feat(data-model): add EventHeader for per-event weight and provenance

CMakeLists.txt

@@ -16,6 +16,7 @@ target_sources(
             TYPE HEADERS
             BASE_DIRS include
             FILES
+                include/SHiP/EventHeader.hpp
                 include/SHiP/MCParticle.hpp
                 include/SHiP/SimHit.hpp
                 include/SHiP/SimParticle.hpp
@@ -43,6 +44,7 @@ target_link_libraries(SHiPUnits INTERFACE mp-units::mp-units)
 
 root_generate_dictionary(
   G__SHiPDataModel
+  SHiP/EventHeader.hpp
   SHiP/MCParticle.hpp
   SHiP/SimHit.hpp
   SHiP/SimParticle.hpp

README.md

@@ -10,6 +10,7 @@ An [automatic class reference](https://shipsoft.github.io/data-model/) is built
 
 | Header | Class | Category |
 |--------|-------|----------|
+| `SHiP/EventHeader.hpp` | `SHiP::EventHeader` | Event metadata |
 | `SHiP/MCParticle.hpp` | `SHiP::MCParticle` | MC / generation |
 | `SHiP/SimHit.hpp` | `SHiP::SimHit` | Simulation |
 | `SHiP/SimParticle.hpp` | `SHiP::SimParticle` | Simulation |

include/SHiP/EventHeader.hpp

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <cstdint>
+
+namespace SHiP {
+
+/// Per-event metadata — one record per event
+struct EventHeader {
+  double weight{1.0};              ///< Event weight (e.g. P_DIS / nReplicas)
+  std::int64_t parentEventId{-1};  ///< Originating event id, e.g. the muon
+                                   ///< event that seeded this replica (-1 =
+                                   ///< none). Event-level provenance, distinct
+                                   ///< from MCParticle::motherId which links
+                                   ///< particles within an event.
+};
+
+}  // namespace SHiP

include/SHiP/LinkDef.h

@@ -3,6 +3,9 @@
 #pragma link off all classes;
 #pragma link off all functions;
 
+// Event metadata
+#pragma link C++ class SHiP::EventHeader+;
+
 // MC / generation
 #pragma link C++ class SHiP::MCParticle+;
 #pragma link C++ class std::vector<SHiP::MCParticle>+;

tests/test_rntuple_io.cpp

@@ -11,6 +11,7 @@
 #include "ROOT/RNTupleModel.hxx"
 #include "ROOT/RNTupleReader.hxx"
 #include "ROOT/RNTupleWriter.hxx"
+#include "SHiP/EventHeader.hpp"
 #include "SHiP/MCParticle.hpp"
 #include "SHiP/RecParticle.hpp"
 #include "SHiP/SimHit.hpp"
@@ -25,6 +26,7 @@ constexpr char const* kFileName = "test_rntuple_io_tmp.root";
 
 bool writeFile() {
   auto model = ROOT::RNTupleModel::Create();
+  auto eventHeader = model->MakeField<SHiP::EventHeader>("eventHeader");
   auto mcParticles =
       model->MakeField<std::vector<SHiP::MCParticle>>("mcParticles");
   auto simHits = model->MakeField<std::vector<SHiP::SimHit>>("simHits");
@@ -41,6 +43,7 @@ bool writeFile() {
     return false;
   }
   for (int entry = 0; entry < kEntries; ++entry) {
+    *eventHeader = SHiP::test::makeEventHeader(entry);
     *mcParticles = SHiP::test::makeMCParticles(entry);
     *simHits = SHiP::test::makeSimHits(entry);
     *simParticles = SHiP::test::makeSimParticles(entry);
@@ -64,6 +67,7 @@ bool readAndCompare() {
   }
 
   auto const& entry = reader->GetModel().GetDefaultEntry();
+  auto eventHeader = entry.GetPtr<SHiP::EventHeader>("eventHeader");
   auto mcParticles = entry.GetPtr<std::vector<SHiP::MCParticle>>("mcParticles");
   auto simHits = entry.GetPtr<std::vector<SHiP::SimHit>>("simHits");
   auto simParticles =
@@ -76,6 +80,8 @@ bool readAndCompare() {
   for (int i = 0; i < kEntries; ++i) {
     reader->LoadEntry(i);
     std::string const suffix = " (entry " + std::to_string(i) + ")";
+    ok &= SHiP::test::check("EventHeader round-trip" + suffix,
+                            SHiP::test::makeEventHeader(i), *eventHeader);
     ok &= SHiP::test::check("MCParticle round-trip" + suffix,
                             SHiP::test::makeMCParticles(i), *mcParticles);
     ok &= SHiP::test::check("SimHit round-trip" + suffix,

tests/test_ttree_io.cpp

@@ -11,6 +11,7 @@
 #include <string>
 #include <vector>
 
+#include "SHiP/EventHeader.hpp"
 #include "SHiP/MCParticle.hpp"
 #include "SHiP/RecParticle.hpp"
 #include "SHiP/SimHit.hpp"
@@ -26,10 +27,10 @@ constexpr char const* kFileName = "test_ttree_io_tmp.root";
 bool checkDictionaries() {
   bool ok = true;
   for (auto const* name :
-       {"SHiP::MCParticle", "SHiP::SimHit", "SHiP::SimParticle",
-        "SHiP::SimResult", "SHiP::RecParticle", "std::vector<SHiP::MCParticle>",
-        "std::vector<SHiP::SimHit>", "std::vector<SHiP::SimParticle>",
-        "std::vector<SHiP::RecParticle>"}) {
+       {"SHiP::EventHeader", "SHiP::MCParticle", "SHiP::SimHit",
+        "SHiP::SimParticle", "SHiP::SimResult", "SHiP::RecParticle",
+        "std::vector<SHiP::MCParticle>", "std::vector<SHiP::SimHit>",
+        "std::vector<SHiP::SimParticle>", "std::vector<SHiP::RecParticle>"}) {
     if (TClass::GetClass(name) == nullptr) {
       std::cout << "dictionary for " << name
                 << ": FAIL (TClass::GetClass is null)\n";
@@ -49,19 +50,22 @@ bool writeFile() {
   }
   TTree tree("events", "SHiP data model I/O test");
 
+  SHiP::EventHeader eventHeader;
   std::vector<SHiP::MCParticle> mcParticles;
   std::vector<SHiP::SimHit> simHits;
   std::vector<SHiP::SimParticle> simParticles;
   std::vector<SHiP::RecParticle> recParticles;
   SHiP::SimResult simResult;
 
+  tree.Branch("eventHeader", &eventHeader);
   tree.Branch("mcParticles", &mcParticles);
   tree.Branch("simHits", &simHits);
   tree.Branch("simParticles", &simParticles);
   tree.Branch("recParticles", &recParticles);
   tree.Branch("simResult", &simResult);
 
   for (int entry = 0; entry < kEntries; ++entry) {
+    eventHeader = SHiP::test::makeEventHeader(entry);
     mcParticles = SHiP::test::makeMCParticles(entry);
     simHits = SHiP::test::makeSimHits(entry);
     simParticles = SHiP::test::makeSimParticles(entry);
@@ -90,12 +94,14 @@ bool readAndCompare() {
     return false;
   }
 
+  auto* eventHeader = new SHiP::EventHeader();
   auto* mcParticles = new std::vector<SHiP::MCParticle>();
   auto* simHits = new std::vector<SHiP::SimHit>();
   auto* simParticles = new std::vector<SHiP::SimParticle>();
   auto* recParticles = new std::vector<SHiP::RecParticle>();
   auto* simResult = new SHiP::SimResult();
 
+  tree->SetBranchAddress("eventHeader", &eventHeader);
   tree->SetBranchAddress("mcParticles", &mcParticles);
   tree->SetBranchAddress("simHits", &simHits);
   tree->SetBranchAddress("simParticles", &simParticles);
@@ -106,6 +112,8 @@ bool readAndCompare() {
   for (int entry = 0; entry < kEntries; ++entry) {
     tree->GetEntry(entry);
     std::string const suffix = " (entry " + std::to_string(entry) + ")";
+    ok &= SHiP::test::check("EventHeader round-trip" + suffix,
+                            SHiP::test::makeEventHeader(entry), *eventHeader);
     ok &= SHiP::test::check("MCParticle round-trip" + suffix,
                             SHiP::test::makeMCParticles(entry), *mcParticles);
     ok &= SHiP::test::check("SimHit round-trip" + suffix,
@@ -119,6 +127,7 @@ bool readAndCompare() {
   }
 
   tree->ResetBranchAddresses();
+  delete eventHeader;
   delete mcParticles;
   delete simHits;
   delete simParticles;

tests/test_utils.hpp

@@ -5,6 +5,7 @@
 #include <string>
 #include <vector>
 
+#include "SHiP/EventHeader.hpp"
 #include "SHiP/MCParticle.hpp"
 #include "SHiP/RecParticle.hpp"
 #include "SHiP/SimHit.hpp"
@@ -13,6 +14,14 @@
 
 namespace SHiP::test {
 
+/// Build an EventHeader with distinctive non-default values in every member.
+inline EventHeader makeEventHeader(int offset) {
+  EventHeader h;
+  h.weight = 0.125 + offset;
+  h.parentEventId = 7000 + offset;
+  return h;
+}
+
 /// Build MCParticles with distinctive non-default values in every member.
 inline std::vector<MCParticle> makeMCParticles(int offset) {
   std::vector<MCParticle> v;
@@ -84,6 +93,10 @@ inline SimResult makeSimResult(int offset) {
           .particles = makeSimParticles(offset + 5)};
 }
 
+inline bool equal(EventHeader const& a, EventHeader const& b) {
+  return a.weight == b.weight && a.parentEventId == b.parentEventId;
+}
+
 inline bool equal(MCParticle const& a, MCParticle const& b) {
   return a.pdgCode == b.pdgCode && a.vertex == b.vertex &&
          a.momentum == b.momentum && a.energy == b.energy && a.time == b.time &&