Mozilla/mozilla/content/base/src/nsDOMAttribute.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Communicator client code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
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 * ***** END LICENSE BLOCK ***** */

/*
 * Implementation of DOM Core's nsIDOMAttr node.
 */

#include "nsDOMAttribute.h"
#include "nsGenericElement.h"
#include "nsIContent.h"
#include "nsITextContent.h"
#include "nsINameSpaceManager.h"
#include "nsDOMError.h"
#include "nsContentUtils.h"
#include "nsUnicharUtils.h"
#include "nsDOMString.h"
#include "nsIDocument.h"
#include "nsIDOMDocument.h"
#include "nsIDOM3Attr.h"
#include "nsIDOMUserDataHandler.h"
#include "nsITextContent.h"
#include "nsEventDispatcher.h"
#include "nsGkAtoms.h"
#include "nsCOMArray.h"

//----------------------------------------------------------------------
PRBool nsDOMAttribute::sInitialized;

nsDOMAttribute::nsDOMAttribute(nsDOMAttributeMap *aAttrMap,
                               nsINodeInfo       *aNodeInfo,
                               const nsAString   &aValue)
  : nsIAttribute(aAttrMap, aNodeInfo), mValue(aValue), mChildList(nsnull)
{
  NS_ABORT_IF_FALSE(mNodeInfo, "We must get a nodeinfo here!");


  // We don't add a reference to our content. It will tell us
  // to drop our reference when it goes away.
}

nsDOMAttribute::~nsDOMAttribute()
{
  if (mChildList) {
    mChildList->DropReference();
    NS_RELEASE(mChildList);
  }
}


// QueryInterface implementation for nsDOMAttribute
NS_INTERFACE_MAP_BEGIN(nsDOMAttribute)
  NS_INTERFACE_MAP_ENTRY(nsIDOMAttr)
  NS_INTERFACE_MAP_ENTRY(nsIAttribute)
  NS_INTERFACE_MAP_ENTRY(nsINode)
  NS_INTERFACE_MAP_ENTRY(nsIDOMGCParticipant)
  NS_INTERFACE_MAP_ENTRY(nsIDOMNode)
  NS_INTERFACE_MAP_ENTRY(nsIDOM3Node)
  NS_INTERFACE_MAP_ENTRY(nsIDOM3Attr)
  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIDOMAttr)
  NS_INTERFACE_MAP_ENTRY_CONTENT_CLASSINFO(Attr)
NS_INTERFACE_MAP_END


NS_IMPL_ADDREF(nsDOMAttribute)
NS_IMPL_RELEASE(nsDOMAttribute)

// nsIDOMGCParticipant methods
nsIDOMGCParticipant*
nsDOMAttribute::GetSCCIndex()
{
  nsIContent *owner = GetContentInternal();

  return owner ? owner->GetSCCIndex() : this;
}

void
nsDOMAttribute::AppendReachableList(nsCOMArray<nsIDOMGCParticipant>& aArray)
{
  NS_ASSERTION(GetContentInternal() == nsnull,
               "shouldn't be an SCC index if we're in an element");

  // This node is the root of a subtree that's been removed from the
  // document (since AppendReachableList is only called on SCC index
  // nodes).  The document is reachable from it (through
  // .ownerDocument), but it's not reachable from the document.
  aArray.AppendObject(GetOwnerDoc());
}

void
nsDOMAttribute::SetMap(nsDOMAttributeMap *aMap)
{
  if (mAttrMap && !aMap && sInitialized) {
    // We're breaking a relationship with content and not getting a new one,
    // need to locally cache value. GetValue() does that.
    GetValue(mValue);
  }
  
  mAttrMap = aMap;
}

nsIContent*
nsDOMAttribute::GetContent() const
{
  return GetContentInternal();
}

nsresult
nsDOMAttribute::SetOwnerDocument(nsIDocument* aDocument)
{
  NS_ASSERTION(aDocument, "Missing document");

  nsIDocument *doc = GetOwnerDoc();
  NS_ASSERTION(doc != aDocument, "bad call to nsDOMAttribute::SetOwnerDocument");
  if (doc) {
    doc->PropertyTable()->DeleteAllPropertiesFor(this);
  }

  nsCOMPtr<nsINodeInfo> newNodeInfo;
  nsresult rv = aDocument->NodeInfoManager()->
    GetNodeInfo(mNodeInfo->NameAtom(), mNodeInfo->GetPrefixAtom(),
                mNodeInfo->NamespaceID(), getter_AddRefs(newNodeInfo));
  NS_ENSURE_SUCCESS(rv, rv);
  NS_ASSERTION(newNodeInfo, "GetNodeInfo lies");
  mNodeInfo.swap(newNodeInfo);

  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetName(nsAString& aName)
{
  mNodeInfo->GetQualifiedName(aName);
  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetValue(nsAString& aValue)
{
  nsIContent* content = GetContentInternal();
  if (content) {
    content->GetAttr(mNodeInfo->NamespaceID(), mNodeInfo->NameAtom(), aValue);
  }
  else {
    aValue = mValue;
  }

  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::SetValue(const nsAString& aValue)
{
  nsresult rv = NS_OK;
  nsIContent* content = GetContentInternal();
  if (content) {
    rv = content->SetAttr(mNodeInfo->NamespaceID(),
                          mNodeInfo->NameAtom(),
                          mNodeInfo->GetPrefixAtom(),
                          aValue,
                          PR_TRUE);
  }
  else {
    mValue = aValue;
  }

  return rv;
}

NS_IMETHODIMP
nsDOMAttribute::GetSpecified(PRBool* aSpecified)
{
  NS_ENSURE_ARG_POINTER(aSpecified);

  nsIContent* content = GetContentInternal();
  *aSpecified = content && content->HasAttr(mNodeInfo->NamespaceID(),
                                            mNodeInfo->NameAtom());

  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetOwnerElement(nsIDOMElement** aOwnerElement)
{
  NS_ENSURE_ARG_POINTER(aOwnerElement);

  nsIContent* content = GetContentInternal();
  if (content) {
    return CallQueryInterface(content, aOwnerElement);
  }

  *aOwnerElement = nsnull;

  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetNodeName(nsAString& aNodeName)
{
  return GetName(aNodeName);
}

NS_IMETHODIMP
nsDOMAttribute::GetNodeValue(nsAString& aNodeValue)
{
  return GetValue(aNodeValue);
}

NS_IMETHODIMP
nsDOMAttribute::SetNodeValue(const nsAString& aNodeValue)
{
  return SetValue(aNodeValue);
}

NS_IMETHODIMP
nsDOMAttribute::GetNodeType(PRUint16* aNodeType)
{
  NS_ENSURE_ARG_POINTER(aNodeType);

  *aNodeType = (PRUint16)nsIDOMNode::ATTRIBUTE_NODE;
  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetParentNode(nsIDOMNode** aParentNode)
{
  NS_ENSURE_ARG_POINTER(aParentNode);

  *aParentNode = nsnull;
  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetChildNodes(nsIDOMNodeList** aChildNodes)
{
  if (!mChildList) {
    mChildList = new nsAttributeChildList(this);
    NS_ENSURE_TRUE(mChildList, NS_ERROR_OUT_OF_MEMORY);

    NS_ADDREF(mChildList);
  }

  return CallQueryInterface(mChildList, aChildNodes);
}

NS_IMETHODIMP
nsDOMAttribute::HasChildNodes(PRBool* aHasChildNodes)
{
  PRBool hasChild;
  nsresult rv = EnsureChildState(PR_FALSE, hasChild);
  NS_ENSURE_SUCCESS(rv, rv);

  *aHasChildNodes = hasChild;

  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::HasAttributes(PRBool* aHasAttributes)
{
  NS_ENSURE_ARG_POINTER(aHasAttributes);

  *aHasAttributes = PR_FALSE;

  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetFirstChild(nsIDOMNode** aFirstChild)
{
  *aFirstChild = nsnull;

  PRBool hasChild;
  nsresult rv = EnsureChildState(PR_TRUE, hasChild);
  NS_ENSURE_SUCCESS(rv, rv);

  if (mChild) {
    CallQueryInterface(mChild, aFirstChild);
  }
  
  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetLastChild(nsIDOMNode** aLastChild)
{
  return GetFirstChild(aLastChild);
}

NS_IMETHODIMP
nsDOMAttribute::GetPreviousSibling(nsIDOMNode** aPreviousSibling)
{
  NS_ENSURE_ARG_POINTER(aPreviousSibling);

  *aPreviousSibling = nsnull;
  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetNextSibling(nsIDOMNode** aNextSibling)
{
  NS_ENSURE_ARG_POINTER(aNextSibling);

  *aNextSibling = nsnull;
  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetAttributes(nsIDOMNamedNodeMap** aAttributes)
{
  NS_ENSURE_ARG_POINTER(aAttributes);

  *aAttributes = nsnull;
  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::InsertBefore(nsIDOMNode* aNewChild, nsIDOMNode* aRefChild, nsIDOMNode** aReturn)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsDOMAttribute::ReplaceChild(nsIDOMNode* aNewChild, nsIDOMNode* aOldChild, nsIDOMNode** aReturn)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsDOMAttribute::RemoveChild(nsIDOMNode* aOldChild, nsIDOMNode** aReturn)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsDOMAttribute::AppendChild(nsIDOMNode* aNewChild, nsIDOMNode** aReturn)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsDOMAttribute::CloneNode(PRBool aDeep, nsIDOMNode** aReturn)
{
  *aReturn = nsnull;

  nsAutoString value;
  GetValue(value);

  nsCOMPtr<nsIDOMNode> newAttr = new nsDOMAttribute(nsnull, mNodeInfo, value);
  if (!newAttr) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  nsIDocument *document = GetOwnerDoc();
  if (document) {
    // XXX For now, nsDOMAttribute has only one child. We need to notify about
    //     cloning it, so we force creation here.
    nsCOMPtr<nsIDOMNode> child;
    GetFirstChild(getter_AddRefs(child));
    nsCOMPtr<nsINode> childNode = do_QueryInterface(child);
    if (childNode && childNode->HasProperties()) {
      nsCOMPtr<nsIDOMNode> newChild;
      newAttr->GetFirstChild(getter_AddRefs(newChild));
      if (newChild) {
        nsContentUtils::CallUserDataHandler(document,
                                            nsIDOMUserDataHandler::NODE_CLONED,
                                            childNode, child, newChild);
      }
    }

    if (HasProperties()) {
      nsContentUtils::CallUserDataHandler(document,
                                          nsIDOMUserDataHandler::NODE_CLONED,
                                          this, this, newAttr);
    }
  }

  newAttr.swap(*aReturn);

  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetOwnerDocument(nsIDOMDocument** aOwnerDocument)
{
  *aOwnerDocument = nsnull;

  nsIDocument *document = GetOwnerDoc();

  return document ? CallQueryInterface(document, aOwnerDocument) : NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetNamespaceURI(nsAString& aNamespaceURI)
{
  return mNodeInfo->GetNamespaceURI(aNamespaceURI);
}

NS_IMETHODIMP
nsDOMAttribute::GetPrefix(nsAString& aPrefix)
{
  mNodeInfo->GetPrefix(aPrefix);
  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::SetPrefix(const nsAString& aPrefix)
{
  // XXX: Validate the prefix string!

  nsCOMPtr<nsINodeInfo> newNodeInfo;
  nsCOMPtr<nsIAtom> prefix;

  if (!aPrefix.IsEmpty()) {
    prefix = do_GetAtom(aPrefix);
    if (!prefix) {
      return NS_ERROR_OUT_OF_MEMORY;
    }
  }

  if (!nsContentUtils::IsValidNodeName(mNodeInfo->NameAtom(), prefix,
                                       mNodeInfo->NamespaceID())) {
    return NS_ERROR_DOM_NAMESPACE_ERR;
  }

  nsresult rv = nsContentUtils::PrefixChanged(mNodeInfo, prefix,
                                              getter_AddRefs(newNodeInfo));
  NS_ENSURE_SUCCESS(rv, rv);

  nsIContent* content = GetContentInternal();
  if (content) {
    nsIAtom *name = mNodeInfo->NameAtom();
    PRInt32 nameSpaceID = mNodeInfo->NamespaceID();

    nsAutoString tmpValue;
    if (content->GetAttr(nameSpaceID, name, tmpValue)) {
      content->UnsetAttr(nameSpaceID, name, PR_TRUE);

      content->SetAttr(newNodeInfo->NamespaceID(), newNodeInfo->NameAtom(),
                       newNodeInfo->GetPrefixAtom(), tmpValue, PR_TRUE);
    }
  }

  newNodeInfo.swap(mNodeInfo);

  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetLocalName(nsAString& aLocalName)
{
  mNodeInfo->GetLocalName(aLocalName);
  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::Normalize()
{
  // Nothing to do here
  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::IsSupported(const nsAString& aFeature,
                            const nsAString& aVersion,
                            PRBool* aReturn)
{
  return nsGenericElement::InternalIsSupported(NS_STATIC_CAST(nsIDOMAttr*, this), 
                                               aFeature, aVersion, aReturn);
}

NS_IMETHODIMP
nsDOMAttribute::GetBaseURI(nsAString &aURI)
{
  aURI.Truncate();
  nsresult rv = NS_OK;
  nsCOMPtr<nsIDOM3Node> node(do_QueryInterface(GetContentInternal()));
  if (node)
    rv = node->GetBaseURI(aURI);
  return rv;
}

NS_IMETHODIMP
nsDOMAttribute::CompareDocumentPosition(nsIDOMNode* aOther,
                                        PRUint16* aReturn)
{
  NS_ENSURE_ARG_POINTER(aOther);

  nsCOMPtr<nsINode> other = do_QueryInterface(aOther);
  NS_ENSURE_TRUE(other, NS_ERROR_DOM_NOT_SUPPORTED_ERR);

  *aReturn = nsContentUtils::ComparePosition(other, this);
  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::IsSameNode(nsIDOMNode* aOther,
                           PRBool* aReturn)
{
  NS_ASSERTION(aReturn, "IsSameNode() called with aReturn == nsnull!");
  
  *aReturn = SameCOMIdentity(NS_STATIC_CAST(nsIDOMNode*, this), aOther);

  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::IsEqualNode(nsIDOMNode* aOther,
                            PRBool* aReturn)
{
  NS_NOTYETIMPLEMENTED("nsDocument::IsEqualNode()");

  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsDOMAttribute::IsDefaultNamespace(const nsAString& aNamespaceURI,
                                   PRBool* aReturn)
{
  *aReturn = PR_FALSE;
  nsCOMPtr<nsIDOM3Node> node(do_QueryInterface(GetContentInternal()));
  if (node) {
    return node->IsDefaultNamespace(aNamespaceURI, aReturn);
  }
  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetTextContent(nsAString &aTextContent)
{
  return GetNodeValue(aTextContent);
}

NS_IMETHODIMP
nsDOMAttribute::SetTextContent(const nsAString& aTextContent)
{
  return SetNodeValue(aTextContent);
}


NS_IMETHODIMP
nsDOMAttribute::GetFeature(const nsAString& aFeature,
                           const nsAString& aVersion,
                           nsISupports** aReturn)
{
  return nsGenericElement::InternalGetFeature(NS_STATIC_CAST(nsIDOMAttr*, this), 
                                              aFeature, aVersion, aReturn);
}

NS_IMETHODIMP
nsDOMAttribute::SetUserData(const nsAString& aKey, nsIVariant* aData,
                            nsIDOMUserDataHandler* aHandler,
                            nsIVariant** aResult)
{
  nsCOMPtr<nsIAtom> key = do_GetAtom(aKey);
  if (!key) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  return nsContentUtils::SetUserData(this, key, aData, aHandler, aResult);
}

NS_IMETHODIMP
nsDOMAttribute::GetUserData(const nsAString& aKey, nsIVariant** aResult)
{
  nsIDocument *document = GetOwnerDoc();
  NS_ENSURE_TRUE(document, NS_ERROR_FAILURE);

  nsCOMPtr<nsIAtom> key = do_GetAtom(aKey);
  if (!key) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  *aResult = NS_STATIC_CAST(nsIVariant*, GetProperty(DOM_USER_DATA, key));
  NS_IF_ADDREF(*aResult);

  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetIsId(PRBool* aReturn)
{
  nsIContent* content = GetContentInternal();
  if (!content)
  {
    *aReturn = PR_FALSE;
    return NS_OK;
  }

  nsIAtom* idAtom = content->GetIDAttributeName();
  if (!idAtom)
  {
    *aReturn = PR_FALSE;
    return NS_OK;
  }

  *aReturn = mNodeInfo->Equals(idAtom, kNameSpaceID_None);
  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::GetSchemaTypeInfo(nsIDOM3TypeInfo** aReturn)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsDOMAttribute::LookupPrefix(const nsAString& aNamespaceURI,
                             nsAString& aPrefix)
{
  nsCOMPtr<nsIDOM3Node> node(do_QueryInterface(GetContentInternal()));
  if (node)
    return node->LookupPrefix(aNamespaceURI, aPrefix);

  SetDOMStringToNull(aPrefix);
  return NS_OK;
}

NS_IMETHODIMP
nsDOMAttribute::LookupNamespaceURI(const nsAString& aNamespacePrefix,
                                   nsAString& aNamespaceURI)
{
  nsCOMPtr<nsIDOM3Node> node(do_QueryInterface(GetContentInternal()));
  if (node)
    return node->LookupNamespaceURI(aNamespacePrefix, aNamespaceURI);

  SetDOMStringToNull(aNamespaceURI);
  return NS_OK;
}

PRBool
nsDOMAttribute::IsNodeOfType(PRUint32 aFlags) const
{
    return !(aFlags & ~eATTRIBUTE);
}

PRUint32
nsDOMAttribute::GetChildCount() const
{
  PRBool hasChild;
  EnsureChildState(PR_FALSE, hasChild);

  return hasChild ? 1 : 0;
}

nsIContent *
nsDOMAttribute::GetChildAt(PRUint32 aIndex) const
{
  // Don't need to check result of EnsureChildState since mChild will be null.
  PRBool hasChild;
  EnsureChildState(PR_TRUE, hasChild);

  return aIndex == 0 && hasChild ? mChild.get() : nsnull;
}
  
PRInt32
nsDOMAttribute::IndexOf(nsINode* aPossibleChild) const
{
  // No need to call EnsureChildState here. If we don't already have a child
  // then aPossibleChild can't possibly be our child.
  if (!aPossibleChild || aPossibleChild != mChild) {
    return -1;
  }

  PRBool hasChild;
  EnsureChildState(PR_FALSE, hasChild);
  return hasChild ? 0 : -1;
}

nsresult
nsDOMAttribute::InsertChildAt(nsIContent* aKid, PRUint32 aIndex,
                              PRBool aNotify)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

nsresult
nsDOMAttribute::AppendChildTo(nsIContent* aKid, PRBool aNotify)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

nsresult
nsDOMAttribute::RemoveChildAt(PRUint32 aIndex, PRBool aNotify)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

nsresult
nsDOMAttribute::PreHandleEvent(nsEventChainPreVisitor& aVisitor)
{
  // We don't support event dispatching to attributes yet.
  aVisitor.mCanHandle = PR_FALSE;
  return NS_OK;
}

nsresult
nsDOMAttribute::PostHandleEvent(nsEventChainPostVisitor& aVisitor)
{
  return NS_OK;
}

nsresult
nsDOMAttribute::DispatchDOMEvent(nsEvent* aEvent, nsIDOMEvent* aDOMEvent,
                                 nsPresContext* aPresContext,
                                 nsEventStatus* aEventStatus)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

nsresult
nsDOMAttribute::EnsureChildState(PRBool aSetText, PRBool &aHasChild) const
{
  aHasChild = PR_FALSE;

  nsDOMAttribute* mutableThis = NS_CONST_CAST(nsDOMAttribute*, this);

  nsAutoString value;
  mutableThis->GetValue(value);

  if (!mChild && !value.IsEmpty()) {
    nsresult rv = NS_NewTextNode(getter_AddRefs(mutableThis->mChild),
                                 mNodeInfo->NodeInfoManager());
    NS_ENSURE_SUCCESS(rv, rv);

    // XXX We should be setting |this| as the parent of the textnode!
  }

  aHasChild = !value.IsEmpty();

  if (aSetText && aHasChild) {
    mChild->SetText(value, PR_TRUE);
  }

  return NS_OK;
}

void
nsDOMAttribute::Initialize()
{
  sInitialized = PR_TRUE;
}

void
nsDOMAttribute::Shutdown()
{
  sInitialized = PR_FALSE;
}

//----------------------------------------------------------------------

nsAttributeChildList::nsAttributeChildList(nsDOMAttribute* aAttribute)
{
  // Don't increment the reference count. The attribute will tell
  // us when it's going away
  mAttribute = aAttribute;
}

nsAttributeChildList::~nsAttributeChildList()
{
}

NS_IMETHODIMP
nsAttributeChildList::GetLength(PRUint32* aLength)
{
  *aLength = mAttribute ? mAttribute->GetChildCount() : 0;

  return NS_OK;
}

NS_IMETHODIMP
nsAttributeChildList::Item(PRUint32 aIndex, nsIDOMNode** aReturn)
{
  *aReturn = nsnull;
  if (mAttribute && 0 == aIndex) {
    mAttribute->GetFirstChild(aReturn);
  }

  return NS_OK;
}

void
nsAttributeChildList::DropReference()
{
  mAttribute = nsnull;
}