hpb_generator/gen_messages.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 "google/protobuf/compiler/hpb/gen_messages.h"

 #include <cstddef>
 #include <string>
 #include <vector>

 #include "google/protobuf/descriptor.pb.h"
 #include "absl/strings/ascii.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/compiler/hpb/gen_accessors.h"
 #include "google/protobuf/compiler/hpb/gen_enums.h"
 #include "google/protobuf/compiler/hpb/gen_extensions.h"
 #include "google/protobuf/compiler/hpb/gen_utils.h"
 #include "google/protobuf/compiler/hpb/names.h"
 #include "google/protobuf/compiler/hpb/output.h"
 #include "upb_generator/common.h"
 #include "upb_generator/file_layout.h"

 namespace google::protobuf::hpb_generator {

 namespace protobuf = ::proto2;

 void WriteModelAccessDeclaration(const protobuf::Descriptor* descriptor,
                                  Output& output);
 void WriteModelPublicDeclaration(
     const protobuf::Descriptor* descriptor,
     const std::vector<const protobuf::FieldDescriptor*>& file_exts,
     const std::vector<const protobuf::EnumDescriptor*>& file_enums,
     Output& output);
 void WriteExtensionIdentifiersInClassHeader(
     const protobuf::Descriptor* message,
     const std::vector<const protobuf::FieldDescriptor*>& file_exts,
     Output& output);
 void WriteModelProxyDeclaration(const protobuf::Descriptor* descriptor,
                                 Output& output);
 void WriteModelCProxyDeclaration(const protobuf::Descriptor* descriptor,
                                  Output& output);
 void WriteInternalForwardDeclarationsInHeader(
     const protobuf::Descriptor* message, Output& output);
 void WriteDefaultInstanceHeader(const protobuf::Descriptor* message,
                                 Output& output);
 void WriteExtensionIdentifiersImplementation(
     const protobuf::Descriptor* message,
     const std::vector<const protobuf::FieldDescriptor*>& file_exts,
     Output& output);
 void WriteUsingEnumsInHeader(
     const protobuf::Descriptor* message,
     const std::vector<const protobuf::EnumDescriptor*>& file_enums,
     Output& output);

 // Writes message class declarations into .upb.proto.h.
 //
 // For each proto Foo, FooAccess and FooProxy/FooCProxy are generated
 // that are exposed to users as Foo , Ptr<Foo> and Ptr<const Foo>.
 void WriteMessageClassDeclarations(
     const protobuf::Descriptor* descriptor,
     const std::vector<const protobuf::FieldDescriptor*>& file_exts,
     const std::vector<const protobuf::EnumDescriptor*>& file_enums,
     Output& output) {
   if (IsMapEntryMessage(descriptor)) {
     // Skip map entry generation. Low level accessors for maps are
     // generated that don't require a separate map type.
     return;
   }

   // Forward declaration of Proto Class for GCC handling of free friend method.
   output("class $0;\n", ClassName(descriptor));
   output("namespace internal {\n\n");
   WriteModelAccessDeclaration(descriptor, output);
   output("\n");
   WriteInternalForwardDeclarationsInHeader(descriptor, output);
   output("\n");
   output("}  // namespace internal\n\n");
   WriteModelPublicDeclaration(descriptor, file_exts, file_enums, output);
   output("namespace internal {\n");
   WriteModelCProxyDeclaration(descriptor, output);
   WriteModelProxyDeclaration(descriptor, output);
   output("}  // namespace internal\n\n");
 }

 void WriteModelAccessDeclaration(const protobuf::Descriptor* descriptor,
                                  Output& output) {
   output(
       R"cc(
         class $0Access {
          public:
           $0Access() {}
           $0Access($1* msg, upb_Arena* arena) : msg_(msg), arena_(arena) {
             assert(arena != nullptr);
           }  // NOLINT
           $0Access(const $1* msg, upb_Arena* arena)
               : msg_(const_cast<$1*>(msg)), arena_(arena) {
             assert(arena != nullptr);
           }  // NOLINT
           void* GetInternalArena() const { return arena_; }
       )cc",
       ClassName(descriptor), MessageName(descriptor));
   WriteFieldAccessorsInHeader(descriptor, output);
   WriteOneofAccessorsInHeader(descriptor, output);
   output.Indent();
   output(
       R"cc(
         private:
         friend class $2;
         friend class $0Proxy;
         friend class $0CProxy;
         friend struct ::protos::internal::PrivateAccess;
         $1* msg_;
         upb_Arena* arena_;
       )cc",
       ClassName(descriptor), MessageName(descriptor),
       QualifiedClassName(descriptor));
   output.Outdent();
   output("};\n");
 }

 std::string UnderscoresToCamelCase(absl::string_view input,
                                    bool cap_next_letter) {
   std::string result;

   for (size_t i = 0; i < input.size(); i++) {
     if (absl::ascii_islower(input[i])) {
       if (cap_next_letter) {
         result += absl::ascii_toupper(input[i]);
       } else {
         result += input[i];
       }
       cap_next_letter = false;
     } else if (absl::ascii_isupper(input[i])) {
       // Capital letters are left as-is.
       result += input[i];
       cap_next_letter = false;
     } else if (absl::ascii_isdigit(input[i])) {
       result += input[i];
       cap_next_letter = true;
     } else {
       cap_next_letter = true;
     }
   }
   return result;
 }

 std::string FieldConstantName(const protobuf::FieldDescriptor* field) {
   std::string field_name = UnderscoresToCamelCase(field->name(), true);
   std::string result = absl::StrCat("k", field_name, "FieldNumber");

   if (!field->is_extension() &&
       field->containing_type()->FindFieldByCamelcaseName(
           field->camelcase_name()) != field) {
     // This field's camelcase name is not unique, add field number to make it
     // unique.
     absl::StrAppend(&result, "_", field->number());
   }
   return result;
 }

 void WriteConstFieldNumbers(Output& output,
                             const protobuf::Descriptor* descriptor) {
   for (auto field : FieldRange(descriptor)) {
     output("static constexpr ::uint32_t $0 = $1;\n", FieldConstantName(field),
            field->number());
   }
   output("\n\n");
 }

 void WriteModelPublicDeclaration(
     const protobuf::Descriptor* descriptor,
     const std::vector<const protobuf::FieldDescriptor*>& file_exts,
     const std::vector<const protobuf::EnumDescriptor*>& file_enums,
     Output& output) {
   output(
       R"cc(
         class $0 final : private internal::$0Access {
          public:
           using Access = internal::$0Access;
           using Proxy = internal::$0Proxy;
           using CProxy = internal::$0CProxy;

           $0();

           $0(const $0& from);
           $0& operator=(const $3& from);
           $0(const CProxy& from);
           $0(const Proxy& from);
           $0& operator=(const CProxy& from);

           $0($0&& m)
               : Access(std::exchange(m.msg_, nullptr),
                        std::exchange(m.arena_, nullptr)),
                 owned_arena_(std::move(m.owned_arena_)) {}

           $0& operator=($0&& m) {
             msg_ = std::exchange(m.msg_, nullptr);
             arena_ = std::exchange(m.arena_, nullptr);
             owned_arena_ = std::move(m.owned_arena_);
             return *this;
           }
       )cc",
       ClassName(descriptor),
       ::upb::generator::MessageInit(descriptor->full_name()),
       MessageName(descriptor), QualifiedClassName(descriptor));

   WriteUsingAccessorsInHeader(descriptor, MessageClassType::kMessage, output);
   WriteUsingEnumsInHeader(descriptor, file_enums, output);
   WriteDefaultInstanceHeader(descriptor, output);
   WriteExtensionIdentifiersInClassHeader(descriptor, file_exts, output);
   if (descriptor->extension_range_count()) {
     // for typetrait checking
     output("using ExtendableType = $0;\n", ClassName(descriptor));
   }
   // Note: free function friends that are templates such as ::protos::Parse
   // require explicit <$2> type parameter in declaration to be able to compile
   // with gcc otherwise the compiler will fail with
   // "has not been declared within namespace" error. Even though there is a
   // namespace qualifier, cross namespace matching fails.
   output.Indent();
   output(
       R"cc(
         static const upb_MiniTable* minitable();
         using $0Access::GetInternalArena;
       )cc",
       ClassName(descriptor));
   output("\n");
   WriteConstFieldNumbers(output, descriptor);
   output(
       R"cc(
         private:
         const upb_Message* msg() const { return UPB_UPCAST(msg_); }
         upb_Message* msg() { return UPB_UPCAST(msg_); }

         $0(upb_Message* msg, upb_Arena* arena) : $0Access() {
           msg_ = ($1*)msg;
           arena_ = owned_arena_.ptr();
           upb_Arena_Fuse(arena_, arena);
         }
         ::protos::Arena owned_arena_;
         friend struct ::protos::internal::PrivateAccess;
         friend Proxy;
         friend CProxy;
         friend absl::StatusOr<$2>(::protos::Parse<$2>(absl::string_view bytes,
                                                       int options));
         friend absl::StatusOr<$2>(::protos::Parse<$2>(
             absl::string_view bytes,
             const ::protos::ExtensionRegistry& extension_registry,
             int options));
         friend upb_Arena* ::protos::internal::GetArena<$0>($0* message);
         friend upb_Arena* ::protos::internal::GetArena<$0>(::protos::Ptr<$0> message);
         friend $0(::protos::internal::MoveMessage<$0>(upb_Message* msg,
                                                       upb_Arena* arena));
       )cc",
       ClassName(descriptor), MessageName(descriptor),
       QualifiedClassName(descriptor));
   output.Outdent();
   output("};\n\n");
 }

 void WriteModelProxyDeclaration(const protobuf::Descriptor* descriptor,
                                 Output& output) {
   // Foo::Proxy.
   output(
       R"cc(
         class $0Proxy final : private internal::$0Access {
          public:
           $0Proxy() = delete;
           $0Proxy(const $0Proxy& m) : internal::$0Access() {
             msg_ = m.msg_;
             arena_ = m.arena_;
           }
           $0Proxy($0* m) : internal::$0Access() {
             msg_ = m->msg_;
             arena_ = m->arena_;
           }
           $0Proxy operator=(const $0Proxy& m) {
             msg_ = m.msg_;
             arena_ = m.arena_;
             return *this;
           }
           using $0Access::GetInternalArena;
       )cc",
       ClassName(descriptor));

   WriteUsingAccessorsInHeader(descriptor, MessageClassType::kMessageProxy,
                               output);
   output("\n");
   output.Indent(1);
   output(
       R"cc(
         private:
         upb_Message* msg() const { return UPB_UPCAST(msg_); }

         $0Proxy(upb_Message* msg, upb_Arena* arena)
             : internal::$0Access(($1*)msg, arena) {}
         friend $0::Proxy(::protos::CreateMessage<$0>(::protos::Arena& arena));
         friend $0::Proxy(::protos::internal::CreateMessageProxy<$0>(
             upb_Message*, upb_Arena*));
         friend struct ::protos::internal::PrivateAccess;
         friend class RepeatedFieldProxy;
         friend class $0CProxy;
         friend class $0Access;
         friend class ::protos::Ptr<$0>;
         friend class ::protos::Ptr<const $0>;
         static const upb_MiniTable* minitable() { return $0::minitable(); }
         friend const upb_MiniTable* ::protos::internal::GetMiniTable<$0Proxy>(
             const $0Proxy* message);
         friend const upb_MiniTable* ::protos::internal::GetMiniTable<$0Proxy>(
             ::protos::Ptr<$0Proxy> message);
         friend upb_Arena* ::protos::internal::GetArena<$2>($2* message);
         friend upb_Arena* ::protos::internal::GetArena<$2>(::protos::Ptr<$2> message);
         static void Rebind($0Proxy& lhs, const $0Proxy& rhs) {
           lhs.msg_ = rhs.msg_;
           lhs.arena_ = rhs.arena_;
         }
       )cc",
       ClassName(descriptor), MessageName(descriptor),
       QualifiedClassName(descriptor));
   output.Outdent(1);
   output("};\n\n");
 }

 void WriteModelCProxyDeclaration(const protobuf::Descriptor* descriptor,
                                  Output& output) {
   // Foo::CProxy.
   output(
       R"cc(
         class $0CProxy final : private internal::$0Access {
          public:
           $0CProxy() = delete;
           $0CProxy(const $0* m)
               : internal::$0Access(m->msg_, ::protos::internal::GetArena(m)) {}
           $0CProxy($0Proxy m);
           using $0Access::GetInternalArena;
       )cc",
       ClassName(descriptor), MessageName(descriptor));

   WriteUsingAccessorsInHeader(descriptor, MessageClassType::kMessageCProxy,
                               output);

   output.Indent(1);
   output(
       R"cc(
         private:
         using AsNonConst = $0Proxy;
         const upb_Message* msg() const { return UPB_UPCAST(msg_); }

         $0CProxy(const upb_Message* msg, upb_Arena* arena)
             : internal::$0Access(($1*)msg, arena){};
         friend struct ::protos::internal::PrivateAccess;
         friend class RepeatedFieldProxy;
         friend class ::protos::Ptr<$0>;
         friend class ::protos::Ptr<const $0>;
         static const upb_MiniTable* minitable() { return $0::minitable(); }
         friend const upb_MiniTable* ::protos::internal::GetMiniTable<$0CProxy>(
             const $0CProxy* message);
         friend const upb_MiniTable* ::protos::internal::GetMiniTable<$0CProxy>(
             ::protos::Ptr<$0CProxy> message);

         static void Rebind($0CProxy& lhs, const $0CProxy& rhs) {
           lhs.msg_ = rhs.msg_;
           lhs.arena_ = rhs.arena_;
         }
       )cc",
       ClassName(descriptor), MessageName(descriptor));
   output.Outdent(1);
   output("};\n\n");
 }

 void WriteDefaultInstanceHeader(const protobuf::Descriptor* message,
                                 Output& output) {
   output("  static ::protos::Ptr<const $0> default_instance();\n",
          ClassName(message));
 }

 void WriteMessageImplementation(
     const protobuf::Descriptor* descriptor,
     const std::vector<const protobuf::FieldDescriptor*>& file_exts,
     Output& output) {
   bool message_is_map_entry = descriptor->options().map_entry();
   if (!message_is_map_entry) {
     // Constructor.
     output(
         R"cc(
           $0::$0() : $0Access() {
             arena_ = owned_arena_.ptr();
             msg_ = $1_new(arena_);
           }
           $0::$0(const $0& from) : $0Access() {
             arena_ = owned_arena_.ptr();
             msg_ = ($1*)::protos::internal::DeepClone(UPB_UPCAST(from.msg_), &$2, arena_);
           }
           $0::$0(const CProxy& from) : $0Access() {
             arena_ = owned_arena_.ptr();
             msg_ = ($1*)::protos::internal::DeepClone(
                 ::protos::internal::GetInternalMsg(&from), &$2, arena_);
           }
           $0::$0(const Proxy& from) : $0(static_cast<const CProxy&>(from)) {}
           internal::$0CProxy::$0CProxy($0Proxy m) : $0Access() {
             arena_ = m.arena_;
             msg_ = ($1*)::protos::internal::GetInternalMsg(&m);
           }
           $0& $0::operator=(const $3& from) {
             arena_ = owned_arena_.ptr();
             msg_ = ($1*)::protos::internal::DeepClone(UPB_UPCAST(from.msg_), &$2, arena_);
             return *this;
           }
           $0& $0::operator=(const CProxy& from) {
             arena_ = owned_arena_.ptr();
             msg_ = ($1*)::protos::internal::DeepClone(
                 ::protos::internal::GetInternalMsg(&from), &$2, arena_);
             return *this;
           }
         )cc",
         ClassName(descriptor), MessageName(descriptor),
         ::upb::generator::MessageInit(descriptor->full_name()),
         QualifiedClassName(descriptor));
     output("\n");
     // Minitable
     output(
         R"cc(
           const upb_MiniTable* $0::minitable() { return &$1; }
         )cc",
         ClassName(descriptor),
         ::upb::generator::MessageInit(descriptor->full_name()));
     output("\n");
   }

   WriteAccessorsInSource(descriptor, output);

   if (!message_is_map_entry) {
     output(
         R"cc(
           struct $0DefaultTypeInternal {
             $1* msg;
             upb_Arena* arena;
           };
           static $0DefaultTypeInternal _$0DefaultTypeBuilder() {
             upb_Arena* arena = upb_Arena_New();
             return $0DefaultTypeInternal{$1_new(arena), arena};
           }
           $0DefaultTypeInternal _$0_default_instance_ = _$0DefaultTypeBuilder();
         )cc",
         ClassName(descriptor), MessageName(descriptor));

     output(
         R"cc(
           ::protos::Ptr<const $0> $0::default_instance() {
             return ::protos::internal::CreateMessage<$0>(
                 (upb_Message *)_$0_default_instance_.msg,
                 _$0_default_instance_.arena);
           }
         )cc",
         ClassName(descriptor));

     WriteExtensionIdentifiersImplementation(descriptor, file_exts, output);
   }
 }

 void WriteInternalForwardDeclarationsInHeader(
     const protobuf::Descriptor* message, Output& output) {
   // Write declaration for internal re-usable default_instance without
   // leaking implementation.
   output(
       R"cc(
         struct $0DefaultTypeInternal;
         extern $0DefaultTypeInternal _$0_default_instance_;
       )cc",
       ClassName(message));
 }

 void WriteExtensionIdentifiersInClassHeader(
     const protobuf::Descriptor* message,
     const std::vector<const protobuf::FieldDescriptor*>& file_exts,
     Output& output) {
   for (auto* ext : file_exts) {
     if (ext->extension_scope() &&
         ext->extension_scope()->full_name() == message->full_name()) {
       WriteExtensionIdentifierHeader(ext, output);
     }
   }
 }

 void WriteExtensionIdentifiersImplementation(
     const protobuf::Descriptor* message,
     const std::vector<const protobuf::FieldDescriptor*>& file_exts,
     Output& output) {
   for (auto* ext : file_exts) {
     if (ext->extension_scope() &&
         ext->extension_scope()->full_name() == message->full_name()) {
       WriteExtensionIdentifier(ext, output);
     }
   }
 }

 void WriteUsingEnumsInHeader(
     const protobuf::Descriptor* message,
     const std::vector<const protobuf::EnumDescriptor*>& file_enums,
     Output& output) {
   for (auto* enum_descriptor : file_enums) {
     std::string enum_type_name = EnumTypeName(enum_descriptor);
     std::string enum_resolved_type_name =
         enum_descriptor->file()->package().empty() &&
                 enum_descriptor->containing_type() == nullptr
             ? absl::StrCat(kNoPackageNamePrefix,
                            ToCIdent(enum_descriptor->name()))
             : enum_type_name;
     if (enum_descriptor->containing_type() == nullptr ||
         enum_descriptor->containing_type()->full_name() !=
             message->full_name()) {
       continue;
     }
     output("using $0", enum_descriptor->name());
     if (enum_descriptor->options().deprecated()) {
       output(" ABSL_DEPRECATED(\"Proto enum $0\")", enum_descriptor->name());
     }
     output(" = $0;", enum_resolved_type_name);
     output("\n");
     int value_count = enum_descriptor->value_count();
     for (int i = 0; i < value_count; i++) {
       output("static constexpr $0 $1", enum_descriptor->name(),
              enum_descriptor->value(i)->name());
       if (enum_descriptor->options().deprecated() ||
           enum_descriptor->value(i)->options().deprecated()) {
         output(" ABSL_DEPRECATED(\"Proto enum value $0\") ",
                enum_descriptor->value(i)->name());
       }
       output(" = $0;\n", EnumValueSymbolInNameSpace(enum_descriptor,
                                                     enum_descriptor->value(i)));
     }
   }
 }

 }  // namespace protobuf
 }  // namespace google::hpb_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 "google/protobuf/compiler/hpb/gen_messages.h"

	#include <cstddef>
	#include <string>
	#include <vector>

	#include "google/protobuf/descriptor.pb.h"
	#include "absl/strings/ascii.h"
	#include "absl/strings/str_cat.h"
	#include "absl/strings/string_view.h"
	#include "google/protobuf/descriptor.h"
	#include "google/protobuf/compiler/hpb/gen_accessors.h"
	#include "google/protobuf/compiler/hpb/gen_enums.h"
	#include "google/protobuf/compiler/hpb/gen_extensions.h"
	#include "google/protobuf/compiler/hpb/gen_utils.h"
	#include "google/protobuf/compiler/hpb/names.h"
	#include "google/protobuf/compiler/hpb/output.h"
	#include "upb_generator/common.h"
	#include "upb_generator/file_layout.h"

	namespace google::protobuf::hpb_generator {

	namespace protobuf = ::proto2;

	void WriteModelAccessDeclaration(const protobuf::Descriptor* descriptor,
	Output& output);
	void WriteModelPublicDeclaration(
	const protobuf::Descriptor* descriptor,
	const std::vector<const protobuf::FieldDescriptor*>& file_exts,
	const std::vector<const protobuf::EnumDescriptor*>& file_enums,
	Output& output);
	void WriteExtensionIdentifiersInClassHeader(
	const protobuf::Descriptor* message,
	const std::vector<const protobuf::FieldDescriptor*>& file_exts,
	Output& output);
	void WriteModelProxyDeclaration(const protobuf::Descriptor* descriptor,
	Output& output);
	void WriteModelCProxyDeclaration(const protobuf::Descriptor* descriptor,
	Output& output);
	void WriteInternalForwardDeclarationsInHeader(
	const protobuf::Descriptor* message, Output& output);
	void WriteDefaultInstanceHeader(const protobuf::Descriptor* message,
	Output& output);
	void WriteExtensionIdentifiersImplementation(
	const protobuf::Descriptor* message,
	const std::vector<const protobuf::FieldDescriptor*>& file_exts,
	Output& output);
	void WriteUsingEnumsInHeader(
	const protobuf::Descriptor* message,
	const std::vector<const protobuf::EnumDescriptor*>& file_enums,
	Output& output);

	// Writes message class declarations into .upb.proto.h.
	//
	// For each proto Foo, FooAccess and FooProxy/FooCProxy are generated
	// that are exposed to users as Foo , Ptr<Foo> and Ptr<const Foo>.
	void WriteMessageClassDeclarations(
	const protobuf::Descriptor* descriptor,
	const std::vector<const protobuf::FieldDescriptor*>& file_exts,
	const std::vector<const protobuf::EnumDescriptor*>& file_enums,
	Output& output) {
	if (IsMapEntryMessage(descriptor)) {
	// Skip map entry generation. Low level accessors for maps are
	// generated that don't require a separate map type.
	return;
	}

	// Forward declaration of Proto Class for GCC handling of free friend method.
	output("class $0;\n", ClassName(descriptor));
	output("namespace internal {\n\n");
	WriteModelAccessDeclaration(descriptor, output);
	output("\n");
	WriteInternalForwardDeclarationsInHeader(descriptor, output);
	output("\n");
	output("} // namespace internal\n\n");
	WriteModelPublicDeclaration(descriptor, file_exts, file_enums, output);
	output("namespace internal {\n");
	WriteModelCProxyDeclaration(descriptor, output);
	WriteModelProxyDeclaration(descriptor, output);
	output("} // namespace internal\n\n");
	}

	void WriteModelAccessDeclaration(const protobuf::Descriptor* descriptor,
	Output& output) {
	output(
	R"cc(
	class $0Access {
	public:
	$0Access() {}
	$0Access($1* msg, upb_Arena* arena) : msg_(msg), arena_(arena) {
	assert(arena != nullptr);
	} // NOLINT
	$0Access(const $1* msg, upb_Arena* arena)
	: msg_(const_cast<$1*>(msg)), arena_(arena) {
	assert(arena != nullptr);
	} // NOLINT
	void* GetInternalArena() const { return arena_; }
	)cc",
	ClassName(descriptor), MessageName(descriptor));
	WriteFieldAccessorsInHeader(descriptor, output);
	WriteOneofAccessorsInHeader(descriptor, output);
	output.Indent();
	output(
	R"cc(
	private:
	friend class $2;
	friend class $0Proxy;
	friend class $0CProxy;
	friend struct ::protos::internal::PrivateAccess;
	$1* msg_;
	upb_Arena* arena_;
	)cc",
	ClassName(descriptor), MessageName(descriptor),
	QualifiedClassName(descriptor));
	output.Outdent();
	output("};\n");
	}

	std::string UnderscoresToCamelCase(absl::string_view input,
	bool cap_next_letter) {
	std::string result;

	for (size_t i = 0; i < input.size(); i++) {
	if (absl::ascii_islower(input[i])) {
	if (cap_next_letter) {
	result += absl::ascii_toupper(input[i]);
	} else {
	result += input[i];
	}
	cap_next_letter = false;
	} else if (absl::ascii_isupper(input[i])) {
	// Capital letters are left as-is.
	result += input[i];
	cap_next_letter = false;
	} else if (absl::ascii_isdigit(input[i])) {
	result += input[i];
	cap_next_letter = true;
	} else {
	cap_next_letter = true;
	}
	}
	return result;
	}

	std::string FieldConstantName(const protobuf::FieldDescriptor* field) {
	std::string field_name = UnderscoresToCamelCase(field->name(), true);
	std::string result = absl::StrCat("k", field_name, "FieldNumber");

	if (!field->is_extension() &&
	field->containing_type()->FindFieldByCamelcaseName(
	field->camelcase_name()) != field) {
	// This field's camelcase name is not unique, add field number to make it
	// unique.
	absl::StrAppend(&result, "_", field->number());
	}
	return result;
	}

	void WriteConstFieldNumbers(Output& output,
	const protobuf::Descriptor* descriptor) {
	for (auto field : FieldRange(descriptor)) {
	output("static constexpr ::uint32_t $0 = $1;\n", FieldConstantName(field),
	field->number());
	}
	output("\n\n");
	}

	void WriteModelPublicDeclaration(
	const protobuf::Descriptor* descriptor,
	const std::vector<const protobuf::FieldDescriptor*>& file_exts,
	const std::vector<const protobuf::EnumDescriptor*>& file_enums,
	Output& output) {
	output(
	R"cc(
	class $0 final : private internal::$0Access {
	public:
	using Access = internal::$0Access;
	using Proxy = internal::$0Proxy;
	using CProxy = internal::$0CProxy;

	$0();

	$0(const $0& from);
	$0& operator=(const $3& from);
	$0(const CProxy& from);
	$0(const Proxy& from);
	$0& operator=(const CProxy& from);

	$0($0&& m)
	: Access(std::exchange(m.msg_, nullptr),
	std::exchange(m.arena_, nullptr)),
	owned_arena_(std::move(m.owned_arena_)) {}

	$0& operator=($0&& m) {
	msg_ = std::exchange(m.msg_, nullptr);
	arena_ = std::exchange(m.arena_, nullptr);
	owned_arena_ = std::move(m.owned_arena_);
	return *this;
	}
	)cc",
	ClassName(descriptor),
	::upb::generator::MessageInit(descriptor->full_name()),
	MessageName(descriptor), QualifiedClassName(descriptor));

	WriteUsingAccessorsInHeader(descriptor, MessageClassType::kMessage, output);
	WriteUsingEnumsInHeader(descriptor, file_enums, output);
	WriteDefaultInstanceHeader(descriptor, output);
	WriteExtensionIdentifiersInClassHeader(descriptor, file_exts, output);
	if (descriptor->extension_range_count()) {
	// for typetrait checking
	output("using ExtendableType = $0;\n", ClassName(descriptor));
	}
	// Note: free function friends that are templates such as ::protos::Parse
	// require explicit <$2> type parameter in declaration to be able to compile
	// with gcc otherwise the compiler will fail with
	// "has not been declared within namespace" error. Even though there is a
	// namespace qualifier, cross namespace matching fails.
	output.Indent();
	output(
	R"cc(
	static const upb_MiniTable* minitable();
	using $0Access::GetInternalArena;
	)cc",
	ClassName(descriptor));
	output("\n");
	WriteConstFieldNumbers(output, descriptor);
	output(
	R"cc(
	private:
	const upb_Message* msg() const { return UPB_UPCAST(msg_); }
	upb_Message* msg() { return UPB_UPCAST(msg_); }

	$0(upb_Message* msg, upb_Arena* arena) : $0Access() {
	msg_ = ($1*)msg;
	arena_ = owned_arena_.ptr();
	upb_Arena_Fuse(arena_, arena);
	}
	::protos::Arena owned_arena_;
	friend struct ::protos::internal::PrivateAccess;
	friend Proxy;
	friend CProxy;
	friend absl::StatusOr<$2>(::protos::Parse<$2>(absl::string_view bytes,
	int options));
	friend absl::StatusOr<$2>(::protos::Parse<$2>(
	absl::string_view bytes,
	const ::protos::ExtensionRegistry& extension_registry,
	int options));
	friend upb_Arena* ::protos::internal::GetArena<$0>($0* message);
	friend upb_Arena* ::protos::internal::GetArena<$0>(::protos::Ptr<$0> message);
	friend $0(::protos::internal::MoveMessage<$0>(upb_Message* msg,
	upb_Arena* arena));
	)cc",
	ClassName(descriptor), MessageName(descriptor),
	QualifiedClassName(descriptor));
	output.Outdent();
	output("};\n\n");
	}

	void WriteModelProxyDeclaration(const protobuf::Descriptor* descriptor,
	Output& output) {
	// Foo::Proxy.
	output(
	R"cc(
	class $0Proxy final : private internal::$0Access {
	public:
	$0Proxy() = delete;
	$0Proxy(const $0Proxy& m) : internal::$0Access() {
	msg_ = m.msg_;
	arena_ = m.arena_;
	}
	$0Proxy($0* m) : internal::$0Access() {
	msg_ = m->msg_;
	arena_ = m->arena_;
	}
	$0Proxy operator=(const $0Proxy& m) {
	msg_ = m.msg_;
	arena_ = m.arena_;
	return *this;
	}
	using $0Access::GetInternalArena;
	)cc",
	ClassName(descriptor));

	WriteUsingAccessorsInHeader(descriptor, MessageClassType::kMessageProxy,
	output);
	output("\n");
	output.Indent(1);
	output(
	R"cc(
	private:
	upb_Message* msg() const { return UPB_UPCAST(msg_); }

	$0Proxy(upb_Message* msg, upb_Arena* arena)
	: internal::$0Access(($1*)msg, arena) {}
	friend $0::Proxy(::protos::CreateMessage<$0>(::protos::Arena& arena));
	friend $0::Proxy(::protos::internal::CreateMessageProxy<$0>(
	upb_Message, upb_Arena));
	friend struct ::protos::internal::PrivateAccess;
	friend class RepeatedFieldProxy;
	friend class $0CProxy;
	friend class $0Access;
	friend class ::protos::Ptr<$0>;
	friend class ::protos::Ptr<const $0>;
	static const upb_MiniTable* minitable() { return $0::minitable(); }
	friend const upb_MiniTable* ::protos::internal::GetMiniTable<$0Proxy>(
	const $0Proxy* message);
	friend const upb_MiniTable* ::protos::internal::GetMiniTable<$0Proxy>(
	::protos::Ptr<$0Proxy> message);
	friend upb_Arena* ::protos::internal::GetArena<$2>($2* message);
	friend upb_Arena* ::protos::internal::GetArena<$2>(::protos::Ptr<$2> message);
	static void Rebind($0Proxy& lhs, const $0Proxy& rhs) {
	lhs.msg_ = rhs.msg_;
	lhs.arena_ = rhs.arena_;
	}
	)cc",
	ClassName(descriptor), MessageName(descriptor),
	QualifiedClassName(descriptor));
	output.Outdent(1);
	output("};\n\n");
	}

	void WriteModelCProxyDeclaration(const protobuf::Descriptor* descriptor,
	Output& output) {
	// Foo::CProxy.
	output(
	R"cc(
	class $0CProxy final : private internal::$0Access {
	public:
	$0CProxy() = delete;
	$0CProxy(const $0* m)
	: internal::$0Access(m->msg_, ::protos::internal::GetArena(m)) {}
	$0CProxy($0Proxy m);
	using $0Access::GetInternalArena;
	)cc",
	ClassName(descriptor), MessageName(descriptor));

	WriteUsingAccessorsInHeader(descriptor, MessageClassType::kMessageCProxy,
	output);

	output.Indent(1);
	output(
	R"cc(
	private:
	using AsNonConst = $0Proxy;
	const upb_Message* msg() const { return UPB_UPCAST(msg_); }

	$0CProxy(const upb_Message* msg, upb_Arena* arena)
	: internal::$0Access(($1*)msg, arena){};
	friend struct ::protos::internal::PrivateAccess;
	friend class RepeatedFieldProxy;
	friend class ::protos::Ptr<$0>;
	friend class ::protos::Ptr<const $0>;
	static const upb_MiniTable* minitable() { return $0::minitable(); }
	friend const upb_MiniTable* ::protos::internal::GetMiniTable<$0CProxy>(
	const $0CProxy* message);
	friend const upb_MiniTable* ::protos::internal::GetMiniTable<$0CProxy>(
	::protos::Ptr<$0CProxy> message);

	static void Rebind($0CProxy& lhs, const $0CProxy& rhs) {
	lhs.msg_ = rhs.msg_;
	lhs.arena_ = rhs.arena_;
	}
	)cc",
	ClassName(descriptor), MessageName(descriptor));
	output.Outdent(1);
	output("};\n\n");
	}

	void WriteDefaultInstanceHeader(const protobuf::Descriptor* message,
	Output& output) {
	output(" static ::protos::Ptr<const $0> default_instance();\n",
	ClassName(message));
	}

	void WriteMessageImplementation(
	const protobuf::Descriptor* descriptor,
	const std::vector<const protobuf::FieldDescriptor*>& file_exts,
	Output& output) {
	bool message_is_map_entry = descriptor->options().map_entry();
	if (!message_is_map_entry) {
	// Constructor.
	output(
	R"cc(
	$0::$0() : $0Access() {
	arena_ = owned_arena_.ptr();
	msg_ = $1_new(arena_);
	}
	$0::$0(const $0& from) : $0Access() {
	arena_ = owned_arena_.ptr();
	msg_ = ($1*)::protos::internal::DeepClone(UPB_UPCAST(from.msg_), &$2, arena_);
	}
	$0::$0(const CProxy& from) : $0Access() {
	arena_ = owned_arena_.ptr();
	msg_ = ($1*)::protos::internal::DeepClone(
	::protos::internal::GetInternalMsg(&from), &$2, arena_);
	}
	$0::$0(const Proxy& from) : $0(static_cast<const CProxy&>(from)) {}
	internal::$0CProxy::$0CProxy($0Proxy m) : $0Access() {
	arena_ = m.arena_;
	msg_ = ($1*)::protos::internal::GetInternalMsg(&m);
	}
	$0& $0::operator=(const $3& from) {
	arena_ = owned_arena_.ptr();
	msg_ = ($1*)::protos::internal::DeepClone(UPB_UPCAST(from.msg_), &$2, arena_);
	return *this;
	}
	$0& $0::operator=(const CProxy& from) {
	arena_ = owned_arena_.ptr();
	msg_ = ($1*)::protos::internal::DeepClone(
	::protos::internal::GetInternalMsg(&from), &$2, arena_);
	return *this;
	}
	)cc",
	ClassName(descriptor), MessageName(descriptor),
	::upb::generator::MessageInit(descriptor->full_name()),
	QualifiedClassName(descriptor));
	output("\n");
	// Minitable
	output(
	R"cc(
	const upb_MiniTable* $0::minitable() { return &$1; }
	)cc",
	ClassName(descriptor),
	::upb::generator::MessageInit(descriptor->full_name()));
	output("\n");
	}

	WriteAccessorsInSource(descriptor, output);

	if (!message_is_map_entry) {
	output(
	R"cc(
	struct $0DefaultTypeInternal {
	$1* msg;
	upb_Arena* arena;
	};
	static $0DefaultTypeInternal _$0DefaultTypeBuilder() {
	upb_Arena* arena = upb_Arena_New();
	return $0DefaultTypeInternal{$1_new(arena), arena};
	}
	$0DefaultTypeInternal _$0_default_instance_ = _$0DefaultTypeBuilder();
	)cc",
	ClassName(descriptor), MessageName(descriptor));

	output(
	R"cc(
	::protos::Ptr<const $0> $0::default_instance() {
	return ::protos::internal::CreateMessage<$0>(
	(upb_Message *)_$0_default_instance_.msg,
	_$0_default_instance_.arena);
	}
	)cc",
	ClassName(descriptor));

	WriteExtensionIdentifiersImplementation(descriptor, file_exts, output);
	}
	}

	void WriteInternalForwardDeclarationsInHeader(
	const protobuf::Descriptor* message, Output& output) {
	// Write declaration for internal re-usable default_instance without
	// leaking implementation.
	output(
	R"cc(
	struct $0DefaultTypeInternal;
	extern $0DefaultTypeInternal _$0_default_instance_;
	)cc",
	ClassName(message));
	}

	void WriteExtensionIdentifiersInClassHeader(
	const protobuf::Descriptor* message,
	const std::vector<const protobuf::FieldDescriptor*>& file_exts,
	Output& output) {
	for (auto* ext : file_exts) {
	if (ext->extension_scope() &&
	ext->extension_scope()->full_name() == message->full_name()) {
	WriteExtensionIdentifierHeader(ext, output);
	}
	}
	}

	void WriteExtensionIdentifiersImplementation(
	const protobuf::Descriptor* message,
	const std::vector<const protobuf::FieldDescriptor*>& file_exts,
	Output& output) {
	for (auto* ext : file_exts) {
	if (ext->extension_scope() &&
	ext->extension_scope()->full_name() == message->full_name()) {
	WriteExtensionIdentifier(ext, output);
	}
	}
	}

	void WriteUsingEnumsInHeader(
	const protobuf::Descriptor* message,
	const std::vector<const protobuf::EnumDescriptor*>& file_enums,
	Output& output) {
	for (auto* enum_descriptor : file_enums) {
	std::string enum_type_name = EnumTypeName(enum_descriptor);
	std::string enum_resolved_type_name =
	enum_descriptor->file()->package().empty() &&
	enum_descriptor->containing_type() == nullptr
	? absl::StrCat(kNoPackageNamePrefix,
	ToCIdent(enum_descriptor->name()))
	: enum_type_name;
	if (enum_descriptor->containing_type() == nullptr \|\|
	enum_descriptor->containing_type()->full_name() !=
	message->full_name()) {
	continue;
	}
	output("using $0", enum_descriptor->name());
	if (enum_descriptor->options().deprecated()) {
	output(" ABSL_DEPRECATED(\"Proto enum $0\")", enum_descriptor->name());
	}
	output(" = $0;", enum_resolved_type_name);
	output("\n");
	int value_count = enum_descriptor->value_count();
	for (int i = 0; i < value_count; i++) {
	output("static constexpr $0 $1", enum_descriptor->name(),
	enum_descriptor->value(i)->name());
	if (enum_descriptor->options().deprecated() \|\|
	enum_descriptor->value(i)->options().deprecated()) {
	output(" ABSL_DEPRECATED(\"Proto enum value $0\") ",
	enum_descriptor->value(i)->name());
	}
	output(" = $0;\n", EnumValueSymbolInNameSpace(enum_descriptor,
	enum_descriptor->value(i)));
	}
	}
	}

	} // namespace protobuf
	} // namespace google::hpb_generator