/**
   * Main loop entry.
   *
   * <p>First, it delegates to the super visitClass so we can collect the relevant annotations in an
   * AST tree walk.
   *
   * <p>Second, it calls the visit method on the transformation for each relevant annotation found.
   *
   * @param classNode the class to visit
   */
  public void visitClass(ClassNode classNode) {
    // only descend if we have annotations to look for
    Map<Class<? extends ASTTransformation>, Set<ASTNode>> baseTransforms =
        classNode.getTransforms(phase);
    if (!baseTransforms.isEmpty()) {
      final Map<Class<? extends ASTTransformation>, ASTTransformation> transformInstances =
          new HashMap<Class<? extends ASTTransformation>, ASTTransformation>();
      for (Class<? extends ASTTransformation> transformClass : baseTransforms.keySet()) {
        try {
          transformInstances.put(transformClass, transformClass.newInstance());
        } catch (InstantiationException e) {
          source
              .getErrorCollector()
              .addError(
                  new SimpleMessage(
                      "Could not instantiate Transformation Processor "
                          + transformClass, // + " declared by " +
                                            // annotation.getClassNode().getName(),
                      source));
        } catch (IllegalAccessException e) {
          source
              .getErrorCollector()
              .addError(
                  new SimpleMessage(
                      "Could not instantiate Transformation Processor "
                          + transformClass, // + " declared by " +
                                            // annotation.getClassNode().getName(),
                      source));
        }
      }

      // invert the map, is now one to many
      transforms = new HashMap<ASTNode, List<ASTTransformation>>();
      for (Map.Entry<Class<? extends ASTTransformation>, Set<ASTNode>> entry :
          baseTransforms.entrySet()) {
        for (ASTNode node : entry.getValue()) {
          List<ASTTransformation> list = transforms.get(node);
          if (list == null) {
            list = new ArrayList<ASTTransformation>();
            transforms.put(node, list);
          }
          list.add(transformInstances.get(entry.getKey()));
        }
      }

      targetNodes = new LinkedList<ASTNode[]>();

      // first pass, collect nodes
      super.visitClass(classNode);

      // second pass, call visit on all of the collected nodes
      for (ASTNode[] node : targetNodes) {
        for (ASTTransformation snt : transforms.get(node[0])) {
          if (snt instanceof CompilationUnitAware) {
            ((CompilationUnitAware) snt).setCompilationUnit(context.getCompilationUnit());
          }
          snt.visit(node, source);
        }
      }
    }
  }
 public void visit(ASTNode[] nodes, SourceUnit sourceUnit) {
   ClassNode classNode = (ClassNode) nodes[1];
   classNode.addField(new FieldNode("f3", ACC_PUBLIC, ClassHelper.OBJECT_TYPE, classNode, null));
 }