static int ArrowIpcDecoderSetTypeUnion()

in extensions/nanoarrow_ipc/src/nanoarrow/nanoarrow_ipc_decoder.c [620:698]
66 lines of code
10 McCabe index (conditional complexity)

static int ArrowIpcDecoderSetTypeUnion(struct ArrowSchema* schema,
                                       flatbuffers_generic_t type_generic,
                                       int64_t n_children, struct ArrowError* error) {
  ns(Union_table_t) type = (ns(Union_table_t))type_generic;
  int union_mode = ns(Union_mode(type));

  if (n_children < 0 || n_children > 127) {
    ArrowErrorSet(error,
                  "Expected between 0 and 127 children for Union type but found %ld",
                  (long)n_children);
    return EINVAL;
  }

  // Max valid typeIds size is 127; the longest single ID that could be present here
  // is -INT_MIN (11 chars). With commas and the prefix the max size would be
  // 1527 characters. (Any ids outside the range 0...127 are unlikely to be valid
  // elsewhere but they could in theory be present here).
  char union_types_str[2048];
  memset(union_types_str, 0, sizeof(union_types_str));
  char* format_cursor = union_types_str;
  int format_out_size = sizeof(union_types_str);
  int n_chars = 0;

  const char* format_prefix;
  switch (union_mode) {
    case ns(UnionMode_Sparse):
      n_chars = snprintf(format_cursor, format_out_size, "+us:");
      format_cursor += n_chars;
      format_out_size -= n_chars;
      break;
    case ns(UnionMode_Dense):
      n_chars = snprintf(format_cursor, format_out_size, "+ud:");
      format_cursor += n_chars;
      format_out_size -= n_chars;
      break;
    default:
      ArrowErrorSet(error, "Unexpected Union UnionMode value: %d", (int)union_mode);
      return EINVAL;
  }

  if (ns(Union_typeIds_is_present(type))) {
    flatbuffers_int32_vec_t type_ids = ns(Union_typeIds(type));
    int64_t n_type_ids = flatbuffers_int32_vec_len(type_ids);

    if (n_type_ids != n_children) {
      ArrowErrorSet(
          error,
          "Expected between %ld children for Union type with %ld typeIds but found %ld",
          (long)n_type_ids, (long)n_type_ids, (long)n_children);
      return EINVAL;
    }

    if (n_type_ids > 0) {
      n_chars = snprintf(format_cursor, format_out_size, "%d",
                         flatbuffers_int32_vec_at(type_ids, 0));
      format_cursor += n_chars;
      format_out_size -= n_chars;

      for (int64_t i = 1; i < n_type_ids; i++) {
        n_chars = snprintf(format_cursor, format_out_size, ",%d",
                           (int)flatbuffers_int32_vec_at(type_ids, i));
        format_cursor += n_chars;
        format_out_size -= n_chars;
      }
    }
  } else if (n_children > 0) {
    n_chars = snprintf(format_cursor, format_out_size, "0");
    format_cursor += n_chars;
    format_out_size -= n_chars;

    for (int64_t i = 1; i < n_children; i++) {
      n_chars = snprintf(format_cursor, format_out_size, ",%d", (int)i);
      format_cursor += n_chars;
      format_out_size -= n_chars;
    }
  }

  return ArrowIpcDecoderSetTypeSimpleNested(schema, union_types_str, error);
}