QgsExpressionNodeInOperator class

An expression node for value IN or NOT IN clauses.

Reference

Base classes

class QgsExpressionNode: Abstract base class for all nodes that can appear in an expression.

Constructors, destructors, conversion operators

QgsExpressionNodeInOperator(QgsExpressionNode* node, QgsExpressionNode::NodeList* list, bool notin = false): This node tests if the result of node is in the result of list.

Public functions

auto clone() const -> QgsExpressionNode* override: Generate a clone of this node.
auto dump() const -> QString override: Dump this node into a serialized (part) of an expression.
auto evalNode(QgsExpression* parent, const QgsExpressionContext* context) -> QVariant override: Abstract virtual eval method Errors are reported to the parent.
auto isNotIn() const -> bool: Returns true if this node is a "NOT IN" operator, or false if the node is a normal "IN" operator.
auto isStatic(QgsExpression* parent, const QgsExpressionContext* context) const -> bool override: Returns true if this node can be evaluated for a static value.
auto list() const -> QgsExpressionNode::NodeList*: Returns the list of nodes to search for matching values within.
auto needsGeometry() const -> bool override: Abstract virtual method which returns if the geometry is required to evaluate this expression.
auto node() const -> QgsExpressionNode*: Returns the expression node.
auto nodes() const -> QList<const QgsExpressionNode*> override: Returns a list of all nodes which are used in this expression.
auto nodeType() const -> QgsExpressionNode::NodeType override: Gets the type of this node.
auto prepareNode(QgsExpression* parent, const QgsExpressionContext* context) -> bool override: Abstract virtual preparation method Errors are reported to the parent.
auto referencedColumns() const -> QSet<QString> override: Abstract virtual method which returns a list of columns required to evaluate this node.
auto referencedFunctions() const -> QSet<QString> override: Returns a set of all functions which are used in this expression.
auto referencedVariables() const -> QSet<QString> override: Returns a set of all variables which are used in this expression.

Function documentation

QgsExpressionNodeInOperator::QgsExpressionNodeInOperator(QgsExpressionNode* node, QgsExpressionNode::NodeList* list, bool notin = false)

This node tests if the result of node is in the result of list.

Optionally it can be inverted with notin which by default is false.

QgsExpressionNode* QgsExpressionNodeInOperator::clone() const override

Generate a clone of this node.

Returns	a deep copy of this node.

Ownership is transferred to the caller.

QString QgsExpressionNodeInOperator::dump() const override

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.

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

Abstract virtual eval method Errors are reported to the parent.

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

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.

bool QgsExpressionNodeInOperator::needsGeometry() const override

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

Returns	true if a geometry is required to evaluate this expression

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

QList<const QgsExpressionNode*> QgsExpressionNodeInOperator::nodes() const override

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

QgsExpressionNode::NodeType QgsExpressionNodeInOperator::nodeType() const override

Gets the type of this node.

Returns	The type of this node

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

Abstract virtual preparation method Errors are reported to the parent.

QSet<QString> QgsExpressionNodeInOperator::referencedColumns() const override

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

Returns	A list of columns required to evaluate this expression

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.