| /* Root.java -- The root of an object tree. |
| Copyright (C) 2005 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath 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 for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package gnu.java.beans.encoder; |
| |
| import java.beans.XMLEncoder; |
| import java.util.Iterator; |
| import java.util.Stack; |
| |
| import gnu.java.beans.encoder.elements.Element; |
| |
| /** <p><code>Root</code> provides a simple interface to a tree of |
| * objects.</p> |
| * |
| * <p>Using an instance of this class a logical representation of |
| * the real object tree that is serialized can be built. When the |
| * actual data should be written as XML <code>Root</code> and |
| * {@link gnu.java.beans.encoder.elements.Element} class can provide |
| * context information which is used to write the best fitting |
| * XML representation.</p> |
| * |
| * @author Robert Schuster (robertschuster@fsfe.org) |
| */ |
| public class Root |
| { |
| private Stack parents = new Stack(); |
| |
| private Element rootElement, current; |
| |
| private boolean started; |
| |
| public Root() |
| { |
| rootElement = current = new RootElement(); |
| } |
| |
| /** <p>Adds another child element to the tree.</p> |
| * |
| * <p>The new element automatically becomes the current |
| * element.</p> |
| * |
| * @param elem The new child element. |
| */ |
| public void addChild(Element elem) |
| { |
| current.addChild(elem); |
| |
| parents.push(current); |
| current = elem; |
| } |
| |
| /** |
| * <p>Marks that the end of the current element |
| * is reached and that no more childs are added to |
| * it.</p> |
| * |
| * <p>The behavior is to return to the nearest parent |
| * element.</p> |
| */ |
| public void end() |
| { |
| current = (Element) parents.pop(); |
| } |
| |
| /** |
| * <p>Goes back to the nearest parent element but |
| * deletes the just created child.</p> |
| * |
| * <p>This is used if something went wrong while |
| * processing the child element's {@link java.beans.Expression} |
| * or {@link java.beans.Statement}.</p> |
| * |
| */ |
| public void deleteLast() |
| { |
| current = (Element) parents.pop(); |
| |
| current.removeLast(); |
| } |
| |
| /** |
| * <p>Traverses the elements in the object tree |
| * and creates their XML representation in the output |
| * stream of the given {@link Writer}.</p> |
| * |
| * <p>Finally the <code>Writer</code> is flushed.</p> |
| * |
| * @param writer The Writer instance that generates the XML representation. |
| */ |
| public void traverse(Writer writer) |
| { |
| if (!started) |
| { |
| writer.writePreamble(); |
| rootElement.writeStart(writer); |
| } |
| started = true; |
| |
| traverse(writer, rootElement.iterator()); |
| |
| rootElement.clear(); |
| |
| writer.flush(); |
| } |
| |
| /** Writes the closing element and closes the {@link Writer} |
| * |
| * @param writer The Writer instance that generates the XML representation. |
| */ |
| public void close(Writer writer) |
| { |
| rootElement.writeEnd(writer); |
| writer.close(); |
| } |
| |
| /** Recursively traverses the object tree. |
| * |
| * @param writer The Writer instance that generates the XML representation. |
| * @param ite An Iterator returning Element instances. |
| */ |
| private void traverse(Writer writer, Iterator ite) |
| { |
| while (ite.hasNext()) |
| { |
| Element e = (Element) ite.next(); |
| e.writeStart(writer); |
| |
| traverse(writer, e.iterator()); |
| |
| e.writeEnd(writer); |
| |
| e.clear(); |
| } |
| } |
| |
| /** <p>A special Element implementation that represents the |
| * encoder's context.</p> |
| * |
| * <p>This element is written only once per Writer.</p> |
| * |
| * <p>It is assumed that this element is never empty to simplify |
| * the implementation.</p> |
| * |
| * @author Robert Schuster (robertschuster@fsfe.org); |
| * |
| */ |
| static class RootElement extends Element |
| { |
| public void writeStart(Writer writer) |
| { |
| writer.write("java", new String[] { "version", "class" }, |
| new String[] { System.getProperty("java.version"), |
| XMLEncoder.class.getName() }, false); |
| } |
| |
| public void writeEnd(Writer writer) |
| { |
| writer.writeEnd(false); |
| } |
| |
| } |
| |
| } |