| /* |
| * Copyright (c) 2005, 2017, 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 javax.lang.model.element.*; |
| import javax.annotation.processing.SupportedSourceVersion; |
| import javax.lang.model.SourceVersion; |
| import static javax.lang.model.SourceVersion.*; |
| |
| |
| /** |
| * A scanning visitor of program elements with default behavior |
| * appropriate for the {@link SourceVersion#RELEASE_6 RELEASE_6} |
| * source version. The <code>visit<i>Xyz</i></code> methods in this |
| * class scan their component elements by calling {@code 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 be 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. |
| * |
| * <p> Methods in this class may be overridden subject to their |
| * general contract. Note that annotating methods in concrete |
| * subclasses with {@link java.lang.Override @Override} will help |
| * ensure that methods are overridden as intended. |
| * |
| * <p> <b>WARNING:</b> The {@code ElementVisitor} interface |
| * implemented by this class may have methods added to it in the |
| * future to accommodate new, currently unknown, language structures |
| * added to future versions of the Java™ programming language. |
| * Therefore, methods whose names begin with {@code "visit"} may be |
| * added to this class in the future; to avoid incompatibilities, |
| * classes which extend this class should not declare any instance |
| * methods with names beginning with {@code "visit"}. |
| * |
| * <p>When such a new visit method is added, the default |
| * implementation in this class will be to call the {@link |
| * #visitUnknown visitUnknown} method. A new element scanner visitor |
| * class will also be introduced to correspond to the new language |
| * level; this visitor will have different default behavior for the |
| * visit method in question. When the new visitor is introduced, all |
| * or portions of this visitor may be deprecated. |
| * |
| * @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 Ahé |
| * |
| * @see ElementScanner7 |
| * @see ElementScanner8 |
| * @see ElementScanner9 |
| * @since 1.6 |
| */ |
| @SupportedSourceVersion(RELEASE_6) |
| public class ElementScanner6<R, P> extends AbstractElementVisitor6<R, P> { |
| /** |
| * The specified default value. |
| */ |
| protected final R DEFAULT_VALUE; |
| |
| /** |
| * Constructor for concrete subclasses; uses {@code null} for the |
| * default value. |
| * @deprecated Release 6 is obsolete; update to a visitor for a newer |
| * release level. |
| */ |
| @Deprecated |
| protected ElementScanner6(){ |
| DEFAULT_VALUE = null; |
| } |
| |
| /** |
| * Constructor for concrete subclasses; uses the argument for the |
| * default value. |
| * |
| * @param defaultValue the default value |
| * @deprecated Release 6 is obsolete; update to a visitor for a newer |
| * release level. |
| */ |
| @Deprecated |
| protected ElementScanner6(R defaultValue){ |
| DEFAULT_VALUE = defaultValue; |
| } |
| |
| /** |
| * Iterates over the given elements and calls {@link |
| * #scan(Element, Object) scan(Element, P)} on each one. Returns |
| * the result of the last call to {@code scan} or {@code |
| * DEFAULT_VALUE} for an empty iterable. |
| * |
| * @param iterable the elements to scan |
| * @param p additional parameter |
| * @return the scan of the last element or {@code DEFAULT_VALUE} if no elements |
| */ |
| public final R scan(Iterable<? extends Element> iterable, P p) { |
| R result = DEFAULT_VALUE; |
| for(Element e : iterable) |
| result = scan(e, p); |
| return result; |
| } |
| |
| /** |
| * Processes an element by calling {@code e.accept(this, p)}; |
| * this method may be overridden by subclasses. |
| * |
| * @param e the element to scan |
| * @param p a scanner-specified parameter |
| * @return the result of visiting {@code e}. |
| */ |
| public R scan(Element e, P p) { |
| return e.accept(this, p); |
| } |
| |
| /** |
| * Convenience method equivalent to {@code v.scan(e, null)}. |
| * |
| * @param e the element to scan |
| * @return the result of scanning {@code e}. |
| */ |
| public final R scan(Element e) { |
| return scan(e, null); |
| } |
| |
| /** |
| * {@inheritDoc} This implementation scans the enclosed elements. |
| * |
| * @param e {@inheritDoc} |
| * @param p {@inheritDoc} |
| * @return the result of scanning |
| */ |
| public R visitPackage(PackageElement e, P p) { |
| return scan(e.getEnclosedElements(), p); |
| } |
| |
| /** |
| * {@inheritDoc} This implementation scans the enclosed elements. |
| * |
| * @param e {@inheritDoc} |
| * @param p {@inheritDoc} |
| * @return the result of scanning |
| */ |
| public R visitType(TypeElement e, P p) { |
| return scan(e.getEnclosedElements(), p); |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * This implementation scans the enclosed elements, unless the |
| * element is a {@code RESOURCE_VARIABLE} in which case {@code |
| * visitUnknown} is called. |
| * |
| * @param e {@inheritDoc} |
| * @param p {@inheritDoc} |
| * @return the result of scanning |
| */ |
| public R visitVariable(VariableElement e, P p) { |
| if (e.getKind() != ElementKind.RESOURCE_VARIABLE) |
| return scan(e.getEnclosedElements(), p); |
| else |
| return visitUnknown(e, p); |
| } |
| |
| /** |
| * {@inheritDoc} This implementation scans the parameters. |
| * |
| * @param e {@inheritDoc} |
| * @param p {@inheritDoc} |
| * @return the result of scanning |
| */ |
| public R visitExecutable(ExecutableElement e, P p) { |
| return scan(e.getParameters(), p); |
| } |
| |
| /** |
| * {@inheritDoc} This implementation scans the enclosed elements. |
| * |
| * @param e {@inheritDoc} |
| * @param p {@inheritDoc} |
| * @return the result of scanning |
| */ |
| public R visitTypeParameter(TypeParameterElement e, P p) { |
| return scan(e.getEnclosedElements(), p); |
| } |
| } |