[core] Implement a universal printer

src/ray/util/BUILD

@@ -183,6 +183,10 @@ ray_cc_library(
 ray_cc_library(
     name = "type_traits",
     hdrs = ["type_traits.h"],
+    deps = [
+        "@com_google_absl//absl/meta:type_traits",
+        "@com_google_absl//absl/strings:str_format",
+    ],
 )
 
 ray_cc_library(
@@ -373,3 +377,11 @@ ray_cc_library(
         ":logging",
     ],
 )
+
+ray_cc_library(
+    name = "visitor",
+    hdrs = ["visitor.h"],
+    deps = [
+        "@com_google_absl//absl/meta:type_traits",
+    ],
+)

src/ray/util/strings/BUILD

@@ -0,0 +1,156 @@
+load("//bazel:ray.bzl", "ray_cc_library", "ray_cc_test")
+
+package(default_visibility = ["//visibility:public"])
+
+ray_cc_library(
+    name = "type_printer",
+    hdrs = ["type_printer.h"],
+    deps = [
+        ":get_type_name",
+        "@boost//:core",
+    ],
+)
+
+ray_cc_library(
+    name = "std_printer",
+    hdrs = ["std_printer.h"],
+    deps = [
+        ":ostream_printer",
+    ],
+)
+
+ray_cc_test(
+    name = "std_printer_test",
+    srcs = ["std_printer_test.cc"],
+    tags = ["team:core"],
+    deps = [
+        ":std_printer",
+        "@com_google_absl//absl/strings:str_format",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+ray_cc_library(
+    name = "debug_string_printer",
+    hdrs = ["debug_string_printer.h"],
+)
+
+ray_cc_test(
+    name = "debug_string_printer_test",
+    srcs = ["debug_string_printer_test.cc"],
+    tags = ["team:core"],
+    deps = [
+        ":debug_string_printer",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+ray_cc_library(
+    name = "absl_stringify_printer",
+    hdrs = ["absl_stringify_printer.h"],
+    deps = [
+        "@com_google_absl//absl/strings",
+    ],
+)
+
+ray_cc_test(
+    name = "absl_stringify_printer_test",
+    srcs = ["absl_stringify_printer_test.cc"],
+    tags = ["team:core"],
+    deps = [
+        ":absl_stringify_printer",
+        "@com_google_absl//absl/strings:str_format",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+ray_cc_library(
+    name = "container_printer",
+    hdrs = ["container_printer.h"],
+    deps = [
+        ":ostream_printer",
+        "//src/ray/util:type_traits",
+    ],
+)
+
+ray_cc_test(
+    name = "container_printer_test",
+    srcs = ["container_printer_test.cc"],
+    tags = ["team:core"],
+    deps = [
+        ":container_printer",
+        "//src/ray/util:type_traits",
+        "//src/ray/util:visitor",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+ray_cc_library(
+    name = "ostream_printer",
+    hdrs = ["ostream_printer.h"],
+)
+
+ray_cc_test(
+    name = "ostream_printer_test",
+    srcs = ["ostream_printer_test.cc"],
+    tags = ["team:core"],
+    deps = [
+        ":ostream_printer",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+ray_cc_library(
+    name = "enum_printer",
+    hdrs = ["enum_printer.h"],
+)
+
+ray_cc_test(
+    name = "enum_printer_test",
+    srcs = ["enum_printer_test.cc"],
+    tags = ["team:core"],
+    deps = [
+        ":enum_printer",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+ray_cc_library(
+    name = "debug_printer",
+    hdrs = ["debug_printer.h"],
+    deps = [
+        ":absl_stringify_printer",
+        ":container_printer",
+        ":debug_string_printer",
+        ":enum_printer",
+        ":ostream_printer",
+        ":std_printer",
+        ":type_printer",
+        "//src/ray/util:visitor",
+    ],
+)
+
+ray_cc_test(
+    name = "debug_printer_test",
+    srcs = ["debug_printer_test.cc"],
+    tags = ["team:core"],
+    deps = [
+        ":debug_printer",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+ray_cc_library(
+    name = "get_type_name",
+    hdrs = ["get_type_name.h"],
+)
+
+ray_cc_test(
+    name = "get_type_name_test",
+    srcs = ["get_type_name_test.cc"],
+    tags = ["team:core"],
+    deps = [
+        ":get_type_name",
+        "@com_google_googletest//:gtest_main",
+    ],
+)

src/ray/util/strings/absl_stringify_printer.h

@@ -0,0 +1,47 @@
+// Copyright 2025 The Ray Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//  http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Printer for types which defines `AbslStringify`.
+
+#pragma once
+
+#include <iostream>
+#include <type_traits>
+
+#include "absl/strings/str_cat.h"
+
+namespace ray {
+
+// TODO(hjiang): Later version of abseil contains abseil string defined trait.
+template <typename T, typename = void, typename = void>
+struct is_stringifyable : std::false_type {};
+
+template <typename T, typename SinkType>
+struct is_stringifyable<T,
+                        SinkType,
+                        std::void_t<decltype(AbslStringify(std::declval<SinkType &>(),
+                                                           std::declval<const T &>()))>>
+    : std::true_type {};
+
+template <typename T>
+inline constexpr bool is_stringifyable_v = is_stringifyable<T, std::ostream>::value;
+
+struct AbslStringifyPrinter {
+  template <typename T, std::enable_if_t<is_stringifyable_v<T>, int> = 0>
+  void operator()(std::ostream &os, const T &obj) const {
+    os << absl::StrCat(obj);
+  }
+};
+
+}  // namespace ray

src/ray/util/strings/absl_stringify_printer_test.cc

@@ -0,0 +1,47 @@
+// Copyright 2025 The Ray Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//  http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "ray/util/strings/absl_stringify_printer.h"
+
+#include <gtest/gtest.h>
+
+#include "absl/strings/str_format.h"
+
+namespace ray {
+
+namespace {
+
+struct Point {
+  template <typename Sink>
+  friend void AbslStringify(Sink &sink, const Point &p) {
+    absl::Format(&sink, "(%d, %d)", p.x, p.y);
+  }
+
+  int x;
+  int y;
+};
+
+TEST(AbslStringifyTest, BasicTest) {
+  Point point;
+  point.x = 10;
+  point.y = 20;
+
+  std::stringstream ss;
+  AbslStringifyPrinter{}(ss, point);
+  EXPECT_EQ(ss.str(), "(10, 20)");
+}
+
+}  // namespace
+
+}  // namespace ray