->historyType == QHistoryState::DeepHistory) {
                        if (isAtomic(s0) && isDescendantOf(s0, s))
                            QHistoryStatePrivate::get(h)->configuration.append(s0);
                    } else if (s0->parentState() == s) {
                        QHistoryStatePrivate::get(h)->configuration.append(s0);
                    }
                }
#ifdef QSTATEMACHINE_DEBUG
                qDebug() << q_func() << ": recorded" << ((QHistoryStatePrivate::get(h)->historyType == QHistoryState::DeepHistory) ? "deep" : "shallow")
                         << "history for" << s << "in" << h << ':' << QHistoryStatePrivate::get(h)->configuration;
#endif
            }
        }
    }
    for (int i = 0; i < statesToExit_sorted.size(); ++i) {
        QAbstractState *s = statesToExit_sorted.at(i);
#ifdef QSTATEMACHINE_DEBUG
        qDebug() << q_func() << ": exiting" << s;
#endif
        QAbstractStatePrivate::get(s)->callOnExit(event);
        configuration.remove(s);
        QAbstractStatePrivate::get(s)->emitExited();
    }
    return statesToExit_sorted;
}

void QStateMachinePrivate::executeTransitionContent(QEvent *event, const QList<QAbstractTransition*> &enabledTransitions)
{
    for (int i = 0; i < enabledTransitions.size(); ++i) {
        QAbstractTransition *t = enabledTransitions.at(i);
#ifdef QSTATEMACHINE_DEBUG
        qDebug() << q_func() << ": triggering" << t;
#endif
        QAbstractTransitionPrivate::get(t)->callOnTransition(event);
        QAbstractTransitionPrivate::get(t)->emitTriggered();
    }
}

QList<QAbstractState*> QStateMachinePrivate::enterStates(QEvent *event, const QList<QAbstractTransition*> &enabledTransitions)
{
#ifdef QSTATEMACHINE_DEBUG
    Q_Q(QStateMachine);
#endif
//    qDebug() << "enterStates(" << enabledTransitions << ')';
    QSet<QAbstractState*> statesToEnter;
    QSet<QAbstractState*> statesForDefaultEntry;

    if (pendingErrorStates.isEmpty()) {
        for (int i = 0; i < enabledTransitions.size(); ++i) {
            QAbstractTransition *t = enabledTransitions.at(i);
            QList<QAbstractState*> lst = t->targetStates();
            if (lst.isEmpty())
                continue;
            lst.prepend(t->sourceState());
            QState *lca = findLCA(lst);
            for (int j = 1; j < lst.size(); ++j) {
                QAbstractState *s = lst.at(j);
			    addStatesToEnter(s, lca, statesToEnter, statesForDefaultEntry);
                if (isParallel(lca)) {
                    QList<QAbstractState*> lcac = QStatePrivate::get(lca)->childStates();
                    foreach (QAbstractState* child,lcac) {
                        if (!statesToEnter.contains(child))
                            addStatesToEnter(child,lca,statesToEnter,statesForDefaultEntry);                    
                    }
                }
            }
        }
    }

    // Did an error occur while selecting transitions? Then we enter the error state.
    if (!pendingErrorStates.isEmpty()) {
        statesToEnter.clear();
        statesToEnter = pendingErrorStates;
        statesForDefaultEntry = pendingErrorStatesForDefaultEntry;
        pendingErrorStates.clear();
        pendingErrorStatesForDefaultEntry.clear();
    }

    QList<QAbstractState*> statesToEnter_sorted = statesToEnter.toList();
    qSort(statesToEnter_sorted.begin(), statesToEnter_sorted.end(), stateEntryLessThan);

    for (int i = 0; i < statesToEnter_sorted.size(); ++i) {
        QAbstractState *s = statesToEnter_sorted.at(i);
#ifdef QSTATEMACHINE_DEBUG
        qDebug() << q << ": entering" << s;
#endif
        configuration.insert(s);
        registerTransitions(s);
        QAbstractStatePrivate::get(s)->callOnEntry(event);
        QAbstractStatePrivate::get(s)->emitEntered();
        if (statesForDefaultEntry.contains(s)) {
            // ### executeContent(s.initial.transition.children())
        }
        if (isFinal(s)) {
            QState *parent = s->parentState();
            if (parent) {
                QState *grandparent = parent->parentState();
#ifdef QSTATEMACHINE_DEBUG
                qDebug() << q << ": emitting finished signal for" << parent;
#endif
                QStatePrivate::get(parent)->emitFinished();
                if (grandparent && isParallel(grandparent)) {
                    bool allChildStatesFinal = true;
                    QList<QAbstractState*> childStates = QStatePrivate::get(grandparent)->childStates();
                    for (int j = 0; j < childStates.size(); ++j) {
                        QAbstractState *cs = childStates.at(j);
                        if (!isInFinalState(cs)) {
                            allChildStatesFinal = false;
                            break;
                        }
                    }
                    if (allChildStatesFinal) {
#ifdef QSTATEMACHINE_DEBUG
                        qDebug() << q << ": emitting finished signal for" << grandparent;
#endif
                        QStatePrivate::get(grandparent)->emitFinished();
                    }
                }
            }
        }
    }
    {
        QSet<QAbstractState*>::const_iterator it;
        for (it = configuration.constBegin(); it != configuration.constEnd(); ++it) {
            if (isFinal(*it) && (*it)->parentState() == rootState) {
                processing = false;
                stopProcessingReason = Finished;
                break;
            }
        }
    }
//    qDebug() << "configuration:" << configuration.toList();
    return statesToEnter_sorted;
}

void QStateMachinePrivate::addStatesToEnter(QAbstractState *s, QState *root,
                                            QSet<QAbstractState*> &statesToEnter,
                                            QSet<QAbstractState*> &statesForDefaultEntry)
{
	if (QHistoryState *h = qobject_cast<QHistoryState*>(s)) {
		QList<QAbstractState*> hconf = QHistoryStatePrivate::get(h)->configuration;
		if (!hconf.isEmpty()) {
			for (int k = 0; k < hconf.size(); ++k) {
				QAbstractState *s0 = hconf.at(k);
				addStatesToEnter(s0, root, statesToEnter, statesForDefaultEntry);
			}
	#ifdef QSTATEMACHINE_DEBUG
			qDebug() <<q_func() << ": restoring"
					<< ((QHistoryStatePrivate::get(h)->historyType == QHistoryState::DeepHistory) ? "deep" : "shallow")
					<< "history from" << s << ':' << hconf;
	#endif
		} else {
			QList<QAbstractState*> hlst;
			if (QHistoryStatePrivate::get(h)->defaultState)
				hlst.append(QHistoryStatePrivate::get(h)->defaultState);

			if (hlst.isEmpty()) {
				setError(QStateMachine::NoDefaultStateInHistoryStateError, h);
			} else {
				for (int k = 0; k < hlst.size(); ++k) {
					QAbstractState *s0 = hlst.at(k);
					addStatesToEnter(s0, root, statesToEnter, statesForDefaultEntry);
				}
	#ifdef QSTATEMACHINE_DEBUG
				qDebug() << q_func() << ": initial history targets for" << s << ':' << hlst;
	#endif
			}
		}
	} else {
		statesToEnter.insert(s);
		if (isParallel(s)) {
			QState *grp = qobject_cast<QState*>(s);
			QList<QAbstractState*> lst = QStatePrivate::get(grp)->childStates();
			for (int i = 0; i < lst.size(); ++i) {
				QAbstractState *child = lst.at(i);
				addStatesToEnter(child, grp, statesToEnter, statesForDefaultEntry);
			}
		} else if (isCompound(s)) {
			statesForDefaultEntry.insert(s);
			QState *grp = qobject_cast<QState*>(s);
			QAbstractState *initial = grp->initialState();
			if (initial != 0) {
				addStatesToEnter(initial, grp, statesToEnter, statesForDefaultEntry);
			} else {
				setError(QStateMachine::NoInitialStateError, grp);
				return;
			}
		}
		QList<QState*> ancs = properAncestors(s, root);
		for (int i = 0; i < ancs.size(); ++i) {
			QState *anc = ancs.at(i);
			if (!anc->parentState())
				continue;
			statesToEnter.insert(anc);
			if (isParallel(anc)) {
				QList<QAbstractState*> lst = QStatePrivate::get(anc)->childStates();
				for (int j = 0; j < lst.size(); ++j) {
					QAbstractState *child = lst.at(j);
					bool hasDescendantInList = false;
					QSet<QAbstractState*>::const_iterator it;
					for (it = statesToEnter.constBegin(); it != statesToEnter.constEnd(); ++it) {
						if (isDescendantOf(*it, child)) {
							hasDescendantInList = true;
							break;
						}
					}
					if (!hasDescendantInList)
						addStatesToEnter(child, anc, statesToEnter, statesForDefaultEntry);
				}
			}
		}
	}
}

void QStateMachinePrivate::applyProperties(const QList<QAbstractTransition*> &transitionList,
                                           const QList<QAbstractState*> &exitedStates,
                                           const QList<QAbstractState*> &enteredStates)
{
#ifdef QT_NO_ANIMATION
    Q_UNUSED(transitionList);
    Q_UNUSED(exitedStates);
#else
    Q_Q(QStateMachine);
#endif
    // Process the property assignments of the entered states.
    QHash<QAbstractState*, QList<QPropertyAssignment> > propertyAssignmentsForState;
    QHash<RestorableId, QVariant> pendingRestorables = registeredRestorables;
    for (int i = 0; i < enteredStates.size(); ++i) {
        QState *s = qobject_cast<QState*>(enteredStates.at(i));
        if (!s)
            continue;

        QList<QPropertyAssignment> assignments = QStatePrivate::get(s)->propertyAssignments;
        for (int j = 0; j < assignments.size(); ++j) {
            const QPropertyAssignment &assn = assignments.at(j);
            if (globalRestorePolicy == QStateMachine::RestoreProperties) {
                registerRestorable(assn.object, assn.propertyName);
            }
            pendingRestorables.remove(RestorableId(assn.object, assn.propertyName));
            propertyAssignmentsForState[s].append(assn);
        }

        // Remove pending restorables for all parent states to avoid restoring properties
        // before the state that assigned them is exited. If state does not explicitly 
        // assign a property which is assigned by the parent, it inherits the parent's assignment.
        QState *parentState = s;
        while ((parentState = parentState->parentState()) != 0) {
            assignments = QStatePrivate::get(parentState)->propertyAssignments;
            for (int j=0; j<assignments.size(); ++j) {
                const QPropertyAssignment &assn = assignments.at(j);
                int c = pendingRestorables.remove(RestorableId(assn.object, assn.propertyName));
                if (c > 0)
                    propertyAssignmentsForState[s].append(assn);                
            }
        }
    }
    if (!pendingRestorables.isEmpty()) {
        QAbstractState *s;
        if (!enteredStates.isEmpty())
            s = enteredStates.last(); // ### handle if parallel
        else
            s = 0;
        propertyAssignmentsForState[s] << restorablesToPropertyList(pendingRestorables);
    }

#ifndef QT_NO_ANIMATION
    // Gracefully terminate playing animations for states that are exited.
    for (int i = 0; i < exitedStates.size(); ++i) {
        QAbstractState *s = exitedStates.at(i);
        QList<QAbstractAnimation*> animations = animationsForState.take(s);
        for (int j = 0; j < animations.size(); ++j) {
            QAbstractAnimation *anim = animations.at(j);
            QObject::disconnect(anim, SIGNAL(finished()), q, SLOT(_q_animationFinished()));
            stateForAnimation.remove(anim);

            // Stop the (top-level) animation.
            // ### Stopping nested animation has weird behavior.
            QAbstractAnimation *topLevelAnim = anim;
            while (QAnimationGroup *group = topLevelAnim->group())
                topLevelAnim = group;
            topLevelAnim->stop();

            if (resetAnimationEndValues.contains(anim)) {
                qobject_cast<QVariantAnimation*>(anim)->setEndValue(QVariant()); // ### generalize
                resetAnimationEndValues.remove(anim);
            }
            QPropertyAssignment assn = propertyForAnimation.take(anim);
            Q_ASSERT(assn.object != 0);
            // If there is no property assignment that sets this property,
            // set the property to its target value.
            bool found = false;
            QHash<QAbstractState*, QList<QPropertyAssignment> >::const_iterator it;
            for (it = propertyAssignmentsForState.constBegin(); it != propertyAssignmentsForState.constEnd(); ++it) {
                const QList<QPropertyAssignment> &assignments = it.value();
                for (int k = 0; k < assignments.size(); ++k) {
                    if ((assignments.at(k).object == assn.object)
                        && (assignments.at(k).propertyName == assn.propertyName)) {
                        found = true;
                        break;
                    }
                }
            }
            if (!found) {
                assn.object->setProperty(assn.propertyName, assn.value);
            }
        }
    }

    // Find the animations to use for the state change.
    QList<QAbstractAnimation*> selectedAnimations;
    if (animationsEnabled) {
        for (int i = 0; i < transitionList.size(); ++i) {
            QAbstractTransition *transition = transitionList.at(i);

            selectedAnimations << transition->animations();
            selectedAnimations << defaultAnimationsForSource.values(transition->sourceState());

            QList<QAbstractState *> targetStates = transition->targetStates();
            for (int j=0; j<targetStates.size(); ++j) 
                selectedAnimations << defaultAnimationsForTarget.values(targetStates.at(j));
        }
        selectedAnimations << defaultAnimations;
    }

    // Initialize animations from property assignments.
    for (int i = 0; i < selectedAnimations.size(); ++i) {
        QAbstractAnimation *anim = selectedAnimations.at(i);
        QHash<QAbstractState*, QList<QPropertyAssignment> >::iterator it;
        for (it = propertyAssignmentsForState.begin(); it != propertyAssignmentsForState.end(); ) {
            QList<QPropertyAssignment>::iterator it2;
            QAbstractState *s = it.key();
            QList<QPropertyAssignment> &assignments = it.value();
            for (it2 = assignments.begin(); it2 != assignments.end(); ) {
                QPair<QList<QAbstractAnimation*>, QList<QAbstractAnimation*> > ret;
                ret = initializeAnimation(anim, *it2);
                QList<QAbstractAnimation*> handlers = ret.first;
                if (!handlers.isEmpty()) {
                    for (int j = 0; j < handlers.size(); ++j) {
                        QAbstractAnimation *a = handlers.at(j);
                        propertyForAnimation.insert(a, *it2);
                        stateForAnimation.insert(a, s);
                        animationsForState[s].append(a);
                        // ### connect to just the top-level animation?
                        QObject::connect(a, SIGNAL(finished()), q, SLOT(_q_animationFinished()), Qt::UniqueConnection);
                    }
                    it2 = assignments.erase(it2);
                } else {
                    ++it2;
                }
                for (int j = 0; j < ret.second.size(); ++j)
                    resetAnimationEndValues.insert(ret.second.at(j));
            }
            if (assignments.isEmpty())
                it = propertyAssignmentsForState.erase(it);
            else
                ++it;
        }
        // We require that at least one animation is valid.
        // ### generalize
        QList<QVariantAnimation*> variantAnims = qFindChildren<QVariantAnimation*>(anim);
        if (QVariantAnimation *va = qobject_cast<QVariantAnimation*>(anim))
            variantAnims.append(va);
        
        bool hasValidEndValue = false;
        for (int j = 0; j < variantAnims.size(); ++j) {
            if (variantAnims.at(j)->endValue().isValid()) {
                hasValidEndValue = true;
                break;
            }
        }

        if (hasValidEndValue) {
            anim->start();
        }
    }
#endif // !QT_NO_ANIMATION

    // Immediately set the properties that are not animated.
    {
        QHash<QAbstractState*, QList<QPropertyAssignment> >::const_iterator it;
        for (it = propertyAssignmentsForState.constBegin(); it != propertyAssignmentsForState.constEnd(); ++it) {
            const QList<QPropertyAssignment> &assignments = it.value();
            for (int i = 0; i < assignments.size(); ++i) {
                const QPropertyAssignment &assn = assignments.at(i);
                assn.object->setProperty(assn.propertyName, assn.value);
            }
        }
    }

    // Emit polished signal for entered states that have no animated properties.
    for (int i = 0; i < enteredStates.size(); ++i) {
        QState *s = qobject_cast<QState*>(enteredStates.at(i));
        if (s 
#ifndef QT_NO_ANIMATION
            && !animationsForState.contains(s)
#endif
            )
            QStatePrivate::get(s)->emitPolished();
    }
}

bool QStateMachinePrivate::isFinal(const QAbstractState *s)
{
    return qobject_cast<const QFinalState*>(s) != 0;
}

bool QStateMachinePrivate::isParallel(const QAbstractState *s)
{
    const QState *ss = qobject_cast<const QState*>(s);
    return ss && (QStatePrivate::get(ss)->childMode == QState::ParallelStates);
}

bool QStateMachinePrivate::isCompound(const QAbstractState *s)
{
    const QState *group = qobject_cast<const QState*>(s);
    if (!group)
        return false;
    return (!isParallel(group) && !QStatePrivate::get(group)->childStates().isEmpty())
        || (qobject_cast<QStateMachine*>(group->parent()) != 0);
}

bool QStateMachinePrivate::isAtomic(const QAbstractState *s)
{
    const QState *ss = qobject_cast<const QState*>(s);
    return (ss && QStatePrivate::get(ss)->childStates().isEmpty())
         || isFinal(s);
}


bool QStateMachinePrivate::isDescendantOf(const QAbstractState *state, const QAbstractState *other)
{
    Q_ASSERT(state != 0);
    for (QAbstractState *s = state->parentState(); s != 0; s = s->parentState()) {
        if (s == other)
            return true;
    }
    return false;
}

QList<QState*> QStateMachinePrivate::properAncestors(const QAbstractState *state, const QState *upperBound)
{
    Q_ASSERT(state != 0);
    QList<QState*> result;
    for (QState *s = state->parentState(); s && s != upperBound; s = s->parentState()) {
        result.append(s);
    }
    return result;
}

bool QStateMachinePrivate::isInFinalState(QAbstractState* s) const
{
    if (isCompound(s)) {
        QState *grp = qobject_cast<QState*>(s);
        QList<QAbstractState*> lst = QStatePrivate::get(grp)->childStates();
        for (int i = 0; i < lst.size(); ++i) {
            QAbstractState *cs = lst.at(i);
            if (isFinal(cs) && configuration.contains(cs))
                return true;
        }
        return false;
    } else if (isParallel(s)) {
        QState *grp = qobject_cast<QState*>(s);
        QList<QAbstractState*> lst = QStatePrivate::get(grp)->childStates();
        for (int i = 0; i < lst.size(); ++i) {
            QAbstractState *cs = lst.at(i);
            if (!isInFinalState(cs))
                return false;
        }
        return true;
    }
    else
        return false;
}

void QStateMachinePrivate::registerRestorable(QObject *object, const QByteArray &propertyName)
{
    RestorableId id(object, propertyName);
    if (!registeredRestorables.contains(id))
        registeredRestorables.insert(id, object->property(propertyName));
}

QList<QPropertyAssignment> QStateMachinePrivate::restorablesToPropertyList(const QHash<RestorableId, QVariant> &restorables) const
{
    QList<QPropertyAssignment> result;
    QHash<RestorableId, QVariant>::const_iterator it;
    for (it = restorables.constBegin(); it != restorables.constEnd(); ++it) {
//        qDebug() << "restorable:" << it.key().first << it.key().second << it.value();
        result.append(QPropertyAssignment(it.key().first, it.key().second, it.value(), /*explicitlySet=*/false));
    }
    return result;
}

/*! 
   \internal
   Returns true if the variable with the given \a id has been registered for restoration.
*/
bool QStateMachinePrivate::hasRestorable(QObject *object, const QByteArray &propertyName) const
{
    return registeredRestorables.contains(RestorableId(object, propertyName));
}

QVariant QStateMachinePrivate::restorableValue(QObject *object, const QByteArray &propertyName) const
{
    return registeredRestorables.value(RestorableId(object, propertyName), QVariant());
}


/*!
   \internal
    Unregisters the variable identified by \a id
*/
void QStateMachinePrivate::unregisterRestorable(QObject *object, const QByteArray &propertyName)
{
//    qDebug() << "unregisterRestorable(" << object << propertyName << ')';
    RestorableId id(object, propertyName);
    registeredRestorables.remove(id);
}

QAbstractState *QStateMachinePrivate::findErrorState(QAbstractState *context)
{
    // If the user sets the root state's error state to 0, we return the initial error state
    if (context == 0)
        return initialErrorStateForRoot;

    // Find error state recursively in parent hierarchy if not set explicitly for context state
    QAbstractState *errorState = 0;
    
    QState *s = qobject_cast<QState*>(context);
    if (s)
        errorState = s->errorState();

    if (!errorState)
        errorState = findErrorState(context->parentState());
    
    return errorState;   
}

void QStateMachinePrivate::setError(QStateMachine::Error errorCode, QAbstractState *currentContext)
{
    error = errorCode;

    switch (errorCode) {
    case QStateMachine::NoInitialStateError:        
        Q_ASSERT(currentContext != 0);

        errorString = QStateMachine::tr("Missing initial state in compound state '%1'")
                        .arg(currentContext->objectName());

        break;
    case QStateMachine::NoDefaultStateInHistoryStateError:
        Q_ASSERT(currentContext != 0);

        errorString = QStateMachine::tr("Missing default state in history state '%1'")
                        .arg(currentContext->objectName());
        break;

    case QStateMachine::NoCommonAncestorForTransitionError:
        Q_ASSERT(currentContext != 0);

        errorString = QStateMachine::tr("No common ancestor for targets and source of transition from state '%1'")
                        .arg(currentContext->objectName());
        break;
    default:
        errorString = QStateMachine::tr("Unknown error");
    };

    pendingErrorStates.clear(); 
    pendingErrorStatesForDefaultEntry.clear();

    QAbstractState *currentErrorState = findErrorState(currentContext);

    // Avoid infinite loop if the error state itself has an error
    if (currentContext == currentErrorState) {
        Q_ASSERT(currentContext != initialErrorStateForRoot); // RootErrorState is broken
        currentErrorState = initialErrorStateForRoot;
    }

    Q_ASSERT(currentErrorState != 0);
    Q_ASSERT(currentErrorState != rootState);
    
    QState *lca = findLCA(QList<QAbstractState*>() << currentErrorState << currentContext);
    addStatesToEnter(currentErrorState, lca, pendingErrorStates, pendingErrorStatesForDefaultEntry);
}

#ifndef QT_NO_ANIMATION

QPair<QList<QAbstractAnimation*>, QList<QAbstractAnimation*> >
QStateMachinePrivate::initializeAnimation(QAbstractAnimation *abstractAnimation, 
                                          const QPropertyAssignment &prop)
{
    QList<QAbstractAnimation*> handledAnimations;
    QList<QAbstractAnimation*> localResetEndValues;
    QAnimationGroup *group = qobject_cast<QAnimationGroup*>(abstractAnimation);
    if (group) {
        for (int i = 0; i < group->animationCount(); ++i) {
            QAbstractAnimation *animationChild = group->animationAt(i);
            QPair<QList<QAbstractAnimation*>, QList<QAbstractAnimation*> > ret;
            ret = initializeAnimation(animationChild, prop);
            handledAnimations << ret.first;
            localResetEndValues << ret.second;
        }
    } else { 
        QPropertyAnimation *animation = qobject_cast<QPropertyAnimation *>(abstractAnimation);
        if (animation != 0 
            && prop.object == animation->targetObject()
            && prop.propertyName == animation->propertyName()) {

            // Only change end value if it is undefined
            if (!animation->endValue().isValid()) {
                animation->setEndValue(prop.value);
                localResetEndValues.append(animation);
            }
            handledAnimations.append(animation);
        }
    }
    return qMakePair(handledAnimations, localResetEndValues);
}

void QStateMachinePrivate::_q_animationFinished()
{
    Q_Q(QStateMachine);
    QAbstractAnimation *anim = qobject_cast<QAbstractAnimation*>(q->sender());
    Q_ASSERT(anim != 0);
    QObject::disconnect(anim, SIGNAL(finished()), q, SLOT(_q_animationFinished()));
    if (resetAnimationEndValues.contains(anim)) {
        qobject_cast<QVariantAnimation*>(anim)->setEndValue(QVariant()); // ### generalize
        resetAnimationEndValues.remove(anim);
    }

    // Set the final property value.
    QPropertyAssignment assn = propertyForAnimation.take(anim);
    Q_ASSERT(assn.object != 0);
    assn.object->setProperty(assn.propertyName, assn.value);
    if (!assn.explicitlySet)
        unregisterRestorable(assn.object, assn.propertyName);

    QAbstractState *state = stateForAnimation.take(anim);
    Q_ASSERT(state != 0);
    QHash<QAbstractState*, QList<QAbstractAnimation*> >::iterator it;
    it = animationsForState.find(state);
    Q_ASSERT(it != animationsForState.end());
    QList<QAbstractAnimation*> &animations = it.value();
    animations.removeOne(anim);
    if (animations.isEmpty()) {
        animationsForState.erase(it);
        QStatePrivate::get(qobject_cast<QState*>(state))->emitPolished();
    }
}

#endif // !QT_NO_ANIMATION

namespace {

class StartState : public QState
{
public:
    StartState(QState *parent)
        : QState(parent) {}
protected:
    void onEntry(QEvent *) {}
    void onExit(QEvent *) {}
};

class InitialTransition : public QAbstractTransition
{
public:
    InitialTransition(QAbstractState *target)
        : QAbstractTransition(QList<QAbstractState*>() << target) {}
protected:
    virtual bool eventTest(QEvent *) { return true; }
    virtual void onTransition(QEvent *) {}
};

} // namespace

void QStateMachinePrivate::_q_start()
{
    Q_Q(QStateMachine);
    Q_ASSERT(state == Starting);
    if (!rootState) {
        state = NotRunning;
        return;
    }
    QAbstractState *initial = rootState->initialState();
    if (initial == 0)
        setError(QStateMachine::NoInitialStateError, rootState);    

    configuration.clear();
    qDeleteAll(internalEventQueue);
    internalEventQueue.clear();
    qDeleteAll(externalEventQueue);
    externalEventQueue.clear();

#ifdef QSTATEMACHINE_DEBUG
    qDebug() << q << ": starting";
#endif
    state = Running;
    processingScheduled = true; // we call _q_process() below
    emit q->started();

    StartState *start = new StartState(rootState);
    QAbstractTransition *initialTransition = new InitialTransition(initial);
    start->addTransition(initialTransition);
    QList<QAbstractTransition*> transitions;
    transitions.append(initialTransition);
    QEvent nullEvent(QEvent::None);
    executeTransitionContent(&nullEvent, transitions);
    QList<QAbstractState*> enteredStates = enterStates(&nullEvent, transitions);
    applyProperties(transitions, QList<QAbstractState*>() << start,
                    enteredStates);
    delete start;

#ifdef QSTATEMACHINE_DEBUG
    qDebug() << q << ": initial configuration:" << configuration;
#endif
    _q_process();
}

void QStateMachinePrivate::_q_process()
{
    Q_Q(QStateMachine);
    Q_ASSERT(state == Running);
    Q_ASSERT(!processing);
    processing = true;
    processingScheduled = false;
#ifdef QSTATEMACHINE_DEBUG
    qDebug() << q << ": starting the event processing loop";
#endif
    while (processing) {
        if (stop) {
            stop = false;
            processing = false;
            stopProcessingReason = Stopped;
            break;
        }
        QSet<QAbstractTransition*> enabledTransitions;
        QEvent *e = new QEvent(QEvent::None);
        enabledTransitions = selectTransitions(e);
        if (enabledTransitions.isEmpty()) {
            delete e;
            e = 0;
        }
        if (enabledTransitions.isEmpty() && !internalEventQueue.isEmpty()) {
            e = internalEventQueue.takeFirst();
#ifdef QSTATEMACHINE_DEBUG
            qDebug() << q << ": dequeued internal event" << e << "of type" << e->type();
#endif
            enabledTransitions = selectTransitions(e);
            if (enabledTransitions.isEmpty()) {
                delete e;
                e = 0;
            }
        }
        if (enabledTransitions.isEmpty()) {
            if (externalEventQueue.isEmpty()) {
                if (internalEventQueue.isEmpty()) {
                    processing = false;
                    stopProcessingReason = EventQueueEmpty;
                }
            } else {
                e = externalEventQueue.takeFirst();
#ifdef QSTATEMACHINE_DEBUG
                qDebug() << q << ": dequeued external event" << e << "of type" << e->type();
#endif
                enabledTransitions = selectTransitions(e);
                if (enabledTransitions.isEmpty()) {
                    delete e;
                    e = 0;
                }
            }
        }
        if (!enabledTransitions.isEmpty()) {
            q->beginMicrostep(e);
            microstep(e, enabledTransitions.toList());
            q->endMicrostep(e);
        }
#ifdef QSTATEMACHINE_DEBUG
        else {
            qDebug() << q << ": no transitions enabled";
        }
#endif
        delete e;
    }
#ifdef QSTATEMACHINE_DEBUG
    qDebug() << q << ": finished the event processing loop";
#endif
    switch (stopProcessingReason) {
    case EventQueueEmpty:
        break;
    case Finished:
        state = NotRunning;
        unregisterAllTransitions();
        emit q->finished();
        break;
    case Stopped:
        state = NotRunning;
        unregisterAllTransitions();
        emit q->stopped();
        break;
    }
}

void QStateMachinePrivate::scheduleProcess()
{
    if ((state != Running) || processing || processingScheduled)
        return;
    processingScheduled = true;
    QMetaObject::invokeMethod(q_func(), "_q_process", Qt::QueuedConnection);
}

void QStateMachinePrivate::registerTransitions(QAbstractState *state)
{
    QState *group = qobject_cast<QState*>(state);
    if (!group)
        return;
    QList<QAbstractTransition*> transitions = QStatePrivate::get(group)->transitions();
    for (int i = 0; i < transitions.size(); ++i) {
        QAbstractTransition *t = transitions.at(i);
        if (QSignalTransition *st = qobject_cast<QSignalTransition*>(t)) {
            registerSignalTransition(st);
        }
#ifndef QT_NO_STATEMACHINE_EVENTFILTER
        else if (QEventTransition *oet = qobject_cast<QEventTransition*>(t)) {
            registerEventTransition(oet);
        }
#endif
    }
}

void QStateMachinePrivate::unregisterTransition(QAbstractTransition *transition)
{
    if (QSignalTransition *st = qobject_cast<QSignalTransition*>(transition)) {
        unregisterSignalTransition(st);
    }
#ifndef QT_NO_STATEMACHINE_EVENTFILTER
    else if (QEventTransition *oet = qobject_cast<QEventTransition*>(transition)) {
        unregisterEventTransition(oet);
    }
#endif
}

void QStateMachinePrivate::registerSignalTransition(QSignalTransition *transition)
{
    Q_Q(QStateMachine);
    if (QSignalTransitionPrivate::get(transition)->signalIndex != -1)
        return; // already registered
    QObject *sender = QSignalTransitionPrivate::get(transition)->sender;
    if (!sender)
        return;
    QByteArray signal = QSignalTransitionPrivate::get(transition)->signal;
    if (signal.startsWith('0'+QSIGNAL_CODE))
        signal.remove(0, 1);
    const QMetaObject *meta = sender->metaObject();
    int signalIndex = meta->indexOfSignal(signal);
    if (signalIndex == -1) {
        signalIndex = meta->indexOfSignal(QMetaObject::normalizedSignature(signal));
        if (signalIndex == -1) {
            qWarning("QSignalTransition: no such signal: %s::%s",
                     meta->className(), signal.constData());
            return;
        }
    }
    QVector<int> &connectedSignalIndexes = connections[sender];
    if (connectedSignalIndexes.size() <= signalIndex)
        connectedSignalIndexes.resize(signalIndex+1);
    if (connectedSignalIndexes.at(signalIndex) == 0) {
        if (!signalEventGenerator)
            signalEventGenerator = new QSignalEventGenerator(q);
        bool ok = QMetaObject::connect(sender, signalIndex, signalEventGenerator,
                                       signalEventGenerator->metaObject()->methodOffset());
        if (!ok) {
#ifdef QSTATEMACHINE_DEBUG
            qDebug() << q << ": FAILED to add signal transition from" << transition->sourceState()
                     << ": ( sender =" << sender << ", signal =" << signal
                     << ", targets =" << transition->targetStates() << ')';
#endif
            return;
        }
    }
    ++connectedSignalIndexes[signalIndex];
    QSignalTransitionPrivate::get(transition)->signalIndex = signalIndex;
#ifdef QSTATEMACHINE_DEBUG
    qDebug() << q << ": added signal transition from" << transition->sourceState()
             << ": ( sender =" << sender << ", signal =" << signal
             << ", targets =" << transition->targetStates() << ')';
#endif
}

void QStateMachinePrivate::unregisterSignalTransition(QSignalTransition *transition)
{
    int signalIndex = QSignalTransitionPrivate::get(transition)->signalIndex;
    if (signalIndex == -1)
        return; // not registered
    QSignalTransitionPrivate::get(transition)->signalIndex = -1;
    const QObject *sender = QSignalTransitionPrivate::get(transition)->sender;
    QVector<int> &connectedSignalIndexes = connections[sender];
    Q_ASSERT(connectedSignalIndexes.size() > signalIndex);
    Q_ASSERT(connectedSignalIndexes.at(signalIndex) != 0);
    if (--connectedSignalIndexes[signalIndex] == 0) {
        Q_ASSERT(signalEventGenerator != 0);
        QMetaObject::disconnect(sender, signalIndex, signalEventGenerator,
                                signalEventGenerator->metaObject()->methodOffset());
        int sum = 0;
        for (int i = 0; i < connectedSignalIndexes.size(); ++i)
            sum += connectedSignalIndexes.at(i);
        if (sum == 0)
            connections.remove(sender);
    }
}

void QStateMachinePrivate::unregisterAllTransitions()
{
    {
        QList<QSignalTransition*> transitions = qFindChildren<QSignalTransition*>(rootState);
        for (int i = 0; i < transitions.size(); ++i)
            unregisterSignalTransition(transitions.at(i));
    }
    {
        QList<QEventTransition*> transitions = qFindChildren<QEventTransition*>(rootState);
        for (int i = 0; i < transitions.size(); ++i)
            unregisterEventTransition(transitions.at(i));
    }
}

#ifndef QT_NO_STATEMACHINE_EVENTFILTER
void QStateMachinePrivate::registerEventTransition(QEventTransition *transition)
{
    Q_Q(QStateMachine);
    if (QEventTransitionPrivate::get(transition)->registered)
        return;
    if (transition->eventType() >= QEvent::User) {
        qWarning("QObject event transitions are not supported for custom types");
        return;
    }
    QObject *object = QEventTransitionPrivate::get(transition)->object;
    if (!object)
        return;
    QObjectPrivate *od = QObjectPrivate::get(object);
    if (!od->eventFilters.contains(q))
        object->installEventFilter(q);
    ++qobjectEvents[object][transition->eventType()];
    QEventTransitionPrivate::get(transition)->registered = true;
#ifdef QSTATEMACHINE_DEBUG
    qDebug() << q << ": added event transition from" << transition->sourceState()
             << ": ( object =" << object << ", event =" << transition->eventType()
             << ", targets =" << transition->targetStates() << ')';
#endif
}

void QStateMachinePrivate::unregisterEventTransition(QEventTransition *transition)
{
    Q_Q(QStateMachine);
    if (!QEventTransitionPrivate::get(transition)->registered)
        return;
    QObject *object = QEventTransitionPrivate::get(transition)->object;
    QHash<QEvent::Type, int> &events = qobjectEvents[object];
    Q_ASSERT(events.value(transition->eventType()) > 0);
    if (--events[transition->eventType()] == 0) {
        events.remove(transition->eventType());
        int sum = 0;
        QHash<QEvent::Type, int>::const_iterator it;
        for (it = events.constBegin(); it != events.constEnd(); ++it)
            sum += it.value();
        if (sum == 0) {
            qobjectEvents.remove(object);
            object->removeEventFilter(q);
        }
    }
    QEventTransitionPrivate::get(transition)->registered = false;
}
#endif

void QStateMachinePrivate::handleTransitionSignal(const QObject *sender, int signalIndex,
                                                  void **argv)
{
    Q_ASSERT(connections[sender].at(signalIndex) != 0);
    const QMetaObject *meta = sender->metaObject();
    QMetaMethod method = meta->method(signalIndex);
    QList<QByteArray> parameterTypes = method.parameterTypes();
    int argc = parameterTypes.count();
    QList<QVariant> vargs;
    for (int i = 0; i < argc; ++i) {
        int type = QMetaType::type(parameterTypes.at(i));
        vargs.append(QVariant(type, argv[i+1]));
    }

#ifdef QSTATEMACHINE_DEBUG
    qDebug() << q_func() << ": sending signal event ( sender =" << sender
             << ", signal =" << sender->metaObject()->method(signalIndex).signature() << ')';
#endif
    internalEventQueue.append(new QSignalEvent(sender, signalIndex, vargs));
    scheduleProcess();
}

/*!
  Constructs a new state machine with the given \a parent.
*/
QStateMachine::QStateMachine(QObject *parent)
    : QObject(*new QStateMachinePrivate, parent)
{
}

/*!
  \internal
*/
QStateMachine::QStateMachine(QStateMachinePrivate &dd, QObject *parent)
    : QObject(dd, parent)
{
}

/*!
  Destroys this state machine.
*/
QStateMachine::~QStateMachine()
{
}

namespace {

class RootErrorState : public QAbstractState 
{
public:
    RootErrorState(QState *parent) 
        : QAbstractState(parent) 
    {
        setObjectName(QString::fromLatin1("DefaultErrorState"));
    }

    void onEntry(QEvent *)
    {
        QAbstractStatePrivate *d = QAbstractStatePrivate::get(this);
        QStateMachine *machine = d->machine();

        qWarning("Unrecoverable error detected in running state machine: %s", 
                 qPrintable(machine->errorString()));
    }

    void onExit(QEvent *) {}
};

class RootState : public QState
{
public:
    RootState(QState *parent)
        : QState(parent)
    {                
    }

    void onEntry(QEvent *) {}
    void onExit(QEvent *) {}
};

} // namespace

/*!
  Returns this state machine's root state.
*/
QState *QStateMachine::rootState() const
{
    Q_D(const QStateMachine);
    if (!d->rootState) {
        const_cast<QStateMachinePrivate*>(d)->rootState = new RootState(0);
        const_cast<QStateMachinePrivate*>(d)->initialErrorStateForRoot = new RootErrorState(d->rootState);
        d->rootState->setParent(const_cast<QStateMachine*>(this));
        d->rootState->setErrorState(d->initialErrorStateForRoot);
    }
    return d->rootState;
}

/*!
  Returns the error state of the state machine's root state. 

  \sa QState::errorState()
*/
QAbstractState *QStateMachine::errorState() const
{
    return rootState()->errorState();
}

/*!
  Sets the error state of this state machine's root state to be \a state. When a running state 
  machine encounters an error which puts it in an undefined state, it will enter an error state 
  based on the context of the error that occurred. It will enter this state regardless of what 
  is currently in the event queue.
  
  If the erroneous state has an error state set, this will be entered by the machine. If no error
  state has been set, the state machine will search the parent hierarchy recursively for an 
  error state. The error state of the root state can thus be seen as a global error state that 
  applies for the states for which a more specific error state has not been set.
  
  Before entering the error state, the state machine will set the error code returned by error() and 
  error  message returned by errorString(). 

  The default error state will print a warning to the console containing the information returned by 
  errorString(). By setting a new error state on either the state machine itself, or on specific 
  states, you can fine tune error handling in the state machine. 

  If the root state's error state is set to 0, or if the error state selected by the machine itself
  contains an error, the default error state will be used.

  \sa QState::setErrorState(), rootState()
*/
void QStateMachine::setErrorState(QAbstractState *state)
{
    rootState()->setErrorState(state);
}

/*! \enum QStateMachine::Error 

    This enum type defines errors that can occur in the state machine at run time. When the state
    machine encounters an unrecoverable error at run time, it will set the error code returned 
    by error(), the error message returned by errorString(), and enter an error state based on 
    the context of the error.

    \value NoError No error has occurred.
    \value NoInitialStateError The machine has entered a QState with children which does not have an
           initial state set. The context of this error is the state which is missing an initial
           state.
    \value NoDefaultStateInHistoryStateError The machine has entered a QHistoryState which does not have 
           a default state set. The context of this error is the QHistoryState which is missing a
           default state.
    \value NoCommonAncestorForTransitionError The machine has selected a transition whose source 
           and targets are not part of the same tree of states, and thus are not part of the same 
           state machine. Commonly, this could mean that one of the states has not been given 
           any parent or added to any machine. The context of this error is the source state of 
           the transition.

    \sa setErrorState()
*/

/*!
   \enum QStateMachine::RestorePolicy

   This enum specifies the restore policy type. The restore policy
   takes effect when the machine enters a state which sets one or more
   properties. If the restore policy is set to RestoreProperties,
   the state machine will save the original value of the property before the
   new value is set.

   Later, when the machine either enters a state which does not set
   a value for the given property, the property will automatically be restored
   to its initial value.

   Only one initial value will be saved for any given property. If a value for a property has 
   already been saved by the state machine, it will not be overwritten until the property has been
   successfully restored. 

   \value DoNotRestoreProperties The state machine should not save the initial values of properties 
          and restore them later.
   \value RestoreProperties The state machine should save the initial values of properties 
          and restore them later.

   \sa QStateMachine::globalRestorePolicy QState::assignProperty()
*/


/*!
  Returns the error code of the last error that occurred in the state machine.
*/
QStateMachine::Error QStateMachine::error() const
{
    Q_D(const QStateMachine);
    return d->error;
}

/*!
  Returns the error string of the last error that occurred in the state machine.
*/
QString QStateMachine::errorString() const
{
    Q_D(const QStateMachine);
    return d->errorString;
}

/*!
  Clears the error string and error code of the state machine.
*/
void QStateMachine::clearError()
{
    Q_D(QStateMachine);
    d->errorString.clear();
    d->error = NoError;
}

/*!
   Returns the restore policy of the state machine.

   \sa setGlobalRestorePolicy()
*/
QStateMachine::RestorePolicy QStateMachine::globalRestorePolicy() const
{
    Q_D(const QStateMachine);
    return d->globalRestorePolicy;
}

/*!
   Sets the restore policy of the state machine to \a restorePolicy. The default 
   restore policy is QAbstractState::DoNotRestoreProperties.
   
   \sa globalRestorePolicy()
*/
void QStateMachine::setGlobalRestorePolicy(QStateMachine::RestorePolicy restorePolicy) 
{
    Q_D(QStateMachine);
    d->globalRestorePolicy = restorePolicy;
}

/*!
  Returns this state machine's initial state, or 0 if no initial state has
  been set.
*/
QAbstractState *QStateMachine::initialState() const
{
    Q_D(const QStateMachine);
    if (!d->rootState)
        return 0;
    return d->rootState->initialState();
}

/*!
  Sets this state machine's initial \a state.
*/
void QStateMachine::setInitialState(QAbstractState *state)
{
    Q_D(QStateMachine);
    if (!d->rootState) {
        if (!state)
            return;
        rootState()->setInitialState(state);
    }
    d->rootState->setInitialState(state);
}

/*!
  Adds the given \a state to this state machine. The state becomes a top-level
  state (i.e. a child of the rootState()).

  If the state is already in a different machine, it will first be removed
  from its old machine, and then added to this machine.

  \sa removeState(), rootState(), setInitialState()
*/
void QStateMachine::addState(QAbstractState *state)
{
    if (!state) {
        qWarning("QStateMachine::addState: cannot add null state");
        return;
    }
    if (QAbstractStatePrivate::get(state)->machine() == this) {
        qWarning("QStateMachine::addState: state has already been added to this machine");
        return;
    }
    state->setParent(rootState());
}

/*!
  Removes the given \a state from this state machine.  The state machine
  releases ownership of the state.

  \sa addState()
*/
void QStateMachine::removeState(QAbstractState *state)
{
    if (!state) {
        qWarning("QStateMachine::removeState: cannot remove null state");
        return;
    }
    if (QAbstractStatePrivate::get(state)->machine() != this) {
        qWarning("QStateMachine::removeState: state %p's machine (%p)"
                 " is different from this machine (%p)",
                 state, QAbstractStatePrivate::get(state)->machine(), this);
        return;
    }
    state->setParent(0);
}

/*!
  Returns whether this state machine is running.

  start(), stop()
*/
bool QStateMachine::isRunning() const
{
    Q_D(const QStateMachine);
    return (d->state == QStateMachinePrivate::Running);
}

/*!
  Starts this state machine.  The machine will reset its configuration and
  transition to the initial state.  When a final top-level state (QFinalState)
  is entered, the machine will emit the finished() signal.

  \sa started(), finished(), stop(), initialState()
*/
void QStateMachine::start()
{
    Q_D(QStateMachine);

    if (rootState()->initialState() == 0) {
        qWarning("QStateMachine::start: No initial state set for machine. Refusing to start.");
        return;
    }

    switch (d->state) {
    case QStateMachinePrivate::NotRunning:
        d->state = QStateMachinePrivate::Starting;
        QMetaObject::invokeMethod(this, "_q_start", Qt::QueuedConnection);
        break;
    case QStateMachinePrivate::Starting:
        break;
    case QStateMachinePrivate::Running:
        qWarning("QStateMachine::start(): already running");
        break;
    }
}

/*!
  Stops this state machine. The state machine will stop processing events and
  then emit the stopped() signal.

  \sa stopped(), start()
*/
void QStateMachine::stop()
{
    Q_D(QStateMachine);
    switch (d->state) {
    case QStateMachinePrivate::NotRunning:
        break;
    case QStateMachinePrivate::Starting:
        // the machine will exit as soon as it enters the event processing loop
        d->stop = true;
        break;
    case QStateMachinePrivate::Running:
        d->stop = true;
        d->scheduleProcess();
        break;
    }
}

/*!
  Posts the given \a event for processing by this state machine, with a delay
  of \a delay milliseconds.

  This function returns immediately. The event is added to the state machine's
  event queue. Events are processed in the order posted. The state machine
  takes ownership of the event and deletes it once it has been processed.

  You can only post events when the state machine is running.
*/
void QStateMachine::postEvent(QEvent *event, int delay)
{
    Q_D(QStateMachine);
    if (d->state != QStateMachinePrivate::Running) {
        qWarning("QStateMachine::postEvent: cannot post event when the state machine is not running");
        return;
    }
#ifdef QSTATEMACHINE_DEBUG
    qDebug() << this << ": posting external event" << event << "with delay" << delay;
#endif
    if (delay) {
        int tid = startTimer(delay);
        d->delayedEvents[tid] = event;
    } else {
        d->externalEventQueue.append(event);
        d->scheduleProcess();
    }
}

/*!
  \internal

  Posts the given internal \a event for processing by this state machine.
*/
void QStateMachine::postInternalEvent(QEvent *event)
{
    Q_D(QStateMachine);
#ifdef QSTATEMACHINE_DEBUG
    qDebug() << this << ": posting internal event" << event;
#endif
    d->internalEventQueue.append(event);
    d->scheduleProcess();
}

/*!
  \internal

   Returns the maximal consistent set of states (including parallel and final
   states) that this state machine is currently in. If a state \c s is in the
   configuration, it is always the case that the parent of \c s is also in
   c. Note, however, that the rootState() is not an explicit member of the
   configuration.
*/
QSet<QAbstractState*> QStateMachine::configuration() const
{
    Q_D(const QStateMachine);
    return d->configuration;
}

/*!
  \fn QStateMachine::started()

  This signal is emitted when the state machine has entered its initial state
  (QStateMachine::initialState).

  \sa QStateMachine::finished(), QStateMachine::start()
*/

/*!
  \fn QStateMachine::finished()

  This signal is emitted when the state machine has reached a top-level final
  state (QFinalState).

  \sa QStateMachine::started()
*/

/*!
  \fn QStateMachine::stopped()

  This signal is emitted when the state machine has stopped.

  \sa QStateMachine::stop(), QStateMachine::finished()
*/

/*!
  \reimp
*/
bool QStateMachine::event(QEvent *e)
{
    Q_D(QStateMachine);
    if (e->type() == QEvent::Timer) {
        QTimerEvent *te = static_cast<QTimerEvent*>(e);
        int tid = te->timerId();
        if (d->delayedEvents.contains(tid)) {
            killTimer(tid);
            QEvent *ee = d->delayedEvents.take(tid);
            d->externalEventQueue.append(ee);
            d->scheduleProcess();
            return true;
        }
    } else if (e->type() == QEvent::ChildAdded) {
        QChildEvent *ce = static_cast<QChildEvent*>(e);
        if (QAbstractState *state = qobject_cast<QAbstractState*>(ce->child())) {
            if (state != rootState()) {
                state->setParent(rootState());
                return true;
            }
        }
    }
    return QObject::event(e);
}

#ifndef QT_NO_STATEMACHINE_EVENTFILTER
/*!
  \reimp
*/
bool QStateMachine::eventFilter(QObject *watched, QEvent *event)
{
    Q_D(QStateMachine);
    Q_ASSERT(d->qobjectEvents.contains(watched));
    if (d->qobjectEvents[watched].contains(event->type()))
        postEvent(new QWrappedEvent(watched, d->handler->cloneEvent(event)));
    return false;
}
#endif

/*!
  \internal

  This function is called when the state machine is about to select
  transitions based on the given \a event.

  The default implementation does nothing.
*/
void QStateMachine::beginSelectTransitions(QEvent *event)
{
    Q_UNUSED(event);
}

/*!
  \internal

  This function is called when the state machine has finished selecting
  transitions based on the given \a event.

  The default implementation does nothing.
*/
void QStateMachine::endSelectTransitions(QEvent *event)
{
    Q_UNUSED(event);
}

/*!
  \internal

  This function is called when the state machine is about to do a microstep.

  The default implementation does nothing.
*/
void QStateMachine::beginMicrostep(QEvent *event)
{
    Q_UNUSED(event);
}

/*!
  \internal

  This function is called when the state machine has finished doing a
  microstep.

  The default implementation does nothing.
*/
void QStateMachine::endMicrostep(QEvent *event)
{
    Q_UNUSED(event);
}

#ifndef QT_NO_ANIMATION

/*!
  Returns whether animations are enabled for this state machine.
*/
bool QStateMachine::animationsEnabled() const
{
    Q_D(const QStateMachine);
    return d->animationsEnabled;
}

/*!
  Sets whether animations are \a enabled for this state machine.
*/
void QStateMachine::setAnimationsEnabled(bool enabled)
{
    Q_D(QStateMachine);
    d->animationsEnabled = enabled;
}

/*!
    Adds a default \a animation to be considered for any transition.
*/    
void QStateMachine::addDefaultAnimation(QAbstractAnimation *animation)
{
    Q_D(QStateMachine);
    d->defaultAnimations.append(animation);
}

/*!
    Returns the list of default animations that will be considered for any transition.
*/
QList<QAbstractAnimation*> QStateMachine::defaultAnimations() const
{    
    Q_D(const QStateMachine);
    return d->defaultAnimations;
}

/*!
    Removes \a animation from the list of default animations. 
*/
void QStateMachine::removeDefaultAnimation(QAbstractAnimation *animation)
{
    Q_D(QStateMachine);
    d->defaultAnimations.removeAll(animation);
}

#endif // QT_NO_ANIMATION


static const uint qt_meta_data_QSignalEventGenerator[] = {

 // content:
       2,       // revision
       0,       // classname
       0,    0, // classinfo
       1,   12, // methods
       0,    0, // properties
       0,    0, // enums/sets
       0,    0, // constructors

 // slots: signature, parameters, type, tag, flags
      23,   22,   22,   22, 0x0a,

       0        // eod
};

static const char qt_meta_stringdata_QSignalEventGenerator[] = {
    "QSignalEventGenerator\0\0execute()\0"
};

const QMetaObject QSignalEventGenerator::staticMetaObject = {
    { &QObject::staticMetaObject, qt_meta_stringdata_QSignalEventGenerator,
      qt_meta_data_QSignalEventGenerator, 0 }
};

const QMetaObject *QSignalEventGenerator::metaObject() const
{
    return &staticMetaObject;
}

void *QSignalEventGenerator::qt_metacast(const char *_clname)
{
    if (!_clname) return 0;
    if (!strcmp(_clname, qt_meta_stringdata_QSignalEventGenerator))
        return static_cast<void*>(const_cast< QSignalEventGenerator*>(this));
    return QObject::qt_metacast(_clname);
}

int QSignalEventGenerator::qt_metacall(QMetaObject::Call _c, int _id, void **_a)
{
    _id = QObject::qt_metacall(_c, _id, _a);
    if (_id < 0)
        return _id;
    if (_c == QMetaObject::InvokeMetaMethod) {
        switch (_id) {
        case 0: {
// ### in Qt 4.6 we can use QObject::senderSignalIndex()
            QObjectPrivate *d = static_cast<QObjectPrivate *>(d_ptr);
            int signalIndex = -1;
            QObject *sender = this->sender();
            if (sender && d->currentSender)
                signalIndex = d->currentSender->signal;

            Q_ASSERT(signalIndex != -1);
            QStateMachine *machine = qobject_cast<QStateMachine*>(parent());
            QStateMachinePrivate::get(machine)->handleTransitionSignal(sender, signalIndex, _a);
            break;
        }
        default: ;
        }
        _id -= 1;
    }
    return _id;
}

QSignalEventGenerator::QSignalEventGenerator(QStateMachine *parent)
    : QObject(parent)
{
}

/*!
  \class QSignalEvent

  \brief The QSignalEvent class represents a Qt signal event.

  \since 4.6
  \ingroup statemachine

  A signal event is generated by a QStateMachine in response to a Qt
  signal. The QSignalTransition class provides a transition associated with a
  signal event. QSignalEvent is part of \l{The State Machine Framework}.

  The sender() function returns the object that generated the signal. The
  signalIndex() function returns the index of the signal. The arguments()
  function returns the arguments of the signal.

  \sa QSignalTransition
*/

/*!
  \internal

  Constructs a new QSignalEvent object with the given \a sender, \a
  signalIndex and \a arguments.
*/
QSignalEvent::QSignalEvent(const QObject *sender, int signalIndex,
                           const QList<QVariant> &arguments)
    : QEvent(QEvent::Signal), m_sender(sender),
      m_signalIndex(signalIndex), m_arguments(arguments)
{
}

/*!
  Destroys this QSignalEvent.
*/
QSignalEvent::~QSignalEvent()
{
}

/*!
  \fn QSignalEvent::sender() const

  Returns the object that emitted the signal.

  \sa QObject::sender()
*/

/*!
  \fn QSignalEvent::signalIndex() const

  Returns the index of the signal.

  \sa QMetaObject::indexOfSignal(), QMetaObject::method()
*/

/*!
  \fn QSignalEvent::arguments() const

  Returns the arguments of the signal.
*/


/*!
  \class QWrappedEvent

  \brief The QWrappedEvent class holds a clone of an event associated with a QObject.

  \since 4.6
  \ingroup statemachine

  A wrapped event is generated by a QStateMachine in response to a Qt
  event. The QEventTransition class provides a transition associated with a
  such an event. QWrappedEvent is part of \l{The State Machine Framework}.

  The object() function returns the object that generated the event. The
  event() function returns a clone of the original event.

  \sa QEventTransition
*/

/*!
  \internal

  Constructs a new QWrappedEvent object with the given \a object
  and \a event.
*/
QWrappedEvent::QWrappedEvent(QObject *object, QEvent *event)
    : QEvent(QEvent::Wrapped), m_object(object), m_event(event)
{
}

/*!
  Destroys this QWrappedEvent.
*/
QWrappedEvent::~QWrappedEvent()
{
}

/*!
  \fn QWrappedEvent::object() const

  Returns the object that the event is associated with.
*/

/*!
  \fn QWrappedEvent::event() const

  Returns a clone of the original event.
*/

QT_END_NAMESPACE

#include "moc_qstatemachine.cpp"

#endif //QT_NO_STATEMACHINE