From 58ef95409d8b5ae50a5ddf7f9703bc9e3dcb4057 Mon Sep 17 00:00:00 2001
From: silverweed <silverweed14@proton.me>
Date: Fri, 12 Jul 2024 15:56:04 +0200
Subject: [PATCH] wip gather page/columns metadata

---
 src/rntuple.cpp | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/src/rntuple.cpp b/src/rntuple.cpp
index ae3b3ea..a74eab8 100644
--- a/src/rntuple.cpp
+++ b/src/rntuple.cpp
@@ -10,7 +10,7 @@ String8 rntuple_description(Arena *arena, const RNTuple_Data &ntuple)
 }
 
 internal
-void gather_metadata(Arena *arena, RMicroFileReader &reader, const RNTuple_File_Info &info)
+ROOT::Experimental::RNTupleDescriptor create_descriptor(Arena *arena, RMicroFileReader &reader, const RNTuple_File_Info &info)
 {
   using namespace ROOT::Experimental;
   using namespace ROOT::Experimental::Internal;
@@ -58,6 +58,31 @@ void gather_metadata(Arena *arena, RMicroFileReader &reader, const RNTuple_File_
 
     arena_pop_to(scratch.arena, arena_start);
   }
+
+  return descriptor;
+}
+
+internal
+void gather_metadata(Arena *arena, RMicroFileReader &reader, const RNTuple_File_Info &info)
+{
+  using namespace ROOT::Experimental;
+  using namespace ROOT::Experimental::Internal;
+
+  RNTupleDescriptor descriptor = create_descriptor(arena, reader, info);
+
+  // for all clusters ...
+  DescriptorId_t cluster_id = descriptor.FindClusterId(0, 0);
+  while (cluster_id != kInvalidDescriptorId) {
+    const RClusterDescriptor &cluster_desc = descriptor.GetClusterDescriptor(cluster_id);
+    for (const auto &[col_id, col_range] : cluster_desc.GetColumnRangeIterable()) {
+      // TODO gather column metadata
+      // TODO gather page metadata
+      const auto &page_range = cluster_desc.GetPageRange(col_id);
+      for (const auto &page_info : page_range.fPageInfos) {
+        
+      }
+    }
+  }
 }
 
 internal