Fully implement optional syntax for parser

PiperOrigin-RevId: 572605079

Author: jcking

base/ast_internal/expr.cc

@@ -71,7 +71,8 @@ bool CreateStruct::Entry::operator==(const Entry& other) const {
   } else if (has_map_key() && other.has_map_key()) {
     has_same_key = map_key() == other.map_key();
   }
-  return id_ == other.id_ && has_same_key && value() == other.value();
+  return id_ == other.id_ && has_same_key && value() == other.value() &&
+         optional_entry_ == other.optional_entry();
 }
 
 const Expr& Comprehension::iter_range() const {

base/ast_internal/expr.h

@@ -353,18 +353,30 @@ class CreateList {
  public:
   CreateList() = default;
   explicit CreateList(std::vector<Expr> elements);
+  CreateList(std::vector<Expr> elements, std::vector<int32_t> optional_indices);
 
   void set_elements(std::vector<Expr> elements);
 
   const std::vector<Expr>& elements() const { return elements_; }
 
   std::vector<Expr>& mutable_elements() { return elements_; }
 
+  void set_optional_indices(std::vector<int32_t> optional_indices) {
+    optional_indices_ = std::move(optional_indices);
+  }
+
+  const std::vector<int32_t>& optional_indices() const {
+    return optional_indices_;
+  }
+
+  std::vector<int32_t>& optional_indices() { return optional_indices_; }
+
   bool operator==(const CreateList& other) const;
 
  private:
   // The elements part of the list.
   std::vector<Expr> elements_;
+  std::vector<int32_t> optional_indices_;
 };
 
 // A map or message creation expression.
@@ -379,8 +391,12 @@ class CreateStruct {
    public:
     using KeyKind = absl::variant<std::string, std::unique_ptr<Expr>>;
     Entry() = default;
-    Entry(int64_t id, KeyKind key_kind, std::unique_ptr<Expr> value)
-        : id_(id), key_kind_(std::move(key_kind)), value_(std::move(value)) {}
+    Entry(int64_t id, KeyKind key_kind, std::unique_ptr<Expr> value,
+          bool optional_entry = false)
+        : id_(id),
+          key_kind_(std::move(key_kind)),
+          value_(std::move(value)),
+          optional_entry_(optional_entry) {}
 
     void set_id(int64_t id) { id_ = id; }
 
@@ -437,6 +453,12 @@ class CreateStruct {
       return *value_;
     }
 
+    bool optional_entry() const { return optional_entry_; }
+
+    void set_optional_entry(bool optional_entry) {
+      optional_entry_ = optional_entry;
+    }
+
     bool operator==(const Entry& other) const;
 
     bool operator!=(const Entry& other) const { return !operator==(other); }
@@ -450,6 +472,7 @@ class CreateStruct {
     KeyKind key_kind_;
     // Required. The value assigned to the key.
     std::unique_ptr<Expr> value_;
+    bool optional_entry_ = false;
   };
 
   CreateStruct() = default;
@@ -1602,12 +1625,18 @@ inline void Call::set_args(std::vector<Expr> args) { args_ = std::move(args); }
 inline CreateList::CreateList(std::vector<Expr> elements)
     : elements_(std::move(elements)) {}
 
+inline CreateList::CreateList(std::vector<Expr> elements,
+                              std::vector<int32_t> optional_indices)
+    : elements_(std::move(elements)),
+      optional_indices_(std::move(optional_indices)) {}
+
 inline void CreateList::set_elements(std::vector<Expr> elements) {
   elements_ = std::move(elements);
 }
 
 inline bool CreateList::operator==(const CreateList& other) const {
-  return elements_ == other.elements_;
+  return elements_ == other.elements_ &&
+         optional_indices_ == other.optional_indices_;
 }
 
 inline FunctionType::FunctionType(std::unique_ptr<Type> result_type,

common/operators.cc

@@ -167,6 +167,9 @@ const char* CelOperator::FILTER = "filter";
 const char* CelOperator::NOT_STRICTLY_FALSE = "@not_strictly_false";
 const char* CelOperator::IN = "@in";
 
+const absl::string_view CelOperator::OPT_INDEX = "_[?_]";
+const absl::string_view CelOperator::OPT_SELECT = "_?._";
+
 int LookupPrecedence(const std::string& op) {
   auto precs = Precedences();
   auto p = precs.find(op);

common/operators.h

@@ -44,6 +44,9 @@ struct CelOperator {
   // Named operators, must not have be valid identifiers.
   static const char* NOT_STRICTLY_FALSE;
   static const char* IN;
+
+  static const absl::string_view OPT_INDEX;
+  static const absl::string_view OPT_SELECT;
 };
 
 // These give access to all or some specific precedence value.

extensions/protobuf/ast_converters.cc

@@ -106,6 +106,9 @@ absl::StatusOr<CreateList> ConvertCreateList(
     std::stack<ConversionStackEntry>& stack) {
   CreateList ret_val;
   ret_val.set_elements(std::vector<Expr>(create_list.elements_size()));
+  ret_val.set_optional_indices(
+      std::vector<int32_t>(create_list.optional_indices().begin(),
+                           create_list.optional_indices().end()));
 
   for (int i = 0; i < ret_val.elements().size(); i++) {
     stack.push({&ret_val.mutable_elements()[i], &create_list.elements(i)});
@@ -142,7 +145,7 @@ absl::StatusOr<CreateStruct::Entry> ConvertCreateStructEntry(
         "google::api::expr::v1alpha1::Expr::CreateStruct::Entry missing value");
   }
   CreateStruct::Entry result(entry.id(), std::move(native_key),
-                             std::make_unique<Expr>());
+                             std::make_unique<Expr>(), entry.optional_entry());
   stack.push({&result.mutable_value(), &entry.value()});
 
   return result;

extensions/protobuf/ast_converters_test.cc

@@ -37,6 +37,7 @@ namespace {
 using ::cel::ast_internal::NullValue;
 using ::cel::ast_internal::PrimitiveType;
 using ::cel::ast_internal::WellKnownType;
+using testing::ElementsAreArray;
 using cel::internal::StatusIs;
 
 TEST(AstConvertersTest, IdentToNative) {
@@ -110,6 +111,7 @@ TEST(AstConvertersTest, CreateListToNative) {
         list_expr {
           elements { ident_expr { name: "elem1" } }
           elements { ident_expr { name: "elem2" } }
+          optional_indices: [ 0 ]
         }
       )pb",
       &expr));
@@ -124,6 +126,8 @@ TEST(AstConvertersTest, CreateListToNative) {
   auto& native_elem2 = native_create_list.elements()[1];
   ASSERT_TRUE(native_elem2.has_ident_expr());
   ASSERT_EQ(native_elem2.ident_expr().name(), "elem2");
+  ASSERT_THAT(native_create_list.optional_indices(),
+              ElementsAreArray(expr.list_expr().optional_indices()));
 }
 
 TEST(AstConvertersTest, CreateStructToNative) {
@@ -135,6 +139,7 @@ TEST(AstConvertersTest, CreateStructToNative) {
             id: 1
             field_key: "key1"
             value { ident_expr { name: "value1" } }
+            optional_entry: true
           }
           entries {
             id: 2
@@ -155,6 +160,7 @@ TEST(AstConvertersTest, CreateStructToNative) {
   ASSERT_EQ(native_entry1.field_key(), "key1");
   ASSERT_TRUE(native_entry1.value().has_ident_expr());
   ASSERT_EQ(native_entry1.value().ident_expr().name(), "value1");
+  ASSERT_TRUE(native_entry1.optional_entry());
   auto& native_entry2 = native_struct.entries()[1];
   EXPECT_EQ(native_entry2.id(), 2);
   ASSERT_TRUE(native_entry2.has_map_key());

parser/macro.cc

@@ -14,12 +14,17 @@
 
 #include "parser/macro.h"
 
+#include <cstddef>
 #include <cstdint>
+#include <memory>
 #include <utility>
+#include <vector>
 
 #include "absl/status/status.h"
+#include "absl/status/statusor.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
+#include "absl/strings/string_view.h"
 #include "common/operators.h"
 #include "internal/lexis.h"
 #include "parser/source_factory.h"
@@ -169,4 +174,77 @@ std::vector<Macro> Macro::AllMacros() {
   };
 }
 
+Macro Macro::OptMap() {
+  return Macro(
+      "optMap", 2,
+      [](const std::shared_ptr<SourceFactory>& sf, int64_t macro_id,
+         const Expr& target, const std::vector<Expr>& args) -> Expr {
+        if (args.size() != 2) {
+          return sf->ReportError(args[0].id(), "optMap() requires 2 arguments");
+        }
+        if (!args[0].has_ident_expr()) {
+          return sf->ReportError(
+              args[0].id(),
+              "optMap() variable name must be a simple identifier");
+        }
+        const auto& var_name = args[0].ident_expr().name();
+        const auto& map_expr = args[1];
+
+        std::vector<Expr> call_args;
+        call_args.resize(3);
+        call_args[0] =
+            sf->NewReceiverCallForMacro(macro_id, "hasValue", target, {});
+        auto iter_range = sf->NewListForMacro(macro_id, {});
+        auto accu_init =
+            sf->NewReceiverCallForMacro(macro_id, "value", target, {});
+        auto condition = sf->NewLiteralBoolForMacro(macro_id, false);
+        auto step = sf->NewIdentForMacro(macro_id, var_name);
+        const auto& result = map_expr;
+        auto fold = sf->FoldForMacro(macro_id, "#unused", iter_range, var_name,
+                                     accu_init, condition, step, result);
+        call_args[1] =
+            sf->NewGlobalCallForMacro(macro_id, "optional.of", {fold});
+        call_args[2] = sf->NewGlobalCallForMacro(macro_id, "optional.none", {});
+        return sf->NewGlobalCallForMacro(macro_id, CelOperator::CONDITIONAL,
+                                         call_args);
+      },
+      true);
+}
+
+Macro Macro::OptFlatMap() {
+  return Macro(
+      "optFlatMap", 2,
+      [](const std::shared_ptr<SourceFactory>& sf, int64_t macro_id,
+         const Expr& target, const std::vector<Expr>& args) -> Expr {
+        if (args.size() != 2) {
+          return sf->ReportError(args[0].id(),
+                                 "optFlatMap() requires 2 arguments");
+        }
+        if (!args[0].has_ident_expr()) {
+          return sf->ReportError(
+              args[0].id(),
+              "optFlatMap() variable name must be a simple identifier");
+        }
+        const auto& var_name = args[0].ident_expr().name();
+        const auto& map_expr = args[1];
+        std::vector<Expr> call_args;
+        call_args.resize(3);
+        call_args[0] =
+            sf->NewReceiverCallForMacro(macro_id, "hasValue", target, {});
+        auto iter_range = sf->NewListForMacro(macro_id, {});
+        auto accu_init =
+            sf->NewReceiverCallForMacro(macro_id, "value", target, {});
+        auto condition = sf->NewLiteralBoolForMacro(macro_id, false);
+        auto step = sf->NewIdentForMacro(macro_id, var_name);
+        const auto& result = map_expr;
+        call_args[1] =
+            sf->FoldForMacro(macro_id, "#unused", iter_range, var_name,
+                             accu_init, condition, step, result);
+        call_args[2] = sf->NewGlobalCallForMacro(macro_id, "optional.none", {});
+        return sf->NewGlobalCallForMacro(macro_id, CelOperator::CONDITIONAL,
+                                         call_args);
+      },
+      true);
+}
+
 }  // namespace cel

parser/macro.h

@@ -123,6 +123,10 @@ class Macro final {
 
   static std::vector<Macro> AllMacros();
 
+  static Macro OptMap();
+
+  static Macro OptFlatMap();
+
  private:
   std::string key_;
   size_t arg_count_;

parser/options.h

@@ -44,6 +44,9 @@ struct ParserOptions final {
 
   // Add macro calls to macro_calls list in source_info.
   bool add_macro_calls = ::cel_parser_internal::kDefaultAddMacroCalls;
+
+  // Enable support for optional syntax.
+  bool enable_optional_syntax = false;
 };
 
 }  // namespace cel