// Reverse Polish Notation, abs.k // © 2001, Michael Piefel <piefel@informatik.hu-berlin.de> // The abstract syntax of our expressions line: Line(expression); term: Number(integer) | Ident(casestring); expression: Term( term ) | Plus( expression expression ) | Mul( expression expression ) | Minus( expression expression ) | Div( expression expression ) | Div2( expression casestring expression ) ;