23  * questions.
  24  */
  25 
  26 package com.sun.source.tree;
  27 
  28 /**
  29  * A visitor of trees, in the style of the visitor design pattern.
  30  * Classes implementing this interface are used to operate
  31  * on a tree when the kind of tree is unknown at compile time.
  32  * When a visitor is passed to an tree's {@link Tree#accept
  33  * accept} method, the <code>visit<i>Xyz</i></code> method most applicable
  34  * to that tree is invoked.
  35  *
  36  * <p> Classes implementing this interface may or may not throw a
  37  * {@code NullPointerException} if the additional parameter {@code p}
  38  * is {@code null}; see documentation of the implementing class for
  39  * details.
  40  *
  41  * <p> <b>WARNING:</b> It is possible that methods will be added to
  42  * this interface to accommodate new, currently unknown, language
  43  * structures added to future versions of the Java&trade; programming
  44  * language.  Therefore, visitor classes directly implementing this
  45  * interface may be source incompatible with future versions of the
  46  * platform.
  47  *
  48  * @param <R> the return type of this visitor's methods.  Use {@link
  49  *            Void} for visitors that do not need to return results.
  50  * @param <P> the type of the additional parameter to this visitor's
  51  *            methods.  Use {@code Void} for visitors that do not need an
  52  *            additional parameter.
  53  *
  54  * @author Peter von der Ah&eacute;
  55  * @author Jonathan Gibbons
  56  *
  57  * @since 1.6
  58  */
  59 public interface TreeVisitor<R,P> {
  60     /**
  61      * Visits an AnnotatedTypeTree node.
  62      * @param node the node being visited
  63      * @param p a parameter value

  23  * questions.
  24  */
  25 
  26 package com.sun.source.tree;
  27 
  28 /**
  29  * A visitor of trees, in the style of the visitor design pattern.
  30  * Classes implementing this interface are used to operate
  31  * on a tree when the kind of tree is unknown at compile time.
  32  * When a visitor is passed to an tree's {@link Tree#accept
  33  * accept} method, the <code>visit<i>Xyz</i></code> method most applicable
  34  * to that tree is invoked.
  35  *
  36  * <p> Classes implementing this interface may or may not throw a
  37  * {@code NullPointerException} if the additional parameter {@code p}
  38  * is {@code null}; see documentation of the implementing class for
  39  * details.
  40  *
  41  * <p> <b>WARNING:</b> It is possible that methods will be added to
  42  * this interface to accommodate new, currently unknown, language
  43  * structures added to future versions of the Java programming
  44  * language.  Therefore, visitor classes directly implementing this
  45  * interface may be source incompatible with future versions of the
  46  * platform.
  47  *
  48  * @param <R> the return type of this visitor's methods.  Use {@link
  49  *            Void} for visitors that do not need to return results.
  50  * @param <P> the type of the additional parameter to this visitor's
  51  *            methods.  Use {@code Void} for visitors that do not need an
  52  *            additional parameter.
  53  *
  54  * @author Peter von der Ah&eacute;
  55  * @author Jonathan Gibbons
  56  *
  57  * @since 1.6
  58  */
  59 public interface TreeVisitor<R,P> {
  60     /**
  61      * Visits an AnnotatedTypeTree node.
  62      * @param node the node being visited
  63      * @param p a parameter value