Switch to dev.cel:cel (#303)

Switch to Google's CEL implementation.
-------
Signed-off-by: Sri Krishna <[email protected]>
Co-authored-by: Steve Ayers <[email protected]>

Author: srikrsna-buf

build.gradle.kts

@@ -339,12 +339,12 @@ dependencies {
     annotationProcessor(libs.nullaway)
     api(libs.jspecify)
     api(libs.protobuf.java)
-    implementation(enforcedPlatform(libs.cel))
-    implementation(libs.cel.core)
+    implementation(libs.cel)
 
     buf("build.buf:buf:${libs.versions.buf.get()}:${osdetector.classifier}@exe")
 
     testImplementation(libs.assertj)
+    testImplementation(libs.grpc.protobuf)
     testImplementation(platform(libs.junit.bom))
     testImplementation("org.junit.jupiter:junit-jupiter")
     testRuntimeOnly("org.junit.platform:junit-platform-launcher")

conformance/expected-failures.yaml

@@ -0,0 +1,9 @@
+standard_rules/bytes:
+  - pattern/invalid/not_utf8
+#        input: [ type.googleapis.com/buf.validate.conformance.cases.BytesPattern ]:{val:"\x99"}
+#        want: runtime error: value must be valid UTF-8 to apply regexp
+#        got: validation error (1 violation)
+#         1. rule_id: "bytes.pattern"
+#           message: "value must match regex pattern `^[\\x00-\\x7F]+$`"
+#           field: "val" elements:{field_number:1 field_name:"val" field_type:TYPE_BYTES}
+#           rule: "bytes.pattern" elements:{field_number:15 field_name:"bytes" field_type:TYPE_MESSAGE} elements:{field_number:4 field_name:"pattern" field_type:TYPE_STRING}

gradle/libs.versions.toml

@@ -1,7 +1,7 @@
 [versions]
 assertj = "3.27.3"
 buf = "1.54.0"
-cel = "0.5.3"
+cel = "0.9.1"
 error-prone = "2.38.0"
 junit = "5.13.0"
 maven-publish = "0.32.0"
@@ -10,10 +10,10 @@ protobuf = "4.31.1"
 [libraries]
 assertj = { module = "org.assertj:assertj-core", version.ref = "assertj" }
 buf = { module = "build.buf:buf", version.ref = "buf" }
-cel = { module = "org.projectnessie.cel:cel-bom", version.ref = "cel" }
-cel-core = { module = "org.projectnessie.cel:cel-core" }
+cel = { module = "dev.cel:cel", version.ref = "cel" }
 errorprone-annotations = { module = "com.google.errorprone:error_prone_annotations", version.ref = "error-prone" }
 errorprone-core = { module = "com.google.errorprone:error_prone_core", version.ref = "error-prone" }
+grpc-protobuf = { module = "io.grpc:grpc-protobuf", version = "1.73.0" }
 jspecify = { module ="org.jspecify:jspecify", version = "1.0.0" }
 junit-bom = { module = "org.junit:junit-bom", version.ref = "junit" }
 maven-plugin = { module = "com.vanniktech:gradle-maven-publish-plugin", version.ref = "maven-publish" }

src/main/java/build/buf/protovalidate/AstExpression.java

@@ -15,46 +15,55 @@
 package build.buf.protovalidate;
 
 import build.buf.protovalidate.exceptions.CompilationException;
-import com.google.api.expr.v1alpha1.Type;
-import org.projectnessie.cel.Ast;
-import org.projectnessie.cel.Env;
+import dev.cel.common.CelAbstractSyntaxTree;
+import dev.cel.common.CelValidationException;
+import dev.cel.common.CelValidationResult;
+import dev.cel.common.types.CelKind;
+import dev.cel.compiler.CelCompiler;
 
-/** {@link AstExpression} is a compiled CEL {@link Ast}. */
+/** {@link AstExpression} is a compiled CEL {@link CelAbstractSyntaxTree}. */
 class AstExpression {
   /** The compiled CEL AST. */
-  public final Ast ast;
+  public final CelAbstractSyntaxTree ast;
 
   /** Contains the original expression from the proto file. */
   public final Expression source;
 
   /** Constructs a new {@link AstExpression}. */
-  private AstExpression(Ast ast, Expression source) {
+  private AstExpression(CelAbstractSyntaxTree ast, Expression source) {
     this.ast = ast;
     this.source = source;
   }
 
   /**
    * Compiles the given expression to a {@link AstExpression}.
    *
-   * @param env The CEL environment.
+   * @param cel The CEL compiler.
    * @param expr The expression to compile.
    * @return The compiled {@link AstExpression}.
    * @throws CompilationException if the expression compilation fails.
    */
-  public static AstExpression newAstExpression(Env env, Expression expr)
+  public static AstExpression newAstExpression(CelCompiler cel, Expression expr)
       throws CompilationException {
-    Env.AstIssuesTuple astIssuesTuple = env.compile(expr.expression);
-    if (astIssuesTuple.hasIssues()) {
+    CelValidationResult compileResult = cel.compile(expr.expression);
+    if (!compileResult.getAllIssues().isEmpty()) {
       throw new CompilationException(
-          "Failed to compile expression " + expr.id + ":\n" + astIssuesTuple.getIssues());
+          "Failed to compile expression " + expr.id + ":\n" + compileResult.getIssueString());
     }
-    Ast ast = astIssuesTuple.getAst();
-    Type outType = ast.getResultType();
-    if (outType.getPrimitive() != Type.PrimitiveType.BOOL
-        && outType.getPrimitive() != Type.PrimitiveType.STRING) {
+    CelAbstractSyntaxTree ast;
+    try {
+      ast = compileResult.getAst();
+    } catch (CelValidationException e) {
+      // This will not happen as we checked for issues, and it only throws when
+      // it has at least one issue of error severity.
+      throw new CompilationException(
+          "Failed to compile expression " + expr.id + ":\n" + compileResult.getIssueString());
+    }
+    CelKind outKind = ast.getResultType().kind();
+    if (outKind != CelKind.BOOL && outKind != CelKind.STRING) {
       throw new CompilationException(
           String.format(
-              "Expression outputs, wanted either bool or string: %s %s", expr.id, outType));
+              "Expression outputs, wanted either bool or string: %s %s", expr.id, outKind));
     }
     return new AstExpression(ast, expr);
   }

src/main/java/build/buf/protovalidate/CelPrograms.java

@@ -15,6 +15,7 @@
 package build.buf.protovalidate;
 
 import build.buf.protovalidate.exceptions.ExecutionException;
+import dev.cel.runtime.CelVariableResolver;
 import java.util.ArrayList;
 import java.util.List;
 import org.jspecify.annotations.Nullable;
@@ -44,10 +45,10 @@ public boolean tautology() {
   @Override
   public List<RuleViolation.Builder> evaluate(Value val, boolean failFast)
       throws ExecutionException {
-    Variable activation = Variable.newThisVariable(val.value(Object.class));
+    CelVariableResolver bindings = Variable.newThisVariable(val.value(Object.class));
     List<RuleViolation.Builder> violations = new ArrayList<>();
     for (CompiledProgram program : programs) {
-      RuleViolation.Builder violation = program.eval(val, activation);
+      RuleViolation.Builder violation = program.eval(val, bindings);
       if (violation != null) {
         violations.add(violation);
         if (failFast) {

src/main/java/build/buf/protovalidate/CompiledProgram.java

@@ -16,10 +16,10 @@
 
 import build.buf.protovalidate.exceptions.ExecutionException;
 import build.buf.validate.FieldPath;
+import dev.cel.runtime.CelEvaluationException;
+import dev.cel.runtime.CelRuntime.Program;
+import dev.cel.runtime.CelVariableResolver;
 import org.jspecify.annotations.Nullable;
-import org.projectnessie.cel.Program;
-import org.projectnessie.cel.common.types.Err;
-import org.projectnessie.cel.common.types.ref.Val;
 
 /**
  * {@link CompiledProgram} is a parsed and type-checked {@link Program} along with the source {@link
@@ -38,6 +38,12 @@ class CompiledProgram {
   /** The rule value. */
   @Nullable private final Value ruleValue;
 
+  /**
+   * Global variables to pass to the evaluation step. Program/CelRuntime doesn't have a concept of
+   * global variables.
+   */
+  @Nullable private final CelVariableResolver globals;
+
   /**
    * Constructs a new {@link CompiledProgram}.
    *
@@ -47,30 +53,38 @@ class CompiledProgram {
    * @param ruleValue The rule value.
    */
   public CompiledProgram(
-      Program program, Expression source, @Nullable FieldPath rulePath, @Nullable Value ruleValue) {
+      Program program,
+      Expression source,
+      @Nullable FieldPath rulePath,
+      @Nullable Value ruleValue,
+      @Nullable CelVariableResolver globals) {
     this.program = program;
     this.source = source;
     this.rulePath = rulePath;
     this.ruleValue = ruleValue;
+    this.globals = globals;
   }
 
   /**
-   * Evaluate the compiled program with a given set of {@link Variable} bindings.
+   * Evaluate the compiled program with a given set of {@link Variable} variables.
    *
-   * @param bindings Variable bindings used for the evaluation.
+   * @param variables Variables used for the evaluation.
    * @param fieldValue Field value to return in violations.
    * @return The {@link build.buf.validate.Violation} from the evaluation, or null if there are no
    *     violations.
    * @throws ExecutionException If the evaluation of the CEL program fails with an error.
    */
-  public RuleViolation.@Nullable Builder eval(Value fieldValue, Variable bindings)
+  public RuleViolation.@Nullable Builder eval(Value fieldValue, CelVariableResolver variables)
       throws ExecutionException {
-    Program.EvalResult evalResult = program.eval(bindings);
-    Val val = evalResult.getVal();
-    if (val instanceof Err) {
-      throw new ExecutionException(String.format("error evaluating %s: %s", source.id, val));
+    Object value;
+    try {
+      if (this.globals != null) {
+        variables = CelVariableResolver.hierarchicalVariableResolver(variables, this.globals);
+      }
+      value = program.eval(variables);
+    } catch (CelEvaluationException e) {
+      throw new ExecutionException(String.format("error evaluating %s: %s", source.id, e));
     }
-    Object value = val.value();
     if (value instanceof String) {
       if ("".equals(value)) {
         return null;
@@ -88,7 +102,7 @@ public CompiledProgram(
       }
       return builder;
     } else if (value instanceof Boolean) {
-      if (val.booleanValue()) {
+      if (Boolean.TRUE.equals(value)) {
         return null;
       }
       RuleViolation.Builder builder =
@@ -101,7 +115,7 @@ public CompiledProgram(
       }
       return builder;
     } else {
-      throw new ExecutionException(String.format("resolved to an unexpected type %s", val));
+      throw new ExecutionException(String.format("resolved to an unexpected type %s", value));
     }
   }
 }