QJson*: value semantics cleanup

Re-add the move operations, add a swap(), mark as shared
(we're already using them in containers).

QJsonValue is slightly tricky, because it has an anonymous union,
which can't be easily moved in C++. Use the implementation of
the copy constructor as inspiration for the move.

[ChangeLog][QtCore][JSON] QJsonArray, QJsonDocument, QJsonObject
and QJsonValue now have move operations and a swap() member function.

Change-Id: Idfb94a93370ace96100efbd6559ef05b4c5adc39
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/src/corelib/json/qjsonobject.h b/src/corelib/json/qjsonobject.h
index e238c84d98..c77e2164a8 100644
--- a/src/corelib/json/qjsonobject.h
+++ b/src/corelib/json/qjsonobject.h
@@ -74,6 +74,25 @@ public:
     QJsonObject(const QJsonObject &other);
     QJsonObject &operator =(const QJsonObject &other);
 
+    QJsonObject(QJsonObject &&other) Q_DECL_NOTHROW
+        : d(other.d), o(other.o)
+    {
+        other.d = nullptr;
+        other.o = nullptr;
+    }
+
+    QJsonObject &operator =(QJsonObject &&other) Q_DECL_NOTHROW
+    {
+        swap(other);
+        return *this;
+    }
+
+    void swap(QJsonObject &other) Q_DECL_NOTHROW
+    {
+        qSwap(d, other.d);
+        qSwap(o, other.o);
+    }
+
     static QJsonObject fromVariantMap(const QVariantMap &map);
     QVariantMap toVariantMap() const;
     static QJsonObject fromVariantHash(const QVariantHash &map);
@@ -241,6 +260,8 @@ private:
     QJsonPrivate::Object *o;
 };
 
+Q_DECLARE_SHARED_NOT_MOVABLE_UNTIL_QT6(QJsonObject)
+
 #if !defined(QT_NO_DEBUG_STREAM) && !defined(QT_JSON_READONLY)
 Q_CORE_EXPORT QDebug operator<<(QDebug, const QJsonObject &);
 #endif