Method operator()

extlibs/fmt/include/fmt/format.h:2578–2590

                                       Handler&& handler) {
  struct pfs_writer {
    FMT_CONSTEXPR void operator()(const Char* begin, const Char* end) {
      if (begin == end) return;
      for (;;) {
        const Char* p = nullptr;
        if (!find<IS_CONSTEXPR>(begin, end, '}', p))
          return handler_.on_text(begin, end);
        ++p;
        if (p == end || *p != '}')
          return handler_.on_error("unmatched '}' in format string");
        handler_.on_text(begin, p);
        begin = p + 1;
      }
    }
    Handler& handler_;
  } write{handler};
  auto begin = format_str.data();