1 /*
   2  * Copyright (c) 2010, 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.annotation.processing.SupportedSourceVersion;
  29 import javax.lang.model.type.*;
  30 
  31 import static javax.lang.model.SourceVersion.*;
  32 
  33 /**
  34  * A skeletal visitor of types with default behavior appropriate for
  35  * the {@link javax.lang.model.SourceVersion#RELEASE_7 RELEASE_7}
  36  * source version.
  37  *
  38  * <p> <b>WARNING:</b> The {@code TypeVisitor} interface implemented
  39  * by this class may have methods added to it in the future to
  40  * accommodate new, currently unknown, language structures added to
  41  * future versions of the Java&trade; programming language.
  42  * Therefore, methods whose names begin with {@code "visit"} may be
  43  * added to this class in the future; to avoid incompatibilities,
  44  * classes which extend this class should not declare any instance
  45  * methods with names beginning with {@code "visit"}.
  46  *
  47  * <p>When such a new visit method is added, the default
  48  * implementation in this class will be to call the {@link
  49  * #visitUnknown visitUnknown} method.  A new abstract type visitor
  50  * class will also be introduced to correspond to the new language
  51  * level; this visitor will have different default behavior for the
  52  * visit method in question.  When the new visitor is introduced, all
  53  * or portions of this visitor may be deprecated.
  54  *
  55  * <p>Note that adding a default implementation of a new visit method
  56  * in a visitor class will occur instead of adding a <em>default
  57  * method</em> directly in the visitor interface since a Java SE 8
  58  * language feature cannot be used to this version of the API since
  59  * this version is required to be runnable on Java SE 7
  60  * implementations.  Future versions of the API that are only required
  61  * to run on Java SE 8 and later may take advantage of default methods
  62  * in this situation.
  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  * @see AbstractTypeVisitor6
  71  * @see AbstractTypeVisitor8
  72  * @see AbstractTypeVisitor9
  73  * @since 1.7
  74  */
  75 @SuppressWarnings("deprecation") // Superclass deprecated
  76 @SupportedSourceVersion(RELEASE_7)
  77 public abstract class AbstractTypeVisitor7<R, P> extends AbstractTypeVisitor6<R, P> {
  78     /**
  79      * Constructor for concrete subclasses to call.
  80      */
  81     protected AbstractTypeVisitor7() {
  82         super();
  83     }
  84 
  85     /**
  86      * Visits a {@code UnionType} in a manner defined by a subclass.
  87      *
  88      * @param t  {@inheritDoc}
  89      * @param p  {@inheritDoc}
  90      * @return the result of the visit as defined by a subclass
  91      */
  92     @Override
  93     public abstract R visitUnion(UnionType t, P p);
  94 }