1 /* 2 * Copyright (c) 2005, 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.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 * @see SimpleTypeVisitor9 89 * @since 1.6 90 */ 91 @SupportedSourceVersion(RELEASE_6) 92 public class SimpleTypeVisitor6<R, P> extends AbstractTypeVisitor6<R, P> { 93 /** 94 * Default value to be returned; {@link #defaultAction 95 * defaultAction} returns this value unless the method is 96 * overridden. 97 */ 98 protected final R DEFAULT_VALUE; 99 100 /** 101 * Constructor for concrete subclasses; uses {@code null} for the 102 * default value. 103 * @deprecated Release 6 is obsolete; update to a visitor for a newer 104 * release level. 105 */ 106 @Deprecated 107 protected SimpleTypeVisitor6(){ 108 DEFAULT_VALUE = null; 109 } 110 111 /** 112 * Constructor for concrete subclasses; uses the argument for the 113 * default value. 114 * 115 * @param defaultValue the value to assign to {@link #DEFAULT_VALUE} 116 * @deprecated Release 6 is obsolete; update to a visitor for a newer 117 * release level. 118 */ 119 @Deprecated 120 protected SimpleTypeVisitor6(R defaultValue){ 121 DEFAULT_VALUE = defaultValue; 122 } 123 124 /** 125 * The default action for visit methods. The implementation in 126 * this class just returns {@link #DEFAULT_VALUE}; subclasses will 127 * commonly override this method. 128 * 129 * @param e the type to process 130 * @param p a visitor-specified parameter 131 * @return {@code DEFAULT_VALUE} unless overridden 132 */ 133 protected R defaultAction(TypeMirror e, P p) { 134 return DEFAULT_VALUE; 135 } 136 137 /** 138 * {@inheritDoc} This implementation calls {@code defaultAction}. 139 * 140 * @param t {@inheritDoc} 141 * @param p {@inheritDoc} 142 * @return the result of {@code defaultAction} 143 */ 144 public R visitPrimitive(PrimitiveType t, P p) { 145 return defaultAction(t, p); 146 } 147 148 /** 149 * {@inheritDoc} This implementation calls {@code defaultAction}. 150 * 151 * @param t {@inheritDoc} 152 * @param p {@inheritDoc} 153 * @return the result of {@code defaultAction} 154 */ 155 public R visitNull(NullType t, P p){ 156 return defaultAction(t, p); 157 } 158 159 /** 160 * {@inheritDoc} This implementation calls {@code defaultAction}. 161 * 162 * @param t {@inheritDoc} 163 * @param p {@inheritDoc} 164 * @return the result of {@code defaultAction} 165 */ 166 public R visitArray(ArrayType t, P p){ 167 return defaultAction(t, p); 168 } 169 170 /** 171 * {@inheritDoc} This implementation calls {@code defaultAction}. 172 * 173 * @param t {@inheritDoc} 174 * @param p {@inheritDoc} 175 * @return the result of {@code defaultAction} 176 */ 177 public R visitDeclared(DeclaredType t, P p){ 178 return defaultAction(t, p); 179 } 180 181 /** 182 * {@inheritDoc} This implementation calls {@code defaultAction}. 183 * 184 * @param t {@inheritDoc} 185 * @param p {@inheritDoc} 186 * @return the result of {@code defaultAction} 187 */ 188 public R visitError(ErrorType t, P p){ 189 return defaultAction(t, p); 190 } 191 192 /** 193 * {@inheritDoc} This implementation calls {@code defaultAction}. 194 * 195 * @param t {@inheritDoc} 196 * @param p {@inheritDoc} 197 * @return the result of {@code defaultAction} 198 */ 199 public R visitTypeVariable(TypeVariable t, P p){ 200 return defaultAction(t, p); 201 } 202 203 /** 204 * {@inheritDoc} This implementation calls {@code defaultAction}. 205 * 206 * @param t {@inheritDoc} 207 * @param p {@inheritDoc} 208 * @return the result of {@code defaultAction} 209 */ 210 public R visitWildcard(WildcardType t, P p){ 211 return defaultAction(t, p); 212 } 213 214 /** 215 * {@inheritDoc} This implementation calls {@code defaultAction}. 216 * 217 * @param t {@inheritDoc} 218 * @param p {@inheritDoc} 219 * @return the result of {@code defaultAction} 220 */ 221 public R visitExecutable(ExecutableType t, P p) { 222 return defaultAction(t, p); 223 } 224 225 /** 226 * {@inheritDoc} This implementation calls {@code defaultAction}. 227 * 228 * @param t {@inheritDoc} 229 * @param p {@inheritDoc} 230 * @return the result of {@code defaultAction} 231 */ 232 public R visitNoType(NoType t, P p){ 233 return defaultAction(t, p); 234 } 235 }