third_party/WebKit/Source/core/editing/iterators/TextIteratorTextState.cpp

/*
 * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 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 "core/editing/iterators/TextIteratorTextState.h"

#include "core/layout/LayoutText.h"

namespace blink {

TextIteratorTextState::TextIteratorTextState(bool emitsOriginalText)
    : m_textLength(0),
      m_singleCharacterBuffer(0),
      m_positionNode(nullptr),
      m_positionStartOffset(0),
      m_positionEndOffset(0),
      m_hasEmitted(false),
      m_lastCharacter(0),
      m_emitsOriginalText(emitsOriginalText) {}

UChar TextIteratorTextState::characterAt(unsigned index) const {
  ASSERT_WITH_SECURITY_IMPLICATION(index < static_cast<unsigned>(length()));
  if (!(index < static_cast<unsigned>(length())))
    return 0;

  if (m_singleCharacterBuffer) {
    DCHECK_EQ(index, 0u);
    DCHECK_EQ(length(), 1);
    return m_singleCharacterBuffer;
  }

  return string()[positionStartOffset() + index];
}

String TextIteratorTextState::substring(unsigned position,
                                        unsigned length) const {
  ASSERT_WITH_SECURITY_IMPLICATION(position <=
                                   static_cast<unsigned>(this->length()));
  ASSERT_WITH_SECURITY_IMPLICATION(position + length <=
                                   static_cast<unsigned>(this->length()));
  if (!length)
    return emptyString();
  if (m_singleCharacterBuffer) {
    DCHECK_EQ(position, 0u);
    DCHECK_EQ(length, 1u);
    return String(&m_singleCharacterBuffer, 1);
  }
  return string().substring(positionStartOffset() + position, length);
}

void TextIteratorTextState::appendTextToStringBuilder(
    StringBuilder& builder,
    unsigned position,
    unsigned maxLength) const {
  unsigned lengthToAppend =
      std::min(static_cast<unsigned>(length()) - position, maxLength);
  if (!lengthToAppend)
    return;
  if (m_singleCharacterBuffer) {
    DCHECK_EQ(position, 0u);
    builder.append(m_singleCharacterBuffer);
  } else {
    builder.append(string(), positionStartOffset() + position, lengthToAppend);
  }
}

void TextIteratorTextState::updateForReplacedElement(Node* baseNode) {
  m_hasEmitted = true;
  m_positionNode = baseNode->parentNode();
  m_positionOffsetBaseNode = baseNode;
  m_positionStartOffset = 0;
  m_positionEndOffset = 1;
  m_singleCharacterBuffer = 0;

  m_textLength = 0;
  m_lastCharacter = 0;
}

void TextIteratorTextState::emitAltText(Node* node) {
  m_text = toHTMLElement(node)->altText();
  m_textLength = m_text.length();
  m_lastCharacter = m_textLength ? m_text[m_textLength - 1] : 0;
}

void TextIteratorTextState::flushPositionOffsets() const {
  if (!m_positionOffsetBaseNode)
    return;
  int index = m_positionOffsetBaseNode->nodeIndex();
  m_positionStartOffset += index;
  m_positionEndOffset += index;
  m_positionOffsetBaseNode = nullptr;
}

void TextIteratorTextState::spliceBuffer(UChar c,
                                         Node* textNode,
                                         Node* offsetBaseNode,
                                         int textStartOffset,
                                         int textEndOffset) {
  DCHECK(textNode);
  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;
  DCHECK(m_singleCharacterBuffer);
  m_textLength = 1;

  // remember some iteration state
  m_lastCharacter = c;
}

void TextIteratorTextState::emitText(Node* textNode,
                                     LayoutText* layoutObject,
                                     int textStartOffset,
                                     int textEndOffset) {
  DCHECK(textNode);
  m_text =
      m_emitsOriginalText ? layoutObject->originalText() : layoutObject->text();
  DCHECK(!m_text.isEmpty());
  DCHECK_LE(0, textStartOffset);
  DCHECK_LT(textStartOffset, static_cast<int>(m_text.length()));
  DCHECK_LE(0, textEndOffset);
  DCHECK_LE(textEndOffset, static_cast<int>(m_text.length()));
  DCHECK_LE(textStartOffset, textEndOffset);

  m_positionNode = textNode;
  m_positionOffsetBaseNode = nullptr;
  m_positionStartOffset = textStartOffset;
  m_positionEndOffset = textEndOffset;
  m_singleCharacterBuffer = 0;
  m_textLength = textEndOffset - textStartOffset;
  m_lastCharacter = m_text[textEndOffset - 1];

  m_hasEmitted = true;
}

void TextIteratorTextState::appendTextTo(ForwardsTextBuffer* output,
                                         unsigned position,
                                         unsigned lengthToAppend) const {
  ASSERT_WITH_SECURITY_IMPLICATION(position + lengthToAppend <=
                                   static_cast<unsigned>(length()));
  // Make sure there's no integer overflow.
  ASSERT_WITH_SECURITY_IMPLICATION(position + lengthToAppend >= position);
  if (!lengthToAppend)
    return;
  DCHECK(output);
  if (m_singleCharacterBuffer) {
    DCHECK_EQ(position, 0u);
    DCHECK_EQ(length(), 1);
    output->pushCharacters(m_singleCharacterBuffer, 1);
    return;
  }
  if (positionNode()) {
    flushPositionOffsets();
    unsigned offset = positionStartOffset() + position;
    if (string().is8Bit())
      output->pushRange(string().characters8() + offset, lengthToAppend);
    else
      output->pushRange(string().characters16() + offset, lengthToAppend);
    return;
  }
  // We shouldn't be attempting to append text that doesn't exist.
  NOTREACHED();
}

}  // namespace blink