1 /* 2 * Copyright (c) 2005, 2017, 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.SourceVersion; 30 import javax.lang.model.element.*; 31 import static javax.lang.model.SourceVersion.*; 32 33 34 /** 35 * A skeletal visitor of program elements with default behavior 36 * appropriate for the {@link SourceVersion#RELEASE_6 RELEASE_6} 37 * source version. 38 * 39 * <p> <b>WARNING:</b> The {@code ElementVisitor} interface 40 * implemented by this class may have methods added to it in the 41 * future to accommodate new, currently unknown, language structures 42 * added to future versions of the Java™ programming language. 43 * Therefore, methods whose names begin with {@code "visit"} may be 44 * added to this class in the future; to avoid incompatibilities, 45 * classes which extend this class should not declare any instance 46 * methods with names beginning with {@code "visit"}. 47 * 48 * <p>When such a new visit method is added, the default 49 * implementation in this class will be to call the {@link 50 * #visitUnknown visitUnknown} method. A new abstract element visitor 51 * class will also be introduced to correspond to the new language 52 * level; this visitor will have different default behavior for the 53 * visit method in question. When the new visitor is introduced, all 54 * or portions of this visitor may be deprecated. 55 * 56 * @param <R> the return type of this visitor's methods. Use {@link 57 * Void} for visitors that do not need to return results. 58 * @param <P> the type of the additional parameter to this visitor's 59 * methods. Use {@code Void} for visitors that do not need an 60 * additional parameter. 61 * 62 * @author Joseph D. Darcy 63 * @author Scott Seligman 64 * @author Peter von der Ahé 65 * 66 * @see AbstractElementVisitor7 67 * @see AbstractElementVisitor8 68 * @see AbstractElementVisitor9 69 * @since 1.6 70 */ 71 @SupportedSourceVersion(RELEASE_6) 72 public abstract class AbstractElementVisitor6<R, P> implements ElementVisitor<R, P> { 73 /** 74 * Constructor for concrete subclasses to call. 75 * @deprecated Release 6 is obsolete; update to a visitor for a newer 76 * release level. 77 */ 78 @Deprecated(since="9") 79 protected AbstractElementVisitor6(){} 80 81 /** 82 * Visits any program element as if by passing itself to that 83 * element's {@link Element#accept accept} method. The invocation 84 * {@code v.visit(elem, p)} is equivalent to {@code elem.accept(v, 85 * p)}. 86 * 87 * @param e the element to visit 88 * @param p a visitor-specified parameter 89 * @return a visitor-specified result 90 */ 91 public final R visit(Element e, P p) { 92 return e.accept(this, p); 93 } 94 95 /** 96 * Visits any program element as if by passing itself to that 97 * element's {@link Element#accept accept} method and passing 98 * {@code null} for the additional parameter. The invocation 99 * {@code v.visit(elem)} is equivalent to {@code elem.accept(v, 100 * null)}. 101 * 102 * @param e the element to visit 103 * @return a visitor-specified result 104 */ 105 public final R visit(Element e) { 106 return e.accept(this, null); 107 } 108 109 /** 110 * {@inheritDoc} 111 * 112 * @implSpec The default implementation of this method in 113 * {@code AbstractElementVisitor6} will always throw 114 * {@code new UnknownElementException(e, p)}. 115 * This behavior is not required of a subclass. 116 * 117 * @param e {@inheritDoc} 118 * @param p {@inheritDoc} 119 * @return a visitor-specified result 120 * @throws UnknownElementException 121 * a visitor implementation may optionally throw this exception 122 */ 123 @Override 124 public R visitUnknown(Element e, P p) { 125 throw new UnknownElementException(e, p); 126 } 127 128 /** 129 * {@inheritDoc} 130 * 131 * @implSpec Visits a {@code ModuleElement} by calling {@code 132 * visitUnknown}. 133 * 134 * @param e {@inheritDoc} 135 * @param p {@inheritDoc} 136 * @return the result of {@code visitUnknown} 137 * 138 * @since 9 139 * @spec JPMS 140 */ 141 @Override 142 public R visitModule(ModuleElement e, P p) { 143 // Use implementation from interface default method 144 return ElementVisitor.super.visitModule(e, p); 145 } 146 }