protos_generator/gen_accessors.cc - third_party/protobuf - Git at Google

 // Protocol Buffers - Google's data interchange format
 // Copyright 2023 Google LLC.  All rights reserved.
 //
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd

 #include "protos_generator/gen_accessors.h"

 #include <string>

 #include "absl/container/flat_hash_set.h"
 #include "absl/strings/match.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
 #include "google/protobuf/descriptor.h"
 #include "protos_generator/gen_repeated_fields.h"
 #include "protos_generator/gen_utils.h"
 #include "protos_generator/names.h"
 #include "protos_generator/output.h"
 #include "upb_generator/common.h"
 #include "upb_generator/keywords.h"
 #include "upb_generator/names.h"

 namespace protos_generator {

 namespace protobuf = ::google::protobuf;

 using NameToFieldDescriptorMap =
     absl::flat_hash_map<absl::string_view, const protobuf::FieldDescriptor*>;

 void WriteFieldAccessorHazzer(const protobuf::Descriptor* desc,
                               const protobuf::FieldDescriptor* field,
                               absl::string_view resolved_field_name,
                               absl::string_view resolved_upbc_name,
                               Output& output);
 void WriteFieldAccessorClear(const protobuf::Descriptor* desc,
                              const protobuf::FieldDescriptor* field,
                              absl::string_view resolved_field_name,
                              absl::string_view resolved_upbc_name,
                              Output& output);
 void WriteMapFieldAccessors(const protobuf::Descriptor* desc,
                             const protobuf::FieldDescriptor* field,
                             absl::string_view resolved_field_name,
                             absl::string_view resolved_upbc_name,
                             Output& output);

 void WriteMapAccessorDefinitions(const protobuf::Descriptor* message,
                                  const protobuf::FieldDescriptor* field,
                                  absl::string_view resolved_field_name,
                                  absl::string_view class_name, Output& output);

 // Returns C++ class member name by resolving naming conflicts across
 // proto field names (such as clear_ prefixes) and keyword collisions.
 //
 // The Upb C generator prefixes all accessors with package and class names
 // avoiding collisions. Therefore we need to use raw field names when calling
 // into C accessors but need to fully resolve conflicts for C++ class members.
 std::string ResolveFieldName(const protobuf::FieldDescriptor* field,
                              const NameToFieldDescriptorMap& field_names);

 NameToFieldDescriptorMap CreateFieldNameMap(
     const protobuf::Descriptor* message) {
   NameToFieldDescriptorMap field_names;
   for (int i = 0; i < message->field_count(); i++) {
     const protobuf::FieldDescriptor* field = message->field(i);
     field_names.emplace(field->name(), field);
   }
   return field_names;
 }

 void WriteFieldAccessorsInHeader(const protobuf::Descriptor* desc,
                                  Output& output) {
   // Generate const methods.
   OutputIndenter i(output);

   auto field_names = CreateFieldNameMap(desc);
   auto upbc_field_names = upb::generator::CreateFieldNameMap(desc);

   for (const auto* field : FieldNumberOrder(desc)) {
     std::string resolved_field_name = ResolveFieldName(field, field_names);
     std::string resolved_upbc_name =
         upb::generator::ResolveFieldName(field, upbc_field_names);
     WriteFieldAccessorHazzer(desc, field, resolved_field_name,
                              resolved_upbc_name, output);
     WriteFieldAccessorClear(desc, field, resolved_field_name,
                             resolved_upbc_name, output);

     if (field->is_map()) {
       WriteMapFieldAccessors(desc, field, resolved_field_name,
                              resolved_upbc_name, output);
     } else if (desc->options().map_entry()) {
       // TODO Implement map entry
     } else if (field->is_repeated()) {
       WriteRepeatedFieldsInMessageHeader(desc, field, resolved_field_name,
                                          resolved_upbc_name, output);
     } else {
       // non-repeated.
       if (field->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_STRING) {
         output(R"cc(
                  $0 $1() const;
                  void set_$1($0 value);
                )cc",
                CppConstType(field), resolved_field_name);
       } else if (field->cpp_type() ==
                  protobuf::FieldDescriptor::CPPTYPE_MESSAGE) {
         output(R"cc(
                  $1 $2() const;
                  $0 mutable_$2();
                )cc",
                MessagePtrConstType(field, /* const */ false),
                MessagePtrConstType(field, /* const */ true),
                resolved_field_name, resolved_upbc_name);
       } else {
         output(
             R"cc(
               inline $0 $1() const { return $2_$3(msg_); }
               inline void set_$1($0 value) { return $2_set_$3(msg_, value); }
             )cc",
             CppConstType(field), resolved_field_name, MessageName(desc),
             resolved_upbc_name);
       }
     }
   }
 }

 void WriteFieldAccessorHazzer(const protobuf::Descriptor* desc,
                               const protobuf::FieldDescriptor* field,
                               const absl::string_view resolved_field_name,
                               const absl::string_view resolved_upbc_name,
                               Output& output) {
   // Generate hazzer (if any).
   if (field->has_presence()) {
     // Has presence.
     output("inline bool has_$0() const { return $1_has_$2(msg_); }\n",
            resolved_field_name, MessageName(desc), resolved_upbc_name);
   }
 }

 void WriteFieldAccessorClear(const protobuf::Descriptor* desc,
                              const protobuf::FieldDescriptor* field,
                              const absl::string_view resolved_field_name,
                              const absl::string_view resolved_upbc_name,
                              Output& output) {
   if (field->has_presence()) {
     output("void clear_$0() { $2_clear_$1(msg_); }\n", resolved_field_name,
            resolved_upbc_name, MessageName(desc));
   }
 }

 void WriteMapFieldAccessors(const protobuf::Descriptor* desc,
                             const protobuf::FieldDescriptor* field,
                             const absl::string_view resolved_field_name,
                             const absl::string_view resolved_upbc_name,
                             Output& output) {
   const protobuf::Descriptor* entry = field->message_type();
   const protobuf::FieldDescriptor* key = entry->FindFieldByNumber(1);
   const protobuf::FieldDescriptor* val = entry->FindFieldByNumber(2);
   output(
       R"cc(
         inline size_t $0_size() const { return $1_$3_size(msg_); }
         inline void clear_$0() { $1_clear_$3(msg_); }
         void delete_$0($2 key);
       )cc",
       resolved_field_name, MessageName(desc), CppConstType(key),
       resolved_upbc_name);

   if (val->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_MESSAGE) {
     output(
         R"cc(
           bool set_$0($1 key, $3 value);
           bool set_$0($1 key, $4 value);
           absl::StatusOr<$3> get_$0($1 key);
         )cc",
         resolved_field_name, CppConstType(key), CppConstType(val),
         MessagePtrConstType(val, /* is_const */ true),
         MessagePtrConstType(val, /* is_const */ false));
   } else {
     output(
         R"cc(
           bool set_$0($1 key, $2 value);
           absl::StatusOr<$2> get_$0($1 key);
         )cc",
         resolved_field_name, CppConstType(key), CppConstType(val));
   }
 }

 void WriteAccessorsInSource(const protobuf::Descriptor* desc, Output& output) {
   std::string class_name = ClassName(desc);
   absl::StrAppend(&class_name, "Access");
   output("namespace internal {\n");
   const char arena_expression[] = "arena_";
   auto field_names = CreateFieldNameMap(desc);
   auto upbc_field_names = upb::generator::CreateFieldNameMap(desc);

   // Generate const methods.
   OutputIndenter i(output);
   for (const auto* field : FieldNumberOrder(desc)) {
     std::string resolved_field_name = ResolveFieldName(field, field_names);
     std::string resolved_upbc_name =
         upb::generator::ResolveFieldName(field, upbc_field_names);
     if (field->is_map()) {
       WriteMapAccessorDefinitions(desc, field, resolved_field_name, class_name,
                                   output);
     } else if (desc->options().map_entry()) {
       // TODO Implement map entry
     } else if (field->is_repeated()) {
       if (field->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_MESSAGE) {
         WriteRepeatedMessageAccessor(desc, field, resolved_field_name,
                                      class_name, output);
       } else if (field->cpp_type() ==
                  protobuf::FieldDescriptor::CPPTYPE_STRING) {
         WriteRepeatedStringAccessor(desc, field, resolved_field_name,
                                     class_name, output);
       } else {
         WriteRepeatedScalarAccessor(desc, field, resolved_field_name,
                                     class_name, output);
       }
     } else {
       // non-repeated field.
       if (field->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_STRING) {
         output(
             R"cc(
               $1 $0::$2() const {
                 return ::protos::UpbStrToStringView($3_$4(msg_));
               }
             )cc",
             class_name, CppConstType(field), resolved_field_name,
             MessageName(desc), resolved_upbc_name);
         // Set string.
         output(
             R"cc(
               void $0::set_$2($1 value) {
                 $4_set_$3(msg_, ::protos::UpbStrFromStringView(value, $5));
               }
             )cc",
             class_name, CppConstType(field), resolved_field_name,
             resolved_upbc_name, MessageName(desc), arena_expression);
       } else if (field->cpp_type() ==
                  protobuf::FieldDescriptor::CPPTYPE_MESSAGE) {
         output(
             R"cc(
               $1 $0::$2() const {
                 if (!has_$2()) {
                   return $4::default_instance();
                 }
                 return ::protos::internal::CreateMessage<$4>(
                     (upb_Message*)($3_$5(msg_)), arena_);
               }
             )cc",
             class_name, MessagePtrConstType(field, /* is_const */ true),
             resolved_field_name, MessageName(desc),
             MessageBaseType(field, /* maybe_const */ false),
             resolved_upbc_name);

         output(
             R"cc(
               $1 $0::mutable_$2() {
                 return ::protos::internal::CreateMessageProxy<$4>(
                     (upb_Message*)($3_mutable_$5(msg_, $6)), $6);
               }
             )cc",
             class_name, MessagePtrConstType(field, /* is_const */ false),
             resolved_field_name, MessageName(desc),
             MessageBaseType(field, /* maybe_const */ false), resolved_upbc_name,
             arena_expression);
       }
     }
   }
   output("\n");
   output("}  // namespace internal\n\n");
 }

 void WriteMapAccessorDefinitions(const protobuf::Descriptor* message,
                                  const protobuf::FieldDescriptor* field,
                                  const absl::string_view resolved_field_name,
                                  const absl::string_view class_name,
                                  Output& output) {
   const protobuf::Descriptor* entry = field->message_type();
   const protobuf::FieldDescriptor* key = entry->FindFieldByNumber(1);
   const protobuf::FieldDescriptor* val = entry->FindFieldByNumber(2);
   absl::string_view upbc_name = field->name();
   absl::string_view converted_key_name = "key";
   absl::string_view optional_conversion_code = "";

   if (key->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_STRING) {
     // Insert conversion from absl::string_view to upb_StringView.
     // Creates upb_StringView on stack to prevent allocation.
     converted_key_name = "upb_key";
     optional_conversion_code =
         "upb_StringView upb_key = {key.data(), key.size()};\n";
   }
   if (val->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_MESSAGE) {
     output(
         R"cc(
           bool $0::set_$1($2 key, $3 value) {
             upb_Message* clone = upb_Message_DeepClone(
                 ::protos::internal::PrivateAccess::GetInternalMsg(value), &$9,
                 arena_);
             $6return $4_$8_set(msg_, $7, ($5*)clone, arena_);
           }
         )cc",
         class_name, resolved_field_name, CppConstType(key),
         MessagePtrConstType(val, /* is_const */ true), MessageName(message),
         MessageName(val->message_type()), optional_conversion_code,
         converted_key_name, upbc_name,
         ::upb::generator::MessageInit(val->message_type()->full_name()));
     output(
         R"cc(
           bool $0::set_$1($2 key, $3 value) {
             upb_Message* clone = upb_Message_DeepClone(
                 ::protos::internal::PrivateAccess::GetInternalMsg(value), &$9,
                 arena_);
             $6return $4_$8_set(msg_, $7, ($5*)clone, arena_);
           }
         )cc",
         class_name, resolved_field_name, CppConstType(key),
         MessagePtrConstType(val, /* is_const */ false), MessageName(message),
         MessageName(val->message_type()), optional_conversion_code,
         converted_key_name, upbc_name,
         ::upb::generator::MessageInit(val->message_type()->full_name()));
     output(
         R"cc(
           absl::StatusOr<$3> $0::get_$1($2 key) {
             $5* msg_value;
             $7bool success = $4_$9_get(msg_, $8, &msg_value);
             if (success) {
               return ::protos::internal::CreateMessage<$6>(UPB_UPCAST(msg_value), arena_);
             }
             return absl::NotFoundError("");
           }
         )cc",
         class_name, resolved_field_name, CppConstType(key),
         MessagePtrConstType(val, /* is_const */ true), MessageName(message),
         MessageName(val->message_type()),
         QualifiedClassName(val->message_type()), optional_conversion_code,
         converted_key_name, upbc_name);
     output(
         R"cc(
           void $0::delete_$1($2 key) { $6$4_$8_delete(msg_, $7); }
         )cc",
         class_name, resolved_field_name, CppConstType(key),
         MessagePtrConstType(val, /* is_const */ false), MessageName(message),
         MessageName(val->message_type()), optional_conversion_code,
         converted_key_name, upbc_name);
   } else if (val->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_STRING) {
     output(
         R"cc(
           bool $0::set_$1($2 key, $3 value) {
             $5return $4_$7_set(msg_, $6,
                                ::protos::UpbStrFromStringView(value, arena_),
                                arena_);
           }
         )cc",
         class_name, resolved_field_name, CppConstType(key), CppConstType(val),
         MessageName(message), optional_conversion_code, converted_key_name,
         upbc_name);
     output(
         R"cc(
           absl::StatusOr<$3> $0::get_$1($2 key) {
             upb_StringView value;
             $5bool success = $4_$7_get(msg_, $6, &value);
             if (success) {
               return absl::string_view(value.data, value.size);
             }
             return absl::NotFoundError("");
           }
         )cc",
         class_name, resolved_field_name, CppConstType(key), CppConstType(val),
         MessageName(message), optional_conversion_code, converted_key_name,
         upbc_name);
     output(
         R"cc(
           void $0::delete_$1($2 key) { $5$4_$7_delete(msg_, $6); }
         )cc",
         class_name, resolved_field_name, CppConstType(key), CppConstType(val),
         MessageName(message), optional_conversion_code, converted_key_name,
         upbc_name);
   } else {
     output(
         R"cc(
           bool $0::set_$1($2 key, $3 value) {
             $5return $4_$7_set(msg_, $6, value, arena_);
           }
         )cc",
         class_name, resolved_field_name, CppConstType(key), CppConstType(val),
         MessageName(message), optional_conversion_code, converted_key_name,
         upbc_name);
     output(
         R"cc(
           absl::StatusOr<$3> $0::get_$1($2 key) {
             $3 value;
             $5bool success = $4_$7_get(msg_, $6, &value);
             if (success) {
               return value;
             }
             return absl::NotFoundError("");
           }
         )cc",
         class_name, resolved_field_name, CppConstType(key), CppConstType(val),
         MessageName(message), optional_conversion_code, converted_key_name,
         upbc_name);
     output(
         R"cc(
           void $0::delete_$1($2 key) { $5$4_$7_delete(msg_, $6); }
         )cc",
         class_name, resolved_field_name, CppConstType(key), CppConstType(val),
         MessageName(message), optional_conversion_code, converted_key_name,
         upbc_name);
   }
 }

 void WriteUsingAccessorsInHeader(const protobuf::Descriptor* desc,
                                  MessageClassType handle_type, Output& output) {
   bool read_only = handle_type == MessageClassType::kMessageCProxy;

   // Generate const methods.
   OutputIndenter i(output);
   std::string class_name = ClassName(desc);
   auto field_names = CreateFieldNameMap(desc);

   for (const auto* field : FieldNumberOrder(desc)) {
     std::string resolved_field_name = ResolveFieldName(field, field_names);
     // Generate hazzer (if any).
     if (field->has_presence()) {
       output("using $0Access::has_$1;\n", class_name, resolved_field_name);
       if (!read_only) {
         output("using $0Access::clear_$1;\n", class_name, resolved_field_name);
       }
     }
     if (field->is_map()) {
       output(
           R"cc(
             using $0Access::$1_size;
             using $0Access::get_$1;
           )cc",
           class_name, resolved_field_name);
       if (!read_only) {
         output(
             R"cc(
               using $0Access::clear_$1;
               using $0Access::delete_$1;
               using $0Access::set_$1;
             )cc",
             class_name, resolved_field_name);
       }
     } else if (desc->options().map_entry()) {
       // TODO Implement map entry
     } else if (field->is_repeated()) {
       WriteRepeatedFieldUsingAccessors(field, class_name, resolved_field_name,
                                        output, read_only);
     } else {
       if (field->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_MESSAGE) {
         output("using $0Access::$1;\n", ClassName(desc), resolved_field_name);
         if (!read_only) {
           output("using $0Access::mutable_$1;\n", class_name,
                  resolved_field_name);
         }
       } else {
         output("using $0Access::$1;\n", class_name, resolved_field_name);
         if (!read_only) {
           output("using $0Access::set_$1;\n", class_name, resolved_field_name);
         }
       }
     }
   }
   for (int i = 0; i < desc->real_oneof_decl_count(); ++i) {
     const protobuf::OneofDescriptor* oneof = desc->oneof_decl(i);
     output("using $0Access::$1_case;\n", class_name, oneof->name());
     output("using $0Access::$1Case;\n", class_name,
            ToCamelCase(oneof->name(), /*lower_first=*/false));
     for (int j = 0; j < oneof->field_count(); ++j) {
       const protobuf::FieldDescriptor* field = oneof->field(j);
       output("using $0Access::k$1;\n", class_name,
              ToCamelCase(field->name(), /*lower_first=*/false),
              field->number());
     }
     output("using $0Access::$1_NOT_SET;\n", class_name,
            absl::AsciiStrToUpper(oneof->name()));
   }
 }

 void WriteOneofAccessorsInHeader(const protobuf::Descriptor* desc,
                                  Output& output) {
   // Generate const methods.
   OutputIndenter i(output);
   std::string class_name = ClassName(desc);
   auto field_names = CreateFieldNameMap(desc);
   for (int i = 0; i < desc->real_oneof_decl_count(); ++i) {
     const protobuf::OneofDescriptor* oneof = desc->oneof_decl(i);
     output("enum $0Case {\n",
            ToCamelCase(oneof->name(), /*lower_first=*/false));
     for (int j = 0; j < oneof->field_count(); ++j) {
       const protobuf::FieldDescriptor* field = oneof->field(j);
       output("  k$0 = $1,\n", ToCamelCase(field->name(), /*lower_first=*/false),
              field->number());
     }
     output("  $0_NOT_SET = 0,\n", absl::AsciiStrToUpper(oneof->name()));
     output("};\n\n");
     output("$0Case $1_case() const {\n",
            ToCamelCase(oneof->name(), /*lower_first=*/false), oneof->name());
     for (int j = 0; j < oneof->field_count(); ++j) {
       const protobuf::FieldDescriptor* field = oneof->field(j);
       std::string resolved_field_name = ResolveFieldName(field, field_names);
       output("  if (has_$0()) { return k$1; }\n", resolved_field_name,
              ToCamelCase(field->name(), /*lower_first=*/false));
     }
     output("  return $0_NOT_SET;\n", absl::AsciiStrToUpper(oneof->name()));
     output("}\n;");
   }
 }

 std::string ResolveFieldName(const protobuf::FieldDescriptor* field,
                              const NameToFieldDescriptorMap& field_names) {
   // C++ implementation specific reserved names.
   static const auto& kReservedNames =
       *new absl::flat_hash_set<absl::string_view>({
           "msg",
           "msg_",
           "arena",
           "arena_",
       });

   // C++ specific prefixes used by code generator for field access.
   static constexpr absl::string_view kClearMethodPrefix = "clear_";
   static constexpr absl::string_view kSetMethodPrefix = "set_";
   static constexpr absl::string_view kHasMethodPrefix = "has_";
   static constexpr absl::string_view kDeleteMethodPrefix = "delete_";
   static constexpr absl::string_view kAddToRepeatedMethodPrefix = "add_";
   static constexpr absl::string_view kResizeArrayMethodPrefix = "resize_";

   // List of generated accessor prefixes to check against.
   // Example:
   //     optional repeated string phase = 236;
   //     optional bool clear_phase = 237;
   static constexpr absl::string_view kAccessorPrefixes[] = {
       kClearMethodPrefix,       kDeleteMethodPrefix, kAddToRepeatedMethodPrefix,
       kResizeArrayMethodPrefix, kSetMethodPrefix,    kHasMethodPrefix};

   absl::string_view field_name = field->name();
   if (kReservedNames.count(field_name) > 0) {
     if (absl::EndsWith(field_name, "_")) {
       return absl::StrCat(field_name, "_");
     } else {
       return absl::StrCat(field_name, "__");
     }
   }
   for (const auto prefix : kAccessorPrefixes) {
     // If field name starts with a prefix such as clear_ and the proto
     // contains a field name with trailing end, depending on type of field
     // (repeated, map, message) we have a conflict to resolve.
     if (absl::StartsWith(field_name, prefix)) {
       auto match = field_names.find(field_name.substr(prefix.size()));
       if (match != field_names.end()) {
         const auto* candidate = match->second;
         if (candidate->is_repeated() || candidate->is_map() ||
             (candidate->cpp_type() ==
                  protobuf::FieldDescriptor::CPPTYPE_STRING &&
              prefix == kClearMethodPrefix) ||
             prefix == kSetMethodPrefix || prefix == kHasMethodPrefix) {
           return absl::StrCat(field_name, "_");
         }
       }
     }
   }
   return upb::generator::ResolveKeywordConflict(std::string(field_name));
 }

 }  // namespace protos_generator
	// Protocol Buffers - Google's data interchange format
	// Copyright 2023 Google LLC. All rights reserved.
	//
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file or at
	// https://developers.google.com/open-source/licenses/bsd

	#include "protos_generator/gen_accessors.h"

	#include <string>

	#include "absl/container/flat_hash_set.h"
	#include "absl/strings/match.h"
	#include "absl/strings/str_cat.h"
	#include "absl/strings/string_view.h"
	#include "google/protobuf/descriptor.h"
	#include "protos_generator/gen_repeated_fields.h"
	#include "protos_generator/gen_utils.h"
	#include "protos_generator/names.h"
	#include "protos_generator/output.h"
	#include "upb_generator/common.h"
	#include "upb_generator/keywords.h"
	#include "upb_generator/names.h"

	namespace protos_generator {

	namespace protobuf = ::google::protobuf;

	using NameToFieldDescriptorMap =
	absl::flat_hash_map<absl::string_view, const protobuf::FieldDescriptor*>;

	void WriteFieldAccessorHazzer(const protobuf::Descriptor* desc,
	const protobuf::FieldDescriptor* field,
	absl::string_view resolved_field_name,
	absl::string_view resolved_upbc_name,
	Output& output);
	void WriteFieldAccessorClear(const protobuf::Descriptor* desc,
	const protobuf::FieldDescriptor* field,
	absl::string_view resolved_field_name,
	absl::string_view resolved_upbc_name,
	Output& output);
	void WriteMapFieldAccessors(const protobuf::Descriptor* desc,
	const protobuf::FieldDescriptor* field,
	absl::string_view resolved_field_name,
	absl::string_view resolved_upbc_name,
	Output& output);

	void WriteMapAccessorDefinitions(const protobuf::Descriptor* message,
	const protobuf::FieldDescriptor* field,
	absl::string_view resolved_field_name,
	absl::string_view class_name, Output& output);

	// Returns C++ class member name by resolving naming conflicts across
	// proto field names (such as clear_ prefixes) and keyword collisions.
	//
	// The Upb C generator prefixes all accessors with package and class names
	// avoiding collisions. Therefore we need to use raw field names when calling
	// into C accessors but need to fully resolve conflicts for C++ class members.
	std::string ResolveFieldName(const protobuf::FieldDescriptor* field,
	const NameToFieldDescriptorMap& field_names);

	NameToFieldDescriptorMap CreateFieldNameMap(
	const protobuf::Descriptor* message) {
	NameToFieldDescriptorMap field_names;
	for (int i = 0; i < message->field_count(); i++) {
	const protobuf::FieldDescriptor* field = message->field(i);
	field_names.emplace(field->name(), field);
	}
	return field_names;
	}

	void WriteFieldAccessorsInHeader(const protobuf::Descriptor* desc,
	Output& output) {
	// Generate const methods.
	OutputIndenter i(output);

	auto field_names = CreateFieldNameMap(desc);
	auto upbc_field_names = upb::generator::CreateFieldNameMap(desc);

	for (const auto* field : FieldNumberOrder(desc)) {
	std::string resolved_field_name = ResolveFieldName(field, field_names);
	std::string resolved_upbc_name =
	upb::generator::ResolveFieldName(field, upbc_field_names);
	WriteFieldAccessorHazzer(desc, field, resolved_field_name,
	resolved_upbc_name, output);
	WriteFieldAccessorClear(desc, field, resolved_field_name,
	resolved_upbc_name, output);

	if (field->is_map()) {
	WriteMapFieldAccessors(desc, field, resolved_field_name,
	resolved_upbc_name, output);
	} else if (desc->options().map_entry()) {
	// TODO Implement map entry
	} else if (field->is_repeated()) {
	WriteRepeatedFieldsInMessageHeader(desc, field, resolved_field_name,
	resolved_upbc_name, output);
	} else {
	// non-repeated.
	if (field->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_STRING) {
	output(R"cc(
	$0 $1() const;
	void set_$1($0 value);
	)cc",
	CppConstType(field), resolved_field_name);
	} else if (field->cpp_type() ==
	protobuf::FieldDescriptor::CPPTYPE_MESSAGE) {
	output(R"cc(
	$1 $2() const;
	$0 mutable_$2();
	)cc",
	MessagePtrConstType(field, /* const */ false),
	MessagePtrConstType(field, /* const */ true),
	resolved_field_name, resolved_upbc_name);
	} else {
	output(
	R"cc(
	inline $0 $1() const { return $2_$3(msg_); }
	inline void set_$1($0 value) { return $2_set_$3(msg_, value); }
	)cc",
	CppConstType(field), resolved_field_name, MessageName(desc),
	resolved_upbc_name);
	}
	}
	}
	}

	void WriteFieldAccessorHazzer(const protobuf::Descriptor* desc,
	const protobuf::FieldDescriptor* field,
	const absl::string_view resolved_field_name,
	const absl::string_view resolved_upbc_name,
	Output& output) {
	// Generate hazzer (if any).
	if (field->has_presence()) {
	// Has presence.
	output("inline bool has_$0() const { return $1_has_$2(msg_); }\n",
	resolved_field_name, MessageName(desc), resolved_upbc_name);
	}
	}

	void WriteFieldAccessorClear(const protobuf::Descriptor* desc,
	const protobuf::FieldDescriptor* field,
	const absl::string_view resolved_field_name,
	const absl::string_view resolved_upbc_name,
	Output& output) {
	if (field->has_presence()) {
	output("void clear_$0() { $2_clear_$1(msg_); }\n", resolved_field_name,
	resolved_upbc_name, MessageName(desc));
	}
	}

	void WriteMapFieldAccessors(const protobuf::Descriptor* desc,
	const protobuf::FieldDescriptor* field,
	const absl::string_view resolved_field_name,
	const absl::string_view resolved_upbc_name,
	Output& output) {
	const protobuf::Descriptor* entry = field->message_type();
	const protobuf::FieldDescriptor* key = entry->FindFieldByNumber(1);
	const protobuf::FieldDescriptor* val = entry->FindFieldByNumber(2);
	output(
	R"cc(
	inline size_t $0_size() const { return $1_$3_size(msg_); }
	inline void clear_$0() { $1_clear_$3(msg_); }
	void delete_$0($2 key);
	)cc",
	resolved_field_name, MessageName(desc), CppConstType(key),
	resolved_upbc_name);

	if (val->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_MESSAGE) {
	output(
	R"cc(
	bool set_$0($1 key, $3 value);
	bool set_$0($1 key, $4 value);
	absl::StatusOr<$3> get_$0($1 key);
	)cc",
	resolved_field_name, CppConstType(key), CppConstType(val),
	MessagePtrConstType(val, /* is_const */ true),
	MessagePtrConstType(val, /* is_const */ false));
	} else {
	output(
	R"cc(
	bool set_$0($1 key, $2 value);
	absl::StatusOr<$2> get_$0($1 key);
	)cc",
	resolved_field_name, CppConstType(key), CppConstType(val));
	}
	}

	void WriteAccessorsInSource(const protobuf::Descriptor* desc, Output& output) {
	std::string class_name = ClassName(desc);
	absl::StrAppend(&class_name, "Access");
	output("namespace internal {\n");
	const char arena_expression[] = "arena_";
	auto field_names = CreateFieldNameMap(desc);
	auto upbc_field_names = upb::generator::CreateFieldNameMap(desc);

	// Generate const methods.
	OutputIndenter i(output);
	for (const auto* field : FieldNumberOrder(desc)) {
	std::string resolved_field_name = ResolveFieldName(field, field_names);
	std::string resolved_upbc_name =
	upb::generator::ResolveFieldName(field, upbc_field_names);
	if (field->is_map()) {
	WriteMapAccessorDefinitions(desc, field, resolved_field_name, class_name,
	output);
	} else if (desc->options().map_entry()) {
	// TODO Implement map entry
	} else if (field->is_repeated()) {
	if (field->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_MESSAGE) {
	WriteRepeatedMessageAccessor(desc, field, resolved_field_name,
	class_name, output);
	} else if (field->cpp_type() ==
	protobuf::FieldDescriptor::CPPTYPE_STRING) {
	WriteRepeatedStringAccessor(desc, field, resolved_field_name,
	class_name, output);
	} else {
	WriteRepeatedScalarAccessor(desc, field, resolved_field_name,
	class_name, output);
	}
	} else {
	// non-repeated field.
	if (field->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_STRING) {
	output(
	R"cc(
	$1 $0::$2() const {
	return ::protos::UpbStrToStringView($3_$4(msg_));
	}
	)cc",
	class_name, CppConstType(field), resolved_field_name,
	MessageName(desc), resolved_upbc_name);
	// Set string.
	output(
	R"cc(
	void $0::set_$2($1 value) {
	$4_set_$3(msg_, ::protos::UpbStrFromStringView(value, $5));
	}
	)cc",
	class_name, CppConstType(field), resolved_field_name,
	resolved_upbc_name, MessageName(desc), arena_expression);
	} else if (field->cpp_type() ==
	protobuf::FieldDescriptor::CPPTYPE_MESSAGE) {
	output(
	R"cc(
	$1 $0::$2() const {
	if (!has_$2()) {
	return $4::default_instance();
	}
	return ::protos::internal::CreateMessage<$4>(
	(upb_Message*)($3_$5(msg_)), arena_);
	}
	)cc",
	class_name, MessagePtrConstType(field, /* is_const */ true),
	resolved_field_name, MessageName(desc),
	MessageBaseType(field, /* maybe_const */ false),
	resolved_upbc_name);

	output(
	R"cc(
	$1 $0::mutable_$2() {
	return ::protos::internal::CreateMessageProxy<$4>(
	(upb_Message*)($3_mutable_$5(msg_, $6)), $6);
	}
	)cc",
	class_name, MessagePtrConstType(field, /* is_const */ false),
	resolved_field_name, MessageName(desc),
	MessageBaseType(field, /* maybe_const */ false), resolved_upbc_name,
	arena_expression);
	}
	}
	}
	output("\n");
	output("} // namespace internal\n\n");
	}

	void WriteMapAccessorDefinitions(const protobuf::Descriptor* message,
	const protobuf::FieldDescriptor* field,
	const absl::string_view resolved_field_name,
	const absl::string_view class_name,
	Output& output) {
	const protobuf::Descriptor* entry = field->message_type();
	const protobuf::FieldDescriptor* key = entry->FindFieldByNumber(1);
	const protobuf::FieldDescriptor* val = entry->FindFieldByNumber(2);
	absl::string_view upbc_name = field->name();
	absl::string_view converted_key_name = "key";
	absl::string_view optional_conversion_code = "";

	if (key->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_STRING) {
	// Insert conversion from absl::string_view to upb_StringView.
	// Creates upb_StringView on stack to prevent allocation.
	converted_key_name = "upb_key";
	optional_conversion_code =
	"upb_StringView upb_key = {key.data(), key.size()};\n";
	}
	if (val->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_MESSAGE) {
	output(
	R"cc(
	bool $0::set_$1($2 key, $3 value) {
	upb_Message* clone = upb_Message_DeepClone(
	::protos::internal::PrivateAccess::GetInternalMsg(value), &$9,
	arena_);
	$6return $4_$8_set(msg_, $7, ($5*)clone, arena_);
	}
	)cc",
	class_name, resolved_field_name, CppConstType(key),
	MessagePtrConstType(val, /* is_const */ true), MessageName(message),
	MessageName(val->message_type()), optional_conversion_code,
	converted_key_name, upbc_name,
	::upb::generator::MessageInit(val->message_type()->full_name()));
	output(
	R"cc(
	bool $0::set_$1($2 key, $3 value) {
	upb_Message* clone = upb_Message_DeepClone(
	::protos::internal::PrivateAccess::GetInternalMsg(value), &$9,
	arena_);
	$6return $4_$8_set(msg_, $7, ($5*)clone, arena_);
	}
	)cc",
	class_name, resolved_field_name, CppConstType(key),
	MessagePtrConstType(val, /* is_const */ false), MessageName(message),
	MessageName(val->message_type()), optional_conversion_code,
	converted_key_name, upbc_name,
	::upb::generator::MessageInit(val->message_type()->full_name()));
	output(
	R"cc(
	absl::StatusOr<$3> $0::get_$1($2 key) {
	$5* msg_value;
	$7bool success = $4_$9_get(msg_, $8, &msg_value);
	if (success) {
	return ::protos::internal::CreateMessage<$6>(UPB_UPCAST(msg_value), arena_);
	}
	return absl::NotFoundError("");
	}
	)cc",
	class_name, resolved_field_name, CppConstType(key),
	MessagePtrConstType(val, /* is_const */ true), MessageName(message),
	MessageName(val->message_type()),
	QualifiedClassName(val->message_type()), optional_conversion_code,
	converted_key_name, upbc_name);
	output(
	R"cc(
	void $0::delete_$1($2 key) { $6$4_$8_delete(msg_, $7); }
	)cc",
	class_name, resolved_field_name, CppConstType(key),
	MessagePtrConstType(val, /* is_const */ false), MessageName(message),
	MessageName(val->message_type()), optional_conversion_code,
	converted_key_name, upbc_name);
	} else if (val->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_STRING) {
	output(
	R"cc(
	bool $0::set_$1($2 key, $3 value) {
	$5return $4_$7_set(msg_, $6,
	::protos::UpbStrFromStringView(value, arena_),
	arena_);
	}
	)cc",
	class_name, resolved_field_name, CppConstType(key), CppConstType(val),
	MessageName(message), optional_conversion_code, converted_key_name,
	upbc_name);
	output(
	R"cc(
	absl::StatusOr<$3> $0::get_$1($2 key) {
	upb_StringView value;
	$5bool success = $4_$7_get(msg_, $6, &value);
	if (success) {
	return absl::string_view(value.data, value.size);
	}
	return absl::NotFoundError("");
	}
	)cc",
	class_name, resolved_field_name, CppConstType(key), CppConstType(val),
	MessageName(message), optional_conversion_code, converted_key_name,
	upbc_name);
	output(
	R"cc(
	void $0::delete_$1($2 key) { $5$4_$7_delete(msg_, $6); }
	)cc",
	class_name, resolved_field_name, CppConstType(key), CppConstType(val),
	MessageName(message), optional_conversion_code, converted_key_name,
	upbc_name);
	} else {
	output(
	R"cc(
	bool $0::set_$1($2 key, $3 value) {
	$5return $4_$7_set(msg_, $6, value, arena_);
	}
	)cc",
	class_name, resolved_field_name, CppConstType(key), CppConstType(val),
	MessageName(message), optional_conversion_code, converted_key_name,
	upbc_name);
	output(
	R"cc(
	absl::StatusOr<$3> $0::get_$1($2 key) {
	$3 value;
	$5bool success = $4_$7_get(msg_, $6, &value);
	if (success) {
	return value;
	}
	return absl::NotFoundError("");
	}
	)cc",
	class_name, resolved_field_name, CppConstType(key), CppConstType(val),
	MessageName(message), optional_conversion_code, converted_key_name,
	upbc_name);
	output(
	R"cc(
	void $0::delete_$1($2 key) { $5$4_$7_delete(msg_, $6); }
	)cc",
	class_name, resolved_field_name, CppConstType(key), CppConstType(val),
	MessageName(message), optional_conversion_code, converted_key_name,
	upbc_name);
	}
	}

	void WriteUsingAccessorsInHeader(const protobuf::Descriptor* desc,
	MessageClassType handle_type, Output& output) {
	bool read_only = handle_type == MessageClassType::kMessageCProxy;

	// Generate const methods.
	OutputIndenter i(output);
	std::string class_name = ClassName(desc);
	auto field_names = CreateFieldNameMap(desc);

	for (const auto* field : FieldNumberOrder(desc)) {
	std::string resolved_field_name = ResolveFieldName(field, field_names);
	// Generate hazzer (if any).
	if (field->has_presence()) {
	output("using $0Access::has_$1;\n", class_name, resolved_field_name);
	if (!read_only) {
	output("using $0Access::clear_$1;\n", class_name, resolved_field_name);
	}
	}
	if (field->is_map()) {
	output(
	R"cc(
	using $0Access::$1_size;
	using $0Access::get_$1;
	)cc",
	class_name, resolved_field_name);
	if (!read_only) {
	output(
	R"cc(
	using $0Access::clear_$1;
	using $0Access::delete_$1;
	using $0Access::set_$1;
	)cc",
	class_name, resolved_field_name);
	}
	} else if (desc->options().map_entry()) {
	// TODO Implement map entry
	} else if (field->is_repeated()) {
	WriteRepeatedFieldUsingAccessors(field, class_name, resolved_field_name,
	output, read_only);
	} else {
	if (field->cpp_type() == protobuf::FieldDescriptor::CPPTYPE_MESSAGE) {
	output("using $0Access::$1;\n", ClassName(desc), resolved_field_name);
	if (!read_only) {
	output("using $0Access::mutable_$1;\n", class_name,
	resolved_field_name);
	}
	} else {
	output("using $0Access::$1;\n", class_name, resolved_field_name);
	if (!read_only) {
	output("using $0Access::set_$1;\n", class_name, resolved_field_name);
	}
	}
	}
	}
	for (int i = 0; i < desc->real_oneof_decl_count(); ++i) {
	const protobuf::OneofDescriptor* oneof = desc->oneof_decl(i);
	output("using $0Access::$1_case;\n", class_name, oneof->name());
	output("using $0Access::$1Case;\n", class_name,
	ToCamelCase(oneof->name(), /lower_first=/false));
	for (int j = 0; j < oneof->field_count(); ++j) {
	const protobuf::FieldDescriptor* field = oneof->field(j);
	output("using $0Access::k$1;\n", class_name,
	ToCamelCase(field->name(), /lower_first=/false),
	field->number());
	}
	output("using $0Access::$1_NOT_SET;\n", class_name,
	absl::AsciiStrToUpper(oneof->name()));
	}
	}

	void WriteOneofAccessorsInHeader(const protobuf::Descriptor* desc,
	Output& output) {
	// Generate const methods.
	OutputIndenter i(output);
	std::string class_name = ClassName(desc);
	auto field_names = CreateFieldNameMap(desc);
	for (int i = 0; i < desc->real_oneof_decl_count(); ++i) {
	const protobuf::OneofDescriptor* oneof = desc->oneof_decl(i);
	output("enum $0Case {\n",
	ToCamelCase(oneof->name(), /lower_first=/false));
	for (int j = 0; j < oneof->field_count(); ++j) {
	const protobuf::FieldDescriptor* field = oneof->field(j);
	output(" k$0 = $1,\n", ToCamelCase(field->name(), /lower_first=/false),
	field->number());
	}
	output(" $0_NOT_SET = 0,\n", absl::AsciiStrToUpper(oneof->name()));
	output("};\n\n");
	output("$0Case $1_case() const {\n",
	ToCamelCase(oneof->name(), /lower_first=/false), oneof->name());
	for (int j = 0; j < oneof->field_count(); ++j) {
	const protobuf::FieldDescriptor* field = oneof->field(j);
	std::string resolved_field_name = ResolveFieldName(field, field_names);
	output(" if (has_$0()) { return k$1; }\n", resolved_field_name,
	ToCamelCase(field->name(), /lower_first=/false));
	}
	output(" return $0_NOT_SET;\n", absl::AsciiStrToUpper(oneof->name()));
	output("}\n;");
	}
	}

	std::string ResolveFieldName(const protobuf::FieldDescriptor* field,
	const NameToFieldDescriptorMap& field_names) {
	// C++ implementation specific reserved names.
	static const auto& kReservedNames =
	*new absl::flat_hash_set<absl::string_view>({
	"msg",
	"msg_",
	"arena",
	"arena_",
	});

	// C++ specific prefixes used by code generator for field access.
	static constexpr absl::string_view kClearMethodPrefix = "clear_";
	static constexpr absl::string_view kSetMethodPrefix = "set_";
	static constexpr absl::string_view kHasMethodPrefix = "has_";
	static constexpr absl::string_view kDeleteMethodPrefix = "delete_";
	static constexpr absl::string_view kAddToRepeatedMethodPrefix = "add_";
	static constexpr absl::string_view kResizeArrayMethodPrefix = "resize_";

	// List of generated accessor prefixes to check against.
	// Example:
	// optional repeated string phase = 236;
	// optional bool clear_phase = 237;
	static constexpr absl::string_view kAccessorPrefixes[] = {
	kClearMethodPrefix, kDeleteMethodPrefix, kAddToRepeatedMethodPrefix,
	kResizeArrayMethodPrefix, kSetMethodPrefix, kHasMethodPrefix};

	absl::string_view field_name = field->name();
	if (kReservedNames.count(field_name) > 0) {
	if (absl::EndsWith(field_name, "_")) {
	return absl::StrCat(field_name, "_");
	} else {
	return absl::StrCat(field_name, "__");
	}
	}
	for (const auto prefix : kAccessorPrefixes) {
	// If field name starts with a prefix such as clear_ and the proto
	// contains a field name with trailing end, depending on type of field
	// (repeated, map, message) we have a conflict to resolve.
	if (absl::StartsWith(field_name, prefix)) {
	auto match = field_names.find(field_name.substr(prefix.size()));
	if (match != field_names.end()) {
	const auto* candidate = match->second;
	if (candidate->is_repeated() \|\| candidate->is_map() \|\|
	(candidate->cpp_type() ==
	protobuf::FieldDescriptor::CPPTYPE_STRING &&
	prefix == kClearMethodPrefix) \|\|
	prefix == kSetMethodPrefix \|\| prefix == kHasMethodPrefix) {
	return absl::StrCat(field_name, "_");
	}
	}
	}
	}
	return upb::generator::ResolveKeywordConflict(std::string(field_name));
	}

	} // namespace protos_generator