--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/artifact-database/src/main/java/de/intevation/artifactdatabase/ProxyArtifact.java	Mon Nov 23 11:15:44 2009 +0000
@@ -0,0 +1,116 @@
+package de.intevation.artifactdatabase;
+
+import org.w3c.dom.Document;
+
+import de.intevation.artifacts.Artifact;
+import de.intevation.artifacts.CallContext;
+import de.intevation.artifacts.ArtifactFactory;
+
+import org.apache.log4j.Logger;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+/**
+ * @author Sascha L. Teichmann (sascha.teichmann@intevation.de)
+ */
+public class ProxyArtifact
+extends      DefaultArtifact
+{
+    public static final Object REPLACE_PROXY = new Object();
+
+    private static Logger logger = Logger.getLogger(ProxyArtifact.class);
+
+    protected Artifact proxied;
+
+    public ProxyArtifact() {
+    }
+
+    public ProxyArtifact(Artifact proxied) {
+        this.proxied = proxied;
+    }
+
+    public Artifact getProxied() {
+        return proxied;
+    }
+
+    public void setProxied(Artifact proxied) {
+        this.proxied = proxied;
+    }
+
+    protected void checkReplacement(CallContext callContext) {
+        Object replacement = callContext.getContextValue(REPLACE_PROXY);
+        if (replacement instanceof Artifact) {
+            setProxied((Artifact)replacement);
+        }
+    }
+
+    public String hash() {
+        return proxied != null
+            ? proxied.hash()
+            : super.hash();
+    }
+
+    public Document describe(Document data, CallContext context) {
+        try {
+            return proxied != null
+                ? proxied.describe(data, context)
+                : super.describe(data, context);
+        }
+        finally {
+            checkReplacement(context);
+        }
+    }
+
+    public Document advance(Document target, CallContext context) {
+        try {
+            return proxied != null
+                ? proxied.advance(target, context)
+                : super.advance(target, context);
+        }
+        finally {
+            checkReplacement(context);
+        }
+    }
+
+    public Document feed(Document target, CallContext context) {
+        try {
+            return proxied != null 
+                ? proxied.feed(target, context)
+                : super.feed(target, context);
+        }
+        finally {
+            checkReplacement(context);
+        }
+    }
+
+    public void out(
+        Document     format,
+        OutputStream out,
+        CallContext  context
+    )
+    throws IOException
+    {
+        try {
+            if (proxied != null) {
+                proxied.out(format, out, context);
+            }
+            else {
+                super.out(format, out, context);
+            }
+        }
+        finally {
+            checkReplacement(context);
+        }
+    }
+
+    public void endOfLife(Object context) {
+        if (proxied != null) {
+            proxied.endOfLife(context);
+        }
+        else {
+            super.endOfLife(context);
+        }
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8: