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  #include "qabstractfileengine.h"
  #include "private/qabstractfileengine_p.h"
  #ifdef QT_BUILD_CORE_LIB
  #include "private/qresource_p.h"
  #endif
  #include "qdatetime.h"
  #include "qreadwritelock.h"
  #include "qvariant.h"
  // built-in handlers
  #include "qfsfileengine.h"
  #include "qdiriterator.h"
  #include "qstringbuilder.h"
  
  #include <QtCore/private/qfilesystementry_p.h>
  #include <QtCore/private/qfilesystemmetadata_p.h>
  #include <QtCore/private/qfilesystemengine_p.h>
  
  QT_BEGIN_NAMESPACE
  
  /*!
      \class QAbstractFileEngineHandler
      \reentrant
  
      \brief The QAbstractFileEngineHandler class provides a way to register
      custom file engines with your application.
  
      \ingroup io
      \since 4.1
  
      QAbstractFileEngineHandler is a factory for creating QAbstractFileEngine
      objects (file engines), which are used internally by QFile, QFileInfo, and
      QDir when working with files and directories.
  
      When you open a file, Qt chooses a suitable file engine by passing the
      file name from QFile or QDir through an internal list of registered file
      engine handlers. The first handler to recognize the file name is used to
      create the engine. Qt provides internal file engines for working with
      regular files and resources, but you can also register your own
      QAbstractFileEngine subclasses.
  
      To install an application-specific file engine, you subclass
      QAbstractFileEngineHandler and reimplement create(). When you instantiate
      the handler (e.g. by creating an instance on the stack or on the heap), it
      will automatically register with Qt. (The latest registered handler takes
      precedence over existing handlers.)
  
      For example:
  
      \snippet doc/src/snippets/code/src_corelib_io_qabstractfileengine.cpp 0
  
      When the handler is destroyed, it is automatically removed from Qt.
  
      The most common approach to registering a handler is to create an instance
      as part of the start-up phase of your application. It is also possible to
      limit the scope of the file engine handler to a particular area of
      interest (e.g. a special file dialog that needs a custom file engine). By
      creating the handler inside a local scope, you can precisely control the
      area in which your engine will be applied without disturbing file
      operations in other parts of your application.
  
      \sa QAbstractFileEngine, QAbstractFileEngine::create()
  */
  
  static bool qt_file_engine_handlers_in_use = false;
  
  /*
      All application-wide handlers are stored in this list. The mutex must be
      acquired to ensure thread safety.
   */
  Q_GLOBAL_STATIC_WITH_ARGS(QReadWriteLock, fileEngineHandlerMutex, (QReadWriteLock::Recursive))
  static bool qt_abstractfileenginehandlerlist_shutDown = false;
  class QAbstractFileEngineHandlerList : public QList<QAbstractFileEngineHandler *>
  {
  public:
      ~QAbstractFileEngineHandlerList()
      {
          QWriteLocker locker(fileEngineHandlerMutex());
          qt_abstractfileenginehandlerlist_shutDown = true;
      }
  };
  Q_GLOBAL_STATIC(QAbstractFileEngineHandlerList, fileEngineHandlers)
  
  /*!
      Constructs a file handler and registers it with Qt. Once created this
      handler's create() function will be called (along with all the other
      handlers) for any paths used. The most recently created handler that
      recognizes the given path (i.e. that returns a QAbstractFileEngine) is
      used for the new path.
  
      \sa create()
   */
  QAbstractFileEngineHandler::QAbstractFileEngineHandler()
  {
      QWriteLocker locker(fileEngineHandlerMutex());
      qt_file_engine_handlers_in_use = true;
      fileEngineHandlers()->prepend(this);
  }
  
  /*!
      Destroys the file handler. This will automatically unregister the handler
      from Qt.
   */
  QAbstractFileEngineHandler::~QAbstractFileEngineHandler()
  {
      QWriteLocker locker(fileEngineHandlerMutex());
      // Remove this handler from the handler list only if the list is valid.
      if (!qt_abstractfileenginehandlerlist_shutDown) {
          QAbstractFileEngineHandlerList *handlers = fileEngineHandlers();
          handlers->removeOne(this);
          if (handlers->isEmpty())
              qt_file_engine_handlers_in_use = false;
      }
  }
  
  /*
     \ìnternal
  
     Handles calls to custom file engine handlers.
  */
  QAbstractFileEngine *qt_custom_file_engine_handler_create(const QString &path)
  {
      QAbstractFileEngine *engine = 0;
  
      if (qt_file_engine_handlers_in_use) {
          QReadLocker locker(fileEngineHandlerMutex());
  
          // check for registered handlers that can load the file
          QAbstractFileEngineHandlerList *handlers = fileEngineHandlers();
          for (int i = 0; i < handlers->size(); i++) {
              if ((engine = handlers->at(i)->create(path)))
                  break;
          }
      }
  
      return engine;
  }
  
  /*!
      \fn QAbstractFileEngine *QAbstractFileEngineHandler::create(const QString &fileName) const
  
      Creates a file engine for file \a fileName. Returns 0 if this
      file handler cannot handle \a fileName.
  
      Example:
  
      \snippet doc/src/snippets/code/src_corelib_io_qabstractfileengine.cpp 1
  
      \sa QAbstractFileEngine::create()
  */
  
  /*!
      Creates and returns a QAbstractFileEngine suitable for processing \a
      fileName.
  
      You should not need to call this function; use QFile, QFileInfo or
      QDir directly instead.
  
      If you reimplemnt this function, it should only return file
      engines that knows how to handle \a fileName; otherwise, it should
      return 0.
  
      \sa QAbstractFileEngineHandler
  */
  QAbstractFileEngine *QAbstractFileEngine::create(const QString &fileName)
  {
      QFileSystemEntry entry(fileName);
      QFileSystemMetaData metaData;
      QAbstractFileEngine *engine = QFileSystemEngine::resolveEntryAndCreateLegacyEngine(entry, metaData);
  
  #ifndef QT_NO_FSFILEENGINE
      if (!engine)
          // fall back to regular file engine
          return new QFSFileEngine(entry.filePath());
  #endif
  
      return engine;
  }
  
  /*!
      \class QAbstractFileEngine
      \reentrant
  
      \brief The QAbstractFileEngine class provides an abstraction for accessing
      the filesystem.
  
      \ingroup io
      \since 4.1
  
      The QDir, QFile, and QFileInfo classes all make use of a
      QAbstractFileEngine internally. If you create your own QAbstractFileEngine
      subclass (and register it with Qt by creating a QAbstractFileEngineHandler
      subclass), your file engine will be used when the path is one that your
      file engine handles.
  
      A QAbstractFileEngine refers to one file or one directory. If the referent
      is a file, the setFileName(), rename(), and remove() functions are
      applicable. If the referent is a directory the mkdir(), rmdir(), and
      entryList() functions are applicable. In all cases the caseSensitive(),
      isRelativePath(), fileFlags(), ownerId(), owner(), and fileTime()
      functions are applicable.
  
      A QAbstractFileEngine subclass can be created to do synchronous network I/O
      based file system operations, local file system operations, or to operate
      as a resource system to access file based resources.
  
     \sa QAbstractFileEngineHandler
  */
  
  /*!
      \enum QAbstractFileEngine::FileName
  
      These values are used to request a file name in a particular
      format.
  
      \value DefaultName The same filename that was passed to the
      QAbstractFileEngine.
      \value BaseName The name of the file excluding the path.
      \value PathName The path to the file excluding the base name.
      \value AbsoluteName The absolute path to the file (including
      the base name).
      \value AbsolutePathName The absolute path to the file (excluding
      the base name).
      \value LinkName The full file name of the file that this file is a
      link to. (This will be empty if this file is not a link.)
      \value CanonicalName Often very similar to LinkName. Will return the true path to the file.
      \value CanonicalPathName Same as CanonicalName, excluding the base name.
      \value BundleName Returns the name of the bundle implies BundleType is set.
  
      \omitvalue NFileNames
  
      \sa fileName(), setFileName()
  */
  
  /*!
      \enum QAbstractFileEngine::FileFlag
  
      The permissions and types of a file, suitable for OR'ing together.
  
      \value ReadOwnerPerm The owner of the file has permission to read
      it.
      \value WriteOwnerPerm The owner of the file has permission to
      write to it.
      \value ExeOwnerPerm The owner of the file has permission to
      execute it.
      \value ReadUserPerm The current user has permission to read the
      file.
      \value WriteUserPerm The current user has permission to write to
      the file.
      \value ExeUserPerm The current user has permission to execute the
      file.
      \value ReadGroupPerm Members of the current user's group have
      permission to read the file.
      \value WriteGroupPerm Members of the current user's group have
      permission to write to the file.
      \value ExeGroupPerm Members of the current user's group have
      permission to execute the file.
      \value ReadOtherPerm All users have permission to read the file.
      \value WriteOtherPerm All users have permission to write to the
      file.
      \value ExeOtherPerm All users have permission to execute the file.
  
      \value LinkType The file is a link to another file (or link) in
      the file system (i.e. not a file or directory).
      \value FileType The file is a regular file to the file system
      (i.e. not a link or directory)
      \value BundleType The file is a Mac OS X bundle implies DirectoryType
      \value DirectoryType The file is a directory in the file system
      (i.e. not a link or file).
  
      \value HiddenFlag The file is hidden.
      \value ExistsFlag The file actually exists in the file system.
      \value RootFlag  The file or the file pointed to is the root of the filesystem.
      \value LocalDiskFlag The file resides on the local disk and can be passed to standard file functions.
      \value Refresh Passing this flag will force the file engine to refresh all flags.
  
      \omitvalue PermsMask
      \omitvalue TypesMask
      \omitvalue FlagsMask
      \omitvalue FileInfoAll
  
      \sa fileFlags(), setFileName()
  */
  
  /*!
      \enum QAbstractFileEngine::FileTime
  
      These are used by the fileTime() function.
  
      \value CreationTime When the file was created.
      \value ModificationTime When the file was most recently modified.
      \value AccessTime When the file was most recently accessed (e.g.
      read or written to).
  
      \sa setFileName()
  */
  
  /*!
      \enum QAbstractFileEngine::FileOwner
  
      \value OwnerUser The user who owns the file.
      \value OwnerGroup The group who owns the file.
  
      \sa owner(), ownerId(), setFileName()
  */
  
  /*!
     Constructs a new QAbstractFileEngine that does not refer to any file or directory.
  
     \sa setFileName()
   */
  QAbstractFileEngine::QAbstractFileEngine() : d_ptr(new QAbstractFileEnginePrivate)
  {
      d_ptr->q_ptr = this;
  }
  
  /*!
     \internal
  
     Constructs a QAbstractFileEngine.
   */
  QAbstractFileEngine::QAbstractFileEngine(QAbstractFileEnginePrivate &dd) : d_ptr(&dd)
  {
      d_ptr->q_ptr = this;
  }
  
  /*!
      Destroys the QAbstractFileEngine.
   */
  QAbstractFileEngine::~QAbstractFileEngine()
  {
  }
  
  /*!
      \fn bool QAbstractFileEngine::open(QIODevice::OpenMode mode)
  
      Opens the file in the specified \a mode. Returns true if the file
      was successfully opened; otherwise returns false.
  
      The \a mode is an OR combination of QIODevice::OpenMode and
      QIODevice::HandlingMode values.
  */
  bool QAbstractFileEngine::open(QIODevice::OpenMode openMode)
  {
      Q_UNUSED(openMode);
      return false;
  }
  
  /*!
      Closes the file, returning true if successful; otherwise returns false.
  
      The default implementation always returns false.
  */
  bool QAbstractFileEngine::close()
  {
      return false;
  }
  
  /*!
      Flushes the open file, returning true if successful; otherwise returns
      false.
  
      The default implementation always returns false.
  */
  bool QAbstractFileEngine::flush()
  {
      return false;
  }
  
  /*!
      Returns the size of the file.
  */
  qint64 QAbstractFileEngine::size() const
  {
      return 0;
  }
  
  /*!
      Returns the current file position.
  
      This is the position of the data read/write head of the file.
  */
  qint64 QAbstractFileEngine::pos() const
  {
      return 0;
  }
  
  /*!
      \fn bool QAbstractFileEngine::seek(qint64 offset)
  
      Sets the file position to the given \a offset. Returns true if
      the position was successfully set; otherwise returns false.
  
      The offset is from the beginning of the file, unless the
      file is sequential.
  
      \sa isSequential()
  */
  bool QAbstractFileEngine::seek(qint64 pos)
  {
      Q_UNUSED(pos);
      return false;
  }
  
  /*!
      Returns true if the file is a sequential access device; returns
      false if the file is a direct access device.
  
      Operations involving size() and seek(int) are not valid on
      sequential devices.
  */
  bool QAbstractFileEngine::isSequential() const
  {
      return false;
  }
  
  /*!
      Requests that the file is deleted from the file system. If the
      operation succeeds return true; otherwise return false.
  
      This virtual function must be reimplemented by all subclasses.
  
      \sa setFileName() rmdir()
   */
  bool QAbstractFileEngine::remove()
  {
      return false;
  }
  
  /*!
      Copies the contents of this file to a file with the name \a newName.
      Returns true on success; otherwise, false is returned.
  */
  bool QAbstractFileEngine::copy(const QString &newName)
  {
      Q_UNUSED(newName);
      return false;
  }
  
  /*!
      Requests that the file be renamed to \a newName in the file
      system. If the operation succeeds return true; otherwise return
      false.
  
      This virtual function must be reimplemented by all subclasses.
  
      \sa setFileName()
   */
  bool QAbstractFileEngine::rename(const QString &newName)
  {
      Q_UNUSED(newName);
      return false;
  }
  
  /*!
      Creates a link from the file currently specified by fileName() to
      \a newName. What a link is depends on the underlying filesystem
      (be it a shortcut on Windows or a symbolic link on Unix). Returns
      true if successful; otherwise returns false.
  */
  bool QAbstractFileEngine::link(const QString &newName)
  {
      Q_UNUSED(newName);
      return false;
  }
  
  /*!
      Requests that the directory \a dirName be created. If
      \a createParentDirectories is true, then any sub-directories in \a dirName
      that don't exist must be created. If \a createParentDirectories is false then
      any sub-directories in \a dirName must already exist for the function to
      succeed. If the operation succeeds return true; otherwise return
      false.
  
      This virtual function must be reimplemented by all subclasses.
  
      \sa setFileName() rmdir() isRelativePath()
   */
  bool QAbstractFileEngine::mkdir(const QString &dirName, bool createParentDirectories) const
  {
      Q_UNUSED(dirName);
      Q_UNUSED(createParentDirectories);
      return false;
  }
  
  /*!
      Requests that the directory \a dirName is deleted from the file
      system. When \a recurseParentDirectories is true, then any empty
      parent-directories in \a dirName must also be deleted. If
      \a recurseParentDirectories is false, only the \a dirName leaf-node
      should be deleted. In most file systems a directory cannot be deleted
      using this function if it is non-empty. If the operation succeeds
      return true; otherwise return false.
  
      This virtual function must be reimplemented by all subclasses.
  
      \sa setFileName() remove() mkdir() isRelativePath()
   */
  bool QAbstractFileEngine::rmdir(const QString &dirName, bool recurseParentDirectories) const
  {
      Q_UNUSED(dirName);
      Q_UNUSED(recurseParentDirectories);
      return false;
  }
  
  /*!
      Requests that the file be set to size \a size. If \a size is larger
      than the current file then it is filled with 0's, if smaller it is
      simply truncated. If the operations succceeds return true; otherwise
      return false;
  
      This virtual function must be reimplemented by all subclasses.
  
      \sa size()
  */
  bool QAbstractFileEngine::setSize(qint64 size)
  {
      Q_UNUSED(size);
      return false;
  }
  
  /*!
      Should return true if the underlying file system is case-sensitive;
      otherwise return false.
  
      This virtual function must be reimplemented by all subclasses.
   */
  bool QAbstractFileEngine::caseSensitive() const
  {
      return false;
  }
  
  /*!
      Return true if the file referred to by this file engine has a
      relative path; otherwise return false.
  
      This virtual function must be reimplemented by all subclasses.
  
      \sa setFileName()
   */
  bool QAbstractFileEngine::isRelativePath() const
  {
      return false;
  }
  
  /*!
      Requests that a list of all the files matching the \a filters
      list based on the \a filterNames in the file engine's directory
      are returned.
  
      Should return an empty list if the file engine refers to a file
      rather than a directory, or if the directory is unreadable or does
      not exist or if nothing matches the specifications.
  
      This virtual function must be reimplemented by all subclasses.
  
      \sa setFileName()
   */
  QStringList QAbstractFileEngine::entryList(QDir::Filters filters, const QStringList &filterNames) const
  {
      QStringList ret;
      QDirIterator it(fileName(), filterNames, filters);
      while (it.hasNext()) {
          it.next();
          ret << it.fileName();
      }
      return ret;
  }
  
  /*!
      This function should return the set of OR'd flags that are true
      for the file engine's file, and that are in the \a type's OR'd
      members.
  
      In your reimplementation you can use the \a type argument as an
      optimization hint and only return the OR'd set of members that are
      true and that match those in \a type; in other words you can
      ignore any members not mentioned in \a type, thus avoiding some
      potentially expensive lookups or system calls.
  
      This virtual function must be reimplemented by all subclasses.
  
      \sa setFileName()
  */
  QAbstractFileEngine::FileFlags QAbstractFileEngine::fileFlags(FileFlags type) const
  {
      Q_UNUSED(type);
      return 0;
  }
  
  /*!
      Requests that the file's permissions be set to \a perms. The argument
      perms will be set to the OR-ed together combination of
      QAbstractFileEngine::FileInfo, with only the QAbstractFileEngine::PermsMask being
      honored. If the operations succceeds return true; otherwise return
      false;
  
      This virtual function must be reimplemented by all subclasses.
  
      \sa size()
  */
  bool QAbstractFileEngine::setPermissions(uint perms)
  {
      Q_UNUSED(perms);
      return false;
  }
  
  /*!
      Return  the file engine's current file name in the format
      specified by \a file.
  
      If you don't handle some \c FileName possibilities, return the
      file name set in setFileName() when an unhandled format is
      requested.
  
      This virtual function must be reimplemented by all subclasses.
  
      \sa setFileName(), FileName
   */
  QString QAbstractFileEngine::fileName(FileName file) const
  {
      Q_UNUSED(file);
      return QString();
  }
  
  /*!
      If \a owner is \c OwnerUser return the ID of the user who owns
      the file. If \a owner is \c OwnerGroup return the ID of the group
      that own the file. If you can't determine the owner return -2.
  
      This virtual function must be reimplemented by all subclasses.
  
      \sa owner() setFileName(), FileOwner
   */
  uint QAbstractFileEngine::ownerId(FileOwner owner) const
  {
      Q_UNUSED(owner);
      return 0;
  }
  
  /*!
      If \a owner is \c OwnerUser return the name of the user who owns
      the file. If \a owner is \c OwnerGroup return the name of the group
      that own the file. If you can't determine the owner return
      QString().
  
      This virtual function must be reimplemented by all subclasses.
  
      \sa ownerId() setFileName(), FileOwner
   */
  QString QAbstractFileEngine::owner(FileOwner owner) const
  {
      Q_UNUSED(owner);
      return QString();
  }
  
  /*!
      If \a time is \c CreationTime, return when the file was created.
      If \a time is \c ModificationTime, return when the file was most
      recently modified. If \a time is \c AccessTime, return when the
      file was most recently accessed (e.g. read or written).
      If the time cannot be determined return QDateTime() (an invalid
      date time).
  
      This virtual function must be reimplemented by all subclasses.
  
      \sa setFileName(), QDateTime, QDateTime::isValid(), FileTime
   */
  QDateTime QAbstractFileEngine::fileTime(FileTime time) const
  {
      Q_UNUSED(time);
      return QDateTime();
  }
  
  /*!
      Sets the file engine's file name to \a file. This file name is the
      file that the rest of the virtual functions will operate on.
  
      This virtual function must be reimplemented by all subclasses.
  
      \sa rename()
   */
  void QAbstractFileEngine::setFileName(const QString &file)
  {
      Q_UNUSED(file);
  }
  
  /*!
      Returns the native file handle for this file engine. This handle must be
      used with care; its value and type are platform specific, and using it
      will most likely lead to non-portable code.
  */
  int QAbstractFileEngine::handle() const
  {
      return -1;
  }
  
  /*!
      \since 4.3
  
      Returns true if the current position is at the end of the file; otherwise,
      returns false.
  
      This function bases its behavior on calling extension() with
      AtEndExtension. If the engine does not support this extension, false is
      returned.
  
      \sa extension(), supportsExtension(), QFile::atEnd()
  */
  bool QAbstractFileEngine::atEnd() const
  {
      return const_cast<QAbstractFileEngine *>(this)->extension(AtEndExtension);
  }
  
  /*!
      \since 4.4
  
      Maps \a size bytes of the file into memory starting at \a offset.
      Returns a pointer to the memory if successful; otherwise returns false
      if, for example, an error occurs.
  
      This function bases its behavior on calling extension() with
      MapExtensionOption. If the engine does not support this extension, 0 is
      returned.
  
      \a flags is currently not used, but could be used in the future.
  
      \sa unmap(), supportsExtension()
   */
  
  uchar *QAbstractFileEngine::map(qint64 offset, qint64 size, QFile::MemoryMapFlags flags)
  {
      MapExtensionOption option;
      option.offset = offset;
      option.size = size;
      option.flags = flags;
      MapExtensionReturn r;
      if (!extension(MapExtension, &option, &r))
          return 0;
      return r.address;
  }
  
  /*!
      \since 4.4
  
      Unmaps the memory \a address.  Returns true if the unmap succeeds; otherwise
      returns false.
  
      This function bases its behavior on calling extension() with
      UnMapExtensionOption. If the engine does not support this extension, false is
      returned.
  
      \sa map(), supportsExtension()
   */
  bool QAbstractFileEngine::unmap(uchar *address)
  {
      UnMapExtensionOption options;
      options.address = address;
      return extension(UnMapExtension, &options);
  }
  
  /*!
      \since 4.3
      \class QAbstractFileEngineIterator
      \brief The QAbstractFileEngineIterator class provides an iterator
      interface for custom file engines.
  
      If all you want is to iterate over entries in a directory, see
      QDirIterator instead. This class is only for custom file engine authors.
  
      QAbstractFileEngineIterator is a unidirectional single-use virtual
      iterator that plugs into QDirIterator, providing transparent proxy
      iteration for custom file engines.
  
      You can subclass QAbstractFileEngineIterator to provide an iterator when
      writing your own file engine. To plug the iterator into your file system,
      you simply return an instance of this subclass from a reimplementation of
      QAbstractFileEngine::beginEntryList().
  
      Example:
  
      \snippet doc/src/snippets/code/src_corelib_io_qabstractfileengine.cpp 2
  
      QAbstractFileEngineIterator is associated with a path, name filters, and
      entry filters. The path is the directory that the iterator lists entries
      in. The name filters and entry filters are provided for file engines that
      can optimize directory listing at the iterator level (e.g., network file
      systems that need to minimize network traffic), but they can also be
      ignored by the iterator subclass; QAbstractFileEngineIterator already
      provides the required filtering logics in the matchesFilters() function.
      You can call dirName() to get the directory name, nameFilters() to get a
      stringlist of name filters, and filters() to get the entry filters.
  
      The pure virtual function hasNext() returns true if the current directory
      has at least one more entry (i.e., the directory name is valid and
      accessible, and we have not reached the end of the entry list), and false
      otherwise. Reimplement next() to seek to the next entry.
  
      The pure virtual function currentFileName() returns the name of the
      current entry without advancing the iterator. The currentFilePath()
      function is provided for convenience; it returns the full path of the
      current entry.
  
      Here is an example of how to implement an iterator that returns each of
      three fixed entries in sequence.
  
      \snippet doc/src/snippets/code/src_corelib_io_qabstractfileengine.cpp 3
  
      Note: QAbstractFileEngineIterator does not deal with QDir::IteratorFlags;
      it simply returns entries for a single directory.
  
      \sa QDirIterator
  */
  
  /*!
      \enum QAbstractFileEngineIterator::EntryInfoType
      \internal
  
      This enum describes the different types of information that can be
      requested through the QAbstractFileEngineIterator::entryInfo() function.
  */
  
  /*!
      \typedef QAbstractFileEngine::Iterator
      \since 4.3
      \relates QAbstractFileEngine
  
      Synonym for QAbstractFileEngineIterator.
  */
  
  class QAbstractFileEngineIteratorPrivate
  {
  public:
      QString path;
      QDir::Filters filters;
      QStringList nameFilters;
      QFileInfo fileInfo;
  };
  
  /*!
      Constructs a QAbstractFileEngineIterator, using the entry filters \a
      filters, and wildcard name filters \a nameFilters.
  */
  QAbstractFileEngineIterator::QAbstractFileEngineIterator(QDir::Filters filters,
                                                           const QStringList &nameFilters)
      : d(new QAbstractFileEngineIteratorPrivate)
  {
      d->nameFilters = nameFilters;
      d->filters = filters;
  }
  
  /*!
      Destroys the QAbstractFileEngineIterator.
  
      \sa QDirIterator
  */
  QAbstractFileEngineIterator::~QAbstractFileEngineIterator()
  {
  }
  
  /*!
      Returns the path for this iterator. QDirIterator is responsible for
      assigning this path; it cannot change during the iterator's lifetime.
  
      \sa nameFilters(), filters()
  */
  QString QAbstractFileEngineIterator::path() const
  {
      return d->path;
  }
  
  /*!
      \internal
  
      Sets the iterator path to \a path. This function is called from within
      QDirIterator.
  */
  void QAbstractFileEngineIterator::setPath(const QString &path)
  {
      d->path = path;
  }
  
  /*!
      Returns the name filters for this iterator.
  
      \sa QDir::nameFilters(), filters(), path()
  */
  QStringList QAbstractFileEngineIterator::nameFilters() const
  {
      return d->nameFilters;
  }
  
  /*!
      Returns the entry filters for this iterator.
  
      \sa QDir::filter(), nameFilters(), path()
  */
  QDir::Filters QAbstractFileEngineIterator::filters() const
  {
      return d->filters;
  }
  
  /*!
      \fn QString QAbstractFileEngineIterator::currentFileName() const = 0
  
      This pure virtual function returns the name of the current directory
      entry, excluding the path.
  
      \sa currentFilePath()
  */
  
  /*!
      Returns the path to the current directory entry. It's the same as
      prepending path() to the return value of currentFileName().
  
      \sa currentFileName()
  */
  QString QAbstractFileEngineIterator::currentFilePath() const
  {
      QString name = currentFileName();
      if (!name.isNull()) {
          QString tmp = path();
          if (!tmp.isEmpty()) {
              if (!tmp.endsWith(QLatin1Char('/')))
                  tmp.append(QLatin1Char('/'));
              name.prepend(tmp);
          }
      }
      return name;
  }
  
  /*!
      The virtual function returns a QFileInfo for the current directory
      entry. This function is provided for convenience. It can also be slightly
      faster than creating a QFileInfo object yourself, as the object returned
      by this function might contain cached information that QFileInfo otherwise
      would have to access through the file engine.
  
      \sa currentFileName()
  */
  QFileInfo QAbstractFileEngineIterator::currentFileInfo() const
  {
      QString path = currentFilePath();
      if (d->fileInfo.filePath() != path)
          d->fileInfo.setFile(path);
  
      // return a shallow copy
      return d->fileInfo;
  }
  
  /*!
      \internal
  
      Returns the entry info \a type for this iterator's current directory entry
      as a QVariant. If \a type is undefined for this entry, a null QVariant is
      returned.
  
      \sa QAbstractFileEngine::beginEntryList(), QDir::beginEntryList()
  */
  QVariant QAbstractFileEngineIterator::entryInfo(EntryInfoType type) const
  {
      Q_UNUSED(type)
      return QVariant();
  }
  
  /*!
      \fn virtual QString QAbstractFileEngineIterator::next() = 0
  
      This pure virtual function advances the iterator to the next directory
      entry, and returns the file path to the current entry.
  
      This function can optionally make use of nameFilters() and filters() to
      optimize its performance.
  
      Reimplement this function in a subclass to advance the iterator.
  
      \sa QDirIterator::next()
  */
  
  /*!
      \fn virtual bool QAbstractFileEngineIterator::hasNext() const = 0
  
      This pure virtual function returns true if there is at least one more
      entry in the current directory (i.e., the iterator path is valid and
      accessible, and the iterator has not reached the end of the entry list).
  
      \sa QDirIterator::hasNext()
  */
  
  /*!
      Returns an instance of a QAbstractFileEngineIterator using \a filters for
      entry filtering and \a filterNames for name filtering. This function is
      called by QDirIterator to initiate directory iteration.
  
      QDirIterator takes ownership of the returned instance, and deletes it when
      it's done.
  
      \sa QDirIterator
  */
  QAbstractFileEngine::Iterator *QAbstractFileEngine::beginEntryList(QDir::Filters filters, const QStringList &filterNames)
  {
      Q_UNUSED(filters);
      Q_UNUSED(filterNames);
      return 0;
  }
  
  /*!
      \internal
  */
  QAbstractFileEngine::Iterator *QAbstractFileEngine::endEntryList()
  {
      return 0;
  }
  
  /*!
      Reads a number of characters from the file into \a data. At most
      \a maxlen characters will be read.
  
      Returns -1 if a fatal error occurs, or 0 if there are no bytes to
      read.
  */
  qint64 QAbstractFileEngine::read(char *data, qint64 maxlen)
  {
      Q_UNUSED(data);
      Q_UNUSED(maxlen);
      return -1;
  }
  
  /*!
      Writes \a len bytes from \a data to the file. Returns the number
      of characters written on success; otherwise returns -1.
  */
  qint64 QAbstractFileEngine::write(const char *data, qint64 len)
  {
      Q_UNUSED(data);
      Q_UNUSED(len);
      return -1;
  }
  
  /*!
      This function reads one line, terminated by a '\n' character, from the
      file info \a data. At most \a maxlen characters will be read. The
      end-of-line character is included.
  */
  qint64 QAbstractFileEngine::readLine(char *data, qint64 maxlen)
  {
      qint64 readSoFar = 0;
      while (readSoFar < maxlen) {
          char c;
          qint64 readResult = read(&c, 1);
          if (readResult <= 0)
              return (readSoFar > 0) ? readSoFar : -1;
          ++readSoFar;
          *data++ = c;
          if (c == '\n')
              return readSoFar;
      }
      return readSoFar;
  }
  
  /*!
     \enum QAbstractFileEngine::Extension
     \since 4.3
  
     This enum describes the types of extensions that the file engine can
     support. Before using these extensions, you must verify that the extension
     is supported (i.e., call supportsExtension()).
  
     \value AtEndExtension Whether the current file position is at the end of
     the file or not. This extension allows file engines that implement local
     buffering to report end-of-file status without having to check the size of
     the file. It is also useful for sequential files, where the size of the
     file cannot be used to determine whether or not you have reached the end.
     This extension returns true if the file is at the end; otherwise it returns
     false. The input and output arguments to extension() are ignored.
  
     \value FastReadLineExtension Whether the file engine provides a
     fast implementation for readLine() or not. If readLine() remains
     unimplemented in the file engine, QAbstractFileEngine will provide
     an implementation based on calling read() repeatedly. If
     supportsExtension() returns false for this extension, however,
     QIODevice can provide a faster implementation by making use of its
     internal buffer. For engines that already provide a fast readLine()
     implementation, returning false for this extension can avoid
     unnnecessary double-buffering in QIODevice.
  
     \value MapExtension Whether the file engine provides the ability to map
     a file to memory.
  
     \value UnMapExtension Whether the file engine provides the ability to
     unmap memory that was previously mapped.
  */
  
  /*!
     \class QAbstractFileEngine::ExtensionOption
     \since 4.3
     \brief provides an extended input argument to QAbstractFileEngine's
     extension support.
  
     \sa QAbstractFileEngine::extension()
  */
  
  /*!
     \class QAbstractFileEngine::ExtensionReturn
     \since 4.3
     \brief provides an extended output argument to QAbstractFileEngine's
     extension support.
  
     \sa QAbstractFileEngine::extension()
  */
  
  /*!
      \since 4.3
  
      This virtual function can be reimplemented in a QAbstractFileEngine
      subclass to provide support for extensions. The \a option argument is
      provided as input to the extension, and this function can store output
      results in \a output.
  
      The behavior of this function is determined by \a extension; see the
      Extension documentation for details.
  
      You can call supportsExtension() to check if an extension is supported by
      the file engine.
  
      By default, no extensions are supported, and this function returns false.
  
      \sa supportsExtension(), Extension
  */
  bool QAbstractFileEngine::extension(Extension extension, const ExtensionOption *option, ExtensionReturn *output)
  {
      Q_UNUSED(extension);
      Q_UNUSED(option);
      Q_UNUSED(output);
      return false;
  }
  
  /*!
      \since 4.3
  
      This virtual function returns true if the file engine supports \a
      extension; otherwise, false is returned. By default, no extensions are
      supported.
  
      \sa extension()
  */
  bool QAbstractFileEngine::supportsExtension(Extension extension) const
  {
      Q_UNUSED(extension);
      return false;
  }
  
  /*!
    Returns the QFile::FileError that resulted from the last failed
    operation. If QFile::UnspecifiedError is returned, QFile will
    use its own idea of the error status.
  
    \sa QFile::FileError, errorString()
   */
  QFile::FileError QAbstractFileEngine::error() const
  {
      Q_D(const QAbstractFileEngine);
      return d->fileError;
  }
  
  /*!
    Returns the human-readable message appropriate to the current error
    reported by error(). If no suitable string is available, an
    empty string is returned.
  
    \sa error()
   */
  QString QAbstractFileEngine::errorString() const
  {
      Q_D(const QAbstractFileEngine);
      return d->errorString;
  }
  
  /*!
      Sets the error type to \a error, and the error string to \a errorString.
      Call this function to set the error values returned by the higher-level
      classes.
  
      \sa QFile::error(), QIODevice::errorString(), QIODevice::setErrorString()
  */
  void QAbstractFileEngine::setError(QFile::FileError error, const QString &errorString)
  {
      Q_D(QAbstractFileEngine);
      d->fileError = error;
      d->errorString = errorString;
  }
  
  QT_END_NAMESPACE
  