document.cpp

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        m_renderArena = new RenderArena();
    
    // Create the rendering tree
    setRenderer(new (m_renderArena) RenderView(this, view()));
#if USE(ACCELERATED_COMPOSITING)
    renderView()->didMoveOnscreen();
#endif

    if (!m_styleSelector) {
        bool matchAuthorAndUserStyles = true;
        if (Settings* docSettings = settings())
            matchAuthorAndUserStyles = docSettings->authorAndUserStylesEnabled();
        m_styleSelector = new CSSStyleSelector(this, userStyleSheet(), m_styleSheets.get(), m_mappedElementSheet.get(), !inCompatMode(), matchAuthorAndUserStyles);
    }

    recalcStyle(Force);

    RenderObject* render = renderer();
    setRenderer(0);

    ContainerNode::attach();

    setRenderer(render);
}

void Document::detach()
{
    ASSERT(attached());
    ASSERT(!m_inPageCache);

    clearAXObjectCache();
    stopActiveDOMObjects();
    
    RenderObject* render = renderer();

    // Send out documentWillBecomeInactive() notifications to registered elements,
    // in order to stop media elements
    documentWillBecomeInactive();
    
    // indicate destruction mode,  i.e. attached() but renderer == 0
    setRenderer(0);
    
    // Empty out these lists as a performance optimization, since detaching
    // all the individual render objects will cause all the RenderImage
    // objects to remove themselves from the lists.
    m_imageLoadEventDispatchSoonList.clear();
    m_imageLoadEventDispatchingList.clear();
    
    m_hoverNode = 0;
    m_focusedNode = 0;
    m_activeNode = 0;

    ContainerNode::detach();

    if (render)
        render->destroy();
    
    // This is required, as our Frame might delete itself as soon as it detaches
    // us.  However, this violates Node::detach() symantics, as it's never
    // possible to re-attach.  Eventually Document::detach() should be renamed
    // or this call made explicit in each of the callers of Document::detach().
    clearFramePointer();
    
    if (m_renderArena) {
        delete m_renderArena;
        m_renderArena = 0;
    }
}

void Document::clearFramePointer()
{
    m_frame = 0;
}

void Document::removeAllEventListenersFromAllNodes()
{
    size_t size = m_windowEventListeners.size();
    for (size_t i = 0; i < size; ++i)
        m_windowEventListeners[i]->setRemoved(true);
    m_windowEventListeners.clear();
    removeAllDisconnectedNodeEventListeners();
    for (Node* node = this; node; node = node->traverseNextNode())
        node->removeAllEventListeners();
}

void Document::registerDisconnectedNodeWithEventListeners(Node* node)
{
    m_disconnectedNodesWithEventListeners.add(node);
}

void Document::unregisterDisconnectedNodeWithEventListeners(Node* node)
{
    m_disconnectedNodesWithEventListeners.remove(node);
}

void Document::removeAllDisconnectedNodeEventListeners()
{
    HashSet<Node*>::iterator end = m_disconnectedNodesWithEventListeners.end();
    for (HashSet<Node*>::iterator i = m_disconnectedNodesWithEventListeners.begin(); i != end; ++i)
        (*i)->removeAllEventListeners();
    m_disconnectedNodesWithEventListeners.clear();
}

RenderView* Document::renderView() const
{
    return toRenderView(renderer());
}

void Document::clearAXObjectCache()
{
    // clear cache in top document
    if (m_axObjectCache) {
        delete m_axObjectCache;
        m_axObjectCache = 0;
        return;
    }
    
    // ask the top-level document to clear its cache
    Document* doc = topDocument();
    if (doc != this)
        doc->clearAXObjectCache();
}

AXObjectCache* Document::axObjectCache() const
{
    // The only document that actually has a AXObjectCache is the top-level
    // document.  This is because we need to be able to get from any WebCoreAXObject
    // to any other WebCoreAXObject on the same page.  Using a single cache allows
    // lookups across nested webareas (i.e. multiple documents).
    
    if (m_axObjectCache) {
        // return already known top-level cache
        if (!ownerElement())
            return m_axObjectCache;
        
        // In some pages with frames, the cache is created before the sub-webarea is
        // inserted into the tree.  Here, we catch that case and just toss the old
        // cache and start over.
        // NOTE: This recovery may no longer be needed. I have been unable to trigger
        // it again. See rdar://5794454
        // FIXME: Can this be fixed when inserting the subframe instead of now?
        // FIXME: If this function was called to get the cache in order to remove
        // an AXObject, we are now deleting the cache as a whole and returning a
        // new empty cache that does not contain the AXObject! That should actually
        // be OK. I am concerned about other cases like this where accessing the
        // cache blows away the AXObject being operated on.
        delete m_axObjectCache;
        m_axObjectCache = 0;
    }

    // ask the top-level document for its cache
    Document* doc = topDocument();
    if (doc != this)
        return doc->axObjectCache();
    
    // this is the top-level document, so install a new cache
    m_axObjectCache = new AXObjectCache;
    return m_axObjectCache;
}

void Document::setVisuallyOrdered()
{
    visuallyOrdered = true;
    if (renderer())
        renderer()->style()->setVisuallyOrdered(true);
}

Tokenizer* Document::createTokenizer()
{
    // FIXME: this should probably pass the frame instead
    return new XMLTokenizer(this, view());
}

void Document::open(Document* ownerDocument)
{
    if (ownerDocument) {
        setURL(ownerDocument->url());
        m_cookieURL = ownerDocument->cookieURL();
        ScriptExecutionContext::setSecurityOrigin(ownerDocument->securityOrigin());
    }

    if (m_frame) {
        if (m_frame->loader()->isLoadingMainResource() || (tokenizer() && tokenizer()->executingScript()))
            return;
    
        if (m_frame->loader()->state() == FrameStateProvisional)
            m_frame->loader()->stopAllLoaders();
    }
    
    implicitOpen();

    if (m_frame)
        m_frame->loader()->didExplicitOpen();
}

void Document::cancelParsing()
{
    if (m_tokenizer) {
        // We have to clear the tokenizer to avoid possibly triggering
        // the onload handler when closing as a side effect of a cancel-style
        // change, such as opening a new document or closing the window while
        // still parsing
        delete m_tokenizer;
        m_tokenizer = 0;
        close();
    }
}

void Document::implicitOpen()
{
    cancelParsing();

    clear();
    m_tokenizer = createTokenizer();
    setParsing(true);
}

HTMLElement* Document::body() const
{
    Node* de = documentElement();
    if (!de)
        return 0;
    
    // try to prefer a FRAMESET element over BODY
    Node* body = 0;
    for (Node* i = de->firstChild(); i; i = i->nextSibling()) {
        if (i->hasTagName(framesetTag))
            return static_cast<HTMLElement*>(i);
        
        if (i->hasTagName(bodyTag) && !body)
            body = i;
    }
    return static_cast<HTMLElement*>(body);
}

void Document::setBody(PassRefPtr<HTMLElement> newBody, ExceptionCode& ec)
{
    if (!newBody || !documentElement()) { 
        ec = HIERARCHY_REQUEST_ERR;
        return;
    }

    HTMLElement* b = body();
    if (!b)
        documentElement()->appendChild(newBody, ec);
    else
        documentElement()->replaceChild(newBody, b, ec);
}

HTMLHeadElement* Document::head()
{
    Node* de = documentElement();
    if (!de)
        return 0;

    for (Node* e = de->firstChild(); e; e = e->nextSibling())
        if (e->hasTagName(headTag))
            return static_cast<HTMLHeadElement*>(e);

    return 0;
}

void Document::close()
{
    Frame* frame = this->frame();
    if (frame) {
        // This code calls implicitClose() if all loading has completed.
        FrameLoader* frameLoader = frame->loader();
        frameLoader->endIfNotLoadingMainResource();
        frameLoader->checkCompleted();
    } else {
        // Because we have no frame, we don't know if all loading has completed,
        // so we just call implicitClose() immediately. FIXME: This might fire
        // the load event prematurely <http://bugs.webkit.org/show_bug.cgi?id=14568>.
        implicitClose();
    }
}

void Document::implicitClose()
{
    // If we're in the middle of recalcStyle, we need to defer the close until the style information is accurate and all elements are re-attached.
    if (m_inStyleRecalc) {
        m_closeAfterStyleRecalc = true;
        return;
    }

    bool wasLocationChangePending = frame() && frame()->loader()->isScheduledLocationChangePending();
    bool doload = !parsing() && m_tokenizer && !m_processingLoadEvent && !wasLocationChangePending;
    
    if (!doload)
        return;

    m_processingLoadEvent = true;

    m_wellFormed = m_tokenizer && m_tokenizer->wellFormed();

    // We have to clear the tokenizer, in case someone document.write()s from the
    // onLoad event handler, as in Radar 3206524.
    delete m_tokenizer;
    m_tokenizer = 0;

    // Parser should have picked up all preloads by now
    m_docLoader->clearPreloads();

    // Create a body element if we don't already have one. See Radar 3758785.
    if (!this->body() && isHTMLDocument()) {
        if (Node* documentElement = this->documentElement()) {
            ExceptionCode ec = 0;
            documentElement->appendChild(new HTMLBodyElement(bodyTag, this), ec);
            ASSERT(!ec);
        }
    }

    // FIXME: We kick off the icon loader when the Document is done parsing.
    // There are earlier opportunities we could start it:
    //  -When the <head> finishes parsing
    //  -When any new HTMLLinkElement is inserted into the document
    // But those add a dynamic component to the favicon that has UI 
    // ramifications, and we need to decide what is the Right Thing To Do(tm)
    Frame* f = frame();
    if (f)
        f->loader()->startIconLoader();

    // Resume the animations (or start them)
    if (f)
        f->animation()->resumeAnimations(this);

    dispatchImageLoadEventsNow();
    this->dispatchWindowEvent(eventNames().loadEvent, false, false);
    if (f)
        f->loader()->handledOnloadEvents();
#ifdef INSTRUMENT_LAYOUT_SCHEDULING
    if (!ownerElement())
        printf("onload fired at %d\n", elapsedTime());
#endif

    m_processingLoadEvent = false;

    // An event handler may have removed the frame
    if (!frame())
        return;

    // Make sure both the initial layout and reflow happen after the onload
    // fires. This will improve onload scores, and other browsers do it.
    // If they wanna cheat, we can too. -dwh

    if (frame()->loader()->isScheduledLocationChangePending() && elapsedTime() < cLayoutScheduleThreshold) {
        // Just bail out. Before or during the onload we were shifted to another page.
        // The old i-Bench suite does this. When this happens don't bother painting or laying out.        
        view()->unscheduleRelayout();
        return;
    }

    frame()->loader()->checkCallImplicitClose();

    // Now do our painting/layout, but only if we aren't in a subframe or if we're in a subframe
    // that has been sized already.  Otherwise, our view size would be incorrect, so doing any 
    // layout/painting now would be pointless.
    if (!ownerElement() || (ownerElement()->renderer() && !ownerElement()->renderer()->needsLayout())) {
        updateRendering();
        
        // Always do a layout after loading if needed.
        if (view() && renderer() && (!renderer()->firstChild() || renderer()->needsLayout()))
            view()->layout();
            
        // Paint immediately after the document is ready.  We do this to ensure that any timers set by the
        // onload don't have a chance to fire before we would have painted.  To avoid over-flushing we only
        // worry about this for the top-level document.  For platforms that use native widgets for ScrollViews, this
        // call does nothing (Mac, wx).
        // FIXME: This causes a timing issue with the dispatchDidFinishLoad delegate callback on Mac, so think
        // before enabling it, even if Mac becomes viewless later.
        // See <rdar://problem/5092361>
        if (view() && !ownerElement())
            view()->hostWindow()->paint();
    }

#if PLATFORM(MAC)
    if (f && renderer() && this == topDocument() && AXObjectCache::accessibilityEnabled())
        axObjectCache()->postNotificationToElement(renderer(), "AXLoadComplete");
#endif

#if ENABLE(SVG)
    // FIXME: Officially, time 0 is when the outermost <svg> receives its
    // SVGLoad event, but we don't implement those yet.  This is close enough
    // for now.  In some cases we should have fired earlier.
    if (svgExtensions())
        accessSVGExtensions()->startAnimations();
#endif
}

void Document::setParsing(bool b)
{
    m_bParsing = b;
    if (!m_bParsing && view())
        view()->scheduleRelayout();

#ifdef INSTRUMENT_LAYOUT_SCHEDULING
    if (!ownerElement() && !m_bParsing)
        printf("Parsing finished at %d\n", elapsedTime());
#endif
}

bool Document::shouldScheduleLayout()
{
    // This function will only be called when FrameView thinks a layout is needed.
    // This enforces a couple extra rules.
    //
    //    (a) Only schedule a layout once the stylesheets are loaded.
    //    (b) Only schedule layout once we have a body element.

    return haveStylesheetsLoaded()
        && body() || (documentElement() && !documentElement()->hasTagName(htmlTag));
}

int Document::minimumLayoutDelay()
{
    if (m_overMinimumLayoutThreshold)
        return 0;