From 34a5563c7d797f2a07eb08b473ba75f5275c2bb9 Mon Sep 17 00:00:00 2001
From: silverweed <giacomo.parolini@cern.ch>
Date: Tue, 17 Jun 2025 11:05:58 +0200
Subject: [PATCH] [ntuple] Add some Internal helpers needed for Attributes

- const version of GetProjectedFieldsOfModel()
- RPageSink::GetUnderlyingDirectory()
---
 tree/ntuple/inc/ROOT/RMiniFile.hxx        | 5 +++++
 tree/ntuple/inc/ROOT/RNTupleModel.hxx     | 2 ++
 tree/ntuple/inc/ROOT/RPageStorage.hxx     | 2 ++
 tree/ntuple/inc/ROOT/RPageStorageFile.hxx | 2 ++
 tree/ntuple/src/RMiniFile.cxx             | 8 ++++++++
 tree/ntuple/src/RNTupleModel.cxx          | 6 ++++++
 6 files changed, 25 insertions(+)

diff --git a/tree/ntuple/inc/ROOT/RMiniFile.hxx b/tree/ntuple/inc/ROOT/RMiniFile.hxx
index 02d07862e9055..6197906abd74c 100644
--- a/tree/ntuple/inc/ROOT/RMiniFile.hxx
+++ b/tree/ntuple/inc/ROOT/RMiniFile.hxx
@@ -33,7 +33,10 @@ class TVirtualStreamerInfo;
 namespace ROOT {
 
 namespace Internal {
+class RNTupleFileWriter;
 class RRawFile;
+
+TDirectory *GetUnderlyingDirectory(ROOT::Internal::RNTupleFileWriter &writer);
 }
 
 class RNTupleWriteOptions;
@@ -104,6 +107,8 @@ A stand-alone version of RNTuple can remove the TFile based writer.
 */
 // clang-format on
 class RNTupleFileWriter {
+   friend TDirectory *GetUnderlyingDirectory(ROOT::Internal::RNTupleFileWriter &writer);
+
 public:
    /// The key length of a blob. It is always a big key (version > 1000) with class name RBlob.
    static constexpr std::size_t kBlobKeyLen = 42;
diff --git a/tree/ntuple/inc/ROOT/RNTupleModel.hxx b/tree/ntuple/inc/ROOT/RNTupleModel.hxx
index 8192cc4d2ca99..4cf0b14272bd4 100644
--- a/tree/ntuple/inc/ROOT/RNTupleModel.hxx
+++ b/tree/ntuple/inc/ROOT/RNTupleModel.hxx
@@ -46,6 +46,7 @@ class RProjectedFields;
 
 ROOT::RFieldZero &GetFieldZeroOfModel(RNTupleModel &model);
 RProjectedFields &GetProjectedFieldsOfModel(RNTupleModel &model);
+const RProjectedFields &GetProjectedFieldsOfModel(const RNTupleModel &model);
 
 // clang-format off
 /**
@@ -139,6 +140,7 @@ that were used for writing and are no longer connected to a page sink.
 class RNTupleModel {
    friend ROOT::RFieldZero &Internal::GetFieldZeroOfModel(RNTupleModel &);
    friend Internal::RProjectedFields &Internal::GetProjectedFieldsOfModel(RNTupleModel &);
+   friend const Internal::RProjectedFields &Internal::GetProjectedFieldsOfModel(const RNTupleModel &);
 
 public:
    /// User-provided function that describes the mapping of existing source fields to projected fields in terms
diff --git a/tree/ntuple/inc/ROOT/RPageStorage.hxx b/tree/ntuple/inc/ROOT/RPageStorage.hxx
index 6fcf41f646128..1e8307a8d9c8c 100644
--- a/tree/ntuple/inc/ROOT/RPageStorage.hxx
+++ b/tree/ntuple/inc/ROOT/RPageStorage.hxx
@@ -313,6 +313,8 @@ public:
 
    virtual ROOT::NTupleSize_t GetNEntries() const = 0;
 
+   virtual TDirectory *GetUnderlyingDirectory() const { return nullptr; }
+
    /// Physically creates the storage container to hold the ntuple (e.g., a keys a TFile or an S3 bucket)
    /// Init() associates column handles to the columns referenced by the model
    void Init(RNTupleModel &model)
diff --git a/tree/ntuple/inc/ROOT/RPageStorageFile.hxx b/tree/ntuple/inc/ROOT/RPageStorageFile.hxx
index b223d008f0c07..6174e221e29de 100644
--- a/tree/ntuple/inc/ROOT/RPageStorageFile.hxx
+++ b/tree/ntuple/inc/ROOT/RPageStorageFile.hxx
@@ -98,6 +98,8 @@ public:
    RPageSinkFile(RPageSinkFile &&) = default;
    RPageSinkFile &operator=(RPageSinkFile &&) = default;
    ~RPageSinkFile() override;
+
+   TDirectory *GetUnderlyingDirectory() const final { return ROOT::Internal::GetUnderlyingDirectory(*fWriter); }
 }; // class RPageSinkFile
 
 // clang-format off
diff --git a/tree/ntuple/src/RMiniFile.cxx b/tree/ntuple/src/RMiniFile.cxx
index 5191d82f449a0..3d154a312e5d3 100644
--- a/tree/ntuple/src/RMiniFile.cxx
+++ b/tree/ntuple/src/RMiniFile.cxx
@@ -1548,3 +1548,11 @@ void ROOT::Internal::RNTupleFileWriter::WriteTFileSkeleton(int defaultCompressio
       fileSimple.Write(&padding, sizeof(padding));
    fileSimple.fKeyOffset = fileSimple.fFilePos;
 }
+
+TDirectory *ROOT::Internal::GetUnderlyingDirectory(ROOT::Internal::RNTupleFileWriter &writer)
+{
+   if (auto *proper = std::get_if<ROOT::Internal::RNTupleFileWriter::RFileProper>(&writer.fFile)) {
+      return proper->fDirectory;
+   }
+   return nullptr;
+}
diff --git a/tree/ntuple/src/RNTupleModel.cxx b/tree/ntuple/src/RNTupleModel.cxx
index 2878866ffb3ef..049762aed0ffc 100644
--- a/tree/ntuple/src/RNTupleModel.cxx
+++ b/tree/ntuple/src/RNTupleModel.cxx
@@ -40,6 +40,12 @@ ROOT::RFieldZero &ROOT::Internal::GetFieldZeroOfModel(ROOT::RNTupleModel &model)
 }
 
 ROOT::Internal::RProjectedFields &ROOT::Internal::GetProjectedFieldsOfModel(ROOT::RNTupleModel &model)
+{
+   return const_cast<ROOT::Internal::RProjectedFields &>(
+      GetProjectedFieldsOfModel(const_cast<const ROOT::RNTupleModel &>(model)));
+}
+
+const ROOT::Internal::RProjectedFields &ROOT::Internal::GetProjectedFieldsOfModel(const ROOT::RNTupleModel &model)
 {
    if (model.IsExpired()) {
       throw RException(R__FAIL("invalid use of expired model"));