module PYTHON-VISITOR

syntax K ::= "visit" "(" K "," KLabel ")"

| "visited" "(" KList ")"

| "visiting" "(" KLabel "," KList "," Int "," KLabel ")"

syntax KLabel ::= "returner"

rule visit(Lbl:KLabel(Kl:KList), Visitor:KLabel) => visited(.KList) ~> visiting(Lbl, Kl, 0, Visitor)

rule visit(., Visitor:KLabel) => Visitor((KLabel2KLabel(returner)(.KList)),, -1,, .)

rule (. => Visitor:KLabel((KLabel2KLabel(Lbl:KLabel)(.KList)),, N,, K)) ~> visited(_) ~> visiting(Lbl, (K:K,,Kl:KList => Kl), (N:Int => N +Int 1), Visitor)

rule (visited(K) => .) ~> visited(_,,(.KList => K))

rule visited(Kl:KList) ~> visiting(Lbl:KLabel, .KList, _, Visitor:KLabel) => Visitor((KLabel2KLabel(returner)(.KList)),, -1,, Lbl(Kl))

endmodule