Fix mapping of JS objects/arrays to C++

[ChangeLog][QtQml][Important Behavior Changes] When a JavaScript object/array
is passed to C++ through a QVariant, the engine no longer immediately converts
the object recursively into a QVariantMap or QVariantList but instead stores
a QJSValue in the QVariant. This prevents a loss of data when the JS object
contains non-primitive types such as function objects for example. Code that
expects the variant type to be exactly QVariant::Map or QVariant::List may
need to be adapted. Registered conversion functions however ensure that code
that merely calls toMap() or toList() continues to work.

Task-number: QTBUG-40431
Change-Id: I1dbc1d5f8e78ad28bb62db3681b9a0b34557e7f5
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

3 files changed, 72 insertions, 31 deletions

diff --git a/src/qml/jsapi/qjsengine.cpp b/src/qml/jsapi/qjsengine.cpp
index 58251fac96..0d2b394cd6 100644
--- a/src/qml/jsapi/qjsengine.cpp
+++ b/src/qml/jsapi/qjsengine.cpp
@@ -420,17 +420,19 @@ bool QJSEngine::convertV2(const QJSValue &value, int type, void *ptr)
         QV4::ScopedValue v(scope, vp->getValue(engine->m_v4Engine));
         return engine->metaTypeFromJS(v, type, ptr);
     } else if (vp->value.isEmpty()) {
-        // have a string based value without engine. Do conversion manually
-        if (type == QMetaType::Bool) {
-            *reinterpret_cast<bool*>(ptr) = vp->string.length() != 0;
-            return true;
-        }
-        if (type == QMetaType::QString) {
-            *reinterpret_cast<QString*>(ptr) = vp->string;
-            return true;
-        }
-        double d = QV4::RuntimeHelpers::stringToNumber(vp->string);
-        switch (type) {
+        if (vp->unboundData.userType() == QMetaType::QString) {
+            QString string = vp->unboundData.toString();
+            // have a string based value without engine. Do conversion manually
+            if (type == QMetaType::Bool) {
+                *reinterpret_cast<bool*>(ptr) = string.length() != 0;
+                return true;
+            }
+            if (type == QMetaType::QString) {
+                *reinterpret_cast<QString*>(ptr) = string;
+                return true;
+            }
+            double d = QV4::RuntimeHelpers::stringToNumber(string);
+            switch (type) {
             case QMetaType::Int:
                 *reinterpret_cast<int*>(ptr) = QV4::Primitive::toInt32(d);
                 return true;
@@ -466,6 +468,9 @@ bool QJSEngine::convertV2(const QJSValue &value, int type, void *ptr)
                 return true;
             default:
                 return false;
+            }
+        } else {
+            return QMetaType::convert(&vp->unboundData.data_ptr(), vp->unboundData.userType(), ptr, type);
         }
     } else {
         switch (type) {
diff --git a/src/qml/jsapi/qjsvalue.cpp b/src/qml/jsapi/qjsvalue.cpp
index 891f17762c..47a764e641 100644
--- a/src/qml/jsapi/qjsvalue.cpp
+++ b/src/qml/jsapi/qjsvalue.cpp
@@ -58,14 +58,14 @@ QV4::ReturnedValue QJSValuePrivate::getValue(QV4::ExecutionEngine *e)
     }
 
     if (value.isEmpty()) {
-        value = QV4::Encode(engine->newString(string));
+        value = QV4::Encode(engine->v8Engine->fromVariant(unboundData));
         PersistentValuePrivate **listRoot = &engine->memoryManager->m_persistentValues;
         prev = listRoot;
         next = *listRoot;
         *prev = this;
         if (next)
             next->prev = &this->next;
-        string = QString();
+        unboundData.clear();
     }
     return value.asReturnedValue();
 }
@@ -353,8 +353,21 @@ bool QJSValue::isVariant() const
 */
 QString QJSValue::toString() const
 {
-    if (d->value.isEmpty())
-        return d->string;
+    if (d->value.isEmpty()) {
+        if (d->unboundData.type() == QVariant::Map)
+            return QStringLiteral("[object Object]");
+        else if (d->unboundData.type() == QVariant::List) {
+            const QVariantList list = d->unboundData.toList();
+            QString result;
+            for (int i = 0; i < list.count(); ++i) {
+                if (i > 0)
+                    result.append(QLatin1Char(','));
+                result.append(list.at(i).toString());
+            }
+            return result;
+        }
+        return d->unboundData.toString();
+    }
     return d->value.toQStringNoThrow();
 }
 
@@ -372,8 +385,14 @@ QString QJSValue::toString() const
 */
 double QJSValue::toNumber() const
 {
-    if (d->value.isEmpty())
-        return RuntimeHelpers::stringToNumber(d->string);
+    if (d->value.isEmpty()) {
+        if (d->unboundData.type() == QVariant::String)
+            return RuntimeHelpers::stringToNumber(d->unboundData.toString());
+        else if (d->unboundData.canConvert<double>())
+            return d->unboundData.value<double>();
+        else
+            return std::numeric_limits<double>::quiet_NaN();
+    }
 
     QV4::ExecutionContext *ctx = d->engine ? d->engine->currentContext() : 0;
     double dbl = d->value.toNumber();
@@ -398,8 +417,12 @@ double QJSValue::toNumber() const
 */
 bool QJSValue::toBool() const
 {
-    if (d->value.isEmpty())
-        return d->string.length() > 0;
+    if (d->value.isEmpty()) {
+        if (d->unboundData.userType() == QMetaType::QString)
+            return d->unboundData.toString().length() > 0;
+        else
+            return d->unboundData.toBool();
+    }
 
     QV4::ExecutionContext *ctx = d->engine ? d->engine->currentContext() : 0;
     bool b = d->value.toBoolean();
@@ -424,8 +447,12 @@ bool QJSValue::toBool() const
 */
 qint32 QJSValue::toInt() const
 {
-    if (d->value.isEmpty())
-        return QV4::Primitive::toInt32(RuntimeHelpers::stringToNumber(d->string));
+    if (d->value.isEmpty()) {
+        if (d->unboundData.userType() == QMetaType::QString)
+            return QV4::Primitive::toInt32(RuntimeHelpers::stringToNumber(d->unboundData.toString()));
+        else
+            return d->unboundData.toInt();
+    }
 
     QV4::ExecutionContext *ctx = d->engine ? d->engine->currentContext() : 0;
     qint32 i = d->value.toInt32();
@@ -450,8 +477,12 @@ qint32 QJSValue::toInt() const
 */
 quint32 QJSValue::toUInt() const
 {
-    if (d->value.isEmpty())
-        return QV4::Primitive::toUInt32(RuntimeHelpers::stringToNumber(d->string));
+    if (d->value.isEmpty()) {
+        if (d->unboundData.userType() == QMetaType::QString)
+            return QV4::Primitive::toUInt32(RuntimeHelpers::stringToNumber(d->unboundData.toString()));
+        else
+            return d->unboundData.toUInt();
+    }
 
     QV4::ExecutionContext *ctx = d->engine ? d->engine->currentContext() : 0;
     quint32 u = d->value.toUInt32();
@@ -487,7 +518,7 @@ quint32 QJSValue::toUInt() const
 QVariant QJSValue::toVariant() const
 {
     if (d->value.isEmpty())
-        return QVariant(d->string);
+        return d->unboundData;
 
     return QV4::VariantObject::toVariant(d->value);
 }
@@ -775,8 +806,10 @@ bool QJSValue::equals(const QJSValue& other) const
 {
     if (d->value.isEmpty()) {
         if (other.d->value.isEmpty())
-            return d->string == other.d->string;
-        return js_equal(d->string, QV4::ValueRef(other.d->value));
+            return d->unboundData == other.d->unboundData;
+        if (d->unboundData.type() == QVariant::Map || d->unboundData.type() == QVariant::List)
+            return false;
+        return js_equal(d->unboundData.toString(), QV4::ValueRef(other.d->value));
     }
     if (other.d->value.isEmpty())
         return other.equals(*this);
@@ -810,9 +843,11 @@ bool QJSValue::strictlyEquals(const QJSValue& other) const
 {
     if (d->value.isEmpty()) {
         if (other.d->value.isEmpty())
-            return d->string == other.d->string;
+            return d->unboundData == other.d->unboundData;
+        if (d->unboundData.type() == QVariant::Map || d->unboundData.type() == QVariant::List)
+            return false;
         if (other.d->value.isString())
-            return d->string == other.d->value.stringValue()->toQString();
+            return d->unboundData.toString() == other.d->value.stringValue()->toQString();
         return false;
     }
     if (other.d->value.isEmpty())
diff --git a/src/qml/jsapi/qjsvalue_p.h b/src/qml/jsapi/qjsvalue_p.h
index e66c1bcde4..43a3a74e38 100644
--- a/src/qml/jsapi/qjsvalue_p.h
+++ b/src/qml/jsapi/qjsvalue_p.h
@@ -51,6 +51,7 @@
 #include <private/qv4string_p.h>
 #include <private/qv4engine_p.h>
 #include <private/qv4object_p.h>
+#include <private/qflagpointer_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -72,8 +73,8 @@ public:
         Q_ASSERT(!value.isEmpty());
     }
     QJSValuePrivate(const QString &s)
-        : PersistentValuePrivate(QV4::Primitive::emptyValue().asReturnedValue())
-        , string(s)
+        : PersistentValuePrivate(QV4::Primitive::emptyValue().asReturnedValue()),
+          unboundData(s)
     {
     }
 
@@ -81,7 +82,7 @@ public:
 
     static QJSValuePrivate *get(const QJSValue &v) { return v.d; }
 
-    QString string;
+    QVariant unboundData;
 };
 
 QT_END_NAMESPACE