1 /*
   2  * Copyright (c) 2005, 2010, 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.type.*;
  29 import javax.annotation.processing.SupportedSourceVersion;
  30 import javax.lang.model.SourceVersion;
  31 import static javax.lang.model.SourceVersion.*;
  32 
  33 
  34 /**
  35  * A simple visitor of types with default behavior appropriate for the
  36  * {@link SourceVersion#RELEASE_6 RELEASE_6} source version.
  37  *
  38  * Visit methods corresponding to {@code RELEASE_6} language
  39  * constructs call {@link #defaultAction}, passing their arguments to
  40  * {@code defaultAction}'s corresponding parameters.
  41  *
  42  * <p> Methods in this class may be overridden subject to their
  43  * general contract.  Note that annotating methods in concrete
  44  * subclasses with {@link java.lang.Override @Override} will help
  45  * ensure that methods are overridden as intended.
  46  *
  47  * <p> <b>WARNING:</b> The {@code TypeVisitor} interface implemented
  48  * by this class may have methods added to it in the future to
  49  * accommodate new, currently unknown, language structures added to
  50  * future versions of the Java&trade; programming language.
  51  * Therefore, methods whose names begin with {@code "visit"} may be
  52  * added to this class in the future; to avoid incompatibilities,
  53  * classes which extend this class should not declare any instance
  54  * methods with names beginning with {@code "visit"}.
  55  *
  56  * <p>When such a new visit method is added, the default
  57  * implementation in this class will be to call the {@link
  58  * #visitUnknown visitUnknown} method.  A new simple type visitor
  59  * class will also be introduced to correspond to the new language
  60  * level; this visitor will have different default behavior for the
  61  * visit method in question.  When the new visitor is introduced, all
  62  * or portions of this visitor may be deprecated.
  63  *
  64  * @param <R> the return type of this visitor's methods.  Use {@link
  65  *            Void} for visitors that do not need to return results.
  66  * @param <P> the type of the additional parameter to this visitor's
  67  *            methods.  Use {@code Void} for visitors that do not need an
  68  *            additional parameter.
  69  *
  70  * @author Joseph D. Darcy
  71  * @author Scott Seligman
  72  * @author Peter von der Ah&eacute;
  73  *
  74  * @see SimpleTypeVisitor7
  75  * @since 1.6
  76  */
  77 @SupportedSourceVersion(RELEASE_6)
  78 public class SimpleTypeVisitor6<R, P> extends AbstractTypeVisitor6<R, P> {
  79     /**
  80      * Default value to be returned; {@link #defaultAction
  81      * defaultAction} returns this value unless the method is
  82      * overridden.
  83      */
  84     protected final R DEFAULT_VALUE;
  85 
  86     /**
  87      * Constructor for concrete subclasses; uses {@code null} for the
  88      * default value.
  89      */
  90     protected SimpleTypeVisitor6(){
  91         DEFAULT_VALUE = null;
  92     }
  93 
  94     /**
  95      * Constructor for concrete subclasses; uses the argument for the
  96      * default value.
  97      *
  98      * @param defaultValue the value to assign to {@link #DEFAULT_VALUE}
  99      */
 100     protected SimpleTypeVisitor6(R defaultValue){
 101         DEFAULT_VALUE = defaultValue;
 102     }
 103 
 104     /**
 105      * The default action for visit methods.  The implementation in
 106      * this class just returns {@link #DEFAULT_VALUE}; subclasses will
 107      * commonly override this method.
 108      */
 109     protected R defaultAction(TypeMirror e, P p) {
 110         return DEFAULT_VALUE;
 111     }
 112 
 113     /**
 114      * {@inheritDoc} This implementation calls {@code defaultAction}.
 115      *
 116      * @param t {@inheritDoc}
 117      * @param p {@inheritDoc}
 118      * @return  the result of {@code defaultAction}
 119      */
 120     public R visitPrimitive(PrimitiveType t, P p) {
 121         return defaultAction(t, p);
 122     }
 123 
 124     /**
 125      * {@inheritDoc} This implementation calls {@code defaultAction}.
 126      *
 127      * @param t {@inheritDoc}
 128      * @param p {@inheritDoc}
 129      * @return  the result of {@code defaultAction}
 130      */
 131     public R visitNull(NullType t, P p){
 132         return defaultAction(t, p);
 133     }
 134 
 135     /**
 136      * {@inheritDoc} This implementation calls {@code defaultAction}.
 137      *
 138      * @param t {@inheritDoc}
 139      * @param p {@inheritDoc}
 140      * @return  the result of {@code defaultAction}
 141      */
 142     public R visitArray(ArrayType t, P p){
 143         return defaultAction(t, p);
 144     }
 145 
 146     /**
 147      * {@inheritDoc} This implementation calls {@code defaultAction}.
 148      *
 149      * @param t {@inheritDoc}
 150      * @param p {@inheritDoc}
 151      * @return  the result of {@code defaultAction}
 152      */
 153     public R visitDeclared(DeclaredType t, P p){
 154         return defaultAction(t, p);
 155     }
 156 
 157     /**
 158      * {@inheritDoc} This implementation calls {@code defaultAction}.
 159      *
 160      * @param t {@inheritDoc}
 161      * @param p {@inheritDoc}
 162      * @return  the result of {@code defaultAction}
 163      */
 164     public R visitError(ErrorType t, P p){
 165         return defaultAction(t, p);
 166     }
 167 
 168     /**
 169      * {@inheritDoc} This implementation calls {@code defaultAction}.
 170      *
 171      * @param t {@inheritDoc}
 172      * @param p {@inheritDoc}
 173      * @return  the result of {@code defaultAction}
 174      */
 175     public R visitTypeVariable(TypeVariable t, P p){
 176         return defaultAction(t, p);
 177     }
 178 
 179     /**
 180      * {@inheritDoc} This implementation calls {@code defaultAction}.
 181      *
 182      * @param t {@inheritDoc}
 183      * @param p {@inheritDoc}
 184      * @return  the result of {@code defaultAction}
 185      */
 186     public R visitWildcard(WildcardType t, P p){
 187         return defaultAction(t, p);
 188     }
 189 
 190     /**
 191      * {@inheritDoc} This implementation calls {@code defaultAction}.
 192      *
 193      * @param t {@inheritDoc}
 194      * @param p {@inheritDoc}
 195      * @return  the result of {@code defaultAction}
 196      */
 197     public R visitExecutable(ExecutableType t, P p) {
 198         return defaultAction(t, p);
 199     }
 200 
 201     /**
 202      * {@inheritDoc} This implementation calls {@code defaultAction}.
 203      *
 204      * @param t {@inheritDoc}
 205      * @param p {@inheritDoc}
 206      * @return  the result of {@code defaultAction}
 207      */
 208     public R visitNoType(NoType t, P p){
 209         return defaultAction(t, p);
 210     }
 211 }