QByteArray: add {const_,reverse_iterator}, {c,}r{begin,end}()

Had to mark {,c,const}{begin,end}() inline, since they are, and mingw
complains about inconsistent dllimport attributes.

[ChangeLog][QtCore][QByteArray] Added rbegin(), crbegin(), rend(), crend(),
and reverse_iterator and const_reverse_iterator typedefs.

Task-number: QTBUG-25919
Change-Id: Id5aefb52635f029305135afcd99db0b036a7af82
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/tools/qbytearray.cpp

@@ -919,6 +919,52 @@ static inline char qToLower(char c)
     \sa constBegin(), end()
 */
 
+/*! \fn QByteArray::reverse_iterator QByteArray::rbegin()
+    \since 5.6
+
+    Returns a \l{STL-style iterators}{STL-style} reverse iterator pointing to the first
+    character in the byte-array, in reverse order.
+
+    \sa begin(), crbegin(), rend()
+*/
+
+/*! \fn QByteArray::const_reverse_iterator QByteArray::rbegin() const
+    \since 5.6
+    \overload
+*/
+
+/*! \fn QByteArray::const_reverse_iterator QByteArray::crbegin() const
+    \since 5.6
+
+    Returns a const \l{STL-style iterators}{STL-style} reverse iterator pointing to the first
+    character in the byte-array, in reverse order.
+
+    \sa begin(), rbegin(), rend()
+*/
+
+/*! \fn QByteArray::reverse_iterator QByteArray::rend()
+    \since 5.6
+
+    Returns a \l{STL-style iterators}{STL-style} reverse iterator pointing to one past
+    the last character in the byte-array, in reverse order.
+
+    \sa end(), crend(), rbegin()
+*/
+
+/*! \fn QByteArray::const_reverse_iterator QByteArray::rend() const
+    \since 5.6
+    \overload
+*/
+
+/*! \fn QByteArray::const_reverse_iterator QByteArray::crend() const
+    \since 5.6
+
+    Returns a const \l{STL-style iterators}{STL-style} reverse iterator pointing to one
+    past the last character in the byte-array, in reverse order.
+
+    \sa end(), rend(), rbegin()
+*/
+
 /*! \fn void QByteArray::push_back(const QByteArray &other)
 
     This function is provided for STL compatibility. It is equivalent

src/corelib/tools/qbytearray.h

@@ -43,6 +43,7 @@
 #include <stdarg.h>
 
 #include <string>
+#include <iterator>
 
 #ifdef truncate
 #error qbytearray.h must be included before any header file that defines truncate
@@ -390,14 +391,22 @@ public:
     typedef const char *const_iterator;
     typedef iterator Iterator;
     typedef const_iterator ConstIterator;
-    iterator begin();
-    const_iterator begin() const;
-    const_iterator cbegin() const;
-    const_iterator constBegin() const;
-    iterator end();
-    const_iterator end() const;
-    const_iterator cend() const;
-    const_iterator constEnd() const;
+    typedef std::reverse_iterator<iterator> reverse_iterator;
+    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+    inline iterator begin();
+    inline const_iterator begin() const;
+    inline const_iterator cbegin() const;
+    inline const_iterator constBegin() const;
+    inline iterator end();
+    inline const_iterator end() const;
+    inline const_iterator cend() const;
+    inline const_iterator constEnd() const;
+    reverse_iterator rbegin() { return reverse_iterator(end()); }
+    reverse_iterator rend() { return reverse_iterator(begin()); }
+    const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); }
+    const_reverse_iterator rend() const { return const_reverse_iterator(begin()); }
+    const_reverse_iterator crbegin() const { return const_reverse_iterator(end()); }
+    const_reverse_iterator crend() const { return const_reverse_iterator(begin()); }
 
     // stl compatibility
     typedef int size_type;

tests/auto/corelib/tools/qbytearray/tst_qbytearray.cpp

@@ -67,6 +67,7 @@ private slots:
     void endsWith_data();
     void endsWith();
     void endsWith_char();
+    void reverseIterators();
     void split_data();
     void split();
     void base64_data();
@@ -540,6 +541,20 @@ void tst_QByteArray::endsWith_char()
     QVERIFY(!QByteArray().endsWith('\0'));
 }
 
+void tst_QByteArray::reverseIterators()
+{
+    QByteArray s = "1234";
+    QByteArray sr = s;
+    std::reverse(sr.begin(), sr.end());
+    const QByteArray &csr = sr;
+    QVERIFY(std::equal(s.begin(), s.end(), sr.rbegin()));
+    QVERIFY(std::equal(s.begin(), s.end(), sr.crbegin()));
+    QVERIFY(std::equal(s.begin(), s.end(), csr.rbegin()));
+    QVERIFY(std::equal(sr.rbegin(), sr.rend(), s.begin()));
+    QVERIFY(std::equal(sr.crbegin(), sr.crend(), s.begin()));
+    QVERIFY(std::equal(csr.rbegin(), csr.rend(), s.begin()));
+}
+
 void tst_QByteArray::split_data()
 {
     QTest::addColumn<QByteArray>("sample");