1 /*
   2  * Copyright (c) 2005, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package javax.lang.model.util;
  27 
  28 import javax.annotation.processing.SupportedSourceVersion;
  29 import javax.lang.model.SourceVersion;
  30 import javax.lang.model.element.*;
  31 import static javax.lang.model.SourceVersion.*;
  32 
  33 
  34 /**
  35  * A skeletal visitor of program elements with default behavior
  36  * appropriate for the {@link SourceVersion#RELEASE_6 RELEASE_6}
  37  * source version.
  38  *
  39  * <p> <b>WARNING:</b> The {@code ElementVisitor} interface
  40  * implemented by this class may have methods added to it in the
  41  * future to accommodate new, currently unknown, language structures
  42  * added to future versions of the Java&trade; programming language.
  43  * Therefore, methods whose names begin with {@code "visit"} may be
  44  * added to this class in the future; to avoid incompatibilities,
  45  * classes which extend this class should not declare any instance
  46  * methods with names beginning with {@code "visit"}.
  47  *
  48  * <p>When such a new visit method is added, the default
  49  * implementation in this class will be to call the {@link
  50  * #visitUnknown visitUnknown} method.  A new abstract element visitor
  51  * class will also be introduced to correspond to the new language
  52  * level; this visitor will have different default behavior for the
  53  * visit method in question.  When the new visitor is introduced, all
  54  * or portions of this visitor may be deprecated.
  55  *
  56  * <p>Note that adding a default implementation of a new visit method
  57  * in a visitor class will occur instead of adding a <em>default
  58  * method</em> directly in the visitor interface since a Java SE 8
  59  * language feature cannot be used to this version of the API since
  60  * this version is required to be runnable on Java SE 7
  61  * implementations.  Future versions of the API that are only required
  62  * to run on Java SE 8 and later may take advantage of default methods
  63  * in this situation.
  64  *
  65  * @param <R> the return type of this visitor's methods.  Use {@link
  66  *            Void} for visitors that do not need to return results.
  67  * @param <P> the type of the additional parameter to this visitor's
  68  *            methods.  Use {@code Void} for visitors that do not need an
  69  *            additional parameter.
  70  *
  71  * @author Joseph D. Darcy
  72  * @author Scott Seligman
  73  * @author Peter von der Ah&eacute;
  74  *
  75  * @see AbstractElementVisitor7
  76  * @see AbstractElementVisitor8
  77  * @see AbstractElementVisitor9
  78  * @since 1.6
  79  * @deprecated Release 6 is obsolete; update to a visitor for a newer
  80  * release level.
  81  */
  82 @Deprecated
  83 @SupportedSourceVersion(RELEASE_6)
  84 public abstract class AbstractElementVisitor6<R, P> implements ElementVisitor<R, P> {
  85     /**
  86      * Constructor for concrete subclasses to call.
  87      */
  88     protected AbstractElementVisitor6(){}
  89 
  90     /**
  91      * Visits any program element as if by passing itself to that
  92      * element's {@link Element#accept accept} method.  The invocation
  93      * {@code v.visit(elem)} is equivalent to {@code elem.accept(v,
  94      * p)}.
  95      *
  96      * @param e  the element to visit
  97      * @param p  a visitor-specified parameter
  98      * @return a visitor-specified result
  99      */
 100     public final R visit(Element e, P p) {
 101         return e.accept(this, p);
 102     }
 103 
 104     /**
 105      * Visits any program element as if by passing itself to that
 106      * element's {@link Element#accept accept} method and passing
 107      * {@code null} for the additional parameter.  The invocation
 108      * {@code v.visit(elem)} is equivalent to {@code elem.accept(v,
 109      * null)}.
 110      *
 111      * @param e  the element to visit
 112      * @return a visitor-specified result
 113      */
 114     public final R visit(Element e) {
 115         return e.accept(this, null);
 116     }
 117 
 118     /**
 119      * {@inheritDoc}
 120      *
 121      * <p> The default implementation of this method in
 122      * {@code AbstractElementVisitor6} will always throw
 123      * {@code UnknownElementException}.
 124      * This behavior is not required of a subclass.
 125      *
 126      * @param e  the element to visit
 127      * @param p  a visitor-specified parameter
 128      * @return a visitor-specified result
 129      * @throws UnknownElementException
 130      *          a visitor implementation may optionally throw this exception
 131      */
 132     public R visitUnknown(Element e, P p) {
 133         throw new UnknownElementException(e, p);
 134     }
 135 
 136     /**
 137      * Visits a {@code ModuleElement} by calling {@code
 138      * visitUnknown}.
 139 
 140      * @param e  {@inheritDoc}
 141      * @param p  {@inheritDoc}
 142      * @return the result of {@code visitUnknown}
 143      *
 144      * @since 9
 145      */
 146     @Override
 147     public R visitModule(ModuleElement e, P p) {
 148         return visitUnknown(e, p);
 149     }
 150 }