Added diagram type enum

src/common/model/diagram.h

@@ -34,6 +34,8 @@ public:
     diagram();
     virtual ~diagram();
 
+    virtual diagram_t type() const = 0;
+
     diagram(const diagram &) = delete;
     diagram(diagram &&);
     diagram &operator=(const diagram &) = delete;

src/common/model/enums.h

@@ -21,6 +21,8 @@
 
 namespace clanguml::common::model {
 
+enum class diagram_t { kClass, kSequence, kPackage };
+
 enum class access_t { kPublic, kProtected, kPrivate };
 
 enum class relationship_t {