1 files changed, 108 insertions, 7 deletions

diff --git a/src/main/java/org/openslx/util/XmlHelper.java b/src/main/java/org/openslx/util/XmlHelper.java
index 70c5be8..90d282b 100644
--- a/src/main/java/org/openslx/util/XmlHelper.java
+++ b/src/main/java/org/openslx/util/XmlHelper.java
@@ -3,6 +3,8 @@ package org.openslx.util;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.StringWriter;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
@@ -14,24 +16,29 @@ import javax.xml.transform.dom.DOMSource;
 import javax.xml.transform.stream.StreamResult;
 import javax.xml.xpath.XPath;
 import javax.xml.xpath.XPathConstants;
+import javax.xml.xpath.XPathExpression;
 import javax.xml.xpath.XPathExpressionException;
 import javax.xml.xpath.XPathFactory;
 
-import org.apache.log4j.Logger;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.w3c.dom.Attr;
 import org.w3c.dom.Document;
+import org.w3c.dom.Element;
 import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;
 import org.xml.sax.SAXException;
 
 public class XmlHelper
 {
-	private final static Logger LOGGER = Logger.getLogger( XmlHelper.class );
+	private final static Logger LOGGER = LogManager.getLogger( XmlHelper.class );
 
 	// TODO check thread-safety
-	public static final XPath XPath = XPathFactory.newInstance().newXPath();
+	private static final XPath XPath = XPathFactory.newInstance().newXPath();
 	private static DocumentBuilder dBuilder;
 	static {
 		DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
+		dbFactory.setNamespaceAware( true );
 		dbFactory.setIgnoringComments( true );
 		try {
 			dBuilder = dbFactory.newDocumentBuilder();
@@ -40,17 +47,64 @@ public class XmlHelper
 		}
 	}
 
+	public static String globalXPathToLocalXPath( String xPath )
+	{
+		final StringBuilder exprBuilder = new StringBuilder();
+		final String[] elements = xPath.split( "/" );
+
+		for ( final String element : elements ) {
+			if ( !element.isEmpty() ) {
+				final Pattern arraySpecifierRegex = Pattern.compile( "^(.*)\\[(.*)\\]$" );
+				final Matcher arraySpecifierMatcher = arraySpecifierRegex.matcher( element );
+				final String elementName;
+				final String elementSpecifier;
+
+				if ( arraySpecifierMatcher.find() ) {
+					elementName = arraySpecifierMatcher.group( 1 );
+					elementSpecifier = arraySpecifierMatcher.group( 2 );
+				} else {
+					elementName = element;
+					elementSpecifier = null;
+				}
+
+				if ( !elementName.startsWith( "@" ) && !elementName.equals( "*" ) ) {
+					exprBuilder.append( "/*[local-name()='" + elementName + "']" );
+
+				} else {
+					exprBuilder.append( "/" + elementName );
+				}
+
+				if ( elementSpecifier != null && !elementSpecifier.isEmpty() ) {
+					exprBuilder.append( "[" + elementSpecifier + "]" );
+				}
+			}
+		}
+
+		return exprBuilder.toString();
+	}
+
+	public static XPathExpression compileXPath( String xPath ) throws XPathExpressionException
+	{
+		final String localXPath = XmlHelper.globalXPathToLocalXPath( xPath );
+		return XPath.compile( localXPath );
+	}
+
 	public static Document parseDocumentFromStream( InputStream is )
 	{
 		Document doc = null;
+
+		// read document from stream
 		try {
 			doc = dBuilder.parse( is );
 		} catch ( SAXException | IOException e ) {
-			LOGGER.error( "Failed to parse input stream to document." );
+			doc = null;
 		}
-		if ( doc == null )
-			return null;
-		doc.getDocumentElement().normalize();
+
+		// normalize parsed document
+		if ( doc != null ) {
+			doc.getDocumentElement().normalize();
+		}
+
 		return doc;
 	}
 
@@ -105,4 +159,51 @@ public class XmlHelper
 			return null;
 		}
 	}
+
+	public static Element getOrCreateElement( Document doc, Element parent, String nsUri, String nsName,
+			String name, String attrName, String attrValue )
+	{
+		final NodeList childList;
+		if ( nsUri == null ) {
+			childList = parent.getElementsByTagName( name );
+		} else {
+			childList = parent.getElementsByTagNameNS( nsUri, name );
+		}
+		Element element = null;
+		outer: for ( int i = 0; i < childList.getLength(); ++i ) {
+			Node n = childList.item( i );
+			if ( n.getNodeType() != Node.ELEMENT_NODE )
+				continue;
+			if ( attrName != null && attrValue != null ) {
+				for ( int ai = 0; ai < n.getAttributes().getLength(); ++ai ) {
+					Node attr = n.getAttributes().item( ai );
+					if ( attr.getNodeType() != Attr.ELEMENT_NODE )
+						continue;
+					Attr a = (Attr)attr;
+					if ( !attrName.equals( a.getLocalName() ) || !attrValue.equals( a.getValue() ) )
+						continue;
+					element = (Element)n;
+					break outer;
+				}
+			} else {
+				element = (Element)n;
+				break;
+			}
+		}
+		if ( element == null ) {
+			// Need a new <qemu:device alias="hostdev0">
+			if ( nsUri == null || nsName == null ) {
+				element = doc.createElement( name );
+			} else {
+				element = doc.createElementNS( nsUri, name );
+				element.setPrefix( nsName );
+			}
+			if ( attrName != null && attrValue != null ) {
+				element.setAttribute( attrName, attrValue );
+			}
+			parent.appendChild( element );
+		}
+		return element;
+	}
+
 }