QJsonArray iterators: use new comparison helper macros

New comparison macros are used for following classes:
- QJsonArray::iterator
- QJsonArray::const_iterator

Replace public operators operator==(), operator!=(), operator!<(), etc
of classes to friend methods comparesEqual(), compareThreeWay();

Use *_helper methods to have an access to protected members of
QCborValueConstRef class from friend functions.

Task-number: QTBUG-120300
Change-Id: I9b41b619107ce69d8b6dab4938232fab841aab51
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

3 files changed, 165 insertions, 47 deletions

diff --git a/src/corelib/serialization/qjsonarray.cpp b/src/corelib/serialization/qjsonarray.cpp
index 3ed91d4d0a..0c1b0ac7c8 100644
--- a/src/corelib/serialization/qjsonarray.cpp
+++ b/src/corelib/serialization/qjsonarray.cpp
@@ -603,6 +603,10 @@ bool comparesEqual(const QJsonArray &lhs, const QJsonValue &rhs) noexcept
     \inmodule QtCore
     \brief The QJsonArray::iterator class provides an STL-style non-const iterator for QJsonArray.
 
+    \compares strong
+    \compareswith strong QJsonArray::const_iterator
+    \endcompareswith
+
     QJsonArray::iterator allows you to iterate over a QJsonArray
     and to modify the array item associated with the
     iterator. If you want to iterate over a const QJsonArray, use
@@ -707,55 +711,55 @@ bool comparesEqual(const QJsonArray &lhs, const QJsonValue &rhs) noexcept
 */
 
 /*!
-    \fn bool QJsonArray::iterator::operator==(const iterator &other) const
-    \fn bool QJsonArray::iterator::operator==(const const_iterator &other) const
+    \fn bool QJsonArray::iterator::operator==(const iterator &lhs, const iterator &rhs)
+    \fn bool QJsonArray::iterator::operator==(const iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if \a other points to the same item as this
+    Returns \c true if \a lhs points to the same item as \a rhs
     iterator; otherwise returns \c false.
 
     \sa operator!=()
 */
 
 /*!
-    \fn bool QJsonArray::iterator::operator!=(const iterator &other) const
-    \fn bool QJsonArray::iterator::operator!=(const const_iterator &other) const
+    \fn bool QJsonArray::iterator::operator!=(const iterator &lhs, const iterator &rhs)
+    \fn bool QJsonArray::iterator::operator!=(const iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if \a other points to a different item than this
+    Returns \c true if \a lhs points to a different item than \a rhs
     iterator; otherwise returns \c false.
 
     \sa operator==()
 */
 
 /*!
-    \fn bool QJsonArray::iterator::operator<(const iterator& other) const
-    \fn bool QJsonArray::iterator::operator<(const const_iterator& other) const
+    \fn bool QJsonArray::iterator::operator<(const iterator &lhs, const iterator &rhs)
+    \fn bool QJsonArray::iterator::operator<(const iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if the item pointed to by this iterator is less than
-    the item pointed to by the \a other iterator.
+    Returns \c true if the item pointed to by \a lhs iterator is less than
+    the item pointed to by the \a rhs iterator.
 */
 
 /*!
-    \fn bool QJsonArray::iterator::operator<=(const iterator& other) const
-    \fn bool QJsonArray::iterator::operator<=(const const_iterator& other) const
+    \fn bool QJsonArray::iterator::operator<=(const iterator &lhs, const iterator &rhs)
+    \fn bool QJsonArray::iterator::operator<=(const iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if the item pointed to by this iterator is less than
-    or equal to the item pointed to by the \a other iterator.
+    Returns \c true if the item pointed to by \a lhs iterator is less than
+    or equal to the item pointed to by the \a rhs iterator.
 */
 
 /*!
-    \fn bool QJsonArray::iterator::operator>(const iterator& other) const
-    \fn bool QJsonArray::iterator::operator>(const const_iterator& other) const
+    \fn bool QJsonArray::iterator::operator>(const iterator &lhs, const iterator &rhs)
+    \fn bool QJsonArray::iterator::operator>(const iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if the item pointed to by this iterator is greater
-    than the item pointed to by the \a other iterator.
+    Returns \c true if the item pointed to by \a lhs iterator is greater
+    than the item pointed to by the \a rhs iterator.
 */
 
 /*!
-    \fn bool QJsonArray::iterator::operator>=(const iterator& other) const
-    \fn bool QJsonArray::iterator::operator>=(const const_iterator& other) const
+    \fn bool QJsonArray::iterator::operator>=(const iterator &lhs, const iterator &rhs)
+    \fn bool QJsonArray::iterator::operator>=(const iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if the item pointed to by this iterator is greater
-    than or equal to the item pointed to by the \a other iterator.
+    Returns \c true if the item pointed to by \a lhs iterator is greater
+    than or equal to the item pointed to by the \a rhs iterator.
 */
 
 /*! \fn QJsonArray::iterator &QJsonArray::iterator::operator++()
@@ -838,6 +842,10 @@ bool comparesEqual(const QJsonArray &lhs, const QJsonValue &rhs) noexcept
     \inmodule QtCore
     \brief The QJsonArray::const_iterator class provides an STL-style const iterator for QJsonArray.
 
+    \compares strong
+    \compareswith strong QJsonArray::iterator
+    \endcompareswith
+
     QJsonArray::const_iterator allows you to iterate over a
     QJsonArray. If you want to modify the QJsonArray as
     you iterate over it, use QJsonArray::iterator instead. It is generally a
@@ -930,48 +938,48 @@ bool comparesEqual(const QJsonArray &lhs, const QJsonValue &rhs) noexcept
     \sa operator+()
 */
 
-/*! \fn bool QJsonArray::const_iterator::operator==(const const_iterator &other) const
+/*! \fn bool QJsonArray::const_iterator::operator==(const const_iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if \a other points to the same item as this
+    Returns \c true if \a lhs points to the same item as \a rhs
     iterator; otherwise returns \c false.
 
     \sa operator!=()
 */
 
-/*! \fn bool QJsonArray::const_iterator::operator!=(const const_iterator &other) const
+/*! \fn bool QJsonArray::const_iterator::operator!=(const const_iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if \a other points to a different item than this
+    Returns \c true if \a lhs points to a different item than \a rhs
     iterator; otherwise returns \c false.
 
     \sa operator==()
 */
 
 /*!
-    \fn bool QJsonArray::const_iterator::operator<(const const_iterator& other) const
+    \fn bool QJsonArray::const_iterator::operator<(const const_iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if the item pointed to by this iterator is less than
-    the item pointed to by the \a other iterator.
+    Returns \c true if the item pointed to by \a lhs iterator is less than
+    the item pointed to by the \a rhs iterator.
 */
 
 /*!
-    \fn bool QJsonArray::const_iterator::operator<=(const const_iterator& other) const
+    \fn bool QJsonArray::const_iterator::operator<=(const const_iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if the item pointed to by this iterator is less than
-    or equal to the item pointed to by the \a other iterator.
+    Returns \c true if the item pointed to by \a lhs iterator is less than
+    or equal to the item pointed to by the \a rhs iterator.
 */
 
 /*!
-    \fn bool QJsonArray::const_iterator::operator>(const const_iterator& other) const
+    \fn bool QJsonArray::const_iterator::operator>(const const_iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if the item pointed to by this iterator is greater
-    than the item pointed to by the \a other iterator.
+    Returns \c true if the item pointed to by \a lhs iterator is greater
+    than the item pointed to by the \a rhs iterator.
 */
 
 /*!
-    \fn bool QJsonArray::const_iterator::operator>=(const const_iterator& other) const
+    \fn bool QJsonArray::const_iterator::operator>=(const const_iterator &lhs, const const_iterator &rhs)
 
-    Returns \c true if the item pointed to by this iterator is greater
-    than or equal to the item pointed to by the \a other iterator.
+    Returns \c true if the item pointed to by \a lhs iterator is greater
+    than or equal to the item pointed to by the \a rhs iterator.
 */
 
 /*! \fn QJsonArray::const_iterator &QJsonArray::const_iterator::operator++()
diff --git a/src/corelib/serialization/qjsonarray.h b/src/corelib/serialization/qjsonarray.h
index a2baa7738c..26a04e9196 100644
--- a/src/corelib/serialization/qjsonarray.h
+++ b/src/corelib/serialization/qjsonarray.h
@@ -94,24 +94,26 @@ public:
         inline QJsonValueRef *operator->() { return &item; }
         inline QJsonValueRef operator[](qsizetype j) const { return *(*this + j); }
 
+#if QT_CORE_REMOVED_SINCE(6, 8)
         inline bool operator==(const iterator &o) const
         { return item.d == o.item.d && item.index == o.item.index; }
-        inline bool operator!=(const iterator &o) const { return !(*this == o); }
+        inline bool operator!=(const iterator &o) const { return !operator==(o); }
         inline bool operator<(const iterator &other) const
         { Q_ASSERT(item.d == other.item.d); return item.index < other.item.index; }
         inline bool operator<=(const iterator &other) const
         { Q_ASSERT(item.d == other.item.d); return item.index <= other.item.index; }
-        inline bool operator>(const iterator &other) const { return !(*this <= other); }
-        inline bool operator>=(const iterator &other) const { return !(*this < other); }
+        inline bool operator>(const iterator &other) const { return !operator<=(other); }
+        inline bool operator>=(const iterator &other) const { return !operator<(other); }
         inline bool operator==(const const_iterator &o) const
         { return item.d == o.item.d && item.index == o.item.index; }
-        inline bool operator!=(const const_iterator &o) const { return !(*this == o); }
+        inline bool operator!=(const const_iterator &o) const { return !operator==(o); }
         inline bool operator<(const const_iterator &other) const
         { Q_ASSERT(item.d == other.item.d); return item.index < other.item.index; }
         inline bool operator<=(const const_iterator &other) const
         { Q_ASSERT(item.d == other.item.d); return item.index <= other.item.index; }
-        inline bool operator>(const const_iterator &other) const { return !(*this <= other); }
-        inline bool operator>=(const const_iterator &other) const { return !(*this < other); }
+        inline bool operator>(const const_iterator &other) const { return !operator<=(other); }
+        inline bool operator>=(const const_iterator &other) const { return !operator<(other); }
+#endif
         inline iterator &operator++() { ++item.index; return *this; }
         inline iterator operator++(int) { iterator n = *this; ++item.index; return n; }
         inline iterator &operator--() { item.index--; return *this; }
@@ -123,6 +125,53 @@ public:
         inline qsizetype operator-(iterator j) const { return item.index - j.item.index; }
 
     private:
+        // Helper functions
+        static bool comparesEqual_helper(const iterator &lhs, const iterator &rhs) noexcept
+        {
+            return lhs.item.d == rhs.item.d && lhs.item.index == rhs.item.index;
+        }
+
+        static bool comparesEqual_helper(const iterator &lhs, const const_iterator &rhs) noexcept
+        {
+            return lhs.item.d == rhs.item.d && lhs.item.index == rhs.item.index;
+        }
+
+        static Qt::strong_ordering compareThreeWay_helper(const iterator &lhs,
+                                                          const iterator &rhs) noexcept
+        {
+            Q_ASSERT(lhs.item.d == rhs.item.d);
+            return Qt::compareThreeWay(lhs.item.index, rhs.item.index);
+        }
+
+        static Qt::strong_ordering compareThreeWay_helper(const iterator &lhs,
+                                                          const const_iterator &rhs) noexcept
+        {
+            Q_ASSERT(lhs.item.d == rhs.item.d);
+            return Qt::compareThreeWay(lhs.item.index, rhs.item.index);
+        }
+
+        // Compare friends
+        friend bool comparesEqual(const iterator &lhs, const iterator &rhs) noexcept
+        {
+            return comparesEqual_helper(lhs, rhs);
+        }
+        friend Qt::strong_ordering compareThreeWay(const iterator &lhs,
+                                                   const iterator &rhs) noexcept
+        {
+            return compareThreeWay_helper(lhs, rhs);
+        }
+        Q_DECLARE_STRONGLY_ORDERED(iterator)
+        friend bool comparesEqual(const iterator &lhs, const const_iterator &rhs) noexcept
+        {
+            return comparesEqual_helper(lhs, rhs);
+        }
+        friend Qt::strong_ordering compareThreeWay(const iterator &lhs,
+                                                   const const_iterator &rhs) noexcept
+        {
+            return compareThreeWay_helper(lhs, rhs);
+        }
+        Q_DECLARE_STRONGLY_ORDERED(iterator, const_iterator)
+
         QJsonValueRef item;
         friend class QJsonArray;
     };
@@ -152,15 +201,17 @@ public:
         inline const QJsonValueConstRef *operator->() const { return &item; }
 
         inline QJsonValueConstRef operator[](qsizetype j) const { return *(*this + j); }
+#if QT_CORE_REMOVED_SINCE(6, 8)
         inline bool operator==(const const_iterator &o) const
         { return item.d == o.item.d && item.index == o.item.index; }
-        inline bool operator!=(const const_iterator &o) const { return !(*this == o); }
+        inline bool operator!=(const const_iterator &o) const { return !operator==(o); }
         inline bool operator<(const const_iterator &other) const
         { Q_ASSERT(item.d == other.item.d); return item.index < other.item.index; }
         inline bool operator<=(const const_iterator &other) const
         { Q_ASSERT(item.d == other.item.d); return item.index <= other.item.index; }
-        inline bool operator>(const const_iterator &other) const { return !(*this <= other); }
-        inline bool operator>=(const const_iterator &other) const { return !(*this < other); }
+        inline bool operator>(const const_iterator &other) const { return !operator<=(other); }
+        inline bool operator>=(const const_iterator &other) const { return !operator<(other); }
+#endif
         inline const_iterator &operator++() { ++item.index; return *this; }
         inline const_iterator operator++(int) { const_iterator n = *this; ++item.index; return n; }
         inline const_iterator &operator--() { item.index--; return *this; }
@@ -172,6 +223,30 @@ public:
         inline qsizetype operator-(const_iterator j) const { return item.index - j.item.index; }
 
     private:
+        // Helper functions
+        static bool comparesEqual_helper(const const_iterator &lhs,
+                                         const const_iterator &rhs) noexcept
+        {
+            return lhs.item.d == rhs.item.d && lhs.item.index == rhs.item.index;
+        }
+        static Qt::strong_ordering compareThreeWay_helper(const const_iterator &lhs,
+                                                          const const_iterator &rhs) noexcept
+        {
+            Q_ASSERT(lhs.item.d == rhs.item.d);
+            return Qt::compareThreeWay(lhs.item.index, rhs.item.index);
+        }
+
+        // Compare friends
+        friend bool comparesEqual(const const_iterator &lhs, const const_iterator &rhs) noexcept
+        {
+            return comparesEqual_helper(lhs, rhs);
+        }
+        friend Qt::strong_ordering compareThreeWay(const const_iterator &lhs,
+                                                   const const_iterator &rhs) noexcept
+        {
+            return compareThreeWay_helper(lhs, rhs);
+        }
+        Q_DECLARE_STRONGLY_ORDERED(const_iterator)
         QJsonValueConstRef item;
         friend class QJsonArray;
     };
diff --git a/tests/auto/corelib/serialization/json/tst_qtjson.cpp b/tests/auto/corelib/serialization/json/tst_qtjson.cpp
index 2f3e8e07d5..51af8ab78e 100644
--- a/tests/auto/corelib/serialization/json/tst_qtjson.cpp
+++ b/tests/auto/corelib/serialization/json/tst_qtjson.cpp
@@ -176,6 +176,10 @@ void tst_QtJson::initTestCase()
 void tst_QtJson::compareCompiles()
 {
     QTestPrivate::testEqualityOperatorsCompile<QJsonArray>();
+    QTestPrivate::testAllComparisonOperatorsCompile<QJsonArray::iterator>();
+    QTestPrivate::testAllComparisonOperatorsCompile<QJsonArray::const_iterator>();
+    QTestPrivate::testAllComparisonOperatorsCompile<QJsonArray::iterator,
+                                                    QJsonArray::const_iterator>();
     QTestPrivate::testEqualityOperatorsCompile<QJsonDocument>();
     QTestPrivate::testEqualityOperatorsCompile<QJsonObject>();
     QTestPrivate::testEqualityOperatorsCompile<QJsonValue>();
@@ -1210,7 +1214,11 @@ void tst_QtJson::testArrayIteration()
     int i = 0;
     for (QJsonArray::iterator it = array.begin(); it != array.end(); ++it, ++i) {
         QJsonValue value = (*it);
+        QJsonArray::iterator it1 = it;
         QCOMPARE((double)i, value.toDouble());
+        QT_TEST_EQUALITY_OPS(QJsonArray::iterator(), QJsonArray::iterator(), true);
+        QT_TEST_EQUALITY_OPS(QJsonArray::iterator(), it, false);
+        QT_TEST_EQUALITY_OPS(it1, it, true);
     }
 
     QCOMPARE(array.begin()->toDouble(), array.constBegin()->toDouble());
@@ -1265,6 +1273,13 @@ void tst_QtJson::testArrayIteration()
         QCOMPARE(QJsonValue(*it2).toDouble(), 7.);
         it2 = it - 1;
         QCOMPARE(QJsonValue(*it2).toDouble(), 1.);
+        QT_TEST_EQUALITY_OPS(it, it2, false);
+        it = array.begin();
+        QT_TEST_EQUALITY_OPS(it, array.begin(), true);
+        it2 = it + 5;
+        QT_TEST_ALL_COMPARISON_OPS(it2, it,  Qt::strong_ordering::greater);
+        it += 5;
+        QT_TEST_EQUALITY_OPS(it, it2, true);
     }
 
     {
@@ -1284,6 +1299,26 @@ void tst_QtJson::testArrayIteration()
         it = array.erase(it);
     QCOMPARE(array.size() , 0);
     QCOMPARE(it, array.end());
+    QT_TEST_EQUALITY_OPS(it, array.end(), true);
+
+    {
+        int i = 0;
+        for (QJsonArray::const_iterator it = array.constBegin();
+             it != array.constEnd(); ++it, ++i) {
+            QJsonArray::const_iterator it1 = it;
+            QT_TEST_EQUALITY_OPS(QJsonArray::const_iterator(), QJsonArray::const_iterator(), true);
+            QT_TEST_EQUALITY_OPS(QJsonArray::const_iterator(), it, false);
+            QT_TEST_EQUALITY_OPS(it1, it, true);
+        }
+    }
+
+    {
+        QJsonArray::iterator nonConstIt = array.begin();
+        QJsonArray::const_iterator it = array.constBegin();
+        QT_TEST_EQUALITY_OPS(nonConstIt, it, true);
+        it+=1;
+        QT_TEST_ALL_COMPARISON_OPS(nonConstIt, it, Qt::strong_ordering::less);
+    }
 }
 
 void tst_QtJson::testObjectFind()