Update the "strings" extension to be compatible with CelEnvironmentExporter

PiperOrigin-RevId: 789175046

Author: dmitriplotnikov

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

@@ -119,7 +119,8 @@ public Builder addStandardExtensions(CelOptions options) {
           CelExtensions.getExtensionLibrary("math", options),
           CelExtensions.getExtensionLibrary("protos", options),
           CelExtensions.getExtensionLibrary("regex", options),
-          CelExtensions.getExtensionLibrary("sets", options));
+          CelExtensions.getExtensionLibrary("sets", options),
+          CelExtensions.getExtensionLibrary("strings", options));
       // TODO: add support for remaining standard extensions
       return this;
     }

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

@@ -85,6 +85,7 @@ java_library(
         "//common/internal",
         "//common/types",
         "//compiler:compiler_builder",
+        "//extensions:extension_library",
         "//runtime",
         "//runtime:evaluation_exception_builder",
         "//runtime:function_binding",

extensions/src/main/java/dev/cel/extensions/CelExtensions.java

@@ -317,6 +317,8 @@ public static CelExtensionLibrary<? extends CelExtensionLibrary.FeatureSet> getE
         return CelRegexExtensions.library();
       case "sets":
         return CelSetsExtensions.library(options);
+      case "strings":
+        return CelStringExtensions.library();
       // TODO: add support for remaining standard extensions
       default:
         throw new IllegalArgumentException("Unknown standard extension '" + name + "'");

extensions/src/main/java/dev/cel/extensions/CelStringExtensions.java

@@ -14,6 +14,7 @@
 
 package dev.cel.extensions;
 
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
 import static java.lang.Math.max;
 import static java.lang.Math.min;
 
@@ -42,7 +43,8 @@
 
 /** Internal implementation of CEL string extensions. */
 @Immutable
-public final class CelStringExtensions implements CelCompilerLibrary, CelRuntimeLibrary {
+public final class CelStringExtensions
+    implements CelCompilerLibrary, CelRuntimeLibrary, CelExtensionLibrary.FeatureSet {
 
   /** Denotes the string extension function */
   @SuppressWarnings({"unchecked"}) // Unchecked: Type-checker guarantees casting safety.
@@ -250,6 +252,35 @@ String getFunction() {
     this.functions = ImmutableSet.copyOf(functions);
   }
 
+  private static final CelExtensionLibrary<CelStringExtensions> LIBRARY =
+      new CelExtensionLibrary<CelStringExtensions>() {
+        private final CelStringExtensions version0 = new CelStringExtensions();
+
+        @Override
+        public String name() {
+          return "strings";
+        }
+
+        @Override
+        public ImmutableSet<CelStringExtensions> versions() {
+          return ImmutableSet.of(version0);
+        }
+      };
+
+  static CelExtensionLibrary<CelStringExtensions> library() {
+    return LIBRARY;
+  }
+
+  @Override
+  public int version() {
+    return 0;
+  }
+
+  @Override
+  public ImmutableSet<CelFunctionDecl> functions() {
+    return functions.stream().map(f -> f.functionDecl).collect(toImmutableSet());
+  }
+
   @Override
   public void setCheckerOptions(CelCheckerBuilder checkerBuilder) {
     functions.forEach(function -> checkerBuilder.addFunctionDeclarations(function.functionDecl));

extensions/src/test/java/dev/cel/extensions/CelStringExtensionsTest.java

@@ -23,6 +23,8 @@
 import com.google.testing.junit.testparameterinjector.TestParameterInjector;
 import com.google.testing.junit.testparameterinjector.TestParameters;
 import dev.cel.common.CelAbstractSyntaxTree;
+import dev.cel.common.CelFunctionDecl;
+import dev.cel.common.CelOptions;
 import dev.cel.common.CelValidationException;
 import dev.cel.common.types.SimpleType;
 import dev.cel.compiler.CelCompiler;
@@ -54,6 +56,27 @@ public final class CelStringExtensionsTest {
   private static final CelRuntime RUNTIME =
       CelRuntimeFactory.standardCelRuntimeBuilder().addLibraries(CelExtensions.strings()).build();
 
+  @Test
+  public void library() {
+    CelExtensionLibrary<?> library =
+        CelExtensions.getExtensionLibrary("strings", CelOptions.DEFAULT);
+    assertThat(library.name()).isEqualTo("strings");
+    assertThat(library.latest().version()).isEqualTo(0);
+    assertThat(library.version(0).functions().stream().map(CelFunctionDecl::name))
+        .containsExactly(
+            "charAt",
+            "indexOf",
+            "join",
+            "lastIndexOf",
+            "lowerAscii",
+            "replace",
+            "split",
+            "substring",
+            "trim",
+            "upperAscii");
+    assertThat(library.version(0).macros()).isEmpty();
+  }
+
   @Test
   @TestParameters("{string: 'abcd', beginIndex: 0, expectedResult: 'abcd'}")
   @TestParameters("{string: 'abcd', beginIndex: 1, expectedResult: 'bcd'}")