added a function lookup framework


	* xpath.c include/libxml/xpath{,Internals}.h: added a function
	  lookup framework
diff --git a/include/libxml/xpath.h b/include/libxml/xpath.h
index a3c925a..8d921f8 100644
--- a/include/libxml/xpath.h
+++ b/include/libxml/xpath.h
@@ -231,6 +231,10 @@
     /* The function name and URI when calling a function */
     const xmlChar *function;
     const xmlChar *functionURI;
+
+    /* function lookup function and data */
+    void *funcLookupFunc;		/* function lookup func */
+    void *funcLookupData;		/* function lookup data */
 };
 
 /*
diff --git a/include/libxml/xpathInternals.h b/include/libxml/xpathInternals.h
index ca3943f..63f3609 100644
--- a/include/libxml/xpathInternals.h
+++ b/include/libxml/xpathInternals.h
@@ -320,6 +320,18 @@
 					 void *varCtxt);
 
 /*
+ * Function Lookup forwarding
+ */
+typedef xmlXPathFunction
+	(*xmlXPathFuncLookupFunc)	(void *ctxt,
+					 const xmlChar *name,
+					 const xmlChar *ns_uri);
+
+void	xmlXPathRegisterFuncLookup	(xmlXPathContextPtr ctxt,
+					 xmlXPathFuncLookupFunc f,
+					 void *funcCtxt);
+
+/*
  * Error reporting
  */
 void		xmlXPatherror	(xmlXPathParserContextPtr ctxt,