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 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  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
 
 // Author: kenton@google.com (Kenton Varda)
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
 #ifndef GOOGLE_PROTOBUF_COMPILER_CPP_FIELD_H__
 #define GOOGLE_PROTOBUF_COMPILER_CPP_FIELD_H__
 
 #include <cstddef>
 #include <cstdint>
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "absl/container/flat_hash_map.h"
 #include "absl/log/absl_check.h"
 #include "absl/strings/string_view.h"
 #include "absl/types/optional.h"
 #include "absl/types/span.h"
 #include "google/protobuf/compiler/cpp/helpers.h"
 #include "google/protobuf/compiler/cpp/options.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/io/printer.h"
 
 namespace google {
 namespace protobuf {
 namespace compiler {
 namespace cpp {
 
 // Customization points for each field codegen type. See FieldGenerator to
 // see how each of these functions is used.
 //
 // TODO: Make every function except the dtor in this generator
 // non-pure-virtual. A generator with no implementation should be able to
 // automatically not contribute any code to the message it is part of, as a
 // matter of clean composability.
 class FieldGeneratorBase {
  public:
   // `GeneratorFunction` defines a subset of generator functions that may have
   // additional optimizations or requirements such as 'uses a local `arena`
   // variable instead of calling GetArena()'
   enum class GeneratorFunction { kMergeFrom };
 
   FieldGeneratorBase(const FieldDescriptor* field, const Options& options,
                      MessageSCCAnalyzer* scc_analyzer);
 
   FieldGeneratorBase(const FieldGeneratorBase&) = delete;
   FieldGeneratorBase& operator=(const FieldGeneratorBase&) = delete;
 
   virtual ~FieldGeneratorBase() = 0;
 
   // Returns true if this field should be placed in the cold 'Split' section.
   bool should_split() const { return should_split_; }
 
   // Returns true if this field is trivial. (int, float, double, enum, bool)
   bool is_trivial() const { return is_trivial_; }
 
   // Returns true if the field value itself is trivial, i.e., the field is
   // trivial, or a (raw) pointer value to a singular, non lazy message.
   bool has_trivial_value() const { return has_trivial_value_; }
 
   // Returns true if the provided field has a trivial zero default.
   // I.e., the field can be initialized with `memset(&field, 0, sizeof(field))`
   bool has_trivial_zero_default() const { return has_trivial_zero_default_; }
 
   // Returns true if the provided field can be initialized with `= {}`.
   bool has_brace_default_assign() const { return has_brace_default_assign_; }
 
   // Returns true if the field is a singular or repeated message.
   // This includes group message types. To explicitly check if a message
   // type is a group type, use the `is_group()` function,
   bool is_message() const { return is_message_; }
 
   // Returns true if the field is a group message field (TYPE_GROUP).
   bool is_group() const { return is_group_; }
 
   // Returns true if the field is a weak message
   bool is_weak() const { return is_weak_; }
 
   // Returns true if the field is a lazy message.
   bool is_lazy() const { return is_lazy_; }
 
   // Returns true if the field is a foreign message field.
   bool is_foreign() const { return is_foreign_; }
 
   // Returns true if the field is a string field.
   bool is_string() const { return is_string_; }
 
   // Returns true if the field API uses bytes (void) instead of chars.
   bool is_bytes() const { return is_bytes_; }
 
   // Returns true if this field is part of a oneof field.
   bool is_oneof() const { return is_oneof_; }
 
   // Returns true if the field should be inlined instead of dynamically
   // allocated. Applies to string and message value.
   bool is_inlined() const { return is_inlined_; }
 
   // Returns true if this field has an appropriate default constexpr
   // constructor. i.e., there is no need for an explicit initializer.
   bool has_default_constexpr_constructor() const {
     return has_default_constexpr_constructor_;
   }
 
   // Returns true if this generator requires an 'arena' parameter on the
   // given generator function.
   virtual bool RequiresArena(GeneratorFunction) const { return false; }
 
   virtual std::vector<io::Printer::Sub> MakeVars() const { return {}; }
 
   virtual void GeneratePrivateMembers(io::Printer* p) const = 0;
 
   virtual void GenerateStaticMembers(io::Printer* p) const {}
 
   virtual void GenerateAccessorDeclarations(io::Printer* p) const = 0;
 
   virtual void GenerateInlineAccessorDefinitions(io::Printer* p) const = 0;
 
   virtual void GenerateNonInlineAccessorDefinitions(io::Printer* p) const {}
 
   virtual void GenerateClearingCode(io::Printer* p) const = 0;
 
   virtual void GenerateMessageClearingCode(io::Printer* p) const {
     GenerateClearingCode(p);
   }
 
   virtual void GenerateMergingCode(io::Printer* p) const = 0;
 
   virtual void GenerateCopyConstructorCode(io::Printer* p) const;
 
   virtual void GenerateSwappingCode(io::Printer* p) const = 0;
 
   virtual void GenerateConstructorCode(io::Printer* p) const = 0;
 
   virtual void GenerateDestructorCode(io::Printer* p) const {}
 
   virtual void GenerateArenaDestructorCode(io::Printer* p) const {
     ABSL_CHECK(NeedsArenaDestructor() == ArenaDtorNeeds::kNone)
         << field_->cpp_type_name();
   }
 
   // Generates constexpr member initialization code, e.g.: `foo_{5}`.
   // The default implementation generates the following code:
   // - repeated fields and maps: `field_{}`
   // - all other fields: `field_{<default value>}`
   virtual void GenerateMemberConstexprConstructor(io::Printer* p) const;
 
   // Generates member initialization code, e.g.: `foo_(5)`.
   // The default implementation generates the following code:
   // - repeated fields and maps: `field_{visibility, arena}`
   // - split repeated fields (RawPtr): `field_{}`
   // - all other fields: `field_{<default value>}`
   virtual void GenerateMemberConstructor(io::Printer* p) const;
 
   // Generates member copy initialization code, e.g.: `foo_(5)`.
   // The default implementation generates the following code:
   // - repeated fields and maps: `field_{visibility, arena, from.field_}`
   // - all other fields: `field_{from.field_}`
   virtual void GenerateMemberCopyConstructor(io::Printer* p) const;
 
   // Generates 'placement new' copy construction code used to
   // explicitly copy initialize oneof field values.
   // The default implementation checks the current field to not be repeated,
   // an extension or a map, and generates the following code:
   // - `field_ = from.field_`
   virtual void GenerateOneofCopyConstruct(io::Printer* p) const;
 
   virtual void GenerateAggregateInitializer(io::Printer* p) const;
 
   virtual void GenerateConstexprAggregateInitializer(io::Printer* p) const;
 
   virtual void GenerateCopyAggregateInitializer(io::Printer* p) const;
 
   virtual void GenerateSerializeWithCachedSizesToArray(
       io::Printer* p) const = 0;
 
   virtual void GenerateByteSize(io::Printer* p) const = 0;
 
   virtual void GenerateIsInitialized(io::Printer* p) const {
     ABSL_CHECK(!NeedsIsInitialized());
   }
   virtual bool NeedsIsInitialized() const { return false; }
 
   virtual bool IsInlined() const { return false; }
 
   virtual ArenaDtorNeeds NeedsArenaDestructor() const {
     return ArenaDtorNeeds::kNone;
   }
 
  protected:
   const FieldDescriptor* field_;
   const Options& options_;
   MessageSCCAnalyzer* scc_;
   absl::flat_hash_map<absl::string_view, std::string> variables_;
 
  private:
   bool should_split_ = false;
   bool is_trivial_ = false;
   bool has_trivial_value_ = false;
   bool has_trivial_zero_default_ = false;
   bool has_brace_default_assign_ = false;
   bool is_message_ = false;
   bool is_group_ = false;
   bool is_string_ = false;
   bool is_bytes_ = false;
   bool is_inlined_ = false;
   bool is_foreign_ = false;
   bool is_lazy_ = false;
   bool is_weak_ = false;
   bool is_oneof_ = false;
   bool has_default_constexpr_constructor_ = false;
 };
 
 inline FieldGeneratorBase::~FieldGeneratorBase() = default;
 
 class FieldGenerator {
  private:
   // This function must be defined here so that the inline definitions below
   // can see it, which is required because it has deduced return type.
   auto PushVarsForCall(io::Printer* p) const {
     // NOTE: we use a struct here because:
     // * We want to ensure that order of evaluation below is well-defined,
     //   which {...} guarantees but (...) does not.
     // * We do not require C++17 as of writing and therefore cannot use
     //   std::tuple with CTAD.
     // * std::make_tuple uses (...), not {...}.
     struct Vars {
       decltype(p->WithVars(field_vars_)) cleanup1;
       decltype(p->WithVars(tracker_vars_)) cleanup2;
       decltype(p->WithVars(per_generator_vars_)) cleanup3;
     };
 
     return Vars{p->WithVars(field_vars_), p->WithVars(tracker_vars_),
                 p->WithVars(per_generator_vars_)};
   }
 
  public:
   using GeneratorFunction = FieldGeneratorBase::GeneratorFunction;
 
   FieldGenerator(const FieldGenerator&) = delete;
   FieldGenerator& operator=(const FieldGenerator&) = delete;
   FieldGenerator(FieldGenerator&&) = default;
   FieldGenerator& operator=(FieldGenerator&&) = default;
 
   // Properties: see FieldGeneratorBase for documentation
   bool should_split() const { return impl_->should_split(); }
   bool is_trivial() const { return impl_->is_trivial(); }
   bool has_trivial_value() const { return impl_->has_trivial_value(); }
   bool has_trivial_zero_default() const {
     return impl_->has_trivial_zero_default();
   }
   bool has_brace_default_assign() const {
     return impl_->has_brace_default_assign();
   }
   bool is_message() const { return impl_->is_message(); }
   bool is_group() const { return impl_->is_group(); }
   bool is_weak() const { return impl_->is_weak(); }
   bool is_lazy() const { return impl_->is_lazy(); }
   bool is_foreign() const { return impl_->is_foreign(); }
   bool is_string() const { return impl_->is_string(); }
   bool is_bytes() const { return impl_->is_bytes(); }
   bool is_oneof() const { return impl_->is_oneof(); }
   bool is_inlined() const { return impl_->is_inlined(); }
   bool has_default_constexpr_constructor() const {
     return impl_->has_default_constexpr_constructor();
   }
 
   // Requirements: see FieldGeneratorBase for documentation
   bool RequiresArena(GeneratorFunction function) const {
     return impl_->RequiresArena(function);
   }
 
   // Prints private members needed to represent this field.
   //
   // These are placed inside the class definition.
   void GeneratePrivateMembers(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GeneratePrivateMembers(p);
   }
 
   // Prints static members needed to represent this field.
   //
   // These are placed inside the class definition.
   void GenerateStaticMembers(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateStaticMembers(p);
   }
 
   void GenerateMemberConstructor(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateMemberConstructor(p);
   }
 
   void GenerateMemberCopyConstructor(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateMemberCopyConstructor(p);
   }
 
   void GenerateOneofCopyConstruct(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateOneofCopyConstruct(p);
   }
 
   void GenerateMemberConstexprConstructor(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateMemberConstexprConstructor(p);
   }
 
   // Generates declarations for all of the accessor functions related to this
   // field.
   //
   // These are placed inside the class definition.
   void GenerateAccessorDeclarations(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateAccessorDeclarations(p);
   }
 
   // Generates inline definitions of accessor functions for this field.
   //
   // These are placed in namespace scope in the header after all class
   // definitions.
   void GenerateInlineAccessorDefinitions(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateInlineAccessorDefinitions(p);
   }
 
   // Generates definitions of accessors that aren't inlined.
   //
   // These are placed in namespace scope in the .cc file.
   void GenerateNonInlineAccessorDefinitions(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateNonInlineAccessorDefinitions(p);
   }
 
   // Generates statements which clear the field.
   //
   // This is used to define the clear_$name$() method.
   void GenerateClearingCode(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateClearingCode(p);
   }
 
   // Generates statements which clear the field as part of the Clear() method
   // for the whole message.
   //
   // For message types which have field presence bits,
   // MessageGenerator::GenerateClear will have already checked the presence
   // bits.
   void GenerateMessageClearingCode(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateMessageClearingCode(p);
   }
 
   // Generates statements which merge the contents of the field from the current
   // message to the target message, which is stored in the generated code
   // variable `from`.
   //
   // This is used to fill in the MergeFrom method for the whole message.
   //
   // Details of this usage can be found in message.cc under the
   // GenerateMergeFrom method.
   void GenerateMergingCode(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateMergingCode(p);
   }
 
   // Generates a copy constructor
   //
   // TODO: Document this properly.
   void GenerateCopyConstructorCode(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateCopyConstructorCode(p);
   }
 
   // Generates statements which swap this field and the corresponding field of
   // another message, which is stored in the generated code variable `other`.
   //
   // This is used to define the Swap method. Details of usage can be found in
   // message.cc under the GenerateSwap method.
   void GenerateSwappingCode(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateSwappingCode(p);
   }
 
   // Generates initialization code for private members declared by
   // GeneratePrivateMembers().
   //
   // These go into the message class's SharedCtor() method, invoked by each of
   // the generated constructors.
   void GenerateConstructorCode(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateConstructorCode(p);
   }
 
   // Generates any code that needs to go in the class's SharedDtor() method,
   // invoked by the destructor.
   void GenerateDestructorCode(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateDestructorCode(p);
   }
 
   // Generates a manual destructor invocation for use when the message is on an
   // arena.
   //
   // The code that this method generates will be executed inside a
   // shared-for-the-whole-message-class method registered with OwnDestructor().
   void GenerateArenaDestructorCode(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateArenaDestructorCode(p);
   }
 
   // Generates initialization code for private members declared by
   // GeneratePrivateMembers().
   //
   // These go into the SharedCtor's aggregate initialization of the _impl_
   // struct and must follow the syntax `decltype($field$){$default$}`.
   // Does not include `:` or `,` separators. Default values should be specified
   // here when possible.
   //
   // NOTE: We use `decltype($field$)` for both explicit construction and the
   // fact that it's self-documenting. Pre-C++17, copy elision isn't guaranteed
   // in aggregate initialization so a valid copy/move constructor must exist
   // (even though it's not used). Because of this, we need to comment out the
   // decltype and fallback to implicit construction.
   void GenerateAggregateInitializer(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateAggregateInitializer(p);
   }
 
   // Generates constinit initialization code for private members declared by
   // GeneratePrivateMembers().
   //
   // These go into the constexpr constructor's aggregate initialization of the
   // _impl_ struct and must follow the syntax `/*decltype($field$)*/{}` (see
   // above). Does not include `:` or `,` separators.
   void GenerateConstexprAggregateInitializer(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateConstexprAggregateInitializer(p);
   }
 
   // Generates copy initialization code for private members declared by
   // GeneratePrivateMembers().
   //
   // These go into the copy constructor's aggregate initialization of the _impl_
   // struct and must follow the syntax `decltype($field$){from.$field$}` (see
   // above). Does not include `:` or `,` separators.
   void GenerateCopyAggregateInitializer(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateCopyAggregateInitializer(p);
   }
 
   // Generates statements to serialize this field directly to the array
   // `target`, which are placed within the message's
   // SerializeWithCachedSizesToArray() method.
   //
   // This must also advance `target` past the written bytes.
   void GenerateSerializeWithCachedSizesToArray(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateSerializeWithCachedSizesToArray(p);
   }
 
   // Generates statements to compute the serialized size of this field, which
   // are placed in the message's ByteSize() method.
   void GenerateByteSize(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateByteSize(p);
   }
 
   // Generates lines to call IsInitialized() for eligible message fields. Non
   // message fields won't need to override this function.
   void GenerateIsInitialized(io::Printer* p) const {
     auto vars = PushVarsForCall(p);
     impl_->GenerateIsInitialized(p);
   }
 
   bool NeedsIsInitialized() const { return impl_->NeedsIsInitialized(); }
 
   // TODO: Document this properly.
   bool IsInlined() const { return impl_->IsInlined(); }
 
   // TODO: Document this properly.
   ArenaDtorNeeds NeedsArenaDestructor() const {
     return impl_->NeedsArenaDestructor();
   }
 
  private:
   friend class FieldGeneratorTable;
   FieldGenerator(const FieldDescriptor* field, const Options& options,
                  MessageSCCAnalyzer* scc_analyzer,
                  absl::optional<uint32_t> hasbit_index,
                  absl::optional<uint32_t> inlined_string_index);
 
   std::unique_ptr<FieldGeneratorBase> impl_;
   std::vector<io::Printer::Sub> field_vars_;
   std::vector<io::Printer::Sub> tracker_vars_;
   std::vector<io::Printer::Sub> per_generator_vars_;
 };
 
 // Convenience class which constructs FieldGeneratorBases for a Descriptor.
 class FieldGeneratorTable {
  public:
   explicit FieldGeneratorTable(const Descriptor* descriptor)
       : descriptor_(descriptor) {}
 
   FieldGeneratorTable(const FieldGeneratorTable&) = delete;
   FieldGeneratorTable& operator=(const FieldGeneratorTable&) = delete;
 
   void Build(const Options& options, MessageSCCAnalyzer* scc_analyzer,
              absl::Span<const int32_t> has_bit_indices,
              absl::Span<const int32_t> inlined_string_indices);
 
   const FieldGenerator& get(const FieldDescriptor* field) const {
     ABSL_CHECK_EQ(field->containing_type(), descriptor_);
     ABSL_DCHECK_GE(field->index(), 0);
     return fields_[static_cast<size_t>(field->index())];
   }
 
  private:
   const Descriptor* descriptor_;
   std::vector<FieldGenerator> fields_;
 };
 
 // Returns variables common to all fields.
 //
 // TODO: Make this function .cc-private.
 std::vector<io::Printer::Sub> FieldVars(const FieldDescriptor* field,
                                         const Options& opts);
 }  // namespace cpp
 }  // namespace compiler
 }  // namespace protobuf
 }  // namespace google
 
 #endif  // GOOGLE_PROTOBUF_COMPILER_CPP_FIELD_H__

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