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/******************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the QtScxml module.
**
** $QT_BEGIN_LICENSE:COMM$
**
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** $QT_END_LICENSE$
**
******************************************************************************/
#include "qscxmlcppdatamodel_p.h"
#include "qscxmlstatemachine.h"
QT_USE_NAMESPACE
using namespace QScxmlExecutableContent;
/*!
\class QScxmlCppDataModel
\brief C++ data-model for a QScxmlStateMachine
\since 5.6
\inmodule QtScxml
\sa QScxmlStateMachine QScxmlDataModel
The C++ data-model for SCXML that lets you write C++ code for expr attributes and script tags.
The "data part" of the data-model is backed by a subclass of QScxmlCppDataModel, for which the
QtSCXML compiler (qscxmlc) will generate the dispatch methods. It cannot be used when loading
an SCXML file at run-time.
Usage is through the datamodel attribute on the <scxml> tag:
\code
<scxml datamodel="cplusplus:TheDataModel:thedatamodel.h" ....>
\endcode
The format for the datamodel tag is cplusplus:<class-name>:<classdef-header>. So, for the example
above, there should be a file "thedatamodel.h" containing a sub-class of QScxmlCppDataModel,
containing at least the following:
\code
#include "qscxmlcppdatamodel.h"
class TheDataModel: public QScxmlCppDataModel
{
Q_SCXML_DATAMODEL
public:
~TheDataModel();
};
\endcode
The Q_SCXML_DATAMODEL has to appear in the private section of the class definition, for example
right after the opening bracket, or after a Q_OBJECT macro. The destructor is needed to tell
the C++ compiler where to generate the vtable, because this subclass implements some virtual
methods whose implementation is generated by qscxmlc.
\note You can of course inherit from both QScxmlCppDataModel and QObject.
The Scxml compiler will generate the various evaluateTo methods, and convert expressions and
scripts into lambdas inside those methods. For example:
\code
<scxml datamodel="cplusplus:TheDataModel:thedatamodel.h" xmlns="http://www.w3.org/2005/07/scxml" version="1.0" name="MediaPlayerStateMachine">
<state id="stopped">
<transition event="tap" cond="isValidMedia()" target="playing"/>
</state>
<state id="playing">
<onentry>
<script>
media = eventData().value(QStringLiteral("media")).toString();
</script>
<send type="qt:signal" event="playbackStarted">
<param name="media" expr="media"/>
</send>
</onentry>
</state>
</scxml>
\endcode
This will result in:
\code
bool TheDataModel::evaluateToBool(QScxmlExecutableContent::EvaluatorId id, bool *ok) {
// ....
return [this]()->bool{ return isValidMedia(); }();
// ....
}
QVariant TheDataModel::evaluateToVariant(QScxmlExecutableContent::EvaluatorId id, bool *ok) {
// ....
return [this]()->QVariant{ return media; }();
// ....
}
void TheDataModel::evaluateToVoid(QScxmlExecutableContent::EvaluatorId id, bool *ok) {
// ....
[this]()->void{ media = eventData().value(QStringLiteral("media")).toString(); }();
// ....
}
\endcode
So, you are not limited to call functions. In a script tag you can put zero or more C++ statements,
and in cond or expr attributes you can use any C++ expression that can be converted to the
respectively bool or QVariant. And, as the this pointer is also captured, you can call/access
the data model (the media attribute in the example above). For the full example, see
mediaplayer-cppdatamodel.
*/
/*!
* \brief Creates a new C++ data model.
*/
QScxmlCppDataModel::QScxmlCppDataModel(QScxmlStateMachine *stateMachine)
: QScxmlDataModel(stateMachine)
, data(new QScxmlCppDataModelPrivate)
{}
/*!
* \brief Destroys the C++ data model.
*/
QScxmlCppDataModel::~QScxmlCppDataModel()
{
delete data;
}
/*!
* \brief QScxmlCppDataModel::setup is called during state machine initialization.
*
* \param initialDataValues initial values for data-model variables specified by their keys. These
* are the values specified by <param> tags in an <invoke>.
*
* \sa QScxmlStateMachine::init
*/
bool QScxmlCppDataModel::setup(const QVariantMap &initialDataValues)
{
Q_UNUSED(initialDataValues);
return true;
}
/*!
* \internal not supported in this data-model
*/
void QScxmlCppDataModel::evaluateAssignment(EvaluatorId id, bool *ok)
{
Q_UNUSED(id);
Q_UNUSED(ok);
Q_UNREACHABLE();
}
/*!
* \internal not supported in this data-model
*/
void QScxmlCppDataModel::evaluateInitialization(EvaluatorId id, bool *ok)
{
Q_UNUSED(id);
Q_UNUSED(ok);
Q_UNREACHABLE();
}
/*!
* \internal not supported in this data-model
*/
bool QScxmlCppDataModel::evaluateForeach(EvaluatorId id, bool *ok, ForeachLoopBody *body)
{
Q_UNUSED(id);
Q_UNUSED(ok);
Q_UNUSED(body);
Q_UNREACHABLE();
return false;
}
/*!
* \brief Set the event that will be processed next.
*
* \sa QScxmlCppDataModel::event
*/
void QScxmlCppDataModel::setEvent(const QScxmlEvent &event)
{
data->event = event;
}
/*!
* \brief QScxmlCppDataModel::event holds the current event that is being processed by the
* state machine.
*
* See also section 5.10 in the Scxml specification for the description of the _event variable.
*
* \return the event currently being processed.
*/
const QScxmlEvent &QScxmlCppDataModel::event() const
{
return data->event;
}
/*!
* \internal not supported in this data-model
*/
QVariant QScxmlCppDataModel::property(const QString &name) const
{
Q_UNUSED(name);
return QVariant();
}
/*!
* \internal not supported in this data-model
*/
bool QScxmlCppDataModel::hasProperty(const QString &name) const
{
Q_UNUSED(name);
return false;
}
/*!
* \internal not supported in this data-model
*/
bool QScxmlCppDataModel::setProperty(const QString &name, const QVariant &value, const QString &context)
{
Q_UNUSED(name);
Q_UNUSED(value);
Q_UNUSED(context);
Q_UNREACHABLE();
return false;
}
/*!
* \return true if the state machine is in the state specified by stateName, false otherwise.
*/
bool QScxmlCppDataModel::In(const QString &stateName) const
{
return stateMachine()->isActive(stateName);
}
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