DPL Analysis: Add pack selection based on condition with multiple parameters

Author: saganatt

Framework/Foundation/include/Framework/Pack.h

@@ -100,24 +100,28 @@ template <typename P1, typename P2>
 using interleaved_pack_t = decltype(interleave_pack(P1{}, P2{}));
 
 /// Selects from the pack types that satisfy the Condition
-template <template <typename> typename Condition, typename Result>
-constexpr auto select_pack(Result result, pack<>)
+/// Multicondition takes the type to check as first template parameter
+/// and any helper types as the following parameters
+template <template <typename...> typename Condition, typename Result, typename... Cs>
+constexpr auto select_pack(Result result, pack<>, pack<Cs...>)
 {
   return result;
 }
 
-template <template <typename> typename Condition, typename Result, typename T, typename... Ts>
-constexpr auto select_pack(Result result, pack<T, Ts...>)
+template <template <typename...> typename Condition, typename Result, typename T, typename... Cs, typename... Ts>
+constexpr auto select_pack(Result result, pack<T, Ts...>, pack<Cs...> condPack)
 {
-  if constexpr (Condition<T>()) {
-    return select_pack<Condition>(concatenate_pack(result, pack<T>{}), pack<Ts...>{});
+  if constexpr (Condition<T, Cs...>()) {
+    return select_pack<Condition>(concatenate_pack(result, pack<T>{}), pack<Ts...>{}, condPack);
   } else {
-    return select_pack<Condition>(result, pack<Ts...>{});
+    return select_pack<Condition>(result, pack<Ts...>{}, condPack);
   }
 }
 
-template <template <typename> typename Condition, typename... Types>
-using selected_pack = std::decay_t<decltype(select_pack<Condition>(pack<>{}, pack<Types...>{}))>;
+template <template <typename...> typename Condition, typename... Types>
+using selected_pack = std::decay_t<decltype(select_pack<Condition>(pack<>{}, pack<Types...>{}, pack<>{}))>;
+template <template <typename...> typename Condition, typename CondPack, typename Pack>
+using selected_pack_multicondition = std::decay_t<decltype(select_pack<Condition>(pack<>{}, Pack{}, CondPack{}))>;
 
 /// Select only the items of a pack which match Condition
 template <template <typename> typename Condition, typename Result>

Framework/Foundation/test/test_FunctionalHelpers.cxx

@@ -23,6 +23,9 @@ using namespace o2::framework;
 template <typename T>
 using is_int_t = std::is_same<typename std::decay_t<T>, int>;
 
+template <typename T, typename T2>
+using is_same_as_second_t = std::is_same<typename std::decay_t<T>, T2>;
+
 template <int A, int B>
 struct TestStruct {
 };
@@ -36,6 +39,7 @@ BOOST_AUTO_TEST_CASE(TestOverride)
   static_assert(has_type_at<double>(pck) == pack_size(pck) + 1, "double is not in the pack so the function returns size + 1");
 
   static_assert(std::is_same_v<selected_pack<is_int_t, int, float, char>, pack<int>>, "selector should select int");
+  static_assert(std::is_same_v<selected_pack_multicondition<is_same_as_second_t, pack<int>, pack<int, float, char>>, pack<int>>, "multiselector should select int");
   static_assert(std::is_same_v<filtered_pack<is_int_t, int, float, char>, pack<float, char>>, "filter should remove int");
   static_assert(std::is_same_v<intersected_pack_t<pack<int, float, char>, pack<float, double>>, pack<float>>, "filter intersect two packs");
   static_assert(has_type_v<pack_element_t<0, pack<int>>, pack<int>> == true, "foo");