cssstyleselector.cpp

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        while (n) {
            if (canShareStyleWithElement(n))
                return n->renderStyle();
            if (count++ == cStyleSearchThreshold)
                return 0;
            for (n = n->previousSibling(); n && !n->isElementNode(); n = n->previousSibling()) { }
        }
        if (!n) 
            n = locateCousinList(m_element->parentElement());
        while (n) {
            if (canShareStyleWithElement(n))
                return n->renderStyle();
            if (count++ == cStyleSearchThreshold)
                return 0;
            for (n = n->previousSibling(); n && !n->isElementNode(); n = n->previousSibling()) { }
        }        
    }
    return 0;
}

void CSSStyleSelector::matchUARules(int& firstUARule, int& lastUARule)
{
    // First we match rules from the user agent sheet.
    CSSRuleSet* userAgentStyleSheet = m_medium->mediaTypeMatchSpecific("print")
        ? defaultPrintStyle : defaultStyle;
    matchRules(userAgentStyleSheet, firstUARule, lastUARule);

    // In quirks mode, we match rules from the quirks user agent sheet.
    if (!m_checker.m_strictParsing)
        matchRules(defaultQuirksStyle, firstUARule, lastUARule);
        
    // If we're in view source mode, then we match rules from the view source style sheet.
    if (m_checker.m_document->frame() && m_checker.m_document->frame()->inViewSourceMode()) {
        if (!defaultViewSourceStyle)
            loadViewSourceStyle();
        matchRules(defaultViewSourceStyle, firstUARule, lastUARule);
    }
}

// If resolveForRootDefault is true, style based on user agent style sheet only. This is used in media queries, where
// relative units are interpreted according to document root element style, styled only with UA stylesheet

PassRefPtr<RenderStyle> CSSStyleSelector::styleForElement(Element* e, RenderStyle* defaultParent, bool allowSharing, bool resolveForRootDefault)
{
    // Once an element has a renderer, we don't try to destroy it, since otherwise the renderer
    // will vanish if a style recalc happens during loading.
    if (allowSharing && !e->document()->haveStylesheetsLoaded() && !e->renderer()) {
        if (!s_styleNotYetAvailable) {
            s_styleNotYetAvailable = ::new RenderStyle;
            s_styleNotYetAvailable->ref();
            s_styleNotYetAvailable->setDisplay(NONE);
            s_styleNotYetAvailable->font().update(m_fontSelector);
        }
        s_styleNotYetAvailable->ref();
        e->document()->setHasNodesWithPlaceholderStyle();
        return s_styleNotYetAvailable;
    }

    initElementAndPseudoState(e);
    if (allowSharing) {
        RenderStyle* sharedStyle = locateSharedStyle();
        if (sharedStyle)
            return sharedStyle;
    }
    initForStyleResolve(e, defaultParent);

    m_style = RenderStyle::create();

    if (m_parentStyle)
        m_style->inheritFrom(m_parentStyle);
    else
        m_parentStyle = style();

    if (simpleDefaultStyleSheet && !elementCanUseSimpleDefaultStyle(e))
        loadFullDefaultStyle();

#if ENABLE(SVG)
    static bool loadedSVGUserAgentSheet;
    if (e->isSVGElement() && !loadedSVGUserAgentSheet) {
        // SVG rules.
        loadedSVGUserAgentSheet = true;
        CSSStyleSheet* svgSheet = parseUASheet(svgUserAgentStyleSheet, sizeof(svgUserAgentStyleSheet));
        defaultStyle->addRulesFromSheet(svgSheet, screenEval());
        defaultPrintStyle->addRulesFromSheet(svgSheet, printEval());
    }
#endif

#if ENABLE(WML)
    static bool loadedWMLUserAgentSheet;
    if (e->isWMLElement() && !loadedWMLUserAgentSheet) {
        // WML rules.
        loadedWMLUserAgentSheet = true;
        CSSStyleSheet* wmlSheet = parseUASheet(wmlUserAgentStyleSheet, sizeof(wmlUserAgentStyleSheet));
        defaultStyle->addRulesFromSheet(wmlSheet, screenEval());
        defaultPrintStyle->addRulesFromSheet(wmlSheet, printEval());
    }
#endif

#if ENABLE(VIDEO)
    static bool loadedMediaStyleSheet;
    if (!loadedMediaStyleSheet && (e->hasTagName(videoTag) || e->hasTagName(audioTag))) {
        loadedMediaStyleSheet = true;
        String mediaRules = String(mediaControlsUserAgentStyleSheet, sizeof(mediaControlsUserAgentStyleSheet)) + theme()->extraMediaControlsStyleSheet();
        CSSStyleSheet* mediaControlsSheet = parseUASheet(mediaRules);
        defaultStyle->addRulesFromSheet(mediaControlsSheet, screenEval());
        defaultPrintStyle->addRulesFromSheet(mediaControlsSheet, printEval());
    }
#endif

    int firstUARule = -1, lastUARule = -1;
    int firstUserRule = -1, lastUserRule = -1;
    int firstAuthorRule = -1, lastAuthorRule = -1;
    matchUARules(firstUARule, lastUARule);

    if (!resolveForRootDefault) {
        // 4. Now we check user sheet rules.
        if (m_matchAuthorAndUserStyles)
            matchRules(m_userStyle, firstUserRule, lastUserRule);

        // 5. Now check author rules, beginning first with presentational attributes
        // mapped from HTML.
        if (m_styledElement) {
            // Ask if the HTML element has mapped attributes.
            if (m_styledElement->hasMappedAttributes()) {
                // Walk our attribute list and add in each decl.
                const NamedMappedAttrMap* map = m_styledElement->mappedAttributes();
                for (unsigned i = 0; i < map->length(); i++) {
                    Attribute* attr = map->attributeItem(i);
                    if (attr->isMappedAttribute()) {
                        MappedAttribute* mappedAttr = static_cast<MappedAttribute*>(attr);
                        if (mappedAttr->decl()) {
                            lastAuthorRule = m_matchedDecls.size();
                            if (firstAuthorRule == -1)
                                firstAuthorRule = lastAuthorRule;
                            addMatchedDeclaration(mappedAttr->decl());
                        }
                    }
                }
            }

            // Now we check additional mapped declarations.
            // Tables and table cells share an additional mapped rule that must be applied
            // after all attributes, since their mapped style depends on the values of multiple attributes.
            if (m_styledElement->canHaveAdditionalAttributeStyleDecls()) {
                m_additionalAttributeStyleDecls.clear();
                m_styledElement->additionalAttributeStyleDecls(m_additionalAttributeStyleDecls);
                if (!m_additionalAttributeStyleDecls.isEmpty()) {
                    unsigned additionalDeclsSize = m_additionalAttributeStyleDecls.size();
                    if (firstAuthorRule == -1)
                        firstAuthorRule = m_matchedDecls.size();
                    lastAuthorRule = m_matchedDecls.size() + additionalDeclsSize - 1;
                    for (unsigned i = 0; i < additionalDeclsSize; i++)
                        addMatchedDeclaration(m_additionalAttributeStyleDecls[i]);
                }
            }
        }
    
        // 6. Check the rules in author sheets next.
        if (m_matchAuthorAndUserStyles)
            matchRules(m_authorStyle, firstAuthorRule, lastAuthorRule);

        // 7. Now check our inline style attribute.
        if (m_matchAuthorAndUserStyles && m_styledElement) {
            CSSMutableStyleDeclaration* inlineDecl = m_styledElement->inlineStyleDecl();
            if (inlineDecl) {
                lastAuthorRule = m_matchedDecls.size();
                if (firstAuthorRule == -1)
                    firstAuthorRule = lastAuthorRule;
                addMatchedDeclaration(inlineDecl);
            }
        }
    }

    // Now we have all of the matched rules in the appropriate order.  Walk the rules and apply
    // high-priority properties first, i.e., those properties that other properties depend on.
    // The order is (1) high-priority not important, (2) high-priority important, (3) normal not important
    // and (4) normal important.
    m_lineHeightValue = 0;
    applyDeclarations(true, false, 0, m_matchedDecls.size() - 1);
    if (!resolveForRootDefault) {
        applyDeclarations(true, true, firstAuthorRule, lastAuthorRule);
        applyDeclarations(true, true, firstUserRule, lastUserRule);
    }
    applyDeclarations(true, true, firstUARule, lastUARule);
    
    // If our font got dirtied, go ahead and update it now.
    if (m_fontDirty)
        updateFont();

    // Line-height is set when we are sure we decided on the font-size
    if (m_lineHeightValue)
        applyProperty(CSSPropertyLineHeight, m_lineHeightValue);

    // Now do the normal priority UA properties.
    applyDeclarations(false, false, firstUARule, lastUARule);
    
    // Cache our border and background so that we can examine them later.
    cacheBorderAndBackground();
    
    // Now do the author and user normal priority properties and all the !important properties.
    if (!resolveForRootDefault) {
        applyDeclarations(false, false, lastUARule + 1, m_matchedDecls.size() - 1);
        applyDeclarations(false, true, firstAuthorRule, lastAuthorRule);
        applyDeclarations(false, true, firstUserRule, lastUserRule);
    }
    applyDeclarations(false, true, firstUARule, lastUARule);
    
    // If our font got dirtied by one of the non-essential font props, 
    // go ahead and update it a second time.
    if (m_fontDirty)
        updateFont();
    
    // Clean up our style object's display and text decorations (among other fixups).
    adjustRenderStyle(style(), e);

    // If we are a link, cache the determined pseudo-state.
    if (e->isLink())
        m_style->setPseudoState(pseudoState);

    // If we have first-letter pseudo style, do not share this style
    if (m_style->hasPseudoStyle(FIRST_LETTER))
        m_style->setUnique();

    // Now return the style.
    return m_style.release();
}

void CSSStyleSelector::keyframeStylesForAnimation(Element* e, const RenderStyle* elementStyle, KeyframeList& list)
{
    list.clear();
    
    // Get the keyframesRule for this name
    if (!e || list.animationName().isEmpty())
        return;
            
    if (!m_keyframesRuleMap.contains(list.animationName().impl()))
        return;
        
    const WebKitCSSKeyframesRule* rule = m_keyframesRuleMap.find(list.animationName().impl()).get()->second.get();
    
    // Construct and populate the style for each keyframe
    for (unsigned i = 0; i < rule->length(); ++i) {
        // Apply the declaration to the style. This is a simplified version of the logic in styleForElement
        initElementAndPseudoState(e);
        initForStyleResolve(e);
        
        const WebKitCSSKeyframeRule* kf = rule->item(i);
        addMatchedDeclaration(kf->style());

        ASSERT(!m_style);

        // Create the style
        m_style = RenderStyle::clone(elementStyle);
        
        m_lineHeightValue = 0;
        
        // We don't need to bother with !important. Since there is only ever one
        // decl, there's nothing to override. So just add the first properties.
        applyDeclarations(true, false, 0, m_matchedDecls.size() - 1);
        
        // If our font got dirtied, go ahead and update it now.
        if (m_fontDirty)
            updateFont();

        // Line-height is set when we are sure we decided on the font-size
        if (m_lineHeightValue)
            applyProperty(CSSPropertyLineHeight, m_lineHeightValue);
        
        // Now do rest of the properties.
        applyDeclarations(false, false, 0, m_matchedDecls.size() - 1);
        
        // If our font got dirtied by one of the non-essential font props, 
        // go ahead and update it a second time.
        if (m_fontDirty)
            updateFont();

        // Add all the animating properties to the list
        CSSMutableStyleDeclaration::const_iterator end = kf->style()->end();
        for (CSSMutableStyleDeclaration::const_iterator it = kf->style()->begin(); it != end; ++it)
            list.addProperty((*it).id());
        
        // Add this keyframe style to all the indicated key times
        Vector<float> keys;
        kf->getKeys(keys);
        for (size_t keyIndex = 0; keyIndex < keys.size(); ++keyIndex) {
            float key = keys[keyIndex];
            list.insert(key, m_style);
        }
        m_style = 0;
    }
    
    // Make sure there is a 0% and a 100% keyframe
    float first = -1;
    float last = -1;
    if (list.size() >= 2) {
        first = list.beginKeyframes()->key();
        last = (list.endKeyframes()-1)->key();
    }
    if (first != 0 || last != 1)
        list.clear();
}

PassRefPtr<RenderStyle> CSSStyleSelector::pseudoStyleForElement(PseudoId pseudo, Element* e, RenderStyle* parentStyle)
{
    if (!e)
        return 0;

    initElementAndPseudoState(e);
    initForStyleResolve(e, parentStyle, pseudo);
    m_style = parentStyle;
    
    // Since we don't use pseudo-elements in any of our quirk/print user agent rules, don't waste time walking
    // those rules.
    
    // Check UA, user and author rules.
    int firstUARule = -1, lastUARule = -1, firstUserRule = -1, lastUserRule = -1, firstAuthorRule = -1, lastAuthorRule = -1;
    matchUARules(firstUARule, lastUARule);

    if (m_matchAuthorAndUserStyles) {
        matchRules(m_userStyle, firstUserRule, lastUserRule);
        matchRules(m_authorStyle, firstAuthorRule, lastAuthorRule);
    }

    if (m_matchedDecls.isEmpty())
        return 0;
    
    m_style = RenderStyle::create();
    if (parentStyle)
        m_style->inheritFrom(parentStyle);

    m_style->noninherited_flags._styleType = pseudo;
    
    m_lineHeightValue = 0;
    // High-priority properties.
    applyDeclarations(true, false, 0, m_matchedDecls.size() - 1);
    applyDeclarations(true, true, firstAuthorRule, lastAuthorRule);
    applyDeclarations(true, true, firstUserRule, lastUserRule);