add expression metadata to input specs

Author: aalkin

Framework/Core/include/Framework/ASoA.h

@@ -1295,6 +1295,9 @@ concept with_ccdb_urls = requires {
 template <typename T>
 concept with_base_table = not_void<typename aod::MetadataTrait<o2::aod::Hash<T::ref.desc_hash>>::metadata::base_table_t>;
 
+template <typename T>
+concept with_expression_pack = not_void<typename aod::MetadataTrait<o2::aod::Hash<T::ref.desc_hash>>::metadata::expression_pack_t>;
+
 template <size_t N1, std::array<TableRef, N1> os1, size_t N2, std::array<TableRef, N2> os2>
 consteval bool is_compatible()
 {

Framework/Core/include/Framework/AnalysisHelpers.h

@@ -38,6 +38,8 @@ constexpr auto tableRef2ConfigParamSpec()
     {"\"\""}};
 }
 
+std::string serializeProjectors(std::vector<framework::expressions::Projector>& projectors);
+
 namespace
 {
 template <soa::with_sources T>
@@ -97,6 +99,26 @@ constexpr auto getCCDBMetadata() -> std::vector<framework::ConfigParamSpec>
 {
   return {};
 }
+
+template <soa::with_expression_pack T>
+constexpr auto getExpressionMetadata() -> std::optional<framework::ConfigParamSpec>
+{
+  using expression_pack_t = T::expression_pack_t;
+
+  auto projectors = []<typename... C>(framework::pack<C...>) -> std::vector<framework::expressions::Projector> {
+    return {C::Projector()...};
+  }(expression_pack_t{});
+
+  auto json = serializeProjectors(projectors);
+  return framework::ConfigParamSpec{"projectors", framework::VariantType::String, json, {"\"\""}};
+}
+
+template <typename T>
+constexpr auto getExpressionMetadata() -> std::optional<framework::ConfigParamSpec>
+{
+  return {};
+}
+
 }  // namespace
 
 template <TableRef R>
@@ -107,6 +129,10 @@ constexpr auto tableRef2InputSpec()
   metadata.insert(metadata.end(), m.begin(), m.end());
   auto ccdbMetadata = getCCDBMetadata<typename o2::aod::MetadataTrait<o2::aod::Hash<R.desc_hash>>::metadata>();
   metadata.insert(metadata.end(), ccdbMetadata.begin(), ccdbMetadata.end());
+  auto p = getExpressionMetadata<typename o2::aod::MetadataTrait<o2::aod::Hash<R.desc_hash>>::metadata>();
+  if (p) {
+    metadata.insert(metadata.end(), p.value());
+  }
 
   return framework::InputSpec{
     o2::aod::label<R>(),

Framework/Core/src/AnalysisHelpers.cxx

@@ -9,6 +9,7 @@
 // granted to it by virtue of its status as an Intergovernmental Organization
 // or submit itself to any jurisdiction.
 #include "Framework/ExpressionHelpers.h"
+#include "Framework/ExpressionJSONHelpers.h"
 
 namespace o2::framework
 {
@@ -26,4 +27,11 @@ void initializePartitionCaches(std::set<uint32_t> const& hashes, std::shared_ptr
     gfilter = framework::expressions::createFilter(schema, framework::expressions::makeCondition(tree));
   }
 }
+
+std::string serializeProjectors(std::vector<framework::expressions::Projector>& projectors)
+{
+  std::stringstream osm;
+  ExpressionJSONHelpers::write(osm, projectors);
+  return osm.str();
+}
 } // namespace o2::framework