func (this *BaseOperator) Evaluate(e ast.Expression, item *dparval.Value) (*dparval.Value, error) {
// first ensure the query is avaliable
item.SetAttachment("query", this.query)
return e.Evaluate(item)
}
func (this *ExpressionSargable) evaluateConstant(e ast.Expression) (*dparval.Value, error) {
return e.Evaluate(dparval.NewValue(map[string]interface{}{}))
}