[engine.i] VECTORREF_HELPER_INOUT to handle SplitsVec&

bindings/engine.i

@@ -86,6 +86,7 @@ GLIST_HELPER_INOUT(PriceList, SWIGTYPE_p_GNCPrice);
 // TODO: free PriceList?
 GLIST_HELPER_INOUT(CommodityList, SWIGTYPE_p_gnc_commodity);
 VECTOR_HELPER_INOUT(SplitsVec, SWIGTYPE_p_Split, Split);
+VECTORREF_HELPER_INOUT(SplitsVec&, SWIGTYPE_p_Split, Split);
 VECTOR_HELPER_INOUT(AccountVec, SWIGTYPE_p_Account, Account);
 
 %typemap(newfree) char * "g_free($1);"

common/base-typemaps.i

@@ -185,6 +185,15 @@ typedef char gchar;
 }
 %enddef
 
+
+%define VECTORREF_HELPER_INOUT(VectorType, ElemSwigType, ElemType)
+
+%typemap(out) VectorType {
+    auto accum = [](SCM acc, auto n){ return scm_cons(SWIG_NewPointerObj(n, ElemSwigType, 0), acc); };
+    $result = std::accumulate ($1->rbegin(), $1->rend(), SCM_EOL, accum);
+}
+%enddef
+
 #elif defined(SWIGPYTHON) /* Typemaps for Python */
 
 %import "glib.h"