bool QgsDataDefined::prepareExpression( QgsVectorLayer* layer )
{
if ( layer )
{
return prepareExpression( layer->fields() );
}
else
{
//preparing expression without a layer set, so pass empty field list
QgsFields empty;
return prepareExpression( empty );
}
}
bool QgsDataDefined::prepareExpression( QgsVectorLayer* layer )
{
if ( layer )
{
return prepareExpression( QgsExpressionContextUtils::createFeatureBasedContext( QgsFeature(), layer->fields() ) );
}
else
{
//preparing expression without a layer set, so pass empty context
QgsExpressionContext empty;
return prepareExpression( empty );
}
}
std::string EXParser::evaluate(std::string _expression)
{
steps.clear(); //clear previous solve steps
findAndReplaceVariables(_expression, this->variables);
try{
prepareExpression(_expression);
priorityLoop(_expression); //main calculation loop
}
catch(EXError &error){
steps.push_back(EXSolveStep(error.first, "stopped_evaluation"));
return error.first;
}
return _expression;
}
std::string EXParser::evaluate(std::string _expression)
{
steps.clear(); //clear previous solve steps
findAndReplaceVariables(_expression, this->variables);
prepareExpression(_expression);
if(!priorityLoop(_expression)) //main calculation loop
return mErrorStr;
return _expression;
}
QStringList QgsDataDefined::referencedColumns( QgsVectorLayer* layer )
{
if ( !mExprRefColmuns.isEmpty() )
{
return mExprRefColmuns;
}
if ( mUseExpression )
{
if ( !mExpression || !mExpressionPrepared )
{
prepareExpression( layer );
}
}
else if ( !mField.isEmpty() )
{
mExprRefColmuns << mField;
}
return mExprRefColmuns;
}
QStringList QgsDataDefined::referencedColumns( const QgsFields &fields )
{
if ( !d->exprRefColumns.isEmpty() )
{
return d->exprRefColumns;
}
d.detach();
if ( d->useExpression )
{
if ( !d->expression || !d->expressionPrepared )
{
prepareExpression( fields );
}
}
else if ( !d->field.isEmpty() )
{
d->exprRefColumns << d->field;
}
return d->exprRefColumns;
}
bool QgsDataDefined::prepareExpression( const QgsFields &fields )
{
return prepareExpression( QgsExpressionContextUtils::createFeatureBasedContext( QgsFeature(), fields ) );
}
