diff -r 000000000000 -r 959103a6100f src/share/classes/javax/lang/model/util/ElementScanner6.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/classes/javax/lang/model/util/ElementScanner6.java Wed Apr 27 01:34:52 2016 +0800 @@ -0,0 +1,220 @@ +/* + * 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.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 visitXYZ 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 + * visitXYZ 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. + * + *

When a subclass overrides a visitXYZ method, the + * new method can cause the enclosed elements to be scanned in the + * default way by calling super.visitXYZ. 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 + * super.visitXYZ 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 super.visitXYZ, an overriding visit method + * should call {@code scan} with the elements in the desired order. + * + *

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. + * + *

WARNING: 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"}. + * + *

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 the return type of this visitor's methods. Use {@link + * Void} for visitors that do not need to return results. + * @param

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 + * @since 1.6 + */ +@SupportedSourceVersion(RELEASE_6) +public class ElementScanner6 extends AbstractElementVisitor6 { + /** + * The specified default value. + */ + protected final R DEFAULT_VALUE; + + /** + * Constructor for concrete subclasses; uses {@code null} for the + * default value. + */ + protected ElementScanner6(){ + DEFAULT_VALUE = null; + } + + /** + * Constructor for concrete subclasses; uses the argument for the + * default value. + * + * @param defaultValue the default value + */ + 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 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); + } +}