Abstract: The disclosed technologies include receiving a selection of an item for which an attribute is to be determined. The attribute is dependent on one or more variable conditions. Data is input that represents a set of rules for determining the attribute. Based on the rules, a parse tree is generated that is usable to determine the attribute based on the one or more variable conditions. The data is parsed and nodes of the parse tree are pre-calculated as values become available. The attribute is determined based on the parsing and pre-calculating. The determined attribute is returned to a requesting process.