third_party/WebKit/Source/platform/fonts/UTF16TextIterator.h

/*
 * Copyright (C) Research In Motion Limited 2011. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#ifndef UTF16TextIterator_h
#define UTF16TextIterator_h

#include "platform/PlatformExport.h"
#include "wtf/Allocator.h"
#include "wtf/text/CharacterNames.h"
#include "wtf/text/WTFString.h"

namespace blink {

class PLATFORM_EXPORT UTF16TextIterator {
  USING_FAST_MALLOC(UTF16TextIterator);
  WTF_MAKE_NONCOPYABLE(UTF16TextIterator);

 public:
  // The passed in UChar pointer starts at 'offset'. The iterator operates on
  // the range [offset, endOffset].
  // 'length' denotes the maximum length of the UChar array, which might exceed
  // 'endOffset'.
  UTF16TextIterator(const UChar*, int length);

  // FIXME: The offset/endOffset fields are only used by the SimpleShaper,
  // remove once HarfBuzz is used for all text.
  UTF16TextIterator(const UChar*, int offset, int endOffset, int length);

  inline bool consume(UChar32& character) {
    if (m_offset >= m_endOffset)
      return false;

    character = *m_characters;
    m_currentGlyphLength = 1;
    if (!U16_IS_SURROGATE(character))
      return true;

    return consumeSurrogatePair(character);
  }

  void advance() {
    m_characters += m_currentGlyphLength;
    m_offset += m_currentGlyphLength;
  }

  int offset() const { return m_offset; }
  const UChar* characters() const { return m_characters; }
  const UChar* glyphEnd() const { return m_characters + m_currentGlyphLength; }
  // FIXME: Only used by SimpleShaper, should be removed once the SimpleShaper
  // is removed.
  unsigned glyphLength() const { return m_currentGlyphLength; }

 private:
  bool isValidSurrogatePair(UChar32&);
  bool consumeSurrogatePair(UChar32&);
  void consumeMultipleUChar();

  const UChar* m_characters;
  const UChar* m_charactersEnd;
  int m_offset;
  int m_endOffset;
  unsigned m_currentGlyphLength;
};

}  // namespace blink

#endif