QGIS API Documentation 3.29.0-Master (006c3c0232)
Public Member Functions | List of all members
QgsExpressionNodeIndexOperator Class Reference

A indexing expression operator, which allows use of square brackets [] to reference map and array items. More...

#include <qgsexpressionnodeimpl.h>

Inheritance diagram for QgsExpressionNodeIndexOperator:
Inheritance graph
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Public Member Functions

 QgsExpressionNodeIndexOperator (QgsExpressionNode *container, QgsExpressionNode *index)
 Constructor for QgsExpressionNodeIndexOperator. More...
 
 ~QgsExpressionNodeIndexOperator () override
 
QgsExpressionNodeclone () const override
 Generate a clone of this node. More...
 
QgsExpressionNodecontainer () const
 Returns the container node, representing an array or map value. 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...
 
QgsExpressionNodeindex () const
 Returns the index node, representing an array element index or map key. 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...
 
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...
 
- Public Member Functions inherited from QgsExpressionNode
virtual ~QgsExpressionNode ()=default
 
QVariant cachedStaticValue () const
 Returns the node's static cached value. More...
 
virtual QgsExpressionNodeclone () const =0
 Generate a clone of this node. More...
 
virtual QString dump () const =0
 Dump this node into a serialized (part) of an expression. More...
 
const QgsExpressionNodeeffectiveNode () const
 Returns a reference to the simplest node which represents this node, after any compilation optimizations have been applied. 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...
 
virtual bool isStatic (QgsExpression *parent, const QgsExpressionContext *context) const =0
 Returns true if this node can be evaluated for a static value. More...
 
virtual bool needsGeometry () const =0
 Abstract virtual method which returns if the geometry is required to evaluate this expression. More...
 
virtual QList< const QgsExpressionNode * > nodes () const =0
 Returns a list of all nodes which are used in this expression. More...
 
virtual QgsExpressionNode::NodeType nodeType () const =0
 Gets the type of this node. More...
 
bool prepare (QgsExpression *parent, const QgsExpressionContext *context)
 Prepare this node for evaluation. More...
 
virtual QSet< QString > referencedColumns () const =0
 Abstract virtual method which returns a list of columns required to evaluate this node. More...
 
virtual QSet< QString > referencedFunctions () const =0
 Returns a set of all functions which are used in this expression. More...
 
virtual QSet< QString > referencedVariables () const =0
 Returns a set of all variables which are used in this expression. More...
 

Additional Inherited Members

- Public Types inherited from QgsExpressionNode
enum  NodeType {
  ntUnaryOperator , ntBinaryOperator , ntInOperator , ntFunction ,
  ntLiteral , ntColumnRef , ntCondition , ntIndexOperator ,
  ntBetweenOperator
}
 Known node types. More...
 
- 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
 QgsExpressionNode ()=default
 Constructor. More...
 
 QgsExpressionNode (const QgsExpressionNode &other)
 Copy constructor. More...
 
void cloneTo (QgsExpressionNode *target) const
 Copies the members of this node to the node provided in target. More...
 
QgsExpressionNodeoperator= (const QgsExpressionNode &other)
 Assignment operator. More...
 
- Protected Attributes inherited from QgsExpressionNode
QVariant mCachedStaticValue
 Contains the static, precalculated value for the node if mHasCachedValue is true. More...
 
std::unique_ptr< QgsExpressionNodemCompiledSimplifiedNode
 Contains a compiled node which represents a simplified version of this node as a result of compilation optimizations. More...
 
bool mHasCachedValue = false
 true if the node has a static, precalculated value. More...
 

Detailed Description

A indexing expression operator, which allows use of square brackets [] to reference map and array items.

Since
QGIS 3.6

Definition at line 230 of file qgsexpressionnodeimpl.h.

Constructor & Destructor Documentation

◆ QgsExpressionNodeIndexOperator()

QgsExpressionNodeIndexOperator::QgsExpressionNodeIndexOperator ( QgsExpressionNode container,
QgsExpressionNode index 
)
inline

Constructor for QgsExpressionNodeIndexOperator.

Definition at line 237 of file qgsexpressionnodeimpl.h.

◆ ~QgsExpressionNodeIndexOperator()

QgsExpressionNodeIndexOperator::~QgsExpressionNodeIndexOperator ( )
inlineoverride

Definition at line 241 of file qgsexpressionnodeimpl.h.

Member Function Documentation

◆ clone()

QgsExpressionNode * QgsExpressionNodeIndexOperator::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 2068 of file qgsexpressionnodeimpl.cpp.

◆ container()

QgsExpressionNode * QgsExpressionNodeIndexOperator::container ( ) const
inline

Returns the container node, representing an array or map value.

See also
index()

Definition at line 247 of file qgsexpressionnodeimpl.h.

◆ dump()

QString QgsExpressionNodeIndexOperator::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 2032 of file qgsexpressionnodeimpl.cpp.

◆ evalNode()

QVariant QgsExpressionNodeIndexOperator::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 1983 of file qgsexpressionnodeimpl.cpp.

◆ index()

QgsExpressionNode * QgsExpressionNodeIndexOperator::index ( ) const
inline

Returns the index node, representing an array element index or map key.

See also
container()

Definition at line 253 of file qgsexpressionnodeimpl.h.

◆ isStatic()

bool QgsExpressionNodeIndexOperator::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 2075 of file qgsexpressionnodeimpl.cpp.

◆ needsGeometry()

bool QgsExpressionNodeIndexOperator::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 2063 of file qgsexpressionnodeimpl.cpp.

◆ nodes()

QList< const QgsExpressionNode * > QgsExpressionNodeIndexOperator::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 2055 of file qgsexpressionnodeimpl.cpp.

◆ nodeType()

QgsExpressionNode::NodeType QgsExpressionNodeIndexOperator::nodeType ( ) const
overridevirtual

Gets the type of this node.

Returns
The type of this node

Implements QgsExpressionNode.

Definition at line 2020 of file qgsexpressionnodeimpl.cpp.

◆ prepareNode()

bool QgsExpressionNodeIndexOperator::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 2025 of file qgsexpressionnodeimpl.cpp.

◆ referencedColumns()

QSet< QString > QgsExpressionNodeIndexOperator::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 2037 of file qgsexpressionnodeimpl.cpp.

◆ referencedFunctions()

QSet< QString > QgsExpressionNodeIndexOperator::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 2050 of file qgsexpressionnodeimpl.cpp.

◆ referencedVariables()

QSet< QString > QgsExpressionNodeIndexOperator::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 2045 of file qgsexpressionnodeimpl.cpp.


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