4 files changed, 82 insertions, 0 deletions

diff --git a/src/qml/jsapi/qjsvalue.cpp b/src/qml/jsapi/qjsvalue.cpp
index 5525aee595..6d70c72722 100644
--- a/src/qml/jsapi/qjsvalue.cpp
+++ b/src/qml/jsapi/qjsvalue.cpp
@@ -633,6 +633,39 @@ QVariant QJSValue::toVariant(QJSValue::ObjectConversionBehavior behavior) const
 }
 
 /*!
+ * Converts the value to a QJSPrimitiveValue. If the value holds a type
+ * supported by QJSPrimitiveValue, the value is copied. Otherwise the
+ * value is converted to a string, and the string is stored in
+ * QJSPrimitiveValue.
+ *
+ * \note Conversion of a managed value to a string can throw an exception. In
+ *       particular, symbols cannot be coerced into strings, or a custom
+ *       toString() method  may throw. In this case the result is the undefined
+ *       value and the engine carries an error after the conversion.
+ */
+QJSPrimitiveValue QJSValue::toPrimitive() const
+{
+    if (const QString *string = QJSValuePrivate::asQString(this))
+        return *string;
+
+    const QV4::Value val = QV4::Value::fromReturnedValue(QJSValuePrivate::asReturnedValue(this));
+    if (val.isUndefined())
+        return QJSPrimitiveUndefined();
+    if (val.isNull())
+        return QJSPrimitiveNull();
+    if (val.isBoolean())
+        return val.toBoolean();
+    if (val.isInteger())
+        return val.integerValue();
+    if (val.isDouble())
+        return val.doubleValue();
+
+    bool ok;
+    const QString result = val.toQString(&ok);
+    return ok ? QJSPrimitiveValue(result) : QJSPrimitiveValue(QJSPrimitiveUndefined());
+}
+
+/*!
   Calls this QJSValue as a function, passing \a args as arguments
   to the function, and using the globalObject() as the "this"-object.
   Returns the value returned from the function.
diff --git a/src/qml/jsapi/qjsvalue.h b/src/qml/jsapi/qjsvalue.h
index 3f8a16a149..1844ed0989 100644
--- a/src/qml/jsapi/qjsvalue.h
+++ b/src/qml/jsapi/qjsvalue.h
@@ -136,6 +136,7 @@ public:
 
     QVariant toVariant() const;
     QVariant toVariant(ObjectConversionBehavior behavior) const;
+    QJSPrimitiveValue toPrimitive() const;
 
     QObject *toQObject() const;
     const QMetaObject *toQMetaObject() const;
diff --git a/tests/auto/qml/qjsvalue/tst_qjsvalue.cpp b/tests/auto/qml/qjsvalue/tst_qjsvalue.cpp
index e2f83a78ba..fd2eb40717 100644
--- a/tests/auto/qml/qjsvalue/tst_qjsvalue.cpp
+++ b/tests/auto/qml/qjsvalue/tst_qjsvalue.cpp
@@ -1149,6 +1149,52 @@ void tst_QJSValue::toVariant()
     }
 }
 
+void tst_QJSValue::toPrimitive_data()
+{
+    newEngine();
+    QTest::addColumn<QJSValue>("value");
+    QTest::addColumn<QJSPrimitiveValue>("result");
+    QTest::addColumn<bool>("causesError");
+
+    QTest::newRow("undefined")       << QJSValue(QJSValue::UndefinedValue)
+                                     << QJSPrimitiveValue(QJSPrimitiveUndefined()) << false;
+    QTest::newRow("null")            << QJSValue(QJSValue::NullValue)
+                                     << QJSPrimitiveValue(QJSPrimitiveNull()) << false;
+    QTest::newRow("bool(true)")      << QJSValue(true) << QJSPrimitiveValue(true) << false;
+    QTest::newRow("bool(false)")     << QJSValue(false) << QJSPrimitiveValue(false) << false;
+    QTest::newRow("int")             << QJSValue(123) << QJSPrimitiveValue(123) << false;
+    QTest::newRow("double")          << QJSValue(10.2) << QJSPrimitiveValue(10.2) << false;
+    QTest::newRow("string")          << QJSValue(QStringLiteral("boo"))
+                                     << QJSPrimitiveValue(QStringLiteral("boo")) << false;
+    QTest::newRow("string(managed)") << engine->toScriptValue(QStringLiteral("mmmm"))
+                                     << QJSPrimitiveValue(QStringLiteral("mmmm")) << false;
+    QTest::newRow("symbol")          << engine->evaluate(QStringLiteral("Symbol('bar')"))
+                                     << QJSPrimitiveValue(QJSPrimitiveUndefined()) << true;
+    QTest::newRow("throws")          << engine->evaluate(QStringLiteral(
+                                                             "var a = {};\n"
+                                                             "a.__proto__.toString = function() {\n"
+                                                             "    throw new Error('naeh!');\n"
+                                                             "};\n"
+                                                             "a;"))
+                                     << QJSPrimitiveValue(QJSPrimitiveUndefined()) << true;
+}
+
+void tst_QJSValue::toPrimitive()
+{
+    QFETCH(QJSValue, value);
+    QFETCH(QJSPrimitiveValue, result);
+    QFETCH(bool, causesError);
+
+    QCOMPARE(value.toPrimitive(), result);
+    if (causesError) {
+        QVERIFY(engine->hasError());
+        engine->catchError();
+    } else {
+        QJSValue reconstructed(std::move(result));
+        QVERIFY(reconstructed.strictlyEquals(value));
+    }
+}
+
 void tst_QJSValue::toQObject_nonQObject_data()
 {
     newEngine();
diff --git a/tests/auto/qml/qjsvalue/tst_qjsvalue.h b/tests/auto/qml/qjsvalue/tst_qjsvalue.h
index a291e156e0..0b35b58c58 100644
--- a/tests/auto/qml/qjsvalue/tst_qjsvalue.h
+++ b/tests/auto/qml/qjsvalue/tst_qjsvalue.h
@@ -69,6 +69,8 @@ private slots:
     void toInt();
     void toUInt();
     void toVariant();
+    void toPrimitive_data();
+    void toPrimitive();
     void toQObject_nonQObject_data();
     void toQObject_nonQObject();
     void toQObject();