diff -r 000000000000 -r 6474c204b198 docshell/base/nsDocShellEnumerator.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/docshell/base/nsDocShellEnumerator.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,112 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsDocShellEnumerator_h___
+#define nsDocShellEnumerator_h___
+
+#include "nsISimpleEnumerator.h"
+#include "nsTArray.h"
+#include "nsIWeakReferenceUtils.h"
+
+class nsIDocShellTreeItem;
+
+/*
+// {13cbc281-35ae-11d5-be5b-bde0edece43c}
+#define NS_DOCSHELL_FORWARDS_ENUMERATOR_CID  \
+{ 0x13cbc281, 0x35ae, 0x11d5, { 0xbe, 0x5b, 0xbd, 0xe0, 0xed, 0xec, 0xe4, 0x3c } }
+
+#define NS_DOCSHELL_FORWARDS_ENUMERATOR_CONTRACTID \
+"@mozilla.org/docshell/enumerator-forwards;1"
+
+// {13cbc282-35ae-11d5-be5b-bde0edece43c}
+#define NS_DOCSHELL_BACKWARDS_ENUMERATOR_CID  \
+{ 0x13cbc282, 0x35ae, 0x11d5, { 0xbe, 0x5b, 0xbd, 0xe0, 0xed, 0xec, 0xe4, 0x3c } }
+
+#define NS_DOCSHELL_BACKWARDS_ENUMERATOR_CONTRACTID \
+"@mozilla.org/docshell/enumerator-backwards;1"
+*/
+
+class nsDocShellEnumerator : public nsISimpleEnumerator
+{
+protected:
+
+  enum {
+    enumerateForwards,
+    enumerateBackwards
+  };
+  
+public:
+
+                              nsDocShellEnumerator(int32_t inEnumerationDirection);
+  virtual                     ~nsDocShellEnumerator();
+
+  // nsISupports
+  NS_DECL_ISUPPORTS
+  
+  // nsISimpleEnumerator
+  NS_DECL_NSISIMPLEENUMERATOR
+  
+public:
+
+  nsresult                    GetEnumerationRootItem(nsIDocShellTreeItem * *aEnumerationRootItem);
+  nsresult                    SetEnumerationRootItem(nsIDocShellTreeItem * aEnumerationRootItem);
+  
+  nsresult                    GetEnumDocShellType(int32_t *aEnumerationItemType);
+  nsresult                    SetEnumDocShellType(int32_t aEnumerationItemType);
+    
+  nsresult                    First();
+
+protected:
+
+  nsresult                    EnsureDocShellArray();
+  nsresult                    ClearState();
+  
+  nsresult                    BuildDocShellArray(nsTArray<nsWeakPtr>& inItemArray);
+  virtual nsresult            BuildArrayRecursive(nsIDocShellTreeItem* inItem, nsTArray<nsWeakPtr>& inItemArray) = 0;
+    
+protected:
+
+  nsWeakPtr                   mRootItem;      // weak ref!
+  
+  nsTArray<nsWeakPtr>         mItemArray;     // flattened list of items with matching type
+  uint32_t                    mCurIndex;
+  
+  int32_t                     mDocShellType;  // only want shells of this type
+  bool                        mArrayValid;    // is mItemArray up to date?
+
+  const int8_t                mEnumerationDirection;
+};
+
+
+class nsDocShellForwardsEnumerator : public nsDocShellEnumerator
+{
+public:
+
+                              nsDocShellForwardsEnumerator()
+                              : nsDocShellEnumerator(enumerateForwards)
+                              {                              
+                              }
+
+protected:
+
+  virtual nsresult            BuildArrayRecursive(nsIDocShellTreeItem* inItem, nsTArray<nsWeakPtr>& inItemArray);
+
+};
+
+class nsDocShellBackwardsEnumerator : public nsDocShellEnumerator
+{
+public:
+
+                              nsDocShellBackwardsEnumerator()
+                              : nsDocShellEnumerator(enumerateBackwards)
+                              {                              
+                              }
+protected:
+
+  virtual nsresult            BuildArrayRecursive(nsIDocShellTreeItem* inItem, nsTArray<nsWeakPtr>& inItemArray);
+};
+
+#endif // nsDocShellEnumerator_h___