TypeKindVisitor7.java revision 2571:10fc81ac75b4
1/* 2 * Copyright (c) 2010, 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 26package javax.lang.model.util; 27 28import javax.lang.model.type.*; 29import javax.annotation.processing.SupportedSourceVersion; 30import static javax.lang.model.SourceVersion.*; 31import javax.lang.model.SourceVersion; 32 33/** 34 * A visitor of types based on their {@linkplain TypeKind kind} with 35 * default behavior appropriate for the {@link SourceVersion#RELEASE_7 36 * RELEASE_7} source version. For {@linkplain 37 * TypeMirror types} <tt><i>XYZ</i></tt> that may have more than one 38 * kind, the <tt>visit<i>XYZ</i></tt> methods in this class delegate 39 * to the <tt>visit<i>XYZKind</i></tt> method corresponding to the 40 * first argument's kind. The <tt>visit<i>XYZKind</i></tt> methods 41 * call {@link #defaultAction defaultAction}, passing their arguments 42 * to {@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 TypeVisitor} interface implemented 50 * by this class may have methods added to it in the future to 51 * accommodate new, currently unknown, language structures added to 52 * 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 type kind visitor class 61 * will also be introduced to correspond to the new language level; 62 * this visitor will have different default behavior for the visit 63 * method in question. When the new visitor is introduced, all or 64 * portions of this visitor may be deprecated. 65 * 66 * <p>Note that adding a default implementation of a new visit method 67 * in a visitor class will occur instead of adding a <em>default 68 * method</em> directly in the visitor interface since a Java SE 8 69 * language feature cannot be used to this version of the API since 70 * this version is required to be runnable on Java SE 7 71 * implementations. Future versions of the API that are only required 72 * to run on Java SE 8 and later may take advantage of default methods 73 * in this situation. 74 * 75 * @param <R> the return type of this visitor's methods. Use {@link 76 * Void} for visitors that do not need to return results. 77 * @param <P> the type of the additional parameter to this visitor's 78 * methods. Use {@code Void} for visitors that do not need an 79 * additional parameter. 80 * 81 * @see TypeKindVisitor6 82 * @see TypeKindVisitor8 83 * @since 1.7 84 */ 85@SuppressWarnings("deprecation") // Superclass deprecated 86@SupportedSourceVersion(RELEASE_7) 87public class TypeKindVisitor7<R, P> extends TypeKindVisitor6<R, P> { 88 /** 89 * Constructor for concrete subclasses to call; uses {@code null} 90 * for the default value. 91 */ 92 protected TypeKindVisitor7() { 93 super(null); 94 } 95 96 /** 97 * Constructor for concrete subclasses to call; uses the argument 98 * for the default value. 99 * 100 * @param defaultValue the value to assign to {@link #DEFAULT_VALUE} 101 */ 102 protected TypeKindVisitor7(R defaultValue) { 103 super(defaultValue); 104 } 105 106 /** 107 * This implementation visits a {@code UnionType} by calling 108 * {@code defaultAction}. 109 * 110 * @param t {@inheritDoc} 111 * @param p {@inheritDoc} 112 * @return the result of {@code defaultAction} 113 */ 114 @Override 115 public R visitUnion(UnionType t, P p) { 116 return defaultAction(t, p); 117 } 118} 119