From 59e5f366fe18c54f8d9e4f26742c02f6e7a9164a Mon Sep 17 00:00:00 2001
From: lani_karrot <lani@daangn.com>
Date: Wed, 7 Jan 2026 19:24:49 +0900
Subject: [PATCH] fix: rejecting inf as value

---
 tdigest/include/tdigest_impl.hpp |  5 +++
 tdigest/test/tdigest_test.cpp    | 53 ++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/tdigest/include/tdigest_impl.hpp b/tdigest/include/tdigest_impl.hpp
index b8fab38d..75f2d9ee 100644
--- a/tdigest/include/tdigest_impl.hpp
+++ b/tdigest/include/tdigest_impl.hpp
@@ -37,6 +37,7 @@ tdigest(false, k, std::numeric_limits<T>::infinity(), -std::numeric_limits<T>::i
 template<typename T, typename A>
 void tdigest<T, A>::update(T value) {
   if (std::isnan(value)) return;
+  if (std::isinf(value)) return;
   if (buffer_.size() == centroids_capacity_ * BUFFER_MULTIPLIER) compress();
   buffer_.push_back(value);
   min_ = std::min(min_, value);
@@ -94,6 +95,7 @@ template<typename T, typename A>
 double tdigest<T, A>::get_rank(T value) const {
   if (is_empty()) throw std::runtime_error("operation is undefined for an empty sketch");
   if (std::isnan(value)) throw std::invalid_argument("operation is undefined for NaN");
+  if (std::isinf(value)) throw std::invalid_argument("operation is undefined for infinity");
   if (value < min_) return 0;
   if (value > max_) return 1;
   // one centroid and value == min_ == max_
@@ -621,6 +623,9 @@ void tdigest<T, A>::check_split_points(const T* values, uint32_t size) {
     if (std::isnan(values[i])) {
       throw std::invalid_argument("Values must not be NaN");
     }
+    if (std::isinf(values[i])) {
+      throw std::invalid_argument("Values must not be infinity");
+    }
     if ((i < (size - 1)) && !(values[i] < values[i + 1])) {
       throw std::invalid_argument("Values must be unique and monotonically increasing");
     }
diff --git a/tdigest/test/tdigest_test.cpp b/tdigest/test/tdigest_test.cpp
index 9f92094d..45c10822 100644
--- a/tdigest/test/tdigest_test.cpp
+++ b/tdigest/test/tdigest_test.cpp
@@ -470,4 +470,57 @@ TEST_CASE("iterate centroids", "[tdigest]") {
   REQUIRE(td.get_total_weight() == total_weight);
 }
 
+TEST_CASE("update rejects positive infinity", "[tdigest]") {
+  tdigest_double td(100);
+  td.update(1.0);
+  td.update(2.0);
+  td.update(std::numeric_limits<double>::infinity());
+  REQUIRE(td.get_total_weight() == 2);
+  REQUIRE(td.get_max_value() == 2.0);
+}
+
+TEST_CASE("update rejects negative infinity", "[tdigest]") {
+  tdigest_double td(100);
+  td.update(1.0);
+  td.update(2.0);
+  td.update(-std::numeric_limits<double>::infinity());
+  REQUIRE(td.get_total_weight() == 2);
+  REQUIRE(td.get_min_value() == 1.0);
+}
+
+TEST_CASE("get_rank rejects positive infinity", "[tdigest]") {
+  tdigest_double td(100);
+  td.update(1.0);
+  td.update(2.0);
+  REQUIRE_THROWS_AS(td.get_rank(std::numeric_limits<double>::infinity()), std::invalid_argument);
+}
+
+TEST_CASE("get_rank rejects negative infinity", "[tdigest]") {
+  tdigest_double td(100);
+  td.update(1.0);
+  td.update(2.0);
+  REQUIRE_THROWS_AS(td.get_rank(-std::numeric_limits<double>::infinity()), std::invalid_argument);
+}
+
+TEST_CASE("get_CDF rejects positive infinity in split points", "[tdigest]") {
+  tdigest_double td(100);
+  for (int i = 0; i < 100; ++i) td.update(i);
+  const double split_points[2] = {50.0, std::numeric_limits<double>::infinity()};
+  REQUIRE_THROWS_AS(td.get_CDF(split_points, 2), std::invalid_argument);
+}
+
+TEST_CASE("get_CDF rejects negative infinity in split points", "[tdigest]") {
+  tdigest_double td(100);
+  for (int i = 0; i < 100; ++i) td.update(i);
+  const double split_points[2] = {-std::numeric_limits<double>::infinity(), 50.0};
+  REQUIRE_THROWS_AS(td.get_CDF(split_points, 2), std::invalid_argument);
+}
+
+TEST_CASE("get_PMF rejects infinity in split points", "[tdigest]") {
+  tdigest_double td(100);
+  for (int i = 0; i < 100; ++i) td.update(i);
+  const double split_points[1] = {std::numeric_limits<double>::infinity()};
+  REQUIRE_THROWS_AS(td.get_PMF(split_points, 1), std::invalid_argument);
+}
+
 } /* namespace datasketches */