cpp-jwt/include/jwt/impl/string_view.ipp

#ifndef JWT_STRING_VIEW_IPP
#define JWT_STRING_VIEW_IPP

namespace jwt {

template <typename CharT, typename Traits>
auto basic_string_view<CharT, Traits>::find(
    const CharT* str, 
    size_type pos, 
    size_type n) const noexcept -> size_type
{
  assert (str);
  assert (n < (len_ - pos) && "Comparison size out of bounds");

  if (n == 0) {
    return pos <= len_ ? pos : npos;
  }
  if (n <= len_) {
    for (; pos <= (len_ - n); ++pos) {
      if (traits_type::eq(data_[pos], str[0]) &&
          traits_type::compare(data_ + pos + 1, str + 1, n - 1) == 0) {
        return pos;
      }
    }
  }

  return npos;
}

template <typename CharT, typename Traits>
auto basic_string_view<CharT, Traits>::rfind(
    const CharT* str,
    size_type pos,
    size_type n) const noexcept -> size_type
{
  assert (str);
  assert (pos < len_ && "Position out of bounds");

  if (n <= len_) {
    pos = std::min(len_ - n, pos);
    do {
      if (traits_type::eq(data_[pos], str[0]) &&
          traits_type::compare(data_ + pos + 1, str + 1, n - 1) == 0) {
        return pos;
      }
    } while (pos-- != 0);
  }

  return npos;
}

template <typename CharT, typename Traits>
auto basic_string_view<CharT, Traits>::find(
    const CharT ch, 
    size_type pos) const noexcept -> size_type
{
  if (pos < len_) {
    for (size_type i = pos; i < len_; ++i) {
      if (traits_type::eq(data_[i], ch)) return i;
    }
  }
  return npos;
}

template <typename CharT, typename Traits>
auto basic_string_view<CharT, Traits>::rfind(
    const CharT ch,
    size_type pos) const noexcept -> size_type
{
  if (pos < len_) {
    do {
      if (traits_type::eq(data_[pos], ch)) {
        return pos;
      }
    } while (pos-- != 0);
  }

  return npos;
}

template <typename CharT, typename Traits>
auto basic_string_view<CharT, Traits>::find_first_of(
    const CharT* str, 
    size_type pos, 
    size_type count) const noexcept -> size_type
{
  assert (str);

  for (size_type i = pos; i < len_; ++i) {
    auto p = traits_type::find(str, count, data_[i]);
    if (p) {
      return i;
    }
  }

  return npos;
}

template <typename CharT, typename Traits>
auto basic_string_view<CharT, Traits>::find_last_of(
    const CharT* str, 
    size_type pos, 
    size_type count) const noexcept -> size_type
{
  assert (str);
  assert (pos < len_ && "Position must be within the bounds of the view");
  size_type siz = len_;

  if (siz && count) {
    siz = std::min(pos, siz);

    do {
      auto p = traits_type::find(str, count, data_[siz]);
      if (p) {
        return siz;
      }
    } while (siz-- != 0);
  }

  return npos;
}

template <typename CharT, typename Traits>
auto basic_string_view<CharT, Traits>::find_first_not_of(
    const CharT* str,
    size_type pos,
    size_type n) const noexcept -> size_type
{
  assert (str);
  assert (pos < len_&& "Position must be within the bounds of the view");

  for (size_type i = pos; i < len_; ++i)
  {
    auto p = traits_type::find(str, n, data_[i]);
    if (not p) return i;
  }

  return npos;
}

template <typename CharT, typename Traits>
auto basic_string_view<CharT, Traits>::find_last_not_of(
    const CharT* str,
    size_type pos,
    size_type n) const noexcept -> size_type
{
  assert (str);
  assert (pos < len_ && "Position must be within the bounds of the view");

  do {
    for (size_type i = 0; i < n; ++i) {
      if (not traits_type::eq(data_[pos], str[i])) return pos;
    }
  } while (pos-- != 0);

  return npos;
}

template <typename CharT, typename Traits>
auto basic_string_view<CharT, Traits>::find_first_not_of(
    CharT ch,
    size_type pos) const noexcept -> size_type
{
  assert (pos < len_&& "Position must be within the bounds of the view");

  for (size_type i = pos; i < len_; ++i) {
    if (not traits_type::eq(data_[i], ch)) return i;
  }

  return npos;
}

template <typename CharT, typename Traits>
auto basic_string_view<CharT, Traits>::find_last_not_of(
    CharT ch,
    size_type pos) const noexcept -> size_type
{
  assert (pos < len_ && "Position must be within the bounds of the view");

  do {
    if (not traits_type::eq(data_[pos], ch)) return pos;
  } while (pos-- != 0);

  return npos;
}

// Comparison Operators

template <typename CharT, typename Traits>
bool operator== (basic_string_view<CharT, Traits> a,
                 basic_string_view<CharT, Traits> b) noexcept
{
  if (a.length() != b.length()) return false;
  using traits_type = typename basic_string_view<CharT, Traits>::traits_type;
  using size_type = typename basic_string_view<CharT, Traits>::size_type;

  for (size_type i = 0; i < a.length(); ++i) {
    if (not traits_type::eq(a[i], b[i])) return false;
  }

  return true;
}

template <typename CharT, typename Traits>
bool operator!= (basic_string_view<CharT, Traits> a,
                 basic_string_view<CharT, Traits> b) noexcept
{
  return not ( a == b );
}

template <typename CharT, typename Traits>
bool operator< (basic_string_view<CharT, Traits> a,
                basic_string_view<CharT, Traits> b) noexcept
{
  return a.compare(b) < 0;
}

template <typename CharT, typename Traits>
bool operator> (basic_string_view<CharT, Traits> a,
                basic_string_view<CharT, Traits> b) noexcept
{
  return a.compare(b) > 0;
}

template <typename CharT, typename Traits>
bool operator<= (basic_string_view<CharT, Traits> a,
                 basic_string_view<CharT, Traits> b) noexcept
{
  return a.compare(b) <= 0;
}

template <typename CharT, typename Traits>
bool operator>= (basic_string_view<CharT, Traits> a,
                 basic_string_view<CharT, Traits> b) noexcept
{
  return a.compare(b) >= 0;
}

template <typename CharT, typename Traits>
std::ostream& operator<< (std::ostream& os, basic_string_view<CharT, Traits> sv)
{
  os.write(sv.data(), sv.length());
  return os;
}

namespace {

/*
 * Copy of gcc implementation of murmurhash
 * hash_bytes.cc
 */

inline size_t
unaligned_load(const char* p)
{
  std::size_t result;
  std::memcpy(&result, p, sizeof(result));
  return result;
}

inline size_t
hash_bytes(const void* ptr, size_t len, size_t seed)
{
  const size_t m = 0x5bd1e995;
  size_t hash = seed ^ len;
  const char* buf = static_cast<const char*>(ptr);

  // Mix 4 bytes at a time into the hash.
  while(len >= 4)
  {
    size_t k = unaligned_load(buf);
    k *= m;
    k ^= k >> 24;
    k *= m;
    hash *= m;
    hash ^= k;
    buf += 4;
    len -= 4;
  }

  // Handle the last few bytes of the input array.
  switch(len)
  {
  case 3:
    hash ^= static_cast<unsigned char>(buf[2]) << 16;
    //FALLTHROUGH 
  case 2:
    hash ^= static_cast<unsigned char>(buf[1]) << 8;
    //FALLTHROUGH
  case 1:
    hash ^= static_cast<unsigned char>(buf[0]);
    hash *= m;
  };

  // Do a few final mixes of the hash.
  hash ^= hash >> 13;
  hash *= m;
  hash ^= hash >> 15;
  return hash;
}
}

} // END namespace jwt

/// Provide a hash specialization
namespace std {
  template <>
  struct hash<jwt::string_view>
  {
    size_t operator()(const jwt::string_view& sv) const
    {
      return jwt::hash_bytes((void*)sv.data(), sv.length(), static_cast<size_t>(0xc70f6907UL));
    }
  };
}

#endif