jdk8-mips64-public/langtools: src/share/classes/javax/lang/model/type/TypeVisitor.java@09f65aad4759 (annotated)

src/share/classes/javax/lang/model/type/TypeVisitor.java@09f65aad4759 (annotated)

src/share/classes/javax/lang/model/type/TypeVisitor.java

Wed, 23 Jan 2013 20:11:07 -0800

author: darcy
date: Wed, 23 Jan 2013 20:11:07 -0800
changeset 1522: 09f65aad4759
parent 1521: 71f35e4b93a5
child 1644: 40adaf938847
permissions: -rw-r--r--

8006264: Add explanation of why default methods cannot be used in JDK 8 javax.lang.model
Reviewed-by: jjg

 /*
  * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
 package javax.lang.model.type;
 import javax.lang.model.element.*;
 /**
  * A visitor of types, in the style of the
  * visitor design pattern.  Classes implementing this
  * interface are used to operate on a type when the kind of
  * type is unknown at compile time.  When a visitor is passed to a
  * type's {@link TypeMirror#accept accept} method, the <tt>visit<i>XYZ</i></tt>
  * method most applicable to that type is invoked.
  *
  * <p> Classes implementing this interface may or may not throw a
  * {@code NullPointerException} if the additional parameter {@code p}
  * is {@code null}; see documentation of the implementing class for
  * details.
  *
  * <p> <b>WARNING:</b> It is possible that methods will be added to
  * this interface to accommodate new, currently unknown, language
  * structures added to future versions of the Java&trade; programming
  * language.  Therefore, visitor classes directly implementing this
  * interface may be source incompatible with future versions of the
  * platform.  To avoid this source incompatibility, visitor
  * implementations are encouraged to instead extend the appropriate
  * abstract visitor class that implements this interface.  However, an
  * API should generally use this visitor interface as the type for
  * parameters, return type, etc. rather than one of the abstract
  * classes.
  *
  * <p>Note that methods to accommodate new language constructs could
  * be added in a source <em>compatible</em> way if they were added as
  * <em>default methods</em>.  However, default methods are only
  * available on Java SE 8 and higher releases and the {@code
  * javax.lang.model.*} packages bundled in Java SE 8 are required to
  * also be runnable on Java SE 7.  Therefore, default methods
  * <em>cannot</em> be used when extending {@code javax.lang.model.*}
  * to cover Java SE 8 language features.  However, default methods may
  * be used in subsequent revisions of the {@code javax.lang.model.*}
  * packages that are only required to run on Java SE 8 and higher
  * platform versions.
  *
  * @param <R> the return type of this visitor's methods.  Use {@link
  *            Void} for visitors that do not need to return results.
  * @param <P> the type of the additional parameter to this visitor's
  *            methods.  Use {@code Void} for visitors that do not need an
  *            additional parameter.
  *
  * @author Joseph D. Darcy
  * @author Scott Seligman
  * @author Peter von der Ah&eacute;
  * @since 1.6
  */
 public interface TypeVisitor<R, P> {
     /**
      * Visits a type.
      * @param t the type to visit
      * @param p a visitor-specified parameter
      * @return  a visitor-specified result
      */
     R visit(TypeMirror t, P p);
     /**
      * A convenience method equivalent to {@code v.visit(t, null)}.
      * @param t the element to visit
      * @return  a visitor-specified result
      */
     R visit(TypeMirror t);
     /**
      * Visits a primitive type.
      * @param t the type to visit
      * @param p a visitor-specified parameter
      * @return  a visitor-specified result
      */
     R visitPrimitive(PrimitiveType t, P p);
     /**
      * Visits the null type.
      * @param t the type to visit
      * @param p a visitor-specified parameter
      * @return  a visitor-specified result
      */
     R visitNull(NullType t, P p);
     /**
      * Visits an array type.
      * @param t the type to visit
      * @param p a visitor-specified parameter
      * @return  a visitor-specified result
      */
     R visitArray(ArrayType t, P p);
     /**
      * Visits a declared type.
      * @param t the type to visit
      * @param p a visitor-specified parameter
      * @return  a visitor-specified result
      */
     R visitDeclared(DeclaredType t, P p);
     /**
      * Visits an error type.
      * @param t the type to visit
      * @param p a visitor-specified parameter
      * @return  a visitor-specified result
      */
     R visitError(ErrorType t, P p);
     /**
      * Visits a type variable.
      * @param t the type to visit
      * @param p a visitor-specified parameter
      * @return  a visitor-specified result
      */
     R visitTypeVariable(TypeVariable t, P p);
     /**
      * Visits a wildcard type.
      * @param t the type to visit
      * @param p a visitor-specified parameter
      * @return  a visitor-specified result
      */
     R visitWildcard(WildcardType t, P p);
     /**
      * Visits an executable type.
      * @param t the type to visit
      * @param p a visitor-specified parameter
      * @return  a visitor-specified result
      */
     R visitExecutable(ExecutableType t, P p);
     /**
      * Visits a {@link NoType} instance.
      * @param t the type to visit
      * @param p a visitor-specified parameter
      * @return  a visitor-specified result
      */
     R visitNoType(NoType t, P p);
     /**
      * Visits an unknown kind of type.
      * This can occur if the language evolves and new kinds
      * of types are added to the {@code TypeMirror} hierarchy.
      * @param t the type to visit
      * @param p a visitor-specified parameter
      * @return  a visitor-specified result
      * @throws UnknownTypeException
      *  a visitor implementation may optionally throw this exception
      */
     R visitUnknown(TypeMirror t, P p);
     /**
      * Visits a union type.
      *
      * @param t the type to visit
      * @param p a visitor-specified parameter
      * @return  a visitor-specified result
      * @since 1.7
      */
     R visitUnion(UnionType t, P p);
     /**
      * Visits an intersection type.
      *
      * @param t the type to visit
      * @param p a visitor-specified parameter
      * @return  a visitor-specified result
      * @since 1.8
      */
     R visitIntersection(IntersectionType t, P p);
     /**
      * Visits an annotated type.
      *
      * @param t the type to visit
      * @param p a visitor-specified parameter
      * @return  a visitor-specified result
      * @since 1.8
      */
     R visitAnnotated(AnnotatedType t, P p);
 }

Mercurial > jdk8-mips64-public > langtools / annotate

src/share/classes/javax/lang/model/type/TypeVisitor.java@09f65aad4759 (annotated)

src/share/classes/javax/lang/model/type/TypeVisitor.java