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. More...

QString	parserErrorString () const
	Returns parser error. More...

const Node *	rootNode () const
	Returns root node of the expression. Root node is null is parsing has failed. More...

bool	prepare (const QgsFields &fields)
	Get the expression ready for evaluation - find out column indexes. More...

QStringList	referencedColumns ()
	Get list of columns referenced by the expression. More...

bool	needsGeometry ()
	Returns true if the expression uses feature geometry for some computation. More...

QVariant	evaluate (const QgsFeature *f=NULL)
	Evaluate the feature and return the result. More...

QVariant	evaluate (const QgsFeature &f)
	Evaluate the feature and return the result. More...

QVariant	evaluate (const QgsFeature *f, const QgsFields &fields)
	Evaluate the feature and return the result. More...

QVariant	evaluate (const QgsFeature &f, const QgsFields &fields)
	Evaluate the feature and return the result. More...

bool	hasEvalError () const
	Returns true if an error occurred when evaluating last input. More...

QString	evalErrorString () const
	Returns evaluation error. More...

void	setEvalErrorString (QString str)
	Set evaluation error (used internally by evaluation functions) More...

void	setCurrentRowNumber (int rowNumber)
	Set the number for $rownum special column. More...

int	currentRowNumber ()
	Return the number used for $rownum special column. More...

void	setScale (double scale)

double	scale ()

const QString	expression () const
	Alias for dump() More...

QString	dump () const
	Return the expression string that represents this QgsExpression. More...

QgsDistanceArea *	geomCalculator ()
	Return calculator used for distance and area calculations (used by internal functions) More...

void	setGeomCalculator (const QgsDistanceArea &calc)
	Sets the geometry calculator used in evaluation of expressions,. More...

void	acceptVisitor (Visitor &v) const
	entry function for the visitor pattern More...

Static Public Member Functions
static void	setSpecialColumn (const QString &name, QVariant value)
	Assign a special column. More...

static void	unsetSpecialColumn (const QString &name)
	Unset a special column. More...

static QVariant	specialColumn (const QString &name)
	Return the value of the given special column or a null QVariant if undefined. More...

static bool	hasSpecialColumn (const QString &name)
	Check whether a special column exists. More...

static bool	isValid (const QString &text, const QgsFields &fields, QString &errorMessage)

static QString	replaceExpressionText (const QString &action, const 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. More...

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. More...

static QList< Function * >	specialColumns ()
	Returns a list of special Column definitions. More...

static QString	quotedColumnRef (QString name)
	return quoted column reference (in double quotes) More...

static QString	quotedString (QString text)
	return quoted string (in single quotes) More...

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
Node *	mRootNode

QString	mParserErrorString

QString	mEvalErrorString

int	mRowNumber

double	mScale

QString	mExp

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 89 of file qgsexpression.h.

Member Typedef Documentation

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

Definition at line 238 of file qgsexpression.h.

typedef QList<WhenThen*> QgsExpression::WhenThenList

Definition at line 562 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 190 of file qgsexpression.h.

enum QgsExpression::NodeType

Enumerator
ntUnaryOperator
ntBinaryOperator
ntInOperator
ntFunction
ntLiteral
ntColumnRef
ntCondition

Definition at line 327 of file qgsexpression.h.

enum QgsExpression::SpatialOperator

Enumerator
soBbox
soIntersects
soContains
soCrosses
soEquals
soDisjoint
soOverlaps
soTouches
soWithin

Definition at line 222 of file qgsexpression.h.

enum QgsExpression::UnaryOperator

Enumerator
uoNot
uoMinus

Definition at line 185 of file qgsexpression.h.

Constructor & Destructor Documentation

QgsExpression::QgsExpression ( const QString & expr )

Definition at line 1785 of file qgsexpression.cpp.

References mParserErrorString, mRootNode, and parseExpression().

QgsExpression::~QgsExpression ( )

Definition at line 1797 of file qgsexpression.cpp.

References mCalc, and mRootNode.

QgsExpression::QgsExpression ( )

inlineprotected

Definition at line 609 of file qgsexpression.h.

Member Function Documentation

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

entry function for the visitor pattern

Definition at line 1892 of file qgsexpression.cpp.

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

const QStringList & QgsExpression::BuiltinFunctions ( )

static

Definition at line 1519 of file qgsexpression.cpp.

References gmBuiltinFunctions.

Referenced by unregisterFunction().

int QgsExpression::currentRowNumber ( )

inline

Return the number used for $rownum special column.

Definition at line 143 of file qgsexpression.h.

Referenced by fcnRowNumber().

QString QgsExpression::dump ( ) const

Return the expression string that represents this QgsExpression.

Definition at line 1884 of file qgsexpression.cpp.

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

Referenced by QgsOgcUtils::expressionFromOgcFilter().

QString QgsExpression::evalErrorString ( ) const

inline

Returns evaluation error.

Definition at line 136 of file qgsexpression.h.

Referenced by QgsSearchQueryBuilder::countRecords(), QgsPalLayerSettings::dataDefinedValue(), QgsComposerPicture::evalPictureExpression(), QgsAttributeAction::expandAction(), QgsExpressionBuilderWidget::on_txtExpressionString_textChanged(), QgsDataDefined::prepareExpression(), QgsPalLabeling::prepareLayer(), QgsVectorLayer::readSldLabeling(), 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 1861 of file qgsexpression.cpp.

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

Referenced by QgsFeatureRequest::acceptFeature(), QgsSVGFillSymbolLayer::applyDataDefinedSettings(), QgsLinePatternFillSymbolLayer::applyDataDefinedSettings(), QgsPointPatternFillSymbolLayer::applyDataDefinedSettings(), QgsSimpleLineSymbolLayerV2::applyDataDefinedSymbology(), QgsSimpleFillSymbolLayerV2::applyDataDefinedSymbology(), QgsGradientFillSymbolLayerV2::applyDataDefinedSymbology(), QgsShapeburstFillSymbolLayerV2::applyDataDefinedSymbology(), QgsSearchQueryBuilder::countRecords(), QgsFeatureListModel::data(), QgsPalLayerSettings::dataDefinedValue(), QgsSimpleLineSymbolLayerV2::dxfColor(), QgsSimpleFillSymbolLayerV2::dxfColor(), QgsSimpleLineSymbolLayerV2::dxfWidth(), QgsSimpleFillSymbolLayerV2::dxfWidth(), QgsImageFillSymbolLayer::dxfWidth(), QgsComposerPicture::evalPictureExpression(), evaluate(), QgsAttributeAction::expandAction(), QgsVectorLayerFeatureIterator::fetchNextChangedAttributeFeature(), QgsComposerAttributeTable::getFeatureAttributes(), QgsMarkerSymbolLayerV2::markerOffset(), QgsAbstractFeatureIterator::nextFeatureFilterExpression(), QgsExpressionSelectionDialog::on_mActionAddToSelection_triggered(), QgsExpressionSelectionDialog::on_mActionRemoveFromSelection_triggered(), QgsExpressionSelectionDialog::on_mActionSelect_triggered(), QgsExpressionSelectionDialog::on_mActionSelectInstersect_triggered(), QgsExpressionBuilderWidget::on_txtExpressionString_textChanged(), QgsEllipseSymbolLayerV2::preparePath(), QgsPalLayerSettings::registerFeature(), QgsEllipseSymbolLayerV2::renderPoint(), QgsSimpleMarkerSymbolLayerV2::renderPoint(), QgsSvgMarkerSymbolLayerV2::renderPoint(), QgsMarkerLineSymbolLayerV2::renderPolyline(), QgsMarkerLineSymbolLayerV2::renderPolylineInterval(), QgsMarkerLineSymbolLayerV2::renderPolylineVertex(), replaceExpressionText(), QgsEllipseSymbolLayerV2::writeDxf(), QgsSimpleMarkerSymbolLayerV2::writeDxf(), and QgsSvgMarkerSymbolLayerV2::writeDxf().

QVariant QgsExpression::evaluate ( const QgsFeature & f )

inline

Evaluate the feature and return the result.

Note: prepare() should be called before calling this method; available in python bindings as evaluatePrepared

Definition at line 122 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 1873 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; not available in python bindings

Definition at line 131 of file qgsexpression.h.

References evaluate().

Referenced by evaluate().

const QString QgsExpression::expression ( ) const

inline

Alias for dump()

Definition at line 162 of file qgsexpression.h.

Referenced by QgsRuleBasedRendererV2::Rule::createFromSld(), QgsSymbolLayerV2::dataDefinedPropertyString(), QgsFeatureListModel::displayExpression(), QgsSymbolLayerV2Utils::fieldOrExpressionFromExpression(), QgsSymbolLayerV2Utils::functionFromSldElement(), QgsFeatureRequest::operator=(), and QgsEllipseSymbolLayerV2::writeSldMarker().

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 1779 of file qgsexpression.cpp.

References Functions().

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

int QgsExpression::functionIndex ( QString name )

static

Definition at line 1768 of file qgsexpression.cpp.

References functionCount(), and Functions().

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

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

static

Definition at line 1551 of file qgsexpression.cpp.

References fcnAbs(), fcnAcos(), fcnAge(), fcnAsin(), fcnAtan(), fcnAtan2(), fcnBbox(), fcnBounds(), fcnBoundsHeight(), fcnBoundsWidth(), 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(), fcnUuid(), fcnWeek(), fcnWithin(), fcnWordwrap(), fcnX(), fcnXat(), fcnXMax(), fcnXMin(), fcnY(), fcnYat(), fcnYear(), fcnYMax(), fcnYMin(), fncColorCmyka(), fncColorHsla(), fncColorHsva(), fncColorRgba(), and gmFunctions.

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

QgsDistanceArea* QgsExpression::geomCalculator ( )

inline

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

Definition at line 169 of file qgsexpression.h.

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

QString QgsExpression::group ( QString group )

static

Definition at line 2586 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 134 of file qgsexpression.h.

Referenced by QgsSearchQueryBuilder::countRecords(), QgsPalLayerSettings::dataDefinedValue(), QgsComposerPicture::evalPictureExpression(), QgsAttributeAction::expandAction(), QgsComposerPicture::loadPicture(), QgsExpressionBuilderWidget::on_txtExpressionString_textChanged(), QgsDataDefined::prepareExpression(), QgsPalLabeling::prepareLayer(), QgsVectorLayer::readSldLabeling(), QgsPalLayerSettings::registerFeature(), and replaceExpressionText().

bool QgsExpression::hasParserError ( ) const

inline

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

Definition at line 96 of file qgsexpression.h.

Referenced by QgsDataDefinedButton::aboutToShowMenu(), QgsSearchQueryBuilder::countRecords(), QgsRuleBasedRendererV2::Rule::createFromSld(), QgsSymbolLayerV2Utils::createFunctionElement(), QgsFieldModel::data(), QgsAttributeAction::expandAction(), QgsSymbolLayerV2Utils::fieldOrExpressionToExpression(), QgsSymbolLayerV2Utils::functionFromSldElement(), QgsFieldExpressionWidget::isExpressionValid(), isValid(), QgsSearchQueryBuilder::loadQuery(), QgsExpressionBuilderWidget::on_txtExpressionString_textChanged(), QgsDataDefined::prepareExpression(), QgsPalLayerSettings::registerFeature(), replaceExpressionText(), QgsFeatureListModel::setDisplayExpression(), QgsDataDefinedButton::updateGui(), QgsComposerPicture::updatePictureExpression(), QgsGraduatedSymbolRendererV2::usedAttributes(), and QgsCategorizedSymbolRendererV2::usedAttributes().

bool QgsExpression::hasSpecialColumn ( const QString & name )

static

Check whether a special column exists.

Note: added in 2.2

Definition at line 1709 of file qgsexpression.cpp.

References functionIndex(), gmSpecialColumns, and setSpecialColumn().

QString QgsExpression::helptext ( QString name )

static

Definition at line 2578 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 1833 of file qgsexpression.cpp.

References mCalc, and QgsDistanceArea::setEllipsoidalMode().

bool QgsExpression::isFunctionName ( QString name )

static

Definition at line 1763 of file qgsexpression.cpp.

References functionIndex().

bool QgsExpression::isValid	(	const QString &	text,
		const QgsFields &	fields,
		QString &	errorMessage
	)

static

Definition at line 1731 of file qgsexpression.cpp.

References hasParserError(), parserErrorString(), and prepare().

Referenced by isIntervalSafe(), and QgsFieldExpressionWidget::isValidExpression().

bool QgsExpression::needsGeometry ( )

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

Definition at line 1826 of file qgsexpression.cpp.

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

Referenced by QgsSearchQueryBuilder::countRecords().

QString QgsExpression::parserErrorString ( ) const

inline

Returns parser error.

Definition at line 98 of file qgsexpression.h.

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

bool QgsExpression::prepare ( const QgsFields & fields )

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

Definition at line 1849 of file qgsexpression.cpp.

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

Referenced by QgsSearchQueryBuilder::countRecords(), QgsFieldModel::data(), evaluate(), QgsComposerAttributeTable::getFeatureAttributes(), QgsFieldExpressionWidget::isExpressionValid(), isValid(), QgsExpressionSelectionDialog::on_mActionAddToSelection_triggered(), QgsExpressionSelectionDialog::on_mActionRemoveFromSelection_triggered(), QgsExpressionSelectionDialog::on_mActionSelect_triggered(), QgsExpressionSelectionDialog::on_mActionSelectInstersect_triggered(), QgsDataDefined::prepareExpression(), QgsPalLabeling::prepareLayer(), QgsVectorLayerFeatureIterator::QgsVectorLayerFeatureIterator(), QgsFeatureListModel::setDisplayExpression(), and QgsComposerPicture::updatePictureExpression().

QString QgsExpression::quotedColumnRef ( QString name )

static

return quoted column reference (in double quotes)

Definition at line 1749 of file qgsexpression.cpp.

Referenced by QgsExpression::NodeColumnRef::dump(), QgsSymbolLayerV2Utils::fieldOrExpressionToExpression(), QgsSearchQueryBuilder::on_lstFields_doubleClicked(), QgsRuleBasedRendererV2::refineRuleCategories(), and QgsRuleBasedRendererV2::refineRuleRanges().

QString QgsExpression::quotedString ( QString text )

static

return quoted string (in single quotes)

Definition at line 1754 of file qgsexpression.cpp.

Referenced by QgsExpression::NodeLiteral::dump(), and QgsRuleBasedRendererV2::refineRuleCategories().

QStringList QgsExpression::referencedColumns ( )

Get list of columns referenced by the expression.

Definition at line 1803 of file qgsexpression.cpp.

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

Referenced by QgsVectorLayerRenderer::prepareDiagrams(), QgsDataDefined::prepareExpression(), QgsPalLabeling::prepareLayer(), QgsGraduatedSymbolRendererV2::usedAttributes(), and QgsCategorizedSymbolRendererV2::usedAttributes().

bool QgsExpression::registerFunction ( QgsExpression::Function * function )

static

Definition at line 1488 of file qgsexpression.cpp.

References functionIndex(), and gmFunctions.

QString QgsExpression::replaceExpressionText	(	const QString &	action,
		const 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 1898 of file qgsexpression.cpp.

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

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

const Node* QgsExpression::rootNode ( ) const

inline

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

Definition at line 103 of file qgsexpression.h.

Referenced by QgsOgcUtils::expressionToOgcFilter(), and QgsSymbolLayerV2Utils::fieldOrExpressionFromExpression().

double QgsExpression::scale ( )

inline

Definition at line 159 of file qgsexpression.h.

Referenced by fcnScale().

void QgsExpression::setCurrentRowNumber ( int rowNumber )

inline

Set the number for $rownum special column.

Definition at line 141 of file qgsexpression.h.

Referenced by QgsComposerAttributeTable::getFeatureAttributes().

void QgsExpression::setEvalErrorString ( QString str )

inline

Set evaluation error (used internally by evaluation functions)

Definition at line 138 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 ( const QgsDistanceArea & calc )

Sets the geometry calculator used in evaluation of expressions,.

Definition at line 1843 of file qgsexpression.cpp.

References mCalc.

Referenced by QgsExpressionBuilderWidget::on_txtExpressionString_textChanged().

void QgsExpression::setScale ( double scale )

inline

Definition at line 157 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 1673 of file qgsexpression.cpp.

References functionIndex(), and gmSpecialColumns.

Referenced by QgsComposition::addPaperItem(), QgsAtlasComposition::beginRender(), QgsComposerMap::draw(), hasSpecialColumn(), QgsAtlasComposition::prepareForFeature(), QgsAtlasComposition::QgsAtlasComposition(), QgsMapCanvas::refreshMap(), QgsComposition::removePaperItems(), replaceExpressionText(), QgsAtlasComposition::setCoverageLayer(), QgsComposition::setNumPages(), and QgsAtlasComposition::updateFeatures().

QVariant QgsExpression::specialColumn ( const QString & name )

static

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

Definition at line 1693 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 1739 of file qgsexpression.cpp.

References gmSpecialColumns.

Referenced by QgsExpressionBuilderWidget::QgsExpressionBuilderWidget().

bool QgsExpression::unregisterFunction ( QString name )

static

Definition at line 1499 of file qgsexpression.cpp.

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

void QgsExpression::unsetSpecialColumn ( const QString & name )

static

Unset a special column.

Definition at line 1684 of file qgsexpression.cpp.

References gmSpecialColumns.

Friends And Related Function Documentation

friend class QgsOgcUtils

friend

Definition at line 625 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",
  "+", "-", "*", "/", "%", "^",
  "||"
}