Index: src/nongnu/cashews/rdf/Graph.java
===================================================================
RCS file: /cvsroot/cashew-s-editor/cashews/src/nongnu/cashews/rdf/Graph.java,v
retrieving revision 1.4
diff -u -3 -p -u -r1.4 Graph.java
--- src/nongnu/cashews/rdf/Graph.java	28 Mar 2005 19:29:21 -0000	1.4
+++ src/nongnu/cashews/rdf/Graph.java	4 Apr 2005 00:35:33 -0000
@@ -22,6 +22,7 @@
 package nongnu.cashews.rdf;
 
 import java.io.Serializable;
+import java.util.HashSet;
 import java.util.Set;
 
 /**
@@ -55,6 +56,14 @@ public class Graph 
   private Set<Triple> graph;
 
   /**
+   * Constructs a new empty graph.
+   */
+  public Graph()
+  {
+    graph = new HashSet<Triple>();
+  }
+
+  /**
    * Returns true if the specified object is either of type <code>Graph</code>,
    * or a sub-type, and contains an equivalent set of triples. If the specified
    * object is null, false is returned.
@@ -88,13 +97,39 @@ public class Graph 
   }
 
   /**
-   * Returns the graph of RDF triples.
+   * Returns a clone of the graph of RDF triples.
    * 
-   * @return a graph of RDF triples.
+   * @return a clone of the RDF triple graph.
    */
   public Set<Triple> getGraph()
   {
-    return graph;
+    Set<Triple> clonedSet = new HashSet<Triple>();
+    for (Triple triple : graph)
+      clonedSet.add(triple.clone());
+    return clonedSet;
+  }
+
+  /**
+   * Adds a triple to the graph.
+   *
+   * @param triple the triple to add.
+   */
+  public void addTriple(Triple triple)
+  {
+    graph.add(triple);
   }
 
+  /**
+   * Returns a textual representation of the graph.
+   *
+   * @return a textual representation.
+   */
+  public String toString()
+  {
+    return getClass().getName() +
+      "[graph = " +
+      graph +
+      "]";
+  }
+ 
 }
Index: src/nongnu/cashews/rdf/Literal.java
===================================================================
RCS file: /cvsroot/cashew-s-editor/cashews/src/nongnu/cashews/rdf/Literal.java,v
retrieving revision 1.3
diff -u -3 -p -u -r1.3 Literal.java
--- src/nongnu/cashews/rdf/Literal.java	3 Apr 2005 17:15:39 -0000	1.3
+++ src/nongnu/cashews/rdf/Literal.java	4 Apr 2005 00:35:33 -0000
@@ -85,4 +85,34 @@ public class Literal 
       "]";
   }
 
+  /**
+   * Returns a deep copy of this literal.
+   *
+   * @return a clone of the literal.
+   */
+  public Literal clone()
+  {
+    try
+      {
+	Object clonedObject = super.clone();
+	Literal clone = (Literal) clonedObject;
+	clone.setType(type.clone());
+	return clone;
+      }
+    catch (CloneNotSupportedException e)
+      {
+	throw new IllegalStateException("Unexpected exception: " + e, e);
+      }
+  }
+
+  /**
+   * Sets the type used by the literal to the one specified.
+   *
+   * @param type the new type to use.
+   */
+  public void setType(Type type)
+  {
+    this.type = type;
+  }
+
 }
Index: src/nongnu/cashews/rdf/Predicate.java
===================================================================
RCS file: /cvsroot/cashew-s-editor/cashews/src/nongnu/cashews/rdf/Predicate.java,v
retrieving revision 1.2
diff -u -3 -p -u -r1.2 Predicate.java
--- src/nongnu/cashews/rdf/Predicate.java	28 Mar 2005 19:29:21 -0000	1.2
+++ src/nongnu/cashews/rdf/Predicate.java	4 Apr 2005 00:35:33 -0000
@@ -30,6 +30,14 @@ package nongnu.cashews.rdf;
  * @see RDFURI
  */
 public interface Predicate
+  extends Cloneable
 {
 
+  /**
+   * Returns a deep copy of the predicate.
+   *
+   * @return a deep copy of the predicate.
+   */
+  Predicate clone();
+
 }
Index: src/nongnu/cashews/rdf/RDFObject.java
===================================================================
RCS file: /cvsroot/cashew-s-editor/cashews/src/nongnu/cashews/rdf/RDFObject.java,v
retrieving revision 1.2
diff -u -3 -p -u -r1.2 RDFObject.java
--- src/nongnu/cashews/rdf/RDFObject.java	28 Mar 2005 19:29:21 -0000	1.2
+++ src/nongnu/cashews/rdf/RDFObject.java	4 Apr 2005 00:35:33 -0000
@@ -33,7 +33,14 @@ package nongnu.cashews.rdf;
  * @see Literal
  */
 public interface RDFObject 
-  extends Node
+  extends Node, Cloneable
 {
 
+  /**
+   * Returns a deep copy of the object.
+   *
+   * @return a deep copy of the object.
+   */
+  RDFObject clone();
+
 }
Index: src/nongnu/cashews/rdf/RDFURI.java
===================================================================
RCS file: /cvsroot/cashew-s-editor/cashews/src/nongnu/cashews/rdf/RDFURI.java,v
retrieving revision 1.3
diff -u -3 -p -u -r1.3 RDFURI.java
--- src/nongnu/cashews/rdf/RDFURI.java	3 Apr 2005 17:15:39 -0000	1.3
+++ src/nongnu/cashews/rdf/RDFURI.java	4 Apr 2005 00:35:33 -0000
@@ -51,7 +51,7 @@ public class RDFURI 
    */
   public RDFURI(URI uri)
   {
-    this.uri = uri;
+    setURI(uri);
   }
 
   /**
@@ -84,4 +84,34 @@ public class RDFURI 
       }
   }
 
+  /**
+   * Returns a deep copy of this RDF URI.
+   *
+   * @return a clone of the RDF URI.
+   */
+  public RDFURI clone()
+  {
+    try
+      {
+	Object clonedObject = super.clone();
+	RDFURI clone = (RDFURI) clonedObject;
+	clone.setURI(getURI());
+	return clone;
+      }
+    catch (CloneNotSupportedException e)
+      {
+	throw new IllegalStateException("Unexpected exception: " + e, e);
+      }
+  }
+
+  /**
+   * Sets the URI used by this RDF URI to that specified.
+   *
+   * @param uri the new URI to use.
+   */
+  public void setURI(URI uri)
+  {
+    this.uri = uri;
+  }
+
 }
Index: src/nongnu/cashews/rdf/Subject.java
===================================================================
RCS file: /cvsroot/cashew-s-editor/cashews/src/nongnu/cashews/rdf/Subject.java,v
retrieving revision 1.2
diff -u -3 -p -u -r1.2 Subject.java
--- src/nongnu/cashews/rdf/Subject.java	28 Mar 2005 19:29:21 -0000	1.2
+++ src/nongnu/cashews/rdf/Subject.java	4 Apr 2005 00:35:33 -0000
@@ -34,7 +34,14 @@ package nongnu.cashews.rdf;
  * @see Blank
  */
 public interface Subject 
-  extends Node
+  extends Node, Cloneable
 {
 
+  /**
+   * Returns a deep copy of the subject.
+   *
+   * @return a deep copy of the subject.
+   */
+  Subject clone();
+
 }
Index: src/nongnu/cashews/rdf/Triple.java
===================================================================
RCS file: /cvsroot/cashew-s-editor/cashews/src/nongnu/cashews/rdf/Triple.java,v
retrieving revision 1.3
diff -u -3 -p -u -r1.3 Triple.java
--- src/nongnu/cashews/rdf/Triple.java	3 Apr 2005 17:15:39 -0000	1.3
+++ src/nongnu/cashews/rdf/Triple.java	4 Apr 2005 00:35:33 -0000
@@ -45,7 +45,7 @@ import java.io.Serializable;
  * @see Predicate
  */
 public class Triple 
-  implements Serializable
+  implements Serializable, Cloneable
 {
 
   /**
@@ -109,4 +109,121 @@ public class Triple 
       "]";
   }
 
+  /**
+   * Returns a deep copy of this triple.
+   *
+   * @return a clone of the triple.
+   */
+  public Triple clone()
+  {
+    try
+      {
+	Object clonedObject = super.clone();
+	Triple clone = (Triple) clonedObject;
+	clone.setSubject(subject.clone());
+	clone.setPredicate(predicate.clone());
+	clone.setObject(object.clone());
+	return clone;
+      }
+    catch (CloneNotSupportedException e)
+      {
+	throw new IllegalStateException("Unexpected exception: " + e, e);
+      }
+  }
+
+  /**
+   * Sets the subject of this triple to that specified.
+   *
+   * @param subject the new subject for this triple.
+   */
+  public void setSubject(Subject subject)
+  {
+    this.subject = subject;
+  }
+
+  /**
+   * Sets the predicate of this triple to that specified.
+   *
+   * @param predicate the new predicate for this triple.
+   */
+  public void setPredicate(Predicate predicate)
+  {
+    this.predicate = predicate;
+  }
+
+  /**
+   * Sets the object of this triple to that specified.
+   *
+   * @param object the new object for this triple.
+   */
+  public void setObject(RDFObject object)
+  {
+    this.object = object;
+  }
+
+  /**
+   * Returns true if the specified triple is equal to this one.
+   *
+   * @param object the object to compare.
+   */
+  public boolean equals(Object obj)
+  {
+    if (obj == null)
+      return false;
+    if (obj == this)
+      return true;
+    if (obj.getClass() == getClass())
+      {
+	Triple triple = (Triple) obj;
+	return subject.equals(triple.getSubject()) 
+	  && predicate.equals(triple.getPredicate())
+	  && object.equals(triple.getObject());
+      }
+    return false;
+  }
+
+  /**
+   * Returns the hashcode of this triple. This is calculated using
+   * the hash codes of the subject, predicate and object.
+   * 
+   * @return the hashcode for the triple.
+   */
+  public int hashCode()
+  {
+    return super.hashCode() 
+      + 13 * subject.hashCode()
+      + 17 * predicate.hashCode()
+      + 19 * object.hashCode();
+  }
+
+  /**
+   * Returns a clone of the triple's subject.
+   *
+   * @return a clone of the subject.
+   */
+  public Subject getSubject()
+  {
+    return subject.clone();
+  }
+
+  /**
+   * Returns a clone of the triple's predicate.
+   *
+   * @return a clone of the predicate.
+   */
+  public Predicate getPredicate()
+  {
+    return predicate.clone();
+  }
+
+  /**
+   * Returns a clone of the triple's object.
+   *
+   * @return a clone of the object.
+   */
+  public RDFObject getObject()
+  {
+    return object.clone();
+  }
+
 }
Index: src/nongnu/cashews/rdf/Type.java
===================================================================
RCS file: /cvsroot/cashew-s-editor/cashews/src/nongnu/cashews/rdf/Type.java,v
retrieving revision 1.1
diff -u -3 -p -u -r1.1 Type.java
--- src/nongnu/cashews/rdf/Type.java	28 Mar 2005 19:29:21 -0000	1.1
+++ src/nongnu/cashews/rdf/Type.java	4 Apr 2005 00:35:33 -0000
@@ -43,4 +43,11 @@ public interface Type
    */
   Object getValue(String lexical);
 
+  /**
+   * Returns a deep copy of the type.
+   *
+   * @return a deep copy of the type.
+   */
+  Type clone();
+
 }
Index: src/nongnu/cashews/rdf/XMLParser.java
===================================================================
RCS file: /cvsroot/cashew-s-editor/cashews/src/nongnu/cashews/rdf/XMLParser.java,v
retrieving revision 1.3
diff -u -3 -p -u -r1.3 XMLParser.java
--- src/nongnu/cashews/rdf/XMLParser.java	3 Apr 2005 17:15:39 -0000	1.3
+++ src/nongnu/cashews/rdf/XMLParser.java	4 Apr 2005 00:35:33 -0000
@@ -65,6 +65,13 @@ public class XMLParser
   private XMLReader reader;
 
   /**
+   * The resulting graph.
+   *
+   * @serial the graph of RDF triples.
+   */
+  private Graph graph;
+  
+  /**
    * Constructs a new XML-based RDF parser, using the specified handler
    * for messages.
    *
@@ -83,39 +90,46 @@ public class XMLParser
    * Parse an RDF document from the specified system identifier (URI).
    *
    * @param systemId the URI of the RDF document.
+   * @return the graph generated by the parsing process.
    * @throws SAXException if an error occurs in parsing.
    * @throws IOException if an error occurs in the underlying input.
    */
-  public void parse(String systemId)
+  public Graph parse(String systemId)
     throws IOException, SAXException
   {
+    graph = new Graph();
     reader.parse(systemId);
+    return graph;
   }
 
   /**
    * Parse an RDF document from the specified input source.
    *
    * @param source the source of the RDF document.
+   * @return the graph generated by the parsing process.
    * @throws SAXException if an error occurs in parsing.
    * @throws IOException if an error occurs in the underlying input.
    */
-  public void parse(InputSource source)
+  public Graph parse(InputSource source)
     throws IOException, SAXException
   {
+    graph = new Graph();
     reader.parse(source);
+    return graph;
   }
 
   /**
    * Parse an RDF document from the specified file.
    *
    * @param file the file containing the RDF document.
+   * @return the graph generated by the parsing process.
    * @throws SAXException if an error occurs in parsing.
    * @throws IOException if an error occurs in the underlying input.
    */
-  public void parse(File file)
+  public Graph parse(File file)
     throws IOException, SAXException
   {
-    parse(new InputSource(new FileInputStream(file)));
+    return parse(new InputSource(new FileInputStream(file)));
   }
 
   /**
@@ -136,7 +150,7 @@ public class XMLParser
     handler.setLevel(Level.FINE);
     XMLParser parser = new XMLParser(handler);
     for (int a = 0; a < args.length; ++a)
-	parser.parse(new File(args[a]));
+	System.out.println(parser.parse(new File(args[a])));
   }
 
   /**
@@ -247,20 +261,21 @@ public class XMLParser
 	{
 	  if (localName.equals("RDF"))
 	    {
+	      /* rdf:RDF */
 	      inRDF = true;
 	      logger.finer("Start of RDF block");
 	    }
 	  else if (localName.equals("Description"))
 	    {
+	      /* rdf:Description */
 	      logger.finer("Start of RDF description block");
 	      inRDF = true;
 	      if (!inSubject)
 		{
+		  /* Check for RDF URI subject */
 		  String value = attributes.getValue(RDF_NAMESPACE, "about");
 		  if (value != null)
-		    {
 		      subject = parseRDFURI(value);
-		    }
 		  inSubject = true;
 		  logger.fine("Created subject: " + subject);
 		}
@@ -273,12 +288,20 @@ public class XMLParser
 	{
 	  if (inSubject)
 	    {
+	      /* Predicate element */
 	      predicateURI = uri + localName;
 	      logger.finer("Start of predicate: " + predicateURI);
 	      predicate = parseRDFURI(predicateURI);
 	      logger.fine("Created predicate: " + predicate);
 	      inSubject = false;
 	      inPredicate = true;
+	      /* Check for RDF URI object */
+	      String value = attributes.getValue(RDF_NAMESPACE, "resource");
+	      if (value != null)
+		{
+		  object = parseRDFURI(value);
+		  logger.fine("Created object: " + object);
+		}
 	    }
 	}
     }
@@ -350,8 +373,6 @@ public class XMLParser
 	  else if (localName.equals("Description"))
 	    {
 	      logger.finer("End of description block");
-	      triple = new Triple(subject, predicate, object);
-	      logger.fine("Created triple: " + triple);
 	      inSubject = false;
 	    }
 	}
@@ -360,6 +381,9 @@ public class XMLParser
 	inPredicate = false;
 	inSubject = true;
 	predicateURI = null;
+	triple = new Triple(subject, predicate, object);
+	logger.fine("Created triple: " + triple);
+	graph.addTriple(triple);
 	logger.finer("End of predicate block");
       }
     }