import java.util.*;
import edu.neu.ccs.demeterf.*;
import edu.neu.ccs.demeter.dj.*;

Main = <programs> PList(PathSpec) EOF. 
PathSpec : Compound | Simple.
Compound : Unary | Binary.
Unary : Complement.
Complement = *l "(not" + <first> PathSpec - *l ")".
Binary : Join | Merge | Intersection common
  + <first> PathSpec <second> PathSpec - *l ")".
Join = *l "(join".
Merge = *l "(merge".
Intersection = *l "(intersect".
Simple = *l "->" <source> Node <target> Node.
Path = <source> Node <middle> PList(Node) <target> Node.
PList(S) ~ "(" {S} ")".

WfCheck = extends IDb.
WfCheckExperiment = extends IDb.
ComplementMerge = extends IDf.

visitor WellFormedVis = .
visitor WfVisitor = <wf> boolean.


Node = <v> Ident.