Initial go at out of order loading working

include/cereal/archives/xml.hpp

@@ -309,7 +309,23 @@ namespace cereal
       //! Prepares to start reading the next node
       void startNode()
       {
-        itsNodes.emplace( itsNodes.top().child );
+        auto next = itsNodes.top().child;
+        auto const expectedName = itsNodes.top().name;
+
+        std::cerr << "Expected name was " << expectedName << ", actual name was: " << next->name() << std::endl;
+
+        // If the expected name does not match the loaded name, try to load the NVP name
+        // If we can't find the NVP name, throw an exception
+        if( expectedName && std::strcmp( next->name(), expectedName ) != 0 )
+        {
+          std::cerr << "Loading " << expectedName << std::endl;
+          next = itsXML.first_node( expectedName );
+          if( next == nullptr )
+            throw Exception("XML Parsing failed - provided NVP not found");
+        }
+
+        itsNodes.emplace( next );
+        //itsNodes.emplace( itsNodes.top().child );
       }
 
       //! Finishes reading the current node
@@ -320,6 +336,16 @@ namespace cereal
 
         // advance parent
         itsNodes.top().advance();
+
+        // Reset name
+        itsNodes.top().name = nullptr;
+      }
+
+      //! Sets the name for the next node created with startNode
+      void setNextName( const char * name )
+      {
+        std::cerr << "Setting next name to be " << name << std::endl;
+        itsNodes.top().name = name;
       }
 
       //! Loads a bool
@@ -450,7 +476,8 @@ namespace cereal
         NodeInfo( rapidxml::xml_node<> * n = nullptr ) :
           node( n ),
           child( n ? n->first_node() : nullptr ),
-          size( XMLInputArchive::getNumChildren( n ) )
+          size( XMLInputArchive::getNumChildren( n ) ),
+          name( nullptr )
         { }
 
         void advance()
@@ -465,6 +492,7 @@ namespace cereal
         rapidxml::xml_node<> * node;  //!< A pointer to this node
         rapidxml::xml_node<> * child; //!< A pointer to its current child
         size_t size;
+        const char * name;            //!< The NVP name for next next child node
       }; // NodeInfo
 
     private:
@@ -574,6 +602,7 @@ namespace cereal
   template <class T> inline
   void load( XMLInputArchive & ar, NameValuePair<T> & t )
   {
+    ar.setNextName( t.name );
     ar( t.value );
   }
 

sandbox.cpp

@@ -500,6 +500,50 @@ int main()
     std::remove("endian.out");
   }
 
+  {
+    std::ofstream ss("xml_ordering.out");
+    cereal::XMLOutputArchive ar(ss);
+
+    double one = 1;
+    double two = 2;
+    double three = 3;
+    std::vector<int> four = {1, 2, 3, 4};
+
+    // Output is ordered 3 2 1 4
+    ar( three, CEREAL_NVP(two), one, cereal::make_nvp("five", four) );
+  }
+
+  {
+    std::ifstream ss("xml_ordering.out");
+    cereal::XMLInputArchive ar(ss);
+
+    // Output prodered out of order, try to load in order 1 2 3 4
+    double one;
+    double two;
+    double three;
+    std::vector<int> four;
+
+    ar( one ); // cereal can only give warnings if you used an NVP!
+    ar( CEREAL_NVP( two ) );
+    ar( three );
+
+    try
+    {
+      ar( CEREAL_NVP( three ) );
+    }
+    catch( cereal::Exception const & e )
+    {
+      std::cout << e.what() << std::endl;
+      std::cout << "Looked for three but we didn't use an NVP when saving" << std::endl;
+    }
+    ar( cereal::make_nvp("five", four) );
+
+    std::cout << one << std::endl;
+    std::cout << two << std::endl;
+    std::cout << three << std::endl;
+    for( auto i : four ) std::cout << i << " ";
+    std::cout << std::endl;
+  }
 
 
   return 0;