TypeKindVisitor7.java revision 3884:b6960e2da008 
1/*
2 * Copyright (c) 2010, 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
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} <code><i>Xyz</i></code> that may have more than one
38 * kind, the <code>visit<i>Xyz</i></code> methods in this class delegate
39 * to the <code>visit<i>Xyz</i>As<i>Kind</i></code> method corresponding to the
40 * first argument's kind.  The <code>visit<i>Xyz</i>As<i>Kind</i></code> 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&trade; 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 * @param <R> the return type of this visitor's methods.  Use {@link
67 *            Void} for visitors that do not need to return results.
68 * @param <P> the type of the additional parameter to this visitor's
69 *            methods.  Use {@code Void} for visitors that do not need an
70 *            additional parameter.
71 *
72 * @see TypeKindVisitor6
73 * @see TypeKindVisitor8
74 * @since 1.7
75 */
76@SuppressWarnings("deprecation") // Superclass deprecated
77@SupportedSourceVersion(RELEASE_7)
78public class TypeKindVisitor7<R, P> extends TypeKindVisitor6<R, P> {
79    /**
80     * Constructor for concrete subclasses to call; uses {@code null}
81     * for the default value.
82     */
83    protected TypeKindVisitor7() {
84        super(null);
85    }
86
87    /**
88     * Constructor for concrete subclasses to call; uses the argument
89     * for the default value.
90     *
91     * @param defaultValue the value to assign to {@link #DEFAULT_VALUE}
92     */
93    protected TypeKindVisitor7(R defaultValue) {
94        super(defaultValue);
95    }
96
97    /**
98     * This implementation visits a {@code UnionType} by calling
99     * {@code defaultAction}.
100     *
101     * @param t  {@inheritDoc}
102     * @param p  {@inheritDoc}
103     * @return the result of {@code defaultAction}
104     */
105    @Override
106    public R visitUnion(UnionType t, P p) {
107        return defaultAction(t, p);
108    }
109}
110