cssstyleselector.cpp

linux下开源浏览器WebKit的源码,市面上的很多商用浏览器都是移植自WebKit

class CSSRuleSet {
public:
    CSSRuleSet();
    ~CSSRuleSet();
    
    typedef HashMap<AtomicStringImpl*, CSSRuleDataList*> AtomRuleMap;
    
    void addRulesFromSheet(CSSStyleSheet*, const MediaQueryEvaluator&, CSSStyleSelector* = 0);
    
    void addRule(CSSStyleRule* rule, CSSSelector* sel);
    void addToRuleSet(AtomicStringImpl* key, AtomRuleMap& map,
                      CSSStyleRule* rule, CSSSelector* sel);
    
    CSSRuleDataList* getIDRules(AtomicStringImpl* key) { return m_idRules.get(key); }
    CSSRuleDataList* getClassRules(AtomicStringImpl* key) { return m_classRules.get(key); }
    CSSRuleDataList* getTagRules(AtomicStringImpl* key) { return m_tagRules.get(key); }
    CSSRuleDataList* getUniversalRules() { return m_universalRules; }
    
public:
    AtomRuleMap m_idRules;
    AtomRuleMap m_classRules;
    AtomRuleMap m_tagRules;
    CSSRuleDataList* m_universalRules;
    unsigned m_ruleCount;
};

static CSSRuleSet* defaultStyle;
static CSSRuleSet* defaultQuirksStyle;
static CSSRuleSet* defaultPrintStyle;
static CSSRuleSet* defaultViewSourceStyle;
static CSSStyleSheet* simpleDefaultStyleSheet;

RenderStyle* CSSStyleSelector::s_styleNotYetAvailable;

static PseudoState pseudoState;

static void loadFullDefaultStyle();
static void loadSimpleDefaultStyle();
// FIXME: It would be nice to use some mechanism that guarantees this is in sync with the real UA stylesheet.
static const char* simpleUserAgentStyleSheet = "html,body,div{display:block}body{margin:8px}div:focus,span:focus{outline:auto 5px -webkit-focus-ring-color}";

static bool elementCanUseSimpleDefaultStyle(Element* e)
{
    return e->hasTagName(htmlTag) || e->hasTagName(bodyTag) || e->hasTagName(divTag) || e->hasTagName(spanTag) || e->hasTagName(brTag);
}

static const MediaQueryEvaluator& screenEval()
{
    DEFINE_STATIC_LOCAL(const MediaQueryEvaluator, staticScreenEval, ("screen"));
    return staticScreenEval;
}

static const MediaQueryEvaluator& printEval()
{
    DEFINE_STATIC_LOCAL(const MediaQueryEvaluator, staticPrintEval, ("print"));
    return staticPrintEval;
}

CSSStyleSelector::CSSStyleSelector(Document* doc, const String& userStyleSheet, StyleSheetList* styleSheets, CSSStyleSheet* mappedElementSheet, bool strictParsing, bool matchAuthorAndUserStyles)
    : m_backgroundData(BackgroundFillLayer)
    , m_checker(doc, strictParsing)
    , m_fontSelector(CSSFontSelector::create(doc))
{
    init();

    m_matchAuthorAndUserStyles = matchAuthorAndUserStyles;
    
    Element* root = doc->documentElement();

    if (!defaultStyle) {
        if (!root || elementCanUseSimpleDefaultStyle(root))
            loadSimpleDefaultStyle();
        else
            loadFullDefaultStyle();
    }

    m_userStyle = 0;

    // construct document root element default style. this is needed
    // to evaluate media queries that contain relative constraints, like "screen and (max-width: 10em)"
    // This is here instead of constructor, because when constructor is run,
    // document doesn't have documentElement
    // NOTE: this assumes that element that gets passed to styleForElement -call
    // is always from the document that owns the style selector
    FrameView* view = doc->view();
    if (view)
        m_medium = new MediaQueryEvaluator(view->mediaType());
    else
        m_medium = new MediaQueryEvaluator("all");

    if (root)
        m_rootDefaultStyle = styleForElement(root, 0, false, true); // dont ref, because the RenderStyle is allocated from global heap

    if (m_rootDefaultStyle && view) {
        delete m_medium;
        m_medium = new MediaQueryEvaluator(view->mediaType(), view->frame(), m_rootDefaultStyle.get());
    }

    // FIXME: This sucks! The user sheet is reparsed every time!
    if (!userStyleSheet.isEmpty()) {
        m_userSheet = CSSStyleSheet::create(doc);
        m_userSheet->parseString(userStyleSheet, strictParsing);

        m_userStyle = new CSSRuleSet();
        m_userStyle->addRulesFromSheet(m_userSheet.get(), *m_medium, this);
    }

    // add stylesheets from document
    m_authorStyle = new CSSRuleSet();
    
    // Add rules from elments like SVG's <font-face>
    if (mappedElementSheet)
        m_authorStyle->addRulesFromSheet(mappedElementSheet, *m_medium, this);

    unsigned length = styleSheets->length();
    for (unsigned i = 0; i < length; i++) {
        StyleSheet* sheet = styleSheets->item(i);
        if (sheet->isCSSStyleSheet() && !sheet->disabled())
            m_authorStyle->addRulesFromSheet(static_cast<CSSStyleSheet*>(sheet), *m_medium, this);
    }
}

// This is a simplified style setting function for keyframe styles
void CSSStyleSelector::addKeyframeStyle(PassRefPtr<WebKitCSSKeyframesRule> rule)
{
    AtomicString s(rule->name());
    m_keyframesRuleMap.add(s.impl(), rule);
}

void CSSStyleSelector::init()
{
    m_element = 0;
    m_matchedDecls.clear();
    m_ruleList = 0;
    m_rootDefaultStyle = 0;
    m_medium = 0;
}

CSSStyleSelector::~CSSStyleSelector()
{
    m_fontSelector->clearDocument();
    delete m_medium;
    delete m_authorStyle;
    delete m_userStyle;
    deleteAllValues(m_viewportDependentMediaQueryResults);
    m_keyframesRuleMap.clear();
}

static CSSStyleSheet* parseUASheet(const String& str)
{
    CSSStyleSheet* sheet = CSSStyleSheet::create().releaseRef(); // leak the sheet on purpose
    sheet->parseString(str);
    return sheet;
}

static CSSStyleSheet* parseUASheet(const char* characters, unsigned size)
{
    return parseUASheet(String(characters, size));
}

static void loadFullDefaultStyle()
{
    if (simpleDefaultStyleSheet) {
        ASSERT(defaultStyle);
        delete defaultStyle;
        delete simpleDefaultStyleSheet;
        defaultStyle = new CSSRuleSet;
        simpleDefaultStyleSheet = 0;
    } else {
        ASSERT(!defaultStyle);
        defaultStyle = new CSSRuleSet;
        defaultPrintStyle = new CSSRuleSet;
        defaultQuirksStyle = new CSSRuleSet;
    }

    // Strict-mode rules.
    String defaultRules = String(html4UserAgentStyleSheet, sizeof(html4UserAgentStyleSheet)) + theme()->extraDefaultStyleSheet();
    CSSStyleSheet* defaultSheet = parseUASheet(defaultRules);
    defaultStyle->addRulesFromSheet(defaultSheet, screenEval());
    defaultPrintStyle->addRulesFromSheet(defaultSheet, printEval());

    // Quirks-mode rules.
    String quirksRules = String(quirksUserAgentStyleSheet, sizeof(quirksUserAgentStyleSheet)) + theme()->extraQuirksStyleSheet();
    CSSStyleSheet* quirksSheet = parseUASheet(quirksRules);
    defaultQuirksStyle->addRulesFromSheet(quirksSheet, screenEval());
}

static void loadSimpleDefaultStyle()
{
    ASSERT(!defaultStyle);
    ASSERT(!simpleDefaultStyleSheet);
    
    defaultStyle = new CSSRuleSet;
    defaultPrintStyle = new CSSRuleSet;
    defaultQuirksStyle = new CSSRuleSet;

    simpleDefaultStyleSheet = parseUASheet(simpleUserAgentStyleSheet, strlen(simpleUserAgentStyleSheet));
    defaultStyle->addRulesFromSheet(simpleDefaultStyleSheet, screenEval());
    
    // No need to initialize quirks sheet yet as there are no quirk rules for elements allowed in simple default style.
}
    
static void loadViewSourceStyle()
{
    ASSERT(!defaultViewSourceStyle);
    defaultViewSourceStyle = new CSSRuleSet;
    defaultViewSourceStyle->addRulesFromSheet(parseUASheet(sourceUserAgentStyleSheet, sizeof(sourceUserAgentStyleSheet)), screenEval());
}

void CSSStyleSelector::addMatchedDeclaration(CSSMutableStyleDeclaration* decl)
{
    if (!decl->hasVariableDependentValue()) {
        m_matchedDecls.append(decl);
        return;
    }

    // See if we have already resolved the variables in this declaration.
    CSSMutableStyleDeclaration* resolvedDecl = m_resolvedVariablesDeclarations.get(decl).get();
    if (resolvedDecl) {
        m_matchedDecls.append(resolvedDecl);
        return;
    }

    // If this declaration has any variables in it, then we need to make a cloned
    // declaration with as many variables resolved as possible for this style selector's media.
    RefPtr<CSSMutableStyleDeclaration> newDecl = CSSMutableStyleDeclaration::create(decl->parentRule());
    m_matchedDecls.append(newDecl.get());
    m_resolvedVariablesDeclarations.set(decl, newDecl);

    HashSet<String> usedBlockVariables;
    resolveVariablesForDeclaration(decl, newDecl.get(), usedBlockVariables);
}

void CSSStyleSelector::resolveVariablesForDeclaration(CSSMutableStyleDeclaration* decl, CSSMutableStyleDeclaration* newDecl, HashSet<String>& usedBlockVariables)
{
    // Now iterate over the properties in the original declaration.  As we resolve variables we'll end up
    // mutating the new declaration (possibly expanding shorthands).  The new declaration has no m_node
    // though, so it can't mistakenly call setChanged on anything.
    CSSMutableStyleDeclaration::const_iterator end = decl->end();
    for (CSSMutableStyleDeclaration::const_iterator it = decl->begin(); it != end; ++it) {
        const CSSProperty& current = *it;
        if (!current.value()->isVariableDependentValue()) {
            // We can just add the parsed property directly.
            newDecl->addParsedProperty(current);
            continue;
        }
        CSSValueList* valueList = static_cast<CSSVariableDependentValue*>(current.value())->valueList();
        if (!valueList)
            continue;
        CSSParserValueList resolvedValueList;
        unsigned s = valueList->length();
        bool fullyResolved = true;
        for (unsigned i = 0; i < s; ++i) {
            CSSValue* val = valueList->item(i);
            CSSPrimitiveValue* primitiveValue = val->isPrimitiveValue() ? static_cast<CSSPrimitiveValue*>(val) : 0;
            if (primitiveValue && primitiveValue->isVariable()) {
                CSSVariablesRule* rule = m_variablesMap.get(primitiveValue->getStringValue());
                if (!rule || !rule->variables()) {
                    fullyResolved = false;
                    break;
                }
                
                if (current.id() == CSSPropertyWebkitVariableDeclarationBlock && s == 1) {
                    fullyResolved = false;
                    if (!usedBlockVariables.contains(primitiveValue->getStringValue())) {
                        CSSMutableStyleDeclaration* declBlock = rule->variables()->getParsedVariableDeclarationBlock(primitiveValue->getStringValue());
                        if (declBlock) {
                            usedBlockVariables.add(primitiveValue->getStringValue());
                            resolveVariablesForDeclaration(declBlock, newDecl, usedBlockVariables);
                        }
                    }
                }

                CSSValueList* resolvedVariable = rule->variables()->getParsedVariable(primitiveValue->getStringValue());
                if (!resolvedVariable) {
                    fullyResolved = false;
                    break;
                }
                unsigned valueSize = resolvedVariable->length();
                for (unsigned j = 0; j < valueSize; ++j)
                    resolvedValueList.addValue(resolvedVariable->item(j)->parserValue());
            } else
                resolvedValueList.addValue(val->parserValue());
        }
        
        if (!fullyResolved)
            continue;

        // We now have a fully resolved new value list.  We want the parser to use this value list
        // and parse our new declaration.
        CSSParser(m_checker.m_strictParsing).parsePropertyWithResolvedVariables(current.id(), current.isImportant(), newDecl, &resolvedValueList);
    }
}

void CSSStyleSelector::matchRules(CSSRuleSet* rules, int& firstRuleIndex, int& lastRuleIndex)
{
    m_matchedRules.clear();

    if (!rules || !m_element)
        return;
    
    // We need to collect the rules for id, class, tag, and everything else into a buffer and
    // then sort the buffer.
    if (m_element->hasID())
        matchRulesForList(rules->getIDRules(m_element->getIDAttribute().impl()), firstRuleIndex, lastRuleIndex);
    if (m_element->hasClass()) {
        ASSERT(m_styledElement);
        const ClassNames& classNames = m_styledElement->classNames();
        size_t size = classNames.size();
        for (size_t i = 0; i < size; ++i)
            matchRulesForList(rules->getClassRules(classNames[i].impl()), firstRuleIndex, lastRuleIndex);
    }
    matchRulesForList(rules->getTagRules(m_element->localName().impl()), firstRuleIndex, lastRuleIndex);
    matchRulesForList(rules->getUniversalRules(), firstRuleIndex, lastRuleIndex);
    
    // If we didn't match any rules, we're done.
    if (m_matchedRules.isEmpty())
        return;
    
    // Sort the set of matched rules.
    sortMatchedRules(0, m_matchedRules.size());
    
    // Now transfer the set of matched rules over to our list of decls.
    if (!m_checker.m_collectRulesOnly) {
        for (unsigned i = 0; i < m_matchedRules.size(); i++)
            addMatchedDeclaration(m_matchedRules[i]->rule()->declaration());
    } else {
        for (unsigned i = 0; i < m_matchedRules.size(); i++) {
            if (!m_ruleList)
                m_ruleList = CSSRuleList::create();
            m_ruleList->append(m_matchedRules[i]->rule());
        }
    }
}

void CSSStyleSelector::matchRulesForList(CSSRuleDataList* rules, int& firstRuleIndex, int& lastRuleIndex)
{