message_schema.h

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// Copyright (c) Space-ng, inc. All rights reserved.
#pragma once
 
#include "sol3/core/fb_json.h"
 
#include <flatbuffers/idl.h>
#include <flatbuffers/reflection.h>
#include <flatbuffers/stl_emulation.h>
 
namespace sol3::core {
 
class MessageSchema {
 public:
  enum class EvolutionPolicy {
    ALWAYS,
    FORWARDS_COMPATIBLE
  };
 
  MessageSchema() = default;
  MessageSchema(
      flatbuffers::span<uint8_t const> schema_buffer, EvolutionPolicy policy);
 
  flatbuffers::span<uint8_t const> schemaBufferSpan() const {
    return flatbuffers::span<uint8_t const>(
        schema_buffer_->data(), schema_buffer_->size());
  }
 
  reflection::Schema const* table() const;
 
  bool verify(flatbuffers::span<uint8_t const> buffer) const;
 
  operator bool() const;
 
  flatbuffers::Parser const& parser(
      JsonFormat format = JsonFormat::SINGLE_LINE) const;
 
  std::string toJson(
      flatbuffers::span<uint8_t const> buffer,
      JsonFormat format = JsonFormat::SINGLE_LINE) const;
 
  flatbuffers::span<uint8_t const> fromJson(std::string const& json_str);
 
  bool operator==(MessageSchema const& schema) const;
  bool operator!=(MessageSchema const& schema) const {
    return !(*this == schema);
  }
 
  std::string conformsTo(MessageSchema const& previous_schema) const;
 
  void evolve(MessageSchema const& new_schema);
 
  EvolutionPolicy policy() const { return policy_; }
 
  std::string fileIdentifierString() const;
 
  uint32_t fileIdentifier() const;
 
 private:
  std::shared_ptr<std::vector<uint8_t>> schema_buffer_;
  std::shared_ptr<flatbuffers::Parser> parser_;
  EvolutionPolicy policy_ = EvolutionPolicy::ALWAYS;
};
}  // namespace sol3::core