Function parse

src/common/strtol.h:41–50

// Sadly GCC < 11 is missing the floating point versions.
template<typename T>
auto parse(std::string_view s, int base = 10)
  -> std::enable_if_t<std::is_integral_v<T>, std::optional<T>>
{
  T t;
  auto r = std::from_chars(s.data(), s.data() + s.size(), t, base);
  if ((r.ec != std::errc{}) || (r.ptr != s.data() + s.size())) {
    return std::nullopt;
  }
  return t;
}

// As above, but succeed on trailing characters and trim the supplied
// string_view to remove the parsed number. Set the supplied