Introducin RNTuple

modules/draw.mjs

@@ -135,6 +135,7 @@ drawFuncs = { lst: [
    { name: clTBranchFunc, icon: 'img_leaf_method', draw: () => import_tree().then(h => h.drawTree), opt: ';dump', noinspect: true },
    { name: /^TBranch/, icon: 'img_branch', draw: () => import_tree().then(h => h.drawTree), dflt: 'expand', opt: ';dump', ctrl: 'dump', shift: kInspect, ignore_online: true, always_draw: true },
    { name: /^TLeaf/, icon: 'img_leaf', noexpand: true, draw: () => import_tree().then(h => h.drawTree), opt: ';dump', ctrl: 'dump', ignore_online: true, always_draw: true },
+   { name: 'ROOT::RNTuple', icon: 'img_tree', get_expand: () => import('./rntuple.mjs').then(h => h.tupleHierarchy) },
    { name: clTList, icon: 'img_list', draw: () => import_h().then(h => h.drawList), get_expand: () => import_h().then(h => h.listHierarchy), dflt: 'expand' },
    { name: clTHashList, sameas: clTList },
    { name: clTObjArray, sameas: clTList },

modules/io.mjs

@@ -375,6 +375,11 @@ CustomStreamers = {
       func(buf, obj) { obj.$kind = 'TTree'; obj.$file = buf.fFile; }
    },
 
+   'ROOT::RNTuple': {
+      name: '$file',
+      func(buf, obj) { obj.$kind = 'ROOT::RNTuple'; obj.$file = buf.fFile; }
+   },
+
    RooRealVar(buf, obj) {
       const v = buf.last_read_version;
       buf.classStreamer(obj, 'RooAbsRealLValue');

modules/rntuple.mjs

@@ -0,0 +1,86 @@
+import { R__unzip } from './io.mjs';
+
+
+class RNTupleDescriptorBuilder {
+
+   deserializeHeader(header_blob) {
+      if (!header_blob)
+         return;
+
+      this.xxhash3 = 1234;
+      this.featuresFlags = [];
+      this.name = 'rntuple';
+      this.description = 'description';
+      // this.deserializeSchemaDescription ...
+   }
+
+   deserializeFooter(footer_blob) {
+      if (!footer_blob)
+         return;
+      this.xxhash3 = 1234;
+   }
+
+}
+
+/** @summary Very preliminary function to read header/footer from RNTuple
+  * @private */
+async function readHeaderFooter(tuple) {
+   if (!tuple.$file)
+      return false;
+
+   // request header and footer buffers from the file
+   return tuple.$file.readBuffer([tuple.fSeekHeader, tuple.fNBytesHeader, tuple.fSeekFooter, tuple.fNBytesFooter]).then(blobs => {
+      if (blobs?.length !== 2)
+         return false;
+
+      // unzip both buffers
+      return Promise.all([
+         R__unzip(blobs[0], tuple.fLenHeader),
+         R__unzip(blobs[1], tuple.fLenFooter)
+      ]).then(unzip_blobs => {
+         const header_blob = unzip_blobs[0],
+               footer_blob = unzip_blobs[1];
+         if (!header_blob || !footer_blob)
+            return false;
+
+         // create builder description and decode it - dummy for the moment
+
+         tuple.builder = new RNTupleDescriptorBuilder;
+
+         tuple.builder.deserializeHeader(header_blob);
+
+         tuple.builder.deserializeFooter(footer_blob);
+
+         return true;
+      });
+   });
+}
+
+
+/** @summary Create hierarchy of ROOT::RNTuple object
+  * @desc Used by hierarchy painter to explore sub-elements
+  * @private */
+async function tupleHierarchy(tuple_node, tuple) {
+   tuple_node._childs = [];
+   // tuple_node._tuple = tuple;  // set reference, will be used later by RNTuple::Draw
+
+   return readHeaderFooter(tuple).then(res => {
+      if (!res)
+         return res;
+
+      // just show which objects belongs to hierarchy
+      // one need to fill list of items from tuple.builder ... object
+      for (let k = 0; k < 3; ++k) {
+         tuple_node._childs.push({
+            _name: `dummy${k}`,
+            _kind: 'ROOT::SomeBranchName',
+            _title: `Any title for dummy${k}`,
+            _obj: null
+         });
+      }
+
+      return true;
+   });
+}
+
+export { tupleHierarchy };