index builder info and serialization

Author: aalkin

Framework/AnalysisSupport/src/AODReaderHelpers.cxx

@@ -57,6 +57,38 @@ auto make_build(D metadata, InputSpec const& input, ProcessingContext& pc)
                                                                                                         extractOriginals<sources.size(), sources>(pc),
                                                                                                         index_pack_t{});
 }
+
+struct Builder {
+
+};
+
+struct Buildable {
+  std::string binding;
+
+  header::DataOrigin origin;
+  header::DataDescription description;
+  header::DataHeader::SubSpecificationType version;
+
+  Buildable(InputSpec const& spec)
+    : binding{spec.binding}
+  {
+    auto&& [origin_, description_, version_] = DataSpecUtils::asConcreteDataMatcher(spec);
+    origin = origin_;
+    description = description_;
+    version = version_;
+
+    // The following components are needed to build an index table
+    // 1. the labels of the source tables to extract from inputRecord -> extracted from input metadata
+    // 2. the mapping, in the order of the definition of columns, of the
+    //    position in each source table of an index column pointing to the Key
+    //    and the types of index to write (self, single-valued, slice or array)
+    // the mapping has to be created at the point where the type information is available and
+    // put into the input spec metadata as a vector of (type, label, pos)
+
+  }
+
+};
+
 } // namespace
 
 AlgorithmSpec AODReaderHelpers::indexBuilderCallback(ConfigContext const& ctx)

Framework/Core/include/Framework/ASoA.h

@@ -1307,6 +1307,11 @@ concept with_expression_pack = requires {
   typename T::expression_pack_t{};
 };
 
+template <typename T>
+concept with_index_pack = requires {
+  typename T::index_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

@@ -54,6 +54,19 @@ constexpr auto tableRef2Schema()
     {"\"\""}};
 }
 
+enum struct IndexKind : unsigned {
+  IdxSelf = 0,
+  IdxSingle = 1,
+  IdxSlice = 2,
+  IdxArray = 3
+};
+
+struct IndexRecord {
+  std::string label;
+  IndexKind kind;
+  size_t pos;
+};
+
 namespace
 {
 template <soa::with_sources T>
@@ -154,6 +167,20 @@ constexpr auto getExpressionMetadata() -> std::vector<framework::ConfigParamSpec
   return {};
 }
 
+template <soa::with_index_pack T>
+constexpr auto getIndexMetadata() -> std::vector<framework::ConfigParamSpec>
+{
+
+  return {};
+}
+
+template <typename T>
+  requires(!soa::with_index_pack<T>)
+constexpr auto getIndexMetadata() -> std::vector<framework::ConfigParamSpec>
+{
+  return {};
+}
+
 }  // namespace
 
 template <TableRef R>

Framework/Core/include/Framework/IndexBuilderHelpers.h

@@ -11,13 +11,11 @@
 
 #ifndef O2_FRAMEWORK_INDEXBUILDERHELPERS_H_
 #define O2_FRAMEWORK_INDEXBUILDERHELPERS_H_
-#include "arrow/array.h"
 #include <arrow/chunked_array.h>
 #include <arrow/builder.h>
 #include <arrow/memory_pool.h>
 #include <string>
 #include <memory>
-#include <type_traits>
 
 namespace o2::framework
 {

Framework/Core/src/IndexJSONHelpers.cxx

@@ -0,0 +1,24 @@
+// Copyright 2019-2025 CERN and copyright holders of ALICE O2.
+// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+// All rights not expressly granted are reserved.
+//
+// This software is distributed under the terms of the GNU General Public
+// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
+//
+// In applying this license CERN does not waive the privileges and immunities
+// granted to it by virtue of its status as an Intergovernmental Organization
+// or submit itself to any jurisdiction.
+
+#include "IndexJSONHelpers.h"
+
+namespace o2::framework {
+std::vector<o2::soa::IndexRecord> IndexJSONHelpers::read(std::istream& s)
+{
+
+}
+
+void IndexJSONHelpers::write(std::ostream& o, std::vector<o2::soa::IndexRecord>& irs)
+{
+
+}
+}

Framework/Core/src/IndexJSONHelpers.h

@@ -0,0 +1,25 @@
+// Copyright 2019-2025 CERN and copyright holders of ALICE O2.
+// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+// All rights not expressly granted are reserved.
+//
+// This software is distributed under the terms of the GNU General Public
+// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
+//
+// In applying this license CERN does not waive the privileges and immunities
+// granted to it by virtue of its status as an Intergovernmental Organization
+// or submit itself to any jurisdiction.
+#ifndef INDEXJSONHELPERS_H
+#define INDEXJSONHELPERS_H
+
+#include <Framework/AnalysisHelpers.h>
+
+namespace o2::framework
+{
+struct IndexJSONHelpers {
+  static std::vector<o2::soa::IndexRecord> read(std::istream& s);
+  static void write(std::ostream& o, std::vector<o2::soa::IndexRecord>& irs);
+};
+
+} // namespace o2::framework
+
+#endif // INDEXJSONHELPERS_H