1 /*
   2  * Copyright (c) 2010, 2011 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.lang.model.element.*;
  29 import static javax.lang.model.element.ElementKind.*;
  30 import javax.annotation.processing.SupportedSourceVersion;
  31 import static javax.lang.model.SourceVersion.*;
  32 import javax.lang.model.SourceVersion;
  33 
  34 /**
  35  * A visitor of program elements based on their {@linkplain
  36  * ElementKind kind} with default behavior appropriate for the {@link
  37  * SourceVersion#RELEASE_7 RELEASE_7} source version.  For {@linkplain
  38  * Element elements} <tt><i>XYZ</i></tt> that may have more than one
  39  * kind, the <tt>visit<i>XYZ</i></tt> methods in this class delegate
  40  * to the <tt>visit<i>XYZKind</i></tt> method corresponding to the
  41  * first argument's kind.  The <tt>visit<i>XYZKind</i></tt> methods
  42  * call {@link #defaultAction defaultAction}, passing their arguments
  43  * to {@code defaultAction}'s corresponding parameters.
  44  *
  45  * <p> Methods in this class may be overridden subject to their
  46  * general contract.  Note that annotating methods in concrete
  47  * subclasses with {@link java.lang.Override @Override} will help
  48  * ensure that methods are overridden as intended.
  49  *
  50  * <p> <b>WARNING:</b> The {@code ElementVisitor} interface
  51  * implemented by this class may have methods added to it or the
  52  * {@code ElementKind} {@code enum} used in this case may have
  53  * constants added to it in the future to accommodate new, currently
  54  * unknown, language structures added to future versions of the
  55  * Java&trade; programming language.  Therefore, methods whose names
  56  * begin with {@code "visit"} may be added to this class in the
  57  * future; to avoid incompatibilities, classes which extend this class
  58  * should not declare any instance methods with names beginning with
  59  * {@code "visit"}.
  60  *
  61  * <p>When such a new visit method is added, the default
  62  * implementation in this class will be to call the {@link
  63  * #visitUnknown visitUnknown} method.  A new abstract element kind
  64  * visitor class will also be introduced to correspond to the new
  65  * language level; this visitor will have different default behavior
  66  * for the visit method in question.  When the new visitor is
  67  * introduced, all or portions of this visitor may be deprecated.
  68  *
  69  * @param <R> the return type of this visitor's methods.  Use {@link
  70  *            Void} for visitors that do not need to return results.
  71  * @param <P> the type of the additional parameter to this visitor's
  72  *            methods.  Use {@code Void} for visitors that do not need an
  73  *            additional parameter.
  74  *
  75  * @see ElementKindVisitor6
  76  * @since 1.7
  77  */
  78 @SupportedSourceVersion(RELEASE_7)
  79 public class ElementKindVisitor7<R, P> extends ElementKindVisitor6<R, P> {
  80     /**
  81      * Constructor for concrete subclasses; uses {@code null} for the
  82      * default value.
  83      */
  84     protected ElementKindVisitor7() {
  85         super(null);
  86     }
  87 
  88     /**
  89      * Constructor for concrete subclasses; uses the argument for the
  90      * default value.
  91      *
  92      * @param defaultValue the value to assign to {@link #DEFAULT_VALUE}
  93      */
  94     protected ElementKindVisitor7(R defaultValue) {
  95         super(defaultValue);
  96     }
  97 
  98     /**
  99      * Visits a {@code RESOURCE_VARIABLE} variable element by calling
 100      * {@code defaultAction}.
 101      *
 102      * @param e {@inheritDoc}
 103      * @param p {@inheritDoc}
 104      * @return  the result of {@code defaultAction}
 105      */
 106     @Override
 107     public R visitVariableAsResourceVariable(VariableElement e, P p) {
 108         return defaultAction(e, p);
 109     }
 110 }