Implement codegen for CelLiteDescriptor

WORKSPACE

@@ -242,11 +242,11 @@ http_archive(
 )
 
 # cel-spec api/expr canonical protos
-CEL_SPEC_VERSION = "0.20.0"
+CEL_SPEC_VERSION = "0.22.1"
 
 http_archive(
     name = "cel_spec",
-    sha256 = "9f4acb83116f68af8a6b6acf700561a22a1bd8a9ad2f49bf642b7f9b8f285043",
+    sha256 = "1f1ad32bce5d31cf82e9c8f40685b1902de3ab07c78403601e7a43c3fb4de9a6",
     strip_prefix = "cel-spec-" + CEL_SPEC_VERSION,
     urls = [
         "https://github.com/google/cel-spec/archive/" +

common/internal/BUILD.bazel

@@ -95,6 +95,10 @@ java_library(
 
 cel_android_library(
     name = "internal_android",
-    visibility = ["//:android_allow_list"],
     exports = ["//common/src/main/java/dev/cel/common/internal:internal_android"],
 )
+
+java_library(
+    name = "proto_java_qualified_names",
+    exports = ["//common/src/main/java/dev/cel/common/internal:proto_java_qualified_names"],
+)

common/src/main/java/dev/cel/common/internal/BUILD.bazel

@@ -309,6 +309,7 @@ java_library(
     tags = [
     ],
     deps = [
+        "//common/annotations",
         "@maven//:com_google_guava_guava",
         "@maven//:com_google_protobuf_protobuf_java",
     ],

common/src/main/java/dev/cel/common/internal/ProtoJavaQualifiedNames.java

@@ -24,10 +24,16 @@
 import com.google.protobuf.Descriptors.FileDescriptor;
 import com.google.protobuf.Descriptors.GenericDescriptor;
 import com.google.protobuf.Descriptors.ServiceDescriptor;
+import dev.cel.common.annotations.Internal;
 import java.util.ArrayDeque;
 
-/** Helper class for constructing a fully qualified Java class name from a protobuf descriptor. */
-final class ProtoJavaQualifiedNames {
+/**
+ * Helper class for constructing a fully qualified Java class name from a protobuf descriptor. * *
+ *
+ * <p>CEL Library Internals. Do Not Use.
+ */
+@Internal
+public final class ProtoJavaQualifiedNames {
   // Controls how many times we should recursively inspect a nested message for building fully
   // qualified java class name before aborting.
   private static final int SAFE_RECURSE_LIMIT = 50;
@@ -45,6 +51,10 @@ public static String getFullyQualifiedJavaClassName(Descriptor descriptor) {
     return getFullyQualifiedJavaClassNameImpl(descriptor);
   }
 
+  public static String getFullyQualifiedJavaClassName(EnumDescriptor descriptor) {
+    return getFullyQualifiedJavaClassNameImpl(descriptor);
+  }
+
   private static String getFullyQualifiedJavaClassNameImpl(GenericDescriptor descriptor) {
     StringBuilder fullClassName = new StringBuilder();
 

java_lite_proto_cel_library.bzl

@@ -0,0 +1,99 @@
+# Copyright 2025 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.
+
+"""Starlark rule for generating descriptors that is compatible with Protolite Messages."""
+
+load("@rules_java//java:defs.bzl", "java_library")
+load("@rules_proto//proto:defs.bzl", "proto_descriptor_set")
+load("//publish:cel_version.bzl", "CEL_VERSION")
+
+def java_lite_proto_cel_library(
+        name,
+        java_descriptor_class_prefix,
+        deps,
+        debug = False):
+    """Generates a CelLiteDescriptor
+
+    Args:
+       name: name of this target.
+       java_descriptor_class_prefix: Prefix name for the generated descriptor java class (ex: 'TestAllTypes' generates 'TestAllTypesCelLiteDescriptor.java').
+       deps: Name of the proto_library target. Only a single proto_library is supported at this time.
+       debug: (optional) If true, prints additional information during codegen for debugging purposes.
+    """
+    if not name:
+        fail("You must provide a name.")
+
+    if not java_descriptor_class_prefix:
+        fail("You must provide a descriptor_class_prefix.")
+
+    if not deps:
+        fail("You must provide a proto_library dependency.")
+
+    if len(deps) > 1:
+        fail("You must provide only one proto_library dependency.")
+
+    _generate_cel_lite_descriptor_class(
+        name,
+        java_descriptor_class_prefix + "CelLiteDescriptor",
+        deps[0],
+        debug,
+    )
+
+    descriptor_codegen_deps = [
+        "//protobuf:cel_lite_descriptor",
+    ]
+
+    java_library(
+        name = name,
+        srcs = [":" + name + "_cel_lite_descriptor"],
+        deps = deps + descriptor_codegen_deps,
+    )
+
+def _generate_cel_lite_descriptor_class(
+        name,
+        descriptor_class_name,
+        proto_src,
+        debug):
+    outfile = "%s.java" % descriptor_class_name
+
+    transitive_descriptor_set_name = "%s_transitive_descriptor_set" % name
+    proto_descriptor_set(
+        name = transitive_descriptor_set_name,
+        deps = [proto_src],
+    )
+
+    direct_descriptor_set_name = proto_src
+
+    debug_flag = "--debug" if debug else ""
+
+    cmd = (
+        "$(location //protobuf:cel_lite_descriptor_generator) " +
+        "--descriptor $(location %s) " % direct_descriptor_set_name +
+        "--transitive_descriptor_set $(location %s) " % transitive_descriptor_set_name +
+        "--descriptor_class_name %s " % descriptor_class_name +
+        "--out $(location %s) " % outfile +
+        "--version %s " % CEL_VERSION +
+        debug_flag
+    )
+
+    native.genrule(
+        name = name + "_cel_lite_descriptor",
+        srcs = [
+            transitive_descriptor_set_name,
+            direct_descriptor_set_name,
+        ],
+        cmd = cmd,
+        outs = [outfile],
+        tools = ["//protobuf:cel_lite_descriptor_generator"],
+    )

protobuf/BUILD.bazel

@@ -0,0 +1,17 @@
+load("@rules_java//java:defs.bzl", "java_library")
+
+package(
+    default_applicable_licenses = ["//:license"],
+    default_visibility = ["//:internal"],  # TODO: Expose when ready
+)
+
+java_library(
+    name = "cel_lite_descriptor",
+    exports = ["//protobuf/src/main/java/dev/cel/protobuf:cel_lite_descriptor"],
+)
+
+alias(
+    name = "cel_lite_descriptor_generator",
+    actual = "//protobuf/src/main/java/dev/cel/protobuf:cel_lite_descriptor_generator",
+    visibility = ["//:internal"],
+)

protobuf/src/main/java/dev/cel/protobuf/BUILD.bazel

@@ -0,0 +1,77 @@
+load("@rules_java//java:defs.bzl", "java_binary", "java_library")
+
+package(
+    default_applicable_licenses = ["//:license"],
+    default_visibility = ["//protobuf:__pkg__"],
+)
+
+filegroup(
+    name = "cel_lite_descriptor_template_file",
+    srcs = ["templates/cel_lite_descriptor_template.txt"],
+    visibility = ["//visibility:private"],
+)
+
+java_binary(
+    name = "cel_lite_descriptor_generator",
+    srcs = ["CelLiteDescriptorGenerator.java"],
+    main_class = "dev.cel.protobuf.CelLiteDescriptorGenerator",
+    deps = [
+        ":debug_printer",
+        ":java_file_generator",
+        ":proto_descriptor_collector",
+        "//common:cel_descriptors",
+        "//common/internal:proto_java_qualified_names",
+        "@maven//:com_google_guava_guava",
+        "@maven//:com_google_protobuf_protobuf_java",
+        "@maven//:info_picocli_picocli",
+    ],
+)
+
+java_library(
+    name = "proto_descriptor_collector",
+    srcs = ["ProtoDescriptorCollector.java"],
+    deps = [
+        ":cel_lite_descriptor",
+        ":debug_printer",
+        "//common:cel_descriptors",
+        "//common/internal:proto_java_qualified_names",
+        "//common/internal:well_known_proto",
+        "@maven//:com_google_guava_guava",
+        "@maven//:com_google_protobuf_protobuf_java",
+    ],
+)
+
+java_library(
+    name = "java_file_generator",
+    srcs = ["JavaFileGenerator.java"],
+    resources = [
+        ":cel_lite_descriptor_template_file",
+    ],
+    deps = [
+        ":cel_lite_descriptor",
+        "//:auto_value",
+        "@maven//:com_google_guava_guava",
+        "@maven//:org_freemarker_freemarker",
+    ],
+)
+
+java_library(
+    name = "debug_printer",
+    srcs = ["DebugPrinter.java"],
+    deps = [
+        "@maven//:info_picocli_picocli",
+    ],
+)
+
+java_library(
+    name = "cel_lite_descriptor",
+    srcs = ["CelLiteDescriptor.java"],
+    tags = [
+    ],
+    deps = [
+        "//common/annotations",
+        "@maven//:com_google_errorprone_error_prone_annotations",
+        "@maven//:com_google_guava_guava",
+        "@maven//:com_google_protobuf_protobuf_java",
+    ],
+)