diff -r 000000000000 -r 6474c204b198 dom/xslt/base/txExpandedNameMap.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/xslt/base/txExpandedNameMap.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,105 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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/. */
+
+#include "txExpandedNameMap.h"
+#include "txCore.h"
+
+class txMapItemComparator
+{
+  public:
+    bool Equals(const txExpandedNameMap_base::MapItem& aItem,
+                  const txExpandedName& aKey) const {
+      return aItem.mNamespaceID == aKey.mNamespaceID &&
+             aItem.mLocalName == aKey.mLocalName;
+    }
+};
+
+/**
+ * Adds an item, if an item with this key already exists an error is
+ * returned
+ * @param  aKey   key for item to add
+ * @param  aValue value of item to add
+ * @return errorcode
+ */
+nsresult txExpandedNameMap_base::addItem(const txExpandedName& aKey,
+                                         void* aValue)
+{
+    uint32_t pos = mItems.IndexOf(aKey, 0, txMapItemComparator());
+    if (pos != mItems.NoIndex) {
+        return NS_ERROR_XSLT_ALREADY_SET;
+    }
+
+    MapItem* item = mItems.AppendElement();
+    NS_ENSURE_TRUE(item, NS_ERROR_OUT_OF_MEMORY);
+
+    item->mNamespaceID = aKey.mNamespaceID;
+    item->mLocalName = aKey.mLocalName;
+    item->mValue = aValue;
+
+    return NS_OK;
+}
+
+/**
+ * Sets an item, if an item with this key already exists it is overwritten
+ * with the new value
+ * @param  aKey   key for item to set
+ * @param  aValue value of item to set
+ * @return errorcode
+ */
+nsresult txExpandedNameMap_base::setItem(const txExpandedName& aKey,
+                                         void* aValue,
+                                         void** aOldValue)
+{
+    *aOldValue = nullptr;
+    uint32_t pos = mItems.IndexOf(aKey, 0, txMapItemComparator());
+    if (pos != mItems.NoIndex) {
+        *aOldValue = mItems[pos].mValue;
+        mItems[pos].mValue = aValue;
+        
+        return NS_OK;
+    }
+
+    MapItem* item = mItems.AppendElement();
+    NS_ENSURE_TRUE(item, NS_ERROR_OUT_OF_MEMORY);
+
+    item->mNamespaceID = aKey.mNamespaceID;
+    item->mLocalName = aKey.mLocalName;
+    item->mValue = aValue;
+
+    return NS_OK;
+}
+
+/**
+ * Gets an item
+ * @param  aKey  key for item to get
+ * @return item with specified key, or null if no such item exists
+ */
+void* txExpandedNameMap_base::getItem(const txExpandedName& aKey) const
+{
+    uint32_t pos = mItems.IndexOf(aKey, 0, txMapItemComparator());
+    if (pos != mItems.NoIndex) {
+        return mItems[pos].mValue;
+    }
+
+    return nullptr;
+}
+
+/**
+ * Removes an item, deleting it if the map owns the values
+ * @param  aKey  key for item to remove
+ * @return item with specified key, or null if it has been deleted
+ *         or no such item exists
+ */
+void* txExpandedNameMap_base::removeItem(const txExpandedName& aKey)
+{
+    void* value = nullptr;
+    uint32_t pos = mItems.IndexOf(aKey, 0, txMapItemComparator());
+    if (pos != mItems.NoIndex) {
+        value = mItems[pos].mValue;
+        mItems.RemoveElementAt(pos);
+    }
+
+    return value;
+}