1 /*
   2  * Copyright (c) 2011, 2014, 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 javax.annotation.processing.SupportedSourceVersion;
  30 import static javax.lang.model.SourceVersion.*;
  31 import javax.lang.model.SourceVersion;
  32 
  33 /**
  34  * A visitor of program elements based on their {@linkplain
  35  * ElementKind kind} with default behavior appropriate for the {@link
  36  * SourceVersion#RELEASE_8 RELEASE_8} source version.  For {@linkplain
  37  * Element elements} <code><i>Xyz</i></code> that may have more than one
  38  * kind, the <code>visit<i>Xyz</i></code> methods in this class delegate
  39  * to the <code>visit<i>Xyz</i>As<i>Kind</i></code> method corresponding to the
  40  * first argument's kind.  The <code>visit<i>Xyz</i>As<i>Kind</i></code> methods
  41  * call {@link #defaultAction defaultAction}, passing their arguments
  42  * to {@code defaultAction}'s corresponding parameters.
  43  *
  44  * <p> Methods in this class may be overridden subject to their
  45  * general contract.  Note that annotating methods in concrete
  46  * subclasses with {@link java.lang.Override @Override} will help
  47  * ensure that methods are overridden as intended.
  48  *
  49  * <p> <b>WARNING:</b> The {@code ElementVisitor} interface
  50  * implemented by this class may have methods added to it or the
  51  * {@code ElementKind} {@code enum} used in this case may have
  52  * constants added to it in the future to accommodate new, currently
  53  * unknown, language structures added to future versions of the
  54  * Java&trade; programming language.  Therefore, methods whose names
  55  * begin with {@code "visit"} may be added to this class in the
  56  * future; to avoid incompatibilities, classes which extend this class
  57  * should not declare any instance methods with names beginning with
  58  * {@code "visit"}.
  59  *
  60  * <p>When such a new visit method is added, the default
  61  * implementation in this class will be to call the {@link
  62  * #visitUnknown visitUnknown} method.  A new abstract element kind
  63  * visitor class will also be introduced to correspond to the new
  64  * language level; this visitor will have different default behavior
  65  * for the visit method in question.  When the new visitor is
  66  * introduced, all or portions of this visitor may be deprecated.
  67  *
  68  * @param <R> the return type of this visitor's methods.  Use {@link
  69  *            Void} for visitors that do not need to return results.
  70  * @param <P> the type of the additional parameter to this visitor's
  71  *            methods.  Use {@code Void} for visitors that do not need an
  72  *            additional parameter.
  73  *
  74  * @see ElementKindVisitor6
  75  * @see ElementKindVisitor7
  76  * @see ElementKindVisitor9
  77  * @since 1.8
  78  */
  79 @SupportedSourceVersion(RELEASE_8)
  80 public class ElementKindVisitor8<R, P> extends ElementKindVisitor7<R, P> {
  81     /**
  82      * Constructor for concrete subclasses; uses {@code null} for the
  83      * default value.
  84      */
  85     protected ElementKindVisitor8() {
  86         super(null);
  87     }
  88 
  89     /**
  90      * Constructor for concrete subclasses; uses the argument for the
  91      * default value.
  92      *
  93      * @param defaultValue the value to assign to {@link #DEFAULT_VALUE}
  94      */
  95     protected ElementKindVisitor8(R defaultValue) {
  96         super(defaultValue);
  97     }
  98 }