Add CEL enum support

Introduces the `EnumValue`, which behaves like an `IntValue`, but keeps track of the enum name, so that it can be printed using `string.format()`.

PiperOrigin-RevId: 717454914

Author: CEL Dev Team

bazel/deps.bzl

@@ -150,6 +150,8 @@ def cel_spec_deps():
         urls = ["https://github.com/google/cel-spec/archive/" + CEL_SPEC_GIT_SHA + ".zip"],
     )
 
+_ICU4C_VERSION_MAJOR = "76"
+_ICU4C_VERSION_MINOR = "1"
 _ICU4C_BUILD = """
 load("@rules_foreign_cc//foreign_cc:configure.bzl", "configure_make")
 
@@ -161,9 +163,9 @@ filegroup(
 
 config_setting(
     name = "dbg",
-    values = {
+    values = {{
         "compilation_mode": "dbg",
-    },
+    }},
     visibility = ["//visibility:private"],
 )
 
@@ -178,16 +180,24 @@ configure_make(
         "--disable-icuio",
         "--disable-layoutex",
         "--disable-icu-config",
-    ] + select({
+    ] + select({{
         ":dbg": ["--enable-debug"],
         "//conditions:default": [],
-    }),
+    }}),
     lib_source = ":all",
     out_shared_libs = [
         "libicudata.so",
+        "libicudata.so.{version_major}",
+        "libicudata.so.{version_major}.{version_minor}",
         "libicui18n.so",
+        "libicui18n.so.{version_major}",
+        "libicui18n.so.{version_major}.{version_minor}",
         "libicutu.so",
+        "libicutu.so.{version_major}",
+        "libicutu.so.{version_major}.{version_minor}",
         "libicuuc.so",
+        "libicuuc.so.{version_major}",
+        "libicuuc.so.{version_major}.{version_minor}",
     ],
     out_static_libs = [
         "libicudata.a",
@@ -198,7 +208,7 @@ configure_make(
     args = ["-j 8"],
     visibility = ["//visibility:public"],
 )
-"""
+""".format(version_major = _ICU4C_VERSION_MAJOR, version_minor = _ICU4C_VERSION_MINOR)
 
 def cel_cpp_extensions_deps():
     http_archive(
@@ -210,7 +220,7 @@ def cel_cpp_extensions_deps():
     http_archive(
         name = "icu4c",
         sha256 = "dfacb46bfe4747410472ce3e1144bf28a102feeaa4e3875bac9b4c6cf30f4f3e",
-        url = "https://github.com/unicode-org/icu/releases/download/release-76-1/icu4c-76_1-src.tgz",
+        url = "https://github.com/unicode-org/icu/releases/download/release-{version_major}-{version_minor}/icu4c-{version_major}_{version_minor}-src.tgz".format(version_major = _ICU4C_VERSION_MAJOR, version_minor = _ICU4C_VERSION_MINOR),
         strip_prefix = "icu",
         patch_cmds = [
             "rm -f source/common/BUILD.bazel",

common/BUILD

@@ -637,7 +637,6 @@ cc_library(
         "//internal:message_equality",
         "//internal:number",
         "//internal:protobuf_runtime_version",
-        "//internal:serialize",
         "//internal:status_macros",
         "//internal:strings",
         "//internal:time",

common/value.cc

@@ -63,7 +63,7 @@
 namespace cel {
 namespace {
 
-static constexpr std::array<ValueKind, 25> kValueToKindArray = {
+static constexpr std::array kValueToKindArray = {
     ValueKind::kError,     ValueKind::kBool,     ValueKind::kBytes,
     ValueKind::kDouble,    ValueKind::kDuration, ValueKind::kError,
     ValueKind::kInt,       ValueKind::kList,     ValueKind::kList,
@@ -72,7 +72,7 @@ static constexpr std::array<ValueKind, 25> kValueToKindArray = {
     ValueKind::kNull,      ValueKind::kOpaque,   ValueKind::kString,
     ValueKind::kStruct,    ValueKind::kStruct,   ValueKind::kStruct,
     ValueKind::kTimestamp, ValueKind::kType,     ValueKind::kUint,
-    ValueKind::kUnknown};
+    ValueKind::kUnknown,   ValueKind::kInt};
 
 static_assert(kValueToKindArray.size() ==
                   absl::variant_size<common_internal::ValueVariant>(),
@@ -750,17 +750,20 @@ namespace {
 Value NonNullEnumValue(
     absl::Nonnull<const google::protobuf::EnumValueDescriptor*> value) {
   ABSL_DCHECK(value != nullptr);
-  return IntValue(value->number());
+  return EnumValue(value);
 }
 
 Value NonNullEnumValue(absl::Nonnull<const google::protobuf::EnumDescriptor*> type,
                        int32_t number) {
   ABSL_DCHECK(type != nullptr);
-  if (type->is_closed()) {
-    if (ABSL_PREDICT_FALSE(type->FindValueByNumber(number) == nullptr)) {
-      return ErrorValue(absl::InvalidArgumentError(absl::StrCat(
-          "closed enum has no such value: ", type->full_name(), ".", number)));
-    }
+  const google::protobuf::EnumValueDescriptor* enum_value =
+      type->FindValueByNumber(number);
+  if (type->is_closed() && ABSL_PREDICT_FALSE(enum_value == nullptr)) {
+    return ErrorValue(absl::InvalidArgumentError(absl::StrCat(
+        "closed enum has no such value: ", type->full_name(), ".", number)));
+  }
+  if (enum_value != nullptr) {
+    return EnumValue(enum_value);
   }
   return IntValue(number);
 }
@@ -1943,6 +1946,18 @@ absl::optional<IntValue> Value::AsInt() const {
       alternative != nullptr) {
     return *alternative;
   }
+  if (const auto* alternative = absl::get_if<EnumValue>(&variant_);
+      alternative != nullptr) {
+    return IntValue(alternative->NativeValue());
+  }
+  return absl::nullopt;
+}
+
+absl::optional<EnumValue> Value::AsEnum() const {
+  if (const auto* alternative = absl::get_if<EnumValue>(&variant_);
+      alternative != nullptr) {
+    return *alternative;
+  }
   return absl::nullopt;
 }
 
@@ -2350,18 +2365,31 @@ ErrorValue Value::GetError() && {
   return absl::get<ErrorValue>(std::move(variant_));
 }
 
-IntValue Value::GetInt() const {
-  ABSL_DCHECK(IsInt()) << *this;
-  return absl::get<IntValue>(variant_);
-}
-
 #ifdef ABSL_HAVE_EXCEPTIONS
 #define CEL_VALUE_THROW_BAD_VARIANT_ACCESS() throw absl::bad_variant_access()
 #else
 #define CEL_VALUE_THROW_BAD_VARIANT_ACCESS() \
   ABSL_LOG(FATAL) << absl::bad_variant_access().what() /* Crash OK */
 #endif
 
+IntValue Value::GetInt() const {
+  ABSL_DCHECK(IsInt()) << *this;
+  if (const auto* alternative = absl::get_if<IntValue>(&variant_);
+      alternative != nullptr) {
+    return *alternative;
+  }
+  if (const auto* alternative = absl::get_if<EnumValue>(&variant_);
+      alternative != nullptr) {
+    return IntValue(alternative->NativeValue());
+  }
+  CEL_VALUE_THROW_BAD_VARIANT_ACCESS();
+}
+
+EnumValue Value::GetEnum() const {
+  ABSL_DCHECK(IsEnum()) << *this;
+  return absl::get<EnumValue>(variant_);
+}
+
 ListValue Value::GetList() const& {
   ABSL_DCHECK(IsList()) << *this;
   if (const auto* alternative =

common/value.h

@@ -501,7 +501,13 @@ class Value final {
   bool IsError() const { return absl::holds_alternative<ErrorValue>(variant_); }
 
   // Returns `true` if this value is an instance of an int value.
-  bool IsInt() const { return absl::holds_alternative<IntValue>(variant_); }
+  bool IsInt() const {
+    return absl::holds_alternative<IntValue>(variant_) ||
+           absl::holds_alternative<EnumValue>(variant_);
+  }
+
+  // Returns `true` if this value is an instance of an enum value.
+  bool IsEnum() const { return absl::holds_alternative<EnumValue>(variant_); }
 
   // Returns `true` if this value is an instance of a list value.
   bool IsList() const {
@@ -671,6 +677,13 @@ class Value final {
     return IsInt();
   }
 
+  // Convenience method for use with template metaprogramming. See
+  // `IsEnum()`.
+  template <typename T>
+  std::enable_if_t<std::is_same_v<EnumValue, T>, bool> Is() const {
+    return IsEnum();
+  }
+
   // Convenience method for use with template metaprogramming. See
   // `IsList()`.
   template <typename T>
@@ -856,6 +869,11 @@ class Value final {
   // int value. Otherwise an empty optional is returned.
   absl::optional<IntValue> AsInt() const;
 
+  // Performs a checked cast from a value to an enum value,
+  // returning a non-empty optional with either a value or reference to the
+  // enum value. Otherwise an empty optional is returned.
+  absl::optional<EnumValue> AsEnum() const;
+
   // Performs a checked cast from a value to a list value,
   // returning a non-empty optional with either a value or reference to the
   // list value. Otherwise an empty optional is returned.
@@ -1791,6 +1809,11 @@ class Value final {
   // false, calling this method is undefined behavior.
   IntValue GetInt() const;
 
+  // Performs an unchecked cast from a value to an int value. In
+  // debug builds a best effort is made to crash. If `IsInt()` would return
+  // false, calling this method is undefined behavior.
+  EnumValue GetEnum() const;
+
   // Performs an unchecked cast from a value to a list value. In
   // debug builds a best effort is made to crash. If `IsList()` would return
   // false, calling this method is undefined behavior.
@@ -2104,6 +2127,25 @@ class Value final {
     return GetInt();
   }
 
+  // Convenience method for use with template metaprogramming. See
+  // `GetEnum()`.
+  template <typename T>
+  std::enable_if_t<std::is_same_v<EnumValue, T>, EnumValue> Get() & {
+    return GetEnum();
+  }
+  template <typename T>
+  std::enable_if_t<std::is_same_v<EnumValue, T>, EnumValue> Get() const& {
+    return GetEnum();
+  }
+  template <typename T>
+  std::enable_if_t<std::is_same_v<EnumValue, T>, EnumValue> Get() && {
+    return GetEnum();
+  }
+  template <typename T>
+  std::enable_if_t<std::is_same_v<EnumValue, T>, EnumValue> Get() const&& {
+    return GetEnum();
+  }
+
   // Convenience method for use with template metaprogramming. See
   // `GetList()`.
   template <typename T>

common/values/enum_value.cc

@@ -0,0 +1,26 @@
+// Copyright 2023 Google LLC
+//
+// 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
+//
+//     https://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 "google/protobuf/wrappers.pb.h"
+#include "absl/status/statusor.h"
+#include "common/value.h"
+
+namespace cel {
+
+absl::StatusOr<Value> EnumValue::Equal(ValueManager& value_manager,
+                                       const Value& other) const {
+  return IntValue(NativeValue()).Equal(value_manager, other);
+}
+
+}  // namespace cel