[cel-types] Add Protobuf definitions and codecs for CEL type definitions and schemas.

common/typedef/BUILD

@@ -0,0 +1,196 @@
+# Copyright 2026 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.
+
+load("@com_google_protobuf//bazel:cc_proto_library.bzl", "cc_proto_library")
+load("@com_google_protobuf//bazel:proto_library.bzl", "proto_library")
+load("@rules_cc//cc:cc_library.bzl", "cc_library")
+load("@rules_cc//cc:cc_test.bzl", "cc_test")
+
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+cc_library(
+    name = "typedef",
+    srcs = ["typedef.cc"],
+    hdrs = ["typedef.h"],
+    deps = [
+        "//common:ast",
+        "//common:constant",
+        "@com_google_absl//absl/base:core_headers",
+        "@com_google_absl//absl/base:nullability",
+        "@com_google_absl//absl/container:flat_hash_map",
+        "@com_google_absl//absl/functional:overload",
+        "@com_google_absl//absl/log:absl_check",
+        "@com_google_absl//absl/status",
+        "@com_google_absl//absl/strings",
+        "@com_google_absl//absl/strings:string_view",
+    ],
+)
+
+cc_test(
+    name = "typedef_test",
+    srcs = ["typedef_test.cc"],
+    deps = [
+        ":typedef",
+        "//common:ast",
+        "//common:constant",
+        "//internal:testing",
+        "@com_google_absl//absl/status",
+        "@com_google_absl//absl/status:status_matchers",
+    ],
+)
+
+proto_library(
+    name = "typedef_protos",
+    srcs = ["typedef.proto"],
+    deps = [
+        "@com_google_cel_spec//proto/cel/expr:checked_proto",
+        "@com_google_cel_spec//proto/cel/expr:syntax_proto",
+    ],
+)
+
+cc_proto_library(
+    name = "typedef_cc_proto",
+    deps = [":typedef_protos"],
+)
+
+cc_library(
+    name = "schema_proto",
+    srcs = ["schema_proto.cc"],
+    hdrs = ["schema_proto.h"],
+    deps = [
+        ":typedef_cc_proto",
+        "@com_google_absl//absl/base:core_headers",
+        "@com_google_absl//absl/base:nullability",
+        "@com_google_absl//absl/container:flat_hash_map",
+        "@com_google_absl//absl/status",
+        "@com_google_absl//absl/status:statusor",
+        "@com_google_absl//absl/strings",
+        "@com_google_absl//absl/strings:string_view",
+    ],
+)
+
+cc_test(
+    name = "schema_proto_test",
+    srcs = ["schema_proto_test.cc"],
+    deps = [
+        ":schema_proto",
+        ":typedef_cc_proto",
+        "//internal:testing",
+        "@com_google_absl//absl/status",
+        "@com_google_absl//absl/status:status_matchers",
+        "@com_google_absl//absl/strings:string_view",
+    ],
+)
+
+cc_library(
+    name = "typedef_proto",
+    srcs = ["typedef_proto.cc"],
+    hdrs = ["typedef_proto.h"],
+    deps = [
+        ":schema_proto",
+        ":typedef",
+        ":typedef_cc_proto",
+        "//common:ast",
+        "//common:constant",
+        "//common/ast:constant_proto",
+        "//internal:status_macros",
+        "@com_google_absl//absl/base:nullability",
+        "@com_google_absl//absl/container:flat_hash_map",
+        "@com_google_absl//absl/status",
+        "@com_google_absl//absl/status:statusor",
+        "@com_google_absl//absl/types:span",
+        "@com_google_absl//absl/types:variant",
+        "@com_google_cel_spec//proto/cel/expr:checked_cc_proto",
+        "@com_google_protobuf//:struct_cc_proto",
+    ],
+)
+
+cc_library(
+    name = "proto_schema",
+    hdrs = ["proto_schema.h"],
+    deps = [
+        "@com_google_absl//absl/base:core_headers",
+        "@com_google_absl//absl/strings:string_view",
+    ],
+)
+
+proto_library(
+    name = "proto_schema_protos",
+    srcs = ["proto_schema.proto"],
+    deps = [":typedef_protos"],
+)
+
+cc_proto_library(
+    name = "proto_schema_cc_proto",
+    deps = [":proto_schema_protos"],
+)
+
+cc_library(
+    name = "proto_schema_proto",
+    srcs = ["proto_schema_proto.cc"],
+    hdrs = ["proto_schema_proto.h"],
+    deps = [
+        ":proto_schema",
+        ":proto_schema_cc_proto",
+        ":schema_proto",
+        ":typedef_cc_proto",
+        "@com_google_absl//absl/base:nullability",
+        "@com_google_absl//absl/status",
+        "@com_google_absl//absl/status:statusor",
+        "@com_google_absl//absl/strings",
+        "@com_google_absl//absl/strings:string_view",
+    ],
+)
+
+cc_test(
+    name = "proto_schema_proto_test",
+    srcs = ["proto_schema_proto_test.cc"],
+    deps = [
+        ":proto_schema",
+        ":proto_schema_cc_proto",
+        ":proto_schema_proto",
+        ":schema_proto",
+        ":typedef_cc_proto",
+        "//internal:testing",
+        "@com_google_absl//absl/status",
+        "@com_google_absl//absl/status:status_matchers",
+        "@com_google_protobuf//:protobuf",
+    ],
+)
+
+cc_test(
+    name = "typedef_proto_test",
+    srcs = ["typedef_proto_test.cc"],
+    data = [
+        "//common/typedef/testdata:typedef_testdata",
+    ],
+    deps = [
+        ":proto_schema_proto",
+        ":schema_proto",
+        ":typedef",
+        ":typedef_cc_proto",
+        ":typedef_proto",
+        "//internal:proto_matchers",
+        "//internal:runfiles",
+        "//internal:testing",
+        "@com_google_absl//absl/status",
+        "@com_google_absl//absl/status:status_matchers",
+        "@com_google_absl//absl/status:statusor",
+        "@com_google_absl//absl/strings",
+        "@com_google_absl//absl/strings:string_view",
+        "@com_google_protobuf//:protobuf",
+    ],
+)

common/typedef/proto_schema.h

@@ -0,0 +1,130 @@
+// Copyright 2026 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.
+
+#ifndef THIRD_PARTY_CEL_CPP_COMMON_TYPEDEF_PROTO_SCHEMA_H_
+#define THIRD_PARTY_CEL_CPP_COMMON_TYPEDEF_PROTO_SCHEMA_H_
+
+#include <cstdint>
+#include <optional>
+#include <string>
+#include <utility>
+
+#include "absl/base/attributes.h"
+#include "absl/strings/string_view.h"
+
+namespace cel {
+
+inline constexpr absl::string_view kProto2SchemaName = "proto2";
+inline constexpr absl::string_view kProto3SchemaName = "proto3";
+
+// Protocol Buffers schema properties attached to a StructTypeDef.
+class ProtoStructProperties final {
+ public:
+  ProtoStructProperties() = default;
+  explicit ProtoStructProperties(std::optional<std::string> name)
+      : name_(std::move(name)) {}
+
+  // Overrides the canonical CEL struct name with a target-specific protobuf
+  // message name when they differ (e.g., mapping a canonical CEL type
+  // "com.example.Order" to "com.example.proto2.Order" in proto2 and
+  // "com.example.proto3.Order" in proto3).
+  const std::optional<std::string>& name() const ABSL_ATTRIBUTE_LIFETIME_BOUND {
+    return name_;
+  }
+
+ private:
+  std::optional<std::string> name_;
+};
+
+// Protocol Buffers schema properties attached to a StructTypeDef::Field.
+class ProtoFieldProperties final {
+ public:
+  ProtoFieldProperties() = default;
+  explicit ProtoFieldProperties(
+      std::optional<std::string> name, std::optional<int32_t> id = std::nullopt,
+      std::optional<std::string> json_name = std::nullopt)
+      : name_(std::move(name)), id_(id), json_name_(std::move(json_name)) {}
+
+  // Overrides the canonical CEL field name with the protobuf field name when
+  // they differ (e.g., mapping a CEL field "order_id" to a legacy proto2 field
+  // "order_id_v2", or mapping a camelCase CEL field "userId" to "user_id").
+  const std::optional<std::string>& name() const ABSL_ATTRIBUTE_LIFETIME_BOUND {
+    return name_;
+  }
+
+  // The protobuf field number (tag) in the message definition (e.g., `1` in
+  // `string order_id = 1;`), required for wire serialization and descriptor
+  // generation.
+  std::optional<int32_t> id() const { return id_; }
+
+  // Custom JSON field name specified via the `[json_name = "..."]` field
+  // option when it differs from the default lowerCamelCase of the proto field
+  // name (e.g., `[json_name = "order_id_legacy"]` on field `order_id`).
+  const std::optional<std::string>& json_name() const
+      ABSL_ATTRIBUTE_LIFETIME_BOUND {
+    return json_name_;
+  }
+
+ private:
+  std::optional<std::string> name_;
+  std::optional<int32_t> id_;
+  std::optional<std::string> json_name_;
+};
+
+// Protocol Buffers schema properties attached to an EnumTypeDef.
+class ProtoEnumProperties final {
+ public:
+  ProtoEnumProperties() = default;
+  explicit ProtoEnumProperties(std::optional<std::string> name,
+                               std::optional<bool> allow_alias = std::nullopt)
+      : name_(std::move(name)), allow_alias_(allow_alias) {}
+
+  // Overrides the canonical CEL enum name with a target-specific protobuf enum
+  // name when they differ (e.g., mapping "com.example.OrderStatus" to
+  // "com.example.proto2.OrderStatus").
+  const std::optional<std::string>& name() const ABSL_ATTRIBUTE_LIFETIME_BOUND {
+    return name_;
+  }
+
+  // Whether the protobuf enum sets `option allow_alias = true;`, permitting
+  // multiple enum constants to share the same numeric value (e.g.,
+  // `STARTED = 1;` and `RUNNING = 1;`).
+  std::optional<bool> allow_alias() const { return allow_alias_; }
+
+ private:
+  std::optional<std::string> name_;
+  std::optional<bool> allow_alias_;
+};
+
+// Protocol Buffers schema properties attached to an EnumTypeDef::EnumConstant.
+class ProtoEnumConstantProperties final {
+ public:
+  ProtoEnumConstantProperties() = default;
+  explicit ProtoEnumConstantProperties(std::optional<std::string> name)
+      : name_(std::move(name)) {}
+
+  // Overrides the canonical CEL enum constant name with the protobuf enum value
+  // name when they differ (e.g., mapping a CEL constant "ORDER_STATUS_ACTIVE"
+  // to "STATUS_ACTIVE_V2" in a legacy proto2 enum).
+  const std::optional<std::string>& name() const ABSL_ATTRIBUTE_LIFETIME_BOUND {
+    return name_;
+  }
+
+ private:
+  std::optional<std::string> name_;
+};
+
+}  // namespace cel
+
+#endif  // THIRD_PARTY_CEL_CPP_COMMON_TYPEDEF_PROTO_SCHEMA_H_

common/typedef/proto_schema.proto

@@ -0,0 +1,64 @@
+// Copyright 2026 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.
+
+edition = "2023";
+
+package cel.types;
+
+import "common/typedef/typedef.proto";
+
+option cc_enable_arenas = true;
+
+// Protocol Buffers schema properties attached to a Struct.
+message ProtoStructProperties {
+  string name = 1;
+}
+
+// Protocol Buffers schema properties attached to a Struct.Field.
+message ProtoFieldProperties {
+  string name = 1;
+  int32 id = 2;
+  string json_name = 3;
+}
+
+// Protocol Buffers schema properties attached to an Enum.
+message ProtoEnumProperties {
+  string name = 1;
+  bool allow_alias = 2;
+}
+
+// Protocol Buffers schema properties attached to an Enum.EnumConstant.
+message ProtoEnumConstantProperties {
+  string name = 1;
+}
+
+extend Struct {
+  ProtoStructProperties proto2_struct_schema = 1001;
+  ProtoStructProperties proto3_struct_schema = 1002;
+}
+
+extend Struct.Field {
+  ProtoFieldProperties proto2_field_schema = 1001;
+  ProtoFieldProperties proto3_field_schema = 1002;
+}
+
+extend Enum {
+  ProtoEnumProperties proto2_enum_schema = 1001;
+  ProtoEnumProperties proto3_enum_schema = 1002;
+}
+
+extend Enum.EnumConstant {
+  ProtoEnumConstantProperties proto2_enum_constant_schema = 1001;
+  ProtoEnumConstantProperties proto3_enum_constant_schema = 1002;
+}