Consider the following class dictionary,
behavior file, input and output.
Find the UNKNOWNs.

// Neven-xpath.pdf
import edu.neu.ccs.demeter.dj.*;
import java.util.*;

XPath = List(Exp).
Exp : Simple | BinaryCompound | UnaryCompound.
Simple : ElementTest | WildCard.
BinaryCompound = "(" BOp <arg1> Exp <arg2> Exp ")".
UnaryCompound = "{-{" UOp <arg1> Exp "}-}".
BOp : Disjunction | Child | Descendant | Filter.
UOp : Chi | Des.
Chi = "/".
Des = "desc".
Disjunction = "|".
Child = "/". 
Descendant = "desc" .
Filter = "filt".
ElementTest = Name.
WildCard = "*".
Name = Ident.

Main = <s> String.
List(S) ~ "(" {S} ")".

CountingVisitor = <c> int  extends Visitor .

Behavior file:
=================================================


Main {
  public static void main(String args[]) throws Exception {{
    XPath m = XPath.parse(System.in);
    // m.display();
    ClassGraph cgfull = new ClassGraph(true, false);
    ClassGraph cg = new ClassGraph(cgfull,
      "from XPath bypassing -> *,tail,* to *");
    Visitor countingVis = new CountingVisitor();

    Integer i1 = (Integer) cg.traverse(m, 
      "from XPath via BinaryCompound to Disjunction",
      countingVis);
    System.out.println(i1.intValue() + " disjunction in binary ");
    System.out.println();

    Integer i2 = (Integer) cg.traverse(m, 
      "from XPath to Disjunction",
      countingVis);
    System.out.println(i2.intValue() + " disjunctions ");
    System.out.println();

    List v;

    v = cg.gather(
      m,
      "from XPath via UnaryCompound to Disjunction");
    System.out.println(v.size() + " list length disjunction in unary ");

    v = cg.gather(
      m,
      "from XPath via BinaryCompound to Chi");
    System.out.println(v.size() + " list length Chi in binary ");

    v = cg.gather(
      m,
      "from XPath bypassing BinaryCompound to UnaryCompound");
    System.out.println(v.size() + " list length Unary bypassing Binary");
    System.out.println("done");
  }}
}

CountingVisitor {
  {{
  public void start() {c = 0; }
  // public void before(UnaryCompound host){
  //   System.out.println(host + " UnaryCompound visited");
  // }
  public void before(Disjunction host){
    // System.out.println(c + " Disjunction value of c");
    c++;
  }
  public Object getReturnValue() { return new Integer(c);}
  }}
}

XPath {
 void display() to * (DisplayVisitor); 
}

input:
==================================================


(
a
*
{-{/ {-{ /x }-} }-}
(| (/ p q) {-{ /y }-})
{-{/ (| x y)}-}
(/ a (| b c))
(/ 
  a 
  (desc
    b 
    (filt c {-{desc (| x (| y x))}-})
  ) 
)
{-{ / t }-}
)

output:
==================================================
Reading project file program.prj...
Running the test...
5 disjunction in binary 

5 disjunctions 

3 list length disjunction in unary 
1 list length Chi in binary 
4 list length Unary bypassing Binary
done