Function read_map_data_slow

cpp/fory/serialization/map_serializer.h:699–948

/// Read map data for polymorphic or shared-ref maps
template <typename K, typename V, typename MapType>
inline MapType read_map_data_slow(ReadContext &ctx, uint32_t length) {
  MapType result;
  if (length == 0) {
    return result;
  }
  if (FORY_PREDICT_FALSE(!reserve_map(result, ctx, length))) {
    return result;
  }

  constexpr bool key_is_polymorphic = is_polymorphic_v<K>;
  constexpr bool val_is_polymorphic = is_polymorphic_v<V>;
  constexpr bool key_is_shared_ref = is_shared_ref_v<K>;
  constexpr bool val_is_shared_ref = is_shared_ref_v<V>;

  uint32_t len_counter = 0;

  while (len_counter < length) {
    uint8_t header = ctx.read_uint8(ctx.error());
    if (FORY_PREDICT_FALSE(ctx.has_error())) {
      return MapType{};
    }

    // Handle null entries
    if ((header & KEY_NULL) && (header & VALUE_NULL)) {
      // Both key and value are null - insert with default-constructed values
      result.emplace(K{}, V{});
      len_counter++;
      continue;
    }

    if (header & KEY_NULL) {
      // Null key, non-null value
      // Java writes: chunk_header, then ref_flag, then type_info, then data
      bool track_value_ref = (header & TRACKING_VALUE_REF) != 0;
      bool value_declared = (header & DECL_VALUE_TYPE) != 0;

      // Consume ref flag first if tracking refs
      bool has_value = true;
      if (track_value_ref || val_is_shared_ref) {
        has_value = read_null_only_flag(ctx, RefMode::NullOnly);
        if (FORY_PREDICT_FALSE(ctx.has_error())) {
          return MapType{};
        }
      }

      if (!has_value) {
        // Value is null reference
        result.emplace(K{}, V{});
        len_counter++;
        continue;
      }

      // Now read type info if needed
      const TypeInfo *value_type_info = nullptr;
      if (!value_declared || val_is_polymorphic) {
        if constexpr (val_is_polymorphic) {
          value_type_info = read_polymorphic_type_info(ctx);
          if (FORY_PREDICT_FALSE(ctx.has_error())) {