Add OhmmsXPathObject constructor that can be used with the current xml node.

It is expensive and don't abuse it.
OhmmsXPathObject det("//determinant",cur);



git-svn-id: https://subversion.assembla.com/svn/qmcdev/trunk@6054 e5b18d87-469d-4833-9cc0-8cdfa06e9491

src/OhmmsData/Libxml2Doc.cpp

@@ -20,7 +20,7 @@
 #include "Utilities/Timer.h"
 #include <fstream>
 
-OhmmsXPathObject::OhmmsXPathObject(): NumObjects(0), result(NULL)
+OhmmsXPathObject::OhmmsXPathObject(): NumObjects(0), result(NULL),m_context(NULL)
 {
 }
 
@@ -30,12 +30,23 @@ OhmmsXPathObject::OhmmsXPathObject(const char* expression,
   put(expression, context);
 }
 
+OhmmsXPathObject::OhmmsXPathObject(const char* expression, xmlNodePtr cur) :NumObjects(0), result(NULL)
+{
+  m_context= xmlXPathNewContext(cur->doc);
+  put(expression, m_context);
+}
+
 OhmmsXPathObject::~OhmmsXPathObject()
 {
   if(result != NULL)
   {
     xmlXPathFreeObject(result);
   }
+
+  if(m_context != NULL)
+  {
+    xmlXPathFreeContext(m_context);
+  }
 }
 
 void OhmmsXPathObject::put(const char* expression, xmlXPathContextPtr context)
@@ -54,6 +65,7 @@ void OhmmsXPathObject::put(const char* expression, xmlXPathContextPtr context)
   }
 }
 
+
 Libxml2Document::Libxml2Document(): m_doc(NULL), m_root(NULL),
   m_context(NULL) { }
 

src/OhmmsData/Libxml2Doc.h

@@ -32,6 +32,14 @@ struct OhmmsXPathObject
    */
   OhmmsXPathObject(const char* expression, xmlXPathContextPtr context);
 
+  /** constructor
+   * @param expression  xpath expression
+   * @param cur xmlNodePtr
+   *
+   * Create m_context 
+   */
+  OhmmsXPathObject(const char* expression, xmlNodePtr cur);
+
   ~OhmmsXPathObject();
 
   /** evaluate the expression and create the object
@@ -64,6 +72,7 @@ struct OhmmsXPathObject
 
   int NumObjects;
   xmlXPathObjectPtr result;
+  xmlXPathContextPtr m_context;
 };
 
 /** class that handles xmlDoc