1 /* 2 * Copyright (c) 2005, 2010, 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.element.ElementKind.*; 31 import javax.lang.model.SourceVersion; 32 import static javax.lang.model.SourceVersion.*; 33 34 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}, passing their arguments to 42 * {@code defaultAction}'s corresponding parameters. 43 * 44 * <p> Methods in this class may be overridden subject to their 45 * general contract. Note that annotating methods in concrete 46 * subclasses with {@link java.lang.Override @Override} will help 47 * ensure that methods are overridden as intended. 48 * 49 * <p> <b>WARNING:</b> The {@code ElementVisitor} interface 50 * implemented by this class may have methods added to it in the 51 * future to accommodate new, currently unknown, language structures 52 * added to future versions of the Java™ programming language. 53 * Therefore, methods whose names begin with {@code "visit"} may be 54 * added to this class in the future; to avoid incompatibilities, 55 * classes which extend this class should not declare any instance 56 * methods with names beginning with {@code "visit"}. 57 * 58 * <p>When such a new visit method is added, the default 59 * implementation in this class will be to call the {@link 60 * #visitUnknown visitUnknown} method. A new simple element visitor 61 * class will also be introduced to correspond to the new language 62 * level; this visitor will have different default behavior for the 63 * visit method in question. When the new visitor is introduced, all 64 * or portions of this visitor may be deprecated. 65 * 66 * @param <R> the return type of this visitor's methods. Use {@code Void} 67 * for visitors that do not need to return results. 68 * @param <P> the type of the additional parameter to this visitor's methods. Use {@code Void} 69 * for visitors that do not need an additional parameter. 70 * 71 * @author Joseph D. Darcy 72 * @author Scott Seligman 73 * @author Peter von der Ahé 74 * 75 * @see SimpleElementVisitor7 76 * @since 1.6 77 */ 78 @SupportedSourceVersion(RELEASE_6) 79 public class SimpleElementVisitor6<R, P> extends AbstractElementVisitor6<R, P> { 80 /** 81 * Default value to be returned; {@link #defaultAction 82 * defaultAction} returns this value unless the method is 83 * overridden. 84 */ 85 protected final R DEFAULT_VALUE; 86 87 /** 88 * Constructor for concrete subclasses; uses {@code null} for the 89 * default value. 90 */ 91 protected SimpleElementVisitor6(){ 92 DEFAULT_VALUE = null; 93 } 94 95 /** 96 * Constructor for concrete subclasses; uses the argument for the 97 * default value. 98 * 99 * @param defaultValue the value to assign to {@link #DEFAULT_VALUE} 100 */ 101 protected SimpleElementVisitor6(R defaultValue){ 102 DEFAULT_VALUE = defaultValue; 103 } 104 /** 105 * The default action for visit methods. The implementation in 106 * this class just returns {@link #DEFAULT_VALUE}; subclasses will 107 * commonly override this method. 108 * 109 * @param e the element to process 110 * @param p a visitor-specified parameter 111 * @return {@code DEFAULT_VALUE} unless overridden 112 */ 113 protected R defaultAction(Element e, P p) { 114 return DEFAULT_VALUE; 115 } 116 117 /** 118 * {@inheritDoc} This implementation calls {@code defaultAction}. 119 * 120 * @param e {@inheritDoc} 121 * @param p {@inheritDoc} 122 * @return the result of {@code defaultAction} 123 */ 124 public R visitPackage(PackageElement e, P p) { 125 return defaultAction(e, p); 126 } 127 128 /** 129 * {@inheritDoc} This implementation calls {@code defaultAction}. 130 * 131 * @param e {@inheritDoc} 132 * @param p {@inheritDoc} 133 * @return the result of {@code defaultAction} 134 */ 135 public R visitType(TypeElement e, P p) { 136 return defaultAction(e, p); 137 } 138 139 /** 140 * {@inheritDoc} This implementation calls {@code defaultAction}. 141 * 142 * @param e {@inheritDoc} 143 * @param p {@inheritDoc} 144 * @return the result of {@code defaultAction} 145 */ 146 public R visitVariable(VariableElement e, P p) { 147 return defaultAction(e, p); 148 } 149 150 /** 151 * {@inheritDoc} This implementation calls {@code defaultAction}. 152 * 153 * @param e {@inheritDoc} 154 * @param p {@inheritDoc} 155 * @return the result of {@code defaultAction} 156 */ 157 public R visitExecutable(ExecutableElement e, P p) { 158 return defaultAction(e, p); 159 } 160 161 /** 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 visitTypeParameter(TypeParameterElement e, P p) { 169 return defaultAction(e, p); 170 } 171 }