Implement parts of cel.@block in C++ evaluator

bazel/deps.bzl

@@ -141,10 +141,10 @@ def cel_spec_deps():
         url = "https://github.com/bazelbuild/rules_python/releases/download/0.33.2/rules_python-0.33.2.tar.gz",
     )
 
-    CEL_SPEC_GIT_SHA = "5299974f1c69103e4bb4eec48f7d9b24413ca3c7"  # Jul 19, 2024
+    CEL_SPEC_GIT_SHA = "5ed294fa64206016a37db2986dab942c80a65e4b"  # Aug 16, 2024
     http_archive(
         name = "com_google_cel_spec",
-        sha256 = "2beb97d2d8fff4db659f0633d0e432fdb7d328fe9c39061eb142af5dbb6eaea0",
+        sha256 = "926abf84cde8c05ce99700caee5786bc7d8aeec77185fd669bce27df455a1215",
         strip_prefix = "cel-spec-" + CEL_SPEC_GIT_SHA,
         urls = ["https://github.com/google/cel-spec/archive/" + CEL_SPEC_GIT_SHA + ".zip"],
     )

conformance/BUILD

@@ -45,6 +45,7 @@ cc_library(
     hdrs = ["service.h"],
     deps = [
         ":value_conversion",
+        "//common:expr",
         "//common:memory",
         "//common:source",
         "//common:value",
@@ -67,6 +68,8 @@ cc_library(
         "//extensions/protobuf:value",
         "//internal:status_macros",
         "//parser",
+        "//parser:macro",
+        "//parser:macro_expr_factory",
         "//parser:macro_registry",
         "//parser:options",
         "//parser:standard_macros",
@@ -82,6 +85,8 @@ cc_library(
         "@com_google_absl//absl/status",
         "@com_google_absl//absl/status:statusor",
         "@com_google_absl//absl/strings",
+        "@com_google_absl//absl/types:optional",
+        "@com_google_absl//absl/types:span",
         "@com_google_cel_spec//proto/test/v1/proto2:test_all_types_cc_proto",
         "@com_google_cel_spec//proto/test/v1/proto3:test_all_types_cc_proto",
         "@com_google_googleapis//google/api/expr/conformance/v1alpha1:conformance_cc_proto",
@@ -141,6 +146,7 @@ _ALL_TESTS = [
     "@com_google_cel_spec//tests/simple:testdata/timestamps.textproto",
     "@com_google_cel_spec//tests/simple:testdata/unknowns.textproto",
     "@com_google_cel_spec//tests/simple:testdata/wrappers.textproto",
+    "@com_google_cel_spec//tests/simple:testdata/block_ext.textproto",
 ]
 
 _TESTS_TO_SKIP_MODERN = [
@@ -209,6 +215,13 @@ _TESTS_TO_SKIP_MODERN = [
 
     # TODO: Add missing conversion function
     "conversions/bool",
+
+    # cel.@block
+    "block_ext/basic/multiple_macros_1",
+    "block_ext/basic/multiple_macros_2",
+    "block_ext/basic/multiple_macros_3",
+    "block_ext/basic/nested_macros",
+    "block_ext/basic/nested_macros_2",
 ]
 
 _TESTS_TO_SKIP_MODERN_DASHBOARD = [
@@ -276,6 +289,17 @@ _TESTS_TO_SKIP_LEGACY = [
 
     # TODO: Add missing conversion function
     "conversions/bool",
+
+    # cel.@block
+    "block_ext/basic/optional_list",
+    "block_ext/basic/optional_map",
+    "block_ext/basic/optional_map_chained",
+    "block_ext/basic/optional_message",
+    "block_ext/basic/multiple_macros_1",
+    "block_ext/basic/multiple_macros_2",
+    "block_ext/basic/multiple_macros_3",
+    "block_ext/basic/nested_macros",
+    "block_ext/basic/nested_macros_2",
 ]
 
 _TESTS_TO_SKIP_LEGACY_DASHBOARD = [

conformance/service.cc

@@ -14,6 +14,7 @@
 
 #include "conformance/service.h"
 
+#include <cstdint>
 #include <iostream>
 #include <memory>
 #include <string>
@@ -33,7 +34,11 @@
 #include "absl/memory/memory.h"
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
+#include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
+#include "absl/types/optional.h"
+#include "absl/types/span.h"
+#include "common/expr.h"
 #include "common/memory.h"
 #include "common/source.h"
 #include "common/value.h"
@@ -56,6 +61,8 @@
 #include "extensions/protobuf/type_reflector.h"
 #include "extensions/strings.h"
 #include "internal/status_macros.h"
+#include "parser/macro.h"
+#include "parser/macro_expr_factory.h"
 #include "parser/macro_registry.h"
 #include "parser/options.h"
 #include "parser/parser.h"
@@ -90,6 +97,103 @@ namespace google::api::expr::runtime {
 
 namespace {
 
+bool IsCelNamespace(const cel::Expr& target) {
+  return target.has_ident_expr() && target.ident_expr().name() == "cel";
+}
+
+absl::optional<cel::Expr> CelBlockMacroExpander(cel::MacroExprFactory& factory,
+                                                cel::Expr& target,
+                                                absl::Span<cel::Expr> args) {
+  if (!IsCelNamespace(target)) {
+    return absl::nullopt;
+  }
+  cel::Expr& bindings_arg = args[0];
+  if (!bindings_arg.has_list_expr()) {
+    return factory.ReportErrorAt(
+        bindings_arg, "cel.block requires the first arg to be a list literal");
+  }
+  return factory.NewCall("cel.@block", args);
+}
+
+absl::optional<cel::Expr> CelIndexMacroExpander(cel::MacroExprFactory& factory,
+                                                cel::Expr& target,
+                                                absl::Span<cel::Expr> args) {
+  if (!IsCelNamespace(target)) {
+    return absl::nullopt;
+  }
+  cel::Expr& index_arg = args[0];
+  if (!index_arg.has_const_expr() || !index_arg.const_expr().has_int_value()) {
+    return factory.ReportErrorAt(
+        index_arg, "cel.index requires a single non-negative int constant arg");
+  }
+  int64_t index = index_arg.const_expr().int_value();
+  if (index < 0) {
+    return factory.ReportErrorAt(
+        index_arg, "cel.index requires a single non-negative int constant arg");
+  }
+  return factory.NewIdent(absl::StrCat("@index", index));
+}
+
+absl::optional<cel::Expr> CelIterVarMacroExpander(
+    cel::MacroExprFactory& factory, cel::Expr& target,
+    absl::Span<cel::Expr> args) {
+  if (!IsCelNamespace(target)) {
+    return absl::nullopt;
+  }
+  cel::Expr& index_arg = args[0];
+  if (!index_arg.has_const_expr() || !index_arg.const_expr().has_int_value()) {
+    return factory.ReportErrorAt(
+        index_arg,
+        "cel.iterVar requires a single non-negative int constant arg");
+  }
+  int64_t index = index_arg.const_expr().int_value();
+  if (index < 0) {
+    return factory.ReportErrorAt(
+        index_arg,
+        "cel.iterVar requires a single non-negative int constant arg");
+  }
+  return factory.NewIdent(absl::StrCat("@c:", index));
+}
+
+absl::optional<cel::Expr> CelAccuVarMacroExpander(
+    cel::MacroExprFactory& factory, cel::Expr& target,
+    absl::Span<cel::Expr> args) {
+  if (!IsCelNamespace(target)) {
+    return absl::nullopt;
+  }
+  cel::Expr& index_arg = args[0];
+  if (!index_arg.has_const_expr() || !index_arg.const_expr().has_int_value()) {
+    return factory.ReportErrorAt(
+        index_arg,
+        "cel.accuVar requires a single non-negative int constant arg");
+  }
+  int64_t index = index_arg.const_expr().int_value();
+  if (index < 0) {
+    return factory.ReportErrorAt(
+        index_arg,
+        "cel.accuVar requires a single non-negative int constant arg");
+  }
+  return factory.NewIdent(absl::StrCat("@x:", index));
+}
+
+absl::Status RegisterCelBlockMacros(cel::MacroRegistry& registry) {
+  CEL_ASSIGN_OR_RETURN(auto block_macro,
+                       cel::Macro::Receiver("block", 2, CelBlockMacroExpander));
+  CEL_RETURN_IF_ERROR(registry.RegisterMacro(block_macro));
+  CEL_ASSIGN_OR_RETURN(auto index_macro,
+                       cel::Macro::Receiver("index", 1, CelIndexMacroExpander));
+  CEL_RETURN_IF_ERROR(registry.RegisterMacro(index_macro));
+  CEL_ASSIGN_OR_RETURN(
+      auto iter_var_macro,
+      cel::Macro::Receiver("iterVar", 1, CelIterVarMacroExpander));
+  CEL_RETURN_IF_ERROR(registry.RegisterMacro(iter_var_macro));
+  CEL_ASSIGN_OR_RETURN(
+      auto accu_var_macro,
+      cel::Macro::Receiver("accuVar", 1, CelAccuVarMacroExpander));
+  CEL_RETURN_IF_ERROR(registry.RegisterMacro(accu_var_macro));
+  return absl::OkStatus();
+}
+
 google::rpc::Code ToGrpcCode(absl::StatusCode code) {
   return static_cast<google::rpc::Code>(code);
 }
@@ -126,6 +230,7 @@ absl::Status LegacyParse(const conformance::v1alpha1::ParseRequest& request,
   CEL_RETURN_IF_ERROR(cel::extensions::RegisterBindingsMacros(macros, options));
   CEL_RETURN_IF_ERROR(cel::extensions::RegisterMathMacros(macros, options));
   CEL_RETURN_IF_ERROR(cel::extensions::RegisterProtoMacros(macros, options));
+  CEL_RETURN_IF_ERROR(RegisterCelBlockMacros(macros));
   CEL_ASSIGN_OR_RETURN(auto source, cel::NewSource(request.cel_source(),
                                                    request.source_location()));
   CEL_ASSIGN_OR_RETURN(auto parsed_expr,

eval/compiler/BUILD

@@ -129,6 +129,7 @@ cc_library(
         "@com_google_absl//absl/container:flat_hash_set",
         "@com_google_absl//absl/container:node_hash_map",
         "@com_google_absl//absl/log:absl_check",
+        "@com_google_absl//absl/log:absl_log",
         "@com_google_absl//absl/log:check",
         "@com_google_absl//absl/status",
         "@com_google_absl//absl/status:statusor",