Don't crash when trying to execute things in the null data model

Rather raise error.execution, as mandated by the standard (in most of
those cases).

Change-Id: If2e200693198b70b4bf067011318f0d78c44653b
Reviewed-by: Jarek Kobus <jaroslaw.kobus@theqtcompany.com>

4 files changed, 37 insertions, 11 deletions

diff --git a/src/scxml/qscxmlnulldatamodel.cpp b/src/scxml/qscxmlnulldatamodel.cpp
index c888708..a2d8a14 100644
--- a/src/scxml/qscxmlnulldatamodel.cpp
+++ b/src/scxml/qscxmlnulldatamodel.cpp
@@ -164,38 +164,48 @@ bool QScxmlNullDataModel::evaluateToBool(QScxmlExecutableContent::EvaluatorId id
 QVariant QScxmlNullDataModel::evaluateToVariant(QScxmlExecutableContent::EvaluatorId id, bool *ok)
 {
     Q_UNUSED(id);
-    Q_UNUSED(ok);
-    Q_UNREACHABLE();
+    *ok = false;
+    QScxmlStateMachinePrivate::get(stateMachine())->submitError(
+                QStringLiteral("error.execution"),
+                QStringLiteral("Cannot evaluate expressions on a null data model"));
     return QVariant();
 }
 
 void QScxmlNullDataModel::evaluateToVoid(QScxmlExecutableContent::EvaluatorId id, bool *ok)
 {
     Q_UNUSED(id);
-    Q_UNUSED(ok);
-    Q_UNREACHABLE();
+    *ok = false;
+    QScxmlStateMachinePrivate::get(stateMachine())->submitError(
+                QStringLiteral("error.execution"),
+                QStringLiteral("Cannot evaluate expressions on a null data model"));
 }
 
 void QScxmlNullDataModel::evaluateAssignment(QScxmlExecutableContent::EvaluatorId id, bool *ok)
 {
     Q_UNUSED(id);
-    Q_UNUSED(ok);
-    Q_UNREACHABLE();
+    *ok = false;
+    QScxmlStateMachinePrivate::get(stateMachine())->submitError(
+                QStringLiteral("error.execution"),
+                QStringLiteral("Cannot assign values on a null data model"));
 }
 
 void QScxmlNullDataModel::evaluateInitialization(QScxmlExecutableContent::EvaluatorId id, bool *ok)
 {
     Q_UNUSED(id);
-    Q_UNUSED(ok);
-    Q_UNREACHABLE();
+    *ok = false;
+    QScxmlStateMachinePrivate::get(stateMachine())->submitError(
+                QStringLiteral("error.execution"),
+                QStringLiteral("Cannot initialize values on a null data model"));
 }
 
 bool QScxmlNullDataModel::evaluateForeach(QScxmlExecutableContent::EvaluatorId id, bool *ok, ForeachLoopBody *body)
 {
     Q_UNUSED(id);
-    Q_UNUSED(ok);
     Q_UNUSED(body);
-    Q_UNREACHABLE();
+    *ok = false;
+    QScxmlStateMachinePrivate::get(stateMachine())->submitError(
+                QStringLiteral("error.execution"),
+                QStringLiteral("Cannot run foreach on a null data model"));
     return false;
 }
 
diff --git a/tests/auto/compiled/compiled.pro b/tests/auto/compiled/compiled.pro
index 7dc62ba..53dcd8c 100644
--- a/tests/auto/compiled/compiled.pro
+++ b/tests/auto/compiled/compiled.pro
@@ -16,6 +16,7 @@ STATECHARTS = \
     eventnames2.scxml \
     statemachineunicodename.scxml \
     anonymousstate.scxml \
-    submachineunicodename.scxml
+    submachineunicodename.scxml \
+    datainnulldatamodel.scxml
 
 load(qscxmlc)
diff --git a/tests/auto/compiled/datainnulldatamodel.scxml b/tests/auto/compiled/datainnulldatamodel.scxml
new file mode 100644
index 0000000..c8cc7fb
--- /dev/null
+++ b/tests/auto/compiled/datainnulldatamodel.scxml
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<scxml name="DataInNullDataModel" xmlns="http://www.w3.org/2005/07/scxml" version="1.0" initial="a">
+    <datamodel>
+        <data id="x" expr="2"/>
+    </datamodel>
+    <state id="a"></state>
+</scxml>
diff --git a/tests/auto/compiled/tst_compiled.cpp b/tests/auto/compiled/tst_compiled.cpp
index 9c4c1e4..ca9b7b3 100644
--- a/tests/auto/compiled/tst_compiled.cpp
+++ b/tests/auto/compiled/tst_compiled.cpp
@@ -33,6 +33,7 @@
 #include <QtScxml/qscxmlstatemachine.h>
 #include "ids1.h"
 #include "statemachineunicodename.h"
+#include "datainnulldatamodel.h"
 
 Q_DECLARE_METATYPE(QScxmlError);
 
@@ -44,6 +45,7 @@ class tst_Compiled: public QObject
 
 private Q_SLOTS:
     void stateNames();
+    void nullDataInit();
 };
 
 void tst_Compiled::stateNames()
@@ -81,6 +83,12 @@ void tst_Compiled::stateNames()
     QCOMPARE(stateMachine3.stateNames(false), calculatorStates);
 }
 
+void tst_Compiled::nullDataInit()
+{
+    DataInNullDataModel nullData;
+    QVERIFY(!nullData.init()); // raises an error, but doesn't crash
+}
+
 QTEST_MAIN(tst_Compiled)
 
 #include "tst_compiled.moc"