mirror of git://gcc.gnu.org/git/gcc.git
418 lines
12 KiB
Java
418 lines
12 KiB
Java
/* TeeConsumer.java --
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Copyright (C) 1999,2000,2001 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package gnu.xml.pipeline;
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import org.xml.sax.Attributes;
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import org.xml.sax.ContentHandler;
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import org.xml.sax.DTDHandler;
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import org.xml.sax.ErrorHandler;
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import org.xml.sax.Locator;
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import org.xml.sax.SAXException;
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import org.xml.sax.SAXNotRecognizedException;
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import org.xml.sax.ext.DeclHandler;
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import org.xml.sax.ext.LexicalHandler;
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/**
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* Fans its events out to two other consumers, a "tee" filter stage in an
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* event pipeline. Networks can be assembled with multiple output points.
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*
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* <p> Error handling should be simple if you remember that exceptions
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* you throw will cancel later stages in that callback's pipeline, and
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* generally the producer will stop if it sees such an exception. You
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* may want to protect your pipeline against such backflows, making a
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* kind of reverse filter (or valve?) so that certain exceptions thrown by
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* your pipeline will caught and handled before the producer sees them.
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* Just use a "try/catch" block, rememebering that really important
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* cleanup tasks should be in "finally" clauses.
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*
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* <p> That issue isn't unique to "tee" consumers, but tee consumers have
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* the additional twist that exceptions thrown by the first consumer
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* will cause the second consumer not to see the callback (except for
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* the endDocument callback, which signals state cleanup).
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*
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* @author David Brownell
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*/
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final public class TeeConsumer
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implements EventConsumer,
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ContentHandler, DTDHandler,
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LexicalHandler,DeclHandler
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{
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private EventConsumer first, rest;
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// cached to minimize time overhead
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private ContentHandler docFirst, docRest;
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private DeclHandler declFirst, declRest;
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private LexicalHandler lexFirst, lexRest;
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/**
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* Constructs a consumer which sends all its events to the first
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* consumer, and then the second one. If the first consumer throws
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* an exception, the second one will not see the event which
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* caused that exception to be reported.
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*
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* @param car The first consumer to get the events
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* @param cdr The second consumer to get the events
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*/
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public TeeConsumer (EventConsumer car, EventConsumer cdr)
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{
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if (car == null || cdr == null)
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throw new NullPointerException ();
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first = car;
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rest = cdr;
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//
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// Cache the handlers.
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//
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docFirst = first.getContentHandler ();
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docRest = rest.getContentHandler ();
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// DTD handler isn't cached (rarely needed)
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try {
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declFirst = null;
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declFirst = (DeclHandler) first.getProperty (
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EventFilter.DECL_HANDLER);
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} catch (SAXException e) {}
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try {
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declRest = null;
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declRest = (DeclHandler) rest.getProperty (
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EventFilter.DECL_HANDLER);
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} catch (SAXException e) {}
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try {
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lexFirst = null;
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lexFirst = (LexicalHandler) first.getProperty (
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EventFilter.LEXICAL_HANDLER);
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} catch (SAXException e) {}
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try {
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lexRest = null;
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lexRest = (LexicalHandler) rest.getProperty (
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EventFilter.LEXICAL_HANDLER);
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} catch (SAXException e) {}
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}
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/* FIXME
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/**
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* Constructs a pipeline, and is otherwise a shorthand for the
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* two-consumer constructor for this class.
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*
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* @param first Description of the first pipeline to get events,
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* which will be passed to {@link PipelineFactory#createPipeline}
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* @param rest The second pipeline to get the events
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* /
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// constructor used by PipelineFactory
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public TeeConsumer (String first, EventConsumer rest)
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throws IOException
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{
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this (PipelineFactory.createPipeline (first), rest);
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}
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*/
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/** Returns the first pipeline to get event calls. */
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public EventConsumer getFirst ()
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{ return first; }
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/** Returns the second pipeline to get event calls. */
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public EventConsumer getRest ()
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{ return rest; }
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/** Returns the content handler being used. */
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final public ContentHandler getContentHandler ()
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{
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if (docRest == null)
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return docFirst;
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if (docFirst == null)
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return docRest;
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return this;
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}
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/** Returns the dtd handler being used. */
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final public DTDHandler getDTDHandler ()
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{
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// not cached (hardly used)
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if (rest.getDTDHandler () == null)
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return first.getDTDHandler ();
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if (first.getDTDHandler () == null)
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return rest.getDTDHandler ();
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return this;
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}
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/** Returns the declaration or lexical handler being used. */
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final public Object getProperty (String id)
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throws SAXNotRecognizedException
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{
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//
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// in degenerate cases, we have no work to do.
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//
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Object firstProp = null, restProp = null;
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try { firstProp = first.getProperty (id); }
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catch (SAXNotRecognizedException e) { /* ignore */ }
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try { restProp = rest.getProperty (id); }
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catch (SAXNotRecognizedException e) { /* ignore */ }
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if (restProp == null)
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return firstProp;
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if (firstProp == null)
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return restProp;
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//
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// we've got work to do; handle two builtin cases.
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//
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if (EventFilter.DECL_HANDLER.equals (id))
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return this;
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if (EventFilter.LEXICAL_HANDLER.equals (id))
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return this;
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//
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// non-degenerate, handled by both consumers, but we don't know
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// how to handle this.
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//
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throw new SAXNotRecognizedException ("can't tee: " + id);
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}
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/**
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* Provides the error handler to both subsequent nodes of
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* this filter stage.
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*/
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public void setErrorHandler (ErrorHandler handler)
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{
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first.setErrorHandler (handler);
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rest.setErrorHandler (handler);
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}
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//
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// ContentHandler
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//
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public void setDocumentLocator (Locator locator)
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{
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// this call is not made by all parsers
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docFirst.setDocumentLocator (locator);
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docRest.setDocumentLocator (locator);
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}
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public void startDocument ()
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throws SAXException
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{
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docFirst.startDocument ();
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docRest.startDocument ();
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}
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public void endDocument ()
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throws SAXException
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{
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try {
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docFirst.endDocument ();
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} finally {
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docRest.endDocument ();
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}
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}
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public void startPrefixMapping (String prefix, String uri)
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throws SAXException
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{
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docFirst.startPrefixMapping (prefix, uri);
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docRest.startPrefixMapping (prefix, uri);
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}
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public void endPrefixMapping (String prefix)
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throws SAXException
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{
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docFirst.endPrefixMapping (prefix);
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docRest.endPrefixMapping (prefix);
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}
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public void skippedEntity (String name)
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throws SAXException
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{
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docFirst.skippedEntity (name);
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docRest.skippedEntity (name);
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}
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public void startElement (String uri, String localName,
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String qName, Attributes atts)
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throws SAXException
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{
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docFirst.startElement (uri, localName, qName, atts);
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docRest.startElement (uri, localName, qName, atts);
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}
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public void endElement (String uri, String localName, String qName)
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throws SAXException
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{
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docFirst.endElement (uri, localName, qName);
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docRest.endElement (uri, localName, qName);
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}
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public void processingInstruction (String target, String data)
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throws SAXException
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{
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docFirst.processingInstruction (target, data);
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docRest.processingInstruction (target, data);
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}
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public void characters (char ch [], int start, int length)
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throws SAXException
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{
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docFirst.characters (ch, start, length);
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docRest.characters (ch, start, length);
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}
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public void ignorableWhitespace (char ch [], int start, int length)
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throws SAXException
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{
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docFirst.ignorableWhitespace (ch, start, length);
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docRest.ignorableWhitespace (ch, start, length);
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}
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//
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// DTDHandler
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//
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public void notationDecl (String name, String publicId, String systemId)
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throws SAXException
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{
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DTDHandler l1 = first.getDTDHandler ();
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DTDHandler l2 = rest.getDTDHandler ();
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l1.notationDecl (name, publicId, systemId);
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l2.notationDecl (name, publicId, systemId);
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}
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public void unparsedEntityDecl (String name,
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String publicId, String systemId,
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String notationName
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) throws SAXException
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{
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DTDHandler l1 = first.getDTDHandler ();
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DTDHandler l2 = rest.getDTDHandler ();
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l1.unparsedEntityDecl (name, publicId, systemId, notationName);
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l2.unparsedEntityDecl (name, publicId, systemId, notationName);
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}
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//
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// DeclHandler
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//
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public void attributeDecl (String eName, String aName,
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String type,
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String mode, String value)
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throws SAXException
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{
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declFirst.attributeDecl (eName, aName, type, mode, value);
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declRest.attributeDecl (eName, aName, type, mode, value);
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}
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public void elementDecl (String name, String model)
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throws SAXException
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{
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declFirst.elementDecl (name, model);
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declRest.elementDecl (name, model);
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}
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public void externalEntityDecl (String name,
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String publicId, String systemId)
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throws SAXException
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{
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declFirst.externalEntityDecl (name, publicId, systemId);
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declRest.externalEntityDecl (name, publicId, systemId);
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}
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public void internalEntityDecl (String name, String value)
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throws SAXException
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{
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declFirst.internalEntityDecl (name, value);
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declRest.internalEntityDecl (name, value);
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}
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//
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// LexicalHandler
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//
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public void comment (char ch [], int start, int length)
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throws SAXException
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{
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lexFirst.comment (ch, start, length);
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lexRest.comment (ch, start, length);
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}
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public void startCDATA ()
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throws SAXException
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{
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lexFirst.startCDATA ();
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lexRest.startCDATA ();
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}
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public void endCDATA ()
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throws SAXException
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{
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lexFirst.endCDATA ();
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lexRest.endCDATA ();
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}
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public void startEntity (String name)
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throws SAXException
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{
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lexFirst.startEntity (name);
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lexRest.startEntity (name);
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}
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public void endEntity (String name)
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throws SAXException
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{
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lexFirst.endEntity (name);
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lexRest.endEntity (name);
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}
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public void startDTD (String name, String publicId, String systemId)
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throws SAXException
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{
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lexFirst.startDTD (name, publicId, systemId);
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lexRest.startDTD (name, publicId, systemId);
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}
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public void endDTD ()
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throws SAXException
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{
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lexFirst.endDTD ();
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lexRest.endDTD ();
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}
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}
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