void InsertParagraphSeparatorCommand::doApply()
{
    if (!endingSelection().isNonOrphanedCaretOrRange())
        return;

    Position insertionPosition = endingSelection().start();

    EAffinity affinity = endingSelection().affinity();

    // Delete the current selection.
    if (endingSelection().isRange()) {
        calculateStyleBeforeInsertion(insertionPosition);
        deleteSelection(false, true);
        insertionPosition = endingSelection().start();
        affinity = endingSelection().affinity();
    }

    // FIXME: The parentAnchoredEquivalent conversion needs to be moved into enclosingBlock.
    RefPtr<Element> startBlock = enclosingBlock(insertionPosition.parentAnchoredEquivalent().containerNode());
    Position canonicalPos = VisiblePosition(insertionPosition).deepEquivalent();
    if (!startBlock
        || !startBlock->nonShadowBoundaryParentNode()
        // FIXME: If the node is hidden, we don't have a canonical position so we will do the wrong thing for tables and <hr>. https://bugs.webkit.org/show_bug.cgi?id=40342
        || (!canonicalPos.isNull() && isRenderedTableElement(canonicalPos.deprecatedNode()))) {
        applyCommandToComposite(InsertLineBreakCommand::create(document()));
        return;
    }

    // Use the leftmost candidate.
    insertionPosition = insertionPosition.upstream();
    if (!insertionPosition.isCandidate())
        insertionPosition = insertionPosition.downstream();

    // Adjust the insertion position after the delete
    insertionPosition = positionAvoidingSpecialElementBoundary(insertionPosition);
    VisiblePosition visiblePos(insertionPosition, affinity);
    calculateStyleBeforeInsertion(insertionPosition);

    //---------------------------------------------------------------------
    // Handle special case of typing return on an empty list item
    if (breakOutOfEmptyListItem())
        return;

    //---------------------------------------------------------------------
    // Prepare for more general cases.

    bool isFirstInBlock = isStartOfBlock(visiblePos);
    bool isLastInBlock = isEndOfBlock(visiblePos);
    bool nestNewBlock = false;

    // Create block to be inserted.
    RefPtr<Element> blockToInsert = nullptr;
    if (startBlock->isRootEditableElement()) {
        blockToInsert = createDefaultParagraphElement(document());
        nestNewBlock = true;
    } else if (shouldUseDefaultParagraphElement(startBlock.get())) {
        blockToInsert = createDefaultParagraphElement(document());
    } else {
        blockToInsert = startBlock->cloneElementWithoutChildren();
    }

    //---------------------------------------------------------------------
    // Handle case when position is in the last visible position in its block,
    // including when the block is empty.
    if (isLastInBlock) {
        if (nestNewBlock) {
            if (isFirstInBlock && !lineBreakExistsAtVisiblePosition(visiblePos)) {
                // The block is empty.  Create an empty block to
                // represent the paragraph that we're leaving.
                RefPtr<HTMLElement> extraBlock = createDefaultParagraphElement(document());
                appendNode(extraBlock, startBlock);
            }
            appendNode(blockToInsert, startBlock);
        } else {
            // Most of the time we want to stay at the nesting level of the startBlock (e.g., when nesting within lists). However,
            // for div nodes, this can result in nested div tags that are hard to break out of.
            Element* siblingElement = startBlock.get();
            insertNodeAfter(blockToInsert, siblingElement);
        }

        // Recreate the same structure in the new paragraph.

        Vector<RefPtr<Element> > ancestors;
        getAncestorsInsideBlock(positionOutsideTabSpan(insertionPosition).deprecatedNode(), startBlock.get(), ancestors);
        RefPtr<Element> parent = cloneHierarchyUnderNewBlock(ancestors, blockToInsert);

        setEndingSelection(VisibleSelection(firstPositionInNode(parent.get()), DOWNSTREAM, endingSelection().isDirectional()));
        return;
    }


    //---------------------------------------------------------------------
    // Handle case when position is in the first visible position in its block, and
    // similar case where previous position is in another, presumeably nested, block.
    if (isFirstInBlock || !inSameBlock(visiblePos, visiblePos.previous())) {
        Node* refNode = 0;
        insertionPosition = positionOutsideTabSpan(insertionPosition);

        if (isFirstInBlock && !nestNewBlock) {
            refNode = startBlock.get();
        } else if (isFirstInBlock && nestNewBlock) {
            // startBlock should always have children, otherwise isLastInBlock would be true and it's handled above.
            ASSERT(startBlock->hasChildren());
            refNode = startBlock->firstChild();
        }
        else if (insertionPosition.deprecatedNode() == startBlock && nestNewBlock) {
            refNode = NodeTraversal::childAt(*startBlock, insertionPosition.deprecatedEditingOffset());
            ASSERT(refNode); // must be true or we'd be in the end of block case
        } else
            refNode = insertionPosition.deprecatedNode();

        // find ending selection position easily before inserting the paragraph
        insertionPosition = insertionPosition.downstream();

        if (refNode)
            insertNodeBefore(blockToInsert, refNode);

        // Recreate the same structure in the new paragraph.

        Vector<RefPtr<Element> > ancestors;
        getAncestorsInsideBlock(positionAvoidingSpecialElementBoundary(positionOutsideTabSpan(insertionPosition)).deprecatedNode(), startBlock.get(), ancestors);

        // In this case, we need to set the new ending selection.
        setEndingSelection(VisibleSelection(insertionPosition, DOWNSTREAM, endingSelection().isDirectional()));
        return;
    }

    //---------------------------------------------------------------------
    // Handle the (more complicated) general case,

    // Move downstream. Typing style code will take care of carrying along the
    // style of the upstream position.
    insertionPosition = insertionPosition.downstream();

    // At this point, the insertionPosition's node could be a container, and we want to make sure we include
    // all of the correct nodes when building the ancestor list.  So this needs to be the deepest representation of the position
    // before we walk the DOM tree.
    insertionPosition = positionOutsideTabSpan(VisiblePosition(insertionPosition).deepEquivalent());

    // If the returned position lies either at the end or at the start of an element that is ignored by editing
    // we should move to its upstream or downstream position.
    if (editingIgnoresContent(insertionPosition.deprecatedNode())) {
        if (insertionPosition.atLastEditingPositionForNode())
            insertionPosition = insertionPosition.downstream();
        else if (insertionPosition.atFirstEditingPositionForNode())
            insertionPosition = insertionPosition.upstream();
    }

    // Make sure we do not cause a rendered space to become unrendered.
    // FIXME: We need the affinity for pos, but pos.downstream() does not give it
    Position leadingWhitespace = leadingWhitespacePosition(insertionPosition, VP_DEFAULT_AFFINITY);
    // FIXME: leadingWhitespacePosition is returning the position before preserved newlines for positions
    // after the preserved newline, causing the newline to be turned into a nbsp.
    if (leadingWhitespace.isNotNull() && leadingWhitespace.deprecatedNode()->isTextNode()) {
        Text* textNode = toText(leadingWhitespace.deprecatedNode());
        ASSERT(!textNode->renderer() || textNode->renderer()->style()->collapseWhiteSpace());
        replaceTextInNodePreservingMarkers(textNode, leadingWhitespace.deprecatedEditingOffset(), 1, nonBreakingSpaceString());
    }

    // Split at pos if in the middle of a text node.
    Position positionAfterSplit;
    if (insertionPosition.anchorType() == Position::PositionIsOffsetInAnchor && insertionPosition.containerNode()->isTextNode()) {
        RefPtr<Text> textNode = toText(insertionPosition.containerNode());
        bool atEnd = static_cast<unsigned>(insertionPosition.offsetInContainerNode()) >= textNode->length();
        if (insertionPosition.deprecatedEditingOffset() > 0 && !atEnd) {
            splitTextNode(textNode, insertionPosition.offsetInContainerNode());
            positionAfterSplit = firstPositionInNode(textNode.get());
            insertionPosition.moveToPosition(textNode->previousSibling(), insertionPosition.offsetInContainerNode());
            visiblePos = VisiblePosition(insertionPosition);
        }
    }

    // If we got detached due to mutation events, just bail out.
    if (!startBlock->parentNode())
        return;

    // Put the added block in the tree.
    if (nestNewBlock) {
        appendNode(blockToInsert.get(), startBlock);
    } else {
        insertNodeAfter(blockToInsert.get(), startBlock);
    }

    document().updateLayoutIgnorePendingStylesheets();

    // Move the start node and the siblings of the start node.
    if (VisiblePosition(insertionPosition) != VisiblePosition(positionBeforeNode(blockToInsert.get()))) {
        Node* n;
        if (insertionPosition.containerNode() == startBlock)
            n = insertionPosition.computeNodeAfterPosition();
        else {
            Node* splitTo = insertionPosition.containerNode();
            if (splitTo->isTextNode() && insertionPosition.offsetInContainerNode() >= caretMaxOffset(splitTo))
                splitTo = NodeTraversal::next(*splitTo, startBlock.get());
            ASSERT(splitTo);
            splitTreeToNode(splitTo, startBlock.get());

            for (n = startBlock->firstChild(); n; n = n->nextSibling()) {
                VisiblePosition beforeNodePosition(positionBeforeNode(n));
                if (!beforeNodePosition.isNull() && comparePositions(VisiblePosition(insertionPosition), beforeNodePosition) <= 0)
                    break;
            }
        }

        moveRemainingSiblingsToNewParent(n, blockToInsert.get(), blockToInsert);
    }

    // Handle whitespace that occurs after the split
    if (positionAfterSplit.isNotNull()) {
        document().updateLayoutIgnorePendingStylesheets();
        if (!positionAfterSplit.isRenderedCharacter()) {
            // Clear out all whitespace and insert one non-breaking space
            ASSERT(!positionAfterSplit.containerNode()->renderer() || positionAfterSplit.containerNode()->renderer()->style()->collapseWhiteSpace());
            deleteInsignificantTextDownstream(positionAfterSplit);
            if (positionAfterSplit.deprecatedNode()->isTextNode())
                insertTextIntoNode(toText(positionAfterSplit.containerNode()), 0, nonBreakingSpaceString());
        }
    }

    setEndingSelection(VisibleSelection(firstPositionInNode(blockToInsert.get()), DOWNSTREAM, endingSelection().isDirectional()));
}
void InsertTextCommand::doApply()
{
    ASSERT(m_text.find('\n') == kNotFound);

    if (!endingSelection().isNonOrphanedCaretOrRange())
        return;

    // Delete the current selection.
    // FIXME: This delete operation blows away the typing style.
    if (endingSelection().isRange()) {
        if (performTrivialReplace(m_text, m_selectInsertedText))
            return;
        bool endOfSelectionWasAtStartOfBlock = isStartOfBlock(endingSelection().visibleEnd());
        deleteSelection(false, true, false, false);
        // deleteSelection eventually makes a new endingSelection out of a Position. If that Position doesn't have
        // a renderer (e.g. it is on a <frameset> in the DOM), the VisibleSelection cannot be canonicalized to
        // anything other than NoSelection. The rest of this function requires a real endingSelection, so bail out.
        if (endingSelection().isNone())
            return;
        if (endOfSelectionWasAtStartOfBlock) {
            if (EditingStyle* typingStyle = document().frame()->selection().typingStyle())
                typingStyle->removeBlockProperties();
        }
    } else if (document().frame()->editor().isOverwriteModeEnabled()) {
        if (performOverwrite(m_text, m_selectInsertedText))
            return;
    }

    Position startPosition(endingSelection().start());

    Position placeholder;
    // We want to remove preserved newlines and brs that will collapse (and thus become unnecessary) when content
    // is inserted just before them.
    // FIXME: We shouldn't really have to do this, but removing placeholders is a workaround for 9661.
    // If the caret is just before a placeholder, downstream will normalize the caret to it.
    Position downstream(startPosition.downstream());
    if (lineBreakExistsAtPosition(downstream)) {
        // FIXME: This doesn't handle placeholders at the end of anonymous blocks.
        VisiblePosition caret(startPosition);
        if (isEndOfBlock(caret) && isStartOfParagraph(caret))
            placeholder = downstream;
        // Don't remove the placeholder yet, otherwise the block we're inserting into would collapse before
        // we get a chance to insert into it.  We check for a placeholder now, though, because doing so requires
        // the creation of a VisiblePosition, and if we did that post-insertion it would force a layout.
    }

    // Insert the character at the leftmost candidate.
    startPosition = startPosition.upstream();

    // It is possible for the node that contains startPosition to contain only unrendered whitespace,
    // and so deleteInsignificantText could remove it.  Save the position before the node in case that happens.
    ASSERT(startPosition.containerNode());
    Position positionBeforeStartNode(positionInParentBeforeNode(*startPosition.containerNode()));
    deleteInsignificantText(startPosition, startPosition.downstream());
    if (!startPosition.inDocument())
        startPosition = positionBeforeStartNode;
    if (!startPosition.isCandidate())
        startPosition = startPosition.downstream();

    startPosition = positionAvoidingSpecialElementBoundary(startPosition);

    Position endPosition;

    if (m_text == "\t") {
        endPosition = insertTab(startPosition);
        startPosition = endPosition.previous();
        if (placeholder.isNotNull())
            removePlaceholderAt(placeholder);
    } else {
        // Make sure the document is set up to receive m_text
        startPosition = positionInsideTextNode(startPosition);
        ASSERT(startPosition.anchorType() == Position::PositionIsOffsetInAnchor);
        ASSERT(startPosition.containerNode());
        ASSERT(startPosition.containerNode()->isTextNode());
        if (placeholder.isNotNull())
            removePlaceholderAt(placeholder);
        RefPtrWillBeRawPtr<Text> textNode = startPosition.containerText();
        const unsigned offset = startPosition.offsetInContainerNode();

        insertTextIntoNode(textNode, offset, m_text);
        endPosition = Position(textNode, offset + m_text.length());

        if (m_rebalanceType == RebalanceLeadingAndTrailingWhitespaces) {
            // The insertion may require adjusting adjacent whitespace, if it is present.
            rebalanceWhitespaceAt(endPosition);
            // Rebalancing on both sides isn't necessary if we've inserted only spaces.
            if (!shouldRebalanceLeadingWhitespaceFor(m_text))
                rebalanceWhitespaceAt(startPosition);
        } else {
            ASSERT(m_rebalanceType == RebalanceAllWhitespaces);
            if (canRebalance(startPosition) && canRebalance(endPosition))
                rebalanceWhitespaceOnTextSubstring(textNode, startPosition.offsetInContainerNode(), endPosition.offsetInContainerNode());
        }
    }

    setEndingSelectionWithoutValidation(startPosition, endPosition);

    // Handle the case where there is a typing style.
    if (RefPtrWillBeRawPtr<EditingStyle> typingStyle = document().frame()->selection().typingStyle()) {
        typingStyle->prepareToApplyAt(endPosition, EditingStyle::PreserveWritingDirection);
        if (!typingStyle->isEmpty())
            applyStyle(typingStyle.get());
    }

    if (!m_selectInsertedText)
        setEndingSelection(VisibleSelection(endingSelection().end(), endingSelection().affinity(), endingSelection().isDirectional()));
}