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/*
* Copyright (C) 2012 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "core/css/invalidation/StyleSheetInvalidationAnalysis.h"
#include "core/css/CSSSelectorList.h"
#include "core/css/StyleRuleImport.h"
#include "core/css/StyleSheetContents.h"
#include "core/dom/ContainerNode.h"
#include "core/dom/Document.h"
#include "core/dom/ElementTraversal.h"
#include "core/dom/shadow/ShadowRoot.h"
#include "core/html/HTMLStyleElement.h"
namespace WebCore {
StyleSheetInvalidationAnalysis::StyleSheetInvalidationAnalysis(const WillBeHeapVector<RawPtrWillBeMember<StyleSheetContents> >& sheets)
: m_dirtiesAllStyle(false)
{
for (unsigned i = 0; i < sheets.size() && !m_dirtiesAllStyle; ++i)
analyzeStyleSheet(sheets[i]);
}
static bool determineSelectorScopes(const CSSSelectorList& selectorList, HashSet<StringImpl*>& idScopes, HashSet<StringImpl*>& classScopes)
{
for (const CSSSelector* selector = selectorList.first(); selector; selector = CSSSelectorList::next(*selector)) {
const CSSSelector* scopeSelector = 0;
// This picks the widest scope, not the narrowest, to minimize the number of found scopes.
for (const CSSSelector* current = selector; current; current = current->tagHistory()) {
// Prefer ids over classes.
if (current->match() == CSSSelector::Id)
scopeSelector = current;
else if (current->match() == CSSSelector::Class && (!scopeSelector || scopeSelector->match() != CSSSelector::Id))
scopeSelector = current;
CSSSelector::Relation relation = current->relation();
// FIXME: it would be better to use setNeedsStyleRecalc for all shadow hosts matching
// scopeSelector. Currently requests full style recalc.
if (relation == CSSSelector::ShadowDeep || relation == CSSSelector::ShadowPseudo)
return false;
if (relation != CSSSelector::Descendant && relation != CSSSelector::Child && relation != CSSSelector::SubSelector)
break;
}
if (!scopeSelector)
return false;
ASSERT(scopeSelector->match() == CSSSelector::Class || scopeSelector->match() == CSSSelector::Id);
if (scopeSelector->match() == CSSSelector::Id)
idScopes.add(scopeSelector->value().impl());
else
classScopes.add(scopeSelector->value().impl());
}
return true;
}
static bool hasDistributedRule(StyleSheetContents* styleSheetContents)
{
const WillBeHeapVector<RefPtrWillBeMember<StyleRuleBase> >& rules = styleSheetContents->childRules();
for (unsigned i = 0; i < rules.size(); i++) {
const StyleRuleBase* rule = rules[i].get();
if (!rule->isStyleRule())
continue;
const StyleRule* styleRule = toStyleRule(rule);
const CSSSelectorList& selectorList = styleRule->selectorList();
for (size_t selectorIndex = 0; selectorIndex != kNotFound; selectorIndex = selectorList.indexOfNextSelectorAfter(selectorIndex)) {
if (selectorList.hasShadowDistributedAt(selectorIndex))
return true;
}
}
return false;
}
static Node* determineScopingNodeForStyleInShadow(HTMLStyleElement* ownerElement, StyleSheetContents* styleSheetContents)
{
ASSERT(ownerElement && ownerElement->isInShadowTree());
if (hasDistributedRule(styleSheetContents)) {
ContainerNode* scope = ownerElement;
do {
scope = scope->containingShadowRoot()->shadowHost();
} while (scope->isInShadowTree());
return scope;
}
return ownerElement->containingShadowRoot()->shadowHost();
}
static bool ruleAdditionMightRequireDocumentStyleRecalc(StyleRuleBase* rule)
{
// This funciton is conservative. We only return false when we know that
// the added @rule can't require style recalcs.
switch (rule->type()) {
case StyleRule::Import: // Whatever we import should do its own analysis, we don't need to invalidate the document here!
case StyleRule::Keyframes: // Keyframes never cause style invalidations and are handled during sheet insertion.
case StyleRule::Page: // Page rules apply only during printing, we force a full-recalc before printing.
return false;
case StyleRule::Media: // If the media rule doesn't apply, we could avoid recalc.
case StyleRule::FontFace: // If the fonts aren't in use, we could avoid recalc.
case StyleRule::Supports: // If we evaluated the supports-clause we could avoid recalc.
case StyleRule::Viewport: // If the viewport doesn't match, we could avoid recalcing.
// FIXME: Unclear if any of the rest need to cause style recalc:
case StyleRule::Filter:
return true;
// These should all be impossible to reach:
case StyleRule::Unknown:
case StyleRule::Charset:
case StyleRule::Keyframe:
case StyleRule::Style:
break;
}
ASSERT_NOT_REACHED();
return true;
}
void StyleSheetInvalidationAnalysis::analyzeStyleSheet(StyleSheetContents* styleSheetContents)
{
ASSERT(!styleSheetContents->isLoading());
// See if all rules on the sheet are scoped to some specific ids or classes.
// Then test if we actually have any of those in the tree at the moment.
const WillBeHeapVector<RefPtrWillBeMember<StyleRuleImport> >& importRules = styleSheetContents->importRules();
for (unsigned i = 0; i < importRules.size(); ++i) {
if (!importRules[i]->styleSheet())
continue;
analyzeStyleSheet(importRules[i]->styleSheet());
if (m_dirtiesAllStyle)
return;
}
if (styleSheetContents->hasSingleOwnerNode()) {
Node* ownerNode = styleSheetContents->singleOwnerNode();
if (isHTMLStyleElement(ownerNode) && toHTMLStyleElement(*ownerNode).isInShadowTree()) {
m_scopingNodes.append(determineScopingNodeForStyleInShadow(toHTMLStyleElement(ownerNode), styleSheetContents));
return;
}
}
const WillBeHeapVector<RefPtrWillBeMember<StyleRuleBase> >& rules = styleSheetContents->childRules();
for (unsigned i = 0; i < rules.size(); i++) {
StyleRuleBase* rule = rules[i].get();
if (!rule->isStyleRule()) {
if (ruleAdditionMightRequireDocumentStyleRecalc(rule)) {
m_dirtiesAllStyle = true;
return;
}
continue;
}
StyleRule* styleRule = toStyleRule(rule);
if (!determineSelectorScopes(styleRule->selectorList(), m_idScopes, m_classScopes)) {
m_dirtiesAllStyle = true;
return;
}
}
}
static bool elementMatchesSelectorScopes(const Element* element, const HashSet<StringImpl*>& idScopes, const HashSet<StringImpl*>& classScopes)
{
if (!idScopes.isEmpty() && element->hasID() && idScopes.contains(element->idForStyleResolution().impl()))
return true;
if (classScopes.isEmpty() || !element->hasClass())
return false;
const SpaceSplitString& classNames = element->classNames();
for (unsigned i = 0; i < classNames.size(); ++i) {
if (classScopes.contains(classNames[i].impl()))
return true;
}
return false;
}
void StyleSheetInvalidationAnalysis::invalidateStyle(Document& document)
{
ASSERT(!m_dirtiesAllStyle);
if (!m_scopingNodes.isEmpty()) {
for (unsigned i = 0; i < m_scopingNodes.size(); ++i)
m_scopingNodes.at(i)->setNeedsStyleRecalc(SubtreeStyleChange);
}
if (m_idScopes.isEmpty() && m_classScopes.isEmpty())
return;
Element* element = ElementTraversal::firstWithin(document);
while (element) {
if (elementMatchesSelectorScopes(element, m_idScopes, m_classScopes)) {
element->setNeedsStyleRecalc(SubtreeStyleChange);
// The whole subtree is now invalidated, we can skip to the next sibling.
element = ElementTraversal::nextSkippingChildren(*element);
continue;
}
element = ElementTraversal::next(*element);
}
}
}
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