Support for CelEnvironment to YAML

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

@@ -89,6 +89,7 @@ java_library(
  name = "environment_yaml_parser",
  srcs = [
  "CelEnvironmentYamlParser.java",
+ "CelEnvironmentYamlSerializer.java",
  ],
  tags = [
  ],

bundle/src/main/java/dev/cel/bundle/CelEnvironment.java

@@ -154,7 +154,7 @@ public static Builder newBuilder() {
  .setVariables(ImmutableSet.of())
  .setFunctions(ImmutableSet.of());
  }
-
+
  /** Extends the provided {@link CelCompiler} environment with this configuration. */
  public CelCompiler extend(CelCompiler celCompiler, CelOptions celOptions)
  throws CelEnvironmentException {

bundle/src/main/java/dev/cel/bundle/CelEnvironmentYamlSerializer.java

@@ -0,0 +1,146 @@
+// 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.
+
+package dev.cel.bundle;
+
+import com.google.common.collect.ImmutableMap;
+import org.yaml.snakeyaml.DumperOptions;
+import org.yaml.snakeyaml.Yaml;
+import org.yaml.snakeyaml.nodes.Node;
+import org.yaml.snakeyaml.representer.Represent;
+import org.yaml.snakeyaml.representer.Representer;
+
+/** Serializes a CelEnvironment into a YAML file. */
+public final class CelEnvironmentYamlSerializer extends Representer {
+
+ private static DumperOptions initDumperOptions() {
+ DumperOptions options = new DumperOptions();
+ options.setIndent(2);
+ options.setPrettyFlow(true);
+ options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK);
+ return options;
+ }
+
+ private static final DumperOptions YAML_OPTIONS = initDumperOptions();
+
+ private static final CelEnvironmentYamlSerializer INSTANCE = new CelEnvironmentYamlSerializer();
+
+ private CelEnvironmentYamlSerializer() {
+ super(YAML_OPTIONS);
+ this.multiRepresenters.put(CelEnvironment.class, new RepresentCelEnvironment());
+ this.multiRepresenters.put(CelEnvironment.VariableDecl.class, new RepresentVariableDecl());
+ this.multiRepresenters.put(CelEnvironment.FunctionDecl.class, new RepresentFunctionDecl());
+ this.multiRepresenters.put(CelEnvironment.OverloadDecl.class, new RepresentOverloadDecl());
+ this.multiRepresenters.put(CelEnvironment.TypeDecl.class, new RepresentTypeDecl());
+ this.multiRepresenters.put(
+ CelEnvironment.ExtensionConfig.class, new RepresentExtensionConfig());
+ }
+
+ public static String toYaml(CelEnvironment environment) {
+ // Yaml is not thread-safe, so we create a new instance for each serialization.
+ Yaml yaml = new Yaml(INSTANCE, YAML_OPTIONS);
+ return yaml.dump(environment);
+ }
+
+ private final class RepresentCelEnvironment implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment environment = (CelEnvironment) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", environment.name());
+ if (!environment.description().isEmpty()) {
+ configMap.put("description", environment.description());
+ }
+ if (!environment.container().isEmpty()) {
+ configMap.put("container", environment.container());
+ }
+ if (!environment.extensions().isEmpty()) {
+ configMap.put("extensions", environment.extensions().asList());
+ }
+ if (!environment.variables().isEmpty()) {
+ configMap.put("variables", environment.variables().asList());
+ }
+ if (!environment.functions().isEmpty()) {
+ configMap.put("functions", environment.functions().asList());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentExtensionConfig implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.ExtensionConfig extension = (CelEnvironment.ExtensionConfig) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", extension.name());
+ if (extension.version() > 0 && extension.version() != Integer.MAX_VALUE) {
+ configMap.put("version", extension.version());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentVariableDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.VariableDecl variable = (CelEnvironment.VariableDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", variable.name()).put("type_name", variable.type().name());
+ if (!variable.type().params().isEmpty()) {
+ configMap.put("params", variable.type().params());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentFunctionDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.FunctionDecl function = (CelEnvironment.FunctionDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", function.name()).put("overloads", function.overloads().asList());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentOverloadDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.OverloadDecl overload = (CelEnvironment.OverloadDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("id", overload.id());
+ if (overload.target().isPresent()) {
+ configMap.put("target", overload.target().get());
+ }
+ configMap.put("args", overload.arguments()).put("return", overload.returnType());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentTypeDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.TypeDecl type = (CelEnvironment.TypeDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("type_name", type.name());
+ if (!type.params().isEmpty()) {
+ configMap.put("params", type.params());
+ }
+ if (type.isTypeParam()) {
+ configMap.put("is_type_param", type.isTypeParam());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+}

bundle/src/test/java/dev/cel/bundle/BUILD.bazel

@@ -10,6 +10,7 @@ java_library(
  testonly = True,
  srcs = glob(["*Test.java"]),
  resources = [
+ "//testing/environment:dump_env",
  "//testing/environment:extended_env",
  ],
  deps = [

bundle/src/test/java/dev/cel/bundle/CelEnvironmentYamlSerializerTest.java

@@ -0,0 +1,124 @@
+// 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.
+
+package dev.cel.bundle;
+
+import static com.google.common.truth.Truth.assertThat;
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.common.base.Ascii;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.io.Resources;
+import dev.cel.bundle.CelEnvironment.ExtensionConfig;
+import dev.cel.bundle.CelEnvironment.FunctionDecl;
+import dev.cel.bundle.CelEnvironment.OverloadDecl;
+import dev.cel.bundle.CelEnvironment.TypeDecl;
+import dev.cel.bundle.CelEnvironment.VariableDecl;
+import java.io.IOException;
+import java.net.URL;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public final class CelEnvironmentYamlSerializerTest {
+
+ @Test
+ public void toYaml_success() throws Exception {
+ CelEnvironment environment =
+ CelEnvironment.newBuilder()
+ .setName("dump_env")
+ .setDescription("dump_env description")
+ .setContainer("test.container")
+ .addExtensions(
+ ImmutableSet.of(
+ ExtensionConfig.of("bindings"),
+ ExtensionConfig.of("encoders"),
+ ExtensionConfig.of("lists"),
+ ExtensionConfig.of("math"),
+ ExtensionConfig.of("optional"),
+ ExtensionConfig.of("protos"),
+ ExtensionConfig.of("sets"),
+ ExtensionConfig.of("strings", 1)))
+ .setVariables(
+ ImmutableSet.of(
+ VariableDecl.create(
+ "request", TypeDecl.create("google.rpc.context.AttributeContext.Request")),
+ VariableDecl.create(
+ "map_var",
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(TypeDecl.create("string"))
+ .addParams(TypeDecl.create("string"))
+ .build())))
+ .setFunctions(
+ ImmutableSet.of(
+ FunctionDecl.create(
+ "getOrDefault",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("getOrDefault_key_value")
+ .setTarget(
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build())
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build())
+ .build())
+ .setArguments(
+ ImmutableList.of(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build(),
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build()))
+ .setReturnType(
+ TypeDecl.newBuilder().setName("V").setIsTypeParam(true).build())
+ .build())),
+ FunctionDecl.create(
+ "coalesce",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("coalesce_null_int")
+ .setTarget(TypeDecl.create("google.protobuf.Int64Value"))
+ .setArguments(ImmutableList.of(TypeDecl.create("int")))
+ .setReturnType(TypeDecl.create("int"))
+ .build()))))
+ .build();
+
+ String yamlOutput = CelEnvironmentYamlSerializer.toYaml(environment);
+ try {
+ String yamlFileContent = readFile("environment/dump_env.yaml");
+ assertThat(yamlFileContent).endsWith(yamlOutput);
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ private static String readFile(String path) throws IOException {
+ URL url = Resources.getResource(Ascii.toLowerCase(path));
+ return Resources.toString(url, UTF_8);
+ }
+}

testing/environment/BUILD.bazel

@@ -4,6 +4,11 @@ package(
  default_visibility = ["//:internal"],
 )
 
+alias(
+ name = "dump_env",
+ actual = "//testing/src/test/resources/environment:dump_env",
+)
+
 alias(
  name = "extended_env",
  actual = "//testing/src/test/resources/environment:extended_env",

testing/src/test/resources/environment/BUILD.bazel

@@ -8,6 +8,11 @@ package(
  ],
 )
 
+filegroup(
+ name = "dump_env",
+ srcs = ["dump_env.yaml"],
+)
+
 filegroup(
  name = "extended_env",
  srcs = ["extended_env.yaml"],

testing/src/test/resources/environment/dump_env.yaml

@@ -0,0 +1,63 @@
+# 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.
+
+name: dump_env
+description: dump_env description
+container: test.container
+extensions:
+- name: bindings
+- name: encoders
+- name: lists
+- name: math
+- name: optional
+- name: protos
+- name: sets
+- name: strings
+ version: 1
+variables:
+- name: request
+ type_name: google.rpc.context.AttributeContext.Request
+- name: map_var
+ type_name: map
+ params:
+ - type_name: string
+ - type_name: string
+functions:
+- name: getOrDefault
+ overloads:
+ - id: getOrDefault_key_value
+ target:
+ type_name: map
+ params:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ args:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ return:
+ type_name: V
+ is_type_param: true
+- name: coalesce
+ overloads:
+ - id: coalesce_null_int
+ target:
+ type_name: google.protobuf.Int64Value
+ args:
+ - type_name: int
+ return:
+ type_name: int

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

@@ -89,6 +89,7 @@ java_library(
  name = "environment_yaml_parser",
  srcs = [
  "CelEnvironmentYamlParser.java",
+ "CelEnvironmentYamlSerializer.java",
  ],
  tags = [
  ],

bundle/src/main/java/dev/cel/bundle/CelEnvironment.java

@@ -154,7 +154,7 @@ public static Builder newBuilder() {
  .setVariables(ImmutableSet.of())
  .setFunctions(ImmutableSet.of());
  }
-
+
  /** Extends the provided {@link CelCompiler} environment with this configuration. */
  public CelCompiler extend(CelCompiler celCompiler, CelOptions celOptions)
  throws CelEnvironmentException {

bundle/src/main/java/dev/cel/bundle/CelEnvironmentYamlSerializer.java

@@ -0,0 +1,146 @@
+// 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.
+
+package dev.cel.bundle;
+
+import com.google.common.collect.ImmutableMap;
+import org.yaml.snakeyaml.DumperOptions;
+import org.yaml.snakeyaml.Yaml;
+import org.yaml.snakeyaml.nodes.Node;
+import org.yaml.snakeyaml.representer.Represent;
+import org.yaml.snakeyaml.representer.Representer;
+
+/** Serializes a CelEnvironment into a YAML file. */
+public final class CelEnvironmentYamlSerializer extends Representer {
+
+ private static DumperOptions initDumperOptions() {
+ DumperOptions options = new DumperOptions();
+ options.setIndent(2);
+ options.setPrettyFlow(true);
+ options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK);
+ return options;
+ }
+
+ private static final DumperOptions YAML_OPTIONS = initDumperOptions();
+
+ private static final CelEnvironmentYamlSerializer INSTANCE = new CelEnvironmentYamlSerializer();
+
+ private CelEnvironmentYamlSerializer() {
+ super(YAML_OPTIONS);
+ this.multiRepresenters.put(CelEnvironment.class, new RepresentCelEnvironment());
+ this.multiRepresenters.put(CelEnvironment.VariableDecl.class, new RepresentVariableDecl());
+ this.multiRepresenters.put(CelEnvironment.FunctionDecl.class, new RepresentFunctionDecl());
+ this.multiRepresenters.put(CelEnvironment.OverloadDecl.class, new RepresentOverloadDecl());
+ this.multiRepresenters.put(CelEnvironment.TypeDecl.class, new RepresentTypeDecl());
+ this.multiRepresenters.put(
+ CelEnvironment.ExtensionConfig.class, new RepresentExtensionConfig());
+ }
+
+ public static String toYaml(CelEnvironment environment) {
+ // Yaml is not thread-safe, so we create a new instance for each serialization.
+ Yaml yaml = new Yaml(INSTANCE, YAML_OPTIONS);
+ return yaml.dump(environment);
+ }
+
+ private final class RepresentCelEnvironment implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment environment = (CelEnvironment) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", environment.name());
+ if (!environment.description().isEmpty()) {
+ configMap.put("description", environment.description());
+ }
+ if (!environment.container().isEmpty()) {
+ configMap.put("container", environment.container());
+ }
+ if (!environment.extensions().isEmpty()) {
+ configMap.put("extensions", environment.extensions().asList());
+ }
+ if (!environment.variables().isEmpty()) {
+ configMap.put("variables", environment.variables().asList());
+ }
+ if (!environment.functions().isEmpty()) {
+ configMap.put("functions", environment.functions().asList());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentExtensionConfig implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.ExtensionConfig extension = (CelEnvironment.ExtensionConfig) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", extension.name());
+ if (extension.version() > 0 && extension.version() != Integer.MAX_VALUE) {
+ configMap.put("version", extension.version());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentVariableDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.VariableDecl variable = (CelEnvironment.VariableDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", variable.name()).put("type_name", variable.type().name());
+ if (!variable.type().params().isEmpty()) {
+ configMap.put("params", variable.type().params());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentFunctionDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.FunctionDecl function = (CelEnvironment.FunctionDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", function.name()).put("overloads", function.overloads().asList());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentOverloadDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.OverloadDecl overload = (CelEnvironment.OverloadDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("id", overload.id());
+ if (overload.target().isPresent()) {
+ configMap.put("target", overload.target().get());
+ }
+ configMap.put("args", overload.arguments()).put("return", overload.returnType());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentTypeDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.TypeDecl type = (CelEnvironment.TypeDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("type_name", type.name());
+ if (!type.params().isEmpty()) {
+ configMap.put("params", type.params());
+ }
+ if (type.isTypeParam()) {
+ configMap.put("is_type_param", type.isTypeParam());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+}

bundle/src/test/java/dev/cel/bundle/BUILD.bazel

@@ -10,6 +10,7 @@ java_library(
  testonly = True,
  srcs = glob(["*Test.java"]),
  resources = [
+ "//testing/environment:dump_env",
  "//testing/environment:extended_env",
  ],
  deps = [

bundle/src/test/java/dev/cel/bundle/CelEnvironmentYamlSerializerTest.java

@@ -0,0 +1,124 @@
+// 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.
+
+package dev.cel.bundle;
+
+import static com.google.common.truth.Truth.assertThat;
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.common.base.Ascii;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.io.Resources;
+import dev.cel.bundle.CelEnvironment.ExtensionConfig;
+import dev.cel.bundle.CelEnvironment.FunctionDecl;
+import dev.cel.bundle.CelEnvironment.OverloadDecl;
+import dev.cel.bundle.CelEnvironment.TypeDecl;
+import dev.cel.bundle.CelEnvironment.VariableDecl;
+import java.io.IOException;
+import java.net.URL;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public final class CelEnvironmentYamlSerializerTest {
+
+ @Test
+ public void toYaml_success() throws Exception {
+ CelEnvironment environment =
+ CelEnvironment.newBuilder()
+ .setName("dump_env")
+ .setDescription("dump_env description")
+ .setContainer("test.container")
+ .addExtensions(
+ ImmutableSet.of(
+ ExtensionConfig.of("bindings"),
+ ExtensionConfig.of("encoders"),
+ ExtensionConfig.of("lists"),
+ ExtensionConfig.of("math"),
+ ExtensionConfig.of("optional"),
+ ExtensionConfig.of("protos"),
+ ExtensionConfig.of("sets"),
+ ExtensionConfig.of("strings", 1)))
+ .setVariables(
+ ImmutableSet.of(
+ VariableDecl.create(
+ "request", TypeDecl.create("google.rpc.context.AttributeContext.Request")),
+ VariableDecl.create(
+ "map_var",
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(TypeDecl.create("string"))
+ .addParams(TypeDecl.create("string"))
+ .build())))
+ .setFunctions(
+ ImmutableSet.of(
+ FunctionDecl.create(
+ "getOrDefault",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("getOrDefault_key_value")
+ .setTarget(
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build())
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build())
+ .build())
+ .setArguments(
+ ImmutableList.of(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build(),
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build()))
+ .setReturnType(
+ TypeDecl.newBuilder().setName("V").setIsTypeParam(true).build())
+ .build())),
+ FunctionDecl.create(
+ "coalesce",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("coalesce_null_int")
+ .setTarget(TypeDecl.create("google.protobuf.Int64Value"))
+ .setArguments(ImmutableList.of(TypeDecl.create("int")))
+ .setReturnType(TypeDecl.create("int"))
+ .build()))))
+ .build();
+
+ String yamlOutput = CelEnvironmentYamlSerializer.toYaml(environment);
+ try {
+ String yamlFileContent = readFile("environment/dump_env.yaml");
+ assertThat(yamlFileContent).endsWith(yamlOutput);
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ private static String readFile(String path) throws IOException {
+ URL url = Resources.getResource(Ascii.toLowerCase(path));
+ return Resources.toString(url, UTF_8);
+ }
+}

testing/environment/BUILD.bazel

@@ -4,6 +4,11 @@ package(
  default_visibility = ["//:internal"],
 )
 
+alias(
+ name = "dump_env",
+ actual = "//testing/src/test/resources/environment:dump_env",
+)
+
 alias(
  name = "extended_env",
  actual = "//testing/src/test/resources/environment:extended_env",

testing/src/test/resources/environment/BUILD.bazel

@@ -8,6 +8,11 @@ package(
  ],
 )
 
+filegroup(
+ name = "dump_env",
+ srcs = ["dump_env.yaml"],
+)
+
 filegroup(
  name = "extended_env",
  srcs = ["extended_env.yaml"],

testing/src/test/resources/environment/dump_env.yaml

@@ -0,0 +1,63 @@
+# 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.
+
+name: dump_env
+description: dump_env description
+container: test.container
+extensions:
+- name: bindings
+- name: encoders
+- name: lists
+- name: math
+- name: optional
+- name: protos
+- name: sets
+- name: strings
+ version: 1
+variables:
+- name: request
+ type_name: google.rpc.context.AttributeContext.Request
+- name: map_var
+ type_name: map
+ params:
+ - type_name: string
+ - type_name: string
+functions:
+- name: getOrDefault
+ overloads:
+ - id: getOrDefault_key_value
+ target:
+ type_name: map
+ params:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ args:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ return:
+ type_name: V
+ is_type_param: true
+- name: coalesce
+ overloads:
+ - id: coalesce_null_int
+ target:
+ type_name: google.protobuf.Int64Value
+ args:
+ - type_name: int
+ return:
+ type_name: int

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

@@ -89,6 +89,7 @@ java_library(
  name = "environment_yaml_parser",
  srcs = [
  "CelEnvironmentYamlParser.java",
+ "CelEnvironmentYamlSerializer.java",
  ],
  tags = [
  ],

bundle/src/main/java/dev/cel/bundle/CelEnvironment.java

@@ -154,7 +154,7 @@ public static Builder newBuilder() {
  .setVariables(ImmutableSet.of())
  .setFunctions(ImmutableSet.of());
  }
-
+
  /** Extends the provided {@link CelCompiler} environment with this configuration. */
  public CelCompiler extend(CelCompiler celCompiler, CelOptions celOptions)
  throws CelEnvironmentException {

bundle/src/main/java/dev/cel/bundle/CelEnvironmentYamlSerializer.java

@@ -0,0 +1,146 @@
+// 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.
+
+package dev.cel.bundle;
+
+import com.google.common.collect.ImmutableMap;
+import org.yaml.snakeyaml.DumperOptions;
+import org.yaml.snakeyaml.Yaml;
+import org.yaml.snakeyaml.nodes.Node;
+import org.yaml.snakeyaml.representer.Represent;
+import org.yaml.snakeyaml.representer.Representer;
+
+/** Serializes a CelEnvironment into a YAML file. */
+public final class CelEnvironmentYamlSerializer extends Representer {
+
+ private static DumperOptions initDumperOptions() {
+ DumperOptions options = new DumperOptions();
+ options.setIndent(2);
+ options.setPrettyFlow(true);
+ options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK);
+ return options;
+ }
+
+ private static final DumperOptions YAML_OPTIONS = initDumperOptions();
+
+ private static final CelEnvironmentYamlSerializer INSTANCE = new CelEnvironmentYamlSerializer();
+
+ private CelEnvironmentYamlSerializer() {
+ super(YAML_OPTIONS);
+ this.multiRepresenters.put(CelEnvironment.class, new RepresentCelEnvironment());
+ this.multiRepresenters.put(CelEnvironment.VariableDecl.class, new RepresentVariableDecl());
+ this.multiRepresenters.put(CelEnvironment.FunctionDecl.class, new RepresentFunctionDecl());
+ this.multiRepresenters.put(CelEnvironment.OverloadDecl.class, new RepresentOverloadDecl());
+ this.multiRepresenters.put(CelEnvironment.TypeDecl.class, new RepresentTypeDecl());
+ this.multiRepresenters.put(
+ CelEnvironment.ExtensionConfig.class, new RepresentExtensionConfig());
+ }
+
+ public static String toYaml(CelEnvironment environment) {
+ // Yaml is not thread-safe, so we create a new instance for each serialization.
+ Yaml yaml = new Yaml(INSTANCE, YAML_OPTIONS);
+ return yaml.dump(environment);
+ }
+
+ private final class RepresentCelEnvironment implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment environment = (CelEnvironment) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", environment.name());
+ if (!environment.description().isEmpty()) {
+ configMap.put("description", environment.description());
+ }
+ if (!environment.container().isEmpty()) {
+ configMap.put("container", environment.container());
+ }
+ if (!environment.extensions().isEmpty()) {
+ configMap.put("extensions", environment.extensions().asList());
+ }
+ if (!environment.variables().isEmpty()) {
+ configMap.put("variables", environment.variables().asList());
+ }
+ if (!environment.functions().isEmpty()) {
+ configMap.put("functions", environment.functions().asList());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentExtensionConfig implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.ExtensionConfig extension = (CelEnvironment.ExtensionConfig) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", extension.name());
+ if (extension.version() > 0 && extension.version() != Integer.MAX_VALUE) {
+ configMap.put("version", extension.version());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentVariableDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.VariableDecl variable = (CelEnvironment.VariableDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", variable.name()).put("type_name", variable.type().name());
+ if (!variable.type().params().isEmpty()) {
+ configMap.put("params", variable.type().params());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentFunctionDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.FunctionDecl function = (CelEnvironment.FunctionDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", function.name()).put("overloads", function.overloads().asList());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentOverloadDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.OverloadDecl overload = (CelEnvironment.OverloadDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("id", overload.id());
+ if (overload.target().isPresent()) {
+ configMap.put("target", overload.target().get());
+ }
+ configMap.put("args", overload.arguments()).put("return", overload.returnType());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentTypeDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.TypeDecl type = (CelEnvironment.TypeDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("type_name", type.name());
+ if (!type.params().isEmpty()) {
+ configMap.put("params", type.params());
+ }
+ if (type.isTypeParam()) {
+ configMap.put("is_type_param", type.isTypeParam());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+}

bundle/src/test/java/dev/cel/bundle/BUILD.bazel

@@ -10,6 +10,7 @@ java_library(
  testonly = True,
  srcs = glob(["*Test.java"]),
  resources = [
+ "//testing/environment:dump_env",
  "//testing/environment:extended_env",
  ],
  deps = [

bundle/src/test/java/dev/cel/bundle/CelEnvironmentYamlSerializerTest.java

@@ -0,0 +1,124 @@
+// 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.
+
+package dev.cel.bundle;
+
+import static com.google.common.truth.Truth.assertThat;
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.common.base.Ascii;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.io.Resources;
+import dev.cel.bundle.CelEnvironment.ExtensionConfig;
+import dev.cel.bundle.CelEnvironment.FunctionDecl;
+import dev.cel.bundle.CelEnvironment.OverloadDecl;
+import dev.cel.bundle.CelEnvironment.TypeDecl;
+import dev.cel.bundle.CelEnvironment.VariableDecl;
+import java.io.IOException;
+import java.net.URL;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public final class CelEnvironmentYamlSerializerTest {
+
+ @Test
+ public void toYaml_success() throws Exception {
+ CelEnvironment environment =
+ CelEnvironment.newBuilder()
+ .setName("dump_env")
+ .setDescription("dump_env description")
+ .setContainer("test.container")
+ .addExtensions(
+ ImmutableSet.of(
+ ExtensionConfig.of("bindings"),
+ ExtensionConfig.of("encoders"),
+ ExtensionConfig.of("lists"),
+ ExtensionConfig.of("math"),
+ ExtensionConfig.of("optional"),
+ ExtensionConfig.of("protos"),
+ ExtensionConfig.of("sets"),
+ ExtensionConfig.of("strings", 1)))
+ .setVariables(
+ ImmutableSet.of(
+ VariableDecl.create(
+ "request", TypeDecl.create("google.rpc.context.AttributeContext.Request")),
+ VariableDecl.create(
+ "map_var",
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(TypeDecl.create("string"))
+ .addParams(TypeDecl.create("string"))
+ .build())))
+ .setFunctions(
+ ImmutableSet.of(
+ FunctionDecl.create(
+ "getOrDefault",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("getOrDefault_key_value")
+ .setTarget(
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build())
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build())
+ .build())
+ .setArguments(
+ ImmutableList.of(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build(),
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build()))
+ .setReturnType(
+ TypeDecl.newBuilder().setName("V").setIsTypeParam(true).build())
+ .build())),
+ FunctionDecl.create(
+ "coalesce",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("coalesce_null_int")
+ .setTarget(TypeDecl.create("google.protobuf.Int64Value"))
+ .setArguments(ImmutableList.of(TypeDecl.create("int")))
+ .setReturnType(TypeDecl.create("int"))
+ .build()))))
+ .build();
+
+ String yamlOutput = CelEnvironmentYamlSerializer.toYaml(environment);
+ try {
+ String yamlFileContent = readFile("environment/dump_env.yaml");
+ assertThat(yamlFileContent).endsWith(yamlOutput);
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ private static String readFile(String path) throws IOException {
+ URL url = Resources.getResource(Ascii.toLowerCase(path));
+ return Resources.toString(url, UTF_8);
+ }
+}

testing/environment/BUILD.bazel

@@ -4,6 +4,11 @@ package(
  default_visibility = ["//:internal"],
 )
 
+alias(
+ name = "dump_env",
+ actual = "//testing/src/test/resources/environment:dump_env",
+)
+
 alias(
  name = "extended_env",
  actual = "//testing/src/test/resources/environment:extended_env",

testing/src/test/resources/environment/BUILD.bazel

@@ -8,6 +8,11 @@ package(
  ],
 )
 
+filegroup(
+ name = "dump_env",
+ srcs = ["dump_env.yaml"],
+)
+
 filegroup(
  name = "extended_env",
  srcs = ["extended_env.yaml"],

testing/src/test/resources/environment/dump_env.yaml

@@ -0,0 +1,63 @@
+# 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.
+
+name: dump_env
+description: dump_env description
+container: test.container
+extensions:
+- name: bindings
+- name: encoders
+- name: lists
+- name: math
+- name: optional
+- name: protos
+- name: sets
+- name: strings
+ version: 1
+variables:
+- name: request
+ type_name: google.rpc.context.AttributeContext.Request
+- name: map_var
+ type_name: map
+ params:
+ - type_name: string
+ - type_name: string
+functions:
+- name: getOrDefault
+ overloads:
+ - id: getOrDefault_key_value
+ target:
+ type_name: map
+ params:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ args:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ return:
+ type_name: V
+ is_type_param: true
+- name: coalesce
+ overloads:
+ - id: coalesce_null_int
+ target:
+ type_name: google.protobuf.Int64Value
+ args:
+ - type_name: int
+ return:
+ type_name: int

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

@@ -89,6 +89,7 @@ java_library(
  name = "environment_yaml_parser",
  srcs = [
  "CelEnvironmentYamlParser.java",
+ "CelEnvironmentYamlSerializer.java",
  ],
  tags = [
  ],

bundle/src/main/java/dev/cel/bundle/CelEnvironment.java

@@ -154,7 +154,7 @@ public static Builder newBuilder() {
  .setVariables(ImmutableSet.of())
  .setFunctions(ImmutableSet.of());
  }
-
+
  /** Extends the provided {@link CelCompiler} environment with this configuration. */
  public CelCompiler extend(CelCompiler celCompiler, CelOptions celOptions)
  throws CelEnvironmentException {

bundle/src/main/java/dev/cel/bundle/CelEnvironmentYamlSerializer.java

@@ -0,0 +1,146 @@
+// 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.
+
+package dev.cel.bundle;
+
+import com.google.common.collect.ImmutableMap;
+import org.yaml.snakeyaml.DumperOptions;
+import org.yaml.snakeyaml.Yaml;
+import org.yaml.snakeyaml.nodes.Node;
+import org.yaml.snakeyaml.representer.Represent;
+import org.yaml.snakeyaml.representer.Representer;
+
+/** Serializes a CelEnvironment into a YAML file. */
+public final class CelEnvironmentYamlSerializer extends Representer {
+
+ private static DumperOptions initDumperOptions() {
+ DumperOptions options = new DumperOptions();
+ options.setIndent(2);
+ options.setPrettyFlow(true);
+ options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK);
+ return options;
+ }
+
+ private static final DumperOptions YAML_OPTIONS = initDumperOptions();
+
+ private static final CelEnvironmentYamlSerializer INSTANCE = new CelEnvironmentYamlSerializer();
+
+ private CelEnvironmentYamlSerializer() {
+ super(YAML_OPTIONS);
+ this.multiRepresenters.put(CelEnvironment.class, new RepresentCelEnvironment());
+ this.multiRepresenters.put(CelEnvironment.VariableDecl.class, new RepresentVariableDecl());
+ this.multiRepresenters.put(CelEnvironment.FunctionDecl.class, new RepresentFunctionDecl());
+ this.multiRepresenters.put(CelEnvironment.OverloadDecl.class, new RepresentOverloadDecl());
+ this.multiRepresenters.put(CelEnvironment.TypeDecl.class, new RepresentTypeDecl());
+ this.multiRepresenters.put(
+ CelEnvironment.ExtensionConfig.class, new RepresentExtensionConfig());
+ }
+
+ public static String toYaml(CelEnvironment environment) {
+ // Yaml is not thread-safe, so we create a new instance for each serialization.
+ Yaml yaml = new Yaml(INSTANCE, YAML_OPTIONS);
+ return yaml.dump(environment);
+ }
+
+ private final class RepresentCelEnvironment implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment environment = (CelEnvironment) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", environment.name());
+ if (!environment.description().isEmpty()) {
+ configMap.put("description", environment.description());
+ }
+ if (!environment.container().isEmpty()) {
+ configMap.put("container", environment.container());
+ }
+ if (!environment.extensions().isEmpty()) {
+ configMap.put("extensions", environment.extensions().asList());
+ }
+ if (!environment.variables().isEmpty()) {
+ configMap.put("variables", environment.variables().asList());
+ }
+ if (!environment.functions().isEmpty()) {
+ configMap.put("functions", environment.functions().asList());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentExtensionConfig implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.ExtensionConfig extension = (CelEnvironment.ExtensionConfig) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", extension.name());
+ if (extension.version() > 0 && extension.version() != Integer.MAX_VALUE) {
+ configMap.put("version", extension.version());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentVariableDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.VariableDecl variable = (CelEnvironment.VariableDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", variable.name()).put("type_name", variable.type().name());
+ if (!variable.type().params().isEmpty()) {
+ configMap.put("params", variable.type().params());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentFunctionDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.FunctionDecl function = (CelEnvironment.FunctionDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", function.name()).put("overloads", function.overloads().asList());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentOverloadDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.OverloadDecl overload = (CelEnvironment.OverloadDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("id", overload.id());
+ if (overload.target().isPresent()) {
+ configMap.put("target", overload.target().get());
+ }
+ configMap.put("args", overload.arguments()).put("return", overload.returnType());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentTypeDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.TypeDecl type = (CelEnvironment.TypeDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("type_name", type.name());
+ if (!type.params().isEmpty()) {
+ configMap.put("params", type.params());
+ }
+ if (type.isTypeParam()) {
+ configMap.put("is_type_param", type.isTypeParam());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+}

bundle/src/test/java/dev/cel/bundle/BUILD.bazel

@@ -10,6 +10,7 @@ java_library(
  testonly = True,
  srcs = glob(["*Test.java"]),
  resources = [
+ "//testing/environment:dump_env",
  "//testing/environment:extended_env",
  ],
  deps = [

bundle/src/test/java/dev/cel/bundle/CelEnvironmentYamlSerializerTest.java

@@ -0,0 +1,124 @@
+// 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.
+
+package dev.cel.bundle;
+
+import static com.google.common.truth.Truth.assertThat;
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.common.base.Ascii;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.io.Resources;
+import dev.cel.bundle.CelEnvironment.ExtensionConfig;
+import dev.cel.bundle.CelEnvironment.FunctionDecl;
+import dev.cel.bundle.CelEnvironment.OverloadDecl;
+import dev.cel.bundle.CelEnvironment.TypeDecl;
+import dev.cel.bundle.CelEnvironment.VariableDecl;
+import java.io.IOException;
+import java.net.URL;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public final class CelEnvironmentYamlSerializerTest {
+
+ @Test
+ public void toYaml_success() throws Exception {
+ CelEnvironment environment =
+ CelEnvironment.newBuilder()
+ .setName("dump_env")
+ .setDescription("dump_env description")
+ .setContainer("test.container")
+ .addExtensions(
+ ImmutableSet.of(
+ ExtensionConfig.of("bindings"),
+ ExtensionConfig.of("encoders"),
+ ExtensionConfig.of("lists"),
+ ExtensionConfig.of("math"),
+ ExtensionConfig.of("optional"),
+ ExtensionConfig.of("protos"),
+ ExtensionConfig.of("sets"),
+ ExtensionConfig.of("strings", 1)))
+ .setVariables(
+ ImmutableSet.of(
+ VariableDecl.create(
+ "request", TypeDecl.create("google.rpc.context.AttributeContext.Request")),
+ VariableDecl.create(
+ "map_var",
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(TypeDecl.create("string"))
+ .addParams(TypeDecl.create("string"))
+ .build())))
+ .setFunctions(
+ ImmutableSet.of(
+ FunctionDecl.create(
+ "getOrDefault",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("getOrDefault_key_value")
+ .setTarget(
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build())
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build())
+ .build())
+ .setArguments(
+ ImmutableList.of(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build(),
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build()))
+ .setReturnType(
+ TypeDecl.newBuilder().setName("V").setIsTypeParam(true).build())
+ .build())),
+ FunctionDecl.create(
+ "coalesce",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("coalesce_null_int")
+ .setTarget(TypeDecl.create("google.protobuf.Int64Value"))
+ .setArguments(ImmutableList.of(TypeDecl.create("int")))
+ .setReturnType(TypeDecl.create("int"))
+ .build()))))
+ .build();
+
+ String yamlOutput = CelEnvironmentYamlSerializer.toYaml(environment);
+ try {
+ String yamlFileContent = readFile("environment/dump_env.yaml");
+ assertThat(yamlFileContent).endsWith(yamlOutput);
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ private static String readFile(String path) throws IOException {
+ URL url = Resources.getResource(Ascii.toLowerCase(path));
+ return Resources.toString(url, UTF_8);
+ }
+}

testing/environment/BUILD.bazel

@@ -4,6 +4,11 @@ package(
  default_visibility = ["//:internal"],
 )
 
+alias(
+ name = "dump_env",
+ actual = "//testing/src/test/resources/environment:dump_env",
+)
+
 alias(
  name = "extended_env",
  actual = "//testing/src/test/resources/environment:extended_env",

testing/src/test/resources/environment/BUILD.bazel

@@ -8,6 +8,11 @@ package(
  ],
 )
 
+filegroup(
+ name = "dump_env",
+ srcs = ["dump_env.yaml"],
+)
+
 filegroup(
  name = "extended_env",
  srcs = ["extended_env.yaml"],

testing/src/test/resources/environment/dump_env.yaml

@@ -0,0 +1,63 @@
+# 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.
+
+name: dump_env
+description: dump_env description
+container: test.container
+extensions:
+- name: bindings
+- name: encoders
+- name: lists
+- name: math
+- name: optional
+- name: protos
+- name: sets
+- name: strings
+ version: 1
+variables:
+- name: request
+ type_name: google.rpc.context.AttributeContext.Request
+- name: map_var
+ type_name: map
+ params:
+ - type_name: string
+ - type_name: string
+functions:
+- name: getOrDefault
+ overloads:
+ - id: getOrDefault_key_value
+ target:
+ type_name: map
+ params:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ args:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ return:
+ type_name: V
+ is_type_param: true
+- name: coalesce
+ overloads:
+ - id: coalesce_null_int
+ target:
+ type_name: google.protobuf.Int64Value
+ args:
+ - type_name: int
+ return:
+ type_name: int

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

@@ -89,6 +89,7 @@ java_library(
  name = "environment_yaml_parser",
  srcs = [
  "CelEnvironmentYamlParser.java",
+ "CelEnvironmentYamlSerializer.java",
  ],
  tags = [
  ],

bundle/src/main/java/dev/cel/bundle/CelEnvironment.java

@@ -154,7 +154,7 @@ public static Builder newBuilder() {
  .setVariables(ImmutableSet.of())
  .setFunctions(ImmutableSet.of());
  }
-
+
  /** Extends the provided {@link CelCompiler} environment with this configuration. */
  public CelCompiler extend(CelCompiler celCompiler, CelOptions celOptions)
  throws CelEnvironmentException {

bundle/src/main/java/dev/cel/bundle/CelEnvironmentYamlSerializer.java

@@ -0,0 +1,146 @@
+// 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.
+
+package dev.cel.bundle;
+
+import com.google.common.collect.ImmutableMap;
+import org.yaml.snakeyaml.DumperOptions;
+import org.yaml.snakeyaml.Yaml;
+import org.yaml.snakeyaml.nodes.Node;
+import org.yaml.snakeyaml.representer.Represent;
+import org.yaml.snakeyaml.representer.Representer;
+
+/** Serializes a CelEnvironment into a YAML file. */
+public final class CelEnvironmentYamlSerializer extends Representer {
+
+ private static DumperOptions initDumperOptions() {
+ DumperOptions options = new DumperOptions();
+ options.setIndent(2);
+ options.setPrettyFlow(true);
+ options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK);
+ return options;
+ }
+
+ private static final DumperOptions YAML_OPTIONS = initDumperOptions();
+
+ private static final CelEnvironmentYamlSerializer INSTANCE = new CelEnvironmentYamlSerializer();
+
+ private CelEnvironmentYamlSerializer() {
+ super(YAML_OPTIONS);
+ this.multiRepresenters.put(CelEnvironment.class, new RepresentCelEnvironment());
+ this.multiRepresenters.put(CelEnvironment.VariableDecl.class, new RepresentVariableDecl());
+ this.multiRepresenters.put(CelEnvironment.FunctionDecl.class, new RepresentFunctionDecl());
+ this.multiRepresenters.put(CelEnvironment.OverloadDecl.class, new RepresentOverloadDecl());
+ this.multiRepresenters.put(CelEnvironment.TypeDecl.class, new RepresentTypeDecl());
+ this.multiRepresenters.put(
+ CelEnvironment.ExtensionConfig.class, new RepresentExtensionConfig());
+ }
+
+ public static String toYaml(CelEnvironment environment) {
+ // Yaml is not thread-safe, so we create a new instance for each serialization.
+ Yaml yaml = new Yaml(INSTANCE, YAML_OPTIONS);
+ return yaml.dump(environment);
+ }
+
+ private final class RepresentCelEnvironment implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment environment = (CelEnvironment) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", environment.name());
+ if (!environment.description().isEmpty()) {
+ configMap.put("description", environment.description());
+ }
+ if (!environment.container().isEmpty()) {
+ configMap.put("container", environment.container());
+ }
+ if (!environment.extensions().isEmpty()) {
+ configMap.put("extensions", environment.extensions().asList());
+ }
+ if (!environment.variables().isEmpty()) {
+ configMap.put("variables", environment.variables().asList());
+ }
+ if (!environment.functions().isEmpty()) {
+ configMap.put("functions", environment.functions().asList());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentExtensionConfig implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.ExtensionConfig extension = (CelEnvironment.ExtensionConfig) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", extension.name());
+ if (extension.version() > 0 && extension.version() != Integer.MAX_VALUE) {
+ configMap.put("version", extension.version());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentVariableDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.VariableDecl variable = (CelEnvironment.VariableDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", variable.name()).put("type_name", variable.type().name());
+ if (!variable.type().params().isEmpty()) {
+ configMap.put("params", variable.type().params());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentFunctionDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.FunctionDecl function = (CelEnvironment.FunctionDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", function.name()).put("overloads", function.overloads().asList());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentOverloadDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.OverloadDecl overload = (CelEnvironment.OverloadDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("id", overload.id());
+ if (overload.target().isPresent()) {
+ configMap.put("target", overload.target().get());
+ }
+ configMap.put("args", overload.arguments()).put("return", overload.returnType());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentTypeDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.TypeDecl type = (CelEnvironment.TypeDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("type_name", type.name());
+ if (!type.params().isEmpty()) {
+ configMap.put("params", type.params());
+ }
+ if (type.isTypeParam()) {
+ configMap.put("is_type_param", type.isTypeParam());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+}

bundle/src/test/java/dev/cel/bundle/BUILD.bazel

@@ -10,6 +10,7 @@ java_library(
  testonly = True,
  srcs = glob(["*Test.java"]),
  resources = [
+ "//testing/environment:dump_env",
  "//testing/environment:extended_env",
  ],
  deps = [

bundle/src/test/java/dev/cel/bundle/CelEnvironmentYamlSerializerTest.java

@@ -0,0 +1,124 @@
+// 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.
+
+package dev.cel.bundle;
+
+import static com.google.common.truth.Truth.assertThat;
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.common.base.Ascii;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.io.Resources;
+import dev.cel.bundle.CelEnvironment.ExtensionConfig;
+import dev.cel.bundle.CelEnvironment.FunctionDecl;
+import dev.cel.bundle.CelEnvironment.OverloadDecl;
+import dev.cel.bundle.CelEnvironment.TypeDecl;
+import dev.cel.bundle.CelEnvironment.VariableDecl;
+import java.io.IOException;
+import java.net.URL;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public final class CelEnvironmentYamlSerializerTest {
+
+ @Test
+ public void toYaml_success() throws Exception {
+ CelEnvironment environment =
+ CelEnvironment.newBuilder()
+ .setName("dump_env")
+ .setDescription("dump_env description")
+ .setContainer("test.container")
+ .addExtensions(
+ ImmutableSet.of(
+ ExtensionConfig.of("bindings"),
+ ExtensionConfig.of("encoders"),
+ ExtensionConfig.of("lists"),
+ ExtensionConfig.of("math"),
+ ExtensionConfig.of("optional"),
+ ExtensionConfig.of("protos"),
+ ExtensionConfig.of("sets"),
+ ExtensionConfig.of("strings", 1)))
+ .setVariables(
+ ImmutableSet.of(
+ VariableDecl.create(
+ "request", TypeDecl.create("google.rpc.context.AttributeContext.Request")),
+ VariableDecl.create(
+ "map_var",
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(TypeDecl.create("string"))
+ .addParams(TypeDecl.create("string"))
+ .build())))
+ .setFunctions(
+ ImmutableSet.of(
+ FunctionDecl.create(
+ "getOrDefault",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("getOrDefault_key_value")
+ .setTarget(
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build())
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build())
+ .build())
+ .setArguments(
+ ImmutableList.of(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build(),
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build()))
+ .setReturnType(
+ TypeDecl.newBuilder().setName("V").setIsTypeParam(true).build())
+ .build())),
+ FunctionDecl.create(
+ "coalesce",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("coalesce_null_int")
+ .setTarget(TypeDecl.create("google.protobuf.Int64Value"))
+ .setArguments(ImmutableList.of(TypeDecl.create("int")))
+ .setReturnType(TypeDecl.create("int"))
+ .build()))))
+ .build();
+
+ String yamlOutput = CelEnvironmentYamlSerializer.toYaml(environment);
+ try {
+ String yamlFileContent = readFile("environment/dump_env.yaml");
+ assertThat(yamlFileContent).endsWith(yamlOutput);
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ private static String readFile(String path) throws IOException {
+ URL url = Resources.getResource(Ascii.toLowerCase(path));
+ return Resources.toString(url, UTF_8);
+ }
+}

testing/environment/BUILD.bazel

@@ -4,6 +4,11 @@ package(
  default_visibility = ["//:internal"],
 )
 
+alias(
+ name = "dump_env",
+ actual = "//testing/src/test/resources/environment:dump_env",
+)
+
 alias(
  name = "extended_env",
  actual = "//testing/src/test/resources/environment:extended_env",

testing/src/test/resources/environment/BUILD.bazel

@@ -8,6 +8,11 @@ package(
  ],
 )
 
+filegroup(
+ name = "dump_env",
+ srcs = ["dump_env.yaml"],
+)
+
 filegroup(
  name = "extended_env",
  srcs = ["extended_env.yaml"],

testing/src/test/resources/environment/dump_env.yaml

@@ -0,0 +1,63 @@
+# 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.
+
+name: dump_env
+description: dump_env description
+container: test.container
+extensions:
+- name: bindings
+- name: encoders
+- name: lists
+- name: math
+- name: optional
+- name: protos
+- name: sets
+- name: strings
+ version: 1
+variables:
+- name: request
+ type_name: google.rpc.context.AttributeContext.Request
+- name: map_var
+ type_name: map
+ params:
+ - type_name: string
+ - type_name: string
+functions:
+- name: getOrDefault
+ overloads:
+ - id: getOrDefault_key_value
+ target:
+ type_name: map
+ params:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ args:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ return:
+ type_name: V
+ is_type_param: true
+- name: coalesce
+ overloads:
+ - id: coalesce_null_int
+ target:
+ type_name: google.protobuf.Int64Value
+ args:
+ - type_name: int
+ return:
+ type_name: int

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

@@ -89,6 +89,7 @@ java_library(
  name = "environment_yaml_parser",
  srcs = [
  "CelEnvironmentYamlParser.java",
+ "CelEnvironmentYamlSerializer.java",
  ],
  tags = [
  ],

bundle/src/main/java/dev/cel/bundle/CelEnvironment.java

@@ -154,7 +154,7 @@ public static Builder newBuilder() {
  .setVariables(ImmutableSet.of())
  .setFunctions(ImmutableSet.of());
  }
-
+
  /** Extends the provided {@link CelCompiler} environment with this configuration. */
  public CelCompiler extend(CelCompiler celCompiler, CelOptions celOptions)
  throws CelEnvironmentException {

bundle/src/main/java/dev/cel/bundle/CelEnvironmentYamlSerializer.java

@@ -0,0 +1,146 @@
+// 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.
+
+package dev.cel.bundle;
+
+import com.google.common.collect.ImmutableMap;
+import org.yaml.snakeyaml.DumperOptions;
+import org.yaml.snakeyaml.Yaml;
+import org.yaml.snakeyaml.nodes.Node;
+import org.yaml.snakeyaml.representer.Represent;
+import org.yaml.snakeyaml.representer.Representer;
+
+/** Serializes a CelEnvironment into a YAML file. */
+public final class CelEnvironmentYamlSerializer extends Representer {
+
+ private static DumperOptions initDumperOptions() {
+ DumperOptions options = new DumperOptions();
+ options.setIndent(2);
+ options.setPrettyFlow(true);
+ options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK);
+ return options;
+ }
+
+ private static final DumperOptions YAML_OPTIONS = initDumperOptions();
+
+ private static final CelEnvironmentYamlSerializer INSTANCE = new CelEnvironmentYamlSerializer();
+
+ private CelEnvironmentYamlSerializer() {
+ super(YAML_OPTIONS);
+ this.multiRepresenters.put(CelEnvironment.class, new RepresentCelEnvironment());
+ this.multiRepresenters.put(CelEnvironment.VariableDecl.class, new RepresentVariableDecl());
+ this.multiRepresenters.put(CelEnvironment.FunctionDecl.class, new RepresentFunctionDecl());
+ this.multiRepresenters.put(CelEnvironment.OverloadDecl.class, new RepresentOverloadDecl());
+ this.multiRepresenters.put(CelEnvironment.TypeDecl.class, new RepresentTypeDecl());
+ this.multiRepresenters.put(
+ CelEnvironment.ExtensionConfig.class, new RepresentExtensionConfig());
+ }
+
+ public static String toYaml(CelEnvironment environment) {
+ // Yaml is not thread-safe, so we create a new instance for each serialization.
+ Yaml yaml = new Yaml(INSTANCE, YAML_OPTIONS);
+ return yaml.dump(environment);
+ }
+
+ private final class RepresentCelEnvironment implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment environment = (CelEnvironment) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", environment.name());
+ if (!environment.description().isEmpty()) {
+ configMap.put("description", environment.description());
+ }
+ if (!environment.container().isEmpty()) {
+ configMap.put("container", environment.container());
+ }
+ if (!environment.extensions().isEmpty()) {
+ configMap.put("extensions", environment.extensions().asList());
+ }
+ if (!environment.variables().isEmpty()) {
+ configMap.put("variables", environment.variables().asList());
+ }
+ if (!environment.functions().isEmpty()) {
+ configMap.put("functions", environment.functions().asList());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentExtensionConfig implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.ExtensionConfig extension = (CelEnvironment.ExtensionConfig) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", extension.name());
+ if (extension.version() > 0 && extension.version() != Integer.MAX_VALUE) {
+ configMap.put("version", extension.version());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentVariableDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.VariableDecl variable = (CelEnvironment.VariableDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", variable.name()).put("type_name", variable.type().name());
+ if (!variable.type().params().isEmpty()) {
+ configMap.put("params", variable.type().params());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentFunctionDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.FunctionDecl function = (CelEnvironment.FunctionDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", function.name()).put("overloads", function.overloads().asList());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentOverloadDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.OverloadDecl overload = (CelEnvironment.OverloadDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("id", overload.id());
+ if (overload.target().isPresent()) {
+ configMap.put("target", overload.target().get());
+ }
+ configMap.put("args", overload.arguments()).put("return", overload.returnType());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentTypeDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.TypeDecl type = (CelEnvironment.TypeDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("type_name", type.name());
+ if (!type.params().isEmpty()) {
+ configMap.put("params", type.params());
+ }
+ if (type.isTypeParam()) {
+ configMap.put("is_type_param", type.isTypeParam());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+}

bundle/src/test/java/dev/cel/bundle/BUILD.bazel

@@ -10,6 +10,7 @@ java_library(
  testonly = True,
  srcs = glob(["*Test.java"]),
  resources = [
+ "//testing/environment:dump_env",
  "//testing/environment:extended_env",
  ],
  deps = [

bundle/src/test/java/dev/cel/bundle/CelEnvironmentYamlSerializerTest.java

@@ -0,0 +1,124 @@
+// 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.
+
+package dev.cel.bundle;
+
+import static com.google.common.truth.Truth.assertThat;
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.common.base.Ascii;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.io.Resources;
+import dev.cel.bundle.CelEnvironment.ExtensionConfig;
+import dev.cel.bundle.CelEnvironment.FunctionDecl;
+import dev.cel.bundle.CelEnvironment.OverloadDecl;
+import dev.cel.bundle.CelEnvironment.TypeDecl;
+import dev.cel.bundle.CelEnvironment.VariableDecl;
+import java.io.IOException;
+import java.net.URL;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public final class CelEnvironmentYamlSerializerTest {
+
+ @Test
+ public void toYaml_success() throws Exception {
+ CelEnvironment environment =
+ CelEnvironment.newBuilder()
+ .setName("dump_env")
+ .setDescription("dump_env description")
+ .setContainer("test.container")
+ .addExtensions(
+ ImmutableSet.of(
+ ExtensionConfig.of("bindings"),
+ ExtensionConfig.of("encoders"),
+ ExtensionConfig.of("lists"),
+ ExtensionConfig.of("math"),
+ ExtensionConfig.of("optional"),
+ ExtensionConfig.of("protos"),
+ ExtensionConfig.of("sets"),
+ ExtensionConfig.of("strings", 1)))
+ .setVariables(
+ ImmutableSet.of(
+ VariableDecl.create(
+ "request", TypeDecl.create("google.rpc.context.AttributeContext.Request")),
+ VariableDecl.create(
+ "map_var",
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(TypeDecl.create("string"))
+ .addParams(TypeDecl.create("string"))
+ .build())))
+ .setFunctions(
+ ImmutableSet.of(
+ FunctionDecl.create(
+ "getOrDefault",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("getOrDefault_key_value")
+ .setTarget(
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build())
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build())
+ .build())
+ .setArguments(
+ ImmutableList.of(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build(),
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build()))
+ .setReturnType(
+ TypeDecl.newBuilder().setName("V").setIsTypeParam(true).build())
+ .build())),
+ FunctionDecl.create(
+ "coalesce",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("coalesce_null_int")
+ .setTarget(TypeDecl.create("google.protobuf.Int64Value"))
+ .setArguments(ImmutableList.of(TypeDecl.create("int")))
+ .setReturnType(TypeDecl.create("int"))
+ .build()))))
+ .build();
+
+ String yamlOutput = CelEnvironmentYamlSerializer.toYaml(environment);
+ try {
+ String yamlFileContent = readFile("environment/dump_env.yaml");
+ assertThat(yamlFileContent).endsWith(yamlOutput);
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ private static String readFile(String path) throws IOException {
+ URL url = Resources.getResource(Ascii.toLowerCase(path));
+ return Resources.toString(url, UTF_8);
+ }
+}

testing/environment/BUILD.bazel

@@ -4,6 +4,11 @@ package(
  default_visibility = ["//:internal"],
 )
 
+alias(
+ name = "dump_env",
+ actual = "//testing/src/test/resources/environment:dump_env",
+)
+
 alias(
  name = "extended_env",
  actual = "//testing/src/test/resources/environment:extended_env",

testing/src/test/resources/environment/BUILD.bazel

@@ -8,6 +8,11 @@ package(
  ],
 )
 
+filegroup(
+ name = "dump_env",
+ srcs = ["dump_env.yaml"],
+)
+
 filegroup(
  name = "extended_env",
  srcs = ["extended_env.yaml"],

testing/src/test/resources/environment/dump_env.yaml

@@ -0,0 +1,63 @@
+# 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.
+
+name: dump_env
+description: dump_env description
+container: test.container
+extensions:
+- name: bindings
+- name: encoders
+- name: lists
+- name: math
+- name: optional
+- name: protos
+- name: sets
+- name: strings
+ version: 1
+variables:
+- name: request
+ type_name: google.rpc.context.AttributeContext.Request
+- name: map_var
+ type_name: map
+ params:
+ - type_name: string
+ - type_name: string
+functions:
+- name: getOrDefault
+ overloads:
+ - id: getOrDefault_key_value
+ target:
+ type_name: map
+ params:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ args:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ return:
+ type_name: V
+ is_type_param: true
+- name: coalesce
+ overloads:
+ - id: coalesce_null_int
+ target:
+ type_name: google.protobuf.Int64Value
+ args:
+ - type_name: int
+ return:
+ type_name: int

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

@@ -89,6 +89,7 @@ java_library(
  name = "environment_yaml_parser",
  srcs = [
  "CelEnvironmentYamlParser.java",
+ "CelEnvironmentYamlSerializer.java",
  ],
  tags = [
  ],

bundle/src/main/java/dev/cel/bundle/CelEnvironment.java

@@ -154,7 +154,7 @@ public static Builder newBuilder() {
  .setVariables(ImmutableSet.of())
  .setFunctions(ImmutableSet.of());
  }
-
+
  /** Extends the provided {@link CelCompiler} environment with this configuration. */
  public CelCompiler extend(CelCompiler celCompiler, CelOptions celOptions)
  throws CelEnvironmentException {

bundle/src/main/java/dev/cel/bundle/CelEnvironmentYamlSerializer.java

@@ -0,0 +1,146 @@
+// 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.
+
+package dev.cel.bundle;
+
+import com.google.common.collect.ImmutableMap;
+import org.yaml.snakeyaml.DumperOptions;
+import org.yaml.snakeyaml.Yaml;
+import org.yaml.snakeyaml.nodes.Node;
+import org.yaml.snakeyaml.representer.Represent;
+import org.yaml.snakeyaml.representer.Representer;
+
+/** Serializes a CelEnvironment into a YAML file. */
+public final class CelEnvironmentYamlSerializer extends Representer {
+
+ private static DumperOptions initDumperOptions() {
+ DumperOptions options = new DumperOptions();
+ options.setIndent(2);
+ options.setPrettyFlow(true);
+ options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK);
+ return options;
+ }
+
+ private static final DumperOptions YAML_OPTIONS = initDumperOptions();
+
+ private static final CelEnvironmentYamlSerializer INSTANCE = new CelEnvironmentYamlSerializer();
+
+ private CelEnvironmentYamlSerializer() {
+ super(YAML_OPTIONS);
+ this.multiRepresenters.put(CelEnvironment.class, new RepresentCelEnvironment());
+ this.multiRepresenters.put(CelEnvironment.VariableDecl.class, new RepresentVariableDecl());
+ this.multiRepresenters.put(CelEnvironment.FunctionDecl.class, new RepresentFunctionDecl());
+ this.multiRepresenters.put(CelEnvironment.OverloadDecl.class, new RepresentOverloadDecl());
+ this.multiRepresenters.put(CelEnvironment.TypeDecl.class, new RepresentTypeDecl());
+ this.multiRepresenters.put(
+ CelEnvironment.ExtensionConfig.class, new RepresentExtensionConfig());
+ }
+
+ public static String toYaml(CelEnvironment environment) {
+ // Yaml is not thread-safe, so we create a new instance for each serialization.
+ Yaml yaml = new Yaml(INSTANCE, YAML_OPTIONS);
+ return yaml.dump(environment);
+ }
+
+ private final class RepresentCelEnvironment implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment environment = (CelEnvironment) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", environment.name());
+ if (!environment.description().isEmpty()) {
+ configMap.put("description", environment.description());
+ }
+ if (!environment.container().isEmpty()) {
+ configMap.put("container", environment.container());
+ }
+ if (!environment.extensions().isEmpty()) {
+ configMap.put("extensions", environment.extensions().asList());
+ }
+ if (!environment.variables().isEmpty()) {
+ configMap.put("variables", environment.variables().asList());
+ }
+ if (!environment.functions().isEmpty()) {
+ configMap.put("functions", environment.functions().asList());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentExtensionConfig implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.ExtensionConfig extension = (CelEnvironment.ExtensionConfig) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", extension.name());
+ if (extension.version() > 0 && extension.version() != Integer.MAX_VALUE) {
+ configMap.put("version", extension.version());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentVariableDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.VariableDecl variable = (CelEnvironment.VariableDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", variable.name()).put("type_name", variable.type().name());
+ if (!variable.type().params().isEmpty()) {
+ configMap.put("params", variable.type().params());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentFunctionDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.FunctionDecl function = (CelEnvironment.FunctionDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", function.name()).put("overloads", function.overloads().asList());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentOverloadDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.OverloadDecl overload = (CelEnvironment.OverloadDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("id", overload.id());
+ if (overload.target().isPresent()) {
+ configMap.put("target", overload.target().get());
+ }
+ configMap.put("args", overload.arguments()).put("return", overload.returnType());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentTypeDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.TypeDecl type = (CelEnvironment.TypeDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("type_name", type.name());
+ if (!type.params().isEmpty()) {
+ configMap.put("params", type.params());
+ }
+ if (type.isTypeParam()) {
+ configMap.put("is_type_param", type.isTypeParam());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+}

bundle/src/test/java/dev/cel/bundle/BUILD.bazel

@@ -10,6 +10,7 @@ java_library(
  testonly = True,
  srcs = glob(["*Test.java"]),
  resources = [
+ "//testing/environment:dump_env",
  "//testing/environment:extended_env",
  ],
  deps = [

bundle/src/test/java/dev/cel/bundle/CelEnvironmentYamlSerializerTest.java

@@ -0,0 +1,124 @@
+// 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.
+
+package dev.cel.bundle;
+
+import static com.google.common.truth.Truth.assertThat;
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.common.base.Ascii;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.io.Resources;
+import dev.cel.bundle.CelEnvironment.ExtensionConfig;
+import dev.cel.bundle.CelEnvironment.FunctionDecl;
+import dev.cel.bundle.CelEnvironment.OverloadDecl;
+import dev.cel.bundle.CelEnvironment.TypeDecl;
+import dev.cel.bundle.CelEnvironment.VariableDecl;
+import java.io.IOException;
+import java.net.URL;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public final class CelEnvironmentYamlSerializerTest {
+
+ @Test
+ public void toYaml_success() throws Exception {
+ CelEnvironment environment =
+ CelEnvironment.newBuilder()
+ .setName("dump_env")
+ .setDescription("dump_env description")
+ .setContainer("test.container")
+ .addExtensions(
+ ImmutableSet.of(
+ ExtensionConfig.of("bindings"),
+ ExtensionConfig.of("encoders"),
+ ExtensionConfig.of("lists"),
+ ExtensionConfig.of("math"),
+ ExtensionConfig.of("optional"),
+ ExtensionConfig.of("protos"),
+ ExtensionConfig.of("sets"),
+ ExtensionConfig.of("strings", 1)))
+ .setVariables(
+ ImmutableSet.of(
+ VariableDecl.create(
+ "request", TypeDecl.create("google.rpc.context.AttributeContext.Request")),
+ VariableDecl.create(
+ "map_var",
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(TypeDecl.create("string"))
+ .addParams(TypeDecl.create("string"))
+ .build())))
+ .setFunctions(
+ ImmutableSet.of(
+ FunctionDecl.create(
+ "getOrDefault",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("getOrDefault_key_value")
+ .setTarget(
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build())
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build())
+ .build())
+ .setArguments(
+ ImmutableList.of(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build(),
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build()))
+ .setReturnType(
+ TypeDecl.newBuilder().setName("V").setIsTypeParam(true).build())
+ .build())),
+ FunctionDecl.create(
+ "coalesce",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("coalesce_null_int")
+ .setTarget(TypeDecl.create("google.protobuf.Int64Value"))
+ .setArguments(ImmutableList.of(TypeDecl.create("int")))
+ .setReturnType(TypeDecl.create("int"))
+ .build()))))
+ .build();
+
+ String yamlOutput = CelEnvironmentYamlSerializer.toYaml(environment);
+ try {
+ String yamlFileContent = readFile("environment/dump_env.yaml");
+ assertThat(yamlFileContent).endsWith(yamlOutput);
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ private static String readFile(String path) throws IOException {
+ URL url = Resources.getResource(Ascii.toLowerCase(path));
+ return Resources.toString(url, UTF_8);
+ }
+}

testing/environment/BUILD.bazel

@@ -4,6 +4,11 @@ package(
  default_visibility = ["//:internal"],
 )
 
+alias(
+ name = "dump_env",
+ actual = "//testing/src/test/resources/environment:dump_env",
+)
+
 alias(
  name = "extended_env",
  actual = "//testing/src/test/resources/environment:extended_env",

testing/src/test/resources/environment/BUILD.bazel

@@ -8,6 +8,11 @@ package(
  ],
 )
 
+filegroup(
+ name = "dump_env",
+ srcs = ["dump_env.yaml"],
+)
+
 filegroup(
  name = "extended_env",
  srcs = ["extended_env.yaml"],

testing/src/test/resources/environment/dump_env.yaml

@@ -0,0 +1,63 @@
+# 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.
+
+name: dump_env
+description: dump_env description
+container: test.container
+extensions:
+- name: bindings
+- name: encoders
+- name: lists
+- name: math
+- name: optional
+- name: protos
+- name: sets
+- name: strings
+ version: 1
+variables:
+- name: request
+ type_name: google.rpc.context.AttributeContext.Request
+- name: map_var
+ type_name: map
+ params:
+ - type_name: string
+ - type_name: string
+functions:
+- name: getOrDefault
+ overloads:
+ - id: getOrDefault_key_value
+ target:
+ type_name: map
+ params:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ args:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ return:
+ type_name: V
+ is_type_param: true
+- name: coalesce
+ overloads:
+ - id: coalesce_null_int
+ target:
+ type_name: google.protobuf.Int64Value
+ args:
+ - type_name: int
+ return:
+ type_name: int

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

@@ -89,6 +89,7 @@ java_library(
  name = "environment_yaml_parser",
  srcs = [
  "CelEnvironmentYamlParser.java",
+ "CelEnvironmentYamlSerializer.java",
  ],
  tags = [
  ],

bundle/src/main/java/dev/cel/bundle/CelEnvironment.java

@@ -154,7 +154,7 @@ public static Builder newBuilder() {
  .setVariables(ImmutableSet.of())
  .setFunctions(ImmutableSet.of());
  }
-
+
  /** Extends the provided {@link CelCompiler} environment with this configuration. */
  public CelCompiler extend(CelCompiler celCompiler, CelOptions celOptions)
  throws CelEnvironmentException {

bundle/src/main/java/dev/cel/bundle/CelEnvironmentYamlSerializer.java

@@ -0,0 +1,146 @@
+// 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.
+
+package dev.cel.bundle;
+
+import com.google.common.collect.ImmutableMap;
+import org.yaml.snakeyaml.DumperOptions;
+import org.yaml.snakeyaml.Yaml;
+import org.yaml.snakeyaml.nodes.Node;
+import org.yaml.snakeyaml.representer.Represent;
+import org.yaml.snakeyaml.representer.Representer;
+
+/** Serializes a CelEnvironment into a YAML file. */
+public final class CelEnvironmentYamlSerializer extends Representer {
+
+ private static DumperOptions initDumperOptions() {
+ DumperOptions options = new DumperOptions();
+ options.setIndent(2);
+ options.setPrettyFlow(true);
+ options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK);
+ return options;
+ }
+
+ private static final DumperOptions YAML_OPTIONS = initDumperOptions();
+
+ private static final CelEnvironmentYamlSerializer INSTANCE = new CelEnvironmentYamlSerializer();
+
+ private CelEnvironmentYamlSerializer() {
+ super(YAML_OPTIONS);
+ this.multiRepresenters.put(CelEnvironment.class, new RepresentCelEnvironment());
+ this.multiRepresenters.put(CelEnvironment.VariableDecl.class, new RepresentVariableDecl());
+ this.multiRepresenters.put(CelEnvironment.FunctionDecl.class, new RepresentFunctionDecl());
+ this.multiRepresenters.put(CelEnvironment.OverloadDecl.class, new RepresentOverloadDecl());
+ this.multiRepresenters.put(CelEnvironment.TypeDecl.class, new RepresentTypeDecl());
+ this.multiRepresenters.put(
+ CelEnvironment.ExtensionConfig.class, new RepresentExtensionConfig());
+ }
+
+ public static String toYaml(CelEnvironment environment) {
+ // Yaml is not thread-safe, so we create a new instance for each serialization.
+ Yaml yaml = new Yaml(INSTANCE, YAML_OPTIONS);
+ return yaml.dump(environment);
+ }
+
+ private final class RepresentCelEnvironment implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment environment = (CelEnvironment) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", environment.name());
+ if (!environment.description().isEmpty()) {
+ configMap.put("description", environment.description());
+ }
+ if (!environment.container().isEmpty()) {
+ configMap.put("container", environment.container());
+ }
+ if (!environment.extensions().isEmpty()) {
+ configMap.put("extensions", environment.extensions().asList());
+ }
+ if (!environment.variables().isEmpty()) {
+ configMap.put("variables", environment.variables().asList());
+ }
+ if (!environment.functions().isEmpty()) {
+ configMap.put("functions", environment.functions().asList());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentExtensionConfig implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.ExtensionConfig extension = (CelEnvironment.ExtensionConfig) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", extension.name());
+ if (extension.version() > 0 && extension.version() != Integer.MAX_VALUE) {
+ configMap.put("version", extension.version());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentVariableDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.VariableDecl variable = (CelEnvironment.VariableDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", variable.name()).put("type_name", variable.type().name());
+ if (!variable.type().params().isEmpty()) {
+ configMap.put("params", variable.type().params());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentFunctionDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.FunctionDecl function = (CelEnvironment.FunctionDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("name", function.name()).put("overloads", function.overloads().asList());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentOverloadDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.OverloadDecl overload = (CelEnvironment.OverloadDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("id", overload.id());
+ if (overload.target().isPresent()) {
+ configMap.put("target", overload.target().get());
+ }
+ configMap.put("args", overload.arguments()).put("return", overload.returnType());
+ return represent(configMap.buildOrThrow());
+ }
+ }
+
+ private final class RepresentTypeDecl implements Represent {
+ @Override
+ public Node representData(Object data) {
+ CelEnvironment.TypeDecl type = (CelEnvironment.TypeDecl) data;
+ ImmutableMap.Builder<String, Object> configMap = new ImmutableMap.Builder<>();
+ configMap.put("type_name", type.name());
+ if (!type.params().isEmpty()) {
+ configMap.put("params", type.params());
+ }
+ if (type.isTypeParam()) {
+ configMap.put("is_type_param", type.isTypeParam());
+ }
+ return represent(configMap.buildOrThrow());
+ }
+ }
+}

bundle/src/test/java/dev/cel/bundle/BUILD.bazel

@@ -10,6 +10,7 @@ java_library(
  testonly = True,
  srcs = glob(["*Test.java"]),
  resources = [
+ "//testing/environment:dump_env",
  "//testing/environment:extended_env",
  ],
  deps = [

bundle/src/test/java/dev/cel/bundle/CelEnvironmentYamlSerializerTest.java

@@ -0,0 +1,124 @@
+// 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.
+
+package dev.cel.bundle;
+
+import static com.google.common.truth.Truth.assertThat;
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.common.base.Ascii;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.io.Resources;
+import dev.cel.bundle.CelEnvironment.ExtensionConfig;
+import dev.cel.bundle.CelEnvironment.FunctionDecl;
+import dev.cel.bundle.CelEnvironment.OverloadDecl;
+import dev.cel.bundle.CelEnvironment.TypeDecl;
+import dev.cel.bundle.CelEnvironment.VariableDecl;
+import java.io.IOException;
+import java.net.URL;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public final class CelEnvironmentYamlSerializerTest {
+
+ @Test
+ public void toYaml_success() throws Exception {
+ CelEnvironment environment =
+ CelEnvironment.newBuilder()
+ .setName("dump_env")
+ .setDescription("dump_env description")
+ .setContainer("test.container")
+ .addExtensions(
+ ImmutableSet.of(
+ ExtensionConfig.of("bindings"),
+ ExtensionConfig.of("encoders"),
+ ExtensionConfig.of("lists"),
+ ExtensionConfig.of("math"),
+ ExtensionConfig.of("optional"),
+ ExtensionConfig.of("protos"),
+ ExtensionConfig.of("sets"),
+ ExtensionConfig.of("strings", 1)))
+ .setVariables(
+ ImmutableSet.of(
+ VariableDecl.create(
+ "request", TypeDecl.create("google.rpc.context.AttributeContext.Request")),
+ VariableDecl.create(
+ "map_var",
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(TypeDecl.create("string"))
+ .addParams(TypeDecl.create("string"))
+ .build())))
+ .setFunctions(
+ ImmutableSet.of(
+ FunctionDecl.create(
+ "getOrDefault",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("getOrDefault_key_value")
+ .setTarget(
+ TypeDecl.newBuilder()
+ .setName("map")
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build())
+ .addParams(
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build())
+ .build())
+ .setArguments(
+ ImmutableList.of(
+ TypeDecl.newBuilder()
+ .setName("K")
+ .setIsTypeParam(true)
+ .build(),
+ TypeDecl.newBuilder()
+ .setName("V")
+ .setIsTypeParam(true)
+ .build()))
+ .setReturnType(
+ TypeDecl.newBuilder().setName("V").setIsTypeParam(true).build())
+ .build())),
+ FunctionDecl.create(
+ "coalesce",
+ ImmutableSet.of(
+ OverloadDecl.newBuilder()
+ .setId("coalesce_null_int")
+ .setTarget(TypeDecl.create("google.protobuf.Int64Value"))
+ .setArguments(ImmutableList.of(TypeDecl.create("int")))
+ .setReturnType(TypeDecl.create("int"))
+ .build()))))
+ .build();
+
+ String yamlOutput = CelEnvironmentYamlSerializer.toYaml(environment);
+ try {
+ String yamlFileContent = readFile("environment/dump_env.yaml");
+ assertThat(yamlFileContent).endsWith(yamlOutput);
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ private static String readFile(String path) throws IOException {
+ URL url = Resources.getResource(Ascii.toLowerCase(path));
+ return Resources.toString(url, UTF_8);
+ }
+}

testing/environment/BUILD.bazel

@@ -4,6 +4,11 @@ package(
  default_visibility = ["//:internal"],
 )
 
+alias(
+ name = "dump_env",
+ actual = "//testing/src/test/resources/environment:dump_env",
+)
+
 alias(
  name = "extended_env",
  actual = "//testing/src/test/resources/environment:extended_env",

testing/src/test/resources/environment/BUILD.bazel

@@ -8,6 +8,11 @@ package(
  ],
 )
 
+filegroup(
+ name = "dump_env",
+ srcs = ["dump_env.yaml"],
+)
+
 filegroup(
  name = "extended_env",
  srcs = ["extended_env.yaml"],

testing/src/test/resources/environment/dump_env.yaml

@@ -0,0 +1,63 @@
+# 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.
+
+name: dump_env
+description: dump_env description
+container: test.container
+extensions:
+- name: bindings
+- name: encoders
+- name: lists
+- name: math
+- name: optional
+- name: protos
+- name: sets
+- name: strings
+ version: 1
+variables:
+- name: request
+ type_name: google.rpc.context.AttributeContext.Request
+- name: map_var
+ type_name: map
+ params:
+ - type_name: string
+ - type_name: string
+functions:
+- name: getOrDefault
+ overloads:
+ - id: getOrDefault_key_value
+ target:
+ type_name: map
+ params:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ args:
+ - type_name: K
+ is_type_param: true
+ - type_name: V
+ is_type_param: true
+ return:
+ type_name: V
+ is_type_param: true
+- name: coalesce
+ overloads:
+ - id: coalesce_null_int
+ target:
+ type_name: google.protobuf.Int64Value
+ args:
+ - type_name: int
+ return:
+ type_name: int