AbstractElementVisitor6.java revision 3892:444b89786af3 
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
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25
26package javax.lang.model.util;
27
28import javax.annotation.processing.SupportedSourceVersion;
29import javax.lang.model.SourceVersion;
30import javax.lang.model.element.*;
31import static javax.lang.model.SourceVersion.*;
32
33
34/**
35 * A skeletal visitor of program elements with default behavior
36 * appropriate for the {@link SourceVersion#RELEASE_6 RELEASE_6}
37 * source version.
38 *
39 * <p> <b>WARNING:</b> The {@code ElementVisitor} interface
40 * implemented by this class may have methods added to it in the
41 * future to accommodate new, currently unknown, language structures
42 * added to future versions of the Java&trade; programming language.
43 * Therefore, methods whose names begin with {@code "visit"} may be
44 * added to this class in the future; to avoid incompatibilities,
45 * classes which extend this class should not declare any instance
46 * methods with names beginning with {@code "visit"}.
47 *
48 * <p>When such a new visit method is added, the default
49 * implementation in this class will be to call the {@link
50 * #visitUnknown visitUnknown} method.  A new abstract element visitor
51 * class will also be introduced to correspond to the new language
52 * level; this visitor will have different default behavior for the
53 * visit method in question.  When the new visitor is introduced, all
54 * or portions of this visitor may be deprecated.
55 *
56 * @param <R> the return type of this visitor's methods.  Use {@link
57 *            Void} for visitors that do not need to return results.
58 * @param <P> the type of the additional parameter to this visitor's
59 *            methods.  Use {@code Void} for visitors that do not need an
60 *            additional parameter.
61 *
62 * @author Joseph D. Darcy
63 * @author Scott Seligman
64 * @author Peter von der Ah&eacute;
65 *
66 * @see AbstractElementVisitor7
67 * @see AbstractElementVisitor8
68 * @see AbstractElementVisitor9
69 * @since 1.6
70 */
71@SupportedSourceVersion(RELEASE_6)
72public abstract class AbstractElementVisitor6<R, P> implements ElementVisitor<R, P> {
73    /**
74     * Constructor for concrete subclasses to call.
75     * @deprecated Release 6 is obsolete; update to a visitor for a newer
76     * release level.
77     */
78    @Deprecated
79    protected AbstractElementVisitor6(){}
80
81    /**
82     * Visits any program element as if by passing itself to that
83     * element's {@link Element#accept accept} method.  The invocation
84     * {@code v.visit(elem)} is equivalent to {@code elem.accept(v,
85     * p)}.
86     *
87     * @param e  the element to visit
88     * @param p  a visitor-specified parameter
89     * @return a visitor-specified result
90     */
91    public final R visit(Element e, P p) {
92        return e.accept(this, p);
93    }
94
95    /**
96     * Visits any program element as if by passing itself to that
97     * element's {@link Element#accept accept} method and passing
98     * {@code null} for the additional parameter.  The invocation
99     * {@code v.visit(elem)} is equivalent to {@code elem.accept(v,
100     * null)}.
101     *
102     * @param e  the element to visit
103     * @return a visitor-specified result
104     */
105    public final R visit(Element e) {
106        return e.accept(this, null);
107    }
108
109    /**
110     * {@inheritDoc}
111     *
112     * @implSpec The default implementation of this method in
113     * {@code AbstractElementVisitor6} will always throw
114     * {@code UnknownElementException}.
115     * This behavior is not required of a subclass.
116     *
117     * @param e {@inheritDoc}
118     * @param p {@inheritDoc}
119     * @return a visitor-specified result
120     * @throws UnknownElementException
121     *          a visitor implementation may optionally throw this exception
122     */
123    @Override
124    public R visitUnknown(Element e, P p) {
125        throw new UnknownElementException(e, p);
126    }
127
128    /**
129     * {@inheritDoc}
130     *
131     * @implSpec Visits a {@code ModuleElement} by calling {@code
132     * visitUnknown}.
133     *
134     * @param e  {@inheritDoc}
135     * @param p  {@inheritDoc}
136     * @return the result of {@code visitUnknown}
137     *
138     * @since 9
139     */
140    @Override
141    public R visitModule(ModuleElement e, P p) {
142        return visitUnknown(e, p);
143    }
144}
145