Introduce EphemeralRange::nodes() helper to traverse over a range.

third_party/WebKit/Source/core/editing/EphemeralRange.h

Index: third_party/WebKit/Source/core/editing/EphemeralRange.h
diff --git a/third_party/WebKit/Source/core/editing/EphemeralRange.h b/third_party/WebKit/Source/core/editing/EphemeralRange.h
index 5512100955b9ffc4b3645580a3fe62002ab97e87..fd76e4779a20eeedf8a6d85fea6f93060d026ddd 100644
--- a/third_party/WebKit/Source/core/editing/EphemeralRange.h
+++ b/third_party/WebKit/Source/core/editing/EphemeralRange.h
@@ -12,6 +12,44 @@ namespace blink {
 class Document;
 class Range;
 
+// We should restrict access to the unwanted version of |TraversalRange::end()| function.
+template <class Iterator>
+class TraversalRangeNodes : private TraversalRange<Iterator> {
+    STACK_ALLOCATED();
+public:
+    using StartNodeType = typename TraversalRange<Iterator>::StartNodeType;
+    TraversalRangeNodes(const StartNodeType* start, const StartNodeType* pastEndNode)
+        : TraversalRange<Iterator>(start), m_pastEndNode(pastEndNode) { }
+
+    using TraversalRange<Iterator>::begin;
+
+    Iterator end() { return Iterator(m_pastEndNode); }
+
+private:
+    const Member<const StartNodeType> m_pastEndNode;
+};
+
+// This class acts like |TraversalNextIterator| but in addition
+// it allows to set current position and checks |m_current| pointer before
+// dereferencing.
+template <class TraversalNext>
+class CheckedTraversalNextIterator : public TraversalIteratorBase<TraversalNext> {
+    STACK_ALLOCATED();
+
+    using TraversalIteratorBase<TraversalNext>::m_current;
+public:
+    using StartNodeType = typename TraversalNext::TraversalNodeType;
+    explicit CheckedTraversalNextIterator(const StartNodeType* start) : TraversalIteratorBase<TraversalNext>(const_cast<StartNodeType*>(start)) { }
+
+    void operator++()

[yosin_UTC9, 2016/08/18 02:11:09]

Interesting, I never know we can implement |operator++()| to return |void|.

[Andrey Kraynov, 2016/08/18 10:16:33]

Yep, |operator++()| is just a regular function =)
Although, with |void| it will not allow to write |Iterator next = ++prev;|

+    {
+        DCHECK(m_current);
+        m_current = TraversalNext::next(*m_current);
+    }
+    bool isNull() const { return !m_current; }

[yosin_UTC9, 2016/08/18 02:11:09]

We may not want to have |isNull()| and |setCurrent()|.
Let's revise impl of
|DeleteSelectionCommand::makeStylingElementsDirectChildrenOfEditableRootToPreventStyleLoss()|.

[Andrey Kraynov, 2016/08/18 10:16:33]

Done.

+    void setCurrent(Node* current) { m_current = current; }
+};
+
 // Unlike |Range| objects, |EphemeralRangeTemplate| objects aren't relocated.
 // You should not use |EphemeralRangeTemplate| objects after DOM modification.
 //
@@ -38,6 +76,8 @@ template <typename Strategy>
 class CORE_TEMPLATE_CLASS_EXPORT EphemeralRangeTemplate final {
     STACK_ALLOCATED();
 public:
+    using RangeTraversal = TraversalRangeNodes<CheckedTraversalNextIterator<Strategy>>;
+
     EphemeralRangeTemplate(const PositionTemplate<Strategy>& start, const PositionTemplate<Strategy>& end);
     EphemeralRangeTemplate(const EphemeralRangeTemplate& other);
     // |position| should be |Position::isNull()| or in-document.
@@ -65,6 +105,8 @@ public:
     }
     bool isNotNull() const { return !isNull(); }
 
+    RangeTraversal nodes() const;
+
     DEFINE_INLINE_TRACE()
     {
         visitor->trace(m_startPosition);