Fix reading of objects with custom streamer stored in TTree branch

.github/workflows/jsroot-ci.yml

@@ -70,6 +70,7 @@ jobs:
           node demo/node/rntuple_bitset_test.js demo/node/rntuple_bitset_test.root
           node demo/node/tree_int64_test.js demo/node/tree_int64_test.root
           node demo/node/tree_lzma_test.js demo/node/tree_lzma_test.root
+          node demo/node/tree_tobject_test.js demo/node/tree_tobject_test.root
           node demo/node/tree_draw_range.js demo/node/rntuple_test.root
           node demo/node/rntuple_test32.js demo/node/rntuple_test32.root demo/node/rntuple_test32.json
 
@@ -192,6 +193,7 @@ jobs:
           node demo/node/rntuple_bitset_test.js demo/node/rntuple_bitset_test.root
           node demo/node/tree_int64_test.js demo/node/tree_int64_test.root
           node demo/node/tree_lzma_test.js demo/node/tree_lzma_test.root
+          node demo/node/tree_tobject_test.js demo/node/tree_tobject_test.root
           node demo/node/tree_draw_range.js demo/node/rntuple_test.root
           node demo/node/rntuple_test32.js demo/node/rntuple_test32.root demo/node/rntuple_test32.json
 
@@ -249,6 +251,7 @@ jobs:
           node demo/node/rntuple_bitset_test.js demo/node/rntuple_bitset_test.root
           node demo/node/tree_int64_test.js demo/node/tree_int64_test.root
           node demo/node/tree_lzma_test.js demo/node/tree_lzma_test.root
+          node demo/node/tree_tobject_test.js demo/node/tree_tobject_test.root
           node demo/node/tree_draw_range.js demo/node/rntuple_test.root
           node demo/node/rntuple_test32.js demo/node/rntuple_test32.root demo/node/rntuple_test32.json
 

demo/node/tree_tobject_test.cxx

@@ -0,0 +1,34 @@
+// macro to create tree_tobject_test.root used by tree_tobject_test.js
+// root -l -b -q tree_tobject_test.cxx
+
+#include <TFile.h>
+#include <TTree.h>
+#include <TLorentzVector.h>
+#include <TVector3.h>
+#include <TGraph.h>
+#include <TDatime.h>
+
+void tree_tobject_test()
+{
+   TFile f("tree_tobject_test.root", "RECREATE");
+
+   TTree t("t", "Objects with custom streamers");
+   TLorentzVector *lv = new TLorentzVector;
+   TVector3 *v3 = new TVector3;
+   TGraph *gr = new TGraph(3);
+   TDatime *dt = new TDatime;
+   // classes with custom streamers are not split by ROOT
+   t.Branch("lv", &lv);
+   t.Branch("v3", &v3);
+   t.Branch("gr", &gr);
+   t.Branch("dt", &dt);
+   for (Int_t i = 0; i < 100; ++i) {
+      lv->SetPxPyPzE(i, 2 * i, 3 * i, 4 * i + 1);
+      v3->SetXYZ(i, -i, 0.5 * i);
+      for (Int_t j = 0; j < 3; ++j)
+         gr->SetPoint(j, j, i + j);
+      dt->Set(2026, 1, 1, 0, 0, i % 60);
+      t.Fill();
+   }
+   t.Write();
+}

demo/node/tree_tobject_test.js

@@ -0,0 +1,65 @@
+import { version, openFile } from 'jsroot';
+import { TSelector, treeProcess } from 'jsroot/tree';
+
+// test reading of objects with custom streamers, file created with tree_tobject_test.cxx
+
+console.log(`JSROOT version ${version}`);
+
+const nentries = 100;
+
+let filename = './tree_tobject_test.root',
+    any_error = false,
+    err_cnt = 0;
+
+if (process?.argv && process.argv[2])
+   filename = process.argv[2];
+
+function failure(msg) {
+   any_error = true;
+   if (err_cnt++ < 10)
+      console.error(`FAILURE: ${msg}`);
+}
+
+const file = await openFile(filename),
+      tree = await file.readObject('t'),
+      selector = new TSelector();
+
+let cnt = 0;
+
+selector.addBranch('lv');
+selector.addBranch('v3');
+selector.addBranch('gr');
+selector.addBranch('dt');
+
+selector.Process = function() {
+   const i = cnt++, { lv, v3, gr, dt } = this.tgtobj;
+
+   if ((lv?.fP?.fX !== i) || (lv.fP.fY !== 2 * i) || (lv.fP.fZ !== 3 * i) || (lv.fE !== 4 * i + 1))
+      failure(`entry ${i} wrong TLorentzVector ${JSON.stringify(lv)}`);
+
+   if ((v3?.fX !== i) || (v3.fY !== -i) || (v3.fZ !== 0.5 * i))
+      failure(`entry ${i} wrong TVector3 ${JSON.stringify(v3)}`);
+
+   if ((gr?.fNpoints !== 3) || (gr.fX?.[2] !== 2) || (gr.fY?.[2] !== i + 2))
+      failure(`entry ${i} wrong TGraph npoints ${gr?.fNpoints} x ${gr?.fX?.[2]} y ${gr?.fY?.[2]}`);
+
+   // TDatime has no version header, seconds are stored in lower 6 bits
+   const sec = Number.isInteger(dt?.fDatime) ? dt.fDatime & 0x3f : -1;
+   if (sec !== i % 60)
+      failure(`entry ${i} wrong TDatime seconds ${sec}`);
+};
+
+try {
+   await treeProcess(tree, selector);
+} catch (err) {
+   failure(`exception when reading tree: ${err.message}`);
+}
+
+if (cnt !== nentries)
+   failure(`expected ${nentries} tree entries but got ${cnt}`);
+
+if (any_error) {
+   console.error('\nFAILURE when reading objects with custom streamers');
+   process.exit(1);
+} else
+   console.log(`OK: tree with ${cnt} entries\n\nTest OK`);

modules/tree.mjs

@@ -2142,6 +2142,12 @@ async function treeProcess(tree, selector, args) {
                      obj[this.name] = res;
                   }
                };
+               // object written by custom streamer of the class, it has version and bytecount
+               if (branch.fType === -1) {
+                  member.func = function(buf, obj) {
+                     obj[this.name] = buf.classStreamer({}, this.typename);
+                  };
+               }
             }
          }