duke@1: /* ohair@798: * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. duke@1: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. duke@1: * duke@1: * This code is free software; you can redistribute it and/or modify it duke@1: * under the terms of the GNU General Public License version 2 only, as ohair@554: * published by the Free Software Foundation. Oracle designates this duke@1: * particular file as subject to the "Classpath" exception as provided ohair@554: * by Oracle in the LICENSE file that accompanied this code. duke@1: * duke@1: * This code is distributed in the hope that it will be useful, but WITHOUT duke@1: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or duke@1: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License duke@1: * version 2 for more details (a copy is included in the LICENSE file that duke@1: * accompanied this code). duke@1: * duke@1: * You should have received a copy of the GNU General Public License version duke@1: * 2 along with this work; if not, write to the Free Software Foundation, duke@1: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. duke@1: * ohair@554: * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA ohair@554: * or visit www.oracle.com if you need additional information or have any ohair@554: * questions. duke@1: */ duke@1: duke@1: package javax.lang.model.element; duke@1: duke@1: import javax.lang.model.util.*; duke@1: duke@1: /** duke@1: * A visitor of program elements, in the style of the visitor design duke@1: * pattern. Classes implementing this interface are used to operate duke@1: * on an element when the kind of element is unknown at compile time. duke@1: * When a visitor is passed to an element's {@link Element#accept duke@1: * accept} method, the visitXYZ method most applicable duke@1: * to that element is invoked. duke@1: * duke@1: *

Classes implementing this interface may or may not throw a duke@1: * {@code NullPointerException} if the additional parameter {@code p} duke@1: * is {@code null}; see documentation of the implementing class for duke@1: * details. duke@1: * duke@1: *

WARNING: It is possible that methods will be added to duke@1: * this interface to accommodate new, currently unknown, language duke@1: * structures added to future versions of the Java™ programming duke@1: * language. Therefore, visitor classes directly implementing this duke@1: * interface may be source incompatible with future versions of the duke@1: * platform. To avoid this source incompatibility, visitor duke@1: * implementations are encouraged to instead extend the appropriate duke@1: * abstract visitor class that implements this interface. However, an duke@1: * API should generally use this visitor interface as the type for duke@1: * parameters, return type, etc. rather than one of the abstract duke@1: * classes. duke@1: * duke@1: * @param the return type of this visitor's methods. Use {@link duke@1: * Void} for visitors that do not need to return results. duke@1: * @param

the type of the additional parameter to this visitor's duke@1: * methods. Use {@code Void} for visitors that do not need an duke@1: * additional parameter. duke@1: * duke@1: * @author Joseph D. Darcy duke@1: * @author Scott Seligman duke@1: * @author Peter von der Ahé duke@1: * @see AbstractElementVisitor6 darcy@575: * @see AbstractElementVisitor7 duke@1: * @since 1.6 duke@1: */ duke@1: public interface ElementVisitor { duke@1: /** duke@1: * Visits an element. duke@1: * @param e the element to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visit(Element e, P p); duke@1: duke@1: /** duke@1: * A convenience method equivalent to {@code v.visit(e, null)}. duke@1: * @param e the element to visit duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visit(Element e); duke@1: duke@1: /** duke@1: * Visits a package element. duke@1: * @param e the element to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visitPackage(PackageElement e, P p); duke@1: duke@1: /** duke@1: * Visits a type element. duke@1: * @param e the element to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visitType(TypeElement e, P p); duke@1: duke@1: /** duke@1: * Visits a variable element. duke@1: * @param e the element to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visitVariable(VariableElement e, P p); duke@1: duke@1: /** duke@1: * Visits an executable element. duke@1: * @param e the element to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visitExecutable(ExecutableElement e, P p); duke@1: duke@1: /** duke@1: * Visits a type parameter element. duke@1: * @param e the element to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visitTypeParameter(TypeParameterElement e, P p); duke@1: duke@1: /** duke@1: * Visits an unknown kind of element. duke@1: * This can occur if the language evolves and new kinds duke@1: * of elements are added to the {@code Element} hierarchy. duke@1: * duke@1: * @param e the element to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: * @throws UnknownElementException duke@1: * a visitor implementation may optionally throw this exception duke@1: */ duke@1: R visitUnknown(Element e, P p); duke@1: }