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QFileEngine Class Reference

The QFileEngine class provides an abstraction for accessing the filesystem. More...

#include <QFileEngine>

Inherits QIOEngine.

Note: All the functions in this class are reentrant.

List of all members.

Public Types

Public Functions

Static Public Members

Protected Functions


Detailed Description

The QFileEngine class provides an abstraction for accessing the filesystem.

The QDir, QFile, and QFileInfo classes all make use of a QFileEngine internally. If you create your own QFileEngine subclass (and register it with Qt by creating a QFileEngineHandler subclass), your file engine will be used when the path is one that your file engine handles.

A QFileEngine 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(), entryList(), and isRoot() functions are applicable. In all cases the caseSensitive(), isRelativePath(), fileFlags(), ownerId(), owner(), and fileTime() functions are applicable.

A QFileEngine subclass can be created to do syncronous network I/O based file system operations, local file system operations, or to operate as a resource system to access file based resources.

See also QFileEngineHandler and setFileName().


Member Type Documentation

enum QFileEngine::FileInfo

The permissions and types of a file, suitable for OR'ing together.

QFileEngine::ReadOwnerPermThe owner of the file has permission to read it.
QFileEngine::WriteOwnerPermThe owner of the file has permission to write to it.
QFileEngine::ExeOwnerPermThe owner of the file has permission to execute it.
QFileEngine::ReadUserPermThe current user has permission to read the file.
QFileEngine::WriteUserPermThe current user has permission to write to the file.
QFileEngine::ExeUserPermThe current user has permission to execute the file.
QFileEngine::ReadGroupPermMembers of the current user's group have permission to read the file.
QFileEngine::WriteGroupPermMembers of the current user's group have permission to write to the file.
QFileEngine::ExeGroupPermMembers of the current user's group have permission to execute the file.
QFileEngine::ReadOtherPermAll users have permission to read the file.
QFileEngine::WriteOtherPermAll users have permission to write to the file.
QFileEngine::ExeOtherPermAll users have permission to execute the file.
QFileEngine::LinkTypeThe file is a link to another file (or link) in the file system (i.e. not a file or directory).
QFileEngine::FileTypeThe file is a regular file to the file system (i.e. not a link or directory)
QFileEngine::DirectoryTypeThe file is a directory in the file system (i.e. not a link or file).
QFileEngine::HiddenFlagThe file is hidden.
QFileEngine::ExistsFlagThe file actually exists in the file system.

See also fileFlags() and setFileName().

enum QFileEngine::FileName

These values are used to request a file name in a particular format.

QFileEngine::DefaultNameThe same filename that was passed to the QFileEngine.
QFileEngine::BaseNameThe name of the file excluding the path.
QFileEngine::PathNameThe path to the file excluding the BaseName.
QFileEngine::AbsoluteNameThe absolute path to the file (including the BaseName).
QFileEngine::AbsolutePathNameThe absolute path to the file (excluding the BaseName).
QFileEngine::LinkNameThe full file name of the file that this file is a link to. (This will be empty if this file is not a link.)
QFileEngine::CanonicalNameOften very similar to LinkName will return the true path to the file

See also fileName() and setFileName().

enum QFileEngine::FileOwner

QFileEngine::OwnerUserThe user who owns the file.
QFileEngine::OwnerGroupThe group who owns the file.

See also owner(), ownerId(), and setFileName().

enum QFileEngine::FileTime

These are used by the fileTime() function.

QFileEngine::CreationTimeWhen the file was created.
QFileEngine::ModificationTimeWhen the file was most recently modified.
QFileEngine::AccessTimeWhen the file was most recently accessed (e.g. read or written to).

See also setFileName().


Member Function Documentation

QFileEngine::QFileEngine ()   [protected]

Constructs a new QFileEngine that does not refer to any file or directory.

See also setFileName().

QFileEngine::~QFileEngine ()   [virtual]

Destroys the QFileEngine.

bool QFileEngine::caseSensitive () const   [pure virtual]

Should return true if the underlying file system is case-sensitive; otherwise return false.

This virtual function must be reimplemented by all subclasses.

QFileEngine * QFileEngine::createFileEngine ( const QString & file )   [static]

Creates a new QFileEngine instance for the given file. This function will always return a valid QFileEngine. The default file engine that is created if no custom file engine handles files of file's path is one that operates on the local file system.

QStringList QFileEngine::entryList ( int filterSpec, const QStringList & filters ) const   [pure virtual]

Requests that a list of all the files matching the filters list based on the filterSpec 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.

See also setFileName().

uint QFileEngine::fileFlags ( uint type = FileInfoAll ) const   [pure virtual]

This function should return the set of OR'd QFileEngine::FileInfo members that are true for the file engine's file, and that are in the type's OR'd members.

In your reimplementation you can use the type argument as an optimization hint and only return the OR'd set of members that are true and that match those in type; in other words you can ignore any members not mentioned in type, thus avoiding some potentially expensive lookups or system calls.

This virtual function must be reimplemented by all subclasses.

See also setFileName() and FileInfo.

QString QFileEngine::fileName ( FileName file = DefaultName ) const   [pure virtual]

Return the file engine's current file name in the format specified by file.

If you don't handle some FileName possibilities, return the file name set in setFileName() when an unhandled format is requested.

This virtual function must be reimplemented by all subclasses.

See also setFileName() and FileName.

QDateTime QFileEngine::fileTime ( FileTime time ) const   [pure virtual]

If time is CreationTime, return when the file was created. If time is ModificationTime, return when the file was most recently modified. If time is 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.

See also setFileName(), QDateTime, QDateTime::isValid(), and FileTime.

bool QFileEngine::isRelativePath () const   [pure virtual]

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.

See also setFileName().

bool QFileEngine::isRoot () const   [pure virtual]

Return true if the file referred to by this file engine is the root of the file system; otherwise return false.

This virtual function must be reimplemented by all subclasses.

See also setFileName().

bool QFileEngine::mkdir ( const QString & dirName, QDir::Recursion recurse ) const   [pure virtual]

Requests that the directory dirName be created. If recurse is QDir::Recursive then any sub-directories in dirName that don't exist must be created. If recurse is QDir::NonRecursive then any sub-directories in 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.

See also setFileName(), rmdir(), and isRelativePath().

QString QFileEngine::owner ( FileOwner owner ) const   [pure virtual]

If owner is OwnerUser return the name of the user who owns the file. If owner is 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.

See also ownerId(), setFileName(), and FileOwner.

uint QFileEngine::ownerId ( FileOwner owner ) const   [pure virtual]

If owner is OwnerUser return the ID of the user who owns the file. If owner is 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.

See also owner(), setFileName(), and FileOwner.

bool QFileEngine::remove ()   [pure virtual]

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.

See also setFileName() and rmdir().

bool QFileEngine::rename ( const QString & newName )   [pure virtual]

Requests that the file be renamed to newName in the file system. If the operation succeeds return true; otherwise return false.

This virtual function must be reimplemented by all subclasses.

See also setFileName().

bool QFileEngine::rmdir ( const QString & dirName, QDir::Recursion recurse ) const   [pure virtual]

Requests that the directory dirName is deleted from the file system. When recurse is QDir::Recursive then any empty sub-directories in dirName must also be deleted. If recurse is QDir::NonRecursive then only dirName 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.

See also setFileName(), remove(), mkdir(), and isRelativePath().

void QFileEngine::setFileName ( const QString & file )   [pure virtual]

Sets the file engine's file name to 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.

See also rename().


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Qt 4.0.0-tp1