QGIS API Documentation  3.9.0-Master (224899f119)
Public Member Functions | Static Public Member Functions | List of all members
QgsExpressionNodeFunction Class Reference

An expression node for expression functions. More...

#include <qgsexpressionnodeimpl.h>

Inheritance diagram for QgsExpressionNodeFunction:
Inheritance graph
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Public Member Functions

 QgsExpressionNodeFunction (int fnIndex, QgsExpressionNode::NodeList *args)
 A function node consists of an index of the function in the global function array and a list of arguments that will be passed to it. More...
 
 ~QgsExpressionNodeFunction () override
 
QgsExpressionNode::NodeListargs () const
 Returns a list of arguments specified for the function. More...
 
QgsExpressionNodeclone () 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...
 
int fnIndex () const
 Returns the index of the node's function. 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 eval (QgsExpression *parent, const QgsExpressionContext *context)
 Evaluate this node with the given context and parent. More...
 
bool prepare (QgsExpression *parent, const QgsExpressionContext *context)
 Prepare this node for evaluation. More...
 

Static Public Member Functions

static bool validateParams (int fnIndex, QgsExpressionNode::NodeList *args, QString &error)
 Tests whether the provided argument list is valid for the matching function. More...
 

Additional Inherited Members

- Public Types inherited from QgsExpressionNode
enum  NodeType {
  ntUnaryOperator, ntBinaryOperator, ntInOperator, ntFunction,
  ntLiteral, ntColumnRef, ntCondition, ntIndexOperator
}
 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
void cloneTo (QgsExpressionNode *target) const
 Copies the members of this node to the node provided in target. More...
 

Detailed Description

An expression node for expression functions.

Definition at line 316 of file qgsexpressionnodeimpl.h.

Constructor & Destructor Documentation

◆ QgsExpressionNodeFunction()

QgsExpressionNodeFunction::QgsExpressionNodeFunction ( int  fnIndex,
QgsExpressionNode::NodeList args 
)

A function node consists of an index of the function in the global function array and a list of arguments that will be passed to it.

Definition at line 891 of file qgsexpressionnodeimpl.cpp.

◆ ~QgsExpressionNodeFunction()

QgsExpressionNodeFunction::~QgsExpressionNodeFunction ( )
override

Definition at line 931 of file qgsexpressionnodeimpl.cpp.

Member Function Documentation

◆ args()

QgsExpressionNode::NodeList* QgsExpressionNodeFunction::args ( ) const
inline

Returns a list of arguments specified for the function.

Definition at line 336 of file qgsexpressionnodeimpl.h.

◆ clone()

QgsExpressionNode * QgsExpressionNodeFunction::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 1063 of file qgsexpressionnodeimpl.cpp.

◆ dump()

QString QgsExpressionNodeFunction::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 957 of file qgsexpressionnodeimpl.cpp.

◆ evalNode()

QVariant QgsExpressionNodeFunction::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 879 of file qgsexpressionnodeimpl.cpp.

◆ fnIndex()

int QgsExpressionNodeFunction::fnIndex ( ) const
inline

Returns the index of the node's function.

Definition at line 331 of file qgsexpressionnodeimpl.h.

◆ isStatic()

bool QgsExpressionNodeFunction::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 1070 of file qgsexpressionnodeimpl.cpp.

◆ needsGeometry()

bool QgsExpressionNodeFunction::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 1051 of file qgsexpressionnodeimpl.cpp.

◆ nodes()

QList< const QgsExpressionNode * > QgsExpressionNodeFunction::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 1036 of file qgsexpressionnodeimpl.cpp.

◆ nodeType()

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

Gets the type of this node.

Returns
The type of this node

Implements QgsExpressionNode.

Definition at line 936 of file qgsexpressionnodeimpl.cpp.

◆ prepareNode()

bool QgsExpressionNodeFunction::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 941 of file qgsexpressionnodeimpl.cpp.

◆ referencedColumns()

QSet< QString > QgsExpressionNodeFunction::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.

Returns
A list of columns required to evaluate this expression

Implements QgsExpressionNode.

Definition at line 966 of file qgsexpressionnodeimpl.cpp.

◆ referencedFunctions()

QSet< QString > QgsExpressionNodeFunction::referencedFunctions ( ) const
overridevirtual

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

Implements QgsExpressionNode.

Definition at line 1019 of file qgsexpressionnodeimpl.cpp.

◆ referencedVariables()

QSet< QString > QgsExpressionNodeFunction::referencedVariables ( ) const
overridevirtual

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

Implements QgsExpressionNode.

Definition at line 989 of file qgsexpressionnodeimpl.cpp.

◆ validateParams()

bool QgsExpressionNodeFunction::validateParams ( int  fnIndex,
QgsExpressionNode::NodeList args,
QString &  error 
)
static

Tests whether the provided argument list is valid for the matching function.

Definition at line 1075 of file qgsexpressionnodeimpl.cpp.


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