1 /* 2 * Copyright (c) 2005, 2013, 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.type.*; 29 import javax.annotation.processing.SupportedSourceVersion; 30 import javax.lang.model.SourceVersion; 31 import static javax.lang.model.SourceVersion.*; 32 33 34 /** 35 * A simple visitor of types with default behavior appropriate for the 36 * {@link SourceVersion#RELEASE_6 RELEASE_6} source version. 37 * 38 * Visit methods corresponding to {@code RELEASE_6} language 39 * constructs call {@link #defaultAction defaultAction}, passing their 40 * arguments to {@code defaultAction}'s corresponding parameters. 41 * 42 * For constructs introduced in {@code RELEASE_7} and later, {@code 43 * visitUnknown} is called instead. 44 * 45 * <p> Methods in this class may be overridden subject to their 46 * general contract. Note that annotating methods in concrete 47 * subclasses with {@link java.lang.Override @Override} will help 48 * ensure that methods are overridden as intended. 49 * 50 * <p> <b>WARNING:</b> The {@code TypeVisitor} interface implemented 51 * by this class may have methods added to it in the future to 52 * accommodate new, currently unknown, language structures added to 53 * future versions of the Java™ programming language. 54 * Therefore, methods whose names begin with {@code "visit"} may be 55 * added to this class in the future; to avoid incompatibilities, 56 * classes which extend this class should not declare any instance 57 * methods with names beginning with {@code "visit"}. 58 * 59 * <p>When such a new visit method is added, the default 60 * implementation in this class will be to call the {@link 61 * #visitUnknown visitUnknown} method. A new simple type visitor 62 * class will also be introduced to correspond to the new language 63 * level; this visitor will have different default behavior for the 64 * visit method in question. When the new visitor is introduced, all 65 * or portions of this visitor may be deprecated. 66 * 67 * <p>Note that adding a default implementation of a new visit method 68 * in a visitor class will occur instead of adding a <em>default 69 * method</em> directly in the visitor interface since a Java SE 8 70 * language feature cannot be used to this version of the API since 71 * this version is required to be runnable on Java SE 7 72 * implementations. Future versions of the API that are only required 73 * to run on Java SE 8 and later may take advantage of default methods 74 * in this situation. 75 * 76 * @param <R> the return type of this visitor's methods. Use {@link 77 * Void} for visitors that do not need to return results. 78 * @param <P> the type of the additional parameter to this visitor's 79 * methods. Use {@code Void} for visitors that do not need an 80 * additional parameter. 81 * 82 * @author Joseph D. Darcy 83 * @author Scott Seligman 84 * @author Peter von der Ahé 85 * 86 * @see SimpleTypeVisitor7 87 * @see SimpleTypeVisitor8 88 * @since 1.6 89 */ 90 @SupportedSourceVersion(RELEASE_6) 91 public class SimpleTypeVisitor6<R, P> extends AbstractTypeVisitor6<R, P> { 92 /** 93 * Default value to be returned; {@link #defaultAction 94 * defaultAction} returns this value unless the method is 95 * overridden. 96 */ 97 protected final R DEFAULT_VALUE; 98 99 /** 100 * Constructor for concrete subclasses; uses {@code null} for the 101 * default value. 102 */ 103 protected SimpleTypeVisitor6(){ 104 DEFAULT_VALUE = null; 105 } 106 107 /** 108 * Constructor for concrete subclasses; uses the argument for the 109 * default value. 110 * 111 * @param defaultValue the value to assign to {@link #DEFAULT_VALUE} 112 */ 113 protected SimpleTypeVisitor6(R defaultValue){ 114 DEFAULT_VALUE = defaultValue; 115 } 116 117 /** 118 * The default action for visit methods. The implementation in 119 * this class just returns {@link #DEFAULT_VALUE}; subclasses will 120 * commonly override this method. 121 * 122 * @param e the type to process 123 * @param p a visitor-specified parameter 124 * @return {@code DEFAULT_VALUE} unless overridden 125 */ 126 protected R defaultAction(TypeMirror e, P p) { 127 return DEFAULT_VALUE; 128 } 129 130 /** 131 * {@inheritDoc} This implementation calls {@code defaultAction}. 132 * 133 * @param t {@inheritDoc} 134 * @param p {@inheritDoc} 135 * @return the result of {@code defaultAction} 136 */ 137 public R visitPrimitive(PrimitiveType t, P p) { 138 return defaultAction(t, p); 139 } 140 141 /** 142 * {@inheritDoc} This implementation calls {@code defaultAction}. 143 * 144 * @param t {@inheritDoc} 145 * @param p {@inheritDoc} 146 * @return the result of {@code defaultAction} 147 */ 148 public R visitNull(NullType t, P p){ 149 return defaultAction(t, p); 150 } 151 152 /** 153 * {@inheritDoc} This implementation calls {@code defaultAction}. 154 * 155 * @param t {@inheritDoc} 156 * @param p {@inheritDoc} 157 * @return the result of {@code defaultAction} 158 */ 159 public R visitArray(ArrayType t, P p){ 160 return defaultAction(t, p); 161 } 162 163 /** 164 * {@inheritDoc} This implementation calls {@code defaultAction}. 165 * 166 * @param t {@inheritDoc} 167 * @param p {@inheritDoc} 168 * @return the result of {@code defaultAction} 169 */ 170 public R visitDeclared(DeclaredType t, P p){ 171 return defaultAction(t, p); 172 } 173 174 /** 175 * {@inheritDoc} This implementation calls {@code defaultAction}. 176 * 177 * @param t {@inheritDoc} 178 * @param p {@inheritDoc} 179 * @return the result of {@code defaultAction} 180 */ 181 public R visitError(ErrorType t, P p){ 182 return defaultAction(t, p); 183 } 184 185 /** 186 * {@inheritDoc} This implementation calls {@code defaultAction}. 187 * 188 * @param t {@inheritDoc} 189 * @param p {@inheritDoc} 190 * @return the result of {@code defaultAction} 191 */ 192 public R visitTypeVariable(TypeVariable t, P p){ 193 return defaultAction(t, p); 194 } 195 196 /** 197 * {@inheritDoc} This implementation calls {@code defaultAction}. 198 * 199 * @param t {@inheritDoc} 200 * @param p {@inheritDoc} 201 * @return the result of {@code defaultAction} 202 */ 203 public R visitWildcard(WildcardType t, P p){ 204 return defaultAction(t, p); 205 } 206 207 /** 208 * {@inheritDoc} This implementation calls {@code defaultAction}. 209 * 210 * @param t {@inheritDoc} 211 * @param p {@inheritDoc} 212 * @return the result of {@code defaultAction} 213 */ 214 public R visitExecutable(ExecutableType t, P p) { 215 return defaultAction(t, p); 216 } 217 218 /** 219 * {@inheritDoc} This implementation calls {@code defaultAction}. 220 * 221 * @param t {@inheritDoc} 222 * @param p {@inheritDoc} 223 * @return the result of {@code defaultAction} 224 */ 225 public R visitNoType(NoType t, P p){ 226 return defaultAction(t, p); 227 } 228 }