[core] Add more debug string types (ray-project#47928)

Followup on ray-project#47893, add more
"blessed container types" to debug string function.

Signed-off-by: dentiny <[email protected]>
Signed-off-by: ujjawal-khare <[email protected]>

src/ray/util/container_util.h

@@ -21,6 +21,7 @@
 #include <set>
 #include <sstream>
 #include <type_traits>
+#include <unordered_map>
 #include <unordered_set>
 #include <vector>
 
@@ -69,6 +70,13 @@ std::ostream &operator<<(std::ostream &os, DebugStringWrapper<T> wrapper) {
   return os << wrapper.obj_;
 }
 
+// TODO(hjiang): Implement debug string for `std::variant`.
+template <>
+inline std::ostream &operator<<(std::ostream &os,
+                                DebugStringWrapper<std::nullopt_t> wrapper) {
+  return os << "(nullopt)";
+}
+
 template <typename... Ts>
 std::ostream &operator<<(std::ostream &os, DebugStringWrapper<std::pair<Ts...>> pair) {
   return os << "(" << debug_string(pair.obj_.first) << ", "
@@ -95,6 +103,10 @@ std::ostream &operator<<(std::ostream &os, DebugStringWrapper<std::tuple<Ts...>>
   return os;
 }
 
+template <typename T, std::size_t N>
+std::ostream &operator<<(std::ostream &os, DebugStringWrapper<std::array<T, N>> c) {
+  return c.StringifyContainer(os);
+}
 template <typename... Ts>
 std::ostream &operator<<(std::ostream &os, DebugStringWrapper<std::vector<Ts...>> c) {
   return c.StringifyContainer(os);
@@ -122,6 +134,19 @@ std::ostream &operator<<(std::ostream &os,
                          DebugStringWrapper<absl::flat_hash_map<Ts...>> c) {
   return c.StringifyContainer(os);
 }
+template <typename... Ts>
+std::ostream &operator<<(std::ostream &os,
+                         DebugStringWrapper<std::unordered_map<Ts...>> c) {
+  return c.StringifyContainer(os);
+}
+
+template <typename T>
+std::ostream &operator<<(std::ostream &os, DebugStringWrapper<std::optional<T>> c) {
+  if (!c.obj_.has_value()) {
+    return os << debug_string(std::nullopt);
+  }
+  return os << debug_string(c.obj_.value());
+}
 
 template <typename C>
 const typename C::mapped_type &map_find_or_die(const C &c,

src/ray/util/tests/container_util_test.cc

@@ -14,11 +14,13 @@
 
 #include "ray/util/container_util.h"
 
+#include <gtest/gtest.h>
+
+#include <optional>
 #include <sstream>
+#include <string>
 #include <tuple>
 
-#include "gtest/gtest.h"
-
 namespace ray {
 
 template <typename T>
@@ -29,8 +31,18 @@ std::string debug_string_to_string(const T &t) {
 }
 
 TEST(ContainerUtilTest, TestDebugString) {
+  // Numerical values.
   ASSERT_EQ(debug_string_to_string(static_cast<int>(2)), "2");
+
+  // String values.
+  ASSERT_EQ(debug_string_to_string(std::string_view{"hello"}), "hello");
+  ASSERT_EQ(debug_string_to_string(std::string{"hello"}), "hello");
+
+  // Non-associative containers.
   ASSERT_EQ(debug_string_to_string(std::vector<int>{1, 2}), "[1, 2]");
+  ASSERT_EQ(debug_string_to_string(std::array<int, 3>{1, 2, 3}), "[1, 2, 3]");
+
+  // Associative containers.
   ASSERT_EQ(debug_string_to_string(std::set<int>{1, 2}), "[1, 2]");
   ASSERT_EQ(debug_string_to_string(std::unordered_set<int>{2}), "[2]");
   ASSERT_EQ(debug_string_to_string(absl::flat_hash_set<int>{1}), "[1]");
@@ -54,6 +66,11 @@ TEST(ContainerUtilTest, TestDebugString) {
   ASSERT_EQ(debug_string_to_string(std::pair<int, std::string>{3, "value"}),
             "(3, value)");
 
+  // Optional.
+  ASSERT_EQ(debug_string_to_string(std::nullopt), "(nullopt)");
+  ASSERT_EQ(debug_string_to_string(std::optional<std::string>{}), "(nullopt)");
+  ASSERT_EQ(debug_string_to_string(std::optional<std::string>{"hello"}), "hello");
+
   // Composable: tuples of pairs of maps and vectors.
   ASSERT_EQ(debug_string_to_string(
                 std::tuple<std::pair<int, std::vector<int>>, std::map<int, int>>{