Eliminate use of DocumentBuilder (use DOM LS everywhere) + use validation to catch undefined entities.

There seems to be no way to catch the undefined entity error (when it
is considered a validation error, e.g., when the document has an
external subset) other than by turning on validation.  So we register
an error handler to throw away useless validation errors.

1 files changed, 49 insertions, 21 deletions

diff --git a/org/madore/damlengine/DamlEngine.java b/org/madore/damlengine/DamlEngine.java
index c0010b6..7bc81bd 100644
--- a/org/madore/damlengine/DamlEngine.java
+++ b/org/madore/damlengine/DamlEngine.java
@@ -1,5 +1,6 @@
 package org.madore.damlengine;
 
+import java.util.MissingResourceException;
 import java.util.regex.Pattern;
 import java.util.regex.Matcher;
 import java.io.InputStream;
@@ -12,12 +13,13 @@ import java.io.BufferedReader;
 import java.io.PrintStream;
 import javax.xml.XMLConstants;
 import javax.xml.namespace.NamespaceContext;
-import javax.xml.parsers.DocumentBuilderFactory;
-import javax.xml.parsers.DocumentBuilder;
-import javax.xml.parsers.ParserConfigurationException;
-import org.w3c.dom.Document;
-// import org.xml.sax.EntityResolver;
-import org.apache.xerces.jaxp.DocumentBuilderFactoryImpl;
+import org.w3c.dom.*;
+import org.w3c.dom.ls.DOMImplementationLS;
+import org.w3c.dom.ls.LSParser;
+import org.w3c.dom.ls.LSInput;
+import org.apache.xerces.dom.DOMImplementationSourceImpl;
+import org.apache.xerces.xni.parser.XMLErrorHandler;
+import org.apache.xerces.xni.parser.XMLParseException;
 
 public final class DamlEngine {
 
@@ -54,19 +56,37 @@ public final class DamlEngine {
 	}
     }
 
-    public static final class GetDocumentBuilder {
-	static final DocumentBuilder db;
-	static {
-	    final Resolver resolver = new Resolver();
-	    final DocumentBuilderFactory dbf = new DocumentBuilderFactoryImpl();
-	    dbf.setNamespaceAware(true);
-	    dbf.setValidating(false);
-	    try {
-		db = dbf.newDocumentBuilder();
-	    } catch (ParserConfigurationException e) {
-		throw new RuntimeException(e);
+    public static class SelectiveErrorHandler implements XMLErrorHandler {
+    	public void warning(String domain, String key, XMLParseException exc) {
+    	    System.err.println("warning: line "+exc.getLineNumber()
+			       +": "+exc.getMessage());
+    	}
+    	public void error(String domain, String key, XMLParseException exc) {
+	    if ( domain.equals("http://www.w3.org/TR/1998/REC-xml-19980210")
+		 && key.equals("MSG_ELEMENT_NOT_DECLARED") )
+		return;
+    	    System.err.println("error: line "+exc.getLineNumber()
+			       +": "+exc.getMessage());
+    	}
+    	public void fatalError(String domain, String key, XMLParseException exc) {
+    	    System.err.println("fatal error: line "+exc.getLineNumber()
+			       +": "+exc.getMessage());
+    	    throw exc;
+    	}
+    }
+
+    public static final class IncantDOM {
+	static DOMImplementation domi;
+	public static DOMImplementation getDOMI() {
+	    if ( domi == null ) {
+		DOMImplementationSource source
+		    = new DOMImplementationSourceImpl();
+		domi = source.getDOMImplementation("XML 3.0 Core 3.0 LS 3.0");
+		if ( domi == null )
+		    throw new MissingResourceException("failed to obtain DOM implementation",
+						       "org.w3c.dom.ls.DOMImplementationLS", "");
 	    }
-	    db.setEntityResolver(resolver);
+	    return domi;
 	}
     }
 
@@ -103,9 +123,17 @@ public final class DamlEngine {
 				   Context.WeblogSelectionContext wsc)
 	throws Exception {
 
-	final DocumentBuilder db = GetDocumentBuilder.db;
-
-	Document doc = db.parse(in);
+	final DOMImplementationLS domils
+	    = (DOMImplementationLS)(IncantDOM.getDOMI());
+	LSParser par
+	    = domils.createLSParser(DOMImplementationLS.MODE_SYNCHRONOUS, null);
+	par.getDomConfig().setParameter("resource-resolver", new Resolver());
+	par.getDomConfig().setParameter("http://xml.org/sax/features/validation", true);
+	par.getDomConfig().setParameter("http://xml.org/sax/features/namespaces", true);
+	par.getDomConfig().setParameter("http://apache.org/xml/properties/internal/error-handler", new SelectiveErrorHandler());
+	LSInput input = domils.createLSInput();
+	input.setByteStream(in);
+	Document doc = par.parse(input);
 	processDocument(doc, wsc);
 	doc.normalizeDocument();
 	Unparser unparser