Ticket #6876: add_forwarding_to_ref.patch

ref.hpp

@@ -12 +12 @@
 #include <boost/mpl/bool.hpp>
 #include <boost/detail/workaround.hpp>
 
+// operator() forwarding
+#include <boost/preprocessor/cat.hpp>
+#include <boost/preprocessor/repetition/repeat_from_to.hpp>
+#include <boost/preprocessor/repetition/enum.hpp>
+#include <boost/preprocessor/repetition/enum_params.hpp>
+#include <boost/preprocessor/tuple/elem.hpp>
+
+#include <boost/utility/result_of.hpp>
+#include <boost/move/move.hpp>
+
 //
 //  ref.hpp - ref/cref, useful helper functions
 //
@@ -50 +60 @@
 
     T* get_pointer() const { return t_; }
 
+#define FWD_REF(z, n, name) BOOST_PP_CAT(BOOST_FWD_REF(BOOST_PP_CAT(BOOST_PP_TUPLE_ELEM(2, 0, name), n)) BOOST_PP_TUPLE_ELEM(2, 1, name), n)
+#define FWD(x, y) boost::forward<x>(y)
+#define FWDER(z, n, x) FWD(BOOST_PP_CAT(BOOST_PP_TUPLE_ELEM(2, 0, x), n), BOOST_PP_CAT(BOOST_PP_TUPLE_ELEM(2, 1, x), n))
+
+#define FN(z, n, data)                                                    \
+    template<BOOST_PP_ENUM_PARAMS(n, class T)>                            \
+    typename boost::result_of<T( BOOST_PP_ENUM_PARAMS(n, T) )>::type      \
+    operator()( BOOST_PP_ENUM(n, FWD_REF, (T, t) ) )                      \
+    {                                                                     \
+      return t_->operator()(BOOST_PP_ENUM(n, FWDER, (T, t) ));            \
+    }                                                                     \
+
+    // null-ary written without FN macro to prevent no-argument template
+    typename boost::result_of<T()>::type
+    operator()()
+    {
+      return t_->operator()();
+    }
+
+    // TODO make argument length configurable
+    BOOST_PP_REPEAT_FROM_TO(1, 8, FN, _);
+
+#undef FWD_REF
+#undef FWD
+#undef FWDER
+#undef FN
+
 private:
 
     T* t_;