CBOR: Add missing clear() methods to the two container classes

Change-Id: Id59bdd8f1a804b809e22fffd153fd5174b58014d
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/corelib/serialization/qcborarray.cpp

@@ -185,12 +185,22 @@ qsizetype QCborArray::size() const noexcept
     return d ? d->elements.size() : 0;
 }
 
+/*!
+    Empties this array.
+
+    \sa isEmpty()
+ */
+void QCborArray::clear()
+{
+    d.reset();
+}
+
 /*!
     \fn bool QCborArray::isEmpty() const
 
     Returns true if this QCborArray is empty (that is if size() is 0).
 
-    \sa size()
+    \sa size(), clear()
  */
 
 /*!

src/corelib/serialization/qcborarray.h

@@ -180,6 +180,7 @@ public:
 
     qsizetype size() const noexcept;
     bool isEmpty() const { return size() == 0; }
+    void clear();
 
     QCborValue at(qsizetype i) const;
     QCborValue first() const { return at(0); }

src/corelib/serialization/qcbormap.cpp

@@ -270,7 +270,7 @@ QCborMap &QCborMap::operator=(const QCborMap &other) noexcept
 
     Returns true if this map is empty (that is, size() is 0).
 
-    \sa size()
+    \sa size(), clear()
  */
 
 /*!
@@ -283,6 +283,16 @@ qsizetype QCborMap::size() const noexcept
     return d ? d->elements.size() / 2 : 0;
 }
 
+/*!
+    Empties this map.
+
+    \sa isEmpty()
+ */
+void QCborMap::clear()
+{
+    d.reset();
+}
+
 /*!
     Returns a list of all keys in this map.
 

src/corelib/serialization/qcbormap.h

@@ -184,6 +184,7 @@ public:
 
     qsizetype size() const noexcept Q_DECL_PURE_FUNCTION;
     bool isEmpty() const { return size() == 0; }
+    void clear();
     QVector<QCborValue> keys() const;
 
     QCborValue value(qint64 key) const