jdk/src/java.compiler/share/classes/javax/lang/model/util/ElementScannerPreview.java
Joe Darcy 5860a48c71 8329624: Add visitors for preview language features
Reviewed-by: vromero, jlahoda
2024-04-05 05:04:48 +00:00

106 lines
4.4 KiB
Java

/*
* Copyright (c) 2019, 2024, 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.util;
import jdk.internal.javac.PreviewFeature;
import java.util.List;
import java.util.ArrayList;
import javax.annotation.processing.SupportedSourceVersion;
import javax.annotation.processing.ProcessingEnvironment;
import javax.lang.model.element.*;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.ElementVisitor;
import static javax.lang.model.SourceVersion.*;
/**
* A scanning visitor of program elements with default behavior
* appropriate for a {@linkplain
* ProcessingEnvironment#isPreviewEnabled preview} source version.
*
* The <code>visit<i>Xyz</i></code> methods in this class scan their
* component elements by calling {@link ElementScanner6#scan(Element,
* Object) scan} on their {@linkplain Element#getEnclosedElements
* enclosed elements}, {@linkplain ExecutableElement#getParameters
* parameters}, etc., as indicated in the individual method
* specifications. A subclass can control the order elements are
* visited by overriding the <code>visit<i>Xyz</i></code> methods.
* Note that clients of a scanner may get the desired behavior by
* invoking {@code v.scan(e, p)} rather than {@code v.visit(e, p)} on
* the root objects of interest.
*
* <p>When a subclass overrides a <code>visit<i>Xyz</i></code> method, the
* new method can cause the enclosed elements to be scanned in the
* default way by calling <code>super.visit<i>Xyz</i></code>. In this
* fashion, the concrete visitor can control the ordering of traversal
* over the component elements with respect to the additional
* processing; for example, consistently calling
* <code>super.visit<i>Xyz</i></code> at the start of the overridden
* methods will yield a preorder traversal, etc. If the component
* elements should be traversed in some other order, instead of
* calling <code>super.visit<i>Xyz</i></code>, an overriding visit method
* should call {@code scan} with the elements in the desired order.
*
* @apiNote
* Methods in this class may be overridden subject to their general
* contract.
*
* @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.
*
* @see <a href="ElementScanner6.html#note_for_subclasses"><strong>Compatibility note for subclasses</strong></a>
* @see ElementScanner6
* @see ElementScanner7
* @see ElementScanner8
* @see ElementScanner9
* @see ElementScanner14
* @since 23
*/
@SupportedSourceVersion(RELEASE_23)
@PreviewFeature(feature=PreviewFeature.Feature.LANGUAGE_MODEL, reflective=true)
public class ElementScannerPreview<R, P> extends ElementScanner14<R, P> {
/**
* Constructor for concrete subclasses; uses {@code null} for the
* default value.
*/
protected ElementScannerPreview(){
super(null);
}
/**
* Constructor for concrete subclasses; uses the argument for the
* default value.
*
* @param defaultValue the default value
*/
protected ElementScannerPreview(R defaultValue){
super(defaultValue);
}
}