Drop the stateMachine parameter from data model constructors

Instead, make the data model a Q_PROPERTY of state machines. This makes
it much easier to independently instantiate state machines and data
models from QML and connect them via properties.

Change-Id: I62d712dd0ad7817c39432204ced431b8041e442d
Reviewed-by: Erik Verbruggen <erik.verbruggen@theqtcompany.com>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@theqtcompany.com>

13 files changed, 104 insertions, 54 deletions

diff --git a/src/scxml/qscxmlcppdatamodel.cpp b/src/scxml/qscxmlcppdatamodel.cpp
index be2fce8..9f00b75 100644
--- a/src/scxml/qscxmlcppdatamodel.cpp
+++ b/src/scxml/qscxmlcppdatamodel.cpp
@@ -128,10 +128,10 @@ void TheDataModel::evaluateToVoid(QScxmlExecutableContent::EvaluatorId id, bool
  */
 
 /*!
- * Creates a new C++ data model with the state machine \a stateMachine.
+ * Creates a new C++ data model with the parent object \a parent.
  */
-QScxmlCppDataModel::QScxmlCppDataModel(QScxmlStateMachine *stateMachine)
-    : QScxmlDataModel(*(new QScxmlCppDataModelPrivate(stateMachine)))
+QScxmlCppDataModel::QScxmlCppDataModel(QObject *parent)
+    : QScxmlDataModel(*(new QScxmlCppDataModelPrivate), parent)
 {}
 
 /*!
diff --git a/src/scxml/qscxmlcppdatamodel.h b/src/scxml/qscxmlcppdatamodel.h
index c6366e3..f6e344d 100644
--- a/src/scxml/qscxmlcppdatamodel.h
+++ b/src/scxml/qscxmlcppdatamodel.h
@@ -58,7 +58,7 @@ class Q_SCXML_EXPORT QScxmlCppDataModel: public QScxmlDataModel
     Q_OBJECT
     Q_DECLARE_PRIVATE(QScxmlCppDataModel)
 public:
-    QScxmlCppDataModel(QScxmlStateMachine *stateMachine);
+    QScxmlCppDataModel(QObject *parent = 0);
 
     bool setup(const QVariantMap &initialDataValues) Q_DECL_OVERRIDE;
 
diff --git a/src/scxml/qscxmlcppdatamodel_p.h b/src/scxml/qscxmlcppdatamodel_p.h
index 5a779e2..1712a73 100644
--- a/src/scxml/qscxmlcppdatamodel_p.h
+++ b/src/scxml/qscxmlcppdatamodel_p.h
@@ -60,8 +60,6 @@ QT_BEGIN_NAMESPACE
 class Q_SCXML_EXPORT QScxmlCppDataModelPrivate : public QScxmlDataModelPrivate
 {
 public:
-    QScxmlCppDataModelPrivate(QScxmlStateMachine *stateMachine) :
-        QScxmlDataModelPrivate(stateMachine) {}
     QScxmlEvent event;
 };
 
diff --git a/src/scxml/qscxmldatamodel.cpp b/src/scxml/qscxmldatamodel.cpp
index fd1ce9b..6e6d62b 100644
--- a/src/scxml/qscxmldatamodel.cpp
+++ b/src/scxml/qscxmldatamodel.cpp
@@ -69,21 +69,49 @@ QScxmlDataModel::ForeachLoopBody::~ForeachLoopBody()
  */
 
 /*!
- * Creates a new data model for the state machine \a stateMachine.
+  \property QScxmlDataModel::stateMachine
+
+  \brief The state machine this data model belongs to.
+
+  A data model can only belong to a single state machine and a state machine
+  can only have one data model. This relation needs to be set up before the
+  state machine is started. Setting this property on a data model will
+  automatically set the corresponding \c dataModel property on the
+  \a stateMachine.
+*/
+
+/*!
+ * Creates a new data model, with the parent object \a parent.
  */
-QScxmlDataModel::QScxmlDataModel(QScxmlStateMachine *stateMachine)
-    : QObject(*(new QScxmlDataModelPrivate(stateMachine)))
+QScxmlDataModel::QScxmlDataModel(QObject *parent)
+    : QObject(*(new QScxmlDataModelPrivate), parent)
 {
-    QScxmlStateMachinePrivate::get(stateMachine)->m_dataModel = this;
 }
 
 /*!
  * \internal
  */
-QScxmlDataModel::QScxmlDataModel(QScxmlDataModelPrivate &dd) :
-    QObject(dd)
+QScxmlDataModel::QScxmlDataModel(QScxmlDataModelPrivate &dd, QObject *parent) :
+    QObject(dd, parent)
 {
-    QScxmlStateMachinePrivate::get(dd.m_stateMachine)->m_dataModel = this;
+}
+
+/*!
+ * Sets the state machine this model belongs to to \a stateMachine. There is a
+ * 1:1 relation between state machines and models. After setting the state
+ * machine once you cannot change it anymore. Any further attempts to set the
+ * state machine using this method will be ignored.
+ */
+void QScxmlDataModel::setStateMachine(QScxmlStateMachine *stateMachine)
+{
+    Q_D(QScxmlDataModel);
+
+    if (d->m_stateMachine == Q_NULLPTR && stateMachine != Q_NULLPTR) {
+        d->m_stateMachine = stateMachine;
+        if (stateMachine)
+            stateMachine->setDataModel(this);
+        emit stateMachineChanged(stateMachine);
+    }
 }
 
 /*!
@@ -100,34 +128,25 @@ QScxmlTableData *QScxmlDataModel::tableData() const
     return stateMachine()->tableData();
 }
 
-QScxmlDataModel *QScxmlDataModelPrivate::instantiateDataModel(
-        DocumentModel::Scxml::DataModelType type, QScxmlStateMachine *stateMachine)
+QScxmlDataModel *QScxmlDataModelPrivate::instantiateDataModel(DocumentModel::Scxml::DataModelType type)
 {
-    Q_ASSERT(stateMachine);
-
     QScxmlDataModel *dataModel = Q_NULLPTR;
     switch (type) {
     case DocumentModel::Scxml::NullDataModel:
-        dataModel = new QScxmlNullDataModel(stateMachine);
+        dataModel = new QScxmlNullDataModel;
         break;
     case DocumentModel::Scxml::JSDataModel:
-        dataModel = new QScxmlEcmaScriptDataModel(stateMachine);
+        dataModel = new QScxmlEcmaScriptDataModel;
         break;
     case DocumentModel::Scxml::CppDataModel:
         break;
     default:
         Q_UNREACHABLE();
     }
-    QScxmlStateMachinePrivate::get(stateMachine)->parserData()->m_ownedDataModel.reset(dataModel);
 
     return dataModel;
 }
 
-void QScxmlDataModelPrivate::setStateMachine(QScxmlStateMachine *stateMachine)
-{
-    m_stateMachine = stateMachine;
-}
-
 /*!
  * \fn QScxmlDataModel::setup(const QVariantMap &initialDataValues)
  *
diff --git a/src/scxml/qscxmldatamodel.h b/src/scxml/qscxmldatamodel.h
index 79ae7c1..75c55e6 100644
--- a/src/scxml/qscxmldatamodel.h
+++ b/src/scxml/qscxmldatamodel.h
@@ -57,6 +57,7 @@ class Q_SCXML_EXPORT QScxmlDataModel : public QObject
 {
     Q_OBJECT
     Q_DECLARE_PRIVATE(QScxmlDataModel)
+    Q_PROPERTY(QScxmlStateMachine *stateMachine READ stateMachine WRITE setStateMachine NOTIFY stateMachineChanged)
 
 public:
     class ForeachLoopBody
@@ -67,8 +68,9 @@ public:
     };
 
 public:
-    QScxmlDataModel(QScxmlStateMachine *stateMachine);
+    QScxmlDataModel(QObject *parent = 0);
 
+    void setStateMachine(QScxmlStateMachine *stateMachine);
     QScxmlStateMachine *stateMachine() const;
 
     virtual bool setup(const QVariantMap &initialDataValues) = 0;
@@ -89,8 +91,11 @@ public:
     virtual bool hasScxmlProperty(const QString &name) const = 0;
     virtual bool setScxmlProperty(const QString &name, const QVariant &value, const QString &context) = 0;
 
+Q_SIGNALS:
+    void stateMachineChanged(QScxmlStateMachine *stateMachine);
+
 protected:
-    QScxmlDataModel(QScxmlDataModelPrivate &dd);
+    QScxmlDataModel(QScxmlDataModelPrivate &dd, QObject *parent = 0);
 #ifndef Q_QDOC
     QScxmlTableData *tableData() const;
 #endif // Q_QDOC
diff --git a/src/scxml/qscxmldatamodel_p.h b/src/scxml/qscxmldatamodel_p.h
index ee9e405..1fdcfbb 100644
--- a/src/scxml/qscxmldatamodel_p.h
+++ b/src/scxml/qscxmldatamodel_p.h
@@ -60,16 +60,9 @@ QT_BEGIN_NAMESPACE
 class QScxmlDataModelPrivate : public QObjectPrivate
 {
 public:
-    QScxmlDataModelPrivate(QScxmlStateMachine *stateMachine)
-        : m_stateMachine(stateMachine)
-    {
-        Q_ASSERT(stateMachine != Q_NULLPTR);
-    }
+    QScxmlDataModelPrivate() : m_stateMachine(Q_NULLPTR) {}
 
-    static QScxmlDataModel *instantiateDataModel(DocumentModel::Scxml::DataModelType type,
-                                                 QScxmlStateMachine *stateMachine);
-
-    void setStateMachine(QScxmlStateMachine *stateMachine);
+    static QScxmlDataModel *instantiateDataModel(DocumentModel::Scxml::DataModelType type);
 
 public:
     QScxmlStateMachine *m_stateMachine;
diff --git a/src/scxml/qscxmlecmascriptdatamodel.cpp b/src/scxml/qscxmlecmascriptdatamodel.cpp
index 91de2aa..54c2dfb 100644
--- a/src/scxml/qscxmlecmascriptdatamodel.cpp
+++ b/src/scxml/qscxmlecmascriptdatamodel.cpp
@@ -65,9 +65,8 @@ class QScxmlEcmaScriptDataModelPrivate : public QScxmlDataModelPrivate
 {
     Q_DECLARE_PUBLIC(QScxmlEcmaScriptDataModel)
 public:
-    QScxmlEcmaScriptDataModelPrivate(QScxmlStateMachine *stateMachine)
-        : QScxmlDataModelPrivate(stateMachine)
-        , jsEngine(Q_NULLPTR)
+    QScxmlEcmaScriptDataModelPrivate()
+        : jsEngine(Q_NULLPTR)
     {}
 
     QString evalStr(const QString &expr, const QString &context, bool *ok)
@@ -356,10 +355,10 @@ private:
  */
 
 /*!
- * Creates a new ECMAScript data model for the state machine \a stateMachine.
+ * Creates a new ECMAScript data model, with the parent object \a parent.
  */
-QScxmlEcmaScriptDataModel::QScxmlEcmaScriptDataModel(QScxmlStateMachine *stateMachine)
-    : QScxmlDataModel(*(new QScxmlEcmaScriptDataModelPrivate(stateMachine)))
+QScxmlEcmaScriptDataModel::QScxmlEcmaScriptDataModel(QObject *parent)
+    : QScxmlDataModel(*(new QScxmlEcmaScriptDataModelPrivate), parent)
 {}
 
 /*!
diff --git a/src/scxml/qscxmlecmascriptdatamodel.h b/src/scxml/qscxmlecmascriptdatamodel.h
index 37d62c8..0b0708c 100644
--- a/src/scxml/qscxmlecmascriptdatamodel.h
+++ b/src/scxml/qscxmlecmascriptdatamodel.h
@@ -51,7 +51,7 @@ class Q_SCXML_EXPORT QScxmlEcmaScriptDataModel: public QScxmlDataModel
     Q_OBJECT
     Q_DECLARE_PRIVATE(QScxmlEcmaScriptDataModel)
 public:
-    QScxmlEcmaScriptDataModel(QScxmlStateMachine *stateMachine);
+    QScxmlEcmaScriptDataModel(QObject *parent = 0);
 
     bool setup(const QVariantMap &initialDataValues) Q_DECL_OVERRIDE;
 
diff --git a/src/scxml/qscxmlnulldatamodel.cpp b/src/scxml/qscxmlnulldatamodel.cpp
index 754bc1a..c24a729 100644
--- a/src/scxml/qscxmlnulldatamodel.cpp
+++ b/src/scxml/qscxmlnulldatamodel.cpp
@@ -59,10 +59,6 @@ class QScxmlNullDataModelPrivate : public QScxmlDataModelPrivate
     };
 
 public:
-    QScxmlNullDataModelPrivate(QScxmlStateMachine *stateMachine)
-        : QScxmlDataModelPrivate(stateMachine)
-    {}
-
     bool evalBool(QScxmlExecutableContent::EvaluatorId id, bool *ok)
     {
         Q_Q(QScxmlNullDataModel);
@@ -132,10 +128,10 @@ private:
  */
 
 /*!
- * Creates a new Qt SCXML data model for the state machine \a stateMachine.
+ * Creates a new Qt SCXML data model, with the parent object \a parent.
  */
-QScxmlNullDataModel::QScxmlNullDataModel(QScxmlStateMachine *stateMachine)
-    : QScxmlDataModel(*(new QScxmlNullDataModelPrivate(stateMachine)))
+QScxmlNullDataModel::QScxmlNullDataModel(QObject *parent)
+    : QScxmlDataModel(*(new QScxmlNullDataModelPrivate), parent)
 {}
 
 /*!
diff --git a/src/scxml/qscxmlnulldatamodel.h b/src/scxml/qscxmlnulldatamodel.h
index 9f75db7..5fb28d9 100644
--- a/src/scxml/qscxmlnulldatamodel.h
+++ b/src/scxml/qscxmlnulldatamodel.h
@@ -50,7 +50,7 @@ class Q_SCXML_EXPORT QScxmlNullDataModel: public QScxmlDataModel
     Q_OBJECT
     Q_DECLARE_PRIVATE(QScxmlNullDataModel)
 public:
-    QScxmlNullDataModel(QScxmlStateMachine *stateMachine);
+    QScxmlNullDataModel(QObject *parent = 0);
 
     bool setup(const QVariantMap &initialDataValues) Q_DECL_OVERRIDE;
 
diff --git a/src/scxml/qscxmlparser.cpp b/src/scxml/qscxmlparser.cpp
index 6a91142..162b6a2 100644
--- a/src/scxml/qscxmlparser.cpp
+++ b/src/scxml/qscxmlparser.cpp
@@ -1007,7 +1007,9 @@ inline QScxmlInvokableService *InvokeDynamicScxmlFactory::invoke(QScxmlStateMach
 {
     auto child = QStateMachineBuilder().build(m_content.data());
 
-    QScxmlDataModelPrivate::instantiateDataModel(m_content->root->dataModel, child);
+    auto dm = QScxmlDataModelPrivate::instantiateDataModel(m_content->root->dataModel);
+    dm->setParent(child);
+    child->setDataModel(dm);
 
     return finishInvoke(child, parent);
 }
@@ -1148,8 +1150,9 @@ void QScxmlParser::instantiateDataModel(QScxmlStateMachine *stateMachine) const
     if (root == Q_NULLPTR) {
         qWarning() << "SCXML document has no root element";
     } else {
-        QScxmlDataModel *dm = QScxmlDataModelPrivate::instantiateDataModel(root->dataModel,
-                                                                           stateMachine);
+        QScxmlDataModel *dm = QScxmlDataModelPrivate::instantiateDataModel(root->dataModel);
+        QScxmlStateMachinePrivate::get(stateMachine)->parserData()->m_ownedDataModel.reset(dm);
+        stateMachine->setDataModel(dm);
         if (dm == Q_NULLPTR)
             qWarning() << "No data-model instantiated";
     }
diff --git a/src/scxml/qscxmlstatemachine.cpp b/src/scxml/qscxmlstatemachine.cpp
index 1939fcc..eeca441 100644
--- a/src/scxml/qscxmlstatemachine.cpp
+++ b/src/scxml/qscxmlstatemachine.cpp
@@ -456,6 +456,22 @@ QScxmlStateMachine::QScxmlStateMachine(QScxmlStateMachinePrivate &dd, QObject *p
  */
 
 /*!
+    \property QScxmlStateMachine::dataModel
+
+    \brief The data model to be used for this state machine.
+
+    SCXML data models are described in
+    \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.
+
+    \sa QScxmlDataModel, QScxmlNullDataModel, QScxmlEcmaScriptDataModel,
+        QScxmlCppDataModel
+*/
+
+/*!
     \enum QScxmlStateMachine::BindingMethod
 
     This enum specifies the binding method. The binding method controls the point in time
@@ -520,6 +536,24 @@ bool QScxmlStateMachine::isInvoked() const
 }
 
 /*!
+ * 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
+ * cannot change it anymore. Any further attempts to set the model using this
+ * method will be ignored.
+ */
+void QScxmlStateMachine::setDataModel(QScxmlDataModel *model)
+{
+    Q_D(QScxmlStateMachine);
+
+    if (d->m_dataModel == Q_NULLPTR && model != Q_NULLPTR) {
+        d->m_dataModel = model;
+        if (model)
+            model->setStateMachine(this);
+        emit dataModelChanged(model);
+    }
+}
+
+/*!
  * Returns the data model used by the state machine.
  */
 QScxmlDataModel *QScxmlStateMachine::dataModel() const
diff --git a/src/scxml/qscxmlstatemachine.h b/src/scxml/qscxmlstatemachine.h
index 0f7aeed..f1e7f82 100644
--- a/src/scxml/qscxmlstatemachine.h
+++ b/src/scxml/qscxmlstatemachine.h
@@ -75,6 +75,7 @@ class Q_SCXML_EXPORT QScxmlStateMachine: public QObject
     Q_OBJECT
     Q_ENUMS(BindingMethod)
     Q_PROPERTY(bool running READ isRunning WRITE setRunning NOTIFY runningChanged)
+    Q_PROPERTY(QScxmlDataModel *dataModel READ dataModel WRITE setDataModel NOTIFY dataModelChanged)
 
 protected:
 #ifndef Q_QDOC
@@ -98,6 +99,7 @@ public:
 
     bool isInvoked() const;
 
+    void setDataModel(QScxmlDataModel *model);
     QScxmlDataModel *dataModel() const;
 
     BindingMethod dataBinding() const;
@@ -132,6 +134,7 @@ Q_SIGNALS:
     void reachedStableState();
     void finished();
     void eventOccurred(const QScxmlEvent &event);
+    void dataModelChanged(QScxmlDataModel *model);
 
 public Q_SLOTS:
     void start();