QLinkedList/QSet: add {const_,}reverse_iterator, {c,}r{begin,end}()

Now all Qt sequential containers consistently provide reverse iterators.

The associative ones, by way of not returning std::pair from op*, can't
just use std::reverse_iterator. They would miss .key() and .value() methods.
So that has to wait for 5.7.

The reverse versions of the new key_iterators can also just use
std::reverse_iterator, but I'm afraid that after bikeshedding over
keyRBegin() vs. rKeyBegin() vs. reverseKeyBegin() vs. rkbegin()
vs. krbegin() (<-- of course, what else?), it would anyway be too
late for 5.6, so defer, too.

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

Task-number: QTBUG-25919
Change-Id: I58316fffade469e9a42c61d7aa1455ae3443fd94
Reviewed-by: Sérgio Martins <sergio.martins@kdab.com>
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

2 files changed, 32 insertions, 0 deletions

diff --git a/tests/auto/corelib/tools/qlinkedlist/tst_qlinkedlist.cpp b/tests/auto/corelib/tools/qlinkedlist/tst_qlinkedlist.cpp
index 2e829bb05e..d3ace40164 100644
--- a/tests/auto/corelib/tools/qlinkedlist/tst_qlinkedlist.cpp
+++ b/tests/auto/corelib/tools/qlinkedlist/tst_qlinkedlist.cpp
@@ -204,6 +204,7 @@ private slots:
     void removeOneInt() const;
     void removeOneMovable() const;
     void removeOneComplex() const;
+    void reverseIterators() const;
     void startsWithInt() const;
     void startsWithMovable() const;
     void startsWithComplex() const;
@@ -754,6 +755,21 @@ void tst_QLinkedList::removeOneComplex() const
     QCOMPARE(liveCount, Complex::getLiveCount());
 }
 
+void tst_QLinkedList::reverseIterators() const
+{
+    QLinkedList<int> l;
+    l << 1 << 2 << 3 << 4;
+    QLinkedList<int> lr = l;
+    std::reverse(lr.begin(), lr.end());
+    const QLinkedList<int> &clr = lr;
+    QVERIFY(std::equal(l.begin(), l.end(), lr.rbegin()));
+    QVERIFY(std::equal(l.begin(), l.end(), lr.crbegin()));
+    QVERIFY(std::equal(l.begin(), l.end(), clr.rbegin()));
+    QVERIFY(std::equal(lr.rbegin(), lr.rend(), l.begin()));
+    QVERIFY(std::equal(lr.crbegin(), lr.crend(), l.begin()));
+    QVERIFY(std::equal(clr.rbegin(), clr.rend(), l.begin()));
+}
+
 template<typename T>
 void tst_QLinkedList::startsWith() const
 {
diff --git a/tests/auto/corelib/tools/qset/tst_qset.cpp b/tests/auto/corelib/tools/qset/tst_qset.cpp
index 134d257d64..fe4d81085c 100644
--- a/tests/auto/corelib/tools/qset/tst_qset.cpp
+++ b/tests/auto/corelib/tools/qset/tst_qset.cpp
@@ -65,6 +65,7 @@ private slots:
     void begin();
     void end();
     void insert();
+    void reverseIterators();
     void setOperations();
     void stlIterator();
     void stlMutableIterator();
@@ -555,6 +556,21 @@ void tst_QSet::insert()
     }
 }
 
+void tst_QSet::reverseIterators()
+{
+    QSet<int> s;
+    s << 1 << 17 << 61 << 127 << 911;
+    std::vector<int> v(s.begin(), s.end());
+    std::reverse(v.begin(), v.end());
+    const QSet<int> &cs = s;
+    QVERIFY(std::equal(v.begin(), v.end(), s.rbegin()));
+    QVERIFY(std::equal(v.begin(), v.end(), s.crbegin()));
+    QVERIFY(std::equal(v.begin(), v.end(), cs.rbegin()));
+    QVERIFY(std::equal(s.rbegin(), s.rend(), v.begin()));
+    QVERIFY(std::equal(s.crbegin(), s.crend(), v.begin()));
+    QVERIFY(std::equal(cs.rbegin(), cs.rend(), v.begin()));
+}
+
 void tst_QSet::setOperations()
 {
     QSet<QString> set1, set2;