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Add code for Exercise 6 Codelabs
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‎codelab/README.md‎

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@@ -16,6 +16,7 @@ Some key areas covered are:
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* [Creating variables](#creating-variables)
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* [Commutatibe logical AND/OR](#logical-andor)
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* [Adding custom functions](#custom-functions)
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* [Building Protos](#building-protos)
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### Prerequisites
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This codelab builds upon a basic understanding of Protocol Buffers and Java.
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The compiler's `addVar` method allows us to declare variables. Note that you must supply the type of the variable being declared. Supported CEL types can be found [here](https://github.com/google/cel-java/tree/main/common/src/main/java/dev/cel/common/types).
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> [!TIP]
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> Best practice: You may have noticed addVar has an overloaded method which accepts a proto based Type instead of the CEL-Java native CelType used in this example. While the two types are functionally equivalent, we recommend using the native types whenever possible.
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> Best practice: You may have noticed `addVar` has an overloaded method which accepts a proto based Type instead of the CEL-Java native CelType used in this example. While the two types are functionally equivalent, we recommend using the native types whenever possible.
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Let's make the evaluation work now. Copy into the eval method:
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@@ -635,3 +636,6 @@ private static boolean mapContainsKeyValue(Object[] args) {
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> [!TIP]
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> Best practice: Declare overload ids according to their types and function names. e.g. targetType_func_argType_argType. In the case where argType is a type param, use a descriptive name instead of the simple type name.
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## Building Protos
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CEL can also build protobuf messages for any message type compiled into the application.

‎codelab/src/main/codelab/Exercise6.java‎

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// Copyright 2024 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package codelab;
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import com.google.rpc.context.AttributeContext.Request;
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import dev.cel.common.CelAbstractSyntaxTree;
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import dev.cel.common.CelValidationException;
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import dev.cel.common.types.StructTypeReference;
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import dev.cel.compiler.CelCompiler;
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import dev.cel.compiler.CelCompilerFactory;
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import dev.cel.runtime.CelEvaluationException;
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import dev.cel.runtime.CelRuntime;
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import dev.cel.runtime.CelRuntimeFactory;
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import java.util.Map;
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/**
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* Exercise6 describes how to build proto message types within CEL.
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*
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* <p>Given an input `jwt` and time `now` construct a `google.rpc.context.AttributeContext.Request`
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* with the `time` and `auth` fields populated according to the
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* google.rpc.context.AttributeContext.Request specification.
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*/
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final class Exercise6 {
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/**
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* Compiles the input expression.
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*
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* @throws IllegalArgumentException If the expression is malformed due to syntactic or semantic
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* errors.
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*/
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CelAbstractSyntaxTree compile(String expression) {
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CelCompiler celCompiler =
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CelCompilerFactory.standardCelCompilerBuilder()
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// Set the container here for "google.rpc.context.AttributeContext"
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// Declare variables for "jwt" and "now" here
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.addMessageTypes(Request.getDescriptor())
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.setResultType(StructTypeReference.create(Request.getDescriptor().getFullName()))
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.build();
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try {
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return celCompiler.compile(expression).getAst();
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} catch (CelValidationException e) {
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throw new IllegalArgumentException("Failed to compile expression.", e);
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}
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}
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/** Evaluates the compiled AST with the user provided parameter values. */
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Object eval(CelAbstractSyntaxTree ast, Map<String, ?> parameterValues) {
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CelRuntime celRuntime =
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CelRuntimeFactory.standardCelRuntimeBuilder()
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.addMessageTypes(Request.getDescriptor())
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.build();
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try {
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CelRuntime.Program program = celRuntime.createProgram(ast);
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return program.eval(parameterValues);
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} catch (CelEvaluationException e) {
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throw new IllegalArgumentException("Evaluation error has occurred.", e);
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}
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}
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}

‎codelab/src/main/codelab/solutions/Exercise6.java‎

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// Copyright 2024 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package codelab.solutions;
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import com.google.rpc.context.AttributeContext.Request;
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import dev.cel.common.CelAbstractSyntaxTree;
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import dev.cel.common.CelValidationException;
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import dev.cel.common.types.SimpleType;
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import dev.cel.common.types.StructTypeReference;
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import dev.cel.compiler.CelCompiler;
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import dev.cel.compiler.CelCompilerFactory;
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import dev.cel.runtime.CelEvaluationException;
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import dev.cel.runtime.CelRuntime;
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import dev.cel.runtime.CelRuntimeFactory;
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import java.util.Map;
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/**
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* Exercise6 describes how to build proto message types within CEL.
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*
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* <p>Given an input `jwt` and time `now` construct a `google.rpc.context.AttributeContext.Request`
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* with the `time` and `auth` fields populated according to the
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* google.rpc.context.AttributeContext.Request specification.
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*/
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final class Exercise6 {
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/**
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* Compiles the input expression.
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*
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* @throws IllegalArgumentException If the expression is malformed due to syntactic or semantic
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* errors.
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*/
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CelAbstractSyntaxTree compile(String expression) {
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CelCompiler celCompiler =
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CelCompilerFactory.standardCelCompilerBuilder()
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.setContainer("google.rpc.context.AttributeContext")
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.addVar("jwt", SimpleType.DYN)
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.addVar("now", SimpleType.TIMESTAMP)
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.addMessageTypes(Request.getDescriptor())
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.setResultType(StructTypeReference.create(Request.getDescriptor().getFullName()))
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.build();
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try {
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return celCompiler.compile(expression).getAst();
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} catch (CelValidationException e) {
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throw new IllegalArgumentException("Failed to compile expression.", e);
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}
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}
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/** Evaluates the compiled AST with the user provided parameter values. */
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Object eval(CelAbstractSyntaxTree ast, Map<String, ?> parameterValues) {
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CelRuntime celRuntime =
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CelRuntimeFactory.standardCelRuntimeBuilder()
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.addMessageTypes(Request.getDescriptor())
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.build();
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try {
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CelRuntime.Program program = celRuntime.createProgram(ast);
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return program.eval(parameterValues);
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} catch (CelEvaluationException e) {
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throw new IllegalArgumentException("Evaluation error has occurred.", e);
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}
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}
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}

‎codelab/src/test/codelab/BUILD.bazel‎

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@@ -82,6 +82,24 @@ java_test(
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],
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)
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java_test(
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name = "Exercise6Test",
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srcs = ["Exercise6Test.java"],
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tags = ["notap"],
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test_class = "codelab.Exercise6Test",
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deps = [
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"//:java_truth",
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"//codelab",
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"//common",
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"@maven//:com_google_api_grpc_proto_google_common_protos",
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"@maven//:com_google_guava_guava",
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"@maven//:com_google_protobuf_protobuf_java",
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"@maven//:com_google_protobuf_protobuf_java_util",
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"@maven//:com_google_testparameterinjector_test_parameter_injector",
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"@maven//:junit_junit",
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],
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)
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test_suite(
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name = "exercise_test_suite",
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tags = ["notap"],

‎codelab/src/test/codelab/Exercise6Test.java‎

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// Copyright 2024 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package codelab;
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import static com.google.common.truth.Truth.assertThat;
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import com.google.common.collect.ImmutableMap;
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import com.google.protobuf.Struct;
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import com.google.protobuf.Timestamp;
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import com.google.protobuf.Value;
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import com.google.protobuf.util.Timestamps;
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import com.google.rpc.context.AttributeContext;
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import com.google.testing.junit.testparameterinjector.TestParameterInjector;
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import dev.cel.common.CelAbstractSyntaxTree;
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import org.junit.Test;
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import org.junit.runner.RunWith;
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@RunWith(TestParameterInjector.class)
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public final class Exercise6Test {
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private final Exercise6 exercise6 = new Exercise6();
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@Test
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public void evaluate_constructAttributeContext() {
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// Given JSON web token and the current time as input variables,
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// Setup an expression to construct an AttributeContext protobuf object.
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//
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// Note: the field names within the proto message types are not quoted as they
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// are well-defined names composed of valid identifier characters. Also, note
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// that when building nested proto objects, the message name needs to prefix
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// the object construction.
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String expression =
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"Request{\n"
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+ "auth: Auth{"
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+ " principal: jwt.iss + '/' + jwt.sub,"
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+ " audiences: [jwt.aud],"
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+ " presenter: 'azp' in jwt ? jwt.azp : '',"
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+ " claims: jwt"
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+ "},"
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+ "time: now"
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+ "}";
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// Values for `now` and `jwt` variables to be passed into the runtime
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Timestamp now = Timestamps.now();
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ImmutableMap<String, Object> jwt =
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ImmutableMap.of(
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"sub", "serviceAccount:delegate@acme.co",
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"aud", "my-project",
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"iss", "auth.acme.com:12350",
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"extra_claims", ImmutableMap.of("group", "admin"));
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AttributeContext.Request expectedMessage =
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AttributeContext.Request.newBuilder()
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.setTime(now)
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.setAuth(
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AttributeContext.Auth.newBuilder()
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.setPrincipal("auth.acme.com:12350/serviceAccount:delegate@acme.co")
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.addAudiences("my-project")
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.setClaims(
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Struct.newBuilder()
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.putAllFields(
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ImmutableMap.of(
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"sub", newStringValue("serviceAccount:delegate@acme.co"),
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"aud", newStringValue("my-project"),
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"iss", newStringValue("auth.acme.com:12350")))
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.putFields(
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"extra_claims",
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Value.newBuilder()
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.setStructValue(
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Struct.newBuilder()
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.putFields("group", newStringValue("admin"))
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.build())
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.build())))
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.build();
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// Compile the `Request` message construction expression and validate that
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// the resulting expression type matches the fully qualified message name.
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CelAbstractSyntaxTree ast = exercise6.compile(expression);
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AttributeContext.Request evaluatedResult =
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(AttributeContext.Request)
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exercise6.eval(
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ast,
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ImmutableMap.of(
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"now", now,
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"jwt", jwt));
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assertThat(evaluatedResult).isEqualTo(expectedMessage);
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}
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private static Value newStringValue(String value) {
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return Value.newBuilder().setStringValue(value).build();
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}
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}

‎codelab/src/test/codelab/solutions/BUILD.bazel‎

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"@maven//:junit_junit",
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],
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)
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java_test(
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name = "Exercise6Test",
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srcs = ["Exercise6Test.java"],
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test_class = "codelab.solutions.Exercise6Test",
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deps = [
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"//:java_truth",
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"//codelab:solutions",
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"//common",
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"@maven//:com_google_api_grpc_proto_google_common_protos",
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"@maven//:com_google_guava_guava",
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"@maven//:com_google_protobuf_protobuf_java",
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"@maven//:com_google_protobuf_protobuf_java_util",
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"@maven//:com_google_testparameterinjector_test_parameter_injector",
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"@maven//:junit_junit",
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],
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)

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