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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.
 //
 // Defines an implementation of Message which can emulate types which are not
 // known at compile-time.
 
 #ifndef GOOGLE_PROTOBUF_DYNAMIC_MESSAGE_H__
 #define GOOGLE_PROTOBUF_DYNAMIC_MESSAGE_H__
 
 #include <algorithm>
 #include <cstddef>
 #include <cstdint>
 #include <string>
 #include <vector>
 
 #include "absl/container/flat_hash_map.h"
 #include "absl/log/absl_log.h"
 #include "absl/synchronization/mutex.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/message.h"
 #include "google/protobuf/reflection.h"
 #include "google/protobuf/repeated_field.h"
 
 #ifdef SWIG
 #error "You cannot SWIG proto headers"
 #endif
 
 // Must be included last.
 #include "google/protobuf/port_def.inc"
 
 namespace google {
 namespace protobuf {
 
 // Defined in other files.
 class Descriptor;      // descriptor.h
 class DescriptorPool;  // descriptor.h
 
 // Constructs implementations of Message which can emulate types which are not
 // known at compile-time.
 //
 // Sometimes you want to be able to manipulate protocol types that you don't
 // know about at compile time.  It would be nice to be able to construct
 // a Message object which implements the message type given by any arbitrary
 // Descriptor.  DynamicMessage provides this.
 //
 // As it turns out, a DynamicMessage needs to construct extra
 // information about its type in order to operate.  Most of this information
 // can be shared between all DynamicMessages of the same type.  But, caching
 // this information in some sort of global map would be a bad idea, since
 // the cached information for a particular descriptor could outlive the
 // descriptor itself.  To avoid this problem, DynamicMessageFactory
 // encapsulates this "cache".  All DynamicMessages of the same type created
 // from the same factory will share the same support data.  Any Descriptors
 // used with a particular factory must outlive the factory.
 //
 // The thread safety for this class is subtle, see comments around GetPrototype
 // for details
 class PROTOBUF_EXPORT DynamicMessageFactory : public MessageFactory {
  public:
   // Construct a DynamicMessageFactory that will search for extensions in
   // the DescriptorPool in which the extendee is defined.
   DynamicMessageFactory();
 
   // Construct a DynamicMessageFactory that will search for extensions in
   // the given DescriptorPool.
   //
   // DEPRECATED:  Use CodedInputStream::SetExtensionRegistry() to tell the
   //   parser to look for extensions in an alternate pool.  However, note that
   //   this is almost never what you want to do.  Almost all users should use
   //   the zero-arg constructor.
 #ifndef PROTOBUF_FUTURE_BREAKING_CHANGES
   explicit
 #endif
       DynamicMessageFactory(const DescriptorPool* pool);
   DynamicMessageFactory(const DynamicMessageFactory&) = delete;
   DynamicMessageFactory& operator=(const DynamicMessageFactory&) = delete;
 
   ~DynamicMessageFactory() override;
 
   // Call this to tell the DynamicMessageFactory that if it is given a
   // Descriptor d for which:
   //   d->file()->pool() == DescriptorPool::generated_pool(),
   // then it should delegate to MessageFactory::generated_factory() instead
   // of constructing a dynamic implementation of the message.  In theory there
   // is no down side to doing this, so it may become the default in the future.
   void SetDelegateToGeneratedFactory(bool enable) {
     delegate_to_generated_factory_ = enable;
   }
 
   // implements MessageFactory ---------------------------------------
 
   // Given a Descriptor, constructs the default (prototype) Message of that
   // type.  You can then call that message's New() method to construct a
   // mutable message of that type.
   //
   // Calling this method twice with the same Descriptor returns the same
   // object.  The returned object remains property of the factory and will
   // be destroyed when the factory is destroyed.  Also, any objects created
   // by calling the prototype's New() method share some data with the
   // prototype, so these must be destroyed before the DynamicMessageFactory
   // is destroyed.
   //
   // The given descriptor must be non-null and outlive the returned message, and
   // hence must outlive the DynamicMessageFactory.
   //
   // The method is thread-safe.
   const Message* GetPrototype(const Descriptor* type) override;
 
  private:
   const DescriptorPool* pool_;
   bool delegate_to_generated_factory_;
 
   struct TypeInfo;
   absl::flat_hash_map<const Descriptor*, const TypeInfo*> prototypes_;
   mutable absl::Mutex prototypes_mutex_;
 
   friend class DynamicMessage;
   const Message* GetPrototypeNoLock(const Descriptor* type);
 };
 
 // Helper for computing a sorted list of map entries via reflection.
 class PROTOBUF_EXPORT DynamicMapSorter {
  public:
   static std::vector<const Message*> Sort(const Message& message, int map_size,
                                           const Reflection* reflection,
                                           const FieldDescriptor* field) {
     std::vector<const Message*> result;
     result.reserve(map_size);
     RepeatedFieldRef<Message> map_field =
         reflection->GetRepeatedFieldRef<Message>(message, field);
     for (auto it = map_field.begin(); it != map_field.end(); ++it) {
       result.push_back(&*it);
     }
     MapEntryMessageComparator comparator(field->message_type());
     std::stable_sort(result.begin(), result.end(), comparator);
     // Complain if the keys aren't in ascending order.
 #ifndef NDEBUG
     for (size_t j = 1; j < static_cast<size_t>(map_size); ++j) {
       if (!comparator(result[j - 1], result[j])) {
         ABSL_LOG(ERROR) << (comparator(result[j], result[j - 1])
                                 ? "internal error in map key sorting"
                                 : "map keys are not unique");
       }
     }
 #endif
     return result;
   }
 
  private:
   class PROTOBUF_EXPORT MapEntryMessageComparator {
    public:
     explicit MapEntryMessageComparator(const Descriptor* descriptor)
         : field_(descriptor->field(0)) {}
 
     bool operator()(const Message* a, const Message* b) {
       const Reflection* reflection = a->GetReflection();
       switch (field_->cpp_type()) {
         case FieldDescriptor::CPPTYPE_BOOL: {
           bool first = reflection->GetBool(*a, field_);
           bool second = reflection->GetBool(*b, field_);
           return first < second;
         }
         case FieldDescriptor::CPPTYPE_INT32: {
           int32_t first = reflection->GetInt32(*a, field_);
           int32_t second = reflection->GetInt32(*b, field_);
           return first < second;
         }
         case FieldDescriptor::CPPTYPE_INT64: {
           int64_t first = reflection->GetInt64(*a, field_);
           int64_t second = reflection->GetInt64(*b, field_);
           return first < second;
         }
         case FieldDescriptor::CPPTYPE_UINT32: {
           uint32_t first = reflection->GetUInt32(*a, field_);
           uint32_t second = reflection->GetUInt32(*b, field_);
           return first < second;
         }
         case FieldDescriptor::CPPTYPE_UINT64: {
           uint64_t first = reflection->GetUInt64(*a, field_);
           uint64_t second = reflection->GetUInt64(*b, field_);
           return first < second;
         }
         case FieldDescriptor::CPPTYPE_STRING: {
           std::string first = reflection->GetString(*a, field_);
           std::string second = reflection->GetString(*b, field_);
           return first < second;
         }
         default:
           ABSL_DLOG(FATAL) << "Invalid key for map field.";
           return true;
       }
     }
 
    private:
     const FieldDescriptor* field_;
   };
 };
 
 }  // namespace protobuf
 }  // namespace google
 
 #include "google/protobuf/port_undef.inc"
 
 #endif  // GOOGLE_PROTOBUF_DYNAMIC_MESSAGE_H__

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