duke@1: /* jjg@1521: * Copyright (c) 2005, 2013, 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.type; duke@1: duke@1: import javax.lang.model.element.*; duke@1: duke@1: /** duke@1: * A visitor of types, in the style of the duke@1: * visitor design pattern. Classes implementing this duke@1: * interface are used to operate on a type when the kind of duke@1: * type is unknown at compile time. When a visitor is passed to a duke@1: * type's {@link TypeMirror#accept accept} method, the visitXYZ duke@1: * method most applicable to that type 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: * darcy@1522: *

Note that methods to accommodate new language constructs could darcy@1522: * be added in a source compatible way if they were added as darcy@1522: * default methods. However, default methods are only darcy@1522: * available on Java SE 8 and higher releases and the {@code darcy@1522: * javax.lang.model.*} packages bundled in Java SE 8 are required to darcy@1522: * also be runnable on Java SE 7. Therefore, default methods darcy@1522: * cannot be used when extending {@code javax.lang.model.*} darcy@1522: * to cover Java SE 8 language features. However, default methods may darcy@1522: * be used in subsequent revisions of the {@code javax.lang.model.*} darcy@1522: * packages that are only required to run on Java SE 8 and higher darcy@1522: * platform versions. darcy@1522: * 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: * @since 1.6 duke@1: */ duke@1: public interface TypeVisitor { duke@1: /** duke@1: * Visits a type. duke@1: * @param t the type to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visit(TypeMirror t, P p); duke@1: duke@1: /** duke@1: * A convenience method equivalent to {@code v.visit(t, null)}. duke@1: * @param t the element to visit duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visit(TypeMirror t); duke@1: duke@1: /** duke@1: * Visits a primitive type. duke@1: * @param t the type to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visitPrimitive(PrimitiveType t, P p); duke@1: duke@1: /** duke@1: * Visits the null type. duke@1: * @param t the type to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visitNull(NullType t, P p); duke@1: duke@1: /** duke@1: * Visits an array type. duke@1: * @param t the type to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visitArray(ArrayType t, P p); duke@1: duke@1: /** duke@1: * Visits a declared type. duke@1: * @param t the type to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visitDeclared(DeclaredType t, P p); duke@1: duke@1: /** duke@1: * Visits an error type. duke@1: * @param t the type to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visitError(ErrorType t, P p); duke@1: duke@1: /** duke@1: * Visits a type variable. duke@1: * @param t the type to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visitTypeVariable(TypeVariable t, P p); duke@1: duke@1: /** duke@1: * Visits a wildcard type. duke@1: * @param t the type to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visitWildcard(WildcardType t, P p); duke@1: duke@1: /** duke@1: * Visits an executable type. duke@1: * @param t the type to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visitExecutable(ExecutableType t, P p); duke@1: duke@1: /** duke@1: * Visits a {@link NoType} instance. duke@1: * @param t the type to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: */ duke@1: R visitNoType(NoType t, P p); duke@1: duke@1: /** duke@1: * Visits an unknown kind of type. duke@1: * This can occur if the language evolves and new kinds duke@1: * of types are added to the {@code TypeMirror} hierarchy. duke@1: * @param t the type to visit duke@1: * @param p a visitor-specified parameter duke@1: * @return a visitor-specified result duke@1: * @throws UnknownTypeException duke@1: * a visitor implementation may optionally throw this exception duke@1: */ duke@1: R visitUnknown(TypeMirror t, P p); darcy@851: darcy@851: /** darcy@969: * Visits a union type. darcy@851: * darcy@851: * @param t the type to visit darcy@851: * @param p a visitor-specified parameter darcy@851: * @return a visitor-specified result darcy@851: * @since 1.7 darcy@851: */ darcy@969: R visitUnion(UnionType t, P p); mcimadamore@1436: mcimadamore@1436: /** mcimadamore@1436: * Visits an intersection type. mcimadamore@1436: * mcimadamore@1436: * @param t the type to visit mcimadamore@1436: * @param p a visitor-specified parameter mcimadamore@1436: * @return a visitor-specified result mcimadamore@1436: * @since 1.8 mcimadamore@1436: */ mcimadamore@1436: R visitIntersection(IntersectionType t, P p); jjg@1521: jjg@1521: /** jjg@1521: * Visits an annotated type. jjg@1521: * jjg@1521: * @param t the type to visit jjg@1521: * @param p a visitor-specified parameter jjg@1521: * @return a visitor-specified result jjg@1521: * @since 1.8 jjg@1521: */ jjg@1521: R visitAnnotated(AnnotatedType t, P p); duke@1: }