QGIS API Documentation
2.14.0-Essen
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Expression function for use within a QgsExpressionContextScope. More...
#include <qgsexpressioncontext.h>
Public Member Functions | |
QgsScopedExpressionFunction (const QString &fnname, int params, const QString &group, const QString &helpText=QString(), bool usesGeometry=false, const QStringList &referencedColumns=QStringList(), bool lazyEval=false, bool handlesNull=false, bool isContextual=true) | |
virtual | ~QgsScopedExpressionFunction () |
virtual QgsScopedExpressionFunction * | clone () const =0 |
Returns a clone of the function. More... | |
virtual QVariant | func (const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent) override=0 |
Returns result of evaluating the function. More... | |
Public Member Functions inherited from QgsExpression::Function | |
Function (const QString &fnname, int params, const QString &group, const QString &helpText=QString(), bool usesGeometry=false, const QStringList &referencedColumns=QStringList(), bool lazyEval=false, bool handlesNull=false, bool isContextual=false) | |
virtual | ~Function () |
virtual QStringList | aliases () const |
Returns a list of possible aliases for the function. More... | |
virtual Q_DECL_DEPRECATED QVariant | func (const QVariantList &, const QgsFeature *, QgsExpression *) |
QString | group () |
The group the function belongs to. More... | |
virtual bool | handlesNull () const |
const QString | helptext () |
The help text for the function. More... | |
bool | isContextual () const |
Returns whether the function is only available if provided by a QgsExpressionContext object. More... | |
bool | lazyEval () |
True if this function should use lazy evaluation. More... | |
QString | name () |
The name of the function. More... | |
bool | operator== (const Function &other) const |
int | params () |
The number of parameters this function takes. More... | |
virtual QStringList | referencedColumns () const |
bool | usesgeometry () |
Does this function use a geometry object. More... | |
Expression function for use within a QgsExpressionContextScope.
This differs from a standard QgsExpression::Function in that it requires an implemented clone() method.
Definition at line 41 of file qgsexpressioncontext.h.
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inline |
Definition at line 44 of file qgsexpressioncontext.h.
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inlinevirtual |
Definition at line 56 of file qgsexpressioncontext.h.
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pure virtual |
Returns a clone of the function.
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overridepure virtual |
Returns result of evaluating the function.
values | list of values passed to the function |
context | context expression is being evaluated against |
parent | parent expression |
Reimplemented from QgsExpression::Function.