gecko-dev/layout/style/nsNthIndexCache.cpp

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/* -*- 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.org code.
*
* The Initial Developer of the Original Code is
* Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2011
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Boris Zbarsky <bzbarsky@mit.edu> (original author)
* L. David Baron <dbaron@dbaron.org>
*
* 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
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* A class that computes and caches the indices used for :nth-* pseudo-class
* matching.
*/
#include "nsNthIndexCache.h"
#include "nsIContent.h"
nsNthIndexCache::nsNthIndexCache()
{
}
nsNthIndexCache::~nsNthIndexCache()
{
}
void
nsNthIndexCache::Reset()
{
mCache.clear();
}
inline bool
nsNthIndexCache::SiblingMatchesElement(nsIContent* aSibling, Element* aElement,
PRBool aIsOfType)
{
return aSibling->IsElement() &&
(!aIsOfType ||
aSibling->NodeInfo()->NameAndNamespaceEquals(aElement->NodeInfo()));
}
inline bool
nsNthIndexCache::IndexDetermined(nsIContent* aSibling, Element* aChild,
PRBool aIsOfType, PRBool aIsFromEnd,
PRBool aCheckEdgeOnly, PRInt32& aResult)
{
if (SiblingMatchesElement(aSibling, aChild, aIsOfType)) {
if (aCheckEdgeOnly) {
// The caller only cares whether or not the result is 1, and we
// now know it's not.
aResult = -1;
return true;
}
Cache::Ptr siblingEntry = mCache.lookup(aSibling);
if (siblingEntry) {
PRInt32 siblingIndex = siblingEntry->value.mNthIndices[aIsOfType][aIsFromEnd];
NS_ASSERTION(siblingIndex != 0,
"How can a non-anonymous node have an anonymous sibling?");
if (siblingIndex > 0) {
aResult = siblingIndex + 1;
return true;
}
}
++aResult;
}
return false;
}
PRInt32
nsNthIndexCache::GetNthIndex(Element* aChild, PRBool aIsOfType,
PRBool aIsFromEnd, PRBool aCheckEdgeOnly)
{
NS_ASSERTION(aChild->GetParent(), "caller should check GetParent()");
if (aChild->IsRootOfAnonymousSubtree()) {
return 0;
}
if (!mCache.initialized() && !mCache.init()) {
// Give up and just don't match.
return 0;
}
Cache::AddPtr entry = mCache.lookupForAdd(aChild);
if (!entry && !mCache.add(entry, aChild)) {
// No good; don't match.
return 0;
}
PRInt32 &slot = entry->value.mNthIndices[aIsOfType][aIsFromEnd];
if (slot != -2 && (slot != -1 || aCheckEdgeOnly)) {
return slot;
}
PRInt32 result = 1;
if (aIsFromEnd) {
for (nsIContent *cur = aChild->GetNextSibling();
cur;
cur = cur->GetNextSibling()) {
// It doesn't make sense to do cache lookups for siblings when
// aIsFromEnd. In general, the cache will only be primed for
// things that are _before_ us in the DOM.
if (SiblingMatchesElement(cur, aChild, aIsOfType)) {
if (aCheckEdgeOnly) {
// The caller only cares whether or not the result is 1, and we
// now know it's not.
result = -1;
break;
}
++result;
}
}
} else {
for (nsIContent *cur = aChild->GetPreviousSibling();
cur;
cur = cur->GetPreviousSibling()) {
if (IndexDetermined(cur, aChild, aIsOfType, aIsFromEnd, aCheckEdgeOnly,
result)) {
break;
}
}
}
slot = result;
return result;
}