com.github.chrisbrenton.grappa.parsetree.visitors

Interface Visitor

public interface Visitor

Marker interface for visitor instances

All visitor classes should implement this interface.

Methods to visit a given type of node must obey the following conditions:

• they must be public;
• they must have one argument, whose class is a subclass of ParseNode;
• they must be annotated with Subscribe
• they should return void.

For instance:

     public final class MyVisitor
         implements Visitor
     {
         @Subscribe
         public void visitBaseNode(final BaseNode node)
         {
             // code
         }

         @Subscribe
         public void visitSubclassNode(final SubclassNode node)
         {
             // code
         }

         // etc
     }
 

Important note: if your nodes subclass each other, be aware that all @Subscribe methods whose argument is either of the exact class or any superclass of that node will be called. Depending on the situation, this may be either desirable or undesirable.