Introducing scene graph

Visitor.h

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+#ifndef VISITOR_H
+#define VISITOR_H
+
+#include <string>
+
+namespace tinyxml2 {
+class XMLDocument;
+class XMLElement;
+}
+
+// Forward declare different kind of Node
+class Node;
+class Primitive;
+class Group;
+class Scene;
+class TexturedRectangle;
+class MediaRectangle;
+class LineStrip;
+
+// Declares the interface for the visitors
+class Visitor {
+
+public:
+    // Declare overloads for each kind of Node to visit
+    virtual void visit(Node& n) = 0;
+    virtual void visit(Primitive& n) = 0;
+    virtual void visit(Group& n) = 0;
+    virtual void visit(TexturedRectangle& n) = 0;
+    virtual void visit(MediaRectangle& n) = 0;
+    virtual void visit(LineStrip& n) = 0;
+    virtual void visit(Scene& n) = 0;
+};
+
+class SessionVisitor : public Visitor {
+
+    std::string filename_;
+    tinyxml2::XMLDocument *xmlDoc_;
+    tinyxml2::XMLElement *xmlCurrent_;
+
+public:
+    SessionVisitor(std::string filename);
+
+    void visit(Node& n) override;
+    void visit(Primitive& n) override;
+    void visit(Group& n) override;
+    void visit(TexturedRectangle& n) override;
+    void visit(MediaRectangle& n) override;
+    void visit(LineStrip& n) override;
+    void visit(Scene& n) override;
+
+};
+
+#endif // VISITOR_H