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: }