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	UnaryOperator { uoNot, uoMinus }
enum	BinaryOperator { boOr, boAnd, boEQ, boNE, boLE, boGE, boLT, boGT, boRegexp, boLike, boNotLike, boILike, boNotILike, boIs, boIsNot, boPlus, boMinus, boMul, boDiv, boMod, boPow, boConcat }
enum	SpatialOperator { soBbox, soIntersects, soContains, soCrosses, soEquals, soDisjoint, soOverlaps, soTouches, soWithin }
enum	NodeType { ntUnaryOperator, ntBinaryOperator, ntInOperator, ntFunction, ntLiteral, ntColumnRef, ntCondition }
typedef QVariant(*	FcnEval )(const QVariantList &values, const QgsFeature f, QgsExpression parent)
typedef QList< WhenThen * >	WhenThenList

Public Member Functions
	QgsExpression (const QString &expr)
	~QgsExpression ()
bool	hasParserError () const
	Returns true if an error occurred when parsing the input expression.
QString	parserErrorString () const
	Returns parser error.
const Node *	rootNode () const
	Returns root node of the expression. Root node is null is parsing has failed.
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.
bool	needsGeometry ()
	Returns true if the expression uses feature geometry for some computation.
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.
bool	hasEvalError () const
	Returns true if an error occurred when evaluating last input.
QString	evalErrorString () const
	Returns evaluation error.
void	setEvalErrorString (QString str)
	Set evaluation error (used internally by evaluation functions)
void	setCurrentRowNumber (int rowNumber)
	Set the number for $rownum special column.
int	currentRowNumber ()
	Return the number used for $rownum special column.
void	setScale (double scale)
int	scale ()
const QString &	expression () const
QString	dump () const
	Return the parsed expression as a string - useful for debugging.
QgsDistanceArea *	geomCalculator ()
	Return calculator used for distance and area calculations (used by internal functions)
void	setGeomCalculator (QgsDistanceArea &calc)
	Sets the geometry calculator used in evaluation of expressions,.
void	acceptVisitor (Visitor &v) const
	entry function for the visitor pattern

Static Public Member Functions
static void	setSpecialColumn (const QString &name, QVariant value)
	Assign a special column.
static void	unsetSpecialColumn (const QString &name)
	Unset a special column.
static QVariant	specialColumn (const QString &name)
	Return the value of the given special column or a null QVariant if undefined.
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 const QList< Function * > &	Functions ()
static const QStringList &	BuiltinFunctions ()
static bool	registerFunction (Function *function)
static bool	unregisterFunction (QString name)
static bool	isFunctionName (QString name)
static int	functionIndex (QString name)
static int	functionCount ()
	Returns the number of functions defined in the parser.
static QList< Function * >	specialColumns ()
	Returns a list of special Column definitions.
static QString	quotedColumnRef (QString name)
	return quoted column reference (in double quotes)
static QString	quotedString (QString text)
	return quoted string (in single quotes)
static QString	helptext (QString name)
static QString	group (QString group)

Static Public Attributes
static const char *	BinaryOperatorText []
static const char *	UnaryOperatorText []
static QList< Function * >	gmFunctions
static QStringList	gmBuiltinFunctions

Protected Member Functions
	QgsExpression ()
void	initGeomCalculator ()

Static Protected Member Functions
static void	initFunctionHelp ()

Protected Attributes
QString	mExpression
Node *	mRootNode
QString	mParserErrorString
QString	mEvalErrorString
int	mRowNumber
double	mScale
QgsDistanceArea *	mCalc

Static Protected Attributes
static QMap< QString, QVariant >	gmSpecialColumns
static QHash< QString, QString >	gFunctionHelpTexts
static QHash< QString, QString >	gGroups

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 mExpression, mParserErrorString, mRootNode, and parseExpression().

QgsExpression::~QgsExpression ( )

Definition at line 1623 of file qgsexpression.cpp.

References mCalc, and mRootNode.

QgsExpression::QgsExpression ( )

inlineprotected

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 1723 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 1715 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 1692 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 1704 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 2371 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 2363 of file qgsexpression.cpp.

References gFunctionHelpTexts, initFunctionHelp(), and tr.

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

void QgsExpression::initFunctionHelp ( )

staticprotected

Definition at line 6 of file qgsexpression_texts.cpp.

References gFunctionHelpTexts.

Referenced by helptext().

void QgsExpression::initGeomCalculator ( )

protected

Definition at line 1659 of file qgsexpression.cpp.

References mCalc, and QgsDistanceArea::setEllipsoidalMode().

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 1652 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 1680 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 )

inlinestatic

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 )

inlinestatic

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 1629 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 1729 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 1804 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 1669 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",
  "+", "-", "*", "/", "%", "^",
  "||"
}