KSFileReader Class Reference

#include <ksfilereader.h>

Inheritance diagram for KSFileReader:

Signals
void	progressText (const QString &message)

Public Member Functions
	KSFileReader (QFile &file, qint64 maxLen=1024)
	KSFileReader (qint64 maxLen=1024)
bool	hasMoreLines () const
int	lineNumber () const
bool	open (const QString &fname)
bool	openFullPath (const QString &fname)
QString	readLine ()
void	setProgress (QString label, unsigned int lastLine, unsigned int numUpdates=10)
void	showProgress ()
Public Member Functions inherited from QObject
	QObject (QObject *parent)
QBindable< QString >	bindableObjectName ()
bool	blockSignals (bool block)
const QObjectList &	children () const const
QMetaObject::Connection	connect (const QObject *sender, const char *signal, const char *method, Qt::ConnectionType type) const const
void	deleteLater ()
void	destroyed (QObject *obj)
bool	disconnect (const char *signal, const QObject *receiver, const char *method) const const
bool	disconnect (const QObject *receiver, const char *method) const const
void	dumpObjectInfo () const const
void	dumpObjectTree () const const
QList< QByteArray >	dynamicPropertyNames () const const
virtual bool	event (QEvent *e)
virtual bool	eventFilter (QObject *watched, QEvent *event)
T	findChild (const QString &name, Qt::FindChildOptions options) const const
QList< T >	findChildren (const QRegularExpression &re, Qt::FindChildOptions options) const const
QList< T >	findChildren (const QString &name, Qt::FindChildOptions options) const const
QList< T >	findChildren (Qt::FindChildOptions options) const const
bool	inherits (const char *className) const const
void	installEventFilter (QObject *filterObj)
bool	isQuickItemType () const const
bool	isWidgetType () const const
bool	isWindowType () const const
void	killTimer (int id)
virtual const QMetaObject *	metaObject () const const
void	moveToThread (QThread *targetThread)
QString	objectName () const const
void	objectNameChanged (const QString &objectName)
QObject *	parent () const const
QVariant	property (const char *name) const const
	Q_CLASSINFO (Name, Value)
	Q_EMIT Q_EMIT
	Q_ENUM (...)
	Q_ENUM_NS (...)
	Q_ENUMS (...)
	Q_FLAG (...)
	Q_FLAG_NS (...)
	Q_FLAGS (...)
	Q_GADGET Q_GADGET
	Q_GADGET_EXPORT (EXPORT_MACRO)
	Q_INTERFACES (...)
	Q_INVOKABLE Q_INVOKABLE
	Q_MOC_INCLUDE Q_MOC_INCLUDE
	Q_NAMESPACE Q_NAMESPACE
	Q_NAMESPACE_EXPORT (EXPORT_MACRO)
	Q_OBJECT Q_OBJECT
	Q_PROPERTY (...)
	Q_REVISION Q_REVISION
	Q_SET_OBJECT_NAME (Object)
	Q_SIGNAL Q_SIGNAL
	Q_SIGNALS Q_SIGNALS
	Q_SLOT Q_SLOT
	Q_SLOTS Q_SLOTS
T	qobject_cast (const QObject *object)
T	qobject_cast (QObject *object)
	QT_NO_NARROWING_CONVERSIONS_IN_CONNECT QT_NO_NARROWING_CONVERSIONS_IN_CONNECT
void	removeEventFilter (QObject *obj)
void	setObjectName (const QString &name)
void	setObjectName (QAnyStringView name)
void	setParent (QObject *parent)
bool	setProperty (const char *name, const QVariant &value)
bool	setProperty (const char *name, QVariant &&value)
bool	signalsBlocked () const const
int	startTimer (int interval, Qt::TimerType timerType)
int	startTimer (std::chrono::milliseconds interval, Qt::TimerType timerType)
QThread *	thread () const const
Public Member Functions inherited from QTextStream
	QTextStream (const QByteArray &array, OpenMode openMode)
	QTextStream (FILE *fileHandle, OpenMode openMode)
	QTextStream (QByteArray *array, OpenMode openMode)
	QTextStream (QIODevice *device)
	QTextStream (QString *string, OpenMode openMode)
bool	atEnd () const const
bool	autoDetectUnicode () const const
QIODevice *	device () const const
QStringConverter::Encoding	encoding () const const
FieldAlignment	fieldAlignment () const const
int	fieldWidth () const const
void	flush ()
bool	generateByteOrderMark () const const
int	integerBase () const const
QLocale	locale () const const
NumberFlags	numberFlags () const const
QTextStream &	operator<< (char c)
QTextStream &	operator<< (char16_t c)
QTextStream &	operator<< (const char *string)
QTextStream &	operator<< (const QByteArray &array)
QTextStream &	operator<< (const QString &string)
QTextStream &	operator<< (const void *ptr)
QTextStream &	operator<< (double f)
QTextStream &	operator<< (float f)
QTextStream &	operator<< (int i)
QTextStream &	operator<< (long i)
QTextStream &	operator<< (QChar c)
QTextStream &	operator<< (QLatin1StringView string)
QTextStream &	operator<< (qlonglong i)
QTextStream &	operator<< (QStringView string)
QTextStream &	operator<< (qulonglong i)
QTextStream &	operator<< (short i)
QTextStream &	operator<< (unsigned int i)
QTextStream &	operator<< (unsigned long i)
QTextStream &	operator<< (unsigned short i)
QTextStream &	operator>> (char &c)
QTextStream &	operator>> (char *c)
QTextStream &	operator>> (char16_t &c)
QTextStream &	operator>> (double &f)
QTextStream &	operator>> (float &f)
QTextStream &	operator>> (int &i)
QTextStream &	operator>> (long &i)
QTextStream &	operator>> (QByteArray &array)
QTextStream &	operator>> (QChar &c)
QTextStream &	operator>> (qlonglong &i)
QTextStream &	operator>> (QString &str)
QTextStream &	operator>> (qulonglong &i)
QTextStream &	operator>> (short &i)
QTextStream &	operator>> (unsigned int &i)
QTextStream &	operator>> (unsigned long &i)
QTextStream &	operator>> (unsigned short &i)
QChar	padChar () const const
qint64	pos () const const
QTextStreamManipulator	qSetFieldWidth (int width)
QTextStreamManipulator	qSetPadChar (QChar ch)
QTextStreamManipulator	qSetRealNumberPrecision (int precision)
QString	read (qint64 maxlen)
QString	readAll ()
QString	readLine (qint64 maxlen)
bool	readLineInto (QString *line, qint64 maxlen)
RealNumberNotation	realNumberNotation () const const
int	realNumberPrecision () const const
void	reset ()
void	resetStatus ()
bool	seek (qint64 pos)
void	setAutoDetectUnicode (bool enabled)
void	setDevice (QIODevice *device)
void	setEncoding (QStringConverter::Encoding encoding)
void	setFieldAlignment (FieldAlignment mode)
void	setFieldWidth (int width)
void	setGenerateByteOrderMark (bool generate)
void	setIntegerBase (int base)
void	setLocale (const QLocale &locale)
void	setNumberFlags (NumberFlags flags)
void	setPadChar (QChar ch)
void	setRealNumberNotation (RealNumberNotation notation)
void	setRealNumberPrecision (int precision)
void	setStatus (Status status)
void	setString (QString *string, OpenMode openMode)
void	skipWhiteSpace ()
Status	status () const const
QString *	string () const const

Additional Inherited Members
Public Types inherited from QObject
typedef	QObjectList
Public Types inherited from QTextStream
enum	FieldAlignment
enum	NumberFlag
typedef	NumberFlags
enum	RealNumberNotation
enum	Status
Public Types inherited from QIODeviceBase
typedef	OpenMode
enum	OpenModeFlag
Properties inherited from QObject
	objectName
Static Public Member Functions inherited from QObject
QMetaObject::Connection	connect (const QObject *sender, const char *signal, const QObject *receiver, const char *method, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject *sender, PointerToMemberFunction signal, const QObject *context, Functor functor, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject *sender, PointerToMemberFunction signal, const QObject *receiver, PointerToMemberFunction method, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject *sender, PointerToMemberFunction signal, Functor functor)
bool	disconnect (const QMetaObject::Connection &connection)
bool	disconnect (const QObject *sender, const char *signal, const QObject *receiver, const char *method)
bool	disconnect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method)
bool	disconnect (const QObject *sender, PointerToMemberFunction signal, const QObject *receiver, PointerToMemberFunction method)
QString	tr (const char *sourceText, const char *disambiguation, int n)
Public Attributes inherited from QTextStream
	AlignAccountingStyle
	AlignCenter
	AlignLeft
	AlignRight
	FixedNotation
	ForcePoint
	ForceSign
	Ok
	ReadCorruptData
	ReadPastEnd
	ScientificNotation
	ShowBase
	SmartNotation
	UppercaseBase
	UppercaseDigits
	WriteFailed
Public Attributes inherited from QIODeviceBase
	Append
	ExistingOnly
	NewOnly
	NotOpen
	ReadOnly
	ReadWrite
	Text
	Truncate
	Unbuffered
	WriteOnly
Protected Member Functions inherited from QObject
virtual void	childEvent (QChildEvent *event)
virtual void	connectNotify (const QMetaMethod &signal)
virtual void	customEvent (QEvent *event)
virtual void	disconnectNotify (const QMetaMethod &signal)
bool	isSignalConnected (const QMetaMethod &signal) const const
int	receivers (const char *signal) const const
QObject *	sender () const const
int	senderSignalIndex () const const
virtual void	timerEvent (QTimerEvent *event)

Detailed Description

I totally rewrote this because the earlier scheme of reading all the lines of a file into a buffer before processing is actually extremely inefficient because it makes it impossible to interleave file reading and data processing which all modern computers can do.

It also force large data files to be split up into many smaller files which made dealing with the data much more difficult and made the code to read in the data needlessly complicated. A simple subclassing of QTextStream fixed all of the above problems (IMO).

I had added periodic progress reports based on line number to several parts of the code that read in large files. So I combined that duplicated code into one place which was naturally here. The progress code causes almost nothing extra to take place when reading a file that does not use it. The only thing extra is incrementing the line number. For files that you want to emit periodic progress reports, you call setProgress() once setting up the message to display and the intervals the message will be emitted. Then inside the loop you call showProgress(). This is an extra call in the read loop but it just does an integer compare and almost always returns. We could inline it to reduce the call overhead but I don't think it makes a bit of difference considering all of the processing that takes place when we read in a line from a data file.

NOTE: We no longer close the file like the previous version did. I've changed the code where this was assumed.

There are two ways to use this class. One is pass in a QFile& in the constructor which is included only for backward compatibility. The preferred way is to just instantiate KSFileReader with no parameters and then use the open( QString fname ) method to let this class handle the file opening which helps take unneeded complexity out of the calling classes. I didn't make a constructor with the filename in it because we need to be able to inform the caller of an error opening the file, hence the bool open(filename) method.

– James B. Bowlin

Definition at line 54 of file ksfilereader.h.

Constructor & Destructor Documentation

KSFileReader() [1/2]

KSFileReader::KSFileReader ( qint64 maxLen = 1024 )

explicit

this is the preferred constructor.

You can then use the open() method to let this class open the file for you.

Definition at line 21 of file ksfilereader.cpp.

KSFileReader() [2/2]

KSFileReader::KSFileReader ( QFile & file, qint64 maxLen = 1024 )

explicit

Constructor.

Parameters

file	is a previously opened (for reading) file.
maxLen	sets the maximum line length before wrapping. Setting this parameter should help efficiency. The little max-length.pl script will tell you the maximum line length of files.

Definition at line 25 of file ksfilereader.cpp.

Member Function Documentation

hasMoreLines()

bool KSFileReader::hasMoreLines ( ) const

inline

Returns

true if we are not yet at the end of the file. (I added this to be compatible with existing code.)

Definition at line 101 of file ksfilereader.h.

lineNumber()

int KSFileReader::lineNumber ( ) const

inline

returns the current line number

Definition at line 113 of file ksfilereader.h.

open()

bool KSFileReader::open

(

const QString &

fname

)

opens the file fname from the QStandardPaths::AppLocalDataLocation directory and uses that file for the QTextStream.

Parameters

fname

the name of the file to open

Returns

returns true on success. Prints an error message and returns false on failure.

Definition at line 40 of file ksfilereader.cpp.

openFullPath()

bool KSFileReader::openFullPath

(

const QString &

fname

)

opens the file with full path fname and uses that file for the QTextStream.

open() locates QStandardPaths::AppLocalDataLocation behind the scenes, so passing fname such that QString fname = KSPaths::locate(QStandardPaths::AppLocalDataLocation, "file_name" ); is equivalent

Parameters

fname

full path to directory + name of the file to open

Returns

returns true on success. Prints an error message and returns false on failure.

Definition at line 56 of file ksfilereader.cpp.

readLine()

QString KSFileReader::readLine ( )

inline

increments the line number and returns the next line from the file as a QString.

Definition at line 106 of file ksfilereader.h.

setProgress()

void KSFileReader::setProgress	(	QString	label,
		unsigned int	lastLine,
		unsigned int	numUpdates = 10 )

Prepares this instance to emit progress reports on how much of the file has been read (in percent).

Parameters

label	the label
lastLine	the number of lines to be read
numUpdates	the number of progress reports to send

Definition at line 73 of file ksfilereader.cpp.

showProgress()

void KSFileReader::showProgress

(

)

emits progress reports when required and updates bookkeeping for when to send the next report.

This might seem slow at first glance but almost all the time we are just doing an integer compare and returning. If you are worried about speed we can inline it. It could also safely be included in the readLine() method since m_targetLine is set to MAXUINT in the constructor.

Definition at line 85 of file ksfilereader.cpp.

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The documentation for this class was generated from the following files:

• ksfilereader.h
• ksfilereader.cpp