draconisplusplus/include/rfl/cbor/write.hpp

#ifndef RFL_CBOR_WRITE_HPP_
#define RFL_CBOR_WRITE_HPP_

#include <cbor.h>
#include <cstdint>
#include <ostream>
#include <sstream>
#include <string>
#include <utility>

#include "../parsing/Parent.hpp"
#include "Parser.hpp"

namespace rfl {
  namespace cbor {

    template <class... Ps>
    void write_into_buffer(
        const auto&        _obj,
        CborEncoder*       _encoder,
        std::vector<char>* _buffer
    ) noexcept {
      using T          = std::remove_cvref_t<decltype(_obj)>;
      using ParentType = parsing::Parent<Writer>;
      cbor_encoder_init(
          _encoder, reinterpret_cast<uint8_t*>(_buffer->data()),
          _buffer->size(), 0
      );
      const auto writer = Writer(_encoder);
      Parser<T, Processors<Ps...>>::write(
          writer, _obj, typename ParentType::Root {}
      );
    }

    /// Returns CBOR bytes.
    template <class... Ps>
    std::vector<char> write(const auto& _obj) noexcept {
      std::vector<char> buffer(4096);
      CborEncoder       encoder;
      write_into_buffer<Ps...>(_obj, &encoder, &buffer);
      const auto total_bytes_needed =
          buffer.size() + cbor_encoder_get_extra_bytes_needed(&encoder);
      if (total_bytes_needed != buffer.size()) {
        buffer.resize(total_bytes_needed);
        write_into_buffer<Ps...>(_obj, &encoder, &buffer);
      }
      const auto length = cbor_encoder_get_buffer_size(
          &encoder, reinterpret_cast<uint8_t*>(buffer.data())
      );
      buffer.resize(length);
      return buffer;
    }

    /// Writes a CBOR into an ostream.
    template <class... Ps>
    std::ostream& write(const auto& _obj, std::ostream& _stream) noexcept {
      auto buffer = write<Ps...>(_obj);
      _stream.write(buffer.data(), buffer.size());
      return _stream;
    }

  } // namespace cbor
} // namespace rfl

#endif