qabstractfileengine.cpp

奇趣公司比较新的qt/emd版本

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 4.3
    \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:

    \code
    QAbstractFileEngineIterator *
    CustomFileEngine::beginEntryList(QDir::Filters filters, const QStringList &filterNames)
    {
        return new CustomFileEngineIterator(filters, filterNames);
    }
    \endcode

    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 virual 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 interator that returns each of
    three fixed entries in sequence.

    \code
    class CustomIterator : public QAbstractFileEngineIterator
    {
    public:
        CustomIterator(const QStringList &nameFilters, QDir::Filters filters)
            : QAbstractFileEngineIterator(nameFilters, filters), index(0)
        {