cssstyleselector.cpp

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    if (!rules)
        return;

    for (CSSRuleData* d = rules->first(); d; d = d->next()) {
        CSSStyleRule* rule = d->rule();
        const AtomicString& localName = m_element->localName();
        const AtomicString& selectorLocalName = d->selector()->m_tag.localName();
        if ((localName == selectorLocalName || selectorLocalName == starAtom) && checkSelector(d->selector())) {
            // If the rule has no properties to apply, then ignore it.
            CSSMutableStyleDeclaration* decl = rule->declaration();
            if (!decl || !decl->length())
                continue;
            
            // If we're matching normal rules, set a pseudo bit if 
            // we really just matched a pseudo-element.
            if (m_dynamicPseudo != NOPSEUDO && m_checker.m_pseudoStyle == NOPSEUDO) {
                if (m_checker.m_collectRulesOnly)
                    return;
                if (m_dynamicPseudo < FIRST_INTERNAL_PSEUDOID)
                    m_style->setHasPseudoStyle(m_dynamicPseudo);
            } else {
                // Update our first/last rule indices in the matched rules array.
                lastRuleIndex = m_matchedDecls.size() + m_matchedRules.size();
                if (firstRuleIndex == -1)
                    firstRuleIndex = lastRuleIndex;

                // Add this rule to our list of matched rules.
                addMatchedRule(d);
            }
        }
    }
}

static bool operator >(CSSRuleData& r1, CSSRuleData& r2)
{
    int spec1 = r1.selector()->specificity();
    int spec2 = r2.selector()->specificity();
    return (spec1 == spec2) ? r1.position() > r2.position() : spec1 > spec2; 
}
    
static bool operator <=(CSSRuleData& r1, CSSRuleData& r2)
{
    return !(r1 > r2);
}

void CSSStyleSelector::sortMatchedRules(unsigned start, unsigned end)
{
    if (start >= end || (end - start == 1))
        return; // Sanity check.

    if (end - start <= 6) {
        // Apply a bubble sort for smaller lists.
        for (unsigned i = end - 1; i > start; i--) {
            bool sorted = true;
            for (unsigned j = start; j < i; j++) {
                CSSRuleData* elt = m_matchedRules[j];
                CSSRuleData* elt2 = m_matchedRules[j + 1];
                if (*elt > *elt2) {
                    sorted = false;
                    m_matchedRules[j] = elt2;
                    m_matchedRules[j + 1] = elt;
                }
            }
            if (sorted)
                return;
        }
        return;
    }

    // Peform a merge sort for larger lists.
    unsigned mid = (start + end) / 2;
    sortMatchedRules(start, mid);
    sortMatchedRules(mid, end);
    
    CSSRuleData* elt = m_matchedRules[mid - 1];
    CSSRuleData* elt2 = m_matchedRules[mid];
    
    // Handle the fast common case (of equal specificity).  The list may already
    // be completely sorted.
    if (*elt <= *elt2)
        return;
    
    // We have to merge sort.  Ensure our merge buffer is big enough to hold
    // all the items.
    Vector<CSSRuleData*> rulesMergeBuffer;
    rulesMergeBuffer.reserveInitialCapacity(end - start); 

    unsigned i1 = start;
    unsigned i2 = mid;
    
    elt = m_matchedRules[i1];
    elt2 = m_matchedRules[i2];
    
    while (i1 < mid || i2 < end) {
        if (i1 < mid && (i2 == end || *elt <= *elt2)) {
            rulesMergeBuffer.append(elt);
            if (++i1 < mid)
                elt = m_matchedRules[i1];
        } else {
            rulesMergeBuffer.append(elt2);
            if (++i2 < end)
                elt2 = m_matchedRules[i2];
        }
    }
    
    for (unsigned i = start; i < end; i++)
        m_matchedRules[i] = rulesMergeBuffer[i - start];
}

void CSSStyleSelector::initElementAndPseudoState(Element* e)
{
    m_element = e;
    if (m_element && m_element->isStyledElement())
        m_styledElement = static_cast<StyledElement*>(m_element);
    else
        m_styledElement = 0;
    pseudoState = PseudoUnknown;
}

void CSSStyleSelector::initForStyleResolve(Element* e, RenderStyle* parentStyle, PseudoId pseudoID)
{
    m_checker.m_pseudoStyle = pseudoID;

    m_parentNode = e ? e->parentNode() : 0;

#if ENABLE(SVG)
    if (!m_parentNode && e && e->isSVGElement() && e->isShadowNode())
        m_parentNode = e->shadowParentNode();
#endif

    if (parentStyle)
        m_parentStyle = parentStyle;
    else
        m_parentStyle = m_parentNode ? m_parentNode->renderStyle() : 0;

    m_style = 0;

    m_matchedDecls.clear();

    m_ruleList = 0;

    m_fontDirty = false;
}

static inline const AtomicString* linkAttribute(Node* node)
{
    if (!node->isLink())
        return 0;

    ASSERT(node->isElementNode());
    Element* element = static_cast<Element*>(node);
    if (element->isHTMLElement())
        return &element->getAttribute(hrefAttr);

#if ENABLE(WML)
    if (element->isWMLElement()) {
        // <anchor> elements don't have href attributes, but we still want to
        // appear as link, so linkAttribute() has to return a non-null value!
        if (element->hasTagName(WMLNames::anchorTag))
            return &emptyAtom;

        return &element->getAttribute(hrefAttr);
    }
#endif

#if ENABLE(SVG)
    if (element->isSVGElement())
        return &element->getAttribute(XLinkNames::hrefAttr);
#endif

    return 0;
}

CSSStyleSelector::SelectorChecker::SelectorChecker(Document* document, bool strictParsing)
    : m_document(document)
    , m_strictParsing(strictParsing)
    , m_collectRulesOnly(false)
    , m_pseudoStyle(NOPSEUDO)
    , m_documentIsHTML(document->isHTMLDocument())
{
}

PseudoState CSSStyleSelector::SelectorChecker::checkPseudoState(Element* element, bool checkVisited) const
{
    const AtomicString* attr = linkAttribute(element);
    if (!attr || attr->isNull())
        return PseudoNone;

    if (!checkVisited)
        return PseudoAnyLink;

    LinkHash hash = visitedLinkHash(m_document->baseURL(), *attr);
    if (!hash)
        return PseudoLink;

    Frame* frame = m_document->frame();
    if (!frame)
        return PseudoLink;

    Page* page = frame->page();
    if (!page)
        return PseudoLink;

    m_linksCheckedForVisitedState.add(hash);
    return page->group().isLinkVisited(hash) ? PseudoVisited : PseudoLink;
}

bool CSSStyleSelector::SelectorChecker::checkSelector(CSSSelector* sel, Element* element) const
{
    pseudoState = PseudoUnknown;
    PseudoId dynamicPseudo = NOPSEUDO;

    return checkSelector(sel, element, 0, dynamicPseudo, true, false) == SelectorMatches;
}

#ifdef STYLE_SHARING_STATS
static int fraction = 0;
static int total = 0;
#endif

static const unsigned cStyleSearchThreshold = 10;

Node* CSSStyleSelector::locateCousinList(Element* parent, unsigned depth)
{
    if (parent && parent->isStyledElement()) {
        StyledElement* p = static_cast<StyledElement*>(parent);
        if (!p->inlineStyleDecl() && !p->hasID()) {
            Node* r = p->previousSibling();
            unsigned subcount = 0;
            RenderStyle* st = p->renderStyle();
            while (r) {
                if (r->renderStyle() == st)
                    return r->lastChild();
                if (subcount++ == cStyleSearchThreshold)
                    return 0;
                r = r->previousSibling();
            }
            if (!r && depth < cStyleSearchThreshold)
                r = locateCousinList(parent->parentElement(), depth + 1);
            while (r) {
                if (r->renderStyle() == st)
                    return r->lastChild();
                if (subcount++ == cStyleSearchThreshold)
                    return 0;
                r = r->previousSibling();
            }
        }
    }
    return 0;
}

bool CSSStyleSelector::canShareStyleWithElement(Node* n)
{
    if (n->isStyledElement()) {
        StyledElement* s = static_cast<StyledElement*>(n);
        RenderStyle* style = s->renderStyle();
        if (style && !style->unique() &&
            (s->tagQName() == m_element->tagQName()) && !s->hasID() &&
            (s->hasClass() == m_element->hasClass()) && !s->inlineStyleDecl() &&
            (s->hasMappedAttributes() == m_styledElement->hasMappedAttributes()) &&
            (s->isLink() == m_element->isLink()) && 
            !style->affectedByAttributeSelectors() &&
            (s->hovered() == m_element->hovered()) &&
            (s->active() == m_element->active()) &&
            (s->focused() == m_element->focused()) &&
            (s != s->document()->cssTarget() && m_element != m_element->document()->cssTarget()) &&
            (s->getAttribute(typeAttr) == m_element->getAttribute(typeAttr)) &&
            (s->getAttribute(XMLNames::langAttr) == m_element->getAttribute(XMLNames::langAttr)) &&
            (s->getAttribute(langAttr) == m_element->getAttribute(langAttr)) &&
            (s->getAttribute(readonlyAttr) == m_element->getAttribute(readonlyAttr)) &&
            (s->getAttribute(cellpaddingAttr) == m_element->getAttribute(cellpaddingAttr))) {
            bool isControl = s->isFormControlElement();
            if (isControl != m_element->isFormControlElement())
                return false;
            if (isControl) {
                InputElement* thisInputElement = toInputElement(s);
                InputElement* otherInputElement = toInputElement(m_element);
                if (thisInputElement && otherInputElement) {
                    if ((thisInputElement->isAutofilled() != otherInputElement->isAutofilled()) ||
                        (thisInputElement->isChecked() != otherInputElement->isChecked()) ||
                        (thisInputElement->isIndeterminate() != otherInputElement->isIndeterminate()))
                    return false;
                } else
                    return false;

                FormControlElement* thisFormControlElement = toFormControlElement(s);
                FormControlElement* otherFormControlElement = toFormControlElement(m_element);
                if (thisFormControlElement && otherFormControlElement) {
                    if (thisFormControlElement->isEnabled() != otherFormControlElement->isEnabled())
                        return false;
                } else
                    return false;
            }

            if (style->transitions() || style->animations())
                return false;

            bool classesMatch = true;
            if (s->hasClass()) {
                const AtomicString& class1 = m_element->getAttribute(classAttr);
                const AtomicString& class2 = s->getAttribute(classAttr);
                classesMatch = (class1 == class2);
            }
            
            if (classesMatch) {
                bool mappedAttrsMatch = true;
                if (s->hasMappedAttributes())
                    mappedAttrsMatch = s->mappedAttributes()->mapsEquivalent(m_styledElement->mappedAttributes());
                if (mappedAttrsMatch) {
                    bool linksMatch = true;

                    if (s->isLink()) {
                        // We need to check to see if the visited state matches.
                        if (pseudoState == PseudoUnknown) {
                            const Color& linkColor = m_element->document()->linkColor();
                            const Color& visitedColor = m_element->document()->visitedLinkColor();
                            pseudoState = m_checker.checkPseudoState(m_element, style->pseudoState() != PseudoAnyLink || linkColor != visitedColor);
                        }
                        linksMatch = (pseudoState == style->pseudoState());
                    }
                    
                    if (linksMatch)
                        return true;
                }
            }
        }
    }
    return false;
}

RenderStyle* CSSStyleSelector::locateSharedStyle()
{
    if (m_styledElement && !m_styledElement->inlineStyleDecl() && !m_styledElement->hasID() && !m_styledElement->document()->usesSiblingRules()) {
        // Check previous siblings.
        unsigned count = 0;
        Node* n;
        for (n = m_element->previousSibling(); n && !n->isElementNode(); n = n->previousSibling()) { }