third_party/WebKit/Source/core/editing/iterators/WordAwareIterator.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/WordAwareIterator.h"

namespace blink {

WordAwareIterator::WordAwareIterator(const Position& start, const Position& end)
    // So we consider the first chunk from the text iterator.
    : m_didLookAhead(true),
      m_textIterator(start, end) {
  advance();  // Get in position over the first chunk of text.
}

WordAwareIterator::~WordAwareIterator() {}

// FIXME: Performance could be bad for huge spans next to each other that don't fall on word boundaries.

void WordAwareIterator::advance() {
  m_buffer.clear();

  // If last time we did a look-ahead, start with that looked-ahead chunk now
  if (!m_didLookAhead) {
    DCHECK(!m_textIterator.atEnd());
    m_textIterator.advance();
  }
  m_didLookAhead = false;

  // Go to next non-empty chunk.
  while (!m_textIterator.atEnd() && !m_textIterator.length())
    m_textIterator.advance();

  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.characterAt(m_textIterator.length() - 1)))
      return;

    // If this is the first chunk that failed, save it in m_buffer before look ahead.
    if (m_buffer.isEmpty())
      m_textIterator.copyTextTo(&m_buffer);

    // 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() ||
        isSpaceOrNewline(m_textIterator.text().characterAt(0))) {
      m_didLookAhead = true;
      return;
    }

    // Start gobbling chunks until we get to a suitable stopping point
    m_textIterator.copyTextTo(&m_buffer);
  }
}

int WordAwareIterator::length() const {
  if (!m_buffer.isEmpty())
    return m_buffer.size();
  return m_textIterator.length();
}

String WordAwareIterator::substring(unsigned position, unsigned length) const {
  if (!m_buffer.isEmpty())
    return String(m_buffer.data() + position, length);
  return m_textIterator.text().substring(position, length);
}

UChar WordAwareIterator::characterAt(unsigned index) const {
  if (!m_buffer.isEmpty())
    return m_buffer[index];
  return m_textIterator.text().characterAt(index);
}

}  // namespace blink