1 /*
   2  * Copyright (c) 2005, 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.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 defaultAction}, passing their
  40  * arguments to {@code defaultAction}'s corresponding parameters.
  41  *
  42  * For constructs introduced in {@code RELEASE_7} and later, {@code
  43  * visitUnknown} is called instead.
  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 TypeVisitor} interface implemented
  51  * by this class may have methods added to it in the future to
  52  * accommodate new, currently unknown, language structures added to
  53  * future versions of the Java&trade; programming language.
  54  * Therefore, methods whose names begin with {@code "visit"} may be
  55  * added to this class in the future; to avoid incompatibilities,
  56  * classes which extend this class should not declare any instance
  57  * methods with names beginning with {@code "visit"}.
  58  *
  59  * <p>When such a new visit method is added, the default
  60  * implementation in this class will be to call the {@link
  61  * #visitUnknown visitUnknown} method.  A new simple type visitor
  62  * class will also be introduced to correspond to the new language
  63  * level; this visitor will have different default behavior for the
  64  * visit method in question.  When the new visitor is introduced, all
  65  * or portions of this visitor may be deprecated.
  66  *
  67  * @param <R> the return type of this visitor's methods.  Use {@link
  68  *            Void} for visitors that do not need to return results.
  69  * @param <P> the type of the additional parameter to this visitor's
  70  *            methods.  Use {@code Void} for visitors that do not need an
  71  *            additional parameter.
  72  *
  73  * @author Joseph D. Darcy
  74  * @author Scott Seligman
  75  * @author Peter von der Ah&eacute;
  76  *
  77  * @see SimpleTypeVisitor7
  78  * @since 1.6
  79  */
  80 @SupportedSourceVersion(RELEASE_6)
  81 public class SimpleTypeVisitor6<R, P> extends AbstractTypeVisitor6<R, P> {
  82     /**
  83      * Default value to be returned; {@link #defaultAction
  84      * defaultAction} returns this value unless the method is
  85      * overridden.
  86      */
  87     protected final R DEFAULT_VALUE;
  88 
  89     /**
  90      * Constructor for concrete subclasses; uses {@code null} for the
  91      * default value.
  92      */
  93     protected SimpleTypeVisitor6(){
  94         DEFAULT_VALUE = null;
  95     }
  96 
  97     /**
  98      * Constructor for concrete subclasses; uses the argument for the
  99      * default value.
 100      *
 101      * @param defaultValue the value to assign to {@link #DEFAULT_VALUE}
 102      */
 103     protected SimpleTypeVisitor6(R defaultValue){
 104         DEFAULT_VALUE = defaultValue;
 105     }
 106 
 107     /**
 108      * The default action for visit methods.  The implementation in
 109      * this class just returns {@link #DEFAULT_VALUE}; subclasses will
 110      * commonly override this method.
 111      */
 112     protected R defaultAction(TypeMirror e, P p) {
 113         return DEFAULT_VALUE;
 114     }
 115 
 116     /**
 117      * {@inheritDoc} This implementation calls {@code defaultAction}.
 118      *
 119      * @param t {@inheritDoc}
 120      * @param p {@inheritDoc}
 121      * @return  the result of {@code defaultAction}
 122      */
 123     public R visitPrimitive(PrimitiveType t, P p) {
 124         return defaultAction(t, p);
 125     }
 126 
 127     /**
 128      * {@inheritDoc} This implementation calls {@code defaultAction}.
 129      *
 130      * @param t {@inheritDoc}
 131      * @param p {@inheritDoc}
 132      * @return  the result of {@code defaultAction}
 133      */
 134     public R visitNull(NullType t, P p){
 135         return defaultAction(t, p);
 136     }
 137 
 138     /**
 139      * {@inheritDoc} This implementation calls {@code defaultAction}.
 140      *
 141      * @param t {@inheritDoc}
 142      * @param p {@inheritDoc}
 143      * @return  the result of {@code defaultAction}
 144      */
 145     public R visitArray(ArrayType t, P p){
 146         return defaultAction(t, p);
 147     }
 148 
 149     /**
 150      * {@inheritDoc} This implementation calls {@code defaultAction}.
 151      *
 152      * @param t {@inheritDoc}
 153      * @param p {@inheritDoc}
 154      * @return  the result of {@code defaultAction}
 155      */
 156     public R visitDeclared(DeclaredType t, P p){
 157         return defaultAction(t, p);
 158     }
 159 
 160     /**
 161      * {@inheritDoc} This implementation calls {@code defaultAction}.
 162      *
 163      * @param t {@inheritDoc}
 164      * @param p {@inheritDoc}
 165      * @return  the result of {@code defaultAction}
 166      */
 167     public R visitError(ErrorType t, P p){
 168         return defaultAction(t, p);
 169     }
 170 
 171     /**
 172      * {@inheritDoc} This implementation calls {@code defaultAction}.
 173      *
 174      * @param t {@inheritDoc}
 175      * @param p {@inheritDoc}
 176      * @return  the result of {@code defaultAction}
 177      */
 178     public R visitTypeVariable(TypeVariable t, P p){
 179         return defaultAction(t, p);
 180     }
 181 
 182     /**
 183      * {@inheritDoc} This implementation calls {@code defaultAction}.
 184      *
 185      * @param t {@inheritDoc}
 186      * @param p {@inheritDoc}
 187      * @return  the result of {@code defaultAction}
 188      */
 189     public R visitWildcard(WildcardType t, P p){
 190         return defaultAction(t, p);
 191     }
 192 
 193     /**
 194      * {@inheritDoc} This implementation calls {@code defaultAction}.
 195      *
 196      * @param t {@inheritDoc}
 197      * @param p {@inheritDoc}
 198      * @return  the result of {@code defaultAction}
 199      */
 200     public R visitExecutable(ExecutableType t, P p) {
 201         return defaultAction(t, p);
 202     }
 203 
 204     /**
 205      * {@inheritDoc} This implementation calls {@code defaultAction}.
 206      *
 207      * @param t {@inheritDoc}
 208      * @param p {@inheritDoc}
 209      * @return  the result of {@code defaultAction}
 210      */
 211     public R visitNoType(NoType t, P p){
 212         return defaultAction(t, p);
 213     }
 214 }