langtools/src/java.compiler/share/classes/javax/lang/model/util/ElementScanner6.java
changeset 25874 83c19f00452c
parent 25690 b1dac768ab79
child 43133 08a858022ea6
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/src/java.compiler/share/classes/javax/lang/model/util/ElementScanner6.java	Sun Aug 17 15:52:32 2014 +0100
@@ -0,0 +1,224 @@
+/*
+ * Copyright (c) 2005, 2014, 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 <tt>visit<i>XYZ</i></tt> 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
+ * <tt>visit<i>XYZ</i></tt> 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 <tt>visit<i>XYZ</i></tt> method, the
+ * new method can cause the enclosed elements to be scanned in the
+ * default way by calling <tt>super.visit<i>XYZ</i></tt>.  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
+ * <tt>super.visit<i>XYZ</i></tt> 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 <tt>super.visit<i>XYZ</i></tt>, 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&trade; 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 Ah&eacute;
+ *
+ * @see ElementScanner7
+ * @see ElementScanner8
+ * @see ElementScanner9
+ * @since 1.6
+ * @deprecated Release 6 is obsolete; update to a visitor for a newer
+ * release level.
+ */
+@Deprecated
+@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.
+     */
+    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<? 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);
+    }
+}