Merge WebKit at r75315: Initial merge by git.

Change-Id: I570314b346ce101c935ed22a626b48c2af266b84

1 files changed, 2557 insertions, 0 deletions

diff --git a/Source/WebCore/editing/TextIterator.cpp b/Source/WebCore/editing/TextIterator.cpp
new file mode 100644
index 0000000..7e41420
--- /dev/null
+++ b/Source/WebCore/editing/TextIterator.cpp
@@ -0,0 +1,2557 @@
+/*
+ * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
+ * Copyright (C) 2005 Alexey Proskuryakov.
+ *
+ * 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 "TextIterator.h"
+
+#include "CharacterNames.h"
+#include "Document.h"
+#include "HTMLElement.h"
+#include "HTMLNames.h"
+#include "htmlediting.h"
+#include "InlineTextBox.h"
+#include "Range.h"
+#include "RenderTableCell.h"
+#include "RenderTableRow.h"
+#include "RenderTextControl.h"
+#include "RenderTextFragment.h"
+#include "TextBoundaries.h"
+#include "TextBreakIterator.h"
+#include "VisiblePosition.h"
+#include "visible_units.h"
+
+#if USE(ICU_UNICODE) && !UCONFIG_NO_COLLATION
+#include "TextBreakIteratorInternalICU.h"
+#include <unicode/usearch.h>
+#endif
+
+using namespace WTF::Unicode;
+using namespace std;
+
+namespace WebCore {
+
+using namespace HTMLNames;
+
+// Buffer that knows how to compare with a search target.
+// Keeps enough of the previous text to be able to search in the future, but no more.
+// Non-breaking spaces are always equal to normal spaces.
+// Case folding is also done if the CaseInsensitive option is specified.
+// Matches are further filtered if the AtWordStarts option is specified, although some
+// matches inside a word are permitted if TreatMedialCapitalAsWordStart is specified as well.
+class SearchBuffer : public Noncopyable {
+public:
+    SearchBuffer(const String& target, FindOptions);
+    ~SearchBuffer();
+
+    // Returns number of characters appended; guaranteed to be in the range [1, length].
+    size_t append(const UChar*, size_t length);
+    bool needsMoreContext() const;
+    void prependContext(const UChar*, size_t length);
+    void reachedBreak();
+
+    // Result is the size in characters of what was found.
+    // And <startOffset> is the number of characters back to the start of what was found.
+    size_t search(size_t& startOffset);
+    bool atBreak() const;
+
+#if USE(ICU_UNICODE) && !UCONFIG_NO_COLLATION
+
+private:
+    bool isBadMatch(const UChar*, size_t length) const;
+    bool isWordStartMatch(size_t start, size_t length) const;
+
+    String m_target;
+    FindOptions m_options;
+
+    Vector<UChar> m_buffer;
+    size_t m_overlap;
+    size_t m_prefixLength;
+    bool m_atBreak;
+    bool m_needsMoreContext;
+
+    bool m_targetRequiresKanaWorkaround;
+    Vector<UChar> m_normalizedTarget;
+    mutable Vector<UChar> m_normalizedMatch;
+
+#else
+
+private:
+    void append(UChar, bool isCharacterStart);
+    size_t length() const;
+
+    String m_target;
+    FindOptions m_options;
+
+    Vector<UChar> m_buffer;
+    Vector<bool> m_isCharacterStartBuffer;
+    bool m_isBufferFull;
+    size_t m_cursor;
+
+#endif
+};
+
+// --------
+
+static const unsigned bitsInWord = sizeof(unsigned) * 8;
+static const unsigned bitInWordMask = bitsInWord - 1;
+
+BitStack::BitStack()
+    : m_size(0)
+{
+}
+
+BitStack::~BitStack()
+{
+}
+
+void BitStack::push(bool bit)
+{
+    unsigned index = m_size / bitsInWord;
+    unsigned shift = m_size & bitInWordMask;
+    if (!shift && index == m_words.size()) {
+        m_words.grow(index + 1);
+        m_words[index] = 0;
+    }
+    unsigned& word = m_words[index];
+    unsigned mask = 1U << shift;
+    if (bit)
+        word |= mask;
+    else
+        word &= ~mask;
+    ++m_size;
+}
+
+void BitStack::pop()
+{
+    if (m_size)
+        --m_size;
+}
+
+bool BitStack::top() const
+{
+    if (!m_size)
+        return false;
+    unsigned shift = (m_size - 1) & bitInWordMask;
+    return m_words.last() & (1U << shift);
+}
+
+unsigned BitStack::size() const
+{
+    return m_size;
+}
+
+// --------
+
+#if !ASSERT_DISABLED
+
+static unsigned depthCrossingShadowBoundaries(Node* node)
+{
+    unsigned depth = 0;
+    for (Node* parent = node->parentOrHostNode(); parent; parent = parent->parentOrHostNode())
+        ++depth;
+    return depth;
+}
+
+#endif
+
+// This function is like Range::pastLastNode, except for the fact that it can climb up out of shadow trees.
+static Node* nextInPreOrderCrossingShadowBoundaries(Node* rangeEndContainer, int rangeEndOffset)
+{
+    if (!rangeEndContainer)
+        return 0;
+    if (rangeEndOffset >= 0 && !rangeEndContainer->offsetInCharacters()) {
+        if (Node* next = rangeEndContainer->childNode(rangeEndOffset))
+            return next;
+    }
+    for (Node* node = rangeEndContainer; node; node = node->parentOrHostNode()) {
+        if (Node* next = node->nextSibling())
+            return next;
+    }
+    return 0;
+}
+
+static Node* previousInPostOrderCrossingShadowBoundaries(Node* rangeStartContainer, int rangeStartOffset)
+{
+    if (!rangeStartContainer)
+        return 0;
+    if (rangeStartOffset > 0 && !rangeStartContainer->offsetInCharacters()) {
+        if (Node* previous = rangeStartContainer->childNode(rangeStartOffset - 1))
+            return previous;
+    }
+    for (Node* node = rangeStartContainer; node; node = node->parentOrHostNode()) {
+        if (Node* previous = node->previousSibling())
+            return previous;
+    }
+    return 0;
+}
+
+// --------
+
+static inline bool fullyClipsContents(Node* node)
+{
+    RenderObject* renderer = node->renderer();
+    if (!renderer || !renderer->isBox() || !renderer->hasOverflowClip())
+        return false;
+    return toRenderBox(renderer)->size().isEmpty();
+}
+
+static inline bool ignoresContainerClip(Node* node)
+{
+    RenderObject* renderer = node->renderer();
+    if (!renderer || renderer->isText())
+        return false;
+    EPosition position = renderer->style()->position();
+    return position == AbsolutePosition || position == FixedPosition;
+}
+
+static void pushFullyClippedState(BitStack& stack, Node* node)
+{
+    ASSERT(stack.size() == depthCrossingShadowBoundaries(node));
+
+    // Push true if this node full clips its contents, or if a parent already has fully
+    // clipped and this is not a node that ignores its container's clip.
+    stack.push(fullyClipsContents(node) || (stack.top() && !ignoresContainerClip(node)));
+}
+
+static void setUpFullyClippedStack(BitStack& stack, Node* node)
+{
+    // Put the nodes in a vector so we can iterate in reverse order.
+    Vector<Node*, 100> ancestry;
+    for (Node* parent = node->parentOrHostNode(); parent; parent = parent->parentOrHostNode())
+        ancestry.append(parent);
+
+    // Call pushFullyClippedState on each node starting with the earliest ancestor.
+    size_t size = ancestry.size();
+    for (size_t i = 0; i < size; ++i)
+        pushFullyClippedState(stack, ancestry[size - i - 1]);
+    pushFullyClippedState(stack, node);
+
+    ASSERT(stack.size() == 1 + depthCrossingShadowBoundaries(node));
+}
+
+// --------
+
+TextIterator::TextIterator()
+    : m_startContainer(0)
+    , m_startOffset(0)
+    , m_endContainer(0)
+    , m_endOffset(0)
+    , m_positionNode(0)
+    , m_textCharacters(0)
+    , m_textLength(0)
+    , m_remainingTextBox(0)
+    , m_firstLetterText(0)
+    , m_lastCharacter(0)
+    , m_emitsCharactersBetweenAllVisiblePositions(false)
+    , m_entersTextControls(false)
+    , m_emitsTextWithoutTranscoding(false)
+    , m_handledFirstLetter(false)
+    , m_ignoresStyleVisibility(false)
+{
+}
+
+TextIterator::TextIterator(const Range* r, TextIteratorBehavior behavior)
+    : m_startContainer(0)
+    , m_startOffset(0)
+    , m_endContainer(0)
+    , m_endOffset(0)
+    , m_positionNode(0)
+    , m_textCharacters(0)
+    , m_textLength(0)
+    , m_remainingTextBox(0)
+    , m_firstLetterText(0)
+    , m_emitsCharactersBetweenAllVisiblePositions(behavior & TextIteratorEmitsCharactersBetweenAllVisiblePositions)
+    , m_entersTextControls(behavior & TextIteratorEntersTextControls)
+    , m_emitsTextWithoutTranscoding(behavior & TextIteratorEmitsTextsWithoutTranscoding)
+    , m_handledFirstLetter(false)
+    , m_ignoresStyleVisibility(behavior & TextIteratorIgnoresStyleVisibility)
+{
+    // FIXME: should support TextIteratorEndsAtEditingBoundary http://webkit.org/b/43609
+    ASSERT(behavior != TextIteratorEndsAtEditingBoundary);
+
+    if (!r)
+        return;
+
+    // get and validate the range endpoints
+    Node* startContainer = r->startContainer();
+    if (!startContainer)
+        return;
+    int startOffset = r->startOffset();
+    Node* endContainer = r->endContainer();
+    int endOffset = r->endOffset();
+
+    // Callers should be handing us well-formed ranges. If we discover that this isn't
+    // the case, we could consider changing this assertion to an early return.
+    ASSERT(r->boundaryPointsValid());
+
+    // remember range - this does not change
+    m_startContainer = startContainer;
+    m_startOffset = startOffset;
+    m_endContainer = endContainer;
+    m_endOffset = endOffset;
+
+    // set up the current node for processing
+    m_node = r->firstNode();
+    if (!m_node)
+        return;
+    setUpFullyClippedStack(m_fullyClippedStack, m_node);
+    m_offset = m_node == m_startContainer ? m_startOffset : 0;
+    m_handledNode = false;
+    m_handledChildren = false;
+
+    // calculate first out of bounds node
+    m_pastEndNode = nextInPreOrderCrossingShadowBoundaries(endContainer, endOffset);
+
+    // initialize node processing state
+    m_needsAnotherNewline = false;
+    m_textBox = 0;
+
+    // initialize record of previous node processing
+    m_hasEmitted = false;
+    m_lastTextNode = 0;
+    m_lastTextNodeEndedWithCollapsedSpace = false;
+    m_lastCharacter = 0;
+
+#ifndef NDEBUG
+    // need this just because of the assert in advance()
+    m_positionNode = m_node;
+#endif
+
+    // identify the first run
+    advance();
+}
+
+TextIterator::~TextIterator()
+{
+}
+
+void TextIterator::advance()
+{
+    // reset the run information
+    m_positionNode = 0;
+    m_textLength = 0;
+
+    // handle remembered node that needed a newline after the text node's newline
+    if (m_needsAnotherNewline) {
+        // Emit the extra newline, and position it *inside* m_node, after m_node's 
+        // contents, in case it's a block, in the same way that we position the first 
+        // newline.  The range for the emitted newline should start where the line 
+        // break begins.
+        // FIXME: It would be cleaner if we emitted two newlines during the last 
+        // iteration, instead of using m_needsAnotherNewline.
+        Node* baseNode = m_node->lastChild() ? m_node->lastChild() : m_node;
+        emitCharacter('\n', baseNode->parentNode(), baseNode, 1, 1);
+        m_needsAnotherNewline = false;
+        return;
+    }
+
+    if (!m_textBox && m_remainingTextBox) {
+        m_textBox = m_remainingTextBox;
+        m_remainingTextBox = 0;
+        m_firstLetterText = 0;
+        m_offset = 0;
+    }
+    // handle remembered text box
+    if (m_textBox) {
+        handleTextBox();
+        if (m_positionNode)
+            return;
+    }
+
+    while (m_node && m_node != m_pastEndNode) {
+        // if the range ends at offset 0 of an element, represent the
+        // position, but not the content, of that element e.g. if the
+        // node is a blockflow element, emit a newline that
+        // precedes the element
+        if (m_node == m_endContainer && m_endOffset == 0) {
+            representNodeOffsetZero();
+            m_node = 0;
+            return;
+        }
+        
+        RenderObject* renderer = m_node->renderer();
+        if (!renderer) {
+            m_handledNode = true;
+            m_handledChildren = true;
+        } else {
+            // handle current node according to its type
+            if (!m_handledNode) {
+                if (renderer->isText() && m_node->nodeType() == Node::TEXT_NODE) // FIXME: What about CDATA_SECTION_NODE?
+                    m_handledNode = handleTextNode();
+                else if (renderer && (renderer->isImage() || renderer->isWidget() ||
+                         (renderer->node() && renderer->node()->isElementNode() &&
+                          static_cast<Element*>(renderer->node())->isFormControlElement())))
+                    m_handledNode = handleReplacedElement();
+                else
+                    m_handledNode = handleNonTextNode();
+                if (m_positionNode)
+                    return;
+            }
+        }
+
+        // find a new current node to handle in depth-first manner,
+        // calling exitNode() as we come back thru a parent node
+        Node* next = m_handledChildren ? 0 : m_node->firstChild();
+        m_offset = 0;
+        if (!next) {
+            next = m_node->nextSibling();
+            if (!next) {
+                bool pastEnd = m_node->traverseNextNode() == m_pastEndNode;
+                Node* parentNode = m_node->parentOrHostNode();
+                while (!next && parentNode) {
+                    if ((pastEnd && parentNode == m_endContainer) || m_endContainer->isDescendantOf(parentNode))
+                        return;
+                    bool haveRenderer = m_node->renderer();
+                    m_node = parentNode;
+                    m_fullyClippedStack.pop();
+                    parentNode = m_node->parentOrHostNode();
+                    if (haveRenderer)
+                        exitNode();
+                    if (m_positionNode) {
+                        m_handledNode = true;
+                        m_handledChildren = true;
+                        return;
+                    }
+                    next = m_node->nextSibling();
+                }
+            }
+            m_fullyClippedStack.pop();            
+        }
+
+        // set the new current node
+        m_node = next;
+        if (m_node)
+            pushFullyClippedState(m_fullyClippedStack, m_node);
+        m_handledNode = false;
+        m_handledChildren = false;
+        m_handledFirstLetter = false;
+        m_firstLetterText = 0;
+
+        // how would this ever be?
+        if (m_positionNode)
+            return;
+    }
+}
+
+bool TextIterator::handleTextNode()
+{
+    if (m_fullyClippedStack.top() && !m_ignoresStyleVisibility)
+        return false;
+
+    RenderText* renderer = toRenderText(m_node->renderer());
+        
+    m_lastTextNode = m_node;
+    String str = renderer->text();
+
+    // handle pre-formatted text
+    if (!renderer->style()->collapseWhiteSpace()) {
+        int runStart = m_offset;
+        if (m_lastTextNodeEndedWithCollapsedSpace && hasVisibleTextNode(renderer)) {
+            emitCharacter(' ', m_node, 0, runStart, runStart);
+            return false;
+        }
+        if (!m_handledFirstLetter && renderer->isTextFragment()) {
+            handleTextNodeFirstLetter(static_cast<RenderTextFragment*>(renderer));
+            if (m_firstLetterText) {
+                String firstLetter = m_firstLetterText->text();
+                emitText(m_node, m_firstLetterText, m_offset, m_offset + firstLetter.length());
+                m_firstLetterText = 0;
+                m_textBox = 0;
+                return false;
+            }
+        }
+        if (renderer->style()->visibility() != VISIBLE && !m_ignoresStyleVisibility)
+            return false;
+        int strLength = str.length();
+        int end = (m_node == m_endContainer) ? m_endOffset : INT_MAX;
+        int runEnd = min(strLength, end);
+
+        if (runStart >= runEnd)
+            return true;
+
+        emitText(m_node, runStart, runEnd);
+        return true;
+    }
+
+    if (!renderer->firstTextBox() && str.length() > 0) {
+        if (!m_handledFirstLetter && renderer->isTextFragment()) {
+            handleTextNodeFirstLetter(static_cast<RenderTextFragment*>(renderer));
+            if (m_firstLetterText) {
+                handleTextBox();
+                return false;
+            }
+        }
+        if (renderer->style()->visibility() != VISIBLE && !m_ignoresStyleVisibility)
+            return false;
+        m_lastTextNodeEndedWithCollapsedSpace = true; // entire block is collapsed space
+        return true;
+    }
+
+    // Used when text boxes are out of order (Hebrew/Arabic w/ embeded LTR text)
+    if (renderer->containsReversedText()) {
+        m_sortedTextBoxes.clear();
+        for (InlineTextBox* textBox = renderer->firstTextBox(); textBox; textBox = textBox->nextTextBox()) {
+            m_sortedTextBoxes.append(textBox);
+        }
+        std::sort(m_sortedTextBoxes.begin(), m_sortedTextBoxes.end(), InlineTextBox::compareByStart); 
+        m_sortedTextBoxesPosition = 0;
+    }
+    
+    m_textBox = renderer->containsReversedText() ? (m_sortedTextBoxes.isEmpty() ? 0 : m_sortedTextBoxes[0]) : renderer->firstTextBox();
+    if (!m_handledFirstLetter && renderer->isTextFragment() && !m_offset)
+        handleTextNodeFirstLetter(static_cast<RenderTextFragment*>(renderer));
+    handleTextBox();
+    return true;
+}
+
+void TextIterator::handleTextBox()
+{    
+    RenderText* renderer = m_firstLetterText ? m_firstLetterText : toRenderText(m_node->renderer());
+    if (renderer->style()->visibility() != VISIBLE && !m_ignoresStyleVisibility) {
+        m_textBox = 0;
+        return;
+    }
+    String str = renderer->text();
+    unsigned start = m_offset;
+    unsigned end = (m_node == m_endContainer) ? static_cast<unsigned>(m_endOffset) : UINT_MAX;
+    while (m_textBox) {
+        unsigned textBoxStart = m_textBox->start();
+        unsigned runStart = max(textBoxStart, start);
+
+        // Check for collapsed space at the start of this run.
+        InlineTextBox* firstTextBox = renderer->containsReversedText() ? m_sortedTextBoxes[0] : renderer->firstTextBox();
+        bool needSpace = m_lastTextNodeEndedWithCollapsedSpace
+            || (m_textBox == firstTextBox && textBoxStart == runStart && runStart > 0);
+        if (needSpace && !isCollapsibleWhitespace(m_lastCharacter) && m_lastCharacter) {
+            if (m_lastTextNode == m_node && runStart > 0 && str[runStart - 1] == ' ') {
+                unsigned spaceRunStart = runStart - 1;
+                while (spaceRunStart > 0 && str[spaceRunStart - 1] == ' ')
+                    --spaceRunStart;
+                emitText(m_node, spaceRunStart, spaceRunStart + 1);
+            } else
+                emitCharacter(' ', m_node, 0, runStart, runStart);
+            return;
+        }
+        unsigned textBoxEnd = textBoxStart + m_textBox->len();
+        unsigned runEnd = min(textBoxEnd, end);
+        
+        // Determine what the next text box will be, but don't advance yet
+        InlineTextBox* nextTextBox = 0;
+        if (renderer->containsReversedText()) {
+            if (m_sortedTextBoxesPosition + 1 < m_sortedTextBoxes.size())
+                nextTextBox = m_sortedTextBoxes[m_sortedTextBoxesPosition + 1];
+        } else 
+            nextTextBox = m_textBox->nextTextBox();
+
+        if (runStart < runEnd) {
+            // Handle either a single newline character (which becomes a space),
+            // or a run of characters that does not include a newline.
+            // This effectively translates newlines to spaces without copying the text.
+            if (str[runStart] == '\n') {
+                emitCharacter(' ', m_node, 0, runStart, runStart + 1);
+                m_offset = runStart + 1;
+            } else {
+                size_t subrunEnd = str.find('\n', runStart);
+                if (subrunEnd == notFound || subrunEnd > runEnd)
+                    subrunEnd = runEnd;
+    
+                m_offset = subrunEnd;
+                emitText(m_node, renderer, runStart, subrunEnd);
+            }
+
+            // If we are doing a subrun that doesn't go to the end of the text box,
+            // come back again to finish handling this text box; don't advance to the next one.
+            if (static_cast<unsigned>(m_positionEndOffset) < textBoxEnd)
+                return;
+
+            // Advance and return
+            unsigned nextRunStart = nextTextBox ? nextTextBox->start() : str.length();
+            if (nextRunStart > runEnd)
+                m_lastTextNodeEndedWithCollapsedSpace = true; // collapsed space between runs or at the end
+            m_textBox = nextTextBox;
+            if (renderer->containsReversedText())
+                ++m_sortedTextBoxesPosition;
+            return;
+        }
+        // Advance and continue
+        m_textBox = nextTextBox;
+        if (renderer->containsReversedText())
+            ++m_sortedTextBoxesPosition;
+    }
+    if (!m_textBox && m_remainingTextBox) {
+        m_textBox = m_remainingTextBox;
+        m_remainingTextBox = 0;
+        m_firstLetterText = 0;
+        m_offset = 0;
+        handleTextBox();
+    }
+}
+
+void TextIterator::handleTextNodeFirstLetter(RenderTextFragment* renderer)
+{
+    if (renderer->firstLetter()) {
+        RenderObject* r = renderer->firstLetter();
+        if (r->style()->visibility() != VISIBLE && !m_ignoresStyleVisibility)
+            return;
+        for (RenderObject *currChild = r->firstChild(); currChild; currChild->nextSibling()) {
+            if (currChild->isText()) {
+                RenderText* firstLetter = toRenderText(currChild);
+                m_handledFirstLetter = true;
+                m_remainingTextBox = m_textBox;
+                m_textBox = firstLetter->firstTextBox();
+                m_firstLetterText = firstLetter;
+                return;
+            }
+        }
+    }
+    m_handledFirstLetter = true;
+}
+
+bool TextIterator::handleReplacedElement()
+{
+    if (m_fullyClippedStack.top())
+        return false;
+
+    RenderObject* renderer = m_node->renderer();
+    if (renderer->style()->visibility() != VISIBLE && !m_ignoresStyleVisibility)
+        return false;
+
+    if (m_lastTextNodeEndedWithCollapsedSpace) {
+        emitCharacter(' ', m_lastTextNode->parentNode(), m_lastTextNode, 1, 1);
+        return false;
+    }
+
+    if (m_entersTextControls && renderer->isTextControl()) {
+        if (HTMLElement* innerTextElement = toRenderTextControl(renderer)->innerTextElement()) {
+            m_node = innerTextElement->shadowTreeRootNode();
+            pushFullyClippedState(m_fullyClippedStack, m_node);
+            m_offset = 0;
+            return false;
+        }
+    }
+
+    m_hasEmitted = true;
+
+    if (m_emitsCharactersBetweenAllVisiblePositions) {
+        // We want replaced elements to behave like punctuation for boundary 
+        // finding, and to simply take up space for the selection preservation 
+        // code in moveParagraphs, so we use a comma.
+        emitCharacter(',', m_node->parentNode(), m_node, 0, 1);
+        return true;
+    }
+
+    m_positionNode = m_node->parentNode();
+    m_positionOffsetBaseNode = m_node;
+    m_positionStartOffset = 0;
+    m_positionEndOffset = 1;
+
+    m_textCharacters = 0;
+    m_textLength = 0;
+
+    m_lastCharacter = 0;
+
+    return true;
+}
+
+bool TextIterator::hasVisibleTextNode(RenderText* renderer)
+{
+    if (renderer->style()->visibility() == VISIBLE)
+        return true;
+    if (renderer->isTextFragment()) {
+        RenderTextFragment* fragment = static_cast<RenderTextFragment*>(renderer);
+        if (fragment->firstLetter() && fragment->firstLetter()->style()->visibility() == VISIBLE)
+            return true;
+    }
+    return false;
+}
+
+static bool shouldEmitTabBeforeNode(Node* node)
+{
+    RenderObject* r = node->renderer();
+    
+    // Table cells are delimited by tabs.
+    if (!r || !isTableCell(node))
+        return false;
+    
+    // Want a tab before every cell other than the first one
+    RenderTableCell* rc = toRenderTableCell(r);
+    RenderTable* t = rc->table();
+    return t && (t->cellBefore(rc) || t->cellAbove(rc));
+}
+
+static bool shouldEmitNewlineForNode(Node* node)
+{
+    // br elements are represented by a single newline.
+    RenderObject* r = node->renderer();
+    if (!r)
+        return node->hasTagName(brTag);
+        
+    return r->isBR();
+}
+
+static bool shouldEmitNewlinesBeforeAndAfterNode(Node* node)
+{
+    // Block flow (versus inline flow) is represented by having
+    // a newline both before and after the element.
+    RenderObject* r = node->renderer();
+    if (!r) {
+        return (node->hasTagName(blockquoteTag)
+                || node->hasTagName(ddTag)
+                || node->hasTagName(divTag)
+                || node->hasTagName(dlTag)
+                || node->hasTagName(dtTag)
+                || node->hasTagName(h1Tag)
+                || node->hasTagName(h2Tag)
+                || node->hasTagName(h3Tag)
+                || node->hasTagName(h4Tag)
+                || node->hasTagName(h5Tag)
+                || node->hasTagName(h6Tag)
+                || node->hasTagName(hrTag)
+                || node->hasTagName(liTag)
+                || node->hasTagName(listingTag)
+                || node->hasTagName(olTag)
+                || node->hasTagName(pTag)
+                || node->hasTagName(preTag)
+                || node->hasTagName(trTag)
+                || node->hasTagName(ulTag));
+    }
+    
+    // Need to make an exception for table cells, because they are blocks, but we
+    // want them tab-delimited rather than having newlines before and after.
+    if (isTableCell(node))
+        return false;
+    
+    // Need to make an exception for table row elements, because they are neither
+    // "inline" or "RenderBlock", but we want newlines for them.
+    if (r->isTableRow()) {
+        RenderTable* t = toRenderTableRow(r)->table();
+        if (t && !t->isInline())
+            return true;
+    }
+    
+    return !r->isInline() && r->isRenderBlock() && !r->isFloatingOrPositioned() && !r->isBody();
+}
+
+static bool shouldEmitNewlineAfterNode(Node* node)
+{
+    // FIXME: It should be better but slower to create a VisiblePosition here.
+    if (!shouldEmitNewlinesBeforeAndAfterNode(node))
+        return false;
+    // Check if this is the very last renderer in the document.
+    // If so, then we should not emit a newline.
+    while ((node = node->traverseNextSibling()))
+        if (node->renderer())
+            return true;
+    return false;
+}
+
+static bool shouldEmitNewlineBeforeNode(Node* node)
+{
+    return shouldEmitNewlinesBeforeAndAfterNode(node); 
+}
+
+static bool shouldEmitExtraNewlineForNode(Node* node)
+{
+    // When there is a significant collapsed bottom margin, emit an extra
+    // newline for a more realistic result.  We end up getting the right
+    // result even without margin collapsing. For example: <div><p>text</p></div>
+    // will work right even if both the <div> and the <p> have bottom margins.
+    RenderObject* r = node->renderer();
+    if (!r || !r->isBox())
+        return false;
+    
+    // NOTE: We only do this for a select set of nodes, and fwiw WinIE appears
+    // not to do this at all
+    if (node->hasTagName(h1Tag)
+        || node->hasTagName(h2Tag)
+        || node->hasTagName(h3Tag)
+        || node->hasTagName(h4Tag)
+        || node->hasTagName(h5Tag)
+        || node->hasTagName(h6Tag)
+        || node->hasTagName(pTag)) {
+        RenderStyle* style = r->style();
+        if (style) {
+            int bottomMargin = toRenderBox(r)->collapsedMarginAfter();
+            int fontSize = style->fontDescription().computedPixelSize();
+            if (bottomMargin * 2 >= fontSize)
+                return true;
+        }
+    }
+    
+    return false;
+}
+
+static int collapsedSpaceLength(RenderText* renderer, int textEnd)
+{
+    const UChar* characters = renderer->text()->characters();
+    int length = renderer->text()->length();
+    for (int i = textEnd; i < length; ++i) {
+        if (!renderer->style()->isCollapsibleWhiteSpace(characters[i]))
+            return i - textEnd;
+    }
+
+    return length - textEnd;
+}
+
+static int maxOffsetIncludingCollapsedSpaces(Node* node)
+{
+    int offset = caretMaxOffset(node);
+
+    if (node->renderer() && node->renderer()->isText())
+        offset += collapsedSpaceLength(toRenderText(node->renderer()), offset);
+
+    return offset;
+}
+
+// Whether or not we should emit a character as we enter m_node (if it's a container) or as we hit it (if it's atomic).
+bool TextIterator::shouldRepresentNodeOffsetZero()
+{
+    if (m_emitsCharactersBetweenAllVisiblePositions && m_node->renderer() && m_node->renderer()->isTable())
+        return true;
+        
+    // Leave element positioned flush with start of a paragraph
+    // (e.g. do not insert tab before a table cell at the start of a paragraph)
+    if (m_lastCharacter == '\n')
+        return false;
+    
+    // Otherwise, show the position if we have emitted any characters
+    if (m_hasEmitted)
+        return true;
+    
+    // We've not emitted anything yet. Generally, there is no need for any positioning then.
+    // The only exception is when the element is visually not in the same line as
+    // the start of the range (e.g. the range starts at the end of the previous paragraph).
+    // NOTE: Creating VisiblePositions and comparing them is relatively expensive, so we
+    // make quicker checks to possibly avoid that. Another check that we could make is
+    // is whether the inline vs block flow changed since the previous visible element.
+    // I think we're already in a special enough case that that won't be needed, tho.
+
+    // No character needed if this is the first node in the range.
+    if (m_node == m_startContainer)
+        return false;
+    
+    // If we are outside the start container's subtree, assume we need to emit.
+    // FIXME: m_startContainer could be an inline block
+    if (!m_node->isDescendantOf(m_startContainer))
+        return true;
+
+    // If we started as m_startContainer offset 0 and the current node is a descendant of
+    // the start container, we already had enough context to correctly decide whether to
+    // emit after a preceding block. We chose not to emit (m_hasEmitted is false),
+    // so don't second guess that now.
+    // NOTE: Is this really correct when m_node is not a leftmost descendant? Probably
+    // immaterial since we likely would have already emitted something by now.
+    if (m_startOffset == 0)
+        return false;
+        
+    // If this node is unrendered or invisible the VisiblePosition checks below won't have much meaning.
+    // Additionally, if the range we are iterating over contains huge sections of unrendered content, 
+    // we would create VisiblePositions on every call to this function without this check.
+    if (!m_node->renderer() || m_node->renderer()->style()->visibility() != VISIBLE)
+        return false;
+    
+    // The startPos.isNotNull() check is needed because the start could be before the body,
+    // and in that case we'll get null. We don't want to put in newlines at the start in that case.
+    // The currPos.isNotNull() check is needed because positions in non-HTML content
+    // (like SVG) do not have visible positions, and we don't want to emit for them either.
+    VisiblePosition startPos = VisiblePosition(m_startContainer, m_startOffset, DOWNSTREAM);
+    VisiblePosition currPos = VisiblePosition(m_node, 0, DOWNSTREAM);
+    return startPos.isNotNull() && currPos.isNotNull() && !inSameLine(startPos, currPos);
+}
+
+bool TextIterator::shouldEmitSpaceBeforeAndAfterNode(Node* node)
+{
+    return node->renderer() && node->renderer()->isTable() && (node->renderer()->isInline() || m_emitsCharactersBetweenAllVisiblePositions);
+}
+
+void TextIterator::representNodeOffsetZero()
+{
+    // Emit a character to show the positioning of m_node.
+    
+    // When we haven't been emitting any characters, shouldRepresentNodeOffsetZero() can 
+    // create VisiblePositions, which is expensive.  So, we perform the inexpensive checks
+    // on m_node to see if it necessitates emitting a character first and will early return 
+    // before encountering shouldRepresentNodeOffsetZero()s worse case behavior.
+    if (shouldEmitTabBeforeNode(m_node)) {
+        if (shouldRepresentNodeOffsetZero())
+            emitCharacter('\t', m_node->parentNode(), m_node, 0, 0);
+    } else if (shouldEmitNewlineBeforeNode(m_node)) {
+        if (shouldRepresentNodeOffsetZero())
+            emitCharacter('\n', m_node->parentNode(), m_node, 0, 0);
+    } else if (shouldEmitSpaceBeforeAndAfterNode(m_node)) {
+        if (shouldRepresentNodeOffsetZero())
+            emitCharacter(' ', m_node->parentNode(), m_node, 0, 0);
+    }
+}
+
+bool TextIterator::handleNonTextNode()
+{
+    if (shouldEmitNewlineForNode(m_node))
+        emitCharacter('\n', m_node->parentNode(), m_node, 0, 1);
+    else if (m_emitsCharactersBetweenAllVisiblePositions && m_node->renderer() && m_node->renderer()->isHR())
+        emitCharacter(' ', m_node->parentNode(), m_node, 0, 1);
+    else
+        representNodeOffsetZero();
+
+    return true;
+}
+
+void TextIterator::exitNode()
+{
+    // prevent emitting a newline when exiting a collapsed block at beginning of the range
+    // FIXME: !m_hasEmitted does not necessarily mean there was a collapsed block... it could
+    // have been an hr (e.g.). Also, a collapsed block could have height (e.g. a table) and
+    // therefore look like a blank line.
+    if (!m_hasEmitted)
+        return;
+        
+    // Emit with a position *inside* m_node, after m_node's contents, in 
+    // case it is a block, because the run should start where the 
+    // emitted character is positioned visually.
+    Node* baseNode = m_node->lastChild() ? m_node->lastChild() : m_node;
+    // FIXME: This shouldn't require the m_lastTextNode to be true, but we can't change that without making
+    // the logic in _web_attributedStringFromRange match.  We'll get that for free when we switch to use
+    // TextIterator in _web_attributedStringFromRange.
+    // See <rdar://problem/5428427> for an example of how this mismatch will cause problems.
+    if (m_lastTextNode && shouldEmitNewlineAfterNode(m_node)) {
+        // use extra newline to represent margin bottom, as needed
+        bool addNewline = shouldEmitExtraNewlineForNode(m_node);
+        
+        // FIXME: We need to emit a '\n' as we leave an empty block(s) that
+        // contain a VisiblePosition when doing selection preservation.
+        if (m_lastCharacter != '\n') {
+            // insert a newline with a position following this block's contents.
+            emitCharacter('\n', baseNode->parentNode(), baseNode, 1, 1);
+            // remember whether to later add a newline for the current node
+            ASSERT(!m_needsAnotherNewline);
+            m_needsAnotherNewline = addNewline;
+        } else if (addNewline)
+            // insert a newline with a position following this block's contents.
+            emitCharacter('\n', baseNode->parentNode(), baseNode, 1, 1);
+    }
+    
+    // If nothing was emitted, see if we need to emit a space.
+    if (!m_positionNode && shouldEmitSpaceBeforeAndAfterNode(m_node))
+        emitCharacter(' ', baseNode->parentNode(), baseNode, 1, 1);
+}
+
+void TextIterator::emitCharacter(UChar c, Node* textNode, Node* offsetBaseNode, int textStartOffset, int textEndOffset)
+{
+    m_hasEmitted = true;
+    
+    // remember information with which to construct the TextIterator::range()
+    // NOTE: textNode is often not a text node, so the range will specify child nodes of positionNode
+    m_positionNode = textNode;
+    m_positionOffsetBaseNode = offsetBaseNode;
+    m_positionStartOffset = textStartOffset;
+    m_positionEndOffset = textEndOffset;
+ 
+    // remember information with which to construct the TextIterator::characters() and length()
+    m_singleCharacterBuffer = c;
+    m_textCharacters = &m_singleCharacterBuffer;
+    m_textLength = 1;
+
+    // remember some iteration state
+    m_lastTextNodeEndedWithCollapsedSpace = false;
+    m_lastCharacter = c;
+}
+
+void TextIterator::emitText(Node* textNode, RenderObject* renderObject, int textStartOffset, int textEndOffset)
+{
+    RenderText* renderer = toRenderText(renderObject);
+    m_text = m_emitsTextWithoutTranscoding ? renderer->textWithoutTranscoding() : renderer->text();
+    ASSERT(m_text.characters());
+
+    m_positionNode = textNode;
+    m_positionOffsetBaseNode = 0;
+    m_positionStartOffset = textStartOffset;
+    m_positionEndOffset = textEndOffset;
+    m_textCharacters = m_text.characters() + textStartOffset;
+    m_textLength = textEndOffset - textStartOffset;
+    m_lastCharacter = m_text[textEndOffset - 1];
+
+    m_lastTextNodeEndedWithCollapsedSpace = false;
+    m_hasEmitted = true;
+}
+
+void TextIterator::emitText(Node* textNode, int textStartOffset, int textEndOffset)
+{
+    emitText(textNode, m_node->renderer(), textStartOffset, textEndOffset);
+}
+
+PassRefPtr<Range> TextIterator::range() const
+{
+    // use the current run information, if we have it
+    if (m_positionNode) {
+        if (m_positionOffsetBaseNode) {
+            int index = m_positionOffsetBaseNode->nodeIndex();
+            m_positionStartOffset += index;
+            m_positionEndOffset += index;
+            m_positionOffsetBaseNode = 0;
+        }
+        return Range::create(m_positionNode->document(), m_positionNode, m_positionStartOffset, m_positionNode, m_positionEndOffset);
+    }
+
+    // otherwise, return the end of the overall range we were given
+    if (m_endContainer)
+        return Range::create(m_endContainer->document(), m_endContainer, m_endOffset, m_endContainer, m_endOffset);
+        
+    return 0;
+}
+    
+Node* TextIterator::node() const
+{
+    RefPtr<Range> textRange = range();
+    if (!textRange)
+        return 0;
+
+    Node* node = textRange->startContainer();
+    if (!node)
+        return 0;
+    if (node->offsetInCharacters())
+        return node;
+    
+    return node->childNode(textRange->startOffset());
+}
+
+// --------
+
+SimplifiedBackwardsTextIterator::SimplifiedBackwardsTextIterator()
+    : m_behavior(TextIteratorDefaultBehavior)
+    , m_node(0)
+    , m_positionNode(0)
+{
+}
+
+SimplifiedBackwardsTextIterator::SimplifiedBackwardsTextIterator(const Range* r, TextIteratorBehavior behavior)
+    : m_behavior(behavior)
+    , m_node(0)
+    , m_positionNode(0)
+{
+    ASSERT(m_behavior == TextIteratorDefaultBehavior || m_behavior == TextIteratorEndsAtEditingBoundary);
+
+    if (!r)
+        return;
+
+    Node* startNode = r->startContainer();
+    if (!startNode)
+        return;
+    Node* endNode = r->endContainer();
+    int startOffset = r->startOffset();
+    int endOffset = r->endOffset();
+
+    if (!startNode->offsetInCharacters()) {
+        if (startOffset >= 0 && startOffset < static_cast<int>(startNode->childNodeCount())) {
+            startNode = startNode->childNode(startOffset);
+            startOffset = 0;
+        }
+    }
+    if (!endNode->offsetInCharacters()) {
+        if (endOffset > 0 && endOffset <= static_cast<int>(endNode->childNodeCount())) {
+            endNode = endNode->childNode(endOffset - 1);
+            endOffset = lastOffsetInNode(endNode);
+        }
+    }
+
+    setCurrentNode(endNode);
+    setUpFullyClippedStack(m_fullyClippedStack, m_node);    
+    m_offset = endOffset;
+    m_handledNode = false;
+    m_handledChildren = endOffset == 0;
+
+    m_startNode = startNode;
+    m_startOffset = startOffset;
+    m_endNode = endNode;
+    m_endOffset = endOffset;
+    
+#ifndef NDEBUG
+    // Need this just because of the assert.
+    m_positionNode = endNode;
+#endif
+
+    m_lastTextNode = 0;
+    m_lastCharacter = '\n';
+
+    m_pastStartNode = previousInPostOrderCrossingShadowBoundaries(startNode, startOffset);
+
+    advance();
+}
+
+void SimplifiedBackwardsTextIterator::advance()
+{
+    ASSERT(m_positionNode);
+
+    m_positionNode = 0;
+    m_textLength = 0;
+
+    while (m_node && m_node != m_pastStartNode) {
+        // Don't handle node if we start iterating at [node, 0].
+        if (!m_handledNode && !(m_node == m_endNode && m_endOffset == 0)) {
+            RenderObject* renderer = m_node->renderer();
+            if (renderer && renderer->isText() && m_node->nodeType() == Node::TEXT_NODE) {
+                // FIXME: What about CDATA_SECTION_NODE?
+                if (renderer->style()->visibility() == VISIBLE && m_offset > 0)
+                    m_handledNode = handleTextNode();
+            } else if (renderer && (renderer->isImage() || renderer->isWidget())) {
+                if (renderer->style()->visibility() == VISIBLE && m_offset > 0)
+                    m_handledNode = handleReplacedElement();
+            } else
+                m_handledNode = handleNonTextNode();
+            if (m_positionNode)
+                return;
+        }
+
+        Node* next = m_handledChildren ? 0 : m_node->lastChild();
+        if (!next) {
+            // Exit empty containers as we pass over them or containers
+            // where [container, 0] is where we started iterating.
+            if (!m_handledNode &&
+                canHaveChildrenForEditing(m_node) && 
+                m_node->parentNode() && 
+                (!m_node->lastChild() || (m_node == m_endNode && m_endOffset == 0))) {
+                exitNode();
+                if (m_positionNode) {
+                    m_handledNode = true;
+                    m_handledChildren = true;
+                    return;
+                }            
+            }
+            // Exit all other containers.
+            while (!m_node->previousSibling()) {
+                if (!setCurrentNode(m_node->parentOrHostNode()))
+                    break;
+                m_fullyClippedStack.pop();
+                exitNode();
+                if (m_positionNode) {
+                    m_handledNode = true;
+                    m_handledChildren = true;
+                    return;
+                }
+            }
+
+            next = m_node->previousSibling();
+            m_fullyClippedStack.pop();
+        }
+        
+        if (m_node && setCurrentNode(next))
+            pushFullyClippedState(m_fullyClippedStack, m_node);
+        else
+            clearCurrentNode();
+
+        // For the purpose of word boundary detection,
+        // we should iterate all visible text and trailing (collapsed) whitespaces. 
+        m_offset = m_node ? maxOffsetIncludingCollapsedSpaces(m_node) : 0;
+        m_handledNode = false;
+        m_handledChildren = false;
+        
+        if (m_positionNode)
+            return;
+    }
+}
+
+bool SimplifiedBackwardsTextIterator::handleTextNode()
+{
+    m_lastTextNode = m_node;
+
+    RenderText* renderer = toRenderText(m_node->renderer());
+    String str = renderer->text();
+
+    if (!renderer->firstTextBox() && str.length() > 0)
+        return true;
+
+    m_positionEndOffset = m_offset;
+
+    m_offset = (m_node == m_startNode) ? m_startOffset : 0;
+    m_positionNode = m_node;
+    m_positionStartOffset = m_offset;
+    m_textLength = m_positionEndOffset - m_positionStartOffset;
+    m_textCharacters = str.characters() + m_positionStartOffset;
+
+    m_lastCharacter = str[m_positionEndOffset - 1];
+
+    return true;
+}
+
+bool SimplifiedBackwardsTextIterator::handleReplacedElement()
+{
+    unsigned index = m_node->nodeIndex();
+    // We want replaced elements to behave like punctuation for boundary 
+    // finding, and to simply take up space for the selection preservation 
+    // code in moveParagraphs, so we use a comma.  Unconditionally emit
+    // here because this iterator is only used for boundary finding.
+    emitCharacter(',', m_node->parentNode(), index, index + 1);
+    return true;
+}
+
+bool SimplifiedBackwardsTextIterator::handleNonTextNode()
+{    
+    // We can use a linefeed in place of a tab because this simple iterator is only used to
+    // find boundaries, not actual content.  A linefeed breaks words, sentences, and paragraphs.
+    if (shouldEmitNewlineForNode(m_node) || shouldEmitNewlineAfterNode(m_node) || shouldEmitTabBeforeNode(m_node)) {
+        unsigned index = m_node->nodeIndex();
+        // The start of this emitted range is wrong. Ensuring correctness would require
+        // VisiblePositions and so would be slow. previousBoundary expects this.
+        emitCharacter('\n', m_node->parentNode(), index + 1, index + 1);
+    }
+    return true;
+}
+
+void SimplifiedBackwardsTextIterator::exitNode()
+{
+    if (shouldEmitNewlineForNode(m_node) || shouldEmitNewlineBeforeNode(m_node) || shouldEmitTabBeforeNode(m_node)) {
+        // The start of this emitted range is wrong. Ensuring correctness would require
+        // VisiblePositions and so would be slow. previousBoundary expects this.
+        emitCharacter('\n', m_node, 0, 0);
+    }
+}
+
+void SimplifiedBackwardsTextIterator::emitCharacter(UChar c, Node* node, int startOffset, int endOffset)
+{
+    m_singleCharacterBuffer = c;
+    m_positionNode = node;
+    m_positionStartOffset = startOffset;
+    m_positionEndOffset = endOffset;
+    m_textCharacters = &m_singleCharacterBuffer;
+    m_textLength = 1;
+    m_lastCharacter = c;
+}
+
+bool SimplifiedBackwardsTextIterator::crossesEditingBoundary(Node* node) const
+{
+    return m_node && m_node->isContentEditable() != node->isContentEditable();
+}
+
+bool SimplifiedBackwardsTextIterator::setCurrentNode(Node* node)
+{
+    if (!node)
+        return false;
+    if (m_behavior == TextIteratorEndsAtEditingBoundary && crossesEditingBoundary(node))
+        return false;
+    m_node = node;
+    return true;
+}
+
+void SimplifiedBackwardsTextIterator::clearCurrentNode()
+{
+    m_node = 0;
+}
+
+PassRefPtr<Range> SimplifiedBackwardsTextIterator::range() const
+{
+    if (m_positionNode)
+        return Range::create(m_positionNode->document(), m_positionNode, m_positionStartOffset, m_positionNode, m_positionEndOffset);
+    
+    return Range::create(m_startNode->document(), m_startNode, m_startOffset, m_startNode, m_startOffset);
+}
+
+// --------
+
+CharacterIterator::CharacterIterator()
+    : m_offset(0)
+    , m_runOffset(0)
+    , m_atBreak(true)
+{
+}
+
+CharacterIterator::CharacterIterator(const Range* r, TextIteratorBehavior behavior)
+    : m_offset(0)
+    , m_runOffset(0)
+    , m_atBreak(true)
+    , m_textIterator(r, behavior)
+{
+    while (!atEnd() && m_textIterator.length() == 0)
+        m_textIterator.advance();
+}
+
+PassRefPtr<Range> CharacterIterator::range() const
+{
+    RefPtr<Range> r = m_textIterator.range();
+    if (!m_textIterator.atEnd()) {
+        if (m_textIterator.length() <= 1) {
+            ASSERT(m_runOffset == 0);
+        } else {
+            Node* n = r->startContainer();
+            ASSERT(n == r->endContainer());
+            int offset = r->startOffset() + m_runOffset;
+            ExceptionCode ec = 0;
+            r->setStart(n, offset, ec);
+            r->setEnd(n, offset + 1, ec);
+            ASSERT(!ec);
+        }
+    }
+    return r.release();
+}
+
+void CharacterIterator::advance(int count)
+{
+    if (count <= 0) {
+        ASSERT(count == 0);
+        return;
+    }
+    
+    m_atBreak = false;
+
+    // easy if there is enough left in the current m_textIterator run
+    int remaining = m_textIterator.length() - m_runOffset;
+    if (count < remaining) {
+        m_runOffset += count;
+        m_offset += count;
+        return;
+    }
+
+    // exhaust the current m_textIterator run
+    count -= remaining;
+    m_offset += remaining;
+    
+    // move to a subsequent m_textIterator run
+    for (m_textIterator.advance(); !atEnd(); m_textIterator.advance()) {
+        int runLength = m_textIterator.length();
+        if (runLength == 0)
+            m_atBreak = true;
+        else {
+            // see whether this is m_textIterator to use
+            if (count < runLength) {
+                m_runOffset = count;
+                m_offset += count;
+                return;
+            }
+            
+            // exhaust this m_textIterator run
+            count -= runLength;
+            m_offset += runLength;
+        }
+    }
+
+    // ran to the end of the m_textIterator... no more runs left
+    m_atBreak = true;
+    m_runOffset = 0;
+}
+
+String CharacterIterator::string(int numChars)
+{
+    Vector<UChar> result;
+    result.reserveInitialCapacity(numChars);
+    while (numChars > 0 && !atEnd()) {
+        int runSize = min(numChars, length());
+        result.append(characters(), runSize);
+        numChars -= runSize;
+        advance(runSize);
+    }
+    return String::adopt(result);
+}
+
+static PassRefPtr<Range> characterSubrange(CharacterIterator& it, int offset, int length)
+{
+    it.advance(offset);
+    RefPtr<Range> start = it.range();
+
+    if (length > 1)
+        it.advance(length - 1);
+    RefPtr<Range> end = it.range();
+
+    return Range::create(start->startContainer()->document(), 
+        start->startContainer(), start->startOffset(), 
+        end->endContainer(), end->endOffset());
+}
+
+BackwardsCharacterIterator::BackwardsCharacterIterator()
+    : m_offset(0)
+    , m_runOffset(0)
+    , m_atBreak(true)
+{
+}
+
+BackwardsCharacterIterator::BackwardsCharacterIterator(const Range* range, TextIteratorBehavior behavior)
+    : m_offset(0)
+    , m_runOffset(0)
+    , m_atBreak(true)
+    , m_textIterator(range, behavior)
+{
+    while (!atEnd() && !m_textIterator.length())
+        m_textIterator.advance();
+}
+
+PassRefPtr<Range> BackwardsCharacterIterator::range() const
+{
+    RefPtr<Range> r = m_textIterator.range();
+    if (!m_textIterator.atEnd()) {
+        if (m_textIterator.length() <= 1)
+            ASSERT(m_runOffset == 0);
+        else {
+            Node* n = r->startContainer();
+            ASSERT(n == r->endContainer());
+            int offset = r->endOffset() - m_runOffset;
+            ExceptionCode ec = 0;
+            r->setStart(n, offset - 1, ec);
+            r->setEnd(n, offset, ec);
+            ASSERT(!ec);
+        }
+    }
+    return r.release();
+}
+
+void BackwardsCharacterIterator::advance(int count)
+{
+    if (count <= 0) {
+        ASSERT(!count);
+        return;
+    }
+
+    m_atBreak = false;
+
+    int remaining = m_textIterator.length() - m_runOffset;
+    if (count < remaining) {
+        m_runOffset += count;
+        m_offset += count;
+        return;
+    }
+
+    count -= remaining;
+    m_offset += remaining;
+
+    for (m_textIterator.advance(); !atEnd(); m_textIterator.advance()) {
+        int runLength = m_textIterator.length();
+        if (runLength == 0)
+            m_atBreak = true;
+        else {
+            if (count < runLength) {
+                m_runOffset = count;
+                m_offset += count;
+                return;
+            }
+            
+            count -= runLength;
+            m_offset += runLength;
+        }
+    }
+
+    m_atBreak = true;
+    m_runOffset = 0;
+}
+
+// --------
+
+WordAwareIterator::WordAwareIterator()
+    : m_previousText(0)
+    , m_didLookAhead(false)
+{
+}
+
+WordAwareIterator::WordAwareIterator(const Range* r)
+    : m_previousText(0)
+    , m_didLookAhead(true) // so we consider the first chunk from the text iterator
+    , m_textIterator(r)
+{
+    advance(); // get in position over the first chunk of text
+}
+
+WordAwareIterator::~WordAwareIterator()
+{
+}
+
+// We're always in one of these modes:
+// - The current chunk in the text iterator is our current chunk
+//      (typically its a piece of whitespace, or text that ended with whitespace)
+// - The previous chunk in the text iterator is our current chunk
+//      (we looked ahead to the next chunk and found a word boundary)
+// - We built up our own chunk of text from many chunks from the text iterator
+
+// FIXME: Performance could be bad for huge spans next to each other that don't fall on word boundaries.
+
+void WordAwareIterator::advance()
+{
+    m_previousText = 0;
+    m_buffer.clear();      // toss any old buffer we built up
+
+    // If last time we did a look-ahead, start with that looked-ahead chunk now
+    if (!m_didLookAhead) {
+        ASSERT(!m_textIterator.atEnd());
+        m_textIterator.advance();
+    }
+    m_didLookAhead = false;
+
+    // Go to next non-empty chunk 
+    while (!m_textIterator.atEnd() && m_textIterator.length() == 0)
+        m_textIterator.advance();
+    m_range = m_textIterator.range();
+
+    if (m_textIterator.atEnd())
+        return;
+    
+    while (1) {
+        // If this chunk ends in whitespace we can just use it as our chunk.
+        if (isSpaceOrNewline(m_textIterator.characters()[m_textIterator.length() - 1]))
+            return;
+
+        // If this is the first chunk that failed, save it in previousText before look ahead
+        if (m_buffer.isEmpty()) {
+            m_previousText = m_textIterator.characters();
+            m_previousLength = m_textIterator.length();
+        }
+
+        // Look ahead to next chunk.  If it is whitespace or a break, we can use the previous stuff
+        m_textIterator.advance();
+        if (m_textIterator.atEnd() || m_textIterator.length() == 0 || isSpaceOrNewline(m_textIterator.characters()[0])) {
+            m_didLookAhead = true;
+            return;
+        }
+
+        if (m_buffer.isEmpty()) {
+            // Start gobbling chunks until we get to a suitable stopping point
+            m_buffer.append(m_previousText, m_previousLength);
+            m_previousText = 0;
+        }
+        m_buffer.append(m_textIterator.characters(), m_textIterator.length());
+        int exception = 0;
+        m_range->setEnd(m_textIterator.range()->endContainer(), m_textIterator.range()->endOffset(), exception);
+    }
+}
+
+int WordAwareIterator::length() const
+{
+    if (!m_buffer.isEmpty())
+        return m_buffer.size();
+    if (m_previousText)
+        return m_previousLength;
+    return m_textIterator.length();
+}
+
+const UChar* WordAwareIterator::characters() const
+{
+    if (!m_buffer.isEmpty())
+        return m_buffer.data();
+    if (m_previousText)
+        return m_previousText;
+    return m_textIterator.characters();
+}
+
+// --------
+
+static inline UChar foldQuoteMarkOrSoftHyphen(UChar c)
+{
+    switch (c) {
+        case hebrewPunctuationGershayim:
+        case leftDoubleQuotationMark:
+        case rightDoubleQuotationMark:
+            return '"';
+        case hebrewPunctuationGeresh:
+        case leftSingleQuotationMark:
+        case rightSingleQuotationMark:
+            return '\'';
+        case softHyphen:
+            // Replace soft hyphen with an ignorable character so that their presence or absence will
+            // not affect string comparison.
+            return 0;
+        default:
+            return c;
+    }
+}
+
+static inline void foldQuoteMarksAndSoftHyphens(String& s)
+{
+    s.replace(hebrewPunctuationGeresh, '\'');
+    s.replace(hebrewPunctuationGershayim, '"');
+    s.replace(leftDoubleQuotationMark, '"');
+    s.replace(leftSingleQuotationMark, '\'');
+    s.replace(rightDoubleQuotationMark, '"');
+    s.replace(rightSingleQuotationMark, '\'');
+    // Replace soft hyphen with an ignorable character so that their presence or absence will
+    // not affect string comparison.
+    s.replace(softHyphen, 0);
+}
+
+#if USE(ICU_UNICODE) && !UCONFIG_NO_COLLATION
+
+static inline void foldQuoteMarksAndSoftHyphens(UChar* data, size_t length)
+{
+    for (size_t i = 0; i < length; ++i)
+        data[i] = foldQuoteMarkOrSoftHyphen(data[i]);
+}
+
+static const size_t minimumSearchBufferSize = 8192;
+
+#ifndef NDEBUG
+static bool searcherInUse;
+#endif
+
+static UStringSearch* createSearcher()
+{
+    // Provide a non-empty pattern and non-empty text so usearch_open will not fail,
+    // but it doesn't matter exactly what it is, since we don't perform any searches
+    // without setting both the pattern and the text.
+    UErrorCode status = U_ZERO_ERROR;
+    UStringSearch* searcher = usearch_open(&newlineCharacter, 1, &newlineCharacter, 1, currentSearchLocaleID(), 0, &status);
+    ASSERT(status == U_ZERO_ERROR || status == U_USING_FALLBACK_WARNING || status == U_USING_DEFAULT_WARNING);
+    return searcher;
+}
+
+static UStringSearch* searcher()
+{
+    static UStringSearch* searcher = createSearcher();
+    return searcher;
+}
+
+static inline void lockSearcher()
+{
+#ifndef NDEBUG
+    ASSERT(!searcherInUse);
+    searcherInUse = true;
+#endif
+}
+
+static inline void unlockSearcher()
+{
+#ifndef NDEBUG
+    ASSERT(searcherInUse);
+    searcherInUse = false;
+#endif
+}
+
+// ICU's search ignores the distinction between small kana letters and ones
+// that are not small, and also characters that differ only in the voicing
+// marks when considering only primary collation strength diffrences.
+// This is not helpful for end users, since these differences make words
+// distinct, so for our purposes we need these to be considered.
+// The Unicode folks do not think the collation algorithm should be
+// changed. To work around this, we would like to tailor the ICU searcher,
+// but we can't get that to work yet. So instead, we check for cases where
+// these differences occur, and skip those matches.
+
+// We refer to the above technique as the "kana workaround". The next few
+// functions are helper functinos for the kana workaround.
+
+static inline bool isKanaLetter(UChar character)
+{
+    // Hiragana letters.
+    if (character >= 0x3041 && character <= 0x3096)
+        return true;
+
+    // Katakana letters.
+    if (character >= 0x30A1 && character <= 0x30FA)
+        return true;
+    if (character >= 0x31F0 && character <= 0x31FF)
+        return true;
+
+    // Halfwidth katakana letters.
+    if (character >= 0xFF66 && character <= 0xFF9D && character != 0xFF70)
+        return true;
+
+    return false;
+}
+
+static inline bool isSmallKanaLetter(UChar character)
+{
+    ASSERT(isKanaLetter(character));
+
+    switch (character) {
+    case 0x3041: // HIRAGANA LETTER SMALL A
+    case 0x3043: // HIRAGANA LETTER SMALL I
+    case 0x3045: // HIRAGANA LETTER SMALL U
+    case 0x3047: // HIRAGANA LETTER SMALL E
+    case 0x3049: // HIRAGANA LETTER SMALL O
+    case 0x3063: // HIRAGANA LETTER SMALL TU
+    case 0x3083: // HIRAGANA LETTER SMALL YA
+    case 0x3085: // HIRAGANA LETTER SMALL YU
+    case 0x3087: // HIRAGANA LETTER SMALL YO
+    case 0x308E: // HIRAGANA LETTER SMALL WA
+    case 0x3095: // HIRAGANA LETTER SMALL KA
+    case 0x3096: // HIRAGANA LETTER SMALL KE
+    case 0x30A1: // KATAKANA LETTER SMALL A
+    case 0x30A3: // KATAKANA LETTER SMALL I
+    case 0x30A5: // KATAKANA LETTER SMALL U
+    case 0x30A7: // KATAKANA LETTER SMALL E
+    case 0x30A9: // KATAKANA LETTER SMALL O
+    case 0x30C3: // KATAKANA LETTER SMALL TU
+    case 0x30E3: // KATAKANA LETTER SMALL YA
+    case 0x30E5: // KATAKANA LETTER SMALL YU
+    case 0x30E7: // KATAKANA LETTER SMALL YO
+    case 0x30EE: // KATAKANA LETTER SMALL WA
+    case 0x30F5: // KATAKANA LETTER SMALL KA
+    case 0x30F6: // KATAKANA LETTER SMALL KE
+    case 0x31F0: // KATAKANA LETTER SMALL KU
+    case 0x31F1: // KATAKANA LETTER SMALL SI
+    case 0x31F2: // KATAKANA LETTER SMALL SU
+    case 0x31F3: // KATAKANA LETTER SMALL TO
+    case 0x31F4: // KATAKANA LETTER SMALL NU
+    case 0x31F5: // KATAKANA LETTER SMALL HA
+    case 0x31F6: // KATAKANA LETTER SMALL HI
+    case 0x31F7: // KATAKANA LETTER SMALL HU
+    case 0x31F8: // KATAKANA LETTER SMALL HE
+    case 0x31F9: // KATAKANA LETTER SMALL HO
+    case 0x31FA: // KATAKANA LETTER SMALL MU
+    case 0x31FB: // KATAKANA LETTER SMALL RA
+    case 0x31FC: // KATAKANA LETTER SMALL RI
+    case 0x31FD: // KATAKANA LETTER SMALL RU
+    case 0x31FE: // KATAKANA LETTER SMALL RE
+    case 0x31FF: // KATAKANA LETTER SMALL RO
+    case 0xFF67: // HALFWIDTH KATAKANA LETTER SMALL A
+    case 0xFF68: // HALFWIDTH KATAKANA LETTER SMALL I
+    case 0xFF69: // HALFWIDTH KATAKANA LETTER SMALL U
+    case 0xFF6A: // HALFWIDTH KATAKANA LETTER SMALL E
+    case 0xFF6B: // HALFWIDTH KATAKANA LETTER SMALL O
+    case 0xFF6C: // HALFWIDTH KATAKANA LETTER SMALL YA
+    case 0xFF6D: // HALFWIDTH KATAKANA LETTER SMALL YU
+    case 0xFF6E: // HALFWIDTH KATAKANA LETTER SMALL YO
+    case 0xFF6F: // HALFWIDTH KATAKANA LETTER SMALL TU
+        return true;
+    }
+    return false;
+}
+
+enum VoicedSoundMarkType { NoVoicedSoundMark, VoicedSoundMark, SemiVoicedSoundMark };
+
+static inline VoicedSoundMarkType composedVoicedSoundMark(UChar character)
+{
+    ASSERT(isKanaLetter(character));
+
+    switch (character) {
+    case 0x304C: // HIRAGANA LETTER GA
+    case 0x304E: // HIRAGANA LETTER GI
+    case 0x3050: // HIRAGANA LETTER GU
+    case 0x3052: // HIRAGANA LETTER GE
+    case 0x3054: // HIRAGANA LETTER GO
+    case 0x3056: // HIRAGANA LETTER ZA
+    case 0x3058: // HIRAGANA LETTER ZI
+    case 0x305A: // HIRAGANA LETTER ZU
+    case 0x305C: // HIRAGANA LETTER ZE
+    case 0x305E: // HIRAGANA LETTER ZO
+    case 0x3060: // HIRAGANA LETTER DA
+    case 0x3062: // HIRAGANA LETTER DI
+    case 0x3065: // HIRAGANA LETTER DU
+    case 0x3067: // HIRAGANA LETTER DE
+    case 0x3069: // HIRAGANA LETTER DO
+    case 0x3070: // HIRAGANA LETTER BA
+    case 0x3073: // HIRAGANA LETTER BI
+    case 0x3076: // HIRAGANA LETTER BU
+    case 0x3079: // HIRAGANA LETTER BE
+    case 0x307C: // HIRAGANA LETTER BO
+    case 0x3094: // HIRAGANA LETTER VU
+    case 0x30AC: // KATAKANA LETTER GA
+    case 0x30AE: // KATAKANA LETTER GI
+    case 0x30B0: // KATAKANA LETTER GU
+    case 0x30B2: // KATAKANA LETTER GE
+    case 0x30B4: // KATAKANA LETTER GO
+    case 0x30B6: // KATAKANA LETTER ZA
+    case 0x30B8: // KATAKANA LETTER ZI
+    case 0x30BA: // KATAKANA LETTER ZU
+    case 0x30BC: // KATAKANA LETTER ZE
+    case 0x30BE: // KATAKANA LETTER ZO
+    case 0x30C0: // KATAKANA LETTER DA
+    case 0x30C2: // KATAKANA LETTER DI
+    case 0x30C5: // KATAKANA LETTER DU
+    case 0x30C7: // KATAKANA LETTER DE
+    case 0x30C9: // KATAKANA LETTER DO
+    case 0x30D0: // KATAKANA LETTER BA
+    case 0x30D3: // KATAKANA LETTER BI
+    case 0x30D6: // KATAKANA LETTER BU
+    case 0x30D9: // KATAKANA LETTER BE
+    case 0x30DC: // KATAKANA LETTER BO
+    case 0x30F4: // KATAKANA LETTER VU
+    case 0x30F7: // KATAKANA LETTER VA
+    case 0x30F8: // KATAKANA LETTER VI
+    case 0x30F9: // KATAKANA LETTER VE
+    case 0x30FA: // KATAKANA LETTER VO
+        return VoicedSoundMark;
+    case 0x3071: // HIRAGANA LETTER PA
+    case 0x3074: // HIRAGANA LETTER PI
+    case 0x3077: // HIRAGANA LETTER PU
+    case 0x307A: // HIRAGANA LETTER PE
+    case 0x307D: // HIRAGANA LETTER PO
+    case 0x30D1: // KATAKANA LETTER PA
+    case 0x30D4: // KATAKANA LETTER PI
+    case 0x30D7: // KATAKANA LETTER PU
+    case 0x30DA: // KATAKANA LETTER PE
+    case 0x30DD: // KATAKANA LETTER PO
+        return SemiVoicedSoundMark;
+    }
+    return NoVoicedSoundMark;
+}
+
+static inline bool isCombiningVoicedSoundMark(UChar character)
+{
+    switch (character) {
+    case 0x3099: // COMBINING KATAKANA-HIRAGANA VOICED SOUND MARK
+    case 0x309A: // COMBINING KATAKANA-HIRAGANA SEMI-VOICED SOUND MARK
+        return true;
+    }
+    return false;
+}
+
+static inline bool containsKanaLetters(const String& pattern)
+{
+    const UChar* characters = pattern.characters();
+    unsigned length = pattern.length();
+    for (unsigned i = 0; i < length; ++i) {
+        if (isKanaLetter(characters[i]))
+            return true;
+    }
+    return false;
+}
+
+static void normalizeCharacters(const UChar* characters, unsigned length, Vector<UChar>& buffer)
+{
+    ASSERT(length);
+
+    buffer.resize(length);
+
+    UErrorCode status = U_ZERO_ERROR;
+    size_t bufferSize = unorm_normalize(characters, length, UNORM_NFC, 0, buffer.data(), length, &status);
+    ASSERT(status == U_ZERO_ERROR || status == U_STRING_NOT_TERMINATED_WARNING || status == U_BUFFER_OVERFLOW_ERROR);
+    ASSERT(bufferSize);
+
+    buffer.resize(bufferSize);
+
+    if (status == U_ZERO_ERROR || status == U_STRING_NOT_TERMINATED_WARNING)
+        return;
+
+    status = U_ZERO_ERROR;
+    unorm_normalize(characters, length, UNORM_NFC, 0, buffer.data(), bufferSize, &status);
+    ASSERT(status == U_STRING_NOT_TERMINATED_WARNING);
+}
+
+static bool isNonLatin1Separator(UChar32 character)
+{
+    ASSERT_ARG(character, character >= 256);
+
+    return U_GET_GC_MASK(character) & (U_GC_S_MASK | U_GC_P_MASK | U_GC_Z_MASK | U_GC_CF_MASK);
+}
+
+static inline bool isSeparator(UChar32 character)
+{
+    static const bool latin1SeparatorTable[256] = {
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // space ! " # $ % & ' ( ) * + , - . /
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, //                         : ; < = > ?
+        1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //   @
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, //                         [ \ ] ^ _
+        1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //   `
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, //                           { | } ~
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1,
+        1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0
+    };
+
+    if (character < 256)
+        return latin1SeparatorTable[character];
+
+    return isNonLatin1Separator(character);
+}
+
+inline SearchBuffer::SearchBuffer(const String& target, FindOptions options)
+    : m_target(target)
+    , m_options(options)
+    , m_prefixLength(0)
+    , m_atBreak(true)
+    , m_needsMoreContext(options & AtWordStarts)
+    , m_targetRequiresKanaWorkaround(containsKanaLetters(m_target))
+{
+    ASSERT(!m_target.isEmpty());
+
+    // FIXME: We'd like to tailor the searcher to fold quote marks for us instead
+    // of doing it in a separate replacement pass here, but ICU doesn't offer a way
+    // to add tailoring on top of the locale-specific tailoring as of this writing.
+    foldQuoteMarksAndSoftHyphens(m_target);
+
+    size_t targetLength = m_target.length();
+    m_buffer.reserveInitialCapacity(max(targetLength * 8, minimumSearchBufferSize));
+    m_overlap = m_buffer.capacity() / 4;
+
+    if ((m_options & AtWordStarts) && targetLength) {
+        UChar32 targetFirstCharacter;
+        U16_GET(m_target.characters(), 0, 0, targetLength, targetFirstCharacter);
+        // Characters in the separator category never really occur at the beginning of a word,
+        // so if the target begins with such a character, we just ignore the AtWordStart option.
+        if (isSeparator(targetFirstCharacter)) {
+            m_options &= ~AtWordStarts;
+            m_needsMoreContext = false;
+        }
+    }
+
+    // Grab the single global searcher.
+    // If we ever have a reason to do more than once search buffer at once, we'll have
+    // to move to multiple searchers.
+    lockSearcher();
+
+    UStringSearch* searcher = WebCore::searcher();
+    UCollator* collator = usearch_getCollator(searcher);
+
+    UCollationStrength strength = m_options & CaseInsensitive ? UCOL_PRIMARY : UCOL_TERTIARY;
+    if (ucol_getStrength(collator) != strength) {
+        ucol_setStrength(collator, strength);
+        usearch_reset(searcher);
+    }
+
+    UErrorCode status = U_ZERO_ERROR;
+    usearch_setPattern(searcher, m_target.characters(), targetLength, &status);
+    ASSERT(status == U_ZERO_ERROR);
+
+    // The kana workaround requires a normalized copy of the target string.
+    if (m_targetRequiresKanaWorkaround)
+        normalizeCharacters(m_target.characters(), m_target.length(), m_normalizedTarget);
+}
+
+inline SearchBuffer::~SearchBuffer()
+{
+    unlockSearcher();
+}
+
+inline size_t SearchBuffer::append(const UChar* characters, size_t length)
+{
+    ASSERT(length);
+
+    if (m_atBreak) {
+        m_buffer.shrink(0);
+        m_prefixLength = 0;
+        m_atBreak = false;
+    } else if (m_buffer.size() == m_buffer.capacity()) {
+        memcpy(m_buffer.data(), m_buffer.data() + m_buffer.size() - m_overlap, m_overlap * sizeof(UChar));
+        m_prefixLength -= min(m_prefixLength, m_buffer.size() - m_overlap);
+        m_buffer.shrink(m_overlap);
+    }
+
+    size_t oldLength = m_buffer.size();
+    size_t usableLength = min(m_buffer.capacity() - oldLength, length);
+    ASSERT(usableLength);
+    m_buffer.append(characters, usableLength);
+    foldQuoteMarksAndSoftHyphens(m_buffer.data() + oldLength, usableLength);
+    return usableLength;
+}
+
+inline bool SearchBuffer::needsMoreContext() const
+{
+    return m_needsMoreContext;
+}
+
+inline void SearchBuffer::prependContext(const UChar* characters, size_t length)
+{
+    ASSERT(m_needsMoreContext);
+    ASSERT(m_prefixLength == m_buffer.size());
+
+    if (!length)
+        return;
+
+    m_atBreak = false;
+
+    size_t wordBoundaryContextStart = length;
+    if (wordBoundaryContextStart) {
+        U16_BACK_1(characters, 0, wordBoundaryContextStart);
+        wordBoundaryContextStart = startOfLastWordBoundaryContext(characters, wordBoundaryContextStart);
+    }
+
+    size_t usableLength = min(m_buffer.capacity() - m_prefixLength, length - wordBoundaryContextStart);
+    m_buffer.prepend(characters + length - usableLength, usableLength);
+    m_prefixLength += usableLength;
+
+    if (wordBoundaryContextStart || m_prefixLength == m_buffer.capacity())
+        m_needsMoreContext = false;
+}
+
+inline bool SearchBuffer::atBreak() const
+{
+    return m_atBreak;
+}
+
+inline void SearchBuffer::reachedBreak()
+{
+    m_atBreak = true;
+}
+
+inline bool SearchBuffer::isBadMatch(const UChar* match, size_t matchLength) const
+{
+    // This function implements the kana workaround. If usearch treats
+    // it as a match, but we do not want to, then it's a "bad match".
+    if (!m_targetRequiresKanaWorkaround)
+        return false;
+
+    // Normalize into a match buffer. We reuse a single buffer rather than
+    // creating a new one each time.
+    normalizeCharacters(match, matchLength, m_normalizedMatch);
+
+    const UChar* a = m_normalizedTarget.begin();
+    const UChar* aEnd = m_normalizedTarget.end();
+
+    const UChar* b = m_normalizedMatch.begin();
+    const UChar* bEnd = m_normalizedMatch.end();
+
+    while (true) {
+        // Skip runs of non-kana-letter characters. This is necessary so we can
+        // correctly handle strings where the target and match have different-length
+        // runs of characters that match, while still double checking the correctness
+        // of matches of kana letters with other kana letters.
+        while (a != aEnd && !isKanaLetter(*a))
+            ++a;
+        while (b != bEnd && !isKanaLetter(*b))
+            ++b;
+
+        // If we reached the end of either the target or the match, we should have
+        // reached the end of both; both should have the same number of kana letters.
+        if (a == aEnd || b == bEnd) {
+            ASSERT(a == aEnd);
+            ASSERT(b == bEnd);
+            return false;
+        }
+
+        // Check for differences in the kana letter character itself.
+        if (isSmallKanaLetter(*a) != isSmallKanaLetter(*b))
+            return true;
+        if (composedVoicedSoundMark(*a) != composedVoicedSoundMark(*b))
+            return true;
+        ++a;
+        ++b;
+
+        // Check for differences in combining voiced sound marks found after the letter.
+        while (1) {
+            if (!(a != aEnd && isCombiningVoicedSoundMark(*a))) {
+                if (b != bEnd && isCombiningVoicedSoundMark(*b))
+                    return true;
+                break;
+            }
+            if (!(b != bEnd && isCombiningVoicedSoundMark(*b)))
+                return true;
+            if (*a != *b)
+                return true;
+            ++a;
+            ++b;
+        }
+    }
+}
+
+inline bool SearchBuffer::isWordStartMatch(size_t start, size_t length) const
+{
+    ASSERT(m_options & AtWordStarts);
+
+    if (!start)
+        return true;
+
+    if (m_options & TreatMedialCapitalAsWordStart) {
+        int size = m_buffer.size();
+        int offset = start;
+        UChar32 firstCharacter;
+        U16_GET(m_buffer.data(), 0, offset, size, firstCharacter);
+        UChar32 previousCharacter;
+        U16_PREV(m_buffer.data(), 0, offset, previousCharacter);
+
+        if (isSeparator(firstCharacter)) {
+            // The start of a separator run is a word start (".org" in "webkit.org").
+            if (!isSeparator(previousCharacter))
+                return true;
+        } else if (isASCIIUpper(firstCharacter)) {
+            // The start of an uppercase run is a word start ("Kit" in "WebKit").
+            if (!isASCIIUpper(previousCharacter))
+                return true;
+            // The last character of an uppercase run followed by a non-separator, non-digit
+            // is a word start ("Request" in "XMLHTTPRequest").
+            offset = start;
+            U16_FWD_1(m_buffer.data(), offset, size);
+            UChar32 nextCharacter = 0;
+            if (offset < size)
+                U16_GET(m_buffer.data(), 0, offset, size, nextCharacter);
+            if (!isASCIIUpper(nextCharacter) && !isASCIIDigit(nextCharacter) && !isSeparator(nextCharacter))
+                return true;
+        } else if (isASCIIDigit(firstCharacter)) {
+            // The start of a digit run is a word start ("2" in "WebKit2").
+            if (!isASCIIDigit(previousCharacter))
+                return true;
+        } else if (isSeparator(previousCharacter) || isASCIIDigit(previousCharacter)) {
+            // The start of a non-separator, non-uppercase, non-digit run is a word start,
+            // except after an uppercase. ("org" in "webkit.org", but not "ore" in "WebCore").
+            return true;
+        }
+    }
+
+    size_t wordBreakSearchStart = start + length;
+    while (wordBreakSearchStart > start)
+        wordBreakSearchStart = findNextWordFromIndex(m_buffer.data(), m_buffer.size(), wordBreakSearchStart, false /* backwards */);
+    return wordBreakSearchStart == start;
+}
+
+inline size_t SearchBuffer::search(size_t& start)
+{
+    size_t size = m_buffer.size();
+    if (m_atBreak) {
+        if (!size)
+            return 0;
+    } else {
+        if (size != m_buffer.capacity())
+            return 0;
+    }
+
+    UStringSearch* searcher = WebCore::searcher();
+
+    UErrorCode status = U_ZERO_ERROR;
+    usearch_setText(searcher, m_buffer.data(), size, &status);
+    ASSERT(status == U_ZERO_ERROR);
+
+    usearch_setOffset(searcher, m_prefixLength, &status);
+    ASSERT(status == U_ZERO_ERROR);
+
+    int matchStart = usearch_next(searcher, &status);
+    ASSERT(status == U_ZERO_ERROR);
+
+nextMatch:
+    if (!(matchStart >= 0 && static_cast<size_t>(matchStart) < size)) {
+        ASSERT(matchStart == USEARCH_DONE);
+        return 0;
+    }
+
+    // Matches that start in the overlap area are only tentative.
+    // The same match may appear later, matching more characters,
+    // possibly including a combining character that's not yet in the buffer.
+    if (!m_atBreak && static_cast<size_t>(matchStart) >= size - m_overlap) {
+        size_t overlap = m_overlap;
+        if (m_options & AtWordStarts) {
+            // Ensure that there is sufficient context before matchStart the next time around for
+            // determining if it is at a word boundary.
+            int wordBoundaryContextStart = matchStart;
+            U16_BACK_1(m_buffer.data(), 0, wordBoundaryContextStart);
+            wordBoundaryContextStart = startOfLastWordBoundaryContext(m_buffer.data(), wordBoundaryContextStart);
+            overlap = min(size - 1, max(overlap, size - wordBoundaryContextStart));
+        }
+        memcpy(m_buffer.data(), m_buffer.data() + size - overlap, overlap * sizeof(UChar));
+        m_prefixLength -= min(m_prefixLength, size - overlap);
+        m_buffer.shrink(overlap);
+        return 0;
+    }
+
+    size_t matchedLength = usearch_getMatchedLength(searcher);
+    ASSERT(matchStart + matchedLength <= size);
+
+    // If this match is "bad", move on to the next match.
+    if (isBadMatch(m_buffer.data() + matchStart, matchedLength) || ((m_options & AtWordStarts) && !isWordStartMatch(matchStart, matchedLength))) {
+        matchStart = usearch_next(searcher, &status);
+        ASSERT(status == U_ZERO_ERROR);
+        goto nextMatch;
+    }
+
+    size_t newSize = size - (matchStart + 1);
+    memmove(m_buffer.data(), m_buffer.data() + matchStart + 1, newSize * sizeof(UChar));
+    m_prefixLength -= min<size_t>(m_prefixLength, matchStart + 1);
+    m_buffer.shrink(newSize);
+
+    start = size - matchStart;
+    return matchedLength;
+}
+
+#else // !ICU_UNICODE
+
+inline SearchBuffer::SearchBuffer(const String& target, FindOptions options)
+    : m_target(options & CaseInsensitive ? target.foldCase() : target)
+    , m_options(options)
+    , m_buffer(m_target.length())
+    , m_isCharacterStartBuffer(m_target.length())
+    , m_isBufferFull(false)
+    , m_cursor(0)
+{
+    ASSERT(!m_target.isEmpty());
+    m_target.replace(noBreakSpace, ' ');
+    foldQuoteMarksAndSoftHyphens(m_target);
+}
+
+inline SearchBuffer::~SearchBuffer()
+{
+}
+
+inline void SearchBuffer::reachedBreak()
+{
+    m_cursor = 0;
+    m_isBufferFull = false;
+}
+
+inline bool SearchBuffer::atBreak() const
+{
+    return !m_cursor && !m_isBufferFull;
+}
+
+inline void SearchBuffer::append(UChar c, bool isStart)
+{
+    m_buffer[m_cursor] = c == noBreakSpace ? ' ' : foldQuoteMarkOrSoftHyphen(c);
+    m_isCharacterStartBuffer[m_cursor] = isStart;
+    if (++m_cursor == m_target.length()) {
+        m_cursor = 0;
+        m_isBufferFull = true;
+    }
+}
+
+inline size_t SearchBuffer::append(const UChar* characters, size_t length)
+{
+    ASSERT(length);
+    if (!(m_options & CaseInsensitive)) {
+        append(characters[0], true);
+        return 1;
+    }
+    const int maxFoldedCharacters = 16; // sensible maximum is 3, this should be more than enough
+    UChar foldedCharacters[maxFoldedCharacters];
+    bool error;
+    int numFoldedCharacters = foldCase(foldedCharacters, maxFoldedCharacters, characters, 1, &error);
+    ASSERT(!error);
+    ASSERT(numFoldedCharacters);
+    ASSERT(numFoldedCharacters <= maxFoldedCharacters);
+    if (!error && numFoldedCharacters) {
+        numFoldedCharacters = min(numFoldedCharacters, maxFoldedCharacters);
+        append(foldedCharacters[0], true);
+        for (int i = 1; i < numFoldedCharacters; ++i)
+            append(foldedCharacters[i], false);
+    }
+    return 1;
+}
+
+inline bool SearchBuffer::needsMoreContext() const
+{
+    return false;
+}
+
+void SearchBuffer::prependContext(const UChar*, size_t)
+{
+    ASSERT_NOT_REACHED();
+}
+
+inline size_t SearchBuffer::search(size_t& start)
+{
+    if (!m_isBufferFull)
+        return 0;
+    if (!m_isCharacterStartBuffer[m_cursor])
+        return 0;
+
+    size_t tailSpace = m_target.length() - m_cursor;
+    if (memcmp(&m_buffer[m_cursor], m_target.characters(), tailSpace * sizeof(UChar)) != 0)
+        return 0;
+    if (memcmp(&m_buffer[0], m_target.characters() + tailSpace, m_cursor * sizeof(UChar)) != 0)
+        return 0;
+
+    start = length();
+
+    // Now that we've found a match once, we don't want to find it again, because those
+    // are the SearchBuffer semantics, allowing for a buffer where you append more than one
+    // character at a time. To do this we take advantage of m_isCharacterStartBuffer, but if
+    // we want to get rid of that in the future we could track this with a separate boolean
+    // or even move the characters to the start of the buffer and set m_isBufferFull to false.
+    m_isCharacterStartBuffer[m_cursor] = false;
+
+    return start;
+}
+
+// Returns the number of characters that were appended to the buffer (what we are searching in).
+// That's not necessarily the same length as the passed-in target string, because case folding
+// can make two strings match even though they're not the same length.
+size_t SearchBuffer::length() const
+{
+    size_t bufferSize = m_target.length();
+    size_t length = 0;
+    for (size_t i = 0; i < bufferSize; ++i)
+        length += m_isCharacterStartBuffer[i];
+    return length;
+}
+
+#endif // !ICU_UNICODE
+
+// --------
+
+int TextIterator::rangeLength(const Range* r, bool forSelectionPreservation)
+{
+    int length = 0;
+    for (TextIterator it(r, forSelectionPreservation ? TextIteratorEmitsCharactersBetweenAllVisiblePositions : TextIteratorDefaultBehavior); !it.atEnd(); it.advance())
+        length += it.length();
+    
+    return length;
+}
+
+PassRefPtr<Range> TextIterator::subrange(Range* entireRange, int characterOffset, int characterCount)
+{
+    CharacterIterator entireRangeIterator(entireRange);
+    return characterSubrange(entireRangeIterator, characterOffset, characterCount);
+}
+
+PassRefPtr<Range> TextIterator::rangeFromLocationAndLength(Element* scope, int rangeLocation, int rangeLength, bool forSelectionPreservation)
+{
+    RefPtr<Range> resultRange = scope->document()->createRange();
+
+    int docTextPosition = 0;
+    int rangeEnd = rangeLocation + rangeLength;
+    bool startRangeFound = false;
+
+    RefPtr<Range> textRunRange;
+
+    TextIterator it(rangeOfContents(scope).get(), forSelectionPreservation ? TextIteratorEmitsCharactersBetweenAllVisiblePositions : TextIteratorDefaultBehavior);
+    
+    // FIXME: the atEnd() check shouldn't be necessary, workaround for <http://bugs.webkit.org/show_bug.cgi?id=6289>.
+    if (rangeLocation == 0 && rangeLength == 0 && it.atEnd()) {
+        textRunRange = it.range();
+        
+        ExceptionCode ec = 0;
+        resultRange->setStart(textRunRange->startContainer(), 0, ec);
+        ASSERT(!ec);
+        resultRange->setEnd(textRunRange->startContainer(), 0, ec);
+        ASSERT(!ec);
+        
+        return resultRange.release();
+    }
+
+    for (; !it.atEnd(); it.advance()) {
+        int len = it.length();
+        textRunRange = it.range();
+        
+        bool foundStart = rangeLocation >= docTextPosition && rangeLocation <= docTextPosition + len;
+        bool foundEnd = rangeEnd >= docTextPosition && rangeEnd <= docTextPosition + len;
+        
+        // Fix textRunRange->endPosition(), but only if foundStart || foundEnd, because it is only
+        // in those cases that textRunRange is used.
+        if (foundEnd) {
+            // FIXME: This is a workaround for the fact that the end of a run is often at the wrong
+            // position for emitted '\n's.
+            if (len == 1 && it.characters()[0] == '\n') {
+                scope->document()->updateLayoutIgnorePendingStylesheets();
+                it.advance();
+                if (!it.atEnd()) {
+                    RefPtr<Range> range = it.range();
+                    ExceptionCode ec = 0;
+                    textRunRange->setEnd(range->startContainer(), range->startOffset(), ec);
+                    ASSERT(!ec);
+                } else {
+                    Position runStart = textRunRange->startPosition();
+                    Position runEnd = VisiblePosition(runStart).next().deepEquivalent();
+                    if (runEnd.isNotNull()) {
+                        ExceptionCode ec = 0;
+                        textRunRange->setEnd(runEnd.node(), runEnd.deprecatedEditingOffset(), ec);
+                        ASSERT(!ec);
+                    }
+                }
+            }
+        }
+
+        if (foundStart) {
+            startRangeFound = true;
+            int exception = 0;
+            if (textRunRange->startContainer()->isTextNode()) {
+                int offset = rangeLocation - docTextPosition;
+                resultRange->setStart(textRunRange->startContainer(), offset + textRunRange->startOffset(), exception);
+            } else {
+                if (rangeLocation == docTextPosition)
+                    resultRange->setStart(textRunRange->startContainer(), textRunRange->startOffset(), exception);
+                else
+                    resultRange->setStart(textRunRange->endContainer(), textRunRange->endOffset(), exception);
+            }
+        }
+
+        if (foundEnd) {
+            int exception = 0;
+            if (textRunRange->startContainer()->isTextNode()) {
+                int offset = rangeEnd - docTextPosition;
+                resultRange->setEnd(textRunRange->startContainer(), offset + textRunRange->startOffset(), exception);
+            } else {
+                if (rangeEnd == docTextPosition)
+                    resultRange->setEnd(textRunRange->startContainer(), textRunRange->startOffset(), exception);
+                else
+                    resultRange->setEnd(textRunRange->endContainer(), textRunRange->endOffset(), exception);
+            }
+            docTextPosition += len;
+            break;
+        }
+        docTextPosition += len;
+    }
+    
+    if (!startRangeFound)
+        return 0;
+    
+    if (rangeLength != 0 && rangeEnd > docTextPosition) { // rangeEnd is out of bounds
+        int exception = 0;
+        resultRange->setEnd(textRunRange->endContainer(), textRunRange->endOffset(), exception);
+    }
+    
+    return resultRange.release();
+}
+
+// --------
+    
+UChar* plainTextToMallocAllocatedBuffer(const Range* r, unsigned& bufferLength, bool isDisplayString, TextIteratorBehavior defaultBehavior)
+{
+    UChar* result = 0;
+
+    // Do this in pieces to avoid massive reallocations if there is a large amount of text.
+    // Use system malloc for buffers since they can consume lots of memory and current TCMalloc is unable return it back to OS.
+    static const unsigned cMaxSegmentSize = 1 << 16;
+    bufferLength = 0;
+    typedef pair<UChar*, unsigned> TextSegment;
+    OwnPtr<Vector<TextSegment> > textSegments;
+    Vector<UChar> textBuffer;
+    textBuffer.reserveInitialCapacity(cMaxSegmentSize);
+    TextIteratorBehavior behavior = defaultBehavior;
+    if (!isDisplayString)
+        behavior = static_cast<TextIteratorBehavior>(behavior | TextIteratorEmitsTextsWithoutTranscoding);
+    
+    for (TextIterator it(r, behavior); !it.atEnd(); it.advance()) {
+        if (textBuffer.size() && textBuffer.size() + it.length() > cMaxSegmentSize) {
+            UChar* newSegmentBuffer = static_cast<UChar*>(malloc(textBuffer.size() * sizeof(UChar)));
+            if (!newSegmentBuffer)
+                goto exit;
+            memcpy(newSegmentBuffer, textBuffer.data(), textBuffer.size() * sizeof(UChar));
+            if (!textSegments)
+                textSegments = adoptPtr(new Vector<TextSegment>);
+            textSegments->append(make_pair(newSegmentBuffer, (unsigned)textBuffer.size()));
+            textBuffer.clear();
+        }
+        textBuffer.append(it.characters(), it.length());
+        bufferLength += it.length();
+    }
+
+    if (!bufferLength)
+        return 0;
+
+    // Since we know the size now, we can make a single buffer out of the pieces with one big alloc
+    result = static_cast<UChar*>(malloc(bufferLength * sizeof(UChar)));
+    if (!result)
+        goto exit;
+
+    {
+        UChar* resultPos = result;
+        if (textSegments) {
+            unsigned size = textSegments->size();
+            for (unsigned i = 0; i < size; ++i) {
+                const TextSegment& segment = textSegments->at(i);
+                memcpy(resultPos, segment.first, segment.second * sizeof(UChar));
+                resultPos += segment.second;
+            }
+        }
+        memcpy(resultPos, textBuffer.data(), textBuffer.size() * sizeof(UChar));
+    }
+
+exit:
+    if (textSegments) {
+        unsigned size = textSegments->size();
+        for (unsigned i = 0; i < size; ++i)
+            free(textSegments->at(i).first);
+    }
+    
+    if (isDisplayString && r->ownerDocument())
+        r->ownerDocument()->displayBufferModifiedByEncoding(result, bufferLength);
+
+    return result;
+}
+
+String plainText(const Range* r, TextIteratorBehavior defaultBehavior)
+{
+    unsigned length;
+    UChar* buf = plainTextToMallocAllocatedBuffer(r, length, false, defaultBehavior);
+    if (!buf)
+        return "";
+    String result(buf, length);
+    free(buf);
+    return result;
+}
+
+static inline bool isAllCollapsibleWhitespace(const String& string)
+{
+    const UChar* characters = string.characters();
+    unsigned length = string.length();
+    for (unsigned i = 0; i < length; ++i) {
+        if (!isCollapsibleWhitespace(characters[i]))
+            return false;
+    }
+    return true;
+}
+
+static PassRefPtr<Range> collapsedToBoundary(const Range* range, bool forward)
+{
+    ExceptionCode ec = 0;
+    RefPtr<Range> result = range->cloneRange(ec);
+    ASSERT(!ec);
+    result->collapse(!forward, ec);
+    ASSERT(!ec);
+    return result.release();
+}
+
+static size_t findPlainText(CharacterIterator& it, const String& target, FindOptions options, size_t& matchStart)
+{
+    matchStart = 0;
+    size_t matchLength = 0;
+
+    SearchBuffer buffer(target, options);
+
+    if (buffer.needsMoreContext()) {
+        RefPtr<Range> startRange = it.range();
+        RefPtr<Range> beforeStartRange = startRange->ownerDocument()->createRange();
+        ExceptionCode ec = 0;
+        beforeStartRange->setEnd(startRange->startContainer(), startRange->startOffset(), ec);
+        for (SimplifiedBackwardsTextIterator backwardsIterator(beforeStartRange.get()); !backwardsIterator.atEnd(); backwardsIterator.advance()) {
+            buffer.prependContext(backwardsIterator.characters(), backwardsIterator.length());
+            if (!buffer.needsMoreContext())
+                break;
+        }
+    }
+
+    while (!it.atEnd()) {
+        it.advance(buffer.append(it.characters(), it.length()));
+tryAgain:
+        size_t matchStartOffset;
+        if (size_t newMatchLength = buffer.search(matchStartOffset)) {
+            // Note that we found a match, and where we found it.
+            size_t lastCharacterInBufferOffset = it.characterOffset();
+            ASSERT(lastCharacterInBufferOffset >= matchStartOffset);
+            matchStart = lastCharacterInBufferOffset - matchStartOffset;
+            matchLength = newMatchLength;
+            // If searching forward, stop on the first match.
+            // If searching backward, don't stop, so we end up with the last match.
+            if (!(options & Backwards))
+                break;
+            goto tryAgain;
+        }
+        if (it.atBreak() && !buffer.atBreak()) {
+            buffer.reachedBreak();
+            goto tryAgain;
+        }
+    }
+
+    return matchLength;
+}
+
+PassRefPtr<Range> findPlainText(const Range* range, const String& target, bool forward, bool caseSensitive)
+{
+    return findPlainText(range, target, (forward ? 0 : Backwards) | (caseSensitive ? 0 : CaseInsensitive));
+}
+
+PassRefPtr<Range> findPlainText(const Range* range, const String& target, FindOptions options)
+{
+    // First, find the text.
+    size_t matchStart;
+    size_t matchLength;
+    {
+        CharacterIterator findIterator(range, TextIteratorEntersTextControls);
+        matchLength = findPlainText(findIterator, target, options, matchStart);
+        if (!matchLength)
+            return collapsedToBoundary(range, !(options & Backwards));
+    }
+
+    // Then, find the document position of the start and the end of the text.
+    CharacterIterator computeRangeIterator(range, TextIteratorEntersTextControls);
+    return characterSubrange(computeRangeIterator, matchStart, matchLength);
+}
+
+}