1 /* 2 * Copyright (c) 2011, 2018, 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.element.*; 29 import javax.annotation.processing.SupportedSourceVersion; 30 import static javax.lang.model.SourceVersion.*; 31 import javax.lang.model.SourceVersion; 32 33 /** 34 * A visitor of program elements based on their {@linkplain 35 * ElementKind kind} with default behavior appropriate for source 36 * versions {@link SourceVersion#RELEASE_9 RELEASE_9} through {@link 37 * SourceVersion#RELEASE_12 RELEASE_12}. 38 * 39 * For {@linkplain 40 * Element elements} <code><i>Xyz</i></code> that may have more than one 41 * kind, the <code>visit<i>Xyz</i></code> methods in this class delegate 42 * to the <code>visit<i>Xyz</i>As<i>Kind</i></code> method corresponding to the 43 * first argument's kind. The <code>visit<i>Xyz</i>As<i>Kind</i></code> methods 44 * call {@link #defaultAction defaultAction}, passing their arguments 45 * to {@code defaultAction}'s corresponding parameters. 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 or the 54 * {@code ElementKind} {@code enum} used in this case may have 55 * constants added to it in the future to accommodate new, currently 56 * unknown, language structures added to future versions of the 57 * Java™ programming language. Therefore, methods whose names 58 * begin with {@code "visit"} may be added to this class in the 59 * future; to avoid incompatibilities, classes which extend this class 60 * should not declare any instance methods with names beginning with 61 * {@code "visit"}. 62 * 63 * <p>When such a new visit method is added, the default 64 * implementation in this class will be to call the {@link 65 * #visitUnknown visitUnknown} method. A new abstract element kind 66 * visitor class will also be introduced to correspond to the new 67 * language level; this visitor will have different default behavior 68 * for the visit method in question. When the new visitor is 69 * introduced, all or portions of this visitor may be deprecated. 70 * 71 * @param <R> the return type of this visitor's methods. Use {@link 72 * Void} for visitors that do not need to return results. 73 * @param <P> the type of the additional parameter to this visitor's 74 * methods. Use {@code Void} for visitors that do not need an 75 * additional parameter. 76 * 77 * @see ElementKindVisitor6 78 * @see ElementKindVisitor7 79 * @see ElementKindVisitor8 80 * @since 9 81 * @spec JPMS 82 */ 83 @SupportedSourceVersion(RELEASE_12) 84 public class ElementKindVisitor9<R, P> extends ElementKindVisitor8<R, P> { 85 /** 86 * Constructor for concrete subclasses; uses {@code null} for the 87 * default value. 88 */ 89 protected ElementKindVisitor9() { 90 super(null); 91 } 92 93 /** 94 * Constructor for concrete subclasses; uses the argument for the 95 * default value. 96 * 97 * @param defaultValue the value to assign to {@link #DEFAULT_VALUE} 98 */ 99 protected ElementKindVisitor9(R defaultValue) { 100 super(defaultValue); 101 } 102 103 /** 104 * {@inheritDoc} 105 * 106 * @implSpec This implementation calls {@code defaultAction}. 107 * 108 * @param e the element to visit 109 * @param p a visitor-specified parameter 110 * @return the result of {@code defaultAction} 111 */ 112 @Override 113 public R visitModule(ModuleElement e, P p) { 114 return defaultAction(e, p); 115 } 116 }