Tracing HeapListHashSet<> iterators.

third_party/WebKit/Source/wtf/ListHashSet.h

 /*
  * Copyright (C) 2005, 2006, 2007, 2008, 2011, 2012 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2011, Benjamin Poulain <ikipou@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 520 matching lines @@
   // Comparison.
   bool operator==(const ListHashSetIterator& other) const {
     return m_iterator == other.m_iterator;
   }
   bool operator!=(const ListHashSetIterator& other) const {
     return m_iterator != other.m_iterator;
   }
 
   operator const_iterator() const { return m_iterator; }
 
+  template <typename VisitorDispatcher>
+  void trace(VisitorDispatcher visitor) {
+    m_iterator.trace(visitor);
+  }
+
  private:
   Node* getNode() { return m_iterator.getNode(); }
 
   const_iterator m_iterator;
 
   template <typename T, size_t inlineCapacity, typename U, typename V>
   friend class ListHashSet;
 };
 
 template <typename Set>
@@ skipping 37 matching lines @@
   // Postfix ++ and -- intentionally omitted.
 
   // Comparison.
   bool operator==(const ListHashSetConstIterator& other) const {
     return m_position == other.m_position;
   }
   bool operator!=(const ListHashSetConstIterator& other) const {
     return m_position != other.m_position;
   }
 
+  template <typename VisitorDispatcher>
+  void trace(VisitorDispatcher visitor) {
+    visitor->trace(*m_set);
+    visitor->trace(m_position);
+  }
+
  private:
   Node* getNode() { return m_position; }
 
   const Set* m_set;
   Node* m_position;
 
   template <typename T, size_t inlineCapacity, typename U, typename V>
   friend class ListHashSet;
 };
 
@@ skipping 34 matching lines @@
   // Comparison.
   bool operator==(const ListHashSetReverseIterator& other) const {
     return m_iterator == other.m_iterator;
   }
   bool operator!=(const ListHashSetReverseIterator& other) const {
     return m_iterator != other.m_iterator;
   }
 
   operator const_reverse_iterator() const { return m_iterator; }
 
+  template <typename VisitorDispatcher>
+  void trace(VisitorDispatcher visitor) {
+    m_iterator.trace(visitor);

[haraken, 2016/12/20 02:53:05]

Just to confirm: This iterator is just pointing to a Node of ListHashSet and not
pointing to anything middle in a backing storage, right?

[sof, 2016/12/20 06:37:08]

Yes, the nodes in this list are separately allocated, which the backing store
then keeps pointers to, for faster access than the linked view. The iterator
refers to the current node + the ListHashSet<> itself for when it needs to get
at the head/tail of the list.

+  }
+
  private:
   Node* getNode() { return m_iterator.node(); }
 
   const_reverse_iterator m_iterator;
 
   template <typename T, size_t inlineCapacity, typename U, typename V>
   friend class ListHashSet;
 };
 
 template <typename Set>
@@ skipping 37 matching lines @@
   // Postfix ++ and -- intentionally omitted.
 
   // Comparison.
   bool operator==(const ListHashSetConstReverseIterator& other) const {
     return m_position == other.m_position;
   }
   bool operator!=(const ListHashSetConstReverseIterator& other) const {
     return m_position != other.m_position;
   }
 
+  template <typename VisitorDispatcher>
+  void trace(VisitorDispatcher visitor) {
+    visitor->trace(*m_set);
+    visitor->trace(m_position);
+  }
+
  private:
   Node* getNode() { return m_position; }
 
   const Set* m_set;
   Node* m_position;
 
   template <typename T, size_t inlineCapacity, typename U, typename V>
   friend class ListHashSet;
 };
 
@@ skipping 388 matching lines @@
   // through the HashTable. That includes m_head and m_tail so we do not have
   // to explicitly trace them here.
   m_impl.trace(visitor);
 }
 
 }  // namespace WTF
 
 using WTF::ListHashSet;
 
 #endif  // WTF_ListHashSet_h