Automatically initialize state machines when starting

This removes the need to call init() before start(), making the API
much more intuitive. We also expose the initial values as a Q_PROPERTY
so that they can be set in a declarative way from QML.

Change-Id: If3c995c956764018bcab7b6caa8485e32bba6f1a
Reviewed-by: Erik Verbruggen <erik.verbruggen@theqtcompany.com>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@theqtcompany.com>

5 files changed, 72 insertions, 13 deletions

diff --git a/src/imports/scxmlstatemachine/statemachineloader.cpp b/src/imports/scxmlstatemachine/statemachineloader.cpp
index ffdfca9..2062ab6 100644
--- a/src/imports/scxmlstatemachine/statemachineloader.cpp
+++ b/src/imports/scxmlstatemachine/statemachineloader.cpp
@@ -135,7 +135,6 @@ bool QScxmlStateMachineLoader::parse(const QUrl &filename)
 
     m_stateMachine = QScxmlStateMachine::fromData(&buf, filename.toString());
     m_stateMachine->setParent(this);
-    m_stateMachine->init();
 
     if (m_stateMachine->parseErrors().isEmpty()) {
         emit stateMachineChanged();
diff --git a/src/scxml/qscxmlinvokableservice.cpp b/src/scxml/qscxmlinvokableservice.cpp
index f9f2c67..ca64cdb 100644
--- a/src/scxml/qscxmlinvokableservice.cpp
+++ b/src/scxml/qscxmlinvokableservice.cpp
@@ -245,7 +245,8 @@ bool QScxmlInvokableScxml::start()
         return false;
 
     m_stateMachine->setSessionId(id);
-    if (m_stateMachine->init(data)) {
+    m_stateMachine->setInitialValues(data);
+    if (m_stateMachine->init()) {
         qCDebug(qscxmlLog) << parentStateMachine() << "starting" << m_stateMachine;
         m_stateMachine->start();
         return true;
diff --git a/src/scxml/qscxmlstatemachine.cpp b/src/scxml/qscxmlstatemachine.cpp
index eeca441..2522ade 100644
--- a/src/scxml/qscxmlstatemachine.cpp
+++ b/src/scxml/qscxmlstatemachine.cpp
@@ -223,6 +223,7 @@ QScxmlStateMachinePrivate::QScxmlStateMachinePrivate()
     : QObjectPrivate()
     , m_sessionId(QScxmlStateMachine::generateSessionId(QStringLiteral("session-")))
     , m_isInvoked(false)
+    , m_isInitialized(false)
     , m_dataModel(Q_NULLPTR)
     , m_dataBinding(QScxmlStateMachine::EarlyBinding)
     , m_executionEngine(Q_NULLPTR)
@@ -464,14 +465,32 @@ QScxmlStateMachine::QScxmlStateMachine(QScxmlStateMachinePrivate &dd, QObject *p
     \l {SCXML Specification - 5 Data Model and Data Manipulation}. For more
     information about supported data models, see \l {SCXML Compliance}.
 
-    Changing the data model while the state machine is \c running is not
-    specified in the SCXML standard and leads to undefined behavior.
+    Changing the data model when the state machine has been \c initialized is
+    not specified in the SCXML standard and leads to undefined behavior.
 
     \sa QScxmlDataModel, QScxmlNullDataModel, QScxmlEcmaScriptDataModel,
         QScxmlCppDataModel
 */
 
 /*!
+    \property QScxmlStateMachine::initialized
+
+    \brief Whether the state machine has been initialized.
+
+    It is \c true if the state machine has been initialized, \c false otherwise.
+
+    \sa QScxmlStateMachine::init(), QScxmlDataModel
+*/
+
+/*!
+    \property QScxmlStateMachine::initialValues
+
+    \brief The initial values to be used for setting up the data model.
+
+    \sa QScxmlStateMachine::init(), QScxmlDataModel
+*/
+
+/*!
     \enum QScxmlStateMachine::BindingMethod
 
     This enum specifies the binding method. The binding method controls the point in time
@@ -535,6 +554,12 @@ bool QScxmlStateMachine::isInvoked() const
     return d->m_isInvoked;
 }
 
+bool QScxmlStateMachine::isInitialized() const
+{
+    Q_D(const QScxmlStateMachine);
+    return d->m_isInitialized;
+}
+
 /*!
  * Sets the data model for this state machine to \a model. There is a 1:1
  * relation between state machines and models. After setting the model once you
@@ -990,25 +1015,31 @@ void QScxmlStateMachine::setScxmlEventFilter(QScxmlEventFilter *newFilter)
  * Initializes the state machine.
  *
  * State machine initialization consists of calling QScxmlDataModel::setup(), setting the initial
- * values for \c <data> elements, and executing any \c <script> tags of the \c <scxml> tag.
- *
- * \a initialDataValues contains initial values for data elements from the \c <invoke> tag.
- * These values will be used instead of the initial values from the \c <data> elements.
+ * values for \c <data> elements, and executing any \c <script> tags of the \c <scxml> tag. The
+ * initial data values are taken from the \c initialValues property.
  *
  * Returns \c false if parse errors occur or if any of the initialization steps fail.
  * Returns \c true otherwise.
  */
-bool QScxmlStateMachine::init(const QVariantMap &initialDataValues)
+bool QScxmlStateMachine::init()
 {
     Q_D(QScxmlStateMachine);
 
+    if (d->m_isInitialized)
+        return false;
+
     if (!parseErrors().isEmpty())
         return false;
 
-    if (!dataModel() || !dataModel()->setup(initialDataValues))
+    if (!dataModel() || !dataModel()->setup(d->m_initialValues))
+        return false;
+
+    if (!d->executeInitialSetup())
         return false;
 
-    return d->executeInitialSetup();
+    d->m_isInitialized = true;
+    emit initializedChanged(true);
+    return true;
 }
 
 /*!
@@ -1036,6 +1067,21 @@ void QScxmlStateMachine::setRunning(bool running)
         stop();
 }
 
+QVariantMap QScxmlStateMachine::initialValues()
+{
+    Q_D(const QScxmlStateMachine);
+    return d->m_initialValues;
+}
+
+void QScxmlStateMachine::setInitialValues(const QVariantMap &initialValues)
+{
+    Q_D(QScxmlStateMachine);
+    if (initialValues != d->m_initialValues) {
+        d->m_initialValues = initialValues;
+        emit initialValuesChanged(initialValues);
+    }
+}
+
 /*!
  * Returns the name of the state machine as set by the \e name attribute of the \c <scxml> tag.
  */
@@ -1237,6 +1283,10 @@ void QScxmlStateMachine::start()
     if (!parseErrors().isEmpty())
         return;
 
+    // Failure to initialize doesn't prevent start(). See w3c-ecma/test487 in the scion test suite.
+    if (!isInitialized() && !init())
+        qCDebug(qscxmlLog) << this << "cannot be initialized on start(). Starting anyway ...";
+
     d->m_qStateMachine->start();
 }
 
diff --git a/src/scxml/qscxmlstatemachine.h b/src/scxml/qscxmlstatemachine.h
index f1e7f82..0037fef 100644
--- a/src/scxml/qscxmlstatemachine.h
+++ b/src/scxml/qscxmlstatemachine.h
@@ -75,7 +75,9 @@ class Q_SCXML_EXPORT QScxmlStateMachine: public QObject
     Q_OBJECT
     Q_ENUMS(BindingMethod)
     Q_PROPERTY(bool running READ isRunning WRITE setRunning NOTIFY runningChanged)
+    Q_PROPERTY(bool initialized READ isInitialized NOTIFY initializedChanged)
     Q_PROPERTY(QScxmlDataModel *dataModel READ dataModel WRITE setDataModel NOTIFY dataModelChanged)
+    Q_PROPERTY(QVariantMap initialValues READ initialValues WRITE setInitialValues NOTIFY initialValuesChanged)
 
 protected:
 #ifndef Q_QDOC
@@ -98,17 +100,19 @@ public:
     static QString generateSessionId(const QString &prefix);
 
     bool isInvoked() const;
+    bool isInitialized() const;
 
     void setDataModel(QScxmlDataModel *model);
     QScxmlDataModel *dataModel() const;
 
     BindingMethod dataBinding() const;
 
-    bool init(const QVariantMap &initialDataValues = QVariantMap());
-
     bool isRunning() const;
     void setRunning(bool running);
 
+    QVariantMap initialValues();
+    void setInitialValues(const QVariantMap &initialValues);
+
     QString name() const;
     QStringList stateNames(bool compress = true) const;
     QStringList activeStateNames(bool compress = true) const;
@@ -135,10 +139,13 @@ Q_SIGNALS:
     void finished();
     void eventOccurred(const QScxmlEvent &event);
     void dataModelChanged(QScxmlDataModel *model);
+    void initialValuesChanged(const QVariantMap &initialValues);
+    void initializedChanged(bool initialized);
 
 public Q_SLOTS:
     void start();
     void stop();
+    bool init();
 
 protected: // methods for friends:
     friend QScxmlDataModel;
diff --git a/src/scxml/qscxmlstatemachine_p.h b/src/scxml/qscxmlstatemachine_p.h
index 5f2fff1..99334cf 100644
--- a/src/scxml/qscxmlstatemachine_p.h
+++ b/src/scxml/qscxmlstatemachine_p.h
@@ -139,6 +139,8 @@ public:
 public: // types & data fields:
     QString m_sessionId;
     bool m_isInvoked;
+    bool m_isInitialized;
+    QVariantMap m_initialValues;
     QScxmlDataModel *m_dataModel;
     QScxmlStateMachine::BindingMethod m_dataBinding;
     QScxmlExecutableContent::QScxmlExecutionEngine *m_executionEngine;