Add and use xml_scoped_ptr helper.

vslavik · Jul 4, 2013 · e5bb7ea · e5bb7ea
1 parent ea82953
commit e5bb7ea
Show file tree

Hide file tree

Showing 2 changed files with 23 additions and 8 deletions.
diff --git a/src/libxml/utility.h b/src/libxml/utility.h
@@ -48,6 +48,27 @@ namespace xml
 namespace impl
 {
 
+// Helper for holding libxml objects with guaranteed freeing
+template<typename TPtr, void (*FreeFunc)(TPtr)>
+class xml_scoped_ptr
+{
+public:
+    explicit xml_scoped_ptr(TPtr ptr) : ptr_(ptr) {}
+
+    ~xml_scoped_ptr()
+    {
+        if (ptr_)
+            FreeFunc(ptr_);
+    }
+
+    TPtr operator->() const { return ptr_; }
+    TPtr get() const { return ptr_; }
+    operator TPtr() const { return ptr_; }
+
+private:
+    TPtr ptr_;
+};
+
 // exception safe wrapper around xmlChar*s that are returned from some
 // of the libxml functions that the user must free.
 class xmlchar_helper

diff --git a/src/libxml/xpath.cxx b/src/libxml/xpath.cxx
@@ -69,8 +69,6 @@ class nodeset_next_functor : public impl::iter_advance_functor
 
         for ( size_t i = 0; i < length-1; i++ )
             m_next[table[i]] = table[i+1];
-
-        xmlXPathFreeObject(pathobj);
     }
 
     virtual xmlNodePtr operator()(xmlNodePtr node) const
@@ -104,20 +102,16 @@ struct xpath_context_impl
     template<typename NodesView>
     NodesView evaluate(const std::string& expr, node& n)
     {
-        // TODO: use auto ptr for this
-        xmlXPathObjectPtr nsptr =
+        xml_scoped_ptr<xmlXPathObjectPtr, xmlXPathFreeObject> nsptr(
             xmlXPathNodeEval(reinterpret_cast<xmlNodePtr>(n.get_node_data()),
-                             ctxt_);
                              xml_string(expr),
+                             ctxt_));
 
         if ( !nsptr )
             return NodesView();
 
         if ( xmlXPathNodeSetIsEmpty(nsptr->nodesetval) )
-        {
-            xmlXPathFreeObject(nsptr);
             return NodesView();
-        }
 
         return NodesView(nsptr->nodesetval->nodeTab[0],
                          new nodeset_next_functor(nsptr));