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)
	Constructor for function which uses unnamed parameters. More...

	Function (const QString &fnname, int params, const QStringList &groups, const QString &helpText=QString(), bool usesGeometry=false, const QStringList &referencedColumns=QStringList(), bool lazyEval=false, bool handlesNull=false, bool isContextual=false)
	Constructor for function which uses unnamed parameters and group list. More...

	Function (const QString &fnname, const ParameterList &params, const QString &group, const QString &helpText=QString(), bool usesGeometry=false, const QStringList &referencedColumns=QStringList(), bool lazyEval=false, bool handlesNull=false, bool isContextual=false)
	Constructor for function which uses named parameter list. More...

	Function (const QString &fnname, const ParameterList &params, const QStringList &groups, const QString &helpText=QString(), bool usesGeometry=false, const QStringList &referencedColumns=QStringList(), bool lazyEval=false, bool handlesNull=false, bool isContextual=false)
	Constructor for function which uses named parameter list and group list. More...

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 () const
	Returns the first group which the function belongs to. More...

QStringList	groups () const
	Returns a list of the groups the function belongs to. More...

virtual bool	handlesNull () const

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

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

virtual bool	isDeprecated () const
	Returns true if the function is deprecated and should not be presented as a valid option to users in expression builders. More...

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

int	minParams () const
	The mininum number of parameters this function takes. More...

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

bool	operator== (const Function &other) const

const ParameterList &	parameters () const
	Returns the list of named parameters for the function, if set. More...

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

virtual QStringList	referencedColumns () const

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

Detailed Description

A abstract base class for defining QgsExpression functions.

Definition at line 516 of file qgsexpression.h.

Constructor & Destructor Documentation

◆ Function() [1/4]

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

Constructor for function which uses unnamed parameters.

Definition at line 521 of file qgsexpression.h.

◆ Function() [2/4]

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

inline

Constructor for function which uses unnamed parameters and group list.

Note: added in QGIS 2.18

Definition at line 545 of file qgsexpression.h.

◆ Function() [3/4]

QgsExpression::Function::Function	(	const QString &	fnname,
		const ParameterList &	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

Constructor for function which uses named parameter list.

Note: added in QGIS 2.16

Definition at line 569 of file qgsexpression.h.

◆ Function() [4/4]

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

inline

Constructor for function which uses named parameter list and group list.

Note: added in QGIS 2.18

Definition at line 593 of file qgsexpression.h.

◆ ~Function()

virtual QgsExpression::Function::~Function ( )

inlinevirtual

Definition at line 615 of file qgsexpression.h.

Member Function Documentation

◆ aliases()

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 652 of file qgsexpression.h.

◆ func() [1/2]

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 5264 of file qgsexpression.cpp.

◆ func() [2/2]

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 5271 of file qgsexpression.cpp.

◆ group()

QString QgsExpression::Function::group ( ) const

inline

Returns the first group which the function belongs to.

Note: consider using groups() instead, as some functions naturally belong in multiple groups

Definition at line 676 of file qgsexpression.h.

◆ groups()

QStringList QgsExpression::Function::groups ( ) const

inline

Returns a list of the groups the function belongs to.

Note: added in QGIS 2.18

See also: group()

Definition at line 682 of file qgsexpression.h.

◆ handlesNull()

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

inlinevirtual

Definition at line 709 of file qgsexpression.h.

◆ helptext()

const QString QgsExpression::Function::helptext ( ) const

inline

The help text for the function.

Definition at line 686 of file qgsexpression.h.

◆ isContextual()

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 665 of file qgsexpression.h.

◆ isDeprecated()

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

inlinevirtual

Returns true if the function is deprecated and should not be presented as a valid option to users in expression builders.

Note: added in QGIS 2.18

Definition at line 671 of file qgsexpression.h.

◆ lazyEval()

bool QgsExpression::Function::lazyEval ( ) const

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 658 of file qgsexpression.h.

◆ minParams()

int QgsExpression::Function::minParams ( ) const

inline

The mininum number of parameters this function takes.

Definition at line 624 of file qgsexpression.h.

◆ name()

QString QgsExpression::Function::name ( ) const

inline

The name of the function.

Definition at line 618 of file qgsexpression.h.

◆ operator==()

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

inline

Definition at line 701 of file qgsexpression.h.

◆ parameters()

const ParameterList& QgsExpression::Function::parameters ( ) const

inline

Returns the list of named parameters for the function, if set.

Note: added in QGIS 2.16

Definition at line 641 of file qgsexpression.h.

◆ params()

int QgsExpression::Function::params ( ) const

inline

The number of parameters this function takes.

Definition at line 621 of file qgsexpression.h.

◆ referencedColumns()

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

inlinevirtual

Definition at line 660 of file qgsexpression.h.

◆ usesgeometry()

bool QgsExpression::Function::usesgeometry ( ) const

inline

Does this function use a geometry object.

Definition at line 645 of file qgsexpression.h.

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

/tmp/buildd/qgis-2.18.21+99unstable/src/core/qgsexpression.h
/tmp/buildd/qgis-2.18.21+99unstable/src/core/qgsexpression.cpp

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ Function() [1/4]

◆ Function() [2/4]

◆ Function() [3/4]

◆ Function() [4/4]

◆ ~Function()

Member Function Documentation

◆ aliases()

◆ func() [1/2]

◆ func() [2/2]

◆ group()

◆ groups()

◆ handlesNull()

◆ helptext()

◆ isContextual()

◆ isDeprecated()

◆ lazyEval()

◆ minParams()

◆ name()

◆ operator==()

◆ parameters()

◆ params()

◆ referencedColumns()

◆ usesgeometry()