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.type.*;
029:
030: /**
031: * A skeletal visitor of types with default behavior appropriate for
032: * the version 6 language level.
033: *
034: * <p> <b>WARNING:</b> The {@code TypeVisitor} interface implemented
035: * by this class may have methods added to it in the future to
036: * accommodate new, currently unknown, language structures added to
037: * future versions of the Java™ programming language.
038: * Therefore, methods whose names begin with {@code "visit"} may be
039: * added to this class in the future; to avoid incompatibilities,
040: * classes which extend this class should not declare any instance
041: * methods with names beginning with {@code "visit"}.
042: *
043: * <p>When such a new visit method is added, the default
044: * implementation in this class will be to call the {@link
045: * #visitUnknown visitUnknown} method. A new abstract type visitor
046: * class will also be introduced to correspond to the new language
047: * level; this visitor will have different default behavior for the
048: * visit method in question. When the new visitor is introduced, all
049: * or portions of this visitor may be deprecated.
050: *
051: * @param <R> the return type of this visitor's methods. Use {@link
052: * Void} for visitors that do not need to return results.
053: * @param <P> the type of the additional parameter to this visitor's
054: * methods. Use {@code Void} for visitors that do not need an
055: * additional parameter.
056: *
057: * @author Joseph D. Darcy
058: * @author Scott Seligman
059: * @author Peter von der Ahé
060: * @version 1.10 07/05/05
061: * @since 1.6
062: */
063: public abstract class AbstractTypeVisitor6<R, P> implements
064: TypeVisitor<R, P> {
065: /**
066: * Constructor for concrete subclasses to call.
067: */
068: protected AbstractTypeVisitor6() {
069: }
070:
071: /**
072: * Visits any type mirror as if by passing itself to that type
073: * mirror's {@link TypeMirror#accept accept} method. The
074: * invocation {@code v.visit(t, p)} is equivalent to {@code
075: * t.accept(v, p)}.
076: *
077: * @param t the type to visit
078: * @param p a visitor-specified parameter
079: * @return a visitor-specified result
080: */
081: public final R visit(TypeMirror t, P p) {
082: return t.accept(this , p);
083: }
084:
085: /**
086: * Visits any type mirror as if by passing itself to that type
087: * mirror's {@link TypeMirror#accept accept} method and passing
088: * {@code null} for the additional parameter. The invocation
089: * {@code v.visit(t)} is equivalent to {@code t.accept(v, null)}.
090: *
091: * @param t the type to visit
092: * @return a visitor-specified result
093: */
094: public final R visit(TypeMirror t) {
095: return t.accept(this , null);
096: }
097:
098: /**
099: * {@inheritDoc}
100: *
101: * <p> The default implementation of this method in {@code
102: * AbstractTypeVisitor6} will always throw {@code
103: * UnknownTypeException}. This behavior is not required of a
104: * subclass.
105: *
106: * @param t the type to visit
107: * @return a visitor-specified result
108: * @throws UnknownTypeException
109: * a visitor implementation may optionally throw this exception
110: */
111: public R visitUnknown(TypeMirror t, P p) {
112: throw new UnknownTypeException(t, p);
113: }
114: }
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