Douglas Crockford's Top Down Operator Precedence parser, written in ES6
(0 "1" 0) (10 "+" 10) (0 "1" 0) (20 "" 20) (0 "0" 0) reduce: walk down the nodes in highest valued child first order and draw edges from small number to large number (0 "1" 0) (10 "+" 10) (0 "1" 0) (20 "" 20) (0 "0" 0) (0 "1"->"+" 10) (0 "1" 0) (20 "" 20) (0 "0" 0) (0 "1"->"+"<-"1" 0) (20 "" 20) (0 "0" 0) ("1"->"+"<-"1")->("" 20) (0 "0" 0) ("1"->"+"<-"1")->(""<-"0")