Fix misuse of getAttributeNS(), and handling of xml:lang.

Note to self: getAttributeNS() returns "", not null, when the
attribute is nonexistent.

Also, the XML spec (now) clearly states that "" is used for an
unknown/undefined language.

1 files changed, 16 insertions, 8 deletions

diff --git a/org/madore/damlengine/LangHelper.java b/org/madore/damlengine/LangHelper.java
index 280e5ca..e2a74db 100644
--- a/org/madore/damlengine/LangHelper.java
+++ b/org/madore/damlengine/LangHelper.java
@@ -2,15 +2,23 @@ package org.madore.damlengine;
 
 import org.w3c.dom.Node;
 import org.w3c.dom.Element;
+import org.w3c.dom.Attr;
 
 public class LangHelper {
 
     public static final String LANG = "lang";
 
     public static String getLangNorec(Node node) {
-	if ( node instanceof Element )
-	    return ((Element)node).getAttributeNS(DamlEngine.XML_NS, LANG);
-	else
+	// Returns null when no xml:lang attribute is found,
+	// otherwise, returns its value.
+	if ( node instanceof Element ) {
+	    Attr lang = ((Element)node).
+		getAttributeNodeNS(DamlEngine.XML_NS, LANG);
+	    if ( lang == null )
+		return null;
+	    else
+		return lang.getValue();
+	} else
 	    return null;
     }
 
@@ -25,22 +33,22 @@ public class LangHelper {
     }
 
     public static String getLangRec(Node node) {
-	// node may be null (in which case, return null)
+	// Never returns null (returns the empty string for no language).
+	// node may be null (in which case, return "").
 	while ( node != null ) {
 	    String lang = getLangNorec(node);
 	    if ( lang != null )
 		return lang;
 	    node = node.getParentNode();
 	}
-	return null;
+	return "";
     }
 
     public static void setLangRec(Element node, String lang) {
 	if ( lang == null )
 	    throw new Error("lang is null in setLangRec");
-	Node parentNode = node.getParentNode();
-	String parentLang = (parentNode!=null)?getLangNorec(parentNode):null;
-	if ( parentLang != null && lang.equals(parentLang) )
+	String parentLang = getLangRec(node.getParentNode());
+	if ( lang.equals(parentLang) )
 	    unsetLangNorec(node);
 	else
 	    setLangNorec(node,lang);