QVector: add move(int,int) for QList compat

Change-Id: I67948621313f2e7c69abe7ef95ee82ca64c6512a
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

src/corelib/tools/qvector.cpp

@@ -688,6 +688,16 @@
     \sa takeFirst(), takeLast(), QList::takeAt()
 */
 
+/*! \fn void QVector::move(int from, int to)
+    \since 5.6
+
+    Moves the item at index position \a from to index position \a to.
+
+    Provided for compatibility with QList.
+
+    \sa QList::move()
+*/
+
 /*! \fn void QVector::removeFirst()
     \since 5.1
     Removes the first item in the vector. Calling this function is

src/corelib/tools/qvector.h

@@ -172,6 +172,19 @@ public:
     }
     int length() const { return size(); }
     T takeAt(int i) { T t = at(i); remove(i); return t; }
+    void move(int from, int to)
+    {
+        Q_ASSERT_X(from >= 0 && from < size(), "QVector::move(int,int)", "'from' is out-of-range");
+        Q_ASSERT_X(to >= 0 && to < size(), "QVector::move(int,int)", "'to' is out-of-range");
+        if (from == to) // don't detach when no-op
+            return;
+        detach();
+        T * const b = d->begin();
+        if (from < to)
+            std::rotate(b + from, b + from + 1, b + to + 1);
+        else
+            std::rotate(b + to, b + from, b + from + 1);
+    }
 
     // STL-style
     typedef typename Data::iterator iterator;

tests/auto/corelib/tools/qvector/tst_qvector.cpp

@@ -240,6 +240,9 @@ private slots:
     void last() const;
     void lastIndexOf() const;
     void mid() const;
+    void moveInt() const;
+    void moveMovable() const;
+    void moveCustom() const;
     void prependInt() const;
     void prependMovable() const;
     void prependCustom() const;
@@ -312,6 +315,7 @@ private:
     template<typename T> void fromList() const;
     template<typename T> void insert() const;
     template<typename T> void qhash() const;
+    template<typename T> void move() const;
     template<typename T> void prepend() const;
     template<typename T> void remove() const;
     template<typename T> void size() const;
@@ -350,6 +354,14 @@ const Movable SimpleValue<Movable>::Values[] = { 110, 105, 101, 114, 111, 98 };
 template<>
 const Custom SimpleValue<Custom>::Values[] = { 110, 105, 101, 114, 111, 98 };
 
+// Make some macros for the tests to use in order to be slightly more readable...
+#define T_FOO SimpleValue<T>::at(0)
+#define T_BAR SimpleValue<T>::at(1)
+#define T_BAZ SimpleValue<T>::at(2)
+#define T_CAT SimpleValue<T>::at(3)
+#define T_DOG SimpleValue<T>::at(4)
+#define T_BLAH SimpleValue<T>::at(5)
+
 void tst_QVector::constructors_empty() const
 {
     QVector<int> emptyInt;
@@ -1604,6 +1616,44 @@ void tst_QVector::qhash() const
     QCOMPARE(qHash(l1), qHash(l2));
 }
 
+template <typename T>
+void tst_QVector::move() const
+{
+    QVector<T> list;
+    list << T_FOO << T_BAR << T_BAZ;
+
+    // move an item
+    list.move(0, list.count() - 1);
+    QCOMPARE(list, QVector<T>() << T_BAR << T_BAZ << T_FOO);
+
+    // move it back
+    list.move(list.count() - 1, 0);
+    QCOMPARE(list, QVector<T>() << T_FOO << T_BAR << T_BAZ);
+
+    // move an item in the middle
+    list.move(1, 0);
+    QCOMPARE(list, QVector<T>() << T_BAR << T_FOO << T_BAZ);
+}
+
+void tst_QVector::moveInt() const
+{
+    move<int>();
+}
+
+void tst_QVector::moveMovable() const
+{
+    const int instancesCount = Movable::counter.loadAcquire();
+    move<Movable>();
+    QCOMPARE(instancesCount, Movable::counter.loadAcquire());
+}
+
+void tst_QVector::moveCustom() const
+{
+    const int instancesCount = Custom::counter.loadAcquire();
+    move<Custom>();
+    QCOMPARE(instancesCount, Custom::counter.loadAcquire());
+}
+
 template<typename T>
 void tst_QVector::prepend() const
 {