Method parse_header

ext/src/cppformat/format.cc:687–718

template <typename Char>
unsigned fmt::internal::PrintfFormatter<Char>::parse_header(
  const Char *&s, FormatSpec &spec) {
  unsigned arg_index = UINT_MAX;
  Char c = *s;
  if (c >= '0' && c <= '9') {
    // Parse an argument index (if followed by '$') or a width possibly
    // preceded with '0' flag(s).
    unsigned value = parse_nonnegative_int(s);
    if (*s == '$') {  // value is an argument index
      ++s;
      arg_index = value;
    } else {
      if (c == '0')
        spec.fill_ = '0';
      if (value != 0) {
        // Nonzero value means that we parsed width and don't need to
        // parse it or flags again, so return now.
        spec.width_ = value;
        return arg_index;
      }
    }
  }
  parse_flags(spec, s);
  // Parse width.
  if (*s >= '0' && *s <= '9') {
    spec.width_ = parse_nonnegative_int(s);
  } else if (*s == '*') {
    ++s;
    spec.width_ = WidthHandler(spec).visit(get_arg(s));
  }
  return arg_index;
}

template <typename Char>
void fmt::internal::PrintfFormatter<Char>::format(