static void GetTruncatedInputStringInfo()

in sql_utils/public/error_helpers.cc [182:245]
47 lines of code
7 McCabe index (conditional complexity)

static void GetTruncatedInputStringInfo(absl::string_view input,
                                        const ErrorLocation& location,
                                        int max_width_in,
                                        std::string* truncated_input,
                                        int* error_column) {
  // We don't allow a max_width below a certain size.
  constexpr int kMinimumMaxWidth = 30;
  // If the error line is longer than max_width, give a substring of up
  // to max_width characters, with the caret near the middle of it.
  // We need some minimum width.
  const int max_width = std::max(max_width_in, kMinimumMaxWidth);

  SQL_DCHECK_GT(location.line(), 0);
  SQL_DCHECK_GT(location.column(), 0);

  ParseLocationTranslator translator(input);
  absl::StatusOr<absl::string_view> line_text =
      translator.GetLineText(location.line());
  SQL_DCHECK_OK(line_text.status());

  *truncated_input = translator.ExpandTabs(line_text.value_or(""));

  // location.column() may be one off the end of the line for EOF errors.
  SQL_DCHECK_LE(location.column(), truncated_input->size() + 1);
  // error_column is 0-based.
  *error_column =
      std::max(1, std::min(static_cast<int>(truncated_input->size() + 1),
                           location.column())) -
      1;

  if (truncated_input->size() > max_width) {
    const int one_half = max_width / 2;
    const int one_third = max_width / 3;
    // If the error is near the start, just use a prefix of the string.
    if (*error_column > max_width - one_third) {
      // Otherwise, try to find a word boundary to start the string on
      // that puts the caret in the middle third of the output line.
      int found_start = -1;
      for (int start_column = std::max(0, *error_column - 2 * one_third);
           start_column < std::max(0, *error_column - one_third);
           ++start_column) {
        if (IsWordStart(*truncated_input, start_column)) {
          found_start = start_column;
          break;
        }
      }
      if (found_start == -1) {
        // Didn't find a good separator.  Just split in the middle.
        found_start = std::max(*error_column - one_half, 0);
      }

      // Add ... prefix if necessary.
      if (found_start < 3) {
        found_start = 0;
      } else {
        *truncated_input =
            absl::StrCat("...", truncated_input->substr(found_start));
        *error_column -= found_start - 3;
      }
    }
    *truncated_input = PrettyTruncateUTF8(*truncated_input, max_width);
    SQL_DCHECK_LE(*error_column, truncated_input->size());
  }
}