source: other-projects/rsyntax-textarea/src/java/org/fife/ui/rsyntaxtextarea/parser/XmlParser.java@ 25584

/*
 * 08/16/2008
 *
 * XMLParser.java - Simple XML parser.
 * 
 * This library is distributed under a modified BSD license.  See the included
 * RSyntaxTextArea.License.txt file for details.
 */
package org.fife.ui.rsyntaxtextarea.parser;

import javax.swing.text.Document;
import javax.swing.text.Element;
import javax.xml.parsers.FactoryConfigurationError;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.*;
import org.xml.sax.helpers.*;

import org.fife.io.DocumentReader;
import org.fife.ui.rsyntaxtextarea.RSyntaxDocument;


/**
 * A parser for XML documents.  Adds squiggle underlines for any XML errors
 * found (though most XML parsers don't really have error recovery and so only
 * can find one error at a time).<p>
 *
 * This class isn't actually used by RSyntaxTextArea anywhere, but you can
 * install and use it yourself.  Doing so is as simple as:
 * 
 * <pre>
 * XmlParser xmlParser = new XmlParser();
 * textArea.addParser(xmlParser);
 * </pre>
 *
 * Also note that a single instance of this class can be installed on
 * multiple instances of <code>RSyntaxTextArea</code>.
 *
 * For a more complete XML parsing solution, see the
 * <a href="http://svn.fifesoft.com/viewvc-1.0.5/bin/cgi/viewvc.cgi/RSTALanguageSupport/trunk/?root=RSyntaxTextArea">RSTALanguageSupport
 * project</a>'s <code>XmlLanguageSupport</code> class.
 * 
 * @author Robert Futrell
 * @version 1.1
 */
public class XmlParser extends AbstractParser {

    private SAXParserFactory spf;
    private DefaultParseResult result;


    public XmlParser() {
        result = new DefaultParseResult(this);
        try {
            spf = SAXParserFactory.newInstance();
        } catch (FactoryConfigurationError fce) {
            fce.printStackTrace();
        }
    }


    /**
     * {@inheritDoc}
     */
    public ParseResult parse(RSyntaxDocument doc, String style) {

        result.clearNotices();
        Element root = doc.getDefaultRootElement();
        result.setParsedLines(0, root.getElementCount()-1);

        if (spf==null) {
            return result;
        }

        try {
            SAXParser sp = spf.newSAXParser();
            Handler handler = new Handler(doc);
            DocumentReader r = new DocumentReader(doc);
            InputSource input = new InputSource(r);
            sp.parse(input, handler);
            r.close();
        } catch (SAXParseException spe) {
            // A fatal parse error - ignore; a ParserNotice was already created.
        } catch (Exception e) {
            e.printStackTrace();
            result.addNotice(new DefaultParserNotice(this,
                    "Error parsing XML: " + e.getMessage(), 0, -1, -1));
        }

        return result;

    }


    /**
     * Callback notified when errors are found in the XML document.  Adds a
     * notice to be squiggle-underlined.
     */
    private class Handler extends DefaultHandler {

        private Document doc;

        private Handler(Document doc) {
            this.doc = doc;
        }

        private void doError(SAXParseException e, int level) {
            int line = e.getLineNumber() - 1;
            Element root = doc.getDefaultRootElement();
            Element elem = root.getElement(line);
            int offs = elem.getStartOffset();
            int len = elem.getEndOffset() - offs;
            if (line==root.getElementCount()-1) {
                len++;
            }
            DefaultParserNotice pn = new DefaultParserNotice(XmlParser.this,
                                            e.getMessage(), line, offs, len);
            pn.setLevel(level);
            result.addNotice(pn);
        }

        public void error(SAXParseException e) {
            doError(e, ParserNotice.ERROR);
        }

        public void fatalError(SAXParseException e) {
            doError(e, ParserNotice.ERROR);
        }

        public void warning(SAXParseException e) {
            doError(e, ParserNotice.WARNING);
        }

    }


}