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/qjsonvalue.cpp b/src/corelib/json/qjsonvalue.cpp
index 4b52014db1..cd7c1c63fc 100644
--- a/src/corelib/json/qjsonvalue.cpp
+++ b/src/corelib/json/qjsonvalue.cpp
@@ -284,6 +284,27 @@ QJsonValue &QJsonValue::operator =(const QJsonValue &other)
 }
 
 /*!
+    \fn QJsonValue::QJsonValue(QJsonValue &&other)
+    \since 5.10
+
+    Move-constructs a QJsonValue from \a other.
+*/
+
+/*!
+    \fn QJsonValue &QJsonValue::operator =(QJsonValue &&other)
+    \since 5.10
+
+    Move-assigns \a other to this value.
+*/
+
+/*!
+    \fn void QJsonValue::swap(QJsonValue &other)
+    \since 5.10
+
+    Swaps the value \a other with this. This operation is very fast and never fails.
+*/
+
+/*!
     \fn bool QJsonValue::isNull() const
 
     Returns \c true if the value is null.