client: use universal reference in data decoder

Our MsgPack decoder allows to pass rvalue reference - it is needed to
use tags like `mpp::as_raw` or handy `std::forward_as_tuple` helper.
However, we accept only lvalues in the data decoder, hence, client
cannot use those features of MsgPack decoder. Let's accept universal
reference instead to accept both lvalues and rvalues in client data
decoder - do not forget to use `std::forward` for perfect passing.

Closes #106

Author: drewdzzz

src/Client/ResponseReader.hpp

@@ -102,10 +102,10 @@ struct Data {
 
 	/** Unpacks tuples to passed container. */
 	template<class T>
-	bool decode(T& tuples)
+	bool decode(T&& tuples)
 	{
 		it_t itr = iters.first;
-		bool ok = mpp::decode(itr, tuples);
+		bool ok = mpp::decode(itr, std::forward<T>(tuples));
 		assert(!ok || itr == iters.second);
 		return ok;
 	}

test/ClientTest.cpp

@@ -1125,6 +1125,17 @@ response_decoding(Connector<BUFFER, NetProvider> &client)
 	fail_if(response->body.data->decode(arr_of_str));
 	/* We should successfully decode data after all. */
 	fail_unless(response->body.data->decode(arr_of_num));
+	fail_unless(std::get<0>(arr_of_num) == 666);
+
+	TEST_CASE("decode data to rvalue object");
+	num = 0;
+	fail_unless(response->body.data->decode(std::forward_as_tuple(num)));
+	fail_unless(num == 666);
+
+	TEST_CASE("decode data to object with an mpp tag");
+	std::get<0>(arr_of_num) = 0;
+	fail_unless(response->body.data->decode(mpp::as_arr(arr_of_num)));
+	fail_unless(std::get<0>(arr_of_num) == 666);
 
 	client.close(conn);
 }