static void clearSelectionIfNeeded(Frame* oldFocusedFrame, Frame* newFocusedFrame, Node* newFocusedNode)
{
    if (!oldFocusedFrame || !newFocusedFrame)
        return;
        
    if (oldFocusedFrame->document() != newFocusedFrame->document())
        return;
    
    SelectionController* s = oldFocusedFrame->selection();
    if (s->isNone())
        return;

    bool caretBrowsing = oldFocusedFrame->settings()->caretBrowsingEnabled();
    if (caretBrowsing)
        return;

    Node* selectionStartNode = s->selection().start().node();
    if (selectionStartNode == newFocusedNode || selectionStartNode->isDescendantOf(newFocusedNode) || selectionStartNode->shadowAncestorNode() == newFocusedNode)
        return;
        
    if (Node* mousePressNode = newFocusedFrame->eventHandler()->mousePressNode())
        if (mousePressNode->renderer() && !mousePressNode->canStartSelection())
            if (Node* root = s->rootEditableElement())
                if (Node* shadowAncestorNode = root->shadowAncestorNode())
                    // Don't do this for textareas and text fields, when they lose focus their selections should be cleared
                    // and then restored when they regain focus, to match other browsers.
                    if (!shadowAncestorNode->hasTagName(inputTag) && !shadowAncestorNode->hasTagName(textareaTag))
                        return;
    
    s->clear();
}
bool DOMSelection::containsNode(const Node* n, bool allowPartial) const
{
    if (!m_frame)
        return false;

    SelectionController* selection = m_frame->selection();

    if (!n || selection->isNone())
        return false;

    Node* parentNode = n->parentNode();
    unsigned nodeIndex = n->nodeIndex();
    RefPtr<Range> selectedRange = selection->selection().toNormalizedRange();

    if (!parentNode)
        return false;

    ExceptionCode ec = 0;
    bool nodeFullySelected = Range::compareBoundaryPoints(parentNode, nodeIndex, selectedRange->startContainer(ec), selectedRange->startOffset(ec)) >= 0
        && Range::compareBoundaryPoints(parentNode, nodeIndex + 1, selectedRange->endContainer(ec), selectedRange->endOffset(ec)) <= 0;
    ASSERT(!ec);
    if (nodeFullySelected)
        return true;

    bool nodeFullyUnselected = Range::compareBoundaryPoints(parentNode, nodeIndex, selectedRange->endContainer(ec), selectedRange->endOffset(ec)) > 0
        || Range::compareBoundaryPoints(parentNode, nodeIndex + 1, selectedRange->startContainer(ec), selectedRange->startOffset(ec)) < 0;
    ASSERT(!ec);
    if (nodeFullyUnselected)
        return false;

    return allowPartial || n->isTextNode();
}
String DOMSelection::type() const
{
    if (!m_frame)
        return String();

    SelectionController* selection = m_frame->selection();

    // This is a WebKit DOM extension, incompatible with an IE extension
    // IE has this same attribute, but returns "none", "text" and "control"
    // http://msdn.microsoft.com/en-us/library/ms534692(VS.85).aspx
    if (selection->isNone())
        return "None";
    if (selection->isCaret())
        return "Caret";
    return "Range";
}
void DOMSelection::deleteFromDocument()
{
    if (!m_frame)
        return;

    SelectionController* selection = m_frame->selection();

    if (selection->isNone())
        return;

    if (isCollapsed())
        selection->modify(SelectionController::EXTEND, SelectionController::BACKWARD, CharacterGranularity);

    RefPtr<Range> selectedRange = selection->selection().toNormalizedRange();

    ExceptionCode ec = 0;
    selectedRange->deleteContents(ec);
    ASSERT(!ec);

    setBaseAndExtent(selectedRange->startContainer(ec), selectedRange->startOffset(ec), selectedRange->startContainer(ec), selectedRange->startOffset(ec), ec);
    ASSERT(!ec);
}
void DOMSelection::addRange(Range* r)
{
    if (!m_frame)
        return;
    if (!r)
        return;

    SelectionController* selection = m_frame->selection();

    if (selection->isNone()) {
        selection->setSelection(VisibleSelection(r));
        return;
    }

    RefPtr<Range> range = selection->selection().toNormalizedRange();
    ExceptionCode ec = 0;
    if (r->compareBoundaryPoints(Range::START_TO_START, range.get(), ec) == -1) {
        // We don't support discontiguous selection. We don't do anything if r and range don't intersect.
        if (r->compareBoundaryPoints(Range::START_TO_END, range.get(), ec) > -1) {
            if (r->compareBoundaryPoints(Range::END_TO_END, range.get(), ec) == -1)
                // The original range and r intersect.
                selection->setSelection(VisibleSelection(r->startPosition(), range->endPosition(), DOWNSTREAM));
            else
                // r contains the original range.
                selection->setSelection(VisibleSelection(r));
        }
    } else {
        // We don't support discontiguous selection. We don't do anything if r and range don't intersect.
        if (r->compareBoundaryPoints(Range::END_TO_START, range.get(), ec) < 1) {
            if (r->compareBoundaryPoints(Range::END_TO_END, range.get(), ec) == -1)
                // The original range contains r.
                selection->setSelection(VisibleSelection(range.get()));
            else
                // The original range and r intersect.
                selection->setSelection(VisibleSelection(range->startPosition(), r->endPosition(), DOWNSTREAM));
        }
    }
}
static void clearSelectionIfNeeded(Frame* oldFocusedFrame, Frame* newFocusedFrame, Node* newFocusedNode)
{
    if (!oldFocusedFrame || !newFocusedFrame)
        return;
        
    if (oldFocusedFrame->document() != newFocusedFrame->document())
        return;
    
    SelectionController* s = oldFocusedFrame->selection();
    if (s->isNone())
        return;

    bool caretBrowsing = oldFocusedFrame->settings()->caretBrowsingEnabled();
    if (caretBrowsing)
        return;

    Node* selectionStartNode = s->selection().start().deprecatedNode();
    if (selectionStartNode == newFocusedNode || selectionStartNode->isDescendantOf(newFocusedNode) || selectionStartNode->shadowAncestorNode() == newFocusedNode)
        return;
        
    if (Node* mousePressNode = newFocusedFrame->eventHandler()->mousePressNode()) {
        if (mousePressNode->renderer() && !mousePressNode->canStartSelection()) {
            // Don't clear the selection for contentEditable elements, but do clear it for input and textarea. See bug 38696.
            Node * root = s->rootEditableElement();
            if (!root)
                return;

            if (Node* shadowAncestorNode = root->shadowAncestorNode()) {
                if (!shadowAncestorNode->hasTagName(inputTag) && !shadowAncestorNode->hasTagName(textareaTag))
                    return;
            }
        }
    }
    
    s->clear();
}