A unary node is either negative as in boolean (not) or as in numbers (minus). More...

#include <qgsexpressionnodeimpl.h>

Inheritance diagram for QgsExpressionNodeUnaryOperator:

Public Types
enum	UnaryOperator { uoNot , uoMinus }
	list of unary operators More...

Public Types inherited from QgsExpressionNode
enum	NodeType { ntUnaryOperator , ntBinaryOperator , ntInOperator , ntFunction , ntLiteral , ntColumnRef , ntCondition , ntIndexOperator }
	Known node types. More...

Public Member Functions
	QgsExpressionNodeUnaryOperator (QgsExpressionNodeUnaryOperator::UnaryOperator op, QgsExpressionNode *operand)
	A node unary operator is modifying the value of operand by negating it with op. More...

	~QgsExpressionNodeUnaryOperator () override

QgsExpressionNode *	clone () const override
	Generate a clone of this node. More...

QString	dump () const override
	Dump this node into a serialized (part) of an expression. More...

QVariant	evalNode (QgsExpression parent, const QgsExpressionContext context) override
	Abstract virtual eval method Errors are reported to the parent. More...

bool	isStatic (QgsExpression parent, const QgsExpressionContext context) const override
	Returns `true` if this node can be evaluated for a static value. More...

bool	needsGeometry () const override
	Abstract virtual method which returns if the geometry is required to evaluate this expression. More...

QList< const QgsExpressionNode * >	nodes () const override
	Returns a list of all nodes which are used in this expression. More...

QgsExpressionNode::NodeType	nodeType () const override
	Gets the type of this node. More...

QgsExpressionNodeUnaryOperator::UnaryOperator	op () const
	Returns the unary operator. More...

QgsExpressionNode *	operand () const
	Returns the node the operator will operate upon. More...

bool	prepareNode (QgsExpression parent, const QgsExpressionContext context) override
	Abstract virtual preparation method Errors are reported to the parent. More...

QSet< QString >	referencedColumns () const override
	Abstract virtual method which returns a list of columns required to evaluate this node. More...

QSet< QString >	referencedFunctions () const override
	Returns a set of all functions which are used in this expression. More...

QSet< QString >	referencedVariables () const override
	Returns a set of all variables which are used in this expression. More...

QString	text () const
	Returns a the name of this operator without the operands. More...

Public Member Functions inherited from QgsExpressionNode
virtual	~QgsExpressionNode ()=default

QVariant	cachedStaticValue () const
	Returns the node's static cached value. More...

QVariant	eval (QgsExpression parent, const QgsExpressionContext context)
	Evaluate this node with the given context and parent. More...

bool	hasCachedStaticValue () const
	Returns `true` if the node can be replaced by a static cached value. More...

bool	prepare (QgsExpression parent, const QgsExpressionContext context)
	Prepare this node for evaluation. More...

Additional Inherited Members
Public Attributes inherited from QgsExpressionNode
int	parserFirstColumn = 0
	First column in the parser this node was found. More...

int	parserFirstLine = 0
	First line in the parser this node was found. More...

int	parserLastColumn = 0
	Last column in the parser this node was found. More...

int	parserLastLine = 0
	Last line in the parser this node was found. More...

Protected Member Functions inherited from QgsExpressionNode
void	cloneTo (QgsExpressionNode *target) const
	Copies the members of this node to the node provided in target. More...

Detailed Description

A unary node is either negative as in boolean (not) or as in numbers (minus).

Definition at line 27 of file qgsexpressionnodeimpl.h.

Member Enumeration Documentation

◆ UnaryOperator

enum QgsExpressionNodeUnaryOperator::UnaryOperator

list of unary operators

Note: if any change is made here, the definition of QgsExpression::UnaryOperatorText[] must be adapted.

Enumerator
uoNot
uoMinus

Definition at line 35 of file qgsexpressionnodeimpl.h.

Constructor & Destructor Documentation

◆ QgsExpressionNodeUnaryOperator()

QgsExpressionNodeUnaryOperator::QgsExpressionNodeUnaryOperator	(	QgsExpressionNodeUnaryOperator::UnaryOperator	op,
		QgsExpressionNode *	operand
	)

inline

A node unary operator is modifying the value of operand by negating it with op.

Definition at line 44 of file qgsexpressionnodeimpl.h.

◆ ~QgsExpressionNodeUnaryOperator()

QgsExpressionNodeUnaryOperator::~QgsExpressionNodeUnaryOperator ( )

inlineoverride

Definition at line 48 of file qgsexpressionnodeimpl.h.

Member Function Documentation

◆ clone()

QgsExpressionNode * QgsExpressionNodeUnaryOperator::clone ( ) const

overridevirtual

Generate a clone of this node.

Ownership is transferred to the caller.

Returns: a deep copy of this node.

Implements QgsExpressionNode.

Definition at line 181 of file qgsexpressionnodeimpl.cpp.

◆ dump()

QString QgsExpressionNodeUnaryOperator::dump ( ) const

overridevirtual

Dump this node into a serialized (part) of an expression.

The returned expression does not necessarily literally match the original expression, it's just guaranteed to behave the same way.

Implements QgsExpressionNode.

Definition at line 142 of file qgsexpressionnodeimpl.cpp.

◆ evalNode()

QVariant QgsExpressionNodeUnaryOperator::evalNode	(	QgsExpression *	parent,
		const QgsExpressionContext *	context
	)

overridevirtual

Abstract virtual eval method Errors are reported to the parent.

Since: QGIS 3.0

Implements QgsExpressionNode.

Definition at line 107 of file qgsexpressionnodeimpl.cpp.

◆ isStatic()

bool QgsExpressionNodeUnaryOperator::isStatic	(	QgsExpression *	parent,
		const QgsExpressionContext *	context
	)		const

overridevirtual

Returns true if this node can be evaluated for a static value.

This is used during the prepare() step and in case it returns true, the value of this node will already be evaluated and the result cached (and therefore not re-evaluated in subsequent calls to eval()). In case this returns true, prepareNode() will never be called.

Since: QGIS 3.0

Implements QgsExpressionNode.

Definition at line 188 of file qgsexpressionnodeimpl.cpp.

◆ needsGeometry()

bool QgsExpressionNodeUnaryOperator::needsGeometry ( ) const

overridevirtual

Abstract virtual method which returns if the geometry is required to evaluate this expression.

This needs to call needsGeometry() recursively on any child nodes.

Returns: true if a geometry is required to evaluate this expression

Implements QgsExpressionNode.

Definition at line 176 of file qgsexpressionnodeimpl.cpp.

◆ nodes()

QList< const QgsExpressionNode * > QgsExpressionNodeUnaryOperator::nodes ( ) const

overridevirtual

Returns a list of all nodes which are used in this expression.

Note: not available in Python bindings

Since: QGIS 3.2

Implements QgsExpressionNode.

Definition at line 168 of file qgsexpressionnodeimpl.cpp.

◆ nodeType()

QgsExpressionNode::NodeType QgsExpressionNodeUnaryOperator::nodeType ( ) const

overridevirtual

Gets the type of this node.

Returns: The type of this node

Implements QgsExpressionNode.

Definition at line 132 of file qgsexpressionnodeimpl.cpp.

◆ op()

QgsExpressionNodeUnaryOperator::UnaryOperator QgsExpressionNodeUnaryOperator::op ( ) const

inline

Returns the unary operator.

Definition at line 53 of file qgsexpressionnodeimpl.h.

◆ operand()

QgsExpressionNode* QgsExpressionNodeUnaryOperator::operand ( ) const

inline

Returns the node the operator will operate upon.

Definition at line 58 of file qgsexpressionnodeimpl.h.

◆ prepareNode()

bool QgsExpressionNodeUnaryOperator::prepareNode	(	QgsExpression *	parent,
		const QgsExpressionContext *	context
	)

overridevirtual

Abstract virtual preparation method Errors are reported to the parent.

Since: QGIS 3.0

Implements QgsExpressionNode.

Definition at line 137 of file qgsexpressionnodeimpl.cpp.

◆ referencedColumns()

QSet< QString > QgsExpressionNodeUnaryOperator::referencedColumns ( ) const

overridevirtual

Abstract virtual method which returns a list of columns required to evaluate this node.

When reimplementing this, you need to return any column that is required to evaluate this node and in addition recursively collect all the columns required to evaluate child nodes.

Warning: If the expression has been prepared via a call to QgsExpression::prepare(), or a call to QgsExpressionNode::prepare() for a node has been made, then some nodes in the expression may have been determined to evaluate to a static pre-calculatable value. In this case the results will omit attribute indices which are used by these pre-calculated nodes, regardless of their actual referenced columns. If you are seeking to use these functions to introspect an expression you must take care to do this with an unprepared expression node.

Returns: A list of columns required to evaluate this expression

Implements QgsExpressionNode.

Definition at line 150 of file qgsexpressionnodeimpl.cpp.

◆ referencedFunctions()

QSet< QString > QgsExpressionNodeUnaryOperator::referencedFunctions ( ) const

overridevirtual

Returns a set of all functions which are used in this expression.

Note: In contrast to the referencedColumns() function this method is not affected by any previous calls to QgsExpressionNode::prepare().

Implements QgsExpressionNode.

Definition at line 163 of file qgsexpressionnodeimpl.cpp.

◆ referencedVariables()

QSet< QString > QgsExpressionNodeUnaryOperator::referencedVariables ( ) const

overridevirtual

Returns a set of all variables which are used in this expression.

Note: In contrast to the referencedColumns() function this method is not affected by any previous calls to QgsExpressionNode::prepare().

Implements QgsExpressionNode.

Definition at line 158 of file qgsexpressionnodeimpl.cpp.

◆ text()

QString QgsExpressionNodeUnaryOperator::text ( ) const

Returns a the name of this operator without the operands.

I.e. "NOT" or "-"

Definition at line 193 of file qgsexpressionnodeimpl.cpp.

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

/build/qgis-3.18.1+99unstable/src/core/expression/qgsexpressionnodeimpl.h
/build/qgis-3.18.1+99unstable/src/core/expression/qgsexpressionnodeimpl.cpp

Public Types

Public Member Functions

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ UnaryOperator

Constructor & Destructor Documentation

◆ QgsExpressionNodeUnaryOperator()

◆ ~QgsExpressionNodeUnaryOperator()

Member Function Documentation

◆ clone()

◆ dump()

◆ evalNode()

◆ isStatic()

◆ needsGeometry()

◆ nodes()

◆ nodeType()

◆ op()

◆ operand()

◆ prepareNode()

◆ referencedColumns()

◆ referencedFunctions()

◆ referencedVariables()

◆ text()