Include identity functions in the standard definitions

PiperOrigin-RevId: 657756541

Author: l46kok

base/builtins.h

@@ -81,7 +81,7 @@ constexpr char kSeconds[] = "getSeconds";
 constexpr char kMilliseconds[] = "getMilliseconds";
 
 // Type conversions
-// TODO: Add other type conversion methods.
+constexpr char kBool[] = "bool";
 constexpr char kBytes[] = "bytes";
 constexpr char kDouble[] = "double";
 constexpr char kDyn[] = "dyn";

runtime/standard/type_conversion_functions.cc

@@ -42,6 +42,13 @@ using ::cel::internal::MaxTimestamp;
 // Time representing `9999-12-31T23:59:59.999999999Z`.
 const absl::Time kMaxTime = MaxTimestamp();
 
+absl::Status RegisterBoolConversionFunctions(FunctionRegistry& registry,
+                                             const RuntimeOptions&) {
+  // bool -> bool
+  return UnaryFunctionAdapter<bool, bool>::RegisterGlobalOverload(
+      cel::builtin::kBool, [](ValueManager&, bool v) { return v; }, registry);
+}
+
 absl::Status RegisterIntConversionFunctions(FunctionRegistry& registry,
                                             const RuntimeOptions&) {
   // bool -> int
@@ -362,6 +369,8 @@ absl::Status RegisterTimeConversionFunctions(FunctionRegistry& registry,
 
 absl::Status RegisterTypeConversionFunctions(FunctionRegistry& registry,
                                              const RuntimeOptions& options) {
+  CEL_RETURN_IF_ERROR(RegisterBoolConversionFunctions(registry, options));
+
   CEL_RETURN_IF_ERROR(RegisterBytesConversionFunctions(registry, options));
 
   CEL_RETURN_IF_ERROR(RegisterDoubleConversionFunctions(registry, options));

runtime/standard/type_conversion_functions_test.cc

@@ -33,6 +33,17 @@ MATCHER_P3(MatchesUnaryDescriptor, name, receiver, expected_kind, "") {
          descriptor.types() == types;
 }
 
+TEST(RegisterTypeConversionFunctions, RegisterBoolConversionFunctions) {
+  FunctionRegistry registry;
+  RuntimeOptions options;
+
+  ASSERT_OK(RegisterTypeConversionFunctions(registry, options));
+
+  EXPECT_THAT(registry.FindStaticOverloads(builtin::kBool, false, {Kind::kAny}),
+              UnorderedElementsAre(
+                  MatchesUnaryDescriptor(builtin::kBool, false, Kind::kBool)));
+}
+
 TEST(RegisterTypeConversionFunctions, RegisterIntConversionFunctions) {
   FunctionRegistry registry;
   RuntimeOptions options;