package org.apidesign.visitor;

 public final class Language {

     private Language() { }

     public interface Expression {

         public abstract void visit(Visitor v);

     }

     public interface Plus extends Expression {

         public Expression getFirst();

         public Expression getSecond();

     }

     public interface Number extends Expression {

         public int getValue();

     }

     // BEGIN: visitor.clientprovider.self.v1

     public static abstract class Visitor {

         Visitor() {}

         public static Visitor create(Version10 v) {

             return create10(v);

         }

         public interface Version10 {

             public boolean visitUnknown(Expression e, Visitor self);

             public void visitPlus(Plus s, Visitor self);

             public void visitNumber(Number n, Visitor self);

         }

         public abstract void dispatchPlus(Plus p);

         public abstract void dispatchNumber(Number n);

     }

     // END: visitor.clientprovider.self.v1

     static Visitor create10(final Visitor.Version10 v) {

         return new Visitor() {

             @Override

             public void dispatchPlus(Plus p) {

                 v.visitPlus(p, this);

             }

             @Override

             public void dispatchNumber(Number n) {

                 v.visitNumber(n, this);

             }

         };

     }

 }