A abstract base class for defining QgsExpression functions. More...

#include <qgsexpression.h>

Inheritance diagram for QgsExpression::Function:

Public Member Functions
	Function (const QString &fnname, int params, const QString &group, const QString &helpText=QString(), bool usesGeometry=false, const QStringList &referencedColumns=QStringList(), bool lazyEval=false, bool handlesNull=false, bool isContextual=false)

virtual	~Function ()

virtual QStringList	aliases () const
	Returns a list of possible aliases for the function. More...

virtual Q_DECL_DEPRECATED QVariant	func (const QVariantList &, const QgsFeature , QgsExpression )

virtual QVariant	func (const QVariantList &values, const QgsExpressionContext context, QgsExpression parent)
	Returns result of evaluating the function. More...

QString	group ()
	The group the function belongs to. More...

virtual bool	handlesNull () const

const QString	helptext ()
	The help text for the function. More...

bool	isContextual () const
	Returns whether the function is only available if provided by a QgsExpressionContext object. More...

bool	lazyEval ()
	True if this function should use lazy evaluation. More...

QString	name ()
	The name of the function. More...

bool	operator== (const Function &other) const

int	params ()
	The number of parameters this function takes. More...

virtual QStringList	referencedColumns () const

bool	usesgeometry ()
	Does this function use a geometry object. More...

Detailed Description

A abstract base class for defining QgsExpression functions.

Definition at line 436 of file qgsexpression.h.

Constructor & Destructor Documentation

QgsExpression::Function::Function	(	const QString &	fnname,
		int	params,
		const QString &	group,
		const QString &	helpText = `QString()`,
		bool	usesGeometry = `false`,
		const QStringList &	referencedColumns = `QStringList()`,
		bool	lazyEval = `false`,
		bool	handlesNull = `false`,
		bool	isContextual = `false`
	)

inline

Definition at line 439 of file qgsexpression.h.

virtual QgsExpression::Function::~Function ( )

inlinevirtual

Definition at line 459 of file qgsexpression.h.

Member Function Documentation

virtual QStringList QgsExpression::Function::aliases ( ) const

inlinevirtual

Returns a list of possible aliases for the function.

These include other permissible names for the function, eg deprecated names.

Returns: list of known aliases

Note: added in QGIS 2.9

Reimplemented in QgsExpression::StaticFunction.

Definition at line 473 of file qgsexpression.h.

QVariant QgsExpression::Function::func	(	const QVariantList &	values,
		const QgsFeature *	feature,
		QgsExpression *	parent
	)

virtual

Deprecated:: Use QgsExpressionContext variant instead

Reimplemented in QgsExpression::StaticFunction.

Definition at line 4676 of file qgsexpression.cpp.

QVariant QgsExpression::Function::func	(	const QVariantList &	values,
		const QgsExpressionContext *	context,
		QgsExpression *	parent
	)

virtual

Returns result of evaluating the function.

Parameters

values	list of values passed to the function
context	context expression is being evaluated against
parent	parent expression

Returns: result of function

Note: named funcV2 in Python bindings. Will be renamed to func to replace deprecated method in QGIS 3.0.

Reimplemented in QgsExpression::StaticFunction, and QgsScopedExpressionFunction.

Definition at line 4683 of file qgsexpression.cpp.

QString QgsExpression::Function::group ( )

inline

The group the function belongs to.

Definition at line 488 of file qgsexpression.h.

virtual bool QgsExpression::Function::handlesNull ( ) const

inlinevirtual

Definition at line 513 of file qgsexpression.h.

const QString QgsExpression::Function::helptext ( )

inline

The help text for the function.

Definition at line 490 of file qgsexpression.h.

bool QgsExpression::Function::isContextual ( ) const

inline

Returns whether the function is only available if provided by a QgsExpressionContext object.

Note: added in QGIS 2.12

Definition at line 485 of file qgsexpression.h.

bool QgsExpression::Function::lazyEval ( )

inline

True if this function should use lazy evaluation.

Lazy evaluation functions take QgsExpression::Node objects rather than the node results when called. You can use node->eval(parent, feature) to evaluate the node and return the result Functions are non lazy default and will be given the node return value when called

Definition at line 478 of file qgsexpression.h.

QString QgsExpression::Function::name ( )

inline

The name of the function.

Definition at line 462 of file qgsexpression.h.

bool QgsExpression::Function::operator== ( const Function & other ) const

inline

Definition at line 505 of file qgsexpression.h.

int QgsExpression::Function::params ( )

inline

The number of parameters this function takes.

Definition at line 464 of file qgsexpression.h.

virtual QStringList QgsExpression::Function::referencedColumns ( ) const

inlinevirtual

Definition at line 480 of file qgsexpression.h.

bool QgsExpression::Function::usesgeometry ( )

inline

Does this function use a geometry object.

Definition at line 466 of file qgsexpression.h.

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

/tmp/buildd/qgis-2.14.0+99unstable/src/core/qgsexpression.h
/tmp/buildd/qgis-2.14.0+99unstable/src/core/qgsexpression.cpp

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation