Mercurial > jdk8-mips64-public > langtools / file revision

 /*

  * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.  Oracle designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Oracle in the LICENSE file that accompanied this code.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  */

 package javax.lang.model.util;

 import javax.lang.model.element.*;

 import javax.annotation.processing.SupportedSourceVersion;

 import javax.lang.model.SourceVersion;

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

 /**

  * A simple visitor of program elements with default behavior

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

  * source version.

  *

  * Visit methods corresponding to {@code RELEASE_6} language

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

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

  *

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

  * visitUnknown} is called instead.

  *

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

  * general contract.  Note that annotating methods in concrete

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

  * ensure that methods are overridden as intended.

  *

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

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

  * future to accommodate new, currently unknown, language structures

  * added to future versions of the Java™ programming language.

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

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

  * classes which extend this class should not declare any instance

  * methods with names beginning with {@code "visit"}.

  *

  * <p>When such a new visit method is added, the default

  * implementation in this class will be to call the {@link

  * #visitUnknown visitUnknown} method.  A new simple element visitor

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

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

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

  * or portions of this visitor may be deprecated.

  *

  * <p>Note that adding a default implementation of a new visit method

  * in a visitor class will occur instead of adding a <em>default

  * method</em> directly in the visitor interface since a Java SE 8

  * language feature cannot be used to this version of the API since

  * this version is required to be runnable on Java SE 7

  * implementations.  Future versions of the API that are only required

  * to run on Java SE 8 and later may take advantage of default methods

  * in this situation.

  *

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

  *             for visitors that do not need to return results.

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

  *              for visitors that do not need an additional parameter.

  *

  * @author Joseph D. Darcy

  * @author Scott Seligman

  * @author Peter von der Ahé

  *

  * @see SimpleElementVisitor7

  * @see SimpleElementVisitor8

  * @since 1.6

  */

 @SupportedSourceVersion(RELEASE_6)

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

     /**

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

      * defaultAction} returns this value unless the method is

      * overridden.

      */

     protected final R DEFAULT_VALUE;

     /**

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

      * default value.

      */

     protected SimpleElementVisitor6(){

         DEFAULT_VALUE = null;

     }

     /**

      * Constructor for concrete subclasses; uses the argument for the

      * default value.

      *

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

      */

     protected SimpleElementVisitor6(R defaultValue){

         DEFAULT_VALUE = defaultValue;

     }

     /**

      * The default action for visit methods.  The implementation in

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

      * commonly override this method.

      *

      * @param e the element to process

      * @param p a visitor-specified parameter

      * @return {@code DEFAULT_VALUE} unless overridden

      */

     protected R defaultAction(Element e, P p) {

         return DEFAULT_VALUE;

     }

     /**

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

      *

      * @param e {@inheritDoc}

      * @param p {@inheritDoc}

      * @return  the result of {@code defaultAction}

      */

     public R visitPackage(PackageElement e, P p) {

         return defaultAction(e, p);

     }

     /**

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

      *

      * @param e {@inheritDoc}

      * @param p {@inheritDoc}

      * @return  the result of {@code defaultAction}

      */

     public R visitType(TypeElement e, P p) {

         return defaultAction(e, p);

     }

     /**

      * {@inheritDoc}

      *

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

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

      * visitUnknown} is called.

      *

      * @param e {@inheritDoc}

      * @param p {@inheritDoc}

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

      */

     public R visitVariable(VariableElement e, P p) {

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

             return defaultAction(e, p);

         else

             return visitUnknown(e, p);

     }

     /**

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

      *

      * @param e {@inheritDoc}

      * @param p {@inheritDoc}

      * @return  the result of {@code defaultAction}

      */

     public R visitExecutable(ExecutableElement e, P p) {

         return defaultAction(e, p);

     }

     /**

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

      *

      * @param e {@inheritDoc}

      * @param p {@inheritDoc}

      * @return  the result of {@code defaultAction}

      */

     public R visitTypeParameter(TypeParameterElement e, P p) {

         return defaultAction(e, p);

     }

 }