WebCore/editing/CompositeEditCommand.cpp
changeset 0 4f2f89ce4247
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WebCore/editing/CompositeEditCommand.cpp	Fri Sep 17 09:02:29 2010 +0300
@@ -0,0 +1,1204 @@
+/*
+ * Copyright (C) 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "CompositeEditCommand.h"
+
+#include "AppendNodeCommand.h"
+#include "ApplyStyleCommand.h"
+#include "CSSComputedStyleDeclaration.h"
+#include "CSSMutableStyleDeclaration.h"
+#include "CharacterNames.h"
+#include "DeleteFromTextNodeCommand.h"
+#include "DeleteSelectionCommand.h"
+#include "Document.h"
+#include "DocumentFragment.h"
+#include "EditorInsertAction.h"
+#include "HTMLElement.h"
+#include "HTMLNames.h"
+#include "InlineTextBox.h"
+#include "InsertIntoTextNodeCommand.h"
+#include "InsertLineBreakCommand.h"
+#include "InsertNodeBeforeCommand.h"
+#include "InsertParagraphSeparatorCommand.h"
+#include "InsertTextCommand.h"
+#include "JoinTextNodesCommand.h"
+#include "MergeIdenticalElementsCommand.h"
+#include "Range.h"
+#include "RemoveCSSPropertyCommand.h"
+#include "RemoveNodeCommand.h"
+#include "RemoveNodePreservingChildrenCommand.h"
+#include "ReplaceNodeWithSpanCommand.h"
+#include "ReplaceSelectionCommand.h"
+#include "RenderBlock.h"
+#include "RenderText.h"
+#include "SetNodeAttributeCommand.h"
+#include "SplitElementCommand.h"
+#include "SplitTextNodeCommand.h"
+#include "SplitTextNodeContainingElementCommand.h"
+#include "Text.h"
+#include "TextIterator.h"
+#include "WrapContentsInDummySpanCommand.h"
+#include "htmlediting.h"
+#include "markup.h"
+#include "visible_units.h"
+
+using namespace std;
+
+namespace WebCore {
+
+using namespace HTMLNames;
+
+CompositeEditCommand::CompositeEditCommand(Document *document)
+    : EditCommand(document)
+{
+}
+
+void CompositeEditCommand::doUnapply()
+{
+    size_t size = m_commands.size();
+    for (size_t i = size; i != 0; --i)
+        m_commands[i - 1]->unapply();
+}
+
+void CompositeEditCommand::doReapply()
+{
+    size_t size = m_commands.size();
+    for (size_t i = 0; i != size; ++i)
+        m_commands[i]->reapply();
+}
+
+//
+// sugary-sweet convenience functions to help create and apply edit commands in composite commands
+//
+void CompositeEditCommand::applyCommandToComposite(PassRefPtr<EditCommand> cmd)
+{
+    cmd->setParent(this);
+    cmd->apply();
+    m_commands.append(cmd);
+}
+
+void CompositeEditCommand::applyStyle(CSSStyleDeclaration* style, EditAction editingAction)
+{
+    applyCommandToComposite(ApplyStyleCommand::create(document(), style, editingAction));
+}
+
+void CompositeEditCommand::applyStyle(CSSStyleDeclaration* style, const Position& start, const Position& end, EditAction editingAction)
+{
+    applyCommandToComposite(ApplyStyleCommand::create(document(), style, start, end, editingAction));
+}
+
+void CompositeEditCommand::applyStyledElement(PassRefPtr<Element> element)
+{
+    applyCommandToComposite(ApplyStyleCommand::create(element, false));
+}
+
+void CompositeEditCommand::removeStyledElement(PassRefPtr<Element> element)
+{
+    applyCommandToComposite(ApplyStyleCommand::create(element, true));
+}
+
+void CompositeEditCommand::insertParagraphSeparator(bool useDefaultParagraphElement)
+{
+    applyCommandToComposite(InsertParagraphSeparatorCommand::create(document(), useDefaultParagraphElement));
+}
+
+void CompositeEditCommand::insertLineBreak()
+{
+    applyCommandToComposite(InsertLineBreakCommand::create(document()));
+}
+
+void CompositeEditCommand::insertNodeBefore(PassRefPtr<Node> insertChild, PassRefPtr<Node> refChild)
+{
+    ASSERT(!refChild->hasTagName(bodyTag));
+    applyCommandToComposite(InsertNodeBeforeCommand::create(insertChild, refChild));
+}
+
+void CompositeEditCommand::insertNodeAfter(PassRefPtr<Node> insertChild, PassRefPtr<Node> refChild)
+{
+    ASSERT(insertChild);
+    ASSERT(refChild);
+    ASSERT(!refChild->hasTagName(bodyTag));
+    Element* parent = refChild->parentElement();
+    ASSERT(parent);
+    if (parent->lastChild() == refChild)
+        appendNode(insertChild, parent);
+    else {
+        ASSERT(refChild->nextSibling());
+        insertNodeBefore(insertChild, refChild->nextSibling());
+    }
+}
+
+void CompositeEditCommand::insertNodeAt(PassRefPtr<Node> insertChild, const Position& editingPosition)
+{
+    ASSERT(isEditablePosition(editingPosition));
+    // For editing positions like [table, 0], insert before the table,
+    // likewise for replaced elements, brs, etc.
+    Position p = rangeCompliantEquivalent(editingPosition);
+    Node* refChild = p.node();
+    int offset = p.deprecatedEditingOffset();
+    
+    if (canHaveChildrenForEditing(refChild)) {
+        Node* child = refChild->firstChild();
+        for (int i = 0; child && i < offset; i++)
+            child = child->nextSibling();
+        if (child)
+            insertNodeBefore(insertChild, child);
+        else
+            appendNode(insertChild, static_cast<Element*>(refChild));
+    } else if (caretMinOffset(refChild) >= offset)
+        insertNodeBefore(insertChild, refChild);
+    else if (refChild->isTextNode() && caretMaxOffset(refChild) > offset) {
+        splitTextNode(static_cast<Text *>(refChild), offset);
+
+        // Mutation events (bug 22634) from the text node insertion may have removed the refChild
+        if (!refChild->inDocument())
+            return;
+        insertNodeBefore(insertChild, refChild);
+    } else
+        insertNodeAfter(insertChild, refChild);
+}
+
+void CompositeEditCommand::appendNode(PassRefPtr<Node> node, PassRefPtr<Element> parent)
+{
+    ASSERT(canHaveChildrenForEditing(parent.get()));
+    applyCommandToComposite(AppendNodeCommand::create(parent, node));
+}
+
+void CompositeEditCommand::removeChildrenInRange(PassRefPtr<Node> node, unsigned from, unsigned to)
+{
+    Vector<RefPtr<Node> > children;
+    Node* child = node->childNode(from);
+    for (unsigned i = from; child && i < to; i++, child = child->nextSibling())
+        children.append(child);
+
+    size_t size = children.size();
+    for (size_t i = 0; i < size; ++i)
+        removeNode(children[i].release());
+}
+
+void CompositeEditCommand::removeNode(PassRefPtr<Node> node)
+{
+    applyCommandToComposite(RemoveNodeCommand::create(node));
+}
+
+void CompositeEditCommand::removeNodePreservingChildren(PassRefPtr<Node> node)
+{
+    applyCommandToComposite(RemoveNodePreservingChildrenCommand::create(node));
+}
+
+void CompositeEditCommand::removeNodeAndPruneAncestors(PassRefPtr<Node> node)
+{
+    RefPtr<Node> parent = node->parentNode();
+    removeNode(node);
+    prune(parent.release());
+}
+
+HTMLElement* CompositeEditCommand::replaceNodeWithSpanPreservingChildrenAndAttributes(PassRefPtr<Node> node)
+{
+    // It would also be possible to implement all of ReplaceNodeWithSpanCommand
+    // as a series of existing smaller edit commands.  Someone who wanted to
+    // reduce the number of edit commands could do so here.
+    RefPtr<ReplaceNodeWithSpanCommand> command = ReplaceNodeWithSpanCommand::create(node);
+    applyCommandToComposite(command);
+    // Returning a raw pointer here is OK because the command is retained by
+    // applyCommandToComposite (thus retaining the span), and the span is also
+    // in the DOM tree, and thus alive whie it has a parent.
+    ASSERT(command->spanElement()->inDocument());
+    return command->spanElement();
+}
+
+static bool hasARenderedDescendant(Node* node)
+{
+    Node* n = node->firstChild();
+    while (n) {
+        if (n->renderer())
+            return true;
+        n = n->traverseNextNode(node);
+    }
+    return false;
+}
+
+void CompositeEditCommand::prune(PassRefPtr<Node> node)
+{
+    while (node) {
+        // If you change this rule you may have to add an updateLayout() here.
+        RenderObject* renderer = node->renderer();
+        if (renderer && (!renderer->canHaveChildren() || hasARenderedDescendant(node.get()) || node->rootEditableElement() == node))
+            return;
+            
+        RefPtr<Node> next = node->parentNode();
+        removeNode(node);
+        node = next;
+    }
+}
+
+void CompositeEditCommand::splitTextNode(PassRefPtr<Text> node, unsigned offset)
+{
+    applyCommandToComposite(SplitTextNodeCommand::create(node, offset));
+}
+
+void CompositeEditCommand::splitElement(PassRefPtr<Element> element, PassRefPtr<Node> atChild)
+{
+    applyCommandToComposite(SplitElementCommand::create(element, atChild));
+}
+
+void CompositeEditCommand::mergeIdenticalElements(PassRefPtr<Element> prpFirst, PassRefPtr<Element> prpSecond)
+{
+    RefPtr<Element> first = prpFirst;
+    RefPtr<Element> second = prpSecond;
+    ASSERT(!first->isDescendantOf(second.get()) && second != first);
+    if (first->nextSibling() != second) {
+        removeNode(second);
+        insertNodeAfter(second, first);
+    }
+    applyCommandToComposite(MergeIdenticalElementsCommand::create(first, second));
+}
+
+void CompositeEditCommand::wrapContentsInDummySpan(PassRefPtr<Element> element)
+{
+    applyCommandToComposite(WrapContentsInDummySpanCommand::create(element));
+}
+
+void CompositeEditCommand::splitTextNodeContainingElement(PassRefPtr<Text> text, unsigned offset)
+{
+    applyCommandToComposite(SplitTextNodeContainingElementCommand::create(text, offset));
+}
+
+void CompositeEditCommand::joinTextNodes(PassRefPtr<Text> text1, PassRefPtr<Text> text2)
+{
+    applyCommandToComposite(JoinTextNodesCommand::create(text1, text2));
+}
+
+void CompositeEditCommand::inputText(const String& text, bool selectInsertedText)
+{
+    int offset = 0;
+    int length = text.length();
+    RefPtr<Range> startRange = Range::create(document(), Position(document()->documentElement(), 0), endingSelection().start());
+    int startIndex = TextIterator::rangeLength(startRange.get());
+    int newline;
+    do {
+        newline = text.find('\n', offset);
+        if (newline != offset) {
+            RefPtr<InsertTextCommand> command = InsertTextCommand::create(document());
+            applyCommandToComposite(command);
+            int substringLength = newline == -1 ? length - offset : newline - offset;
+            command->input(text.substring(offset, substringLength), false);
+        }
+        if (newline != -1)
+            insertLineBreak();
+            
+        offset = newline + 1;
+    } while (newline != -1 && offset != length);
+    
+    if (selectInsertedText) {
+        RefPtr<Range> selectedRange = TextIterator::rangeFromLocationAndLength(document()->documentElement(), startIndex, length);
+        setEndingSelection(VisibleSelection(selectedRange.get()));
+    }
+}
+
+void CompositeEditCommand::insertTextIntoNode(PassRefPtr<Text> node, unsigned offset, const String& text)
+{
+    applyCommandToComposite(InsertIntoTextNodeCommand::create(node, offset, text));
+}
+
+void CompositeEditCommand::deleteTextFromNode(PassRefPtr<Text> node, unsigned offset, unsigned count)
+{
+    applyCommandToComposite(DeleteFromTextNodeCommand::create(node, offset, count));
+}
+
+void CompositeEditCommand::replaceTextInNode(PassRefPtr<Text> node, unsigned offset, unsigned count, const String& replacementText)
+{
+    applyCommandToComposite(DeleteFromTextNodeCommand::create(node.get(), offset, count));
+    applyCommandToComposite(InsertIntoTextNodeCommand::create(node, offset, replacementText));
+}
+
+Position CompositeEditCommand::positionOutsideTabSpan(const Position& pos)
+{
+    if (!isTabSpanTextNode(pos.node()))
+        return pos;
+    
+    Node* tabSpan = tabSpanNode(pos.node());
+    
+    if (pos.deprecatedEditingOffset() <= caretMinOffset(pos.node()))
+        return positionInParentBeforeNode(tabSpan);
+        
+    if (pos.deprecatedEditingOffset() >= caretMaxOffset(pos.node()))
+        return positionInParentAfterNode(tabSpan);
+
+    splitTextNodeContainingElement(static_cast<Text *>(pos.node()), pos.deprecatedEditingOffset());
+    return positionInParentBeforeNode(tabSpan);
+}
+
+void CompositeEditCommand::insertNodeAtTabSpanPosition(PassRefPtr<Node> node, const Position& pos)
+{
+    // insert node before, after, or at split of tab span
+    insertNodeAt(node, positionOutsideTabSpan(pos));
+}
+
+void CompositeEditCommand::deleteSelection(bool smartDelete, bool mergeBlocksAfterDelete, bool replace, bool expandForSpecialElements)
+{
+    if (endingSelection().isRange())
+        applyCommandToComposite(DeleteSelectionCommand::create(document(), smartDelete, mergeBlocksAfterDelete, replace, expandForSpecialElements));
+}
+
+void CompositeEditCommand::deleteSelection(const VisibleSelection &selection, bool smartDelete, bool mergeBlocksAfterDelete, bool replace, bool expandForSpecialElements)
+{
+    if (selection.isRange())
+        applyCommandToComposite(DeleteSelectionCommand::create(selection, smartDelete, mergeBlocksAfterDelete, replace, expandForSpecialElements));
+}
+
+void CompositeEditCommand::removeCSSProperty(PassRefPtr<CSSMutableStyleDeclaration> style, CSSPropertyID property)
+{
+    applyCommandToComposite(RemoveCSSPropertyCommand::create(document(), style, property));
+}
+
+void CompositeEditCommand::removeNodeAttribute(PassRefPtr<Element> element, const QualifiedName& attribute)
+{
+    setNodeAttribute(element, attribute, AtomicString());
+}
+
+void CompositeEditCommand::setNodeAttribute(PassRefPtr<Element> element, const QualifiedName& attribute, const AtomicString& value)
+{
+    applyCommandToComposite(SetNodeAttributeCommand::create(element, attribute, value));
+}
+
+static inline bool isWhitespace(UChar c)
+{
+    return c == noBreakSpace || c == ' ' || c == '\n' || c == '\t';
+}
+
+// FIXME: Doesn't go into text nodes that contribute adjacent text (siblings, cousins, etc).
+void CompositeEditCommand::rebalanceWhitespaceAt(const Position& position)
+{
+    Node* node = position.node();
+    if (!node || !node->isTextNode())
+        return;
+    Text* textNode = static_cast<Text*>(node);
+    
+    if (textNode->length() == 0)
+        return;
+    RenderObject* renderer = textNode->renderer();
+    if (renderer && !renderer->style()->collapseWhiteSpace())
+        return;
+        
+    String text = textNode->data();
+    ASSERT(!text.isEmpty());
+
+    int offset = position.deprecatedEditingOffset();
+    // If neither text[offset] nor text[offset - 1] are some form of whitespace, do nothing.
+    if (!isWhitespace(text[offset])) {
+        offset--;
+        if (offset < 0 || !isWhitespace(text[offset]))
+            return;
+    }
+    
+    // Set upstream and downstream to define the extent of the whitespace surrounding text[offset].
+    int upstream = offset;
+    while (upstream > 0 && isWhitespace(text[upstream - 1]))
+        upstream--;
+    
+    int downstream = offset;
+    while ((unsigned)downstream + 1 < text.length() && isWhitespace(text[downstream + 1]))
+        downstream++;
+    
+    int length = downstream - upstream + 1;
+    ASSERT(length > 0);
+    
+    VisiblePosition visibleUpstreamPos(Position(position.node(), upstream));
+    VisiblePosition visibleDownstreamPos(Position(position.node(), downstream + 1));
+    
+    String string = text.substring(upstream, length);
+    String rebalancedString = stringWithRebalancedWhitespace(string,
+    // FIXME: Because of the problem mentioned at the top of this function, we must also use nbsps at the start/end of the string because
+    // this function doesn't get all surrounding whitespace, just the whitespace in the current text node.
+                                                             isStartOfParagraph(visibleUpstreamPos) || upstream == 0, 
+                                                             isEndOfParagraph(visibleDownstreamPos) || (unsigned)downstream == text.length() - 1);
+    
+    if (string != rebalancedString)
+        replaceTextInNode(textNode, upstream, length, rebalancedString);
+}
+
+void CompositeEditCommand::prepareWhitespaceAtPositionForSplit(Position& position)
+{
+    Node* node = position.node();
+    if (!node || !node->isTextNode())
+        return;
+    Text* textNode = static_cast<Text*>(node);    
+    
+    if (textNode->length() == 0)
+        return;
+    RenderObject* renderer = textNode->renderer();
+    if (renderer && !renderer->style()->collapseWhiteSpace())
+        return;
+
+    // Delete collapsed whitespace so that inserting nbsps doesn't uncollapse it.
+    Position upstreamPos = position.upstream();
+    deleteInsignificantText(position.upstream(), position.downstream());
+    position = upstreamPos.downstream();
+
+    VisiblePosition visiblePos(position);
+    VisiblePosition previousVisiblePos(visiblePos.previous());
+    Position previous(previousVisiblePos.deepEquivalent());
+    
+    if (isCollapsibleWhitespace(previousVisiblePos.characterAfter()) && previous.node()->isTextNode() && !previous.node()->hasTagName(brTag))
+        replaceTextInNode(static_cast<Text*>(previous.node()), previous.deprecatedEditingOffset(), 1, nonBreakingSpaceString());
+    if (isCollapsibleWhitespace(visiblePos.characterAfter()) && position.node()->isTextNode() && !position.node()->hasTagName(brTag))
+        replaceTextInNode(static_cast<Text*>(position.node()), position.deprecatedEditingOffset(), 1, nonBreakingSpaceString());
+}
+
+void CompositeEditCommand::rebalanceWhitespace()
+{
+    VisibleSelection selection = endingSelection();
+    if (selection.isNone())
+        return;
+        
+    rebalanceWhitespaceAt(selection.start());
+    if (selection.isRange())
+        rebalanceWhitespaceAt(selection.end());
+}
+
+void CompositeEditCommand::deleteInsignificantText(PassRefPtr<Text> textNode, unsigned start, unsigned end)
+{
+    if (!textNode || start >= end)
+        return;
+
+    RenderText* textRenderer = toRenderText(textNode->renderer());
+    if (!textRenderer)
+        return;
+
+    InlineTextBox* box = textRenderer->firstTextBox();
+    if (!box) {
+        // whole text node is empty
+        removeNode(textNode);
+        return;    
+    }
+    
+    unsigned length = textNode->length();
+    if (start >= length || end > length)
+        return;
+
+    unsigned removed = 0;
+    InlineTextBox* prevBox = 0;
+    String str;
+
+    // This loop structure works to process all gaps preceding a box,
+    // and also will look at the gap after the last box.
+    while (prevBox || box) {
+        unsigned gapStart = prevBox ? prevBox->start() + prevBox->len() : 0;
+        if (end < gapStart)
+            // No more chance for any intersections
+            break;
+
+        unsigned gapEnd = box ? box->start() : length;
+        bool indicesIntersect = start <= gapEnd && end >= gapStart;
+        int gapLen = gapEnd - gapStart;
+        if (indicesIntersect && gapLen > 0) {
+            gapStart = max(gapStart, start);
+            gapEnd = min(gapEnd, end);
+            if (str.isNull())
+                str = textNode->data().substring(start, end - start);
+            // remove text in the gap
+            str.remove(gapStart - start - removed, gapLen);
+            removed += gapLen;
+        }
+        
+        prevBox = box;
+        if (box)
+            box = box->nextTextBox();
+    }
+
+    if (!str.isNull()) {
+        // Replace the text between start and end with our pruned version.
+        if (!str.isEmpty())
+            replaceTextInNode(textNode, start, end - start, str);
+        else {
+            // Assert that we are not going to delete all of the text in the node.
+            // If we were, that should have been done above with the call to 
+            // removeNode and return.
+            ASSERT(start > 0 || end - start < textNode->length());
+            deleteTextFromNode(textNode, start, end - start);
+        }
+    }
+}
+
+void CompositeEditCommand::deleteInsignificantText(const Position& start, const Position& end)
+{
+    if (start.isNull() || end.isNull())
+        return;
+
+    if (comparePositions(start, end) >= 0)
+        return;
+
+    Node* next;
+    for (Node* node = start.node(); node; node = next) {
+        next = node->traverseNextNode();
+        if (node->isTextNode()) {
+            Text* textNode = static_cast<Text*>(node);
+            int startOffset = node == start.node() ? start.deprecatedEditingOffset() : 0;
+            int endOffset = node == end.node() ? end.deprecatedEditingOffset() : static_cast<int>(textNode->length());
+            deleteInsignificantText(textNode, startOffset, endOffset);
+        }
+        if (node == end.node())
+            break;
+    }
+}
+
+void CompositeEditCommand::deleteInsignificantTextDownstream(const Position& pos)
+{
+    Position end = VisiblePosition(pos, VP_DEFAULT_AFFINITY).next().deepEquivalent().downstream();
+    deleteInsignificantText(pos, end);
+}
+
+PassRefPtr<Node> CompositeEditCommand::appendBlockPlaceholder(PassRefPtr<Element> container)
+{
+    if (!container)
+        return 0;
+    
+    // Should assert isBlockFlow || isInlineFlow when deletion improves. See 4244964.
+    ASSERT(container->renderer());
+
+    RefPtr<Node> placeholder = createBlockPlaceholderElement(document());
+    appendNode(placeholder, container);
+    return placeholder.release();
+}
+
+PassRefPtr<Node> CompositeEditCommand::insertBlockPlaceholder(const Position& pos)
+{
+    if (pos.isNull())
+        return 0;
+
+    // Should assert isBlockFlow || isInlineFlow when deletion improves.  See 4244964.
+    ASSERT(pos.node()->renderer());
+
+    RefPtr<Node> placeholder = createBlockPlaceholderElement(document());
+    insertNodeAt(placeholder, pos);
+    return placeholder.release();
+}
+
+PassRefPtr<Node> CompositeEditCommand::addBlockPlaceholderIfNeeded(Element* container)
+{
+    if (!container)
+        return 0;
+
+    updateLayout();
+
+    RenderObject* renderer = container->renderer();
+    if (!renderer || !renderer->isBlockFlow())
+        return 0;
+    
+    // append the placeholder to make sure it follows
+    // any unrendered blocks
+    RenderBlock* block = toRenderBlock(renderer);
+    if (block->height() == 0 || (block->isListItem() && block->isEmpty()))
+        return appendBlockPlaceholder(container);
+
+    return 0;
+}
+
+// Assumes that the position is at a placeholder and does the removal without much checking.
+void CompositeEditCommand::removePlaceholderAt(const Position& p)
+{
+    ASSERT(lineBreakExistsAtPosition(p));
+    
+    // We are certain that the position is at a line break, but it may be a br or a preserved newline.
+    if (p.anchorNode()->hasTagName(brTag)) {
+        removeNode(p.anchorNode());
+        return;
+    }
+    
+    deleteTextFromNode(static_cast<Text*>(p.anchorNode()), p.offsetInContainerNode(), 1);
+}
+
+PassRefPtr<Node> CompositeEditCommand::insertNewDefaultParagraphElementAt(const Position& position)
+{
+    RefPtr<Element> paragraphElement = createDefaultParagraphElement(document());
+    ExceptionCode ec;
+    paragraphElement->appendChild(createBreakElement(document()), ec);
+    insertNodeAt(paragraphElement, position);
+    return paragraphElement.release();
+}
+
+// If the paragraph is not entirely within it's own block, create one and move the paragraph into 
+// it, and return that block.  Otherwise return 0.
+PassRefPtr<Node> CompositeEditCommand::moveParagraphContentsToNewBlockIfNecessary(const Position& pos)
+{
+    if (pos.isNull())
+        return 0;
+    
+    updateLayout();
+    
+    // It's strange that this function is responsible for verifying that pos has not been invalidated
+    // by an earlier call to this function.  The caller, applyBlockStyle, should do this.
+    VisiblePosition visiblePos(pos, VP_DEFAULT_AFFINITY);
+    VisiblePosition visibleParagraphStart(startOfParagraph(visiblePos));
+    VisiblePosition visibleParagraphEnd = endOfParagraph(visiblePos);
+    VisiblePosition next = visibleParagraphEnd.next();
+    VisiblePosition visibleEnd = next.isNotNull() ? next : visibleParagraphEnd;
+    
+    Position upstreamStart = visibleParagraphStart.deepEquivalent().upstream();
+    Position upstreamEnd = visibleEnd.deepEquivalent().upstream();
+
+    // If there are no VisiblePositions in the same block as pos then 
+    // upstreamStart will be outside the paragraph
+    if (comparePositions(pos, upstreamStart) < 0)
+        return 0;
+
+    // Perform some checks to see if we need to perform work in this function.
+    if (isBlock(upstreamStart.node())) {
+        // If the block is the root editable element, always move content to a new block,
+        // since it is illegal to modify attributes on the root editable element for editing.
+        if (upstreamStart.node() == editableRootForPosition(upstreamStart)) {
+            // If the block is the root editable element and it contains no visible content, create a new
+            // block but don't try and move content into it, since there's nothing for moveParagraphs to move.
+            if (!Position::hasRenderedNonAnonymousDescendantsWithHeight(upstreamStart.node()->renderer()))
+                return insertNewDefaultParagraphElementAt(upstreamStart);
+        } else if (isBlock(upstreamEnd.node())) {
+            if (!upstreamEnd.node()->isDescendantOf(upstreamStart.node())) {
+                // If the paragraph end is a descendant of paragraph start, then we need to run
+                // the rest of this function. If not, we can bail here.
+                return 0;
+            }
+        }
+        else if (enclosingBlock(upstreamEnd.node()) != upstreamStart.node()) {
+            // The visibleEnd.  It must be an ancestor of the paragraph start.
+            // We can bail as we have a full block to work with.
+            ASSERT(upstreamStart.node()->isDescendantOf(enclosingBlock(upstreamEnd.node())));
+            return 0;
+        }
+        else if (isEndOfDocument(visibleEnd)) {
+            // At the end of the document. We can bail here as well.
+            return 0;
+        }
+    }
+
+    RefPtr<Node> newBlock = insertNewDefaultParagraphElementAt(upstreamStart);
+    
+    moveParagraphs(visibleParagraphStart, visibleParagraphEnd, VisiblePosition(Position(newBlock.get(), 0)));
+    
+    return newBlock.release();
+}
+
+void CompositeEditCommand::pushAnchorElementDown(Node* anchorNode)
+{
+    if (!anchorNode)
+        return;
+    
+    ASSERT(anchorNode->isLink());
+    
+    setEndingSelection(VisibleSelection::selectionFromContentsOfNode(anchorNode));
+    applyStyledElement(static_cast<Element*>(anchorNode));
+    // Clones of anchorNode have been pushed down, now remove it.
+    if (anchorNode->inDocument())
+        removeNodePreservingChildren(anchorNode);
+}
+
+// We must push partially selected anchors down before creating or removing
+// links from a selection to create fully selected chunks that can be removed.
+// ApplyStyleCommand doesn't do this for us because styles can be nested.
+// Anchors cannot be nested.
+void CompositeEditCommand::pushPartiallySelectedAnchorElementsDown()
+{
+    VisibleSelection originalSelection = endingSelection();
+    VisiblePosition visibleStart(originalSelection.start());
+    VisiblePosition visibleEnd(originalSelection.end());
+    
+    Node* startAnchor = enclosingAnchorElement(originalSelection.start());
+    VisiblePosition startOfStartAnchor(Position(startAnchor, 0));
+    if (startAnchor && startOfStartAnchor != visibleStart)
+        pushAnchorElementDown(startAnchor);
+
+    Node* endAnchor = enclosingAnchorElement(originalSelection.end());
+    VisiblePosition endOfEndAnchor(Position(endAnchor, 0));
+    if (endAnchor && endOfEndAnchor != visibleEnd)
+        pushAnchorElementDown(endAnchor);
+
+    ASSERT(originalSelection.start().node()->inDocument() && originalSelection.end().node()->inDocument());
+    setEndingSelection(originalSelection);
+}
+
+// Clone the paragraph between start and end under blockElement,
+// preserving the hierarchy up to outerNode. 
+
+void CompositeEditCommand::cloneParagraphUnderNewElement(Position& start, Position& end, Node* outerNode, Element* blockElement)
+{
+    // First we clone the outerNode
+    
+    RefPtr<Node> topNode = outerNode->cloneNode(isTableElement(outerNode));
+    appendNode(topNode, blockElement);
+    RefPtr<Node> lastNode = topNode;
+
+    if (start.node() != outerNode) {
+        Vector<RefPtr<Node> > ancestors;
+        
+        // Insert each node from innerNode to outerNode (excluded) in a list.
+        for (Node* n = start.node(); n && n != outerNode; n = n->parentNode())
+            ancestors.append(n);
+
+        // Clone every node between start.node() and outerBlock.
+
+        for (size_t i = ancestors.size(); i != 0; --i) {
+            Node* item = ancestors[i - 1].get();
+            RefPtr<Node> child = item->cloneNode(isTableElement(item));
+            appendNode(child, static_cast<Element *>(lastNode.get()));
+            lastNode = child.release();
+        }
+    }
+
+    // Handle the case of paragraphs with more than one node,
+    // cloning all the siblings until end.node() is reached.
+    
+    if (start.node() != end.node() && !start.node()->isDescendantOf(end.node())) {
+        // If end is not a descendant of outerNode we need to
+        // find the first common ancestor and adjust the insertion
+        // point accordingly.
+        while (!end.node()->isDescendantOf(outerNode)) {
+            outerNode = outerNode->parentNode();
+            topNode = topNode->parentNode();
+        }
+            
+        for (Node* n = start.node()->traverseNextSibling(outerNode); n; n = n->nextSibling()) {
+            if (n->parentNode() != start.node()->parentNode())
+                lastNode = topNode->lastChild();
+
+            RefPtr<Node> clonedNode = n->cloneNode(true);
+            insertNodeAfter(clonedNode, lastNode);
+            lastNode = clonedNode.release();
+            if (n == end.node() || end.node()->isDescendantOf(n))
+                break;
+        }
+    }
+}
+
+    
+// There are bugs in deletion when it removes a fully selected table/list.
+// It expands and removes the entire table/list, but will let content
+// before and after the table/list collapse onto one line.   
+// Deleting a paragraph will leave a placeholder. Remove it (and prune
+// empty or unrendered parents).
+
+void CompositeEditCommand::cleanupAfterDeletion()
+{
+    VisiblePosition caretAfterDelete = endingSelection().visibleStart();
+    if (isStartOfParagraph(caretAfterDelete) && isEndOfParagraph(caretAfterDelete)) {
+        // Note: We want the rightmost candidate.
+        Position position = caretAfterDelete.deepEquivalent().downstream();
+        Node* node = position.node();
+        // Normally deletion will leave a br as a placeholder.
+        if (node->hasTagName(brTag))
+            removeNodeAndPruneAncestors(node);
+        // If the selection to move was empty and in an empty block that 
+        // doesn't require a placeholder to prop itself open (like a bordered
+        // div or an li), remove it during the move (the list removal code
+        // expects this behavior).
+        else if (isBlock(node))
+            removeNodeAndPruneAncestors(node);
+        else if (lineBreakExistsAtPosition(position)) {
+            // There is a preserved '\n' at caretAfterDelete.
+            // We can safely assume this is a text node.
+            Text* textNode = static_cast<Text*>(node);
+            if (textNode->length() == 1)
+                removeNodeAndPruneAncestors(node);
+            else
+                deleteTextFromNode(textNode, position.deprecatedEditingOffset(), 1);
+        }
+    }
+}
+    
+// This is a version of moveParagraph that preserves style by keeping the original markup
+// It is currently used only by IndentOutdentCommand but it is meant to be used in the
+// future by several other commands such as InsertList and the align commands.
+// The blockElement parameter is the element to move the paragraph to,
+// outerNode is the top element of the paragraph hierarchy. 
+
+void CompositeEditCommand::moveParagraphWithClones(const VisiblePosition& startOfParagraphToMove, const VisiblePosition& endOfParagraphToMove, Element* blockElement, Node* outerNode)
+{
+    ASSERT(outerNode);
+    ASSERT(blockElement);
+
+    VisiblePosition beforeParagraph = startOfParagraphToMove.previous();
+    VisiblePosition afterParagraph(endOfParagraphToMove.next());
+    
+    // We upstream() the end and downstream() the start so that we don't include collapsed whitespace in the move.
+    // When we paste a fragment, spaces after the end and before the start are treated as though they were rendered.
+    Position start = startOfParagraphToMove.deepEquivalent().downstream();
+    Position end = endOfParagraphToMove.deepEquivalent().upstream();
+
+    cloneParagraphUnderNewElement(start, end, outerNode, blockElement);
+      
+    setEndingSelection(VisibleSelection(start, end, DOWNSTREAM));
+    deleteSelection(false, false, false, false);
+    
+    // There are bugs in deletion when it removes a fully selected table/list.
+    // It expands and removes the entire table/list, but will let content
+    // before and after the table/list collapse onto one line.
+       
+    cleanupAfterDeletion();
+    
+    // Add a br if pruning an empty block level element caused a collapse.  For example:
+    // foo^
+    // <div>bar</div>
+    // baz
+    // Imagine moving 'bar' to ^.  'bar' will be deleted and its div pruned.  That would
+    // cause 'baz' to collapse onto the line with 'foobar' unless we insert a br.
+    // Must recononicalize these two VisiblePositions after the pruning above.
+    beforeParagraph = VisiblePosition(beforeParagraph.deepEquivalent());
+    afterParagraph = VisiblePosition(afterParagraph.deepEquivalent());
+
+    if (beforeParagraph.isNotNull() && !isTableElement(beforeParagraph.deepEquivalent().node()) && (!isEndOfParagraph(beforeParagraph) || beforeParagraph == afterParagraph)) {
+        // FIXME: Trim text between beforeParagraph and afterParagraph if they aren't equal.
+        insertNodeAt(createBreakElement(document()), beforeParagraph.deepEquivalent());
+    }
+}
+    
+    
+// This moves a paragraph preserving its style.
+void CompositeEditCommand::moveParagraph(const VisiblePosition& startOfParagraphToMove, const VisiblePosition& endOfParagraphToMove, const VisiblePosition& destination, bool preserveSelection, bool preserveStyle)
+{
+    ASSERT(isStartOfParagraph(startOfParagraphToMove));
+    ASSERT(isEndOfParagraph(endOfParagraphToMove));
+    moveParagraphs(startOfParagraphToMove, endOfParagraphToMove, destination, preserveSelection, preserveStyle);
+}
+
+void CompositeEditCommand::moveParagraphs(const VisiblePosition& startOfParagraphToMove, const VisiblePosition& endOfParagraphToMove, const VisiblePosition& destination, bool preserveSelection, bool preserveStyle)
+{
+    if (startOfParagraphToMove == destination)
+        return;
+    
+    int startIndex = -1;
+    int endIndex = -1;
+    int destinationIndex = -1;
+    if (preserveSelection && !endingSelection().isNone()) {
+        VisiblePosition visibleStart = endingSelection().visibleStart();
+        VisiblePosition visibleEnd = endingSelection().visibleEnd();
+        
+        bool startAfterParagraph = comparePositions(visibleStart, endOfParagraphToMove) > 0;
+        bool endBeforeParagraph = comparePositions(visibleEnd, startOfParagraphToMove) < 0;
+        
+        if (!startAfterParagraph && !endBeforeParagraph) {
+            bool startInParagraph = comparePositions(visibleStart, startOfParagraphToMove) >= 0;
+            bool endInParagraph = comparePositions(visibleEnd, endOfParagraphToMove) <= 0;
+            
+            startIndex = 0;
+            if (startInParagraph) {
+                RefPtr<Range> startRange = Range::create(document(), rangeCompliantEquivalent(startOfParagraphToMove.deepEquivalent()), rangeCompliantEquivalent(visibleStart.deepEquivalent()));
+                startIndex = TextIterator::rangeLength(startRange.get(), true);
+            }
+
+            endIndex = 0;
+            if (endInParagraph) {
+                RefPtr<Range> endRange = Range::create(document(), rangeCompliantEquivalent(startOfParagraphToMove.deepEquivalent()), rangeCompliantEquivalent(visibleEnd.deepEquivalent()));
+                endIndex = TextIterator::rangeLength(endRange.get(), true);
+            }
+        }
+    }
+    
+    VisiblePosition beforeParagraph = startOfParagraphToMove.previous();
+    VisiblePosition afterParagraph(endOfParagraphToMove.next());
+
+    // We upstream() the end and downstream() the start so that we don't include collapsed whitespace in the move.
+    // When we paste a fragment, spaces after the end and before the start are treated as though they were rendered.
+    Position start = startOfParagraphToMove.deepEquivalent().downstream();
+    Position end = endOfParagraphToMove.deepEquivalent().upstream();
+    
+    // start and end can't be used directly to create a Range; they are "editing positions"
+    Position startRangeCompliant = rangeCompliantEquivalent(start);
+    Position endRangeCompliant = rangeCompliantEquivalent(end);
+    RefPtr<Range> range = Range::create(document(), startRangeCompliant.node(), startRangeCompliant.deprecatedEditingOffset(), endRangeCompliant.node(), endRangeCompliant.deprecatedEditingOffset());
+
+    // FIXME: This is an inefficient way to preserve style on nodes in the paragraph to move. It
+    // shouldn't matter though, since moved paragraphs will usually be quite small.
+    RefPtr<DocumentFragment> fragment;
+    // This used to use a ternary for initialization, but that confused some versions of GCC, see bug 37912
+    if (startOfParagraphToMove != endOfParagraphToMove)
+        fragment = createFragmentFromMarkup(document(), createMarkup(range.get(), 0, DoNotAnnotateForInterchange, true), "");
+
+    // A non-empty paragraph's style is moved when we copy and move it.  We don't move 
+    // anything if we're given an empty paragraph, but an empty paragraph can have style
+    // too, <div><b><br></b></div> for example.  Save it so that we can preserve it later.
+    RefPtr<CSSMutableStyleDeclaration> styleInEmptyParagraph;
+    if (startOfParagraphToMove == endOfParagraphToMove && preserveStyle) {
+        styleInEmptyParagraph = ApplyStyleCommand::editingStyleAtPosition(startOfParagraphToMove.deepEquivalent(), IncludeTypingStyle);
+        // The moved paragraph should assume the block style of the destination.
+        styleInEmptyParagraph->removeBlockProperties();
+    }
+    
+    // FIXME (5098931): We should add a new insert action "WebViewInsertActionMoved" and call shouldInsertFragment here.
+    
+    setEndingSelection(VisibleSelection(start, end, DOWNSTREAM));
+    deleteSelection(false, false, false, false);
+
+    ASSERT(destination.deepEquivalent().node()->inDocument());
+
+    cleanupAfterDeletion();
+    ASSERT(destination.deepEquivalent().node()->inDocument());
+
+    // Add a br if pruning an empty block level element caused a collapse. For example:
+    // foo^
+    // <div>bar</div>
+    // baz
+    // Imagine moving 'bar' to ^. 'bar' will be deleted and its div pruned. That would
+    // cause 'baz' to collapse onto the line with 'foobar' unless we insert a br.
+    // Must recononicalize these two VisiblePositions after the pruning above.
+    beforeParagraph = VisiblePosition(beforeParagraph.deepEquivalent());
+    afterParagraph = VisiblePosition(afterParagraph.deepEquivalent());
+    if (beforeParagraph.isNotNull() && (!isEndOfParagraph(beforeParagraph) || beforeParagraph == afterParagraph)) {
+        // FIXME: Trim text between beforeParagraph and afterParagraph if they aren't equal.
+        insertNodeAt(createBreakElement(document()), beforeParagraph.deepEquivalent());
+        // Need an updateLayout here in case inserting the br has split a text node.
+        updateLayout();
+    }
+        
+    RefPtr<Range> startToDestinationRange(Range::create(document(), Position(document(), 0), rangeCompliantEquivalent(destination.deepEquivalent())));
+    destinationIndex = TextIterator::rangeLength(startToDestinationRange.get(), true);
+    
+    setEndingSelection(destination);
+    ASSERT(endingSelection().isCaretOrRange());
+    applyCommandToComposite(ReplaceSelectionCommand::create(document(), fragment, true, false, !preserveStyle, false, true));
+    
+    // If the selection is in an empty paragraph, restore styles from the old empty paragraph to the new empty paragraph.
+    bool selectionIsEmptyParagraph = endingSelection().isCaret() && isStartOfParagraph(endingSelection().visibleStart()) && isEndOfParagraph(endingSelection().visibleStart());
+    if (styleInEmptyParagraph && selectionIsEmptyParagraph)
+        applyStyle(styleInEmptyParagraph.get());
+    
+    if (preserveSelection && startIndex != -1) {
+        // Fragment creation (using createMarkup) incorrectly uses regular
+        // spaces instead of nbsps for some spaces that were rendered (11475), which
+        // causes spaces to be collapsed during the move operation.  This results
+        // in a call to rangeFromLocationAndLength with a location past the end
+        // of the document (which will return null).
+        RefPtr<Range> start = TextIterator::rangeFromLocationAndLength(document()->documentElement(), destinationIndex + startIndex, 0, true);
+        RefPtr<Range> end = TextIterator::rangeFromLocationAndLength(document()->documentElement(), destinationIndex + endIndex, 0, true);
+        if (start && end)
+            setEndingSelection(VisibleSelection(start->startPosition(), end->startPosition(), DOWNSTREAM));
+    }
+}
+
+// FIXME: Send an appropriate shouldDeleteRange call.
+bool CompositeEditCommand::breakOutOfEmptyListItem()
+{
+    Node* emptyListItem = enclosingEmptyListItem(endingSelection().visibleStart());
+    if (!emptyListItem)
+        return false;
+
+    RefPtr<CSSMutableStyleDeclaration> style = ApplyStyleCommand::editingStyleAtPosition(endingSelection().start(), IncludeTypingStyle);
+
+    Node* listNode = emptyListItem->parentNode();
+    // FIXME: Can't we do something better when the immediate parent wasn't a list node?
+    if (!listNode
+        || (!listNode->hasTagName(ulTag) && !listNode->hasTagName(olTag))
+        || !listNode->isContentEditable())
+        return false;
+
+    RefPtr<Element> newBlock = 0;
+    if (Node* blockEnclosingList = listNode->parentNode()) {
+        if (blockEnclosingList->hasTagName(liTag)) { // listNode is inside another list item
+            if (visiblePositionAfterNode(blockEnclosingList) == visiblePositionAfterNode(listNode)) {
+                // If listNode appears at the end of the outer list item, then move listNode outside of this list item
+                // e.g. <ul><li>hello <ul><li><br></li></ul> </li></ul> should become <ul><li>hello</li> <ul><li><br></li></ul> </ul> after this section
+                // If listNode does NOT appear at the end, then we should consider it as a regular paragraph.
+                // e.g. <ul><li> <ul><li><br></li></ul> hello</li></ul> should become <ul><li> <div><br></div> hello</li></ul> at the end
+                splitElement(static_cast<Element*>(blockEnclosingList), listNode);
+                removeNodePreservingChildren(listNode->parentNode());
+                newBlock = createListItemElement(document());
+            }
+            // If listNode does NOT appear at the end of the outer list item, then behave as if in a regular paragraph.
+        } else if (blockEnclosingList->hasTagName(olTag) || blockEnclosingList->hasTagName(ulTag))
+            newBlock = createListItemElement(document());
+    }
+    if (!newBlock)
+        newBlock = createDefaultParagraphElement(document());
+
+    if (emptyListItem->renderer()->nextSibling()) {
+        // If emptyListItem follows another list item, split the list node.
+        if (emptyListItem->renderer()->previousSibling())
+            splitElement(static_cast<Element*>(listNode), emptyListItem);
+
+        // If emptyListItem is followed by other list item, then insert newBlock before the list node.
+        // Because we have splitted the element, emptyListItem is the first element in the list node.
+        // i.e. insert newBlock before ul or ol whose first element is emptyListItem
+        insertNodeBefore(newBlock, listNode);
+        removeNode(emptyListItem);
+    } else {
+        // When emptyListItem does not follow any list item, insert newBlock after the enclosing list node.
+        // Remove the enclosing node if emptyListItem is the only child; otherwise just remove emptyListItem.
+        insertNodeAfter(newBlock, listNode);
+        removeNode(emptyListItem->renderer()->previousSibling() ? emptyListItem : listNode);
+    }
+
+    appendBlockPlaceholder(newBlock);
+    setEndingSelection(VisibleSelection(Position(newBlock.get(), 0), DOWNSTREAM));
+
+    prepareEditingStyleToApplyAt(style.get(), endingSelection().start());
+    if (style->length())
+        applyStyle(style.get());
+    
+    return true;
+}
+
+// If the caret is in an empty quoted paragraph, and either there is nothing before that
+// paragraph, or what is before is unquoted, and the user presses delete, unquote that paragraph.
+bool CompositeEditCommand::breakOutOfEmptyMailBlockquotedParagraph()
+{
+    if (!endingSelection().isCaret())
+        return false;
+        
+    VisiblePosition caret(endingSelection().visibleStart());
+    Node* highestBlockquote = highestEnclosingNodeOfType(caret.deepEquivalent(), &isMailBlockquote);
+    if (!highestBlockquote)
+        return false;
+        
+    if (!isStartOfParagraph(caret) || !isEndOfParagraph(caret))
+        return false;
+    
+    VisiblePosition previous(caret.previous(true));
+    // Only move forward if there's nothing before the caret, or if there's unquoted content before it.
+    if (enclosingNodeOfType(previous.deepEquivalent(), &isMailBlockquote))
+        return false;
+    
+    RefPtr<Node> br = createBreakElement(document());
+    // We want to replace this quoted paragraph with an unquoted one, so insert a br
+    // to hold the caret before the highest blockquote.
+    insertNodeBefore(br, highestBlockquote);
+    VisiblePosition atBR(Position(br.get(), 0));
+    // If the br we inserted collapsed, for example foo<br><blockquote>...</blockquote>, insert
+    // a second one.
+    if (!isStartOfParagraph(atBR))
+        insertNodeBefore(createBreakElement(document()), br);
+    setEndingSelection(VisibleSelection(atBR));
+    
+    // If this is an empty paragraph there must be a line break here.
+    if (!lineBreakExistsAtVisiblePosition(caret))
+        return false;
+    
+    Position caretPos(caret.deepEquivalent());
+    // A line break is either a br or a preserved newline.
+    ASSERT(caretPos.node()->hasTagName(brTag) || (caretPos.node()->isTextNode() && caretPos.node()->renderer()->style()->preserveNewline()));
+    
+    if (caretPos.node()->hasTagName(brTag)) {
+        Position beforeBR(positionInParentBeforeNode(caretPos.node()));
+        removeNode(caretPos.node());
+        prune(beforeBR.node());
+    } else {
+        ASSERT(caretPos.deprecatedEditingOffset() == 0);
+        Text* textNode = static_cast<Text*>(caretPos.node());
+        Node* parentNode = textNode->parentNode();
+        // The preserved newline must be the first thing in the node, since otherwise the previous
+        // paragraph would be quoted, and we verified that it wasn't above.
+        deleteTextFromNode(textNode, 0, 1);
+        prune(parentNode);
+    }
+    
+    return true;
+}
+
+// Operations use this function to avoid inserting content into an anchor when at the start or the end of
+// that anchor, as in NSTextView.
+// FIXME: This is only an approximation of NSTextViews insertion behavior, which varies depending on how
+// the caret was made. 
+Position CompositeEditCommand::positionAvoidingSpecialElementBoundary(const Position& original)
+{
+    if (original.isNull())
+        return original;
+        
+    VisiblePosition visiblePos(original);
+    Node* enclosingAnchor = enclosingAnchorElement(original);
+    Position result = original;
+
+    if (!enclosingAnchor)
+        return result;
+
+    // Don't avoid block level anchors, because that would insert content into the wrong paragraph.
+    if (enclosingAnchor && !isBlock(enclosingAnchor)) {
+        VisiblePosition firstInAnchor(firstDeepEditingPositionForNode(enclosingAnchor));
+        VisiblePosition lastInAnchor(lastDeepEditingPositionForNode(enclosingAnchor));
+        // If visually just after the anchor, insert *inside* the anchor unless it's the last
+        // VisiblePosition in the document, to match NSTextView.
+        if (visiblePos == lastInAnchor) {
+            // Make sure anchors are pushed down before avoiding them so that we don't
+            // also avoid structural elements like lists and blocks (5142012).
+            if (original.node() != enclosingAnchor && original.node()->parentNode() != enclosingAnchor) {
+                pushAnchorElementDown(enclosingAnchor);
+                enclosingAnchor = enclosingAnchorElement(original);
+                if (!enclosingAnchor)
+                    return original;
+            }
+            // Don't insert outside an anchor if doing so would skip over a line break.  It would
+            // probably be safe to move the line break so that we could still avoid the anchor here.
+            Position downstream(visiblePos.deepEquivalent().downstream());
+            if (lineBreakExistsAtVisiblePosition(visiblePos) && downstream.node()->isDescendantOf(enclosingAnchor))
+                return original;
+            
+            result = positionInParentAfterNode(enclosingAnchor);
+        }
+        // If visually just before an anchor, insert *outside* the anchor unless it's the first
+        // VisiblePosition in a paragraph, to match NSTextView.
+        if (visiblePos == firstInAnchor) {
+            // Make sure anchors are pushed down before avoiding them so that we don't
+            // also avoid structural elements like lists and blocks (5142012).
+            if (original.node() != enclosingAnchor && original.node()->parentNode() != enclosingAnchor) {
+                pushAnchorElementDown(enclosingAnchor);
+                enclosingAnchor = enclosingAnchorElement(original);
+            }
+            if (!enclosingAnchor)
+                return original;
+
+            result = positionInParentBeforeNode(enclosingAnchor);
+        }
+    }
+        
+    if (result.isNull() || !editableRootForPosition(result))
+        result = original;
+    
+    return result;
+}
+
+// Splits the tree parent by parent until we reach the specified ancestor. We use VisiblePositions
+// to determine if the split is necessary. Returns the last split node.
+PassRefPtr<Node> CompositeEditCommand::splitTreeToNode(Node* start, Node* end, bool splitAncestor)
+{
+    ASSERT(start != end);
+
+    RefPtr<Node> node;
+    for (node = start; node && node->parent() != end; node = node->parent()) {
+        VisiblePosition positionInParent(Position(node->parent(), 0), DOWNSTREAM);
+        VisiblePosition positionInNode(Position(node, 0), DOWNSTREAM);
+        if (positionInParent != positionInNode)
+            applyCommandToComposite(SplitElementCommand::create(static_cast<Element*>(node->parent()), node));
+    }
+    if (splitAncestor) {
+        splitElement(static_cast<Element*>(end), node);
+        return node->parent();
+    }
+    return node.release();
+}
+
+PassRefPtr<Element> createBlockPlaceholderElement(Document* document)
+{
+    RefPtr<Element> breakNode = document->createElement(brTag, false);
+    return breakNode.release();
+}
+
+} // namespace WebCore