doparse.java

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/*
 * Copyright (C) 1999-2001 David Brownell
 * 
 * This file is part of GNU JAXP, a library.
 *
 * GNU JAXP 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 of the License, or
 * (at your option) any later version.
 * 
 * GNU JAXP 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * As a special exception, if you link this library with other files to
 * produce an executable, this library does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * This exception does not however invalidate any other reasons why the
 * executable file might be covered by the GNU General Public License. 
 */

package gnu.xml.util;

import java.io.*;

import org.xml.sax.*;
import org.xml.sax.helpers.XMLReaderFactory;
import org.xml.sax.ext.*;

// import gnu.xml.pipeline.*;
// Added imports directly to fix a GCJ problem.
import gnu.xml.pipeline.CallFilter;
import gnu.xml.pipeline.DomConsumer;
import gnu.xml.pipeline.EventConsumer;
import gnu.xml.pipeline.EventFilter;
import gnu.xml.pipeline.LinkFilter;
import gnu.xml.pipeline.NSFilter;
import gnu.xml.pipeline.PipelineFactory;
import gnu.xml.pipeline.TeeConsumer;
import gnu.xml.pipeline.TextConsumer;
import gnu.xml.pipeline.ValidationConsumer;
import gnu.xml.pipeline.WellFormednessFilter;
import gnu.xml.pipeline.XIncludeFilter;
import gnu.xml.pipeline.XsltFilter;


/**
 * This class provides a driver which may be invoked from the command line
 * to process a document using a SAX2 parser and a specified XML processing
 * pipeline.
 * This facilitates some common types of command line tools, such as parsing an
 * XML document in order test it for well formedness or validity.
 *
 * <p>The SAX2 XMLReaderFactory should return a SAX2 XML parser which
 * supports both of the standardized extension handlers (for declaration
 * and lexical events).  That parser will be used to produce events.
 *
 * <p>The first parameter to the command gives the name of the document that
 * will be given to that processor.  If it is a file name, it is converted
 * to a URL first.
 *
 * <p>The second parameter describes a simple processing pipeline, and will
 * be used as input to {@link gnu.xml.pipeline.PipelineFactory}
 * methods which identify the processing to be done.  Examples of such a
 * pipeline include <pre>
 *
 *    nsfix | validate                <em>to validate the input document </em>
 *    nsfix | write ( stdout )        <em>to echo the file as XML text</em>
 *    dom | nsfix | write ( stdout )  <em>parse into DOM, print the result</em>
 * </pre>
 *
 * <p> Relatively complex pipelines can be described on the command line, but
 * not all interesting ones will require as little configuration as can be done
 * in that way.  Put filters like "nsfix", perhaps followed by "validate",
 * at the front of the pipeline so they can be optimized out if a parser
 * supports those modes natively.
 *
 * <p> If the parsing is aborted for any reason, the JVM will exit with a
 * failure code.  If a validating parse was done then both validation and
 * well formedness errors will cause a failure.  A non-validating parse
 * will report failure on well formedness errors.
 *
 * @see gnu.xml.pipeline.PipelineFactory
 *
 * @author David Brownell
 */
final public class DoParse
{
    private DoParse () { /* no instances allowed */ }

    // first reported nonrecoverable error
    private static SAXParseException	fatal;

    // error categories
    private static int			errorCount;
    private static int			fatalCount;

    /**
     * Command line invoker for this class; pass a filename or URL
     * as the first argument, and a pipeline description as the second.
     * Make sure to use filters to condition the input to stages that
     * require it; an <em>nsfix</em> filter will be a common requirement,
     * to restore syntax that SAX2 parsers delete by default.  Some
     * conditioning filters may be eliminated by setting parser options.
     * (For example, "nsfix" can set the "namespace-prefixes" feature to
     * a non-default value of "true".  In the same way, "validate" can set
     * the "validation" feature to "true".)
     */
    public static void main (String argv [])
    throws IOException
    {
	int		exitStatus = 1;

	if (argv.length != 2) {
	    System.err.println ("Usage: DoParse [filename|URL] pipeline-spec");
	    System.err.println ("Example pipeline specs:");
	    System.err.println ("  'nsfix | validate'");
	    System.err.println (
		"       ... restore namespace syntax, validate");
	    System.err.println ("  'nsfix | write ( stdout )'");
	    System.err.println (
		"       ... restore namespace syntax, write to stdout as XML"
		);
	    System.exit (1);
	}

	try {
	    //
	    // Get input source for specified document (or try ;-)
	    //
	    argv [0] = Resolver.getURL (argv [0]);
	    InputSource input = new InputSource (argv [0]);

	    //
	    // Get the producer, using the system default parser (which
	    // can be overridden for this particular invocation).
	    //
	    // And the pipeline, using commandline options.
	    //
	    XMLReader		producer;
	    EventConsumer	consumer;

	    producer = XMLReaderFactory.createXMLReader ();

	    //
	    // XXX pipeline factory now has a pre-tokenized input
	    // method, use it ... that way at least some params
	    // can be written using quotes (have spaces, ...)
	    //
	    consumer = PipelineFactory.createPipeline (argv [1]);

	    //
	    // XXX want commandline option for tweaking error handler.
	    // Want to be able to present warnings.
	    //
	    producer.setErrorHandler (new MyErrorHandler ());

	    // XXX need facility enabling resolving to local DTDs

	    //
	    // Parse.  The pipeline may get optimized a bit, so we
	    // can't always fail cleanly for validation without taking
	    // a look at the filter stages.
	    //
	    EventFilter.bind (producer, consumer);
	    producer.parse (input);

	    try {
		if (producer.getFeature (
			"http://org.xml/sax/features/validation"))
		    exitStatus = ((errorCount + fatalCount) > 0) ? 1 : 0;
		else if (fatalCount == 0)
		    exitStatus = 0;
	    } catch (SAXException e) {
		if (hasValidator (consumer))
		    exitStatus = ((errorCount + fatalCount) > 0) ? 1 : 0;
		else if (fatalCount == 0)
		    exitStatus = 0;
	    }

	} catch (java.net.MalformedURLException e) {
	    System.err.println ("** Malformed URL: " + e.getMessage ());
	    System.err.println ("Is '" + argv [0] + "' a non-existent file?");
	    e.printStackTrace ();
		// e.g. FNF

	} catch (SAXParseException e) {
	    if (e != fatal) {
		System.err.print (printParseException ("Parsing Aborted", e));
		e.printStackTrace ();
		if (e.getException () != null) {
		    System.err.println ("++ Wrapped exception:");
		    e.getException ().printStackTrace ();
		}
	    }

	} catch (SAXException e) {
	    Exception	x = e;
	    if (e.getException () != null)
		x = e.getException ();
	    x.printStackTrace ();

	} catch (Throwable t) {
	    t.printStackTrace ();
	}

	System.exit (exitStatus);
    }

    // returns true if saw a validator (before end or unrecognized node)
    // false otherwise
    private static boolean hasValidator (EventConsumer e)
    {
	if (e == null)
	    return false;
	if (e instanceof ValidationConsumer)
	    return true;
	if (e instanceof TeeConsumer) {
	    TeeConsumer	t = (TeeConsumer) e;
	    return hasValidator (t.getFirst ())
		|| hasValidator (t.getRest ());
	}
	if (e instanceof WellFormednessFilter
		|| e instanceof NSFilter
		)
	    return hasValidator (((EventFilter)e).getNext ());
	
	// else ... gee, we can't know.  Assume not.

	return false;
    }

    static class MyErrorHandler implements ErrorHandler
    {
	// dump validation errors, but continue
	public void error (SAXParseException e)
	throws SAXParseException
	{
	    errorCount++;
	    System.err.print (printParseException ("Error", e));
	}

	public void warning (SAXParseException e)
	throws SAXParseException
	{
	    // System.err.print (printParseException ("Warning", e));
	}

	// try to continue fatal errors, in case a parser reports more
	public void fatalError (SAXParseException e)
	throws SAXParseException
	{
	    fatalCount++;
	    if (fatal == null)
		fatal = e;
	    System.err.print (printParseException ("Nonrecoverable Error", e));
	}
    }

    static private String printParseException (
	String			label,
	SAXParseException	e
    ) {
	StringBuffer	buf = new StringBuffer ();
	int		temp;

	buf.append ("** ");
	buf.append (label);
	buf.append (": ");
	buf.append (e.getMessage ());
	buf.append ('\n');
	if (e.getSystemId () != null) {
	    buf.append ("   URI:  ");
	    buf.append (e.getSystemId ());
	    buf.append ('\n');
	}
	if ((temp = e.getLineNumber ()) != -1) {
	    buf.append ("   line: ");
	    buf.append (temp);
	    buf.append ('\n');
	}
	if ((temp = e.getColumnNumber ()) != -1) {
	    buf.append ("   char: ");
	    buf.append (temp);
	    buf.append ('\n');
	}

	return buf.toString ();
    }
}