Unwrap QJSValue from QVariant in QV8Engine::fromVariant

When QML tries to unwrap real value from a QVariant and
the value is a QJSValue instance, then no conversion is needed,
QJSValue already contains a v8 handle.

This patch, for example, solves a problem of emitting QJSValue
instance in a signal that has QVariant as an argument. The QJSValue
can be unwrapped and used as a normal JS value in a connected slot.
This feature may be used also in a plugin model that stores QJSValues
internally. Then the model in data() function can return a QJSValue
which would be understood by QML.

Change-Id: I1d5ede40ce2637123b09839fd848b27ad3af3dda
Reviewed-on: http://codereview.qt-project.org/4451
Reviewed-by: Kent Hansen <kent.hansen@nokia.com>
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>

3 files changed, 88 insertions, 0 deletions

diff --git a/tests/auto/declarative/qdeclarativeecmascript/data/signalWithJSValueInVariant.qml b/tests/auto/declarative/qdeclarativeecmascript/data/signalWithJSValueInVariant.qml
new file mode 100644
index 0000000000..a6f1aa381a
--- /dev/null
+++ b/tests/auto/declarative/qdeclarativeecmascript/data/signalWithJSValueInVariant.qml
@@ -0,0 +1,12 @@
+import Qt.test 1.0
+
+MyQmlObject {
+    property string expression
+    property string compare
+    property bool pass: false
+    onSignalWithVariant:
+    {
+        var expected = eval(expression);
+        pass = eval(compare)(arg, expected);
+    }
+}
diff --git a/tests/auto/declarative/qdeclarativeecmascript/testtypes.h b/tests/auto/declarative/qdeclarativeecmascript/testtypes.h
index 52b74affa8..ebe8cc59b7 100644
--- a/tests/auto/declarative/qdeclarativeecmascript/testtypes.h
+++ b/tests/auto/declarative/qdeclarativeecmascript/testtypes.h
@@ -170,6 +170,7 @@ signals:
     void anotherBasicSignal();
     void thirdBasicSignal();
     void signalWithUnknownType(const MyQmlObject::MyType &arg);
+    void signalWithVariant(const QVariant &arg);
 
 public slots:
     void deleteMe() { delete this; }
diff --git a/tests/auto/declarative/qdeclarativeecmascript/tst_qdeclarativeecmascript.cpp b/tests/auto/declarative/qdeclarativeecmascript/tst_qdeclarativeecmascript.cpp
index 36941afc89..941765d50c 100644
--- a/tests/auto/declarative/qdeclarativeecmascript/tst_qdeclarativeecmascript.cpp
+++ b/tests/auto/declarative/qdeclarativeecmascript/tst_qdeclarativeecmascript.cpp
@@ -146,6 +146,10 @@ private slots:
     void numberAssignment();
     void propertySplicing();
     void signalWithUnknownTypes();
+    void signalWithJSValueInVariant_data();
+    void signalWithJSValueInVariant();
+    void signalWithJSValueInVariant_twoEngines_data();
+    void signalWithJSValueInVariant_twoEngines();
     void moduleApi_data();
     void moduleApi();
     void importScripts();
@@ -2758,6 +2762,77 @@ void tst_qdeclarativeecmascript::signalWithUnknownTypes()
     delete object;
 }
 
+void tst_qdeclarativeecmascript::signalWithJSValueInVariant_data()
+{
+    QTest::addColumn<QString>("expression");
+    QTest::addColumn<QString>("compare");
+
+    QString compareStrict("(function(a, b) { return a === b; })");
+    QTest::newRow("true") << "true" << compareStrict;
+    QTest::newRow("undefined") << "undefined" << compareStrict;
+    QTest::newRow("null") << "null" << compareStrict;
+    QTest::newRow("123") << "123" << compareStrict;
+    QTest::newRow("'ciao'") << "'ciao'" << compareStrict;
+
+    QString comparePropertiesStrict(
+        "(function(a, b) {"
+        "  if (typeof b != 'object')"
+        "    return a === b;"
+        "  var props = Object.getOwnPropertyNames(b);"
+        "  for (var i = 0; i < props.length; ++i) {"
+        "    var p = props[i];"
+        "    return arguments.callee(a[p], b[p]);"
+        "  }"
+        "})");
+    QTest::newRow("{ foo: 'bar' }") << "({ foo: 'bar' })"  << comparePropertiesStrict;
+    QTest::newRow("[10,20,30]") << "[10,20,30]"  << comparePropertiesStrict;
+}
+
+void tst_qdeclarativeecmascript::signalWithJSValueInVariant()
+{
+    QFETCH(QString, expression);
+    QFETCH(QString, compare);
+
+    QDeclarativeComponent component(&engine, TEST_FILE("signalWithJSValueInVariant.qml"));
+    QScopedPointer<MyQmlObject> object(qobject_cast<MyQmlObject *>(component.create()));
+    QVERIFY(object != 0);
+
+    QJSValue value = engine.evaluate(expression);
+    QVERIFY(!engine.hasUncaughtException());
+    object->setProperty("expression", expression);
+    object->setProperty("compare", compare);
+    object->setProperty("pass", false);
+
+    emit object->signalWithVariant(QVariant::fromValue(value));
+    QVERIFY(object->property("pass").toBool());
+}
+
+void tst_qdeclarativeecmascript::signalWithJSValueInVariant_twoEngines_data()
+{
+    signalWithJSValueInVariant_data();
+}
+
+void tst_qdeclarativeecmascript::signalWithJSValueInVariant_twoEngines()
+{
+    QFETCH(QString, expression);
+    QFETCH(QString, compare);
+
+    QDeclarativeComponent component(&engine, TEST_FILE("signalWithJSValueInVariant.qml"));
+    QScopedPointer<MyQmlObject> object(qobject_cast<MyQmlObject *>(component.create()));
+    QVERIFY(object != 0);
+
+    QJSEngine engine2;
+    QJSValue value = engine2.evaluate(expression);
+    QVERIFY(!engine2.hasUncaughtException());
+    object->setProperty("expression", expression);
+    object->setProperty("compare", compare);
+    object->setProperty("pass", false);
+
+    QTest::ignoreMessage(QtWarningMsg, "JSValue can't be rassigned to an another engine.");
+    emit object->signalWithVariant(QVariant::fromValue(value));
+    QVERIFY(!object->property("pass").toBool());
+}
+
 void tst_qdeclarativeecmascript::moduleApi_data()
 {
     QTest::addColumn<QUrl>("testfile");