Function parse_header

dependencies/httplib/httplib.h:3224–3251

template <typename T>
inline bool parse_header(const char *beg, const char *end, T fn) {
  // Skip trailing spaces and tabs.
  while (beg < end && is_space_or_tab(end[-1])) {
    end--;
  }

  auto p = beg;
  while (p < end && *p != ':') {
    p++;
  }

  if (p == end) { return false; }

  auto key_end = p;

  if (*p++ != ':') { return false; }

  while (p < end && is_space_or_tab(*p)) {
    p++;
  }

  if (p < end) {
    fn(std::string(beg, key_end), decode_url(std::string(p, end), false));
    return true;
  }

  return false;
}

inline bool read_headers(Stream &strm, Headers &headers) {
  const auto bufsiz = 2048;