Use static_cast instead of C-style casts, make local variables const where…

Use static_cast instead of C-style casts, make local variables const where possible, use switch instead of chained if/else, extract rm_helper_multiple_subnodes from rm_helper to reduce nesting

src/generic_mtrie.hpp

@@ -92,6 +92,17 @@ template <typename T> class generic_mtrie_t
                     void (*func_) (prefix_t data_, size_t size_, Arg arg_),
                     Arg arg_,
                     bool call_on_uniq_);
+    template <typename Arg>
+    void rm_helper_multiple_subnodes (unsigned char **buff_,
+                                      size_t buffsize_,
+                                      size_t maxbuffsize_,
+                                      void (*func_) (prefix_t data_,
+                                                     size_t size_,
+                                                     Arg arg_),
+                                      Arg arg_,
+                                      bool call_on_uniq_,
+                                      value_t *pipe_);
+
     rm_result rm_helper (prefix_t prefix_, size_t size_, value_t *value_);
     bool is_redundant () const;