Class for parsing and evaluation of expressions (formerly called "search strings"). More...

#include <qgsexpression.h>

Collaboration diagram for QgsExpression:

Classes
class	Function
	A abstract base class for defining QgsExpression functions. More...
class	Interval
class	Node
class	NodeBinaryOperator
class	NodeColumnRef
class	NodeCondition
class	NodeFunction
class	NodeInOperator
class	NodeList
class	NodeLiteral
class	NodeUnaryOperator
class	StaticFunction
class	Visitor
	support for visitor pattern - algorithms dealing with the expressions may be implemented without modifying the Node classes More...
class	WhenThen
Public Types
enum	BinaryOperator { boOr, boAnd, boEQ, boNE, boLE, boGE, boLT, boGT, boRegexp, boLike, boNotLike, boILike, boNotILike, boIs, boIsNot, boPlus, boMinus, boMul, boDiv, boMod, boPow, boConcat }
typedef QVariant(*	FcnEval )(const QVariantList &values, const QgsFeature f, QgsExpression parent)
enum	NodeType { ntUnaryOperator, ntBinaryOperator, ntInOperator, ntFunction, ntLiteral, ntColumnRef, ntCondition }
enum	SpatialOperator { soBbox, soIntersects, soContains, soCrosses, soEquals, soDisjoint, soOverlaps, soTouches, soWithin }
enum	UnaryOperator { uoNot, uoMinus }
typedef QList< WhenThen * >	WhenThenList
Public Member Functions
	QgsExpression (const QString &expr)
	~QgsExpression ()
void	acceptVisitor (Visitor &v) const
	entry function for the visitor pattern
int	currentRowNumber ()
	Return the number used for $rownum special column.
QString	dump () const
	Return the parsed expression as a string - useful for debugging.
QString	evalErrorString () const
	Returns evaluation error.
QVariant	evaluate (const QgsFeature *f=NULL)
	Evaluate the feature and return the result.
QVariant	evaluate (const QgsFeature &f)
	Evaluate the feature and return the result.
QVariant	evaluate (const QgsFeature *f, const QgsFields &fields)
	Evaluate the feature and return the result.
QVariant	evaluate (const QgsFeature &f, const QgsFields &fields)
	Evaluate the feature and return the result.
const QString &	expression () const
QgsDistanceArea *	geomCalculator ()
	Return calculator used for distance and area calculations (used by internal functions)
bool	hasEvalError () const
	Returns true if an error occurred when evaluating last input.
bool	hasParserError () const
	Returns true if an error occurred when parsing the input expression.
bool	needsGeometry ()
	Returns true if the expression uses feature geometry for some computation.
QString	parserErrorString () const
	Returns parser error.
bool	prepare (const QgsFields &fields)
	Get the expression ready for evaluation - find out column indexes.
QStringList	referencedColumns ()
	Get list of columns referenced by the expression.
const Node *	rootNode () const
	Returns root node of the expression. Root node is null is parsing has failed.
int	scale ()
void	setCurrentRowNumber (int rowNumber)
	Set the number for $rownum special column.
void	setEvalErrorString (QString str)
	Set evaluation error (used internally by evaluation functions)
void	setGeomCalculator (QgsDistanceArea &calc)
	Sets the geometry calculator used in evaluation of expressions,.
void	setScale (double scale)
Static Public Member Functions
static const QStringList &	BuiltinFunctions ()
static int	functionCount ()
	Returns the number of functions defined in the parser.
static int	functionIndex (QString name)
static const QList< Function * > &	Functions ()
static QString	group (QString group)
static QString	helptext (QString name)
static bool	isFunctionName (QString name)
static QString	quotedColumnRef (QString name)
	return quoted column reference (in double quotes)
static QString	quotedString (QString text)
	return quoted string (in single quotes)
static bool	registerFunction (Function *function)
static QString	replaceExpressionText (QString action, QgsFeature feat, QgsVectorLayer layer, const QMap< QString, QVariant > *substitutionMap=0)
	This function currently replaces each expression between [% and %] in the string with the result of its evaluation on the feature passed as argument.
static QString	replaceExpressionText (QString action, QgsFeature &feat, QgsVectorLayer layer, const QMap< QString, QVariant > substitutionMap=0)
static void	setSpecialColumn (const QString &name, QVariant value)
	Assign a special column.
static QVariant	specialColumn (const QString &name)
	Return the value of the given special column or a null QVariant if undefined.
static QList< Function * >	specialColumns ()
	Returns a list of special Column definitions.
static bool	unregisterFunction (QString name)
static void	unsetSpecialColumn (const QString &name)
	Unset a special column.
Static Public Attributes
static const char *	BinaryOperatorText []
static QStringList	gmBuiltinFunctions
static QList< Function * >	gmFunctions
static const char *	UnaryOperatorText []
Protected Member Functions
	QgsExpression ()
void	initGeomCalculator ()
Static Protected Member Functions
static void	initFunctionHelp ()
Protected Attributes
QgsDistanceArea	mCalc
QString	mEvalErrorString
QString	mExpression
QString	mParserErrorString
Node *	mRootNode
int	mRowNumber
double	mScale
Static Protected Attributes
static QHash< QString, QString >	gFunctionHelpTexts
static QHash< QString, QString >	gGroups
static QMap< QString, QVariant >	gmSpecialColumns
Friends
class	QgsOgcUtils

Detailed Description

Class for parsing and evaluation of expressions (formerly called "search strings").

The expressions try to follow both syntax and semantics of SQL expressions.

Usage:

QgsExpression exp("gid*2 > 10 and type not in ('D','F')); if (exp.hasParserError()) { show error message with parserErrorString() and exit } QVariant result = exp.evaluate(feature, fields); if (exp.hasEvalError()) { show error message with evalErrorString() } else { examine the result }

Possible QVariant value types:

invalid (null)
int
double
string
geometry

Similarly to SQL, this class supports three-value logic: true/false/unknown. Unknown value may be a result of operations with missing data (NULL). Please note that NULL is different value than zero or an empty string. For example 3 > NULL returns unknown.

There is no special (three-value) 'boolean' type: true/false is represented as 1/0 integer, unknown value is represented the same way as NULL values: invalid QVariant.

For better performance with many evaluations you may first call prepare(fields) function to find out indices of columns and then repeatedly call evaluate(feature).

Type conversion: operators and functions that expect arguments to be of particular type automatically convert the arguments to that type, e.g. sin('2.1') will convert the argument to a double, length(123) will first convert the number to a string. Explicit conversion can be achieved with toint, toreal, tostring functions. If implicit or explicit conversion is invalid, the evaluation returns an error. Comparison operators do numeric comparison in case both operators are numeric (int/double) or they can be converted to numeric types.

Arithmetic operators do integer arithmetics if both operands are integer. That is 2+2 yields integer 4, but 2.0+2 returns real number 4.0. There are also two versions of division and modulo operators: 1.0/2 returns 0.5 while 1/2 returns 0.

Note:: added in 2.0

Definition at line 88 of file qgsexpression.h.

Member Typedef Documentation

typedef QVariant( * QgsExpression::FcnEval)(const QVariantList &values, const QgsFeature *f, QgsExpression *parent)

Definition at line 234 of file qgsexpression.h.

typedef QList<WhenThen*> QgsExpression::WhenThenList

Definition at line 555 of file qgsexpression.h.

Member Enumeration Documentation

enum QgsExpression::BinaryOperator

Enumerator:

boOr
boAnd
boEQ
boNE
boLE
boGE
boLT
boGT
boRegexp
boLike
boNotLike
boILike
boNotILike
boIs
boIsNot
boPlus
boMinus
boMul
boDiv
boMod
boPow
boConcat

Definition at line 186 of file qgsexpression.h.

enum QgsExpression::NodeType

Enumerator:

ntUnaryOperator
ntBinaryOperator
ntInOperator
ntFunction
ntLiteral
ntColumnRef
ntCondition

Definition at line 323 of file qgsexpression.h.

enum QgsExpression::SpatialOperator

Enumerator:

soBbox
soIntersects
soContains
soCrosses
soEquals
soDisjoint
soOverlaps
soTouches
soWithin

Definition at line 218 of file qgsexpression.h.

enum QgsExpression::UnaryOperator

Enumerator:

uoNot
uoMinus

Definition at line 181 of file qgsexpression.h.

Constructor & Destructor Documentation

QgsExpression::QgsExpression ( const QString & expr )

Definition at line 1611 of file qgsexpression.cpp.

References initGeomCalculator(), mExpression, mParserErrorString, mRootNode, and parseExpression().

QgsExpression::~QgsExpression ( )

Definition at line 1627 of file qgsexpression.cpp.

References mRootNode.

QgsExpression::QgsExpression ( ) [inline, protected]

Definition at line 602 of file qgsexpression.h.

Member Function Documentation

void QgsExpression::acceptVisitor ( QgsExpression::Visitor & v ) const

entry function for the visitor pattern

Definition at line 1719 of file qgsexpression.cpp.

References QgsExpression::Node::accept(), and mRootNode.

const QStringList & QgsExpression::BuiltinFunctions ( ) [static]

Definition at line 1398 of file qgsexpression.cpp.

References gmBuiltinFunctions.

Referenced by unregisterFunction().

int QgsExpression::currentRowNumber ( ) [inline]

Return the number used for $rownum special column.

Definition at line 140 of file qgsexpression.h.

Referenced by fcnRowNumber().

QString QgsExpression::dump ( ) const

Return the parsed expression as a string - useful for debugging.

Definition at line 1711 of file qgsexpression.cpp.

References QgsExpression::Node::dump(), mRootNode, and tr.

Referenced by QgsRuleBasedRendererV2::Rule::createFromSld(), QgsSymbolLayerV2Utils::functionFromSldElement(), and QgsEllipseSymbolLayerV2::writeSldMarker().

QString QgsExpression::evalErrorString ( ) const [inline]

Returns evaluation error.

Definition at line 133 of file qgsexpression.h.

Referenced by QgsSearchQueryBuilder::countRecords(), QgsPalLayerSettings::dataDefinedValue(), QgsAttributeAction::expandAction(), QgsExpressionBuilderWidget::on_txtExpressionString_textChanged(), QgsDataDefined::prepareExpression(), QgsPalLabeling::prepareLayer(), QgsAttributeDialog::QgsAttributeDialog(), QgsPalLayerSettings::registerFeature(), and replaceExpressionText().

QVariant QgsExpression::evaluate ( const QgsFeature * f = NULL )

Evaluate the feature and return the result.

Note:: prepare() should be called before calling this method

Definition at line 1688 of file qgsexpression.cpp.

References QgsExpression::Node::eval(), mEvalErrorString, mRootNode, and tr.

Referenced by QgsSVGFillSymbolLayer::applyDataDefinedSettings(), QgsLinePatternFillSymbolLayer::applyDataDefinedSettings(), QgsPointPatternFillSymbolLayer::applyDataDefinedSettings(), QgsSimpleFillSymbolLayerV2::applyDataDefinedSymbology(), QgsSimpleLineSymbolLayerV2::applyDataDefinedSymbology(), QgsSearchQueryBuilder::countRecords(), QgsAttributeEditor::createAttributeEditor(), QgsFeatureListModel::data(), QgsPalLayerSettings::dataDefinedValue(), evaluate(), QgsAttributeAction::expandAction(), QgsAttributeTableModel::loadAttributes(), QgsMarkerSymbolLayerV2::markerOffset(), QgsExpressionSelectionDialog::on_mActionAddToSelection_triggered(), QgsExpressionSelectionDialog::on_mActionRemoveFromSelection_triggered(), QgsExpressionSelectionDialog::on_mActionSelect_triggered(), QgsExpressionSelectionDialog::on_mActionSelectInstersect_triggered(), QgsExpressionBuilderWidget::on_txtExpressionString_textChanged(), QgsEllipseSymbolLayerV2::preparePath(), QgsAttributeDialog::QgsAttributeDialog(), QgsPalLayerSettings::registerFeature(), QgsEllipseSymbolLayerV2::renderPoint(), QgsSimpleMarkerSymbolLayerV2::renderPoint(), QgsSvgMarkerSymbolLayerV2::renderPoint(), QgsMarkerLineSymbolLayerV2::renderPolyline(), QgsMarkerLineSymbolLayerV2::renderPolylineInterval(), and replaceExpressionText().

QVariant QgsExpression::evaluate ( const QgsFeature & f ) [inline]

Evaluate the feature and return the result.

Note:: prepare() should be called before calling this method

Definition at line 120 of file qgsexpression.h.

References evaluate().

Referenced by evaluate().

QVariant QgsExpression::evaluate	(	const QgsFeature *	f,
		const QgsFields &	fields
	)

Evaluate the feature and return the result.

Note:: this method does not expect that prepare() has been called on this instance

Definition at line 1700 of file qgsexpression.cpp.

References evaluate(), and prepare().

QVariant QgsExpression::evaluate	(	const QgsFeature &	f,
		const QgsFields &	fields
	)		`[inline]`

Evaluate the feature and return the result.

Note:: this method does not expect that prepare() has been called on this instance

Definition at line 128 of file qgsexpression.h.

References evaluate().

Referenced by evaluate().

const QString& QgsExpression::expression ( ) const [inline]

Definition at line 153 of file qgsexpression.h.

Referenced by QgsSymbolLayerV2::dataDefinedPropertyString(), and QgsFeatureListModel::displayExpression().

int QgsExpression::functionCount ( ) [static]

Returns the number of functions defined in the parser.

Returns:: The number of function defined in the parser.

Definition at line 1605 of file qgsexpression.cpp.

References Functions().

Referenced by functionIndex(), and QgsExpressionBuilderWidget::QgsExpressionBuilderWidget().

int QgsExpression::functionIndex ( QString name ) [static]

Definition at line 1594 of file qgsexpression.cpp.

References functionCount(), and Functions().

Referenced by isFunctionName(), QgsOgcUtils::nodeSpatialOperatorFromOgcFilter(), registerFunction(), setSpecialColumn(), specialColumn(), and unregisterFunction().

const QList< QgsExpression::Function * > & QgsExpression::Functions ( ) [static]

Definition at line 1430 of file qgsexpression.cpp.

References fcnAbs(), fcnAcos(), fcnAge(), fcnAsin(), fcnAtan(), fcnAtan2(), fcnBbox(), fcnBuffer(), fcnCeil(), fcnCentroid(), fcnClamp(), fcnCoalesce(), fcnColorCmyk(), fcnColorHsl(), fcnColorHsv(), fcnColorRgb(), fcnCombine(), fcnConcat(), fcnContains(), fcnConvexHull(), fcnCos(), fcnCrosses(), fcnDay(), fcnDifference(), fcnDisjoint(), fcnDistance(), fcnExp(), fcnExpScale(), fcnFeatureId(), fcnFloor(), fcnFormatDate(), fcnFormatNumber(), fcnFormatString(), fcnGeomArea(), fcnGeometry(), fcnGeomFromGML(), fcnGeomFromWKT(), fcnGeomLength(), fcnGeomPerimeter(), fcnGeomToWKT(), fcnHour(), fcnIntersection(), fcnIntersects(), fcnLeft(), fcnLength(), fcnLinearScale(), fcnLn(), fcnLog(), fcnLog10(), fcnLower(), fcnLPad(), fcnMax(), fcnMin(), fcnMinute(), fcnMonth(), fcnNow(), fcnOverlaps(), fcnPi(), fcnRampColor(), fcnRegexpMatch(), fcnRegexpReplace(), fcnRegexpSubstr(), fcnReplace(), fcnRight(), fcnRnd(), fcnRndF(), fcnRound(), fcnRowNumber(), fcnRPad(), fcnScale(), fcnSeconds(), fcnSin(), fcnSpecialColumn(), fcnSqrt(), fcnStrpos(), fcnSubstr(), fcnSymDifference(), fcnTan(), fcnTitle(), fcnToDate(), fcnToDateTime(), fcnToInt(), fcnToInterval(), fcnToReal(), fcnToString(), fcnToTime(), fcnTouches(), fcnTrim(), fcnUpper(), fcnWeek(), fcnWithin(), fcnX(), fcnXat(), fcnY(), fcnYat(), fcnYear(), fncColorCmyka(), fncColorHsla(), fncColorHsva(), fncColorRgba(), and gmFunctions.

Referenced by QgsExpression::NodeFunction::dump(), QgsExpression::NodeFunction::eval(), QgsOgcUtils::expressionFunctionToOgcFilter(), functionCount(), functionIndex(), isGeometryColumn(), QgsOgcUtils::nodeFunctionFromOgcFilter(), and QgsExpressionBuilderWidget::QgsExpressionBuilderWidget().

QgsDistanceArea* QgsExpression::geomCalculator ( ) [inline]

Return calculator used for distance and area calculations (used by internal functions)

Definition at line 160 of file qgsexpression.h.

Referenced by fcnGeomArea(), fcnGeomLength(), and fcnGeomPerimeter().

QString QgsExpression::group ( QString group ) [static]

Definition at line 2367 of file qgsexpression.cpp.

References gGroups, and tr.

Referenced by QgsExpressionBuilderWidget::registerItem().

bool QgsExpression::hasEvalError ( ) const [inline]

Returns true if an error occurred when evaluating last input.

Definition at line 131 of file qgsexpression.h.

Referenced by QgsSearchQueryBuilder::countRecords(), QgsPalLayerSettings::dataDefinedValue(), QgsAttributeAction::expandAction(), QgsExpressionBuilderWidget::on_txtExpressionString_textChanged(), QgsDataDefined::prepareExpression(), QgsPalLabeling::prepareLayer(), QgsAttributeDialog::QgsAttributeDialog(), QgsPalLayerSettings::registerFeature(), and replaceExpressionText().

bool QgsExpression::hasParserError ( ) const [inline]

Returns true if an error occurred when parsing the input expression.

Definition at line 95 of file qgsexpression.h.

Referenced by QgsDataDefinedButton::aboutToShowMenu(), QgsSearchQueryBuilder::countRecords(), QgsAttributeEditor::createAttributeEditor(), QgsRuleBasedRendererV2::Rule::createFromSld(), QgsSymbolLayerV2Utils::createFunctionElement(), QgsAttributeAction::expandAction(), QgsSymbolLayerV2Utils::functionFromSldElement(), QgsAttributeTableModel::loadAttributes(), QgsSearchQueryBuilder::loadQuery(), QgsExpressionBuilderWidget::on_txtExpressionString_textChanged(), QgsDataDefined::prepareExpression(), QgsAttributeDialog::QgsAttributeDialog(), QgsPalLayerSettings::registerFeature(), replaceExpressionText(), QgsFeatureListModel::setDisplayExpression(), and QgsDataDefinedButton::updateGui().

QString QgsExpression::helptext ( QString name ) [static]

Definition at line 2359 of file qgsexpression.cpp.

References gFunctionHelpTexts, initFunctionHelp(), and tr.

Referenced by QgsExpression::Function::helptext(), and QgsExpressionBuilderWidget::loadFunctionHelp().

static void QgsExpression::initFunctionHelp ( ) [static, protected]

Referenced by helptext().

void QgsExpression::initGeomCalculator ( ) [protected]

Definition at line 1662 of file qgsexpression.cpp.

References mCalc, and QgsDistanceArea::setEllipsoidalMode().

Referenced by QgsExpression().

bool QgsExpression::isFunctionName ( QString name ) [static]

Definition at line 1589 of file qgsexpression.cpp.

References functionIndex().

bool QgsExpression::needsGeometry ( )

Returns true if the expression uses feature geometry for some computation.

Definition at line 1655 of file qgsexpression.cpp.

References mRootNode, and QgsExpression::Node::needsGeometry().

Referenced by QgsSearchQueryBuilder::countRecords(), QgsAttributeEditor::createAttributeEditor(), QgsAttributeTableModel::loadAttributes(), QgsExpressionBuilderWidget::on_txtExpressionString_textChanged(), and QgsAttributeDialog::QgsAttributeDialog().

QString QgsExpression::parserErrorString ( ) const [inline]

Returns parser error.

Definition at line 97 of file qgsexpression.h.

Referenced by QgsSearchQueryBuilder::countRecords(), QgsRuleBasedRendererV2::Rule::createFromSld(), QgsSymbolLayerV2Utils::createFunctionElement(), QgsAttributeAction::expandAction(), QgsSymbolLayerV2Utils::functionFromSldElement(), QgsSearchQueryBuilder::loadQuery(), QgsExpressionBuilderWidget::on_txtExpressionString_textChanged(), QgsDataDefined::prepareExpression(), QgsPalLayerSettings::registerFeature(), replaceExpressionText(), QgsFeatureListModel::setDisplayExpression(), and QgsDataDefinedButton::updateGui().

bool QgsExpression::prepare ( const QgsFields & fields )

Get the expression ready for evaluation - find out column indexes.

Definition at line 1676 of file qgsexpression.cpp.

References mEvalErrorString, mRootNode, QgsExpression::Node::prepare(), and tr.

Referenced by QgsSearchQueryBuilder::countRecords(), QgsAttributeEditor::createAttributeEditor(), evaluate(), QgsAttributeTableModel::loadAttributes(), QgsExpressionSelectionDialog::on_mActionAddToSelection_triggered(), QgsExpressionSelectionDialog::on_mActionRemoveFromSelection_triggered(), QgsExpressionSelectionDialog::on_mActionSelect_triggered(), QgsExpressionSelectionDialog::on_mActionSelectInstersect_triggered(), QgsDataDefined::prepareExpression(), QgsPalLabeling::prepareLayer(), and QgsFeatureListModel::setDisplayExpression().

static QString QgsExpression::quotedColumnRef ( QString name ) [inline, static]

return quoted column reference (in double quotes)

Definition at line 315 of file qgsexpression.h.

Referenced by QgsSearchQueryBuilder::on_lstFields_doubleClicked(), QgsRuleBasedRendererV2::refineRuleCategories(), and QgsRuleBasedRendererV2::refineRuleRanges().

static QString QgsExpression::quotedString ( QString text ) [inline, static]

return quoted string (in single quotes)

Definition at line 317 of file qgsexpression.h.

Referenced by QgsRuleBasedRendererV2::refineRuleCategories().

QStringList QgsExpression::referencedColumns ( )

Get list of columns referenced by the expression.

Definition at line 1632 of file qgsexpression.cpp.

References mRootNode, and QgsExpression::Node::referencedColumns().

Referenced by QgsAttributeEditor::createAttributeEditor(), QgsAttributeTableModel::loadAttributes(), QgsDataDefined::prepareExpression(), and QgsPalLabeling::prepareLayer().

bool QgsExpression::registerFunction ( QgsExpression::Function * function ) [static]

Definition at line 1367 of file qgsexpression.cpp.

References functionIndex(), and gmFunctions.

QString QgsExpression::replaceExpressionText	(	QString	action,
		QgsFeature *	feat,
		QgsVectorLayer *	layer,
		const QMap< QString, QVariant > *	substitutionMap = `0`
	)		`[static]`

This function currently replaces each expression between [% and %] in the string with the result of its evaluation on the feature passed as argument.

Additional substitutions can be passed through the substitutionMap parameter

Definition at line 1725 of file qgsexpression.cpp.

References evalErrorString(), evaluate(), hasEvalError(), hasParserError(), parserErrorString(), QgsVectorLayer::pendingFields(), QgsDebugMsg, setSpecialColumn(), and specialColumn().

Referenced by QgsComposerLabel::displayText(), QgsAttributeAction::doAction(), QgsMapTip::fetchFeature(), replaceExpressionText(), and QgsHtmlAnnotationItem::setFeatureForMapPosition().

QString QgsExpression::replaceExpressionText	(	QString	action,
		QgsFeature &	feat,
		QgsVectorLayer *	layer,
		const QMap< QString, QVariant > *	substitutionMap = `0`
	)		`[static]`

Definition at line 1800 of file qgsexpression.cpp.

References replaceExpressionText().

const Node* QgsExpression::rootNode ( ) const [inline]

Returns root node of the expression. Root node is null is parsing has failed.

Definition at line 102 of file qgsexpression.h.

Referenced by QgsOgcUtils::expressionToOgcFilter().

int QgsExpression::scale ( ) [inline]

Definition at line 151 of file qgsexpression.h.

Referenced by fcnScale().

void QgsExpression::setCurrentRowNumber ( int rowNumber ) [inline]

Set the number for $rownum special column.

Definition at line 138 of file qgsexpression.h.

void QgsExpression::setEvalErrorString ( QString str ) [inline]

Set evaluation error (used internally by evaluation functions)

Definition at line 135 of file qgsexpression.h.

Referenced by QgsExpression::NodeBinaryOperator::eval(), fcnColorCmyk(), fcnColorHsl(), fcnColorHsv(), fcnColorRgb(), fcnExpScale(), fcnLinearScale(), fcnRampColor(), fcnRegexpMatch(), fcnRegexpReplace(), fcnRegexpSubstr(), fncColorCmyka(), fncColorHsla(), fncColorHsva(), fncColorRgba(), getDateTimeValue(), getDateValue(), getDoubleValue(), getGeometry(), getInterval(), getIntValue(), getTimeValue(), getTVLValue(), and pointAt().

void QgsExpression::setGeomCalculator ( QgsDistanceArea & calc )

Sets the geometry calculator used in evaluation of expressions,.

Definition at line 1668 of file qgsexpression.cpp.

References QgsDistanceArea::ellipsoid(), QgsDistanceArea::ellipsoidalEnabled(), mCalc, QgsDistanceArea::setEllipsoid(), QgsDistanceArea::setEllipsoidalMode(), QgsDistanceArea::setSourceCrs(), and QgsDistanceArea::sourceCrs().

Referenced by QgsExpressionBuilderWidget::on_txtExpressionString_textChanged(), and QgsAttributeDialog::QgsAttributeDialog().

void QgsExpression::setScale ( double scale ) [inline]

Definition at line 149 of file qgsexpression.h.

Referenced by QgsDataDefined::prepareExpression(), and QgsPalLayerSettings::registerFeature().

void QgsExpression::setSpecialColumn	(	const QString &	name,
		QVariant	value
	)		`[static]`

Assign a special column.

Definition at line 1543 of file qgsexpression.cpp.

References functionIndex(), and gmSpecialColumns.

Referenced by QgsComposition::addPaperItem(), QgsAtlasComposition::beginRender(), QgsAtlasComposition::prepareForFeature(), QgsAtlasComposition::QgsAtlasComposition(), QgsComposition::removePaperItems(), replaceExpressionText(), QgsAtlasComposition::setCoverageLayer(), and QgsComposition::setNumPages().

QVariant QgsExpression::specialColumn ( const QString & name ) [static]

Return the value of the given special column or a null QVariant if undefined.

Definition at line 1563 of file qgsexpression.cpp.

References functionIndex(), and gmSpecialColumns.

Referenced by fcnSpecialColumn(), and replaceExpressionText().

QList< QgsExpression::Function * > QgsExpression::specialColumns ( ) [static]

Returns a list of special Column definitions.

Definition at line 1579 of file qgsexpression.cpp.

References gmSpecialColumns.

Referenced by QgsExpressionBuilderWidget::QgsExpressionBuilderWidget().

bool QgsExpression::unregisterFunction ( QString name ) [static]

Definition at line 1378 of file qgsexpression.cpp.

References BuiltinFunctions(), functionIndex(), and gmFunctions.

void QgsExpression::unsetSpecialColumn ( const QString & name ) [static]

Unset a special column.

Definition at line 1554 of file qgsexpression.cpp.

References gmSpecialColumns.

Friends And Related Function Documentation

friend class QgsOgcUtils [friend]

Definition at line 618 of file qgsexpression.h.

Member Data Documentation

const char * QgsExpression::BinaryOperatorText [static]

Initial value:

{
  "OR", "AND",
  "=", "<>", "<=", ">=", "<", ">", "~", "LIKE", "NOT LIKE", "ILIKE", "NOT ILIKE", "IS", "IS NOT",
  "+", "-", "*", "/", "%", "^",
  "||"
}