mirror of
https://github.com/classilla/tenfourfox.git
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158 lines
4.6 KiB
C++
158 lines
4.6 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/*
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* A class that computes and caches the indices used for :nth-* pseudo-class
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* matching.
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*/
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#include "nsNthIndexCache.h"
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#include "mozilla/dom/Element.h"
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#include "mozilla/dom/NodeInfoInlines.h"
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nsNthIndexCache::nsNthIndexCache()
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{
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}
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nsNthIndexCache::~nsNthIndexCache()
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{
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}
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void
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nsNthIndexCache::Reset()
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{
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mCaches[0][0].clear();
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mCaches[0][1].clear();
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mCaches[1][0].clear();
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mCaches[1][1].clear();
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}
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inline bool
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nsNthIndexCache::SiblingMatchesElement(nsIContent* aSibling, Element* aElement,
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bool aIsOfType)
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{
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return aSibling->IsElement() &&
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(!aIsOfType ||
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aSibling->NodeInfo()->NameAndNamespaceEquals(aElement->NodeInfo()));
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}
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inline bool
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nsNthIndexCache::IndexDeterminedFromPreviousSibling(nsIContent* aSibling,
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Element* aChild,
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bool aIsOfType,
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bool aIsFromEnd,
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const Cache& aCache,
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int32_t& aResult)
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{
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if (SiblingMatchesElement(aSibling, aChild, aIsOfType)) {
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Cache::Ptr siblingEntry = aCache.lookup(aSibling);
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if (siblingEntry) {
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int32_t siblingIndex = siblingEntry->value();
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NS_ASSERTION(siblingIndex != 0,
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"How can a non-anonymous node have an anonymous sibling?");
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if (siblingIndex > 0) {
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// At this point, aResult is a count of how many elements matching
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// aChild we have seen after aSibling, including aChild itself.
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// |siblingIndex| is the index of aSibling.
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// So if aIsFromEnd, we want |aResult = siblingIndex - aResult| and
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// otherwise we want |aResult = siblingIndex + aResult|.
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aResult = siblingIndex + aResult * (1 - 2 * aIsFromEnd);
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return true;
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}
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}
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++aResult;
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}
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return false;
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}
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int32_t
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nsNthIndexCache::GetNthIndex(Element* aChild, bool aIsOfType,
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bool aIsFromEnd, bool aCheckEdgeOnly)
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{
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NS_ASSERTION(aChild->GetParent(), "caller should check GetParent()");
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if (aChild->IsRootOfAnonymousSubtree()) {
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return 0;
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}
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Cache &cache = mCaches[aIsOfType][aIsFromEnd];
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if (!cache.initialized() && !cache.init()) {
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// Give up and just don't match.
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return 0;
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}
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Cache::AddPtr entry = cache.lookupForAdd(aChild);
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// Default the value to -2 when adding
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if (!entry && !cache.add(entry, aChild, -2)) {
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// No good; don't match.
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return 0;
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}
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int32_t &slot = entry->value();
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if (slot != -2 && (slot != -1 || aCheckEdgeOnly)) {
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return slot;
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}
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int32_t result = 1;
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if (aCheckEdgeOnly) {
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// The caller only cares whether or not the result is 1, so we can
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// stop as soon as we see any other elements that match us.
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if (aIsFromEnd) {
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for (nsIContent *cur = aChild->GetNextSibling();
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cur;
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cur = cur->GetNextSibling()) {
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if (SiblingMatchesElement(cur, aChild, aIsOfType)) {
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result = -1;
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break;
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}
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}
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} else {
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for (nsIContent *cur = aChild->GetPreviousSibling();
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cur;
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cur = cur->GetPreviousSibling()) {
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if (SiblingMatchesElement(cur, aChild, aIsOfType)) {
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result = -1;
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break;
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}
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}
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}
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} else {
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// In the common case, we already have a cached index for one of
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// our previous siblings, so check that first.
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for (nsIContent *cur = aChild->GetPreviousSibling();
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cur;
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cur = cur->GetPreviousSibling()) {
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if (IndexDeterminedFromPreviousSibling(cur, aChild, aIsOfType,
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aIsFromEnd, cache, result)) {
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slot = result;
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return result;
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}
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}
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// Now if aIsFromEnd we lose: need to actually compute our index,
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// since looking at previous siblings wouldn't have told us
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// anything about it. Note that it doesn't make sense to do cache
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// lookups on our following siblings, since chances are the cache
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// is not primed for them.
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if (aIsFromEnd) {
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result = 1;
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for (nsIContent *cur = aChild->GetNextSibling();
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cur;
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cur = cur->GetNextSibling()) {
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if (SiblingMatchesElement(cur, aChild, aIsOfType)) {
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++result;
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}
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}
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}
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}
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slot = result;
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return result;
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}
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