Added sequence diagram model cleanup step to remove empty block statements

src/sequence_diagram/model/diagram.h

@@ -212,6 +212,15 @@ public:
      */
     bool should_include(const sequence_diagram::model::participant &p) const;
 
+    /**
+     * @brief Once the diagram is complete, run any final processing.
+     *
+     * This method should be overriden by specific diagram models to do some
+     * final tasks like cleaning up the model (e.g. some filters only work
+     * on completed diagrams).
+     */
+    void finalize() override;
+
 private:
     /**
      * This method checks the last messages in sequence (current_messages),
@@ -233,6 +242,27 @@ private:
         common::model::message_t statement_begin,
         std::vector<message> &current_messages) const;
 
+    bool is_begin_block_message(common::model::message_t mt)
+    {
+        using common::model::message_t;
+        static std::set<message_t> block_begin_types{message_t::kIf,
+            message_t::kWhile, message_t::kDo, message_t::kFor, message_t::kTry,
+            message_t::kSwitch, message_t::kConditional};
+
+        return block_begin_types.count(mt) > 0;
+    };
+
+    bool is_end_block_message(common::model::message_t mt)
+    {
+        using common::model::message_t;
+        static std::set<message_t> block_end_types{message_t::kIfEnd,
+            message_t::kWhileEnd, message_t::kDoEnd, message_t::kForEnd,
+            message_t::kTryEnd, message_t::kSwitchEnd,
+            message_t::kConditionalEnd};
+
+        return block_end_types.count(mt) > 0;
+    };
+
     bool started_{false};
 
     std::map<common::model::diagram_element::id_t, activity> sequences_;