Source/WebCore/dom/Document.cpp

/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 *           (C) 2001 Dirk Mueller (mueller@kde.org)
 *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
 * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
 * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
 * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
 * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
 * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include "config.h"
#include "Document.h"

#include "AXObjectCache.h"
#include "AnimationController.h"
#include "Attr.h"
#include "Attribute.h"
#include "CDATASection.h"
#include "CSSParser.h"
#include "CSSStyleDeclaration.h"
#include "CSSStyleSheet.h"
#include "CSSValueKeywords.h"
#include "CachedCSSStyleSheet.h"
#include "CachedResourceLoader.h"
#include "Chrome.h"
#include "ChromeClient.h"
#include "Comment.h"
#include "ContentSecurityPolicy.h"
#include "ContextFeatures.h"
#include "CookieJar.h"
#include "CustomElementConstructor.h"
#include "CustomElementRegistry.h"
#include "DOMImplementation.h"
#include "DOMNamedFlowCollection.h"
#include "DOMSelection.h"
#include "DOMWindow.h"
#include "DateComponents.h"
#include "Dictionary.h"
#include "DocumentEventQueue.h"
#include "DocumentFragment.h"
#include "DocumentLoader.h"
#include "DocumentMarkerController.h"
#include "DocumentSharedObjectPool.h"
#include "DocumentStyleSheetCollection.h"
#include "DocumentType.h"
#include "Editor.h"
#include "Element.h"
#include "ElementShadow.h"
#include "EntityReference.h"
#include "Event.h"
#include "EventFactory.h"
#include "EventHandler.h"
#include "EventListener.h"
#include "EventNames.h"
#include "ExceptionCode.h"
#include "ExceptionCodePlaceholder.h"
#include "FlowThreadController.h"
#include "FocusController.h"
#include "FontLoader.h"
#include "FormController.h"
#include "Frame.h"
#include "FrameLoader.h"
#include "FrameLoaderClient.h"
#include "FrameSelection.h"
#include "FrameTree.h"
#include "FrameView.h"
#include "GeolocationController.h"
#include "HashChangeEvent.h"
#include "HistogramSupport.h"
#include "History.h"
#include "HTMLAllCollection.h"
#include "HTMLAnchorElement.h"
#include "HTMLBodyElement.h"
#include "HTMLCanvasElement.h"
#include "HTMLCollection.h"
#include "HTMLDocument.h"
#include "HTMLElementFactory.h"
#include "HTMLFrameOwnerElement.h"
#include "HTMLHeadElement.h"
#include "HTMLIFrameElement.h"
#include "HTMLLinkElement.h"
#include "HTMLMapElement.h"
#include "HTMLNameCollection.h"
#include "HTMLNames.h"
#include "HTMLParserIdioms.h"
#include "HTMLStyleElement.h"
#include "HTMLTitleElement.h"
#include "HTTPParsers.h"
#include "HitTestRequest.h"
#include "HitTestResult.h"
#include "IconController.h"
#include "ImageLoader.h"
#include "InspectorCounters.h"
#include "InspectorInstrumentation.h"
#include "Language.h"
#include "Logging.h"
#include "MediaCanStartListener.h"
#include "MediaQueryList.h"
#include "MediaQueryMatcher.h"
#include "MouseEventWithHitTestResults.h"
#include "NameNodeList.h"
#include "NamedFlowCollection.h"
#include "NestingLevelIncrementer.h"
#include "NodeFilter.h"
#include "NodeIterator.h"
#include "NodeRareData.h"
#include "NodeTraversal.h"
#include "NodeWithIndex.h"
#include "Page.h"
#include "PageConsole.h"
#include "PageGroup.h"
#include "PageTransitionEvent.h"
#include "PlatformKeyboardEvent.h"
#include "PlatformLocale.h"
#include "PlugInsResources.h"
#include "PluginDocument.h"
#include "PointerLockController.h"
#include "PopStateEvent.h"
#include "ProcessingInstruction.h"
#include "QualifiedName.h"
#include "RegisteredEventListener.h"
#include "RenderArena.h"
#include "RenderNamedFlowThread.h"
#include "RenderTextControl.h"
#include "RenderView.h"
#include "RenderWidget.h"
#include "ResourceLoader.h"
#include "RuntimeEnabledFeatures.h"
#include "SchemeRegistry.h"
#include "ScopedEventQueue.h"
#include "ScriptCallStack.h"
#include "ScriptController.h"
#include "ScriptElement.h"
#include "ScriptEventListener.h"
#include "ScriptRunner.h"
#include "ScriptSourceCode.h"
#include "ScriptValue.h"
#include "ScrollingCoordinator.h"
#include "SecurityOrigin.h"
#include "SecurityPolicy.h"
#include "SegmentedString.h"
#include "SelectorQuery.h"
#include "Settings.h"
#include "ShadowRoot.h"
#include "StylePropertySet.h"
#include "StyleResolver.h"
#include "StyleSheetContents.h"
#include "StyleSheetList.h"
#include "TextResourceDecoder.h"
#include "Timer.h"
#include "TransformSource.h"
#include "TreeWalker.h"
#include "UserActionElementSet.h"
#include "UserContentURLPattern.h"
#include "VisitedLinkState.h"
#include "WebKitNamedFlow.h"
#include "XMLDocumentParser.h"
#include "XMLHttpRequest.h"
#include "XMLNSNames.h"
#include "XMLNames.h"
#include "XPathEvaluator.h"
#include "XPathExpression.h"
#include "XPathNSResolver.h"
#include "XPathResult.h"
#include "htmlediting.h"
#include <wtf/CurrentTime.h>
#include <wtf/HashFunctions.h>
#include <wtf/MainThread.h>
#include <wtf/PassRefPtr.h>
#include <wtf/StdLibExtras.h>
#include <wtf/text/StringBuffer.h>

#if USE(ACCELERATED_COMPOSITING)
#include "RenderLayerCompositor.h"
#endif

#if ENABLE(SHARED_WORKERS)
#include "SharedWorkerRepository.h"
#endif

#if ENABLE(XSLT)
#include "XSLTProcessor.h"
#endif

#if ENABLE(SVG)
#include "SVGDocumentExtensions.h"
#include "SVGElementFactory.h"
#include "SVGNames.h"
#include "SVGSVGElement.h"
#include "SVGStyleElement.h"
#endif

#if ENABLE(TOUCH_EVENTS)
#include "TouchList.h"
#endif

#if ENABLE(MATHML)
#include "MathMLElement.h"
#include "MathMLElementFactory.h"
#include "MathMLNames.h"
#endif

#if ENABLE(FULLSCREEN_API)
#include "RenderFullScreen.h"
#endif

#if ENABLE(REQUEST_ANIMATION_FRAME)
#include "RequestAnimationFrameCallback.h"
#include "ScriptedAnimationController.h"
#endif

#if ENABLE(MICRODATA)
#include "MicroDataItemList.h"
#include "NodeRareData.h"
#endif

#if ENABLE(LINK_PRERENDER)
#include "Prerenderer.h"
#endif

#if ENABLE(TEXT_AUTOSIZING)
#include "TextAutosizer.h"
#endif

#if ENABLE(CSP_NEXT)
#include "DOMSecurityPolicy.h"
#endif

#if ENABLE(VIDEO_TRACK)
#include "CaptionUserPreferences.h"
#endif

using namespace std;
using namespace WTF;
using namespace Unicode;

namespace WebCore {

using namespace HTMLNames;

// #define INSTRUMENT_LAYOUT_SCHEDULING 1

static const unsigned cMaxWriteRecursionDepth = 21;

// This amount of time must have elapsed before we will even consider scheduling a layout without a delay.
// FIXME: For faster machines this value can really be lowered to 200.  250 is adequate, but a little high
// for dual G5s. :)
static const int cLayoutScheduleThreshold = 250;

// DOM Level 2 says (letters added):
//
// a) Name start characters must have one of the categories Ll, Lu, Lo, Lt, Nl.
// b) Name characters other than Name-start characters must have one of the categories Mc, Me, Mn, Lm, or Nd.
// c) Characters in the compatibility area (i.e. with character code greater than #xF900 and less than #xFFFE) are not allowed in XML names.
// d) Characters which have a font or compatibility decomposition (i.e. those with a "compatibility formatting tag" in field 5 of the database -- marked by field 5 beginning with a "<") are not allowed.
// e) The following characters are treated as name-start characters rather than name characters, because the property file classifies them as Alphabetic: [#x02BB-#x02C1], #x0559, #x06E5, #x06E6.
// f) Characters #x20DD-#x20E0 are excluded (in accordance with Unicode, section 5.14).
// g) Character #x00B7 is classified as an extender, because the property list so identifies it.
// h) Character #x0387 is added as a name character, because #x00B7 is its canonical equivalent.
// i) Characters ':' and '_' are allowed as name-start characters.
// j) Characters '-' and '.' are allowed as name characters.
//
// It also contains complete tables. If we decide it's better, we could include those instead of the following code.

static inline bool isValidNameStart(UChar32 c)
{
    // rule (e) above
    if ((c >= 0x02BB && c <= 0x02C1) || c == 0x559 || c == 0x6E5 || c == 0x6E6)
        return true;

    // rule (i) above
    if (c == ':' || c == '_')
        return true;

    // rules (a) and (f) above
    const uint32_t nameStartMask = Letter_Lowercase | Letter_Uppercase | Letter_Other | Letter_Titlecase | Number_Letter;
    if (!(Unicode::category(c) & nameStartMask))
        return false;

    // rule (c) above
    if (c >= 0xF900 && c < 0xFFFE)
        return false;

    // rule (d) above
    DecompositionType decompType = decompositionType(c);
    if (decompType == DecompositionFont || decompType == DecompositionCompat)
        return false;

    return true;
}

static inline bool isValidNamePart(UChar32 c)
{
    // rules (a), (e), and (i) above
    if (isValidNameStart(c))
        return true;

    // rules (g) and (h) above
    if (c == 0x00B7 || c == 0x0387)
        return true;

    // rule (j) above
    if (c == '-' || c == '.')
        return true;

    // rules (b) and (f) above
    const uint32_t otherNamePartMask = Mark_NonSpacing | Mark_Enclosing | Mark_SpacingCombining | Letter_Modifier | Number_DecimalDigit;
    if (!(Unicode::category(c) & otherNamePartMask))
        return false;

    // rule (c) above
    if (c >= 0xF900 && c < 0xFFFE)
        return false;

    // rule (d) above
    DecompositionType decompType = decompositionType(c);
    if (decompType == DecompositionFont || decompType == DecompositionCompat)
        return false;

    return true;
}

static bool shouldInheritSecurityOriginFromOwner(const KURL& url)
{
    // http://www.whatwg.org/specs/web-apps/current-work/#origin-0
    //
    // If a Document has the address "about:blank"
    //     The origin of the Document is the origin it was assigned when its browsing context was created.
    //
    // Note: We generalize this to all "blank" URLs and invalid URLs because we
    // treat all of these URLs as about:blank.
    //
    return url.isEmpty() || url.isBlankURL();
}

static Widget* widgetForNode(Node* focusedNode)
{
    if (!focusedNode)
        return 0;
    RenderObject* renderer = focusedNode->renderer();
    if (!renderer || !renderer->isWidget())
        return 0;
    return toRenderWidget(renderer)->widget();
}

static bool acceptsEditingFocus(Node* node)
{
    ASSERT(node);
    ASSERT(node->rendererIsEditable());

    Node* root = node->rootEditableElement();
    Frame* frame = node->document()->frame();
    if (!frame || !root)
        return false;

    return frame->editor().shouldBeginEditing(rangeOfContents(root).get());
}

static bool canAccessAncestor(const SecurityOrigin* activeSecurityOrigin, Frame* targetFrame)
{
    // targetFrame can be 0 when we're trying to navigate a top-level frame
    // that has a 0 opener.
    if (!targetFrame)
        return false;

    const bool isLocalActiveOrigin = activeSecurityOrigin->isLocal();
    for (Frame* ancestorFrame = targetFrame; ancestorFrame; ancestorFrame = ancestorFrame->tree()->parent()) {
        Document* ancestorDocument = ancestorFrame->document();
        // FIXME: Should be an ASSERT? Frames should alway have documents.
        if (!ancestorDocument)
            return true;

        const SecurityOrigin* ancestorSecurityOrigin = ancestorDocument->securityOrigin();
        if (activeSecurityOrigin->canAccess(ancestorSecurityOrigin))
            return true;
        
        // Allow file URL descendant navigation even when allowFileAccessFromFileURLs is false.
        // FIXME: It's a bit strange to special-case local origins here. Should we be doing
        // something more general instead?
        if (isLocalActiveOrigin && ancestorSecurityOrigin->isLocal())
            return true;
    }

    return false;
}

static void printNavigationErrorMessage(Frame* frame, const KURL& activeURL, const char* reason)
{
    String message = "Unsafe JavaScript attempt to initiate navigation for frame with URL '" + frame->document()->url().string() + "' from frame with URL '" + activeURL.string() + "'. " + reason + "\n";

    // FIXME: should we print to the console of the document performing the navigation instead?
    frame->document()->domWindow()->printErrorMessage(message);
}

static HashSet<Document*>* documentsThatNeedStyleRecalc = 0;

uint64_t Document::s_globalTreeVersion = 0;

static const double timeBeforeThrowingAwayStyleResolverAfterLastUseInSeconds = 30;

Document::Document(Frame* frame, const KURL& url, unsigned documentClasses)
    : ContainerNode(0, CreateDocument)
    , TreeScope(this)
    , m_styleResolverThrowawayTimer(this, &Document::styleResolverThrowawayTimerFired, timeBeforeThrowingAwayStyleResolverAfterLastUseInSeconds)
    , m_activeParserCount(0)
    , m_contextFeatures(ContextFeatures::defaultSwitch())
    , m_compatibilityMode(NoQuirksMode)
    , m_compatibilityModeLocked(false)
    , m_domTreeVersion(++s_globalTreeVersion)
    , m_mutationObserverTypes(0)
    , m_styleSheetCollection(DocumentStyleSheetCollection::create(this))
    , m_visitedLinkState(VisitedLinkState::create(this))
    , m_readyState(Complete)
    , m_styleRecalcTimer(this, &Document::styleRecalcTimerFired)
    , m_pendingStyleRecalcShouldForce(false)
    , m_frameElementsShouldIgnoreScrolling(false)
    , m_containsValidityStyleRules(false)
    , m_updateFocusAppearanceRestoresSelection(false)
    , m_ignoreDestructiveWriteCount(0)
    , m_titleSetExplicitly(false)
    , m_updateFocusAppearanceTimer(this, &Document::updateFocusAppearanceTimerFired)
    , m_loadEventFinished(false)
    , m_startTime(currentTime())
    , m_overMinimumLayoutThreshold(false)
    , m_scriptRunner(ScriptRunner::create(this))
    , m_xmlVersion("1.0")
    , m_xmlStandalone(StandaloneUnspecified)
    , m_hasXMLDeclaration(0)
    , m_savedRenderer(0)
    , m_designMode(inherit)
#if ENABLE(DASHBOARD_SUPPORT) || ENABLE(DRAGGABLE_REGION)
    , m_hasAnnotatedRegions(false)
    , m_annotatedRegionsDirty(false)
#endif
    , m_createRenderers(true)
    , m_inPageCache(false)
    , m_accessKeyMapValid(false)
    , m_documentClasses(documentClasses)
    , m_isViewSource(false)
    , m_sawElementsInKnownNamespaces(false)
    , m_isSrcdocDocument(false)
    , m_renderer(0)
    , m_eventQueue(DocumentEventQueue::create(this))
    , m_weakFactory(this)
    , m_idAttributeName(idAttr)
#if ENABLE(FULLSCREEN_API)
    , m_areKeysEnabledInFullScreen(0)
    , m_fullScreenRenderer(0)
    , m_fullScreenChangeDelayTimer(this, &Document::fullScreenChangeDelayTimerFired)
    , m_isAnimatingFullScreen(false)
#endif
    , m_loadEventDelayCount(0)
    , m_loadEventDelayTimer(this, &Document::loadEventDelayTimerFired)
    , m_referrerPolicy(ReferrerPolicyDefault)
    , m_directionSetOnDocumentElement(false)
    , m_writingModeSetOnDocumentElement(false)
    , m_writeRecursionIsTooDeep(false)
    , m_writeRecursionDepth(0)
    , m_wheelEventHandlerCount(0)
    , m_lastHandledUserGestureTimestamp(0)
    , m_pendingTasksTimer(this, &Document::pendingTasksTimerFired)
    , m_scheduledTasksAreSuspended(false)
    , m_visualUpdatesAllowed(true)
    , m_visualUpdatesSuppressionTimer(this, &Document::visualUpdatesSuppressionTimerFired)
    , m_sharedObjectPoolClearTimer(this, &Document::sharedObjectPoolClearTimerFired)
#ifndef NDEBUG
    , m_didDispatchViewportPropertiesChanged(false)
#endif
#if ENABLE(TEMPLATE_ELEMENT)
    , m_templateDocumentHost(0)
#endif
#if ENABLE(FONT_LOAD_EVENTS)
    , m_fontloader(0)
#endif
    , m_didAssociateFormControlsTimer(this, &Document::didAssociateFormControlsTimerFired)
    , m_hasInjectedPlugInsScript(false)
{
    m_printing = false;
    m_paginatedForScreen = false;

    m_ignoreAutofocus = false;

    m_frame = frame;
    if (m_frame)
        provideContextFeaturesToDocumentFrom(this, m_frame->page());

    // We depend on the url getting immediately set in subframes, but we
    // also depend on the url NOT getting immediately set in opened windows.
    // See fast/dom/early-frame-url.html
    // and fast/dom/location-new-window-no-crash.html, respectively.
    // FIXME: Can/should we unify this behavior?
    if ((frame && frame->ownerElement()) || !url.isEmpty())
        setURL(url);

    m_markers = adoptPtr(new DocumentMarkerController);

    if (m_frame)
        m_cachedResourceLoader = m_frame->loader()->activeDocumentLoader()->cachedResourceLoader();
    if (!m_cachedResourceLoader)
        m_cachedResourceLoader = CachedResourceLoader::create(0);
    m_cachedResourceLoader->setDocument(this);

#if ENABLE(LINK_PRERENDER)
    m_prerenderer = Prerenderer::create(this);
#endif
#if ENABLE(TEXT_AUTOSIZING)
    m_textAutosizer = TextAutosizer::create(this);
#endif
    m_visuallyOrdered = false;
    m_bParsing = false;
    m_wellFormed = false;

    m_textColor = Color::black;
    m_listenerTypes = 0;
    m_inStyleRecalc = false;
    m_closeAfterStyleRecalc = false;

    m_gotoAnchorNeededAfterStylesheetsLoad = false;

    m_didCalculateStyleResolver = false;
    m_ignorePendingStylesheets = false;
    m_needsNotifyRemoveAllPendingStylesheet = false;
    m_hasNodesWithPlaceholderStyle = false;
    m_pendingSheetLayout = NoLayoutWithPendingSheets;

    m_cssTarget = 0;

    resetLinkColor();
    resetVisitedLinkColor();
    resetActiveLinkColor();

    m_processingLoadEvent = false;
    
    initSecurityContext();
    initDNSPrefetch();

    static int docID = 0;
    m_docID = docID++;

    for (unsigned i = 0; i < WTF_ARRAY_LENGTH(m_nodeListCounts); i++)
        m_nodeListCounts[i] = 0;

    InspectorCounters::incrementCounter(InspectorCounters::DocumentCounter);
}

static void histogramMutationEventUsage(const unsigned short& listenerTypes)
{
    HistogramSupport::histogramEnumeration("DOMAPI.PerDocumentMutationEventUsage.DOMSubtreeModified", static_cast<bool>(listenerTypes & Document::DOMSUBTREEMODIFIED_LISTENER), 2);
    HistogramSupport::histogramEnumeration("DOMAPI.PerDocumentMutationEventUsage.DOMNodeInserted", static_cast<bool>(listenerTypes & Document::DOMNODEINSERTED_LISTENER), 2);
    HistogramSupport::histogramEnumeration("DOMAPI.PerDocumentMutationEventUsage.DOMNodeRemoved", static_cast<bool>(listenerTypes & Document::DOMNODEREMOVED_LISTENER), 2);
    HistogramSupport::histogramEnumeration("DOMAPI.PerDocumentMutationEventUsage.DOMNodeRemovedFromDocument", static_cast<bool>(listenerTypes & Document::DOMNODEREMOVEDFROMDOCUMENT_LISTENER), 2);
    HistogramSupport::histogramEnumeration("DOMAPI.PerDocumentMutationEventUsage.DOMNodeInsertedIntoDocument", static_cast<bool>(listenerTypes & Document::DOMNODEINSERTEDINTODOCUMENT_LISTENER), 2);
    HistogramSupport::histogramEnumeration("DOMAPI.PerDocumentMutationEventUsage.DOMCharacterDataModified", static_cast<bool>(listenerTypes & Document::DOMCHARACTERDATAMODIFIED_LISTENER), 2);
}

#if ENABLE(FULLSCREEN_API)
static bool isAttributeOnAllOwners(const WebCore::QualifiedName& attribute, const WebCore::QualifiedName& prefixedAttribute, const HTMLFrameOwnerElement* owner)
{
    if (!owner)
        return true;
    do {
        if (!(owner->hasAttribute(attribute) || owner->hasAttribute(prefixedAttribute)))
            return false;
    } while ((owner = owner->document()->ownerElement()));
    return true;
}
#endif

Document::~Document()
{
    ASSERT(!renderer());
    ASSERT(!m_inPageCache);
    ASSERT(!m_savedRenderer);
    ASSERT(m_ranges.isEmpty());
    ASSERT(!m_styleRecalcTimer.isActive());
    ASSERT(!m_parentTreeScope);
    ASSERT(!hasGuardRefCount());

#if ENABLE(TEMPLATE_ELEMENT)
    if (m_templateDocument)
        m_templateDocument->setTemplateDocumentHost(0); // balanced in templateDocument().
#endif

#if ENABLE(TOUCH_EVENT_TRACKING)
    if (Document* ownerDocument = this->ownerDocument())
        ownerDocument->didRemoveEventTargetNode(this);
#endif
    // FIXME: Should we reset m_domWindow when we detach from the Frame?
    if (m_domWindow)
        m_domWindow->resetUnlessSuspendedForPageCache();

    m_scriptRunner.clear();

    histogramMutationEventUsage(m_listenerTypes);

    removeAllEventListeners();

    // Currently we believe that Document can never outlive the parser.
    // Although the Document may be replaced synchronously, DocumentParsers
    // generally keep at least one reference to an Element which would in turn
    // has a reference to the Document.  If you hit this ASSERT, then that
    // assumption is wrong.  DocumentParser::detach() should ensure that even
    // if the DocumentParser outlives the Document it won't cause badness.
    ASSERT(!m_parser || m_parser->refCount() == 1);
    detachParser();

    m_renderArena.clear();

    if (this == topDocument())
        clearAXObjectCache();

    m_decoder = 0;

    if (m_styleSheetList)
        m_styleSheetList->detachFromDocument();

    m_styleSheetCollection.clear();

    if (m_elemSheet)
        m_elemSheet->clearOwnerNode();

    clearStyleResolver(); // We need to destory CSSFontSelector before destroying m_cachedResourceLoader.

    // It's possible for multiple Documents to end up referencing the same CachedResourceLoader (e.g., SVGImages
    // load the initial empty document and the SVGDocument with the same DocumentLoader).
    if (m_cachedResourceLoader->document() == this)
        m_cachedResourceLoader->setDocument(0);
    m_cachedResourceLoader.clear();

    // We must call clearRareData() here since a Document class inherits TreeScope
    // as well as Node. See a comment on TreeScope.h for the reason.
    if (hasRareData())
        clearRareData();

    ASSERT(!m_listsInvalidatedAtDocument.size());

    for (unsigned i = 0; i < WTF_ARRAY_LENGTH(m_nodeListCounts); i++)
        ASSERT(!m_nodeListCounts[i]);

    clearDocumentScope();

    InspectorCounters::decrementCounter(InspectorCounters::DocumentCounter);
}

void Document::dispose()
{
    ASSERT(!m_deletionHasBegun);
    // We must make sure not to be retaining any of our children through
    // these extra pointers or we will create a reference cycle.
    m_docType = 0;
    m_focusedNode = 0;
    m_hoverNode = 0;
    m_activeElement = 0;
    m_titleElement = 0;
    m_documentElement = 0;
    m_contextFeatures = ContextFeatures::defaultSwitch();
    m_userActionElements.documentDidRemoveLastRef();
#if ENABLE(FULLSCREEN_API)
    m_fullScreenElement = 0;
    m_fullScreenElementStack.clear();
#endif

    detachParser();

#if ENABLE(CUSTOM_ELEMENTS)
    m_registry.clear();
#endif

    // removeDetachedChildren() doesn't always unregister IDs,
    // so tear down scope information upfront to avoid having stale references in the map.
    destroyTreeScopeData();
    removeDetachedChildren();

    m_markers->detach();

    m_cssCanvasElements.clear();

#if ENABLE(REQUEST_ANIMATION_FRAME)
    clearScriptedAnimationController();
#endif
}

Element* Document::getElementById(const AtomicString& id) const
{
    return TreeScope::getElementById(id);
}

Element* Document::getElementByAccessKey(const String& key)
{
    if (key.isEmpty())
        return 0;
    if (!m_accessKeyMapValid) {
        buildAccessKeyMap(this);
        m_accessKeyMapValid = true;
    }
    return m_elementsByAccessKey.get(key.impl());
}

void Document::buildAccessKeyMap(TreeScope* scope)
{
    ASSERT(scope);
    Node* rootNode = scope->rootNode();
    for (Element* element = ElementTraversal::firstWithin(rootNode); element; element = ElementTraversal::next(element, rootNode)) {
        const AtomicString& accessKey = element->getAttribute(accesskeyAttr);
        if (!accessKey.isEmpty())
            m_elementsByAccessKey.set(accessKey.impl(), element);

        if (ShadowRoot* root = element->shadowRoot())
            buildAccessKeyMap(root);
    }
}

void Document::invalidateAccessKeyMap()
{
    m_accessKeyMapValid = false;
    m_elementsByAccessKey.clear();
}

SelectorQueryCache* Document::selectorQueryCache()
{
    if (!m_selectorQueryCache)
        m_selectorQueryCache = adoptPtr(new SelectorQueryCache());
    return m_selectorQueryCache.get();
}

MediaQueryMatcher* Document::mediaQueryMatcher()
{
    if (!m_mediaQueryMatcher)
        m_mediaQueryMatcher = MediaQueryMatcher::create(this);
    return m_mediaQueryMatcher.get();
}

void Document::setCompatibilityMode(CompatibilityMode mode)
{
    if (m_compatibilityModeLocked || mode == m_compatibilityMode)
        return;
    bool wasInQuirksMode = inQuirksMode();
    m_compatibilityMode = mode;
    selectorQueryCache()->invalidate();
    if (inQuirksMode() != wasInQuirksMode) {
        // All user stylesheets have to reparse using the different mode.
        m_styleSheetCollection->clearPageUserSheet();
        m_styleSheetCollection->invalidateInjectedStyleSheetCache();
    }
}

String Document::compatMode() const
{
    return inQuirksMode() ? "BackCompat" : "CSS1Compat";
}

void Document::resetLinkColor()
{
    m_linkColor = Color(0, 0, 238);
}

void Document::resetVisitedLinkColor()
{
    m_visitedLinkColor = Color(85, 26, 139);    
}

void Document::resetActiveLinkColor()
{
    m_activeLinkColor.setNamedColor("red");
}

void Document::setDocType(PassRefPtr<DocumentType> docType)
{
    // This should never be called more than once.
    ASSERT(!m_docType || !docType);
    m_docType = docType;
    if (m_docType) {
        this->adoptIfNeeded(m_docType.get());
#if ENABLE(LEGACY_VIEWPORT_ADAPTION)
        if (m_docType->publicId().startsWith("-//wapforum//dtd xhtml mobile 1.", /* caseSensitive */ false))
            processViewport("width=device-width, height=device-height", ViewportArguments::XHTMLMobileProfile);
#endif
    }
    // Doctype affects the interpretation of the stylesheets.
    clearStyleResolver();
}

DOMImplementation* Document::implementation()
{
    if (!m_implementation)
        m_implementation = DOMImplementation::create(this);
    return m_implementation.get();
}

bool Document::hasManifest() const
{
    return documentElement() && documentElement()->hasTagName(htmlTag) && documentElement()->hasAttribute(manifestAttr);
}

void Document::childrenChanged(bool changedByParser, Node* beforeChange, Node* afterChange, int childCountDelta)
{
    ContainerNode::childrenChanged(changedByParser, beforeChange, afterChange, childCountDelta);
    
    Element* newDocumentElement = ElementTraversal::firstWithin(this);
    if (newDocumentElement == m_documentElement)
        return;
    m_documentElement = newDocumentElement;
    // The root style used for media query matching depends on the document element.
    clearStyleResolver();
}

PassRefPtr<Element> Document::createElement(const AtomicString& name, ExceptionCode& ec)
{
    if (!isValidName(name)) {
        ec = INVALID_CHARACTER_ERR;
        return 0;
    }

    if (isXHTMLDocument())
        return HTMLElementFactory::createHTMLElement(QualifiedName(nullAtom, name, xhtmlNamespaceURI), this, 0, false);

    return createElement(QualifiedName(nullAtom, name, nullAtom), false);
}

#if ENABLE(CUSTOM_ELEMENTS)
PassRefPtr<Element> Document::createElement(const AtomicString& localName, const AtomicString& typeExtension, ExceptionCode& ec)
{
    if (!isValidName(localName)) {
        ec = INVALID_CHARACTER_ERR;
        return 0;
    }

    if (m_registry) {
        if (PassRefPtr<Element> created = m_registry->createElement(QualifiedName(nullAtom, localName, xhtmlNamespaceURI), typeExtension))
            return created;
    }

    return setTypeExtension(createElement(localName, ec), typeExtension);
}

PassRefPtr<Element> Document::createElementNS(const AtomicString& namespaceURI, const String& qualifiedName, const AtomicString& typeExtension, ExceptionCode& ec)
{
    String prefix, localName;
    if (!parseQualifiedName(qualifiedName, prefix, localName, ec))
        return 0;

    QualifiedName qName(prefix, localName, namespaceURI);
    if (!hasValidNamespaceForElements(qName)) {
        ec = NAMESPACE_ERR;
        return 0;
    }

    if (m_registry) {
        if (PassRefPtr<Element> created = m_registry->createElement(qName, typeExtension))
            return created;
    }

    return setTypeExtension(createElementNS(namespaceURI, qualifiedName, ec), typeExtension);
}

PassRefPtr<CustomElementConstructor> Document::registerElement(WebCore::ScriptState* state, const AtomicString& name, ExceptionCode& ec)
{
    return registerElement(state, name, Dictionary(), ec);
}

PassRefPtr<CustomElementConstructor> Document::registerElement(WebCore::ScriptState* state, const AtomicString& name, const Dictionary& options, ExceptionCode& ec)
{
    if (!isHTMLDocument() && !isXHTMLDocument()) {
        ec = NOT_SUPPORTED_ERR;
        return 0;
    }

    if (!m_registry)
        m_registry = adoptRef(new CustomElementRegistry(this));
    return m_registry->registerElement(state, name, options, ec);
}

void Document::didCreateCustomElement(Element* element, CustomElementConstructor* constructor)
{
    // m_registry is cleared Document::dispose() and can be null here.
    if (m_registry)
        m_registry->didCreateElement(element);
}
#endif // ENABLE(CUSTOM_ELEMENTS)

PassRefPtr<DocumentFragment> Document::createDocumentFragment()
{
    return DocumentFragment::create(document());
}

PassRefPtr<Text> Document::createTextNode(const String& data)
{
    return Text::create(this, data);
}

PassRefPtr<Comment> Document::createComment(const String& data)
{
    return Comment::create(this, data);
}

PassRefPtr<CDATASection> Document::createCDATASection(const String& data, ExceptionCode& ec)
{
    if (isHTMLDocument()) {
        ec = NOT_SUPPORTED_ERR;
        return 0;
    }
    return CDATASection::create(this, data);
}

PassRefPtr<ProcessingInstruction> Document::createProcessingInstruction(const String& target, const String& data, ExceptionCode& ec)
{
    if (!isValidName(target)) {
        ec = INVALID_CHARACTER_ERR;
        return 0;
    }
    if (isHTMLDocument()) {
        ec = NOT_SUPPORTED_ERR;
        return 0;
    }
    return ProcessingInstruction::create(this, target, data);
}

PassRefPtr<EntityReference> Document::createEntityReference(const String& name, ExceptionCode& ec)
{
    if (!isValidName(name)) {
        ec = INVALID_CHARACTER_ERR;
        return 0;
    }
    if (isHTMLDocument()) {
        ec = NOT_SUPPORTED_ERR;
        return 0;
    }
    return EntityReference::create(this, name);
}

PassRefPtr<Text> Document::createEditingTextNode(const String& text)
{
    return Text::createEditingText(this, text);
}

PassRefPtr<CSSStyleDeclaration> Document::createCSSStyleDeclaration()
{
    return MutableStylePropertySet::create()->ensureCSSStyleDeclaration();
}

PassRefPtr<Node> Document::importNode(Node* importedNode, bool deep, ExceptionCode& ec)
{
    ec = 0;
    
    if (!importedNode) {
        ec = NOT_SUPPORTED_ERR;
        return 0;
    }

    switch (importedNode->nodeType()) {
    case TEXT_NODE:
        return createTextNode(importedNode->nodeValue());
    case CDATA_SECTION_NODE:
        return createCDATASection(importedNode->nodeValue(), ec);
    case ENTITY_REFERENCE_NODE:
        return createEntityReference(importedNode->nodeName(), ec);
    case PROCESSING_INSTRUCTION_NODE:
        return createProcessingInstruction(importedNode->nodeName(), importedNode->nodeValue(), ec);
    case COMMENT_NODE:
        return createComment(importedNode->nodeValue());
    case ELEMENT_NODE: {
        Element* oldElement = toElement(importedNode);
        // FIXME: The following check might be unnecessary. Is it possible that
        // oldElement has mismatched prefix/namespace?
        if (!hasValidNamespaceForElements(oldElement->tagQName())) {
            ec = NAMESPACE_ERR;
            return 0;
        }
        RefPtr<Element> newElement = createElement(oldElement->tagQName(), false);

        newElement->cloneDataFromElement(*oldElement);

        if (deep) {
            for (Node* oldChild = oldElement->firstChild(); oldChild; oldChild = oldChild->nextSibling()) {
                RefPtr<Node> newChild = importNode(oldChild, true, ec);
                if (ec)
                    return 0;
                newElement->appendChild(newChild.release(), ec);
                if (ec)
                    return 0;
            }
        }

        return newElement.release();
    }
    case ATTRIBUTE_NODE:
        return Attr::create(this, QualifiedName(nullAtom, static_cast<Attr*>(importedNode)->name(), nullAtom), static_cast<Attr*>(importedNode)->value());
    case DOCUMENT_FRAGMENT_NODE: {
        if (importedNode->isShadowRoot()) {
            // ShadowRoot nodes should not be explicitly importable.
            // Either they are imported along with their host node, or created implicitly.
            break;
        }
        DocumentFragment* oldFragment = static_cast<DocumentFragment*>(importedNode);
        RefPtr<DocumentFragment> newFragment = createDocumentFragment();
        if (deep) {
            for (Node* oldChild = oldFragment->firstChild(); oldChild; oldChild = oldChild->nextSibling()) {
                RefPtr<Node> newChild = importNode(oldChild, true, ec);
                if (ec)
                    return 0;
                newFragment->appendChild(newChild.release(), ec);
                if (ec)
                    return 0;
            }
        }
        
        return newFragment.release();
    }
    case ENTITY_NODE:
    case NOTATION_NODE:
        // FIXME: It should be possible to import these node types, however in DOM3 the DocumentType is readonly, so there isn't much sense in doing that.
        // Ability to add these imported nodes to a DocumentType will be considered for addition to a future release of the DOM.
    case DOCUMENT_NODE:
    case DOCUMENT_TYPE_NODE:
    case XPATH_NAMESPACE_NODE:
        break;
    }
    ec = NOT_SUPPORTED_ERR;
    return 0;
}


PassRefPtr<Node> Document::adoptNode(PassRefPtr<Node> source, ExceptionCode& ec)
{
    if (!source) {
        ec = NOT_SUPPORTED_ERR;
        return 0;
    }

    if (source->isReadOnlyNode()) {
        ec = NO_MODIFICATION_ALLOWED_ERR;
        return 0;
    }

    EventQueueScope scope;

    switch (source->nodeType()) {
    case ENTITY_NODE:
    case NOTATION_NODE:
    case DOCUMENT_NODE:
    case DOCUMENT_TYPE_NODE:
    case XPATH_NAMESPACE_NODE:
        ec = NOT_SUPPORTED_ERR;
        return 0;            
    case ATTRIBUTE_NODE: {                   
        Attr* attr = static_cast<Attr*>(source.get());
        if (attr->ownerElement())
            attr->ownerElement()->removeAttributeNode(attr, ec);
        attr->setSpecified(true);
        break;
    }       
    default:
        if (source->isShadowRoot()) {
            // ShadowRoot cannot disconnect itself from the host node.
            ec = HIERARCHY_REQUEST_ERR;
            return 0;
        }

        if (source->isFrameOwnerElement()) {
            HTMLFrameOwnerElement* frameOwnerElement = toFrameOwnerElement(source.get());
            if (frame() && frame()->tree()->isDescendantOf(frameOwnerElement->contentFrame())) {
                ec = HIERARCHY_REQUEST_ERR;
                return 0;
            }
        }
        if (source->parentNode()) {
            source->parentNode()->removeChild(source.get(), ec);
            if (ec)
                return 0;
        }
    }

    this->adoptIfNeeded(source.get());

    return source;
}

bool Document::hasValidNamespaceForElements(const QualifiedName& qName)
{
    // These checks are from DOM Core Level 2, createElementNS
    // http://www.w3.org/TR/DOM-Level-2-Core/core.html#ID-DocCrElNS
    if (!qName.prefix().isEmpty() && qName.namespaceURI().isNull()) // createElementNS(null, "html:div")
        return false;
    if (qName.prefix() == xmlAtom && qName.namespaceURI() != XMLNames::xmlNamespaceURI) // createElementNS("http://www.example.com", "xml:lang")
        return false;

    // Required by DOM Level 3 Core and unspecified by DOM Level 2 Core:
    // http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407/core.html#ID-DocCrElNS
    // createElementNS("http://www.w3.org/2000/xmlns/", "foo:bar"), createElementNS(null, "xmlns:bar")
    if ((qName.prefix() == xmlnsAtom && qName.namespaceURI() != XMLNSNames::xmlnsNamespaceURI) || (qName.prefix() != xmlnsAtom && qName.namespaceURI() == XMLNSNames::xmlnsNamespaceURI))
        return false;

    return true;
}

bool Document::hasValidNamespaceForAttributes(const QualifiedName& qName)
{
    // Spec: DOM Level 2 Core: http://www.w3.org/TR/DOM-Level-2-Core/core.html#ID-ElSetAttrNS
    if (qName.prefix().isEmpty() && qName.localName() == xmlnsAtom) {
        // Note: The case of an "xmlns" qualified name with a namespace of
        // xmlnsNamespaceURI is specifically allowed (See <http://www.w3.org/2000/xmlns/>).
        return qName.namespaceURI() == XMLNSNames::xmlnsNamespaceURI;
    }
    return hasValidNamespaceForElements(qName);
}

// FIXME: This should really be in a possible ElementFactory class
PassRefPtr<Element> Document::createElement(const QualifiedName& qName, bool createdByParser)
{
    RefPtr<Element> e;

    // FIXME: Use registered namespaces and look up in a hash to find the right factory.
    if (qName.namespaceURI() == xhtmlNamespaceURI)
        e = HTMLElementFactory::createHTMLElement(qName, this, 0, createdByParser);
#if ENABLE(SVG)
    else if (qName.namespaceURI() == SVGNames::svgNamespaceURI)
        e = SVGElementFactory::createSVGElement(qName, this, createdByParser);
#endif
#if ENABLE(MATHML)
    else if (qName.namespaceURI() == MathMLNames::mathmlNamespaceURI)
        e = MathMLElementFactory::createMathMLElement(qName, this, createdByParser);
#endif

    if (e)
        m_sawElementsInKnownNamespaces = true;
    else
        e = Element::create(qName, document());

    // <image> uses imgTag so we need a special rule.
    ASSERT((qName.matches(imageTag) && e->tagQName().matches(imgTag) && e->tagQName().prefix() == qName.prefix()) || qName == e->tagQName());

    return e.release();
}

bool Document::regionBasedColumnsEnabled() const
{
    return settings() && settings()->regionBasedColumnsEnabled(); 
}

bool Document::cssStickyPositionEnabled() const
{
    return settings() && settings()->cssStickyPositionEnabled(); 
}

bool Document::cssRegionsEnabled() const
{
    return RuntimeEnabledFeatures::cssRegionsEnabled(); 
}

bool Document::cssCompositingEnabled() const
{
    return RuntimeEnabledFeatures::cssCompositingEnabled();
}

bool Document::cssGridLayoutEnabled() const
{
    return settings() && settings()->cssGridLayoutEnabled();
}

#if ENABLE(CSS_REGIONS)

PassRefPtr<DOMNamedFlowCollection> Document::webkitGetNamedFlows()
{
    if (!cssRegionsEnabled() || !renderer())
        return 0;

    updateStyleIfNeeded();

    return namedFlows()->createCSSOMSnapshot();
}

#endif

NamedFlowCollection* Document::namedFlows()
{
    if (!m_namedFlows)
        m_namedFlows = NamedFlowCollection::create(this);

    return m_namedFlows.get();
}

PassRefPtr<Element> Document::createElementNS(const String& namespaceURI, const String& qualifiedName, ExceptionCode& ec)
{
    String prefix, localName;
    if (!parseQualifiedName(qualifiedName, prefix, localName, ec))
        return 0;

    QualifiedName qName(prefix, localName, namespaceURI);
    if (!hasValidNamespaceForElements(qName)) {
        ec = NAMESPACE_ERR;
        return 0;
    }

    return createElement(qName, false);
}

String Document::readyState() const
{
    DEFINE_STATIC_LOCAL(const String, loading, (ASCIILiteral("loading")));
    DEFINE_STATIC_LOCAL(const String, interactive, (ASCIILiteral("interactive")));
    DEFINE_STATIC_LOCAL(const String, complete, (ASCIILiteral("complete")));

    switch (m_readyState) {
    case Loading:
        return loading;
    case Interactive:
        return interactive;
    case Complete:
        return complete;
    }

    ASSERT_NOT_REACHED();
    return String();
}

void Document::setReadyState(ReadyState readyState)
{
    if (readyState == m_readyState)
        return;

    switch (readyState) {
    case Loading:
        if (!m_documentTiming.domLoading)
            m_documentTiming.domLoading = monotonicallyIncreasingTime();
        break;
    case Interactive:
        if (!m_documentTiming.domInteractive)
            m_documentTiming.domInteractive = monotonicallyIncreasingTime();
        break;
    case Complete:
        if (!m_documentTiming.domComplete)
            m_documentTiming.domComplete = monotonicallyIncreasingTime();
        break;
    }

    m_readyState = readyState;
    dispatchEvent(Event::create(eventNames().readystatechangeEvent, false, false));
    
    if (settings() && settings()->suppressesIncrementalRendering())
        setVisualUpdatesAllowed(readyState);
}

void Document::setVisualUpdatesAllowed(ReadyState readyState)
{
    ASSERT(settings() && settings()->suppressesIncrementalRendering());
    switch (readyState) {
    case Loading:
        ASSERT(!m_visualUpdatesSuppressionTimer.isActive());
        ASSERT(m_visualUpdatesAllowed);
        m_visualUpdatesSuppressionTimer.startOneShot(settings()->incrementalRenderingSuppressionTimeoutInSeconds());
        setVisualUpdatesAllowed(false);
        break;
    case Interactive:
        ASSERT(m_visualUpdatesSuppressionTimer.isActive() || m_visualUpdatesAllowed);
        break;
    case Complete:
        if (m_visualUpdatesSuppressionTimer.isActive()) {
            ASSERT(!m_visualUpdatesAllowed);
            m_visualUpdatesSuppressionTimer.stop();
            setVisualUpdatesAllowed(true);
        } else
            ASSERT(m_visualUpdatesAllowed);
        break;
    }
}
    
void Document::setVisualUpdatesAllowed(bool visualUpdatesAllowed)
{
    if (m_visualUpdatesAllowed == visualUpdatesAllowed)
        return;

    m_visualUpdatesAllowed = visualUpdatesAllowed;

    if (!visualUpdatesAllowed)
        return;

    FrameView* frameView = view();
    bool needsLayout = frameView && renderer() && (frameView->layoutPending() || renderer()->needsLayout());
    if (needsLayout)
        updateLayout();

    if (Page* page = this->page()) {
        if (frame() == page->mainFrame())
            frameView->addPaintPendingMilestones(DidFirstPaintAfterSuppressedIncrementalRendering);
        if (page->requestedLayoutMilestones() & DidFirstLayoutAfterSuppressedIncrementalRendering)
            frame()->loader()->didLayout(DidFirstLayoutAfterSuppressedIncrementalRendering);
    }

#if USE(ACCELERATED_COMPOSITING)
    if (view())
        view()->updateCompositingLayersAfterLayout();
#endif

    if (RenderView* renderView = this->renderView())
        renderView->repaintViewAndCompositedLayers();
}

void Document::visualUpdatesSuppressionTimerFired(Timer<Document>*)
{
    ASSERT(!m_visualUpdatesAllowed);
    setVisualUpdatesAllowed(true);
}

String Document::encoding() const
{
    if (TextResourceDecoder* d = decoder())
        return d->encoding().domName();
    return String();
}

String Document::defaultCharset() const
{
    if (Settings* settings = this->settings())
        return settings->defaultTextEncodingName();
    return String();
}

void Document::setCharset(const String& charset)
{
    if (!decoder())
        return;
    decoder()->setEncoding(charset, TextResourceDecoder::UserChosenEncoding);
}

void Document::setContentLanguage(const String& language)
{
    if (m_contentLanguage == language)
        return;
    m_contentLanguage = language;

    // Recalculate style so language is used when selecting the initial font.
    styleResolverChanged(DeferRecalcStyle);
}

void Document::setXMLVersion(const String& version, ExceptionCode& ec)
{
    if (!implementation()->hasFeature("XML", String())) {
        ec = NOT_SUPPORTED_ERR;
        return;
    }

    if (!XMLDocumentParser::supportsXMLVersion(version)) {
        ec = NOT_SUPPORTED_ERR;
        return;
    }

    m_xmlVersion = version;
}

void Document::setXMLStandalone(bool standalone, ExceptionCode& ec)
{
    if (!implementation()->hasFeature("XML", String())) {
        ec = NOT_SUPPORTED_ERR;
        return;
    }

    m_xmlStandalone = standalone ? Standalone : NotStandalone;
}

void Document::setDocumentURI(const String& uri)
{
    // This property is read-only from JavaScript, but writable from Objective-C.
    m_documentURI = uri;
    updateBaseURL();
}

KURL Document::baseURI() const
{
    return m_baseURL;
}

void Document::setContent(const String& content)
{
    open();
    // FIXME: This should probably use insert(), but that's (intentionally)
    // not implemented for the XML parser as it's normally synonymous with
    // document.write(). append() will end up yielding, but close() will
    // pump the tokenizer syncrhonously and finish the parse.
    m_parser->pinToMainThread();
    m_parser->append(content.impl());
    close();
}

String Document::suggestedMIMEType() const
{
    if (isXHTMLDocument())
        return "application/xhtml+xml";
    if (isSVGDocument())
        return "image/svg+xml";
    if (xmlStandalone())
        return "text/xml";
    if (isHTMLDocument())
        return "text/html";

    if (DocumentLoader* documentLoader = loader())
        return documentLoader->responseMIMEType();
    return String();
}

Element* Document::elementFromPoint(int x, int y) const
{
    if (!renderer())
        return 0;

    return TreeScope::elementFromPoint(x, y);
}

PassRefPtr<Range> Document::caretRangeFromPoint(int x, int y)
{
    if (!renderer())
        return 0;
    LayoutPoint localPoint;
    Node* node = nodeFromPoint(this, x, y, &localPoint);
    if (!node)
        return 0;

    Node* shadowAncestorNode = ancestorInThisScope(node);
    if (shadowAncestorNode != node) {
        unsigned offset = shadowAncestorNode->nodeIndex();
        ContainerNode* container = shadowAncestorNode->parentNode();
        return Range::create(this, container, offset, container, offset);
    }

    RenderObject* renderer = node->renderer();
    if (!renderer)
        return 0;
    VisiblePosition visiblePosition = renderer->positionForPoint(localPoint);
    if (visiblePosition.isNull())
        return 0;

    Position rangeCompliantPosition = visiblePosition.deepEquivalent().parentAnchoredEquivalent();
    return Range::create(this, rangeCompliantPosition, rangeCompliantPosition);
}

/*
 * Performs three operations:
 *  1. Convert control characters to spaces
 *  2. Trim leading and trailing spaces
 *  3. Collapse internal whitespace.
 */
template <typename CharacterType>
static inline StringWithDirection canonicalizedTitle(Document* document, const StringWithDirection& titleWithDirection)
{
    const String& title = titleWithDirection.string();
    const CharacterType* characters = title.getCharacters<CharacterType>();
    unsigned length = title.length();
    unsigned i;

    StringBuffer<CharacterType> buffer(length);
    unsigned builderIndex = 0;

    // Skip leading spaces and leading characters that would convert to spaces
    for (i = 0; i < length; ++i) {
        CharacterType c = characters[i];
        if (!(c <= 0x20 || c == 0x7F))
            break;
    }

    if (i == length)
        return StringWithDirection();

    // Replace control characters with spaces, and backslashes with currency symbols, and collapse whitespace.
    bool previousCharWasWS = false;
    for (; i < length; ++i) {
        CharacterType c = characters[i];
        if (c <= 0x20 || c == 0x7F || (WTF::Unicode::category(c) & (WTF::Unicode::Separator_Line | WTF::Unicode::Separator_Paragraph))) {
            if (previousCharWasWS)
                continue;
            buffer[builderIndex++] = ' ';
            previousCharWasWS = true;
        } else {
            buffer[builderIndex++] = c;
            previousCharWasWS = false;
        }
    }

    // Strip trailing spaces
    while (builderIndex > 0) {
        --builderIndex;
        if (buffer[builderIndex] != ' ')
            break;
    }

    if (!builderIndex && buffer[builderIndex] == ' ')
        return StringWithDirection();

    buffer.shrink(builderIndex + 1);

    // Replace the backslashes with currency symbols if the encoding requires it.
    document->displayBufferModifiedByEncoding(buffer.characters(), buffer.length());
    
    return StringWithDirection(String::adopt(buffer), titleWithDirection.direction());
}

void Document::updateTitle(const StringWithDirection& title)
{
    if (m_rawTitle == title)
        return;

    m_rawTitle = title;

    if (m_rawTitle.string().isEmpty())
        m_title = StringWithDirection();
    else {
        if (m_rawTitle.string().is8Bit())
            m_title = canonicalizedTitle<LChar>(this, m_rawTitle);
        else
            m_title = canonicalizedTitle<UChar>(this, m_rawTitle);
    }
    if (Frame* f = frame())
        f->loader()->setTitle(m_title);
}

void Document::setTitle(const String& title)
{
    // Title set by JavaScript -- overrides any title elements.
    m_titleSetExplicitly = true;
    if (!isHTMLDocument() && !isXHTMLDocument())
        m_titleElement = 0;
    else if (!m_titleElement) {
        if (HTMLElement* headElement = head()) {
            m_titleElement = createElement(titleTag, false);
            headElement->appendChild(m_titleElement, ASSERT_NO_EXCEPTION);
        }
    }

    // The DOM API has no method of specifying direction, so assume LTR.
    updateTitle(StringWithDirection(title, LTR));

    if (m_titleElement) {
        ASSERT(m_titleElement->hasTagName(titleTag));
        if (m_titleElement->hasTagName(titleTag))
            static_cast<HTMLTitleElement*>(m_titleElement.get())->setText(title);
    }
}

void Document::setTitleElement(const StringWithDirection& title, Element* titleElement)
{
    if (titleElement != m_titleElement) {
        if (m_titleElement || m_titleSetExplicitly)
            // Only allow the first title element to change the title -- others have no effect.
            return;
        m_titleElement = titleElement;
    }

    updateTitle(title);
}

void Document::removeTitle(Element* titleElement)
{
    if (m_titleElement != titleElement)
        return;

    m_titleElement = 0;
    m_titleSetExplicitly = false;

    // Update title based on first title element in the head, if one exists.
    if (HTMLElement* headElement = head()) {
        for (Node* e = headElement->firstChild(); e; e = e->nextSibling())
            if (e->hasTagName(titleTag)) {
                HTMLTitleElement* titleElement = static_cast<HTMLTitleElement*>(e);
                setTitleElement(titleElement->textWithDirection(), titleElement);
                break;
            }
    }

    if (!m_titleElement)
        updateTitle(StringWithDirection());
}

#if ENABLE(PAGE_VISIBILITY_API)
PageVisibilityState Document::visibilityState() const
{
    // The visibility of the document is inherited from the visibility of the
    // page. If there is no page associated with the document, we will assume
    // that the page is hidden, as specified by the spec:
    // http://dvcs.w3.org/hg/webperf/raw-file/tip/specs/PageVisibility/Overview.html#dom-document-hidden
    if (!m_frame || !m_frame->page())
        return PageVisibilityStateHidden;
    return m_frame->page()->visibilityState();
}

String Document::webkitVisibilityState() const
{
    return pageVisibilityStateString(visibilityState());
}

bool Document::webkitHidden() const
{
    return visibilityState() != PageVisibilityStateVisible;
}

void Document::dispatchVisibilityStateChangeEvent()
{
    dispatchEvent(Event::create(eventNames().webkitvisibilitychangeEvent, false, false));
}
#endif

#if ENABLE(CSP_NEXT)
DOMSecurityPolicy* Document::securityPolicy()
{
    if (!m_domSecurityPolicy)
        m_domSecurityPolicy = DOMSecurityPolicy::create(this);
    return m_domSecurityPolicy.get();
}
#endif

String Document::nodeName() const
{
    return "#document";
}

Node::NodeType Document::nodeType() const
{
    return DOCUMENT_NODE;
}

FormController* Document::formController()
{
    if (!m_formController)
        m_formController = FormController::create();
    return m_formController.get();
}

Vector<String> Document::formElementsState() const
{
    if (!m_formController)
        return Vector<String>();
    return m_formController->formElementsState();
}

void Document::setStateForNewFormElements(const Vector<String>& stateVector)
{
    if (!stateVector.size() && !m_formController)
        return;
    formController()->setStateForNewFormElements(stateVector);
}

FrameView* Document::view() const
{
    return m_frame ? m_frame->view() : 0;
}

Page* Document::page() const
{
    return m_frame ? m_frame->page() : 0;    
}

Settings* Document::settings() const
{
    return m_frame ? m_frame->settings() : 0;
}

PassRefPtr<Range> Document::createRange()
{
    return Range::create(this);
}

PassRefPtr<NodeIterator> Document::createNodeIterator(Node* root, unsigned whatToShow, 
    PassRefPtr<NodeFilter> filter, bool expandEntityReferences, ExceptionCode& ec)
{
    if (!root) {
        ec = NOT_SUPPORTED_ERR;
        return 0;
    }
    return NodeIterator::create(root, whatToShow, filter, expandEntityReferences);
}

PassRefPtr<TreeWalker> Document::createTreeWalker(Node* root, unsigned whatToShow, 
    PassRefPtr<NodeFilter> filter, bool expandEntityReferences, ExceptionCode& ec)
{
    if (!root) {
        ec = NOT_SUPPORTED_ERR;
        return 0;
    }
    return TreeWalker::create(root, whatToShow, filter, expandEntityReferences);
}

void Document::scheduleForcedStyleRecalc()
{
    m_pendingStyleRecalcShouldForce = true;
    scheduleStyleRecalc();
}

void Document::scheduleStyleRecalc()
{
    if (shouldDisplaySeamlesslyWithParent()) {
        // When we're seamless, our parent document manages our style recalcs.
        ownerElement()->setNeedsStyleRecalc();
        ownerElement()->document()->scheduleStyleRecalc();
        return;
    }

    if (m_styleRecalcTimer.isActive() || inPageCache())
        return;

    ASSERT(childNeedsStyleRecalc() || m_pendingStyleRecalcShouldForce);

    if (!documentsThatNeedStyleRecalc)
        documentsThatNeedStyleRecalc = new HashSet<Document*>;
    documentsThatNeedStyleRecalc->add(this);
    
    // FIXME: Why on earth is this here? This is clearly misplaced.
    invalidateAccessKeyMap();
    
    m_styleRecalcTimer.startOneShot(0);

    InspectorInstrumentation::didScheduleStyleRecalculation(this);
}

void Document::unscheduleStyleRecalc()
{
    ASSERT(!childNeedsStyleRecalc());

    if (documentsThatNeedStyleRecalc)
        documentsThatNeedStyleRecalc->remove(this);

    m_styleRecalcTimer.stop();
    m_pendingStyleRecalcShouldForce = false;
}

bool Document::hasPendingStyleRecalc() const
{
    return m_styleRecalcTimer.isActive() && !m_inStyleRecalc;
}

bool Document::hasPendingForcedStyleRecalc() const
{
    return m_styleRecalcTimer.isActive() && m_pendingStyleRecalcShouldForce;
}

void Document::styleRecalcTimerFired(Timer<Document>*)
{
    updateStyleIfNeeded();
}

bool Document::childNeedsAndNotInStyleRecalc()
{
    return childNeedsStyleRecalc() && !m_inStyleRecalc;
}

void Document::recalcStyle(StyleChange change)
{
    // we should not enter style recalc while painting
    ASSERT(!view() || !view()->isPainting());
    if (view() && view()->isPainting())
        return;
    
    if (m_inStyleRecalc)
        return; // Guard against re-entrancy. -dwh

    // FIXME: We should update style on our ancestor chain before proceeding (especially for seamless),
    // however doing so currently causes several tests to crash, as Frame::setDocument calls Document::attach
    // before setting the DOMWindow on the Frame, or the SecurityOrigin on the document. The attach, in turn
    // resolves style (here) and then when we resolve style on the parent chain, we may end up
    // re-attaching our containing iframe, which when asked HTMLFrameElementBase::isURLAllowed
    // hits a null-dereference due to security code always assuming the document has a SecurityOrigin.

    if (m_styleSheetCollection->needsUpdateActiveStylesheetsOnStyleRecalc())
        m_styleSheetCollection->updateActiveStyleSheets(DocumentStyleSheetCollection::FullUpdate);

    InspectorInstrumentationCookie cookie = InspectorInstrumentation::willRecalculateStyle(this);

    if (m_elemSheet && m_elemSheet->contents()->usesRemUnits())
        m_styleSheetCollection->setUsesRemUnit(true);

    m_inStyleRecalc = true;
    {
        PostAttachCallbackDisabler disabler(this);
        WidgetHierarchyUpdatesSuspensionScope suspendWidgetHierarchyUpdates;

        RefPtr<FrameView> frameView = view();
        if (frameView) {
            frameView->pauseScheduledEvents();
            frameView->beginDeferredRepaints();
        }

        ASSERT(!renderer() || renderArena());
        if (!renderer() || !renderArena())
            goto bailOut;

        if (m_pendingStyleRecalcShouldForce)
            change = Force;

        // Recalculating the root style (on the document) is not needed in the common case.
        if ((change == Force) || (shouldDisplaySeamlesslyWithParent() && (change >= Inherit))) {
            // style selector may set this again during recalc
            m_hasNodesWithPlaceholderStyle = false;
            
            RefPtr<RenderStyle> documentStyle = StyleResolver::styleForDocument(this, m_styleResolver ? m_styleResolver->fontSelector() : 0);
            StyleChange ch = Node::diff(documentStyle.get(), renderer()->style(), this);
            if (ch != NoChange)
                renderer()->setStyle(documentStyle.release());
        }

        for (Node* n = firstChild(); n; n = n->nextSibling()) {
            if (!n->isElementNode())
                continue;
            Element* element = toElement(n);
            if (change >= Inherit || element->childNeedsStyleRecalc() || element->needsStyleRecalc())
                element->recalcStyle(change);
        }

#if USE(ACCELERATED_COMPOSITING)
        if (view())
            view()->updateCompositingLayersAfterStyleChange();
#endif

    bailOut:
        clearNeedsStyleRecalc();
        clearChildNeedsStyleRecalc();
        unscheduleStyleRecalc();

        m_inStyleRecalc = false;

        // Pseudo element removal and similar may only work with these flags still set. Reset them after the style recalc.
        if (m_styleResolver)
            m_styleSheetCollection->resetCSSFeatureFlags();

        if (frameView) {
            frameView->resumeScheduledEvents();
            frameView->endDeferredRepaints();
        }
    }

    // If we wanted to call implicitClose() during recalcStyle, do so now that we're finished.
    if (m_closeAfterStyleRecalc) {
        m_closeAfterStyleRecalc = false;
        implicitClose();
    }

    InspectorInstrumentation::didRecalculateStyle(cookie);
}

void Document::updateStyleIfNeeded()
{
    ASSERT(isMainThread());
    ASSERT(!view() || (!view()->isInLayout() && !view()->isPainting()));
    
    if ((!m_pendingStyleRecalcShouldForce && !childNeedsStyleRecalc()) || inPageCache())
        return;

    AnimationUpdateBlock animationUpdateBlock(m_frame ? m_frame->animation() : 0);
    recalcStyle(NoChange);
}

void Document::updateStyleForAllDocuments()
{
    ASSERT(isMainThread());
    if (!documentsThatNeedStyleRecalc)
        return;

    while (documentsThatNeedStyleRecalc->size()) {
        HashSet<Document*>::iterator it = documentsThatNeedStyleRecalc->begin();
        Document* doc = *it;
        documentsThatNeedStyleRecalc->remove(doc);
        doc->updateStyleIfNeeded();
    }
}

void Document::updateLayout()
{
    ASSERT(isMainThread());

    FrameView* frameView = view();
    if (frameView && frameView->isInLayout()) {
        // View layout should not be re-entrant.
        ASSERT_NOT_REACHED();
        return;
    }

    if (Element* oe = ownerElement())
        oe->document()->updateLayout();

    updateStyleIfNeeded();

    StackStats::LayoutCheckPoint layoutCheckPoint;

    // Only do a layout if changes have occurred that make it necessary.      
    if (frameView && renderer() && (frameView->layoutPending() || renderer()->needsLayout()))
        frameView->layout();
}

// FIXME: This is a bad idea and needs to be removed eventually.
// Other browsers load stylesheets before they continue parsing the web page.
// Since we don't, we can run JavaScript code that needs answers before the
// stylesheets are loaded. Doing a layout ignoring the pending stylesheets
// lets us get reasonable answers. The long term solution to this problem is
// to instead suspend JavaScript execution.
void Document::updateLayoutIgnorePendingStylesheets()
{
    bool oldIgnore = m_ignorePendingStylesheets;
    
    if (!haveStylesheetsLoaded()) {
        m_ignorePendingStylesheets = true;
        // FIXME: We are willing to attempt to suppress painting with outdated style info only once.  Our assumption is that it would be
        // dangerous to try to stop it a second time, after page content has already been loaded and displayed
        // with accurate style information.  (Our suppression involves blanking the whole page at the
        // moment.  If it were more refined, we might be able to do something better.)
        // It's worth noting though that this entire method is a hack, since what we really want to do is
        // suspend JS instead of doing a layout with inaccurate information.
        HTMLElement* bodyElement = body();
        if (bodyElement && !bodyElement->renderer() && m_pendingSheetLayout == NoLayoutWithPendingSheets) {
            m_pendingSheetLayout = DidLayoutWithPendingSheets;
            styleResolverChanged(RecalcStyleImmediately);
        } else if (m_hasNodesWithPlaceholderStyle)
            // If new nodes have been added or style recalc has been done with style sheets still pending, some nodes 
            // may not have had their real style calculated yet. Normally this gets cleaned when style sheets arrive 
            // but here we need up-to-date style immediately.
            recalcStyle(Force);
    }

    updateLayout();

    m_ignorePendingStylesheets = oldIgnore;
}

PassRefPtr<RenderStyle> Document::styleForElementIgnoringPendingStylesheets(Element* element)
{
    ASSERT_ARG(element, element->document() == this);

    bool oldIgnore = m_ignorePendingStylesheets;
    m_ignorePendingStylesheets = true;
    RefPtr<RenderStyle> style = ensureStyleResolver()->styleForElement(element, element->parentNode() ? element->parentNode()->computedStyle() : 0);
    m_ignorePendingStylesheets = oldIgnore;
    return style.release();
}

PassRefPtr<RenderStyle> Document::styleForPage(int pageIndex)
{
    RefPtr<RenderStyle> style = ensureStyleResolver()->styleForPage(pageIndex);
    return style.release();
}

bool Document::isPageBoxVisible(int pageIndex)
{
    RefPtr<RenderStyle> style = styleForPage(pageIndex);
    return style->visibility() != HIDDEN; // display property doesn't apply to @page.
}

void Document::pageSizeAndMarginsInPixels(int pageIndex, IntSize& pageSize, int& marginTop, int& marginRight, int& marginBottom, int& marginLeft)
{
    RefPtr<RenderStyle> style = styleForPage(pageIndex);
    RenderView* view = renderView();

    int width = pageSize.width();
    int height = pageSize.height();
    switch (style->pageSizeType()) {
    case PAGE_SIZE_AUTO:
        break;
    case PAGE_SIZE_AUTO_LANDSCAPE:
        if (width < height)
            std::swap(width, height);
        break;
    case PAGE_SIZE_AUTO_PORTRAIT:
        if (width > height)
            std::swap(width, height);
        break;
    case PAGE_SIZE_RESOLVED: {
        LengthSize size = style->pageSize();
        ASSERT(size.width().isFixed());
        ASSERT(size.height().isFixed());
        width = valueForLength(size.width(), 0, view);
        height = valueForLength(size.height(), 0, view);
        break;
    }
    default:
        ASSERT_NOT_REACHED();
    }
    pageSize = IntSize(width, height);

    // The percentage is calculated with respect to the width even for margin top and bottom.
    // http://www.w3.org/TR/CSS2/box.html#margin-properties
    marginTop = style->marginTop().isAuto() ? marginTop : intValueForLength(style->marginTop(), width, view);
    marginRight = style->marginRight().isAuto() ? marginRight : intValueForLength(style->marginRight(), width, view);
    marginBottom = style->marginBottom().isAuto() ? marginBottom : intValueForLength(style->marginBottom(), width, view);
    marginLeft = style->marginLeft().isAuto() ? marginLeft : intValueForLength(style->marginLeft(), width, view);
}

void Document::setIsViewSource(bool isViewSource)
{
    m_isViewSource = isViewSource;
    if (!m_isViewSource)
        return;

    setSecurityOrigin(SecurityOrigin::createUnique());
}

void Document::createStyleResolver()
{
    bool matchAuthorAndUserStyles = true;
    if (Settings* docSettings = settings())
        matchAuthorAndUserStyles = docSettings->authorAndUserStylesEnabled();
    m_styleResolver = adoptPtr(new StyleResolver(this, matchAuthorAndUserStyles));
    m_styleSheetCollection->combineCSSFeatureFlags();
}

void Document::clearStyleResolver()
{
    m_styleResolver.clear();
}

void Document::attach()
{
    ASSERT(!attached());
    ASSERT(!m_inPageCache);
    ASSERT(!m_axObjectCache || this != topDocument());

    if (!m_renderArena)
        m_renderArena = RenderArena::create();
    
    // Create the rendering tree
    setRenderer(new (m_renderArena.get()) RenderView(this));
#if USE(ACCELERATED_COMPOSITING)
    renderView()->setIsInWindow(true);
#endif

    recalcStyle(Force);

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

    ContainerNode::attach();

    setRenderer(render);
}

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

#if ENABLE(POINTER_LOCK)
    if (page())
        page()->pointerLockController()->documentDetached(this);
#endif

    if (this == topDocument())
        clearAXObjectCache();

    stopActiveDOMObjects();
    m_eventQueue->close();
#if ENABLE(FULLSCREEN_API)
    m_fullScreenChangeEventTargetQueue.clear();
    m_fullScreenErrorEventTargetQueue.clear();
#endif

#if ENABLE(REQUEST_ANIMATION_FRAME)
    clearScriptedAnimationController();
#endif

    RenderObject* render = renderer();

    documentWillBecomeInactive();

#if ENABLE(SHARED_WORKERS)
    SharedWorkerRepository::documentDetached(this);
#endif

    if (m_frame) {
        FrameView* view = m_frame->view();
        if (view)
            view->detachCustomScrollbars();

    }

    // indicate destruction mode,  i.e. attached() but renderer == 0
    setRenderer(0);
    
#if ENABLE(FULLSCREEN_API)
    if (m_fullScreenRenderer)
        setFullScreenRenderer(0);
#endif

    m_hoverNode = 0;
    m_focusedNode = 0;
    m_activeElement = 0;

    ContainerNode::detach();

    unscheduleStyleRecalc();

    if (render)
        render->destroy();

#if ENABLE(TOUCH_EVENTS)
    if (m_touchEventTargets && m_touchEventTargets->size() && parentDocument())
        parentDocument()->didRemoveEventTargetNode(this);
#endif

    // This is required, as our Frame might delete itself as soon as it detaches
    // us. However, this violates Node::detach() semantics, as it's never
    // possible to re-attach. Eventually Document::detach() should be renamed,
    // or this setting of the frame to 0 could be made explicit in each of the
    // callers of Document::detach().
    m_frame = 0;
    m_renderArena.clear();

    if (m_mediaQueryMatcher)
        m_mediaQueryMatcher->documentDestroyed();
}

void Document::prepareForDestruction()
{
    disconnectDescendantFrames();
    if (DOMWindow* window = this->domWindow())
        window->willDetachDocumentFromFrame();
    detach();
}

void Document::removeAllEventListeners()
{
    EventTarget::removeAllEventListeners();

    if (DOMWindow* domWindow = this->domWindow())
        domWindow->removeAllEventListeners();
    for (Node* node = firstChild(); node; node = NodeTraversal::next(node))
        node->removeAllEventListeners();
}

void Document::suspendActiveDOMObjects(ActiveDOMObject::ReasonForSuspension why)
{
    ScriptExecutionContext::suspendActiveDOMObjects(why);
}

void Document::resumeActiveDOMObjects()
{
    ScriptExecutionContext::resumeActiveDOMObjects();
}

void Document::clearAXObjectCache()
{
    ASSERT(topDocument() == this);
    // Clear the cache member variable before calling delete because attempts
    // are made to access it during destruction.
    m_axObjectCache.clear();
}

AXObjectCache* Document::existingAXObjectCache() const
{
    if (!AXObjectCache::accessibilityEnabled())
        return 0;

    // If the renderer is gone then we are in the process of destruction.
    // This method will be called before m_frame = 0.
    if (!topDocument()->renderer())
        return 0;

    return topDocument()->m_axObjectCache.get();
}

AXObjectCache* Document::axObjectCache() const
{
    if (!AXObjectCache::accessibilityEnabled())
        return 0;
    
    // 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).
    Document* topDocument = this->topDocument();

    // If the document has already been detached, do not make a new axObjectCache.
    if (!topDocument->renderer())
        return 0;

    ASSERT(topDocument == this || !m_axObjectCache);
    if (!topDocument->m_axObjectCache)
        topDocument->m_axObjectCache = adoptPtr(new AXObjectCache(topDocument));
    return topDocument->m_axObjectCache.get();
}

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

PassRefPtr<DocumentParser> Document::createParser()
{
    // FIXME: this should probably pass the frame instead
    return XMLDocumentParser::create(this, view());
}

ScriptableDocumentParser* Document::scriptableDocumentParser() const
{
    return parser() ? parser()->asScriptableDocumentParser() : 0;
}

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

    if (m_frame) {
        if (ScriptableDocumentParser* parser = scriptableDocumentParser()) {
            if (parser->isParsing()) {
                // FIXME: HTML5 doesn't tell us to check this, it might not be correct.
                if (parser->isExecutingScript())
                    return;

                if (!parser->wasCreatedByScript() && parser->hasInsertionPoint())
                    return;
            }
        }

        if (m_frame->loader()->state() == FrameStateProvisional)
            m_frame->loader()->stopAllLoaders();
    }

    removeAllEventListeners();
    implicitOpen();
    if (ScriptableDocumentParser* parser = scriptableDocumentParser())
        parser->setWasCreatedByScript(true);

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

void Document::detachParser()
{
    if (!m_parser)
        return;
    m_parser->detach();
    m_parser.clear();
}

void Document::cancelParsing()
{
    if (!m_parser)
        return;

    // We have to clear the parser 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
    detachParser();
    explicitClose();
}

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

    removeChildren();

    setCompatibilityMode(NoQuirksMode);

    // Documents rendered seamlessly should start out requiring a stylesheet
    // collection update in order to ensure they inherit all the relevant data
    // from their parent.
    if (shouldDisplaySeamlesslyWithParent())
        styleResolverChanged(DeferRecalcStyle);

    m_parser = createParser();
    setParsing(true);
    setReadyState(Loading);
}

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 toHTMLElement(i);
        
        if (i->hasTagName(bodyTag) && !body)
            body = i;
    }
    return toHTMLElement(body);
}

void Document::setBody(PassRefPtr<HTMLElement> prpNewBody, ExceptionCode& ec)
{
    RefPtr<HTMLElement> newBody = prpNewBody;

    if (!newBody || !documentElement() || !newBody->hasTagName(bodyTag)) { 
        ec = HIERARCHY_REQUEST_ERR;
        return;
    }

    if (newBody->document() && newBody->document() != this) {
        ec = 0;
        RefPtr<Node> node = importNode(newBody.get(), true, ec);
        if (ec)
            return;
        
        newBody = toHTMLElement(node.get());
    }

    HTMLElement* b = body();
    if (!b)
        documentElement()->appendChild(newBody.release(), ec);
    else
        documentElement()->replaceChild(newBody.release(), 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()
{
    // FIXME: We should follow the specification more closely:
    //        http://www.whatwg.org/specs/web-apps/current-work/#dom-document-close

    if (!scriptableDocumentParser() || !scriptableDocumentParser()->wasCreatedByScript() || !scriptableDocumentParser()->isParsing())
        return;

    explicitClose();
}

void Document::explicitClose()
{
    if (RefPtr<DocumentParser> parser = m_parser)
        parser->finish();

    if (!m_frame) {
        // 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();
        return;
    }

    m_frame->loader()->checkCompleted();
}

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()->navigationScheduler()->locationChangePending();
    bool doload = !parsing() && m_parser && !m_processingLoadEvent && !wasLocationChangePending;
    
    if (!doload)
        return;

    // Call to dispatchWindowLoadEvent can blow us from underneath.
    RefPtr<Document> protect(this);

    m_processingLoadEvent = true;

    ScriptableDocumentParser* parser = scriptableDocumentParser();
    m_wellFormed = parser && parser->wellFormed();

    // We have to clear the parser, in case someone document.write()s from the
    // onLoad event handler, as in Radar 3206524.
    detachParser();

    // 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()->icon()->startLoader();
        f->animation()->startAnimationsIfNotSuspended(this);
    }

    ImageLoader::dispatchPendingBeforeLoadEvents();
    ImageLoader::dispatchPendingLoadEvents();
    ImageLoader::dispatchPendingErrorEvents();

    HTMLLinkElement::dispatchPendingLoadEvents();
    HTMLStyleElement::dispatchPendingLoadEvents();

#if ENABLE(SVG)
    // To align the HTML load event and the SVGLoad event for the outermost <svg> element, fire it from
    // here, instead of doing it from SVGElement::finishedParsingChildren (if externalResourcesRequired="false",
    // which is the default, for ='true' its fired at a later time, once all external resources finished loading).
    if (svgExtensions())
        accessSVGExtensions()->dispatchSVGLoadEventToOutermostSVGElements();
#endif

    dispatchWindowLoadEvent();
    enqueuePageshowEvent(PageshowEventNotPersisted);
    enqueuePopstateEvent(m_pendingStateObject ? m_pendingStateObject.release() : SerializedScriptValue::nullValue());
    
    if (f)
        f->loader()->handledOnloadEvents();
#ifdef INSTRUMENT_LAYOUT_SCHEDULING
    if (!ownerElement())
        printf("onload fired at %d\n", elapsedTime());
#endif

    // An event handler may have removed the frame
    if (!frame()) {
        m_processingLoadEvent = false;
        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()->navigationScheduler()->locationChangePending() && 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.        
        m_processingLoadEvent = false;
        view()->unscheduleRelayout();
        return;
    }

    frame()->loader()->checkCallImplicitClose();
    
    // We used to force a synchronous display and flush here.  This really isn't
    // necessary and can in fact be actively harmful if pages are loading at a rate of > 60fps
    // (if your platform is syncing flushes and limiting them to 60fps).
    m_overMinimumLayoutThreshold = true;
    if (!ownerElement() || (ownerElement()->renderer() && !ownerElement()->renderer()->needsLayout())) {
        updateStyleIfNeeded();
        
        // Always do a layout after loading if needed.
        if (view() && renderer() && (!renderer()->firstChild() || renderer()->needsLayout()))
            view()->layout();
    }

    m_processingLoadEvent = false;

#if PLATFORM(MAC)
    if (f && renderer() && AXObjectCache::accessibilityEnabled()) {
        // The AX cache may have been cleared at this point, but we need to make sure it contains an
        // AX object to send the notification to. getOrCreate will make sure that an valid AX object
        // exists in the cache (we ignore the return value because we don't need it here). This is 
        // only safe to call when a layout is not in progress, so it can not be used in postNotification.    
        axObjectCache()->getOrCreate(renderer());
        if (this == topDocument())
            axObjectCache()->postNotification(renderer(), AXObjectCache::AXLoadComplete, true);
        else {
            // AXLoadComplete can only be posted on the top document, so if it's a document
            // in an iframe that just finished loading, post AXLayoutComplete instead.
            axObjectCache()->postNotification(renderer(), AXObjectCache::AXLayoutComplete, true);
        }
    }
#endif

#if ENABLE(SVG)
    if (svgExtensions())
        accessSVGExtensions()->startAnimations();
#endif
}

void Document::setParsing(bool b)
{
    m_bParsing = b;

    if (m_bParsing && !m_sharedObjectPool)
        m_sharedObjectPool = DocumentSharedObjectPool::create();

    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));
}
    
bool Document::isLayoutTimerActive()
{
    return view() && view()->layoutPending() && !minimumLayoutDelay();
}

int Document::minimumLayoutDelay()
{
    if (m_overMinimumLayoutThreshold)
        return 0;
    
    int elapsed = elapsedTime();
    m_overMinimumLayoutThreshold = elapsed > cLayoutScheduleThreshold;
    
    // We'll want to schedule the timer to fire at the minimum layout threshold.
    return max(0, cLayoutScheduleThreshold - elapsed);
}

int Document::elapsedTime() const
{
    return static_cast<int>((currentTime() - m_startTime) * 1000);
}

void Document::write(const SegmentedString& text, Document* ownerDocument)
{
    NestingLevelIncrementer nestingLevelIncrementer(m_writeRecursionDepth);

    m_writeRecursionIsTooDeep = (m_writeRecursionDepth > 1) && m_writeRecursionIsTooDeep;
    m_writeRecursionIsTooDeep = (m_writeRecursionDepth > cMaxWriteRecursionDepth) || m_writeRecursionIsTooDeep;

    if (m_writeRecursionIsTooDeep)
       return;

#ifdef INSTRUMENT_LAYOUT_SCHEDULING
    if (!ownerElement())
        printf("Beginning a document.write at %d\n", elapsedTime());
#endif

    bool hasInsertionPoint = m_parser && m_parser->hasInsertionPoint();
    if (!hasInsertionPoint && m_ignoreDestructiveWriteCount)
        return;

    if (!hasInsertionPoint)
        open(ownerDocument);

    ASSERT(m_parser);
    m_parser->insert(text);

#ifdef INSTRUMENT_LAYOUT_SCHEDULING
    if (!ownerElement())
        printf("Ending a document.write at %d\n", elapsedTime());
#endif    
}

void Document::write(const String& text, Document* ownerDocument)
{
    write(SegmentedString(text), ownerDocument);
}

void Document::writeln(const String& text, Document* ownerDocument)
{
    write(text, ownerDocument);
    write("\n", ownerDocument);
}

const KURL& Document::virtualURL() const
{
    return m_url;
}

KURL Document::virtualCompleteURL(const String& url) const
{
    return completeURL(url);
}

double Document::minimumTimerInterval() const
{
    Page* p = page();
    if (!p)
        return ScriptExecutionContext::minimumTimerInterval();
    return p->settings()->minDOMTimerInterval();
}

double Document::timerAlignmentInterval() const
{
    Page* p = page();
    if (!p)
        return ScriptExecutionContext::timerAlignmentInterval();
    return p->settings()->domTimerAlignmentInterval();
}

EventTarget* Document::errorEventTarget()
{
    return domWindow();
}

void Document::logExceptionToConsole(const String& errorMessage, const String& sourceURL, int lineNumber, int columnNumber, PassRefPtr<ScriptCallStack> callStack)
{
    addMessage(JSMessageSource, ErrorMessageLevel, errorMessage, sourceURL, lineNumber, columnNumber, callStack);
}

void Document::setURL(const KURL& url)
{
    const KURL& newURL = url.isEmpty() ? blankURL() : url;
    if (newURL == m_url)
        return;

    m_url = newURL;
    m_documentURI = m_url.string();
    updateBaseURL();
    contextFeatures()->urlDidChange(this);
}

void Document::updateBaseURL()
{
    KURL oldBaseURL = m_baseURL;
    // DOM 3 Core: When the Document supports the feature "HTML" [DOM Level 2 HTML], the base URI is computed using
    // first the value of the href attribute of the HTML BASE element if any, and the value of the documentURI attribute
    // from the Document interface otherwise.
    if (!m_baseElementURL.isEmpty())
        m_baseURL = m_baseElementURL;
    else if (!m_baseURLOverride.isEmpty())
        m_baseURL = m_baseURLOverride;
    else {
        // The documentURI attribute is read-only from JavaScript, but writable from Objective C, so we need to retain
        // this fallback behavior. We use a null base URL, since the documentURI attribute is an arbitrary string
        // and DOM 3 Core does not specify how it should be resolved.
        m_baseURL = KURL(ParsedURLString, documentURI());
    }
    selectorQueryCache()->invalidate();

    if (!m_baseURL.isValid())
        m_baseURL = KURL();

    if (m_elemSheet) {
        // Element sheet is silly. It never contains anything.
        ASSERT(!m_elemSheet->contents()->ruleCount());
        bool usesRemUnits = m_elemSheet->contents()->usesRemUnits();
        m_elemSheet = CSSStyleSheet::createInline(this, m_baseURL);
        // FIXME: So we are not really the parser. The right fix is to eliminate the element sheet completely.
        m_elemSheet->contents()->parserSetUsesRemUnits(usesRemUnits);
    }

    if (!equalIgnoringFragmentIdentifier(oldBaseURL, m_baseURL)) {
        // Base URL change changes any relative visited links.
        // FIXME: There are other URLs in the tree that would need to be re-evaluated on dynamic base URL change. Style should be invalidated too.
        for (Element* element = ElementTraversal::firstWithin(this); element; element = ElementTraversal::next(element)) {
            if (element->hasTagName(aTag))
                static_cast<HTMLAnchorElement*>(element)->invalidateCachedVisitedLinkHash();
        }
    }
}

void Document::setBaseURLOverride(const KURL& url)
{
    m_baseURLOverride = url;
    updateBaseURL();
}

void Document::processBaseElement()
{
    // Find the first href attribute in a base element and the first target attribute in a base element.
    const AtomicString* href = 0;
    const AtomicString* target = 0;
    for (Element* element = ElementTraversal::firstWithin(this); element && (!href || !target); element = ElementTraversal::next(element)) {
        if (element->hasTagName(baseTag)) {
            if (!href) {
                const AtomicString& value = element->fastGetAttribute(hrefAttr);
                if (!value.isNull())
                    href = &value;
            }
            if (!target) {
                const AtomicString& value = element->fastGetAttribute(targetAttr);
                if (!value.isNull())
                    target = &value;
            }
        }
    }

    // FIXME: Since this doesn't share code with completeURL it may not handle encodings correctly.
    KURL baseElementURL;
    if (href) {
        String strippedHref = stripLeadingAndTrailingHTMLSpaces(*href);
        if (!strippedHref.isEmpty())
            baseElementURL = KURL(url(), strippedHref);
    }
    if (m_baseElementURL != baseElementURL && contentSecurityPolicy()->allowBaseURI(baseElementURL)) {
        m_baseElementURL = baseElementURL;
        updateBaseURL();
    }

    m_baseTarget = target ? *target : nullAtom;
}

String Document::userAgent(const KURL& url) const
{
    return frame() ? frame()->loader()->userAgent(url) : String();
}

void Document::disableEval(const String& errorMessage)
{
    if (!frame())
        return;

    frame()->script()->disableEval(errorMessage);
}

bool Document::canNavigate(Frame* targetFrame)
{
    if (!m_frame)
        return false;

    // FIXME: We shouldn't call this function without a target frame, but
    // fast/forms/submit-to-blank-multiple-times.html depends on this function
    // returning true when supplied with a 0 targetFrame.
    if (!targetFrame)
        return true;

    // Frame-busting is generally allowed, but blocked for sandboxed frames lacking the 'allow-top-navigation' flag.
    if (!isSandboxed(SandboxTopNavigation) && targetFrame == m_frame->tree()->top())
        return true;

    if (isSandboxed(SandboxNavigation)) {
        if (targetFrame->tree()->isDescendantOf(m_frame))
            return true;

        const char* reason = "The frame attempting navigation is sandboxed, and is therefore disallowed from navigating its ancestors.";
        if (isSandboxed(SandboxTopNavigation) && targetFrame == m_frame->tree()->top())
            reason = "The frame attempting navigation of the top-level window is sandboxed, but the 'allow-top-navigation' flag is not set.";

        printNavigationErrorMessage(targetFrame, url(), reason);
        return false;
    }

    // This is the normal case. A document can navigate its decendant frames,
    // or, more generally, a document can navigate a frame if the document is
    // in the same origin as any of that frame's ancestors (in the frame
    // hierarchy).
    //
    // See http://www.adambarth.com/papers/2008/barth-jackson-mitchell.pdf for
    // historical information about this security check.
    if (canAccessAncestor(securityOrigin(), targetFrame))
        return true;

    // Top-level frames are easier to navigate than other frames because they
    // display their URLs in the address bar (in most browsers). However, there
    // are still some restrictions on navigation to avoid nuisance attacks.
    // Specifically, a document can navigate a top-level frame if that frame
    // opened the document or if the document is the same-origin with any of
    // the top-level frame's opener's ancestors (in the frame hierarchy).
    //
    // In both of these cases, the document performing the navigation is in
    // some way related to the frame being navigate (e.g., by the "opener"
    // and/or "parent" relation). Requiring some sort of relation prevents a
    // document from navigating arbitrary, unrelated top-level frames.
    if (!targetFrame->tree()->parent()) {
        if (targetFrame == m_frame->loader()->opener())
            return true;

        if (canAccessAncestor(securityOrigin(), targetFrame->loader()->opener()))
            return true;
    }

    printNavigationErrorMessage(targetFrame, url(), "The frame attempting navigation is neither same-origin with the target, nor is it the target's parent or opener.");
    return false;
}

Frame* Document::findUnsafeParentScrollPropagationBoundary()
{
    Frame* currentFrame = m_frame;
    if (!currentFrame)
        return 0;

    Frame* ancestorFrame = currentFrame->tree()->parent();

    while (ancestorFrame) {
        if (!ancestorFrame->document()->securityOrigin()->canAccess(securityOrigin()))
            return currentFrame;
        currentFrame = ancestorFrame;
        ancestorFrame = ancestorFrame->tree()->parent();
    }
    return 0;
}


void Document::seamlessParentUpdatedStylesheets()
{
    styleResolverChanged(RecalcStyleImmediately);
}

void Document::didRemoveAllPendingStylesheet()
{
    m_needsNotifyRemoveAllPendingStylesheet = false;

    styleResolverChanged(RecalcStyleIfNeeded);

    if (ScriptableDocumentParser* parser = scriptableDocumentParser())
        parser->executeScriptsWaitingForStylesheets();

    if (m_gotoAnchorNeededAfterStylesheetsLoad && view())
        view()->scrollToFragment(m_url);
}

CSSStyleSheet* Document::elementSheet()
{
    if (!m_elemSheet)
        m_elemSheet = CSSStyleSheet::createInline(this, m_baseURL);
    return m_elemSheet.get();
}

int Document::nodeAbsIndex(Node *node)
{
    ASSERT(node->document() == this);

    int absIndex = 0;
    for (Node* n = node; n && n != this; n = NodeTraversal::previous(n))
        absIndex++;
    return absIndex;
}

Node* Document::nodeWithAbsIndex(int absIndex)
{
    Node* n = this;
    for (int i = 0; n && (i < absIndex); i++)
        n = NodeTraversal::next(n);
    return n;
}

void Document::processHttpEquiv(const String& equiv, const String& content)
{
    ASSERT(!equiv.isNull() && !content.isNull());

    Frame* frame = this->frame();

    if (equalIgnoringCase(equiv, "default-style")) {
        // The preferred style set has been overridden as per section 
        // 14.3.2 of the HTML4.0 specification.  We need to update the
        // sheet used variable and then update our style selector. 
        // For more info, see the test at:
        // http://www.hixie.ch/tests/evil/css/import/main/preferred.html
        // -dwh
        m_styleSheetCollection->setSelectedStylesheetSetName(content);
        m_styleSheetCollection->setPreferredStylesheetSetName(content);
        styleResolverChanged(DeferRecalcStyle);
    } else if (equalIgnoringCase(equiv, "refresh")) {
        double delay;
        String url;
        if (frame && parseHTTPRefresh(content, true, delay, url)) {
            if (url.isEmpty())
                url = m_url.string();
            else
                url = completeURL(url).string();
            frame->navigationScheduler()->scheduleRedirect(delay, url);
        }
    } else if (equalIgnoringCase(equiv, "set-cookie")) {
        // FIXME: make setCookie work on XML documents too; e.g. in case of <html:meta .....>
        if (isHTMLDocument()) {
            // Exception (for sandboxed documents) ignored.
            toHTMLDocument(this)->setCookie(content, IGNORE_EXCEPTION);
        }
    } else if (equalIgnoringCase(equiv, "content-language"))
        setContentLanguage(content);
    else if (equalIgnoringCase(equiv, "x-dns-prefetch-control"))
        parseDNSPrefetchControlHeader(content);
    else if (equalIgnoringCase(equiv, "x-frame-options")) {
        if (frame) {
            FrameLoader* frameLoader = frame->loader();
            unsigned long requestIdentifier = 0;
            if (frameLoader->activeDocumentLoader() && frameLoader->activeDocumentLoader()->mainResourceLoader())
                requestIdentifier = frameLoader->activeDocumentLoader()->mainResourceLoader()->identifier();
            if (frameLoader->shouldInterruptLoadForXFrameOptions(content, url(), requestIdentifier)) {
                String message = "Refused to display '" + url().elidedString() + "' in a frame because it set 'X-Frame-Options' to '" + content + "'.";
                frameLoader->stopAllLoaders();
                // Stopping the loader isn't enough, as we're already parsing the document; to honor the header's
                // intent, we must navigate away from the possibly partially-rendered document to a location that
                // doesn't inherit the parent's SecurityOrigin.
                frame->navigationScheduler()->scheduleLocationChange(securityOrigin(), SecurityOrigin::urlWithUniqueSecurityOrigin(), String());
                addConsoleMessage(SecurityMessageSource, ErrorMessageLevel, message, requestIdentifier);
            }
        }
    } else if (equalIgnoringCase(equiv, "content-security-policy"))
        contentSecurityPolicy()->didReceiveHeader(content, ContentSecurityPolicy::Enforce);
    else if (equalIgnoringCase(equiv, "content-security-policy-report-only"))
        contentSecurityPolicy()->didReceiveHeader(content, ContentSecurityPolicy::Report);
    else if (equalIgnoringCase(equiv, "x-webkit-csp"))
        contentSecurityPolicy()->didReceiveHeader(content, ContentSecurityPolicy::PrefixedEnforce);
    else if (equalIgnoringCase(equiv, "x-webkit-csp-report-only"))
        contentSecurityPolicy()->didReceiveHeader(content, ContentSecurityPolicy::PrefixedReport);
}

// Though isspace() considers \t and \v to be whitespace, Win IE doesn't.
static bool isSeparator(UChar c)
{
    return c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == '=' || c == ',' || c == '\0';
}

void Document::processArguments(const String& features, void* data, ArgumentsCallback callback)
{
    // Tread lightly in this code -- it was specifically designed to mimic Win IE's parsing behavior.
    int keyBegin, keyEnd;
    int valueBegin, valueEnd;

    int i = 0;
    int length = features.length();
    String buffer = features.lower();
    while (i < length) {
        // skip to first non-separator, but don't skip past the end of the string
        while (isSeparator(buffer[i])) {
            if (i >= length)
                break;
            i++;
        }
        keyBegin = i;

        // skip to first separator
        while (!isSeparator(buffer[i]))
            i++;
        keyEnd = i;

        // skip to first '=', but don't skip past a ',' or the end of the string
        while (buffer[i] != '=') {
            if (buffer[i] == ',' || i >= length)
                break;
            i++;
        }

        // skip to first non-separator, but don't skip past a ',' or the end of the string
        while (isSeparator(buffer[i])) {
            if (buffer[i] == ',' || i >= length)
                break;
            i++;
        }
        valueBegin = i;

        // skip to first separator
        while (!isSeparator(buffer[i]))
            i++;
        valueEnd = i;

        ASSERT_WITH_SECURITY_IMPLICATION(i <= length);

        String keyString = buffer.substring(keyBegin, keyEnd - keyBegin);
        String valueString = buffer.substring(valueBegin, valueEnd - valueBegin);
        callback(keyString, valueString, this, data);
    }
}

void Document::processViewport(const String& features, ViewportArguments::Type origin)
{
    ASSERT(!features.isNull());

    if (origin < m_viewportArguments.type)
        return;

    m_viewportArguments = ViewportArguments(origin);
    processArguments(features, (void*)&m_viewportArguments, &setViewportFeature);

    updateViewportArguments();
}

void Document::updateViewportArguments()
{
    if (page() && page()->mainFrame() == frame()) {
#ifndef NDEBUG
        m_didDispatchViewportPropertiesChanged = true;
#endif
        page()->chrome()->dispatchViewportPropertiesDidChange(m_viewportArguments);
    }
}

void Document::processReferrerPolicy(const String& policy)
{
    ASSERT(!policy.isNull());

    m_referrerPolicy = ReferrerPolicyDefault;

    if (equalIgnoringCase(policy, "never"))
        m_referrerPolicy = ReferrerPolicyNever;
    else if (equalIgnoringCase(policy, "always"))
        m_referrerPolicy = ReferrerPolicyAlways;
    else if (equalIgnoringCase(policy, "origin"))
        m_referrerPolicy = ReferrerPolicyOrigin;
}

MouseEventWithHitTestResults Document::prepareMouseEvent(const HitTestRequest& request, const LayoutPoint& documentPoint, const PlatformMouseEvent& event)
{
    ASSERT(!renderer() || renderer()->isRenderView());

    if (!renderer())
        return MouseEventWithHitTestResults(event, HitTestResult(LayoutPoint()));

    HitTestResult result(documentPoint);
    renderView()->hitTest(request, result);

    if (!request.readOnly())
        updateHoverActiveState(request, result.innerElement(), &event);

    return MouseEventWithHitTestResults(event, result);
}

// DOM Section 1.1.1
bool Document::childTypeAllowed(NodeType type) const
{
    switch (type) {
    case ATTRIBUTE_NODE:
    case CDATA_SECTION_NODE:
    case DOCUMENT_FRAGMENT_NODE:
    case DOCUMENT_NODE:
    case ENTITY_NODE:
    case ENTITY_REFERENCE_NODE:
    case NOTATION_NODE:
    case TEXT_NODE:
    case XPATH_NAMESPACE_NODE:
        return false;
    case COMMENT_NODE:
    case PROCESSING_INSTRUCTION_NODE:
        return true;
    case DOCUMENT_TYPE_NODE:
    case ELEMENT_NODE:
        // Documents may contain no more than one of each of these.
        // (One Element and one DocumentType.)
        for (Node* c = firstChild(); c; c = c->nextSibling())
            if (c->nodeType() == type)
                return false;
        return true;
    }
    return false;
}

bool Document::canReplaceChild(Node* newChild, Node* oldChild)
{
    if (!oldChild)
        // ContainerNode::replaceChild will raise a NOT_FOUND_ERR.
        return true;

    if (oldChild->nodeType() == newChild->nodeType())
        return true;

    int numDoctypes = 0;
    int numElements = 0;

    // First, check how many doctypes and elements we have, not counting
    // the child we're about to remove.
    for (Node* c = firstChild(); c; c = c->nextSibling()) {
        if (c == oldChild)
            continue;
        
        switch (c->nodeType()) {
        case DOCUMENT_TYPE_NODE:
            numDoctypes++;
            break;
        case ELEMENT_NODE:
            numElements++;
            break;
        default:
            break;
        }
    }
    
    // Then, see how many doctypes and elements might be added by the new child.
    if (newChild->nodeType() == DOCUMENT_FRAGMENT_NODE) {
        for (Node* c = newChild->firstChild(); c; c = c->nextSibling()) {
            switch (c->nodeType()) {
            case ATTRIBUTE_NODE:
            case CDATA_SECTION_NODE: