jdk8-mips64-public/langtools: src/share/classes/javax/lang/model/util/SimpleElementVisitor6.java@30c36e23f154

     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  */

    26 package javax.lang.model.util;

    28 import javax.lang.model.element.*;

    29 import javax.annotation.processing.SupportedSourceVersion;

    30 import static javax.lang.model.element.ElementKind.*;

    31 import javax.lang.model.SourceVersion;

    32 import static javax.lang.model.SourceVersion.*;

    35 /**

    36  * A simple visitor of program elements with default behavior

    37  * appropriate for the {@link SourceVersion#RELEASE_6 RELEASE_6}

    38  * source version.

    39  *

    40  * Visit methods corresponding to {@code RELEASE_6} language

    41  * constructs call {@link #defaultAction defaultAction}, passing their

    42  * arguments to {@code defaultAction}'s corresponding parameters.

    43  *

    44  * For constructs introduced in {@code RELEASE_7} and later, {@code

    45  * visitUnknown} is called instead.

    46  *

    47  * <p> Methods in this class may be overridden subject to their

    48  * general contract.  Note that annotating methods in concrete

    49  * subclasses with {@link java.lang.Override @Override} will help

    50  * ensure that methods are overridden as intended.

    51  *

    52  * <p> <b>WARNING:</b> The {@code ElementVisitor} interface

    53  * implemented by this class may have methods added to it in the

    54  * future to accommodate new, currently unknown, language structures

    55  * added to future versions of the Java&trade; programming language.

    56  * Therefore, methods whose names begin with {@code "visit"} may be

    57  * added to this class in the future; to avoid incompatibilities,

    58  * classes which extend this class should not declare any instance

    59  * methods with names beginning with {@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 simple element visitor

    64  * class will also be introduced to correspond to the new language

    65  * level; this visitor will have different default behavior for the

    66  * visit method in question.  When the new visitor is introduced, all

    67  * or portions of this visitor may be deprecated.

    68  *

    69  * @param <R> the return type of this visitor's methods.  Use {@code Void}

    70  *             for visitors that do not need to return results.

    71  * @param <P> the type of the additional parameter to this visitor's methods.  Use {@code Void}

    72  *              for visitors that do not need an additional parameter.

    73  *

    74  * @author Joseph D. Darcy

    75  * @author Scott Seligman

    76  * @author Peter von der Ah&eacute;

    77  *

    78  * @see SimpleElementVisitor7

    79  * @see SimpleElementVisitor8

    80  * @since 1.6

    81  */

    82 @SupportedSourceVersion(RELEASE_6)

    83 public class SimpleElementVisitor6<R, P> extends AbstractElementVisitor6<R, P> {

    84     /**

    85      * Default value to be returned; {@link #defaultAction

    86      * defaultAction} returns this value unless the method is

    87      * overridden.

    88      */

    89     protected final R DEFAULT_VALUE;

    91     /**

    92      * Constructor for concrete subclasses; uses {@code null} for the

    93      * default value.

    94      */

    95     protected SimpleElementVisitor6(){

    96         DEFAULT_VALUE = null;

    97     }

    99     /**

   100      * Constructor for concrete subclasses; uses the argument for the

   101      * default value.

   102      *

   103      * @param defaultValue the value to assign to {@link #DEFAULT_VALUE}

   104      */

   105     protected SimpleElementVisitor6(R defaultValue){

   106         DEFAULT_VALUE = defaultValue;

   107     }

   108     /**

   109      * The default action for visit methods.  The implementation in

   110      * this class just returns {@link #DEFAULT_VALUE}; subclasses will

   111      * commonly override this method.

   112      *

   113      * @param e the element to process

   114      * @param p a visitor-specified parameter

   115      * @return {@code DEFAULT_VALUE} unless overridden

   116      */

   117     protected R defaultAction(Element e, P p) {

   118         return DEFAULT_VALUE;

   119     }

   121     /**

   122      * {@inheritDoc} This implementation calls {@code defaultAction}.

   123      *

   124      * @param e {@inheritDoc}

   125      * @param p {@inheritDoc}

   126      * @return  the result of {@code defaultAction}

   127      */

   128     public R visitPackage(PackageElement e, P p) {

   129         return defaultAction(e, p);

   130     }

   132     /**

   133      * {@inheritDoc} This implementation calls {@code defaultAction}.

   134      *

   135      * @param e {@inheritDoc}

   136      * @param p {@inheritDoc}

   137      * @return  the result of {@code defaultAction}

   138      */

   139     public R visitType(TypeElement e, P p) {

   140         return defaultAction(e, p);

   141     }

   143     /**

   144      * {@inheritDoc}

   145      *

   146      * This implementation calls {@code defaultAction}, unless the

   147      * element is a {@code RESOURCE_VARIABLE} in which case {@code

   148      * visitUnknown} is called.

   149      *

   150      * @param e {@inheritDoc}

   151      * @param p {@inheritDoc}

   152      * @return  the result of {@code defaultAction} or {@code visitUnknown}

   153      */

   154     public R visitVariable(VariableElement e, P p) {

   155         if (e.getKind() != ElementKind.RESOURCE_VARIABLE)

   156             return defaultAction(e, p);

   157         else

   158             return visitUnknown(e, p);

   159     }

   161     /**

   162      * {@inheritDoc} This implementation calls {@code defaultAction}.

   163      *

   164      * @param e {@inheritDoc}

   165      * @param p {@inheritDoc}

   166      * @return  the result of {@code defaultAction}

   167      */

   168     public R visitExecutable(ExecutableElement e, P p) {

   169         return defaultAction(e, p);

   170     }

   172     /**

   173      * {@inheritDoc} This implementation calls {@code defaultAction}.

   174      *

   175      * @param e {@inheritDoc}

   176      * @param p {@inheritDoc}

   177      * @return  the result of {@code defaultAction}

   178      */

   179     public R visitTypeParameter(TypeParameterElement e, P p) {

   180         return defaultAction(e, p);

   181     }

   182 }

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