001: /*
002: * Copyright 2005-2006 Sun Microsystems, Inc. All Rights Reserved.
003: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004: *
005: * This code is free software; you can redistribute it and/or modify it
006: * under the terms of the GNU General Public License version 2 only, as
007: * published by the Free Software Foundation. Sun designates this
008: * particular file as subject to the "Classpath" exception as provided
009: * by Sun in the LICENSE file that accompanied this code.
010: *
011: * This code is distributed in the hope that it will be useful, but WITHOUT
012: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014: * version 2 for more details (a copy is included in the LICENSE file that
015: * accompanied this code).
016: *
017: * You should have received a copy of the GNU General Public License version
018: * 2 along with this work; if not, write to the Free Software Foundation,
019: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020: *
021: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022: * CA 95054 USA or visit www.sun.com if you need additional information or
023: * have any questions.
024: */
025:
026: package javax.lang.model.util;
027:
028: import javax.lang.model.element.*;
029: import javax.annotation.processing.SupportedSourceVersion;
030: import javax.lang.model.element.*;
031: import static javax.lang.model.element.ElementKind.*;
032: import static javax.lang.model.SourceVersion.*;
033: import javax.lang.model.SourceVersion;
034:
035: /**
036: * A skeletal visitor of program elements with default behavior
037: * appropriate for the {@link SourceVersion#RELEASE_6 RELEASE_6}
038: * source version.
039: *
040: * <p> <b>WARNING:</b> The {@code ElementVisitor} interface
041: * implemented by this class may have methods added to it in the
042: * future to accommodate new, currently unknown, language structures
043: * added to future versions of the Java™ programming language.
044: * Therefore, methods whose names begin with {@code "visit"} may be
045: * added to this class in the future; to avoid incompatibilities,
046: * classes which extend this class should not declare any instance
047: * methods with names beginning with {@code "visit"}.
048: *
049: * <p>When such a new visit method is added, the default
050: * implementation in this class will be to call the {@link
051: * #visitUnknown visitUnknown} method. A new abstract element visitor
052: * class will also be introduced to correspond to the new language
053: * level; this visitor will have different default behavior for the
054: * visit method in question. When the new visitor is introduced, all
055: * or portions of this visitor may be deprecated.
056: *
057: * @param <R> the return type of this visitor's methods. Use {@link
058: * Void} for visitors that do not need to return results.
059: * @param <P> the type of the additional parameter to this visitor's
060: * methods. Use {@code Void} for visitors that do not need an
061: * additional parameter.
062: *
063: * @author Joseph D. Darcy
064: * @author Scott Seligman
065: * @author Peter von der Ahé
066: * @version 1.10 07/05/05
067: * @since 1.6
068: */
069: @SupportedSourceVersion(RELEASE_6)
070: public abstract class AbstractElementVisitor6<R, P> implements
071: ElementVisitor<R, P> {
072: /**
073: * Constructor for concrete subclasses to call.
074: */
075: protected AbstractElementVisitor6() {
076: }
077:
078: /**
079: * Visits any program element as if by passing itself to that
080: * element's {@link Element#accept accept} method. The invocation
081: * {@code v.visit(elem)} is equivalent to {@code elem.accept(v,
082: * p)}.
083: *
084: * @param e the element to visit
085: * @param p a visitor-specified parameter
086: * @return a visitor-specified result
087: */
088: public final R visit(Element e, P p) {
089: return e.accept(this , p);
090: }
091:
092: /**
093: * Visits any program element as if by passing itself to that
094: * element's {@link Element#accept accept} method and passing
095: * {@code null} for the additional parameter. The invocation
096: * {@code v.visit(elem)} is equivalent to {@code elem.accept(v,
097: * null)}.
098: *
099: * @param e the element to visit
100: * @return a visitor-specified result
101: */
102: public final R visit(Element e) {
103: return e.accept(this , null);
104: }
105:
106: /**
107: * {@inheritDoc}
108: *
109: * <p> The default implementation of this method in
110: * {@code AbstractElementVisitor6} will always throw
111: * {@code UnknownElementException}.
112: * This behavior is not required of a subclass.
113: *
114: * @param e the element to visit
115: * @param p a visitor-specified parameter
116: * @return a visitor-specified result
117: * @throws UnknownElementException
118: * a visitor implementation may optionally throw this exception
119: */
120: public R visitUnknown(Element e, P p) {
121: throw new UnknownElementException(e, p);
122: }
123: }
|