Package net.sourceforge.pmd.lang.ast

Interface AstVisitor<P,R>

Type Parameters:
P - Parameter type of the visit method
R - Return type of the visit method
All Known Implementing Classes:
AstVisitorBase
public interface AstVisitor<P,R>
Root interface for AST visitors. Language modules publish a subinterface with one separate visit method for each type of node in the language, eg JavaVisitor.

Usually you never want to call visit methods manually, instead calling Node::acceptVisitor, which then dispatches to the most specific method of the visitor instance.

Use Void as a type parameter if you don't want a parameter type or a return type.

  • Method Summary

    Modifier and Type
    Method
    Description
    default R
    cannotVisit(Node node, P param)
    Called by a node when it detects that the visitor is not of the language it is used to visiting.
    R
    visitNode(Node node, P param)
    Visit a node.

  • Method Details

    • cannotVisit

      default R cannotVisit(Node node, P param)
      Called by a node when it detects that the visitor is not of the language it is used to visiting. If a visitor wants to visit nodes for several languages, it should provide a useful implementation of this method. The default implementation throws
      Parameters:
      node - Node calling back this method
      param - Parameter of the visit
      Returns:
      A value (or may throw)

    • visitNode

      R visitNode(Node node, P param)
      Visit a node. This method is dispatched statically, you should use Node.acceptVisitor(AstVisitor, Object) if you want to call the most specific method instead.
      Parameters:
      node - Node to visit
      param - Parameter
      Returns:
      Some result