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

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#include "qstate.h"

#ifndef QT_NO_STATEMACHINE

#include "qstate_p.h"
#include "qhistorystate.h"
#include "qhistorystate_p.h"
#include "qabstracttransition.h"
#include "qabstracttransition_p.h"
#include "qsignaltransition.h"
#include "qstatemachine.h"
#include "qstatemachine_p.h"

QT_BEGIN_NAMESPACE

/*!
  \class QState

  \brief The QState class provides a general-purpose state for QStateMachine.

  \since 4.6
  \ingroup statemachine

  QState objects can have child states, and can have transitions to other
  states. QState is part of \l{The State Machine Framework}.

  The addTransition() function adds a transition. The removeTransition()
  function removes a transition.

  The assignProperty() function is used for defining property assignments that
  should be performed when a state is entered.

  Top-level states must be passed a QStateMachine object as their parent
  state, or added to a state machine using QStateMachine::addState().

  \section1 States with Child States

  The childMode property determines how child states are treated. For
  non-parallel state groups, the setInitialState() function must be called to
  set the initial state. The child states are mutually exclusive states, and
  the state machine needs to know which child state to enter when the parent
  state is the target of a transition.

  The state emits the QState::finished() signal when a final child state
  (QFinalState) is entered.

  The setErrorState() sets the state's error state. The error state is the
  state that the state machine will transition to if an error is detected when
  attempting to enter the state (e.g. because no initial state has been set).

*/

/*!
    \property QState::initialState

    \brief the initial state of this state (one of its child states)
*/

/*!
    \property QState::errorState

    \brief the error state of this state
*/

/*!
    \property QState::childMode

    \brief the child mode of this state

    The default value of this property is QState::ExclusiveStates.
*/

/*!
  \enum QState::ChildMode

  This enum specifies how a state's child states are treated.

  \value ExclusiveStates The child states are mutually exclusive and an
  initial state must be set by calling QState::setInitialState().

  \value ParallelStates The child states are parallel. When the parent state
  is entered, all its child states are entered in parallel.
*/

QStatePrivate::QStatePrivate()
    : errorState(0), initialState(0), childMode(QState::ExclusiveStates)
{
}

QStatePrivate::~QStatePrivate()
{
}

void QStatePrivate::emitFinished()
{
    Q_Q(QState);
    emit q->finished();
}

void QStatePrivate::emitPolished()
{
    Q_Q(QState);
    emit q->polished();
}

/*!
  Constructs a new state with the given \a parent state.
*/
QState::QState(QState *parent)
    : QAbstractState(*new QStatePrivate, parent)
{
}

/*!
  Constructs a new state with the given \a childMode and the given \a parent
  state.
*/
QState::QState(ChildMode childMode, QState *parent)
    : QAbstractState(*new QStatePrivate, parent)
{
    Q_D(QState);
    d->childMode = childMode;
}

/*!
  \internal
*/
QState::QState(QStatePrivate &dd, QState *parent)
    : QAbstractState(dd, parent)
{
}

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

QList<QAbstractState*> QStatePrivate::childStates() const
{
    QList<QAbstractState*> result;
    QList<QObject*>::const_iterator it;
    for (it = children.constBegin(); it != children.constEnd(); ++it) {
        QAbstractState *s = qobject_cast<QAbstractState*>(*it);
        if (!s || qobject_cast<QHistoryState*>(s))
            continue;
        result.append(s);
    }
    return result;
}

QList<QHistoryState*> QStatePrivate::historyStates() const
{
    QList<QHistoryState*> result;
    QList<QObject*>::const_iterator it;
    for (it = children.constBegin(); it != children.constEnd(); ++it) {
        QHistoryState *h = qobject_cast<QHistoryState*>(*it);
        if (h)
            result.append(h);
    }
    return result;
}

QList<QAbstractTransition*> QStatePrivate::transitions() const
{
    QList<QAbstractTransition*> result;
    QList<QObject*>::const_iterator it;
    for (it = children.constBegin(); it != children.constEnd(); ++it) {
        QAbstractTransition *t = qobject_cast<QAbstractTransition*>(*it);
        if (t)
            result.append(t);
    }
    return result;
}

#ifndef QT_NO_PROPERTIES

/*!
  Instructs this state to set the property with the given \a name of the given
  \a object to the given \a value when the state is entered.

  \sa polished()
*/
void QState::assignProperty(QObject *object, const char *name,
                            const QVariant &value)
{
    Q_D(QState);
    if (!object) {
        qWarning("QState::assignProperty: cannot assign property '%s' of null object", name);
        return;
    }
    for (int i = 0; i < d->propertyAssignments.size(); ++i) {
        QPropertyAssignment &assn = d->propertyAssignments[i];
        if ((assn.object == object) && (assn.propertyName == name)) {
            assn.value = value;
            return;
        }
    }
    d->propertyAssignments.append(QPropertyAssignment(object, name, value));
}

#endif // QT_NO_PROPERTIES

/*!
  Returns this state's error state. 

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

/*!
  Sets this state's error state to be the given \a state. If the error state
  is not set, or if it is set to 0, the state will inherit its parent's error
  state recursively. If no error state is set for the state itself or any of 
  its ancestors, an error will cause the machine to stop executing and an error
  will be printed to the console.
*/
void QState::setErrorState(QAbstractState *state)
{
    Q_D(QState);
    if (state != 0 && qobject_cast<QStateMachine*>(state)) {
        qWarning("QStateMachine::setErrorState: root state cannot be error state");
        return;
    }
    if (state != 0 && (!state->machine() || ((state->machine() != machine()) && !qobject_cast<QStateMachine*>(this)))) {
        qWarning("QState::setErrorState: error state cannot belong "
                 "to a different state machine");
        return;
    }

    d->errorState = state;
}

/*!
  Adds the given \a transition. The transition has this state as the source.
  This state takes ownership of the transition. If the transition is successfully
  added, the function will return the \a transition pointer. Otherwise it will return null.
*/
QAbstractTransition *QState::addTransition(QAbstractTransition *transition)
{
    Q_D(QState);
    if (!transition) {
        qWarning("QState::addTransition: cannot add null transition");
        return 0;
    }

    transition->setParent(this);
    const QList<QPointer<QAbstractState> > &targets = QAbstractTransitionPrivate::get(transition)->targetStates;
    for (int i = 0; i < targets.size(); ++i) {
        QAbstractState *t = targets.at(i);
        if (!t) {
            qWarning("QState::addTransition: cannot add transition to null state");
            return 0;
        }
        if ((QAbstractStatePrivate::get(t)->machine() != d->machine())
            && QAbstractStatePrivate::get(t)->machine() && d->machine()) {
            qWarning("QState::addTransition: cannot add transition "
                     "to a state in a different state machine");
            return 0;
        }
    }
    if (machine() != 0 && machine()->configuration().contains(this))
        QStateMachinePrivate::get(machine())->registerTransitions(this);
    return transition;
}

/*!
  Adds a transition associated with the given \a signal of the given \a sender
  object, and returns the new QSignalTransition object. The transition has
  this state as the source, and the given \a target as the target state.
*/
QSignalTransition *QState::addTransition(QObject *sender, const char *signal,
                                         QAbstractState *target)
{
    if (!sender) {
        qWarning("QState::addTransition: sender cannot be null");
        return 0;
    }
    if (!signal) {
        qWarning("QState::addTransition: signal cannot be null");
        return 0;
    }
    if (!target) {
        qWarning("QState::addTransition: cannot add transition to null state");
        return 0;
    }
    int offset = (*signal == '0'+QSIGNAL_CODE) ? 1 : 0;
    const QMetaObject *meta = sender->metaObject();
    if (meta->indexOfSignal(signal+offset) == -1) {
        if (meta->indexOfSignal(QMetaObject::normalizedSignature(signal+offset)) == -1) {
            qWarning("QState::addTransition: no such signal %s::%s",
                     meta->className(), signal+offset);
            return 0;
        }
    }
    QSignalTransition *trans = new QSignalTransition(sender, signal);
    trans->setTargetState(target);
    addTransition(trans);
    return trans;
}

namespace {

// ### Make public?
class UnconditionalTransition : public QAbstractTransition
{
public:
    UnconditionalTransition(QAbstractState *target)
        : QAbstractTransition()
    { setTargetState(target); }
protected:
    void onTransition(QEvent *) {}
    bool eventTest(QEvent *) { return true; }
};

} // namespace

/*!
  Adds an unconditional transition from this state to the given \a target
  state, and returns then new transition object.
*/
QAbstractTransition *QState::addTransition(QAbstractState *target)
{
    if (!target) {
        qWarning("QState::addTransition: cannot add transition to null state");
        return 0;
    }
    UnconditionalTransition *trans = new UnconditionalTransition(target);
    return addTransition(trans);
}

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

  \sa addTransition()
*/
void QState::removeTransition(QAbstractTransition *transition)
{
    Q_D(QState);
    if (!transition) {
        qWarning("QState::removeTransition: cannot remove null transition");
        return;
    }
    if (transition->sourceState() != this) {
        qWarning("QState::removeTransition: transition %p's source state (%p)"
                 " is different from this state (%p)",
                 transition, transition->sourceState(), this);
        return;
    }
    QStateMachinePrivate *mach = QStateMachinePrivate::get(d->machine());
    if (mach)
        mach->unregisterTransition(transition);
    transition->setParent(0);
}

/*!
  \reimp
*/
void QState::onEntry(QEvent *event)
{
    Q_UNUSED(event);
}

/*!
  \reimp
*/
void QState::onExit(QEvent *event)
{
    Q_UNUSED(event);
}

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

/*!
  Sets this state's initial state to be the given \a state.
  \a state has to be a child of this state.
*/
void QState::setInitialState(QAbstractState *state)
{
    Q_D(QState);
    if (d->childMode == QState::ParallelStates) {
        qWarning("QState::setInitialState: ignoring attempt to set initial state "
                 "of parallel state group %p", this);
        return;
    }
    if (state && (state->parentState() != this)) {
        qWarning("QState::setInitialState: state %p is not a child of this state (%p)",
                 state, this);
        return;
    }
    d->initialState = state;
}

/*!
  Returns the child mode of this state.
*/
QState::ChildMode QState::childMode() const
{
    Q_D(const QState);
    return d->childMode;
}

/*!
  Sets the child \a mode of this state.
*/
void QState::setChildMode(ChildMode mode)
{
    Q_D(QState);
    d->childMode = mode;
}

/*!
  \reimp
*/
bool QState::event(QEvent *e)
{
    return QAbstractState::event(e);
}

/*!
  \fn QState::finished()

  This signal is emitted when a final child state of this state is entered.

  \sa QFinalState
*/

/*!
  \fn QState::polished()

  This signal is emitted when all properties have been assigned their final value.

  \sa QState::assignProperty(), QAbstractTransition::addAnimation()
*/

QT_END_NAMESPACE

#endif //QT_NO_STATEMACHINE