From d3b325d02f383eb118a2e94717259a132f9913cf Mon Sep 17 00:00:00 2001
From: fis <jm.yuan@outlook.com>
Date: Tue, 11 Jan 2022 00:35:55 +0800
Subject: [PATCH] Code comments.

---
 src/tree/tree_model.cc | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/tree/tree_model.cc b/src/tree/tree_model.cc
index 2105e599a0a5..d78347381413 100644
--- a/src/tree/tree_model.cc
+++ b/src/tree/tree_model.cc
@@ -893,13 +893,13 @@ void RegTree::Save(dmlc::Stream* fo) const {
     }
   }
 }
-
+// typed array, not boolean
 template <typename JT, typename T>
 std::enable_if_t<!std::is_same<T, Json>::value && !std::is_same<JT, Boolean>::value, T> GetElem(
     std::vector<T> const& arr, size_t i) {
   return arr[i];
 }
-
+// typed array boolean
 template <typename JT, typename T>
 std::enable_if_t<!std::is_same<T, Json>::value && std::is_same<T, uint8_t>::value &&
                      std::is_same<JT, Boolean>::value,
@@ -907,7 +907,7 @@ std::enable_if_t<!std::is_same<T, Json>::value && std::is_same<T, uint8_t>::valu
 GetElem(std::vector<T> const& arr, size_t i) {
   return arr[i] == 1;
 }
-
+// json array
 template <typename JT, typename T>
 std::enable_if_t<
     std::is_same<T, Json>::value,
@@ -966,7 +966,7 @@ void RegTree::LoadCategoricalSplit(Json const& in) {
 
       ++cnt;
       if (cnt == categories_nodes.size()) {
-        last_cat_node = -1;
+        last_cat_node = -1;  // Don't break, we still need to initialize the remaining nodes.
       } else {
         last_cat_node = GetElem<Integer>(categories_nodes, cnt);
       }
@@ -987,8 +987,8 @@ void RegTree::SaveCategoricalSplit(Json* p_out) const {
 
   I64Array categories_segments;
   I64Array categories_sizes;
-  I32Array categories;
-  I32Array categories_nodes;
+  I32Array categories;        // bst_cat_t = int32_t
+  I32Array categories_nodes;  // bst_note_t = int32_t
 
   for (size_t i = 0; i < nodes_.size(); ++i) {
     if (this->split_types_[i] == FeatureType::kCategorical) {