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, 22 insertions, 0 deletions

diff --git a/src/corelib/json/qjsonarray.h b/src/corelib/json/qjsonarray.h
index 3b6fa37cfa..ddba2ca78e 100644
--- a/src/corelib/json/qjsonarray.h
+++ b/src/corelib/json/qjsonarray.h
@@ -72,6 +72,20 @@ public:
     QJsonArray(const QJsonArray &other);
     QJsonArray &operator =(const QJsonArray &other);
 
+    QJsonArray(QJsonArray &&other) Q_DECL_NOTHROW
+        : d(other.d),
+          a(other.a)
+    {
+        other.d = nullptr;
+        other.a = nullptr;
+    }
+
+    QJsonArray &operator =(QJsonArray &&other) Q_DECL_NOTHROW
+    {
+        swap(other);
+        return *this;
+    }
+
     static QJsonArray fromStringList(const QStringList &list);
     static QJsonArray fromVariantList(const QVariantList &list);
     QVariantList toVariantList() const;
@@ -101,6 +115,12 @@ public:
     bool operator==(const QJsonArray &other) const;
     bool operator!=(const QJsonArray &other) const;
 
+    void swap(QJsonArray &other) Q_DECL_NOTHROW
+    {
+        qSwap(d, other.d);
+        qSwap(a, other.a);
+    }
+
     class const_iterator;
 
     class iterator {
@@ -243,6 +263,8 @@ private:
     QJsonPrivate::Array *a;
 };
 
+Q_DECLARE_SHARED_NOT_MOVABLE_UNTIL_QT6(QJsonArray)
+
 #if !defined(QT_NO_DEBUG_STREAM) && !defined(QT_JSON_READONLY)
 Q_CORE_EXPORT QDebug operator<<(QDebug, const QJsonArray &);
 #endif