// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___LOCALE
#define _LIBCPP___LOCALE

#include <__config>
#include <__locale_dir/locale_base_api.h>
#include <__memory/shared_ptr.h> // __shared_count
#include <__mutex/once_flag.h>
#include <__type_traits/make_unsigned.h>
#include <__utility/no_destroy.h>
#include <__utility/private_constructor_tag.h>
#include <cctype>
#include <clocale>
#include <cstdint>
#include <cstdlib>
#include <string>

// Some platforms require more includes than others. Keep the includes on all plaforms for now.
#include <cstddef>
#include <cstring>

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
#  include <cwchar>
#else
#  include <__std_mbstate_t.h>
#endif

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

class _LIBCPP_EXPORTED_FROM_ABI locale;

template <class _Facet>
_LIBCPP_HIDE_FROM_ABI bool has_facet(const locale&) _NOEXCEPT;

template <class _Facet>
_LIBCPP_HIDE_FROM_ABI const _Facet& use_facet(const locale&);

class _LIBCPP_EXPORTED_FROM_ABI locale {
public:
  // locale is essentially a shared_ptr that doesn't support weak_ptrs and never got a move constructor.
  using __trivially_relocatable = locale;

  // types:
  class _LIBCPP_EXPORTED_FROM_ABI facet;
  class _LIBCPP_EXPORTED_FROM_ABI id;

  typedef int category;

  static const category // values assigned here are for exposition only
      none    = 0,
      collate = LC_COLLATE_MASK, ctype = LC_CTYPE_MASK, monetary = LC_MONETARY_MASK, numeric = LC_NUMERIC_MASK,
      time = LC_TIME_MASK, messages = LC_MESSAGES_MASK, all = collate | ctype | monetary | numeric | time | messages;

  // construct/copy/destroy:
  locale() _NOEXCEPT;
  locale(const locale&) _NOEXCEPT;
  explicit locale(const char*);
  explicit locale(const string&);
  locale(const locale&, const char*, category);
  locale(const locale&, const string&, category);
  template <class _Facet>
  _LIBCPP_HIDE_FROM_ABI locale(const locale&, _Facet*);
  locale(const locale&, const locale&, category);

  ~locale();

  const locale& operator=(const locale&) _NOEXCEPT;

  template <class _Facet>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS locale combine(const locale&) const;

  // locale operations:
  string name() const;
  bool operator==(const locale&) const;
#if _LIBCPP_STD_VER <= 17
  _LIBCPP_HIDE_FROM_ABI bool operator!=(const locale& __y) const { return !(*this == __y); }
#endif
  template <class _CharT, class _Traits, class _Allocator>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS bool
  operator()(const basic_string<_CharT, _Traits, _Allocator>&, const basic_string<_CharT, _Traits, _Allocator>&) const;

  // global locale objects:
  static locale global(const locale&);
  static const locale& classic();

private:
  class __imp;
  __imp* __locale_;

  template <class>
  friend struct __no_destroy;
  _LIBCPP_HIDE_FROM_ABI explicit locale(__private_constructor_tag, __imp* __loc) : __locale_(__loc) {}

  void __install_ctor(const locale&, facet*, long);
  static locale& __global();
  bool has_facet(id&) const;
  const facet* use_facet(id&) const;

  template <class _Facet>
  friend bool has_facet(const locale&) _NOEXCEPT;
  template <class _Facet>
  friend const _Facet& use_facet(const locale&);
};

class _LIBCPP_EXPORTED_FROM_ABI locale::facet : public __shared_count {
protected:
  _LIBCPP_HIDE_FROM_ABI explicit facet(size_t __refs = 0) : __shared_count(static_cast<long>(__refs) - 1) {}

  ~facet() override;

  //    facet(const facet&) = delete;     // effectively done in __shared_count
  //    void operator=(const facet&) = delete;

private:
  void __on_zero_shared() _NOEXCEPT override;
};

class _LIBCPP_EXPORTED_FROM_ABI locale::id {
  once_flag __flag_;
  int32_t __id_;

  static int32_t __next_id;

public:
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR id() : __id_(0) {}
  void operator=(const id&) = delete;
  id(const id&)             = delete;

public: // only needed for tests
  long __get();

  friend class locale;
  friend class locale::__imp;
};

template <class _Facet>
inline _LIBCPP_HIDE_FROM_ABI locale::locale(const locale& __other, _Facet* __f) {
  __install_ctor(__other, __f, __f ? __f->id.__get() : 0);
}

template <class _Facet>
locale locale::combine(const locale& __other) const {
  if (!std::has_facet<_Facet>(__other))
    __throw_runtime_error("locale::combine: locale missing facet");

  return locale(*this, &const_cast<_Facet&>(std::use_facet<_Facet>(__other)));
}

template <class _Facet>
inline _LIBCPP_HIDE_FROM_ABI bool has_facet(const locale& __l) _NOEXCEPT {
  return __l.has_facet(_Facet::id);
}

template <class _Facet>
inline _LIBCPP_HIDE_FROM_ABI const _Facet& use_facet(const locale& __l) {
  return static_cast<const _Facet&>(*__l.use_facet(_Facet::id));
}

// template <class _CharT> class collate;

template <class _CharT>
class _LIBCPP_TEMPLATE_VIS collate : public locale::facet {
public:
  typedef _CharT char_type;
  typedef basic_string<char_type> string_type;

  _LIBCPP_HIDE_FROM_ABI explicit collate(size_t __refs = 0) : locale::facet(__refs) {}

  _LIBCPP_HIDE_FROM_ABI int
  compare(const char_type* __lo1, const char_type* __hi1, const char_type* __lo2, const char_type* __hi2) const {
    return do_compare(__lo1, __hi1, __lo2, __hi2);
  }

  // FIXME(EricWF): The _LIBCPP_ALWAYS_INLINE is needed on Windows to work
  // around a dllimport bug that expects an external instantiation.
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE string_type
  transform(const char_type* __lo, const char_type* __hi) const {
    return do_transform(__lo, __hi);
  }

  _LIBCPP_HIDE_FROM_ABI long hash(const char_type* __lo, const char_type* __hi) const { return do_hash(__lo, __hi); }

  static locale::id id;

protected:
  ~collate() override;
  virtual int
  do_compare(const char_type* __lo1, const char_type* __hi1, const char_type* __lo2, const char_type* __hi2) const;
  virtual string_type do_transform(const char_type* __lo, const char_type* __hi) const {
    return string_type(__lo, __hi);
  }
  virtual long do_hash(const char_type* __lo, const char_type* __hi) const;
};

template <class _CharT>
locale::id collate<_CharT>::id;

template <class _CharT>
collate<_CharT>::~collate() {}

template <class _CharT>
int collate<_CharT>::do_compare(
    const char_type* __lo1, const char_type* __hi1, const char_type* __lo2, const char_type* __hi2) const {
  for (; __lo2 != __hi2; ++__lo1, ++__lo2) {
    if (__lo1 == __hi1 || *__lo1 < *__lo2)
      return -1;
    if (*__lo2 < *__lo1)
      return 1;
  }
  return __lo1 != __hi1;
}

template <class _CharT>
long collate<_CharT>::do_hash(const char_type* __lo, const char_type* __hi) const {
  size_t __h          = 0;
  const size_t __sr   = __CHAR_BIT__ * sizeof(size_t) - 8;
  const size_t __mask = size_t(0xF) << (__sr + 4);
  for (const char_type* __p = __lo; __p != __hi; ++__p) {
    __h        = (__h << 4) + static_cast<size_t>(*__p);
    size_t __g = __h & __mask;
    __h ^= __g | (__g >> __sr);
  }
  return static_cast<long>(__h);
}

extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS collate<char>;
#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS collate<wchar_t>;
#endif

// template <class CharT> class collate_byname;

template <class _CharT>
class _LIBCPP_TEMPLATE_VIS collate_byname;

template <>
class _LIBCPP_EXPORTED_FROM_ABI collate_byname<char> : public collate<char> {
  locale_t __l_;

public:
  typedef char char_type;
  typedef basic_string<char_type> string_type;

  explicit collate_byname(const char* __n, size_t __refs = 0);
  explicit collate_byname(const string& __n, size_t __refs = 0);

protected:
  ~collate_byname() override;
  int do_compare(
      const char_type* __lo1, const char_type* __hi1, const char_type* __lo2, const char_type* __hi2) const override;
  string_type do_transform(const char_type* __lo, const char_type* __hi) const override;
};

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <>
class _LIBCPP_EXPORTED_FROM_ABI collate_byname<wchar_t> : public collate<wchar_t> {
  locale_t __l_;

public:
  typedef wchar_t char_type;
  typedef basic_string<char_type> string_type;

  explicit collate_byname(const char* __n, size_t __refs = 0);
  explicit collate_byname(const string& __n, size_t __refs = 0);

protected:
  ~collate_byname() override;

  int do_compare(
      const char_type* __lo1, const char_type* __hi1, const char_type* __lo2, const char_type* __hi2) const override;
  string_type do_transform(const char_type* __lo, const char_type* __hi) const override;
};
#endif

template <class _CharT, class _Traits, class _Allocator>
bool locale::operator()(const basic_string<_CharT, _Traits, _Allocator>& __x,
                        const basic_string<_CharT, _Traits, _Allocator>& __y) const {
  return std::use_facet<std::collate<_CharT> >(*this).compare(
             __x.data(), __x.data() + __x.size(), __y.data(), __y.data() + __y.size()) < 0;
}

// template <class charT> class ctype

class _LIBCPP_EXPORTED_FROM_ABI ctype_base {
public:
#if defined(_LIBCPP_PROVIDES_DEFAULT_RUNE_TABLE)
  typedef unsigned long mask;
  static const mask space  = 1 << 0;
  static const mask print  = 1 << 1;
  static const mask cntrl  = 1 << 2;
  static const mask upper  = 1 << 3;
  static const mask lower  = 1 << 4;
  static const mask alpha  = 1 << 5;
  static const mask digit  = 1 << 6;
  static const mask punct  = 1 << 7;
  static const mask xdigit = 1 << 8;
  static const mask blank  = 1 << 9;
#  if defined(__BIONIC__)
  // Historically this was a part of regex_traits rather than ctype_base. The
  // historical value of the constant is preserved for ABI compatibility.
  static const mask __regex_word = 0x8000;
#  else
  static const mask __regex_word = 1 << 10;
#  endif // defined(__BIONIC__)
#elif defined(__GLIBC__)
  typedef unsigned short mask;
  static const mask space  = _ISspace;
  static const mask print  = _ISprint;
  static const mask cntrl  = _IScntrl;
  static const mask upper  = _ISupper;
  static const mask lower  = _ISlower;
  static const mask alpha  = _ISalpha;
  static const mask digit  = _ISdigit;
  static const mask punct  = _ISpunct;
  static const mask xdigit = _ISxdigit;
  static const mask blank  = _ISblank;
#  if defined(__mips__) || (BYTE_ORDER == BIG_ENDIAN)
  static const mask __regex_word = static_cast<mask>(_ISbit(15));
#  else
  static const mask __regex_word = 0x80;
#  endif
#elif defined(_LIBCPP_MSVCRT_LIKE)
  typedef unsigned short mask;
  static const mask space        = _SPACE;
  static const mask print        = _BLANK | _PUNCT | _ALPHA | _DIGIT;
  static const mask cntrl        = _CONTROL;
  static const mask upper        = _UPPER;
  static const mask lower        = _LOWER;
  static const mask alpha        = _ALPHA;
  static const mask digit        = _DIGIT;
  static const mask punct        = _PUNCT;
  static const mask xdigit       = _HEX;
  static const mask blank        = _BLANK;
  static const mask __regex_word = 0x4000; // 0x8000 and 0x0100 and 0x00ff are used
#  define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_PRINT
#  define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_ALPHA
#elif defined(__APPLE__) || defined(__FreeBSD__) || defined(__NetBSD__)
#  ifdef __APPLE__
  typedef __uint32_t mask;
#  elif defined(__FreeBSD__)
  typedef unsigned long mask;
#  elif defined(__NetBSD__)
  typedef unsigned short mask;
#  endif
  static const mask space  = _CTYPE_S;
  static const mask print  = _CTYPE_R;
  static const mask cntrl  = _CTYPE_C;
  static const mask upper  = _CTYPE_U;
  static const mask lower  = _CTYPE_L;
  static const mask alpha  = _CTYPE_A;
  static const mask digit  = _CTYPE_D;
  static const mask punct  = _CTYPE_P;
  static const mask xdigit = _CTYPE_X;

#  if defined(__NetBSD__)
  static const mask blank = _CTYPE_BL;
  // NetBSD defines classes up to 0x2000
  // see sys/ctype_bits.h, _CTYPE_Q
  static const mask __regex_word = 0x8000;
#  else
  static const mask blank        = _CTYPE_B;
  static const mask __regex_word = 0x80;
#  endif
#elif defined(_AIX)
  typedef unsigned int mask;
  static const mask space        = _ISSPACE;
  static const mask print        = _ISPRINT;
  static const mask cntrl        = _ISCNTRL;
  static const mask upper        = _ISUPPER;
  static const mask lower        = _ISLOWER;
  static const mask alpha        = _ISALPHA;
  static const mask digit        = _ISDIGIT;
  static const mask punct        = _ISPUNCT;
  static const mask xdigit       = _ISXDIGIT;
  static const mask blank        = _ISBLANK;
  static const mask __regex_word = 0x8000;
#elif defined(_NEWLIB_VERSION)
  // Same type as Newlib's _ctype_ array in newlib/libc/include/ctype.h.
  typedef char mask;
  // In case char is signed, static_cast is needed to avoid warning on
  // positive value becomming negative.
  static const mask space  = static_cast<mask>(_S);
  static const mask print  = static_cast<mask>(_P | _U | _L | _N | _B);
  static const mask cntrl  = static_cast<mask>(_C);
  static const mask upper  = static_cast<mask>(_U);
  static const mask lower  = static_cast<mask>(_L);
  static const mask alpha  = static_cast<mask>(_U | _L);
  static const mask digit  = static_cast<mask>(_N);
  static const mask punct  = static_cast<mask>(_P);
  static const mask xdigit = static_cast<mask>(_X | _N);
  static const mask blank  = static_cast<mask>(_B);
  // mask is already fully saturated, use a different type in regex_type_traits.
  static const unsigned short __regex_word = 0x100;
#  define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_PRINT
#  define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_ALPHA
#  define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_XDIGIT
#elif defined(__MVS__)
#  if defined(__NATIVE_ASCII_F)
  typedef unsigned int mask;
  static const mask space  = _ISSPACE_A;
  static const mask print  = _ISPRINT_A;
  static const mask cntrl  = _ISCNTRL_A;
  static const mask upper  = _ISUPPER_A;
  static const mask lower  = _ISLOWER_A;
  static const mask alpha  = _ISALPHA_A;
  static const mask digit  = _ISDIGIT_A;
  static const mask punct  = _ISPUNCT_A;
  static const mask xdigit = _ISXDIGIT_A;
  static const mask blank  = _ISBLANK_A;
#  else
  typedef unsigned short mask;
  static const mask space  = __ISSPACE;
  static const mask print  = __ISPRINT;
  static const mask cntrl  = __ISCNTRL;
  static const mask upper  = __ISUPPER;
  static const mask lower  = __ISLOWER;
  static const mask alpha  = __ISALPHA;
  static const mask digit  = __ISDIGIT;
  static const mask punct  = __ISPUNCT;
  static const mask xdigit = __ISXDIGIT;
  static const mask blank  = __ISBLANK;
#  endif
  static const mask __regex_word = 0x8000;
#else
#  error unknown rune table for this platform -- do you mean to define _LIBCPP_PROVIDES_DEFAULT_RUNE_TABLE?
#endif
  static const mask alnum = alpha | digit;
  static const mask graph = alnum | punct;

  _LIBCPP_HIDE_FROM_ABI ctype_base() {}

  static_assert((__regex_word & ~(std::make_unsigned<mask>::type)(space | print | cntrl | upper | lower | alpha |
                                                                  digit | punct | xdigit | blank)) == __regex_word,
                "__regex_word can't overlap other bits");
};

template <class _CharT>
class _LIBCPP_TEMPLATE_VIS ctype;

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <>
class _LIBCPP_EXPORTED_FROM_ABI ctype<wchar_t> : public locale::facet, public ctype_base {
public:
  typedef wchar_t char_type;

  _LIBCPP_HIDE_FROM_ABI explicit ctype(size_t __refs = 0) : locale::facet(__refs) {}

  _LIBCPP_HIDE_FROM_ABI bool is(mask __m, char_type __c) const { return do_is(__m, __c); }

  _LIBCPP_HIDE_FROM_ABI const char_type* is(const char_type* __low, const char_type* __high, mask* __vec) const {
    return do_is(__low, __high, __vec);
  }

  _LIBCPP_HIDE_FROM_ABI const char_type* scan_is(mask __m, const char_type* __low, const char_type* __high) const {
    return do_scan_is(__m, __low, __high);
  }

  _LIBCPP_HIDE_FROM_ABI const char_type* scan_not(mask __m, const char_type* __low, const char_type* __high) const {
    return do_scan_not(__m, __low, __high);
  }

  _LIBCPP_HIDE_FROM_ABI char_type toupper(char_type __c) const { return do_toupper(__c); }

  _LIBCPP_HIDE_FROM_ABI const char_type* toupper(char_type* __low, const char_type* __high) const {
    return do_toupper(__low, __high);
  }

  _LIBCPP_HIDE_FROM_ABI char_type tolower(char_type __c) const { return do_tolower(__c); }

  _LIBCPP_HIDE_FROM_ABI const char_type* tolower(char_type* __low, const char_type* __high) const {
    return do_tolower(__low, __high);
  }

  _LIBCPP_HIDE_FROM_ABI char_type widen(char __c) const { return do_widen(__c); }

  _LIBCPP_HIDE_FROM_ABI const char* widen(const char* __low, const char* __high, char_type* __to) const {
    return do_widen(__low, __high, __to);
  }

  _LIBCPP_HIDE_FROM_ABI char narrow(char_type __c, char __dfault) const { return do_narrow(__c, __dfault); }

  _LIBCPP_HIDE_FROM_ABI const char_type*
  narrow(const char_type* __low, const char_type* __high, char __dfault, char* __to) const {
    return do_narrow(__low, __high, __dfault, __to);
  }

  static locale::id id;

protected:
  ~ctype() override;
  virtual bool do_is(mask __m, char_type __c) const;
  virtual const char_type* do_is(const char_type* __low, const char_type* __high, mask* __vec) const;
  virtual const char_type* do_scan_is(mask __m, const char_type* __low, const char_type* __high) const;
  virtual const char_type* do_scan_not(mask __m, const char_type* __low, const char_type* __high) const;
  virtual char_type do_toupper(char_type) const;
  virtual const char_type* do_toupper(char_type* __low, const char_type* __high) const;
  virtual char_type do_tolower(char_type) const;
  virtual const char_type* do_tolower(char_type* __low, const char_type* __high) const;
  virtual char_type do_widen(char) const;
  virtual const char* do_widen(const char* __low, const char* __high, char_type* __dest) const;
  virtual char do_narrow(char_type, char __dfault) const;
  virtual const char_type*
  do_narrow(const char_type* __low, const char_type* __high, char __dfault, char* __dest) const;
};
#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS

template <>
class _LIBCPP_EXPORTED_FROM_ABI ctype<char> : public locale::facet, public ctype_base {
  const mask* __tab_;
  bool __del_;

public:
  typedef char char_type;

  explicit ctype(const mask* __tab = nullptr, bool __del = false, size_t __refs = 0);

  _LIBCPP_HIDE_FROM_ABI bool is(mask __m, char_type __c) const {
    return isascii(__c) ? (__tab_[static_cast<int>(__c)] & __m) != 0 : false;
  }

  _LIBCPP_HIDE_FROM_ABI const char_type* is(const char_type* __low, const char_type* __high, mask* __vec) const {
    for (; __low != __high; ++__low, ++__vec)
      *__vec = isascii(*__low) ? __tab_[static_cast<int>(*__low)] : 0;
    return __low;
  }

  _LIBCPP_HIDE_FROM_ABI const char_type* scan_is(mask __m, const char_type* __low, const char_type* __high) const {
    for (; __low != __high; ++__low)
      if (isascii(*__low) && (__tab_[static_cast<int>(*__low)] & __m))
        break;
    return __low;
  }

  _LIBCPP_HIDE_FROM_ABI const char_type* scan_not(mask __m, const char_type* __low, const char_type* __high) const {
    for (; __low != __high; ++__low)
      if (!isascii(*__low) || !(__tab_[static_cast<int>(*__low)] & __m))
        break;
    return __low;
  }

  _LIBCPP_HIDE_FROM_ABI char_type toupper(char_type __c) const { return do_toupper(__c); }

  _LIBCPP_HIDE_FROM_ABI const char_type* toupper(char_type* __low, const char_type* __high) const {
    return do_toupper(__low, __high);
  }

  _LIBCPP_HIDE_FROM_ABI char_type tolower(char_type __c) const { return do_tolower(__c); }

  _LIBCPP_HIDE_FROM_ABI const char_type* tolower(char_type* __low, const char_type* __high) const {
    return do_tolower(__low, __high);
  }

  _LIBCPP_HIDE_FROM_ABI char_type widen(char __c) const { return do_widen(__c); }

  _LIBCPP_HIDE_FROM_ABI const char* widen(const char* __low, const char* __high, char_type* __to) const {
    return do_widen(__low, __high, __to);
  }

  _LIBCPP_HIDE_FROM_ABI char narrow(char_type __c, char __dfault) const { return do_narrow(__c, __dfault); }

  _LIBCPP_HIDE_FROM_ABI const char*
  narrow(const char_type* __low, const char_type* __high, char __dfault, char* __to) const {
    return do_narrow(__low, __high, __dfault, __to);
  }

  static locale::id id;

#ifdef _CACHED_RUNES
  static const size_t table_size = _CACHED_RUNES;
#else
  static const size_t table_size = 256; // FIXME: Don't hardcode this.
#endif
  _LIBCPP_HIDE_FROM_ABI const mask* table() const _NOEXCEPT { return __tab_; }
  static const mask* classic_table() _NOEXCEPT;
#if defined(__GLIBC__) || defined(__EMSCRIPTEN__)
  static const int* __classic_upper_table() _NOEXCEPT;
  static const int* __classic_lower_table() _NOEXCEPT;
#endif
#if defined(__NetBSD__)
  static const short* __classic_upper_table() _NOEXCEPT;
  static const short* __classic_lower_table() _NOEXCEPT;
#endif
#if defined(__MVS__)
  static const unsigned short* __classic_upper_table() _NOEXCEPT;
  static const unsigned short* __classic_lower_table() _NOEXCEPT;
#endif

protected:
  ~ctype() override;
  virtual char_type do_toupper(char_type __c) const;
  virtual const char_type* do_toupper(char_type* __low, const char_type* __high) const;
  virtual char_type do_tolower(char_type __c) const;
  virtual const char_type* do_tolower(char_type* __low, const char_type* __high) const;
  virtual char_type do_widen(char __c) const;
  virtual const char* do_widen(const char* __low, const char* __high, char_type* __to) const;
  virtual char do_narrow(char_type __c, char __dfault) const;
  virtual const char* do_narrow(const char_type* __low, const char_type* __high, char __dfault, char* __to) const;
};

// template <class CharT> class ctype_byname;

template <class _CharT>
class _LIBCPP_TEMPLATE_VIS ctype_byname;

template <>
class _LIBCPP_EXPORTED_FROM_ABI ctype_byname<char> : public ctype<char> {
  locale_t __l_;

public:
  explicit ctype_byname(const char*, size_t = 0);
  explicit ctype_byname(const string&, size_t = 0);

protected:
  ~ctype_byname() override;
  char_type do_toupper(char_type) const override;
  const char_type* do_toupper(char_type* __low, const char_type* __high) const override;
  char_type do_tolower(char_type) const override;
  const char_type* do_tolower(char_type* __low, const char_type* __high) const override;
};

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <>
class _LIBCPP_EXPORTED_FROM_ABI ctype_byname<wchar_t> : public ctype<wchar_t> {
  locale_t __l_;

public:
  explicit ctype_byname(const char*, size_t = 0);
  explicit ctype_byname(const string&, size_t = 0);

protected:
  ~ctype_byname() override;
  bool do_is(mask __m, char_type __c) const override;
  const char_type* do_is(const char_type* __low, const char_type* __high, mask* __vec) const override;
  const char_type* do_scan_is(mask __m, const char_type* __low, const char_type* __high) const override;
  const char_type* do_scan_not(mask __m, const char_type* __low, const char_type* __high) const override;
  char_type do_toupper(char_type) const override;
  const char_type* do_toupper(char_type* __low, const char_type* __high) const override;
  char_type do_tolower(char_type) const override;
  const char_type* do_tolower(char_type* __low, const char_type* __high) const override;
  char_type do_widen(char) const override;
  const char* do_widen(const char* __low, const char* __high, char_type* __dest) const override;
  char do_narrow(char_type, char __dfault) const override;
  const char_type*
  do_narrow(const char_type* __low, const char_type* __high, char __dfault, char* __dest) const override;
};
#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS

template <class _CharT>
inline _LIBCPP_HIDE_FROM_ABI bool isspace(_CharT __c, const locale& __loc) {
  return std::use_facet<ctype<_CharT> >(__loc).is(ctype_base::space, __c);
}

template <class _CharT>
inline _LIBCPP_HIDE_FROM_ABI bool isprint(_CharT __c, const locale& __loc) {
  return std::use_facet<ctype<_CharT> >(__loc).is(ctype_base::print, __c);
}

template <class _CharT>
inline _LIBCPP_HIDE_FROM_ABI bool iscntrl(_CharT __c, const locale& __loc) {
  return std::use_facet<ctype<_CharT> >(__loc).is(ctype_base::cntrl, __c);
}

template <class _CharT>
inline _LIBCPP_HIDE_FROM_ABI bool isupper(_CharT __c, const locale& __loc) {
  return std::use_facet<ctype<_CharT> >(__loc).is(ctype_base::upper, __c);
}

template <class _CharT>
inline _LIBCPP_HIDE_FROM_ABI bool islower(_CharT __c, const locale& __loc) {
  return std::use_facet<ctype<_CharT> >(__loc).is(ctype_base::lower, __c);
}

template <class _CharT>
inline _LIBCPP_HIDE_FROM_ABI bool isalpha(_CharT __c, const locale& __loc) {
  return std::use_facet<ctype<_CharT> >(__loc).is(ctype_base::alpha, __c);
}

template <class _CharT>
inline _LIBCPP_HIDE_FROM_ABI bool isdigit(_CharT __c, const locale& __loc) {
  return std::use_facet<ctype<_CharT> >(__loc).is(ctype_base::digit, __c);
}

template <class _CharT>
inline _LIBCPP_HIDE_FROM_ABI bool ispunct(_CharT __c, const locale& __loc) {
  return std::use_facet<ctype<_CharT> >(__loc).is(ctype_base::punct, __c);
}

template <class _CharT>
inline _LIBCPP_HIDE_FROM_ABI bool isxdigit(_CharT __c, const locale& __loc) {
  return std::use_facet<ctype<_CharT> >(__loc).is(ctype_base::xdigit, __c);
}

template <class _CharT>
inline _LIBCPP_HIDE_FROM_ABI bool isalnum(_CharT __c, const locale& __loc) {
  return std::use_facet<ctype<_CharT> >(__loc).is(ctype_base::alnum, __c);
}

template <class _CharT>
inline _LIBCPP_HIDE_FROM_ABI bool isgraph(_CharT __c, const locale& __loc) {
  return std::use_facet<ctype<_CharT> >(__loc).is(ctype_base::graph, __c);
}

template <class _CharT>
_LIBCPP_HIDE_FROM_ABI bool isblank(_CharT __c, const locale& __loc) {
  return std::use_facet<ctype<_CharT> >(__loc).is(ctype_base::blank, __c);
}

template <class _CharT>
inline _LIBCPP_HIDE_FROM_ABI _CharT toupper(_CharT __c, const locale& __loc) {
  return std::use_facet<ctype<_CharT> >(__loc).toupper(__c);
}

template <class _CharT>
inline _LIBCPP_HIDE_FROM_ABI _CharT tolower(_CharT __c, const locale& __loc) {
  return std::use_facet<ctype<_CharT> >(__loc).tolower(__c);
}

// codecvt_base

class _LIBCPP_EXPORTED_FROM_ABI codecvt_base {
public:
  _LIBCPP_HIDE_FROM_ABI codecvt_base() {}
  enum result { ok, partial, error, noconv };
};

// template <class internT, class externT, class stateT> class codecvt;

template <class _InternT, class _ExternT, class _StateT>
class _LIBCPP_TEMPLATE_VIS codecvt;

// template <> class codecvt<char, char, mbstate_t>

template <>
class _LIBCPP_EXPORTED_FROM_ABI codecvt<char, char, mbstate_t> : public locale::facet, public codecvt_base {
public:
  typedef char intern_type;
  typedef char extern_type;
  typedef mbstate_t state_type;

  _LIBCPP_HIDE_FROM_ABI explicit codecvt(size_t __refs = 0) : locale::facet(__refs) {}

  _LIBCPP_HIDE_FROM_ABI result
  out(state_type& __st,
      const intern_type* __frm,
      const intern_type* __frm_end,
      const intern_type*& __frm_nxt,
      extern_type* __to,
      extern_type* __to_end,
      extern_type*& __to_nxt) const {
    return do_out(__st, __frm, __frm_end, __frm_nxt, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI result
  unshift(state_type& __st, extern_type* __to, extern_type* __to_end, extern_type*& __to_nxt) const {
    return do_unshift(__st, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI result
  in(state_type& __st,
     const extern_type* __frm,
     const extern_type* __frm_end,
     const extern_type*& __frm_nxt,
     intern_type* __to,
     intern_type* __to_end,
     intern_type*& __to_nxt) const {
    return do_in(__st, __frm, __frm_end, __frm_nxt, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI int encoding() const _NOEXCEPT { return do_encoding(); }

  _LIBCPP_HIDE_FROM_ABI bool always_noconv() const _NOEXCEPT { return do_always_noconv(); }

  _LIBCPP_HIDE_FROM_ABI int
  length(state_type& __st, const extern_type* __frm, const extern_type* __end, size_t __mx) const {
    return do_length(__st, __frm, __end, __mx);
  }

  _LIBCPP_HIDE_FROM_ABI int max_length() const _NOEXCEPT { return do_max_length(); }

  static locale::id id;

protected:
  _LIBCPP_HIDE_FROM_ABI explicit codecvt(const char*, size_t __refs = 0) : locale::facet(__refs) {}

  ~codecvt() override;

  virtual result
  do_out(state_type& __st,
         const intern_type* __frm,
         const intern_type* __frm_end,
         const intern_type*& __frm_nxt,
         extern_type* __to,
         extern_type* __to_end,
         extern_type*& __to_nxt) const;
  virtual result
  do_in(state_type& __st,
        const extern_type* __frm,
        const extern_type* __frm_end,
        const extern_type*& __frm_nxt,
        intern_type* __to,
        intern_type* __to_end,
        intern_type*& __to_nxt) const;
  virtual result do_unshift(state_type& __st, extern_type* __to, extern_type* __to_end, extern_type*& __to_nxt) const;
  virtual int do_encoding() const _NOEXCEPT;
  virtual bool do_always_noconv() const _NOEXCEPT;
  virtual int do_length(state_type& __st, const extern_type* __frm, const extern_type* __end, size_t __mx) const;
  virtual int do_max_length() const _NOEXCEPT;
};

// template <> class codecvt<wchar_t, char, mbstate_t>

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <>
class _LIBCPP_EXPORTED_FROM_ABI codecvt<wchar_t, char, mbstate_t> : public locale::facet, public codecvt_base {
  locale_t __l_;

public:
  typedef wchar_t intern_type;
  typedef char extern_type;
  typedef mbstate_t state_type;

  explicit codecvt(size_t __refs = 0);

  _LIBCPP_HIDE_FROM_ABI result
  out(state_type& __st,
      const intern_type* __frm,
      const intern_type* __frm_end,
      const intern_type*& __frm_nxt,
      extern_type* __to,
      extern_type* __to_end,
      extern_type*& __to_nxt) const {
    return do_out(__st, __frm, __frm_end, __frm_nxt, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI result
  unshift(state_type& __st, extern_type* __to, extern_type* __to_end, extern_type*& __to_nxt) const {
    return do_unshift(__st, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI result
  in(state_type& __st,
     const extern_type* __frm,
     const extern_type* __frm_end,
     const extern_type*& __frm_nxt,
     intern_type* __to,
     intern_type* __to_end,
     intern_type*& __to_nxt) const {
    return do_in(__st, __frm, __frm_end, __frm_nxt, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI int encoding() const _NOEXCEPT { return do_encoding(); }

  _LIBCPP_HIDE_FROM_ABI bool always_noconv() const _NOEXCEPT { return do_always_noconv(); }

  _LIBCPP_HIDE_FROM_ABI int
  length(state_type& __st, const extern_type* __frm, const extern_type* __end, size_t __mx) const {
    return do_length(__st, __frm, __end, __mx);
  }

  _LIBCPP_HIDE_FROM_ABI int max_length() const _NOEXCEPT { return do_max_length(); }

  static locale::id id;

protected:
  explicit codecvt(const char*, size_t __refs = 0);

  ~codecvt() override;

  virtual result
  do_out(state_type& __st,
         const intern_type* __frm,
         const intern_type* __frm_end,
         const intern_type*& __frm_nxt,
         extern_type* __to,
         extern_type* __to_end,
         extern_type*& __to_nxt) const;
  virtual result
  do_in(state_type& __st,
        const extern_type* __frm,
        const extern_type* __frm_end,
        const extern_type*& __frm_nxt,
        intern_type* __to,
        intern_type* __to_end,
        intern_type*& __to_nxt) const;
  virtual result do_unshift(state_type& __st, extern_type* __to, extern_type* __to_end, extern_type*& __to_nxt) const;
  virtual int do_encoding() const _NOEXCEPT;
  virtual bool do_always_noconv() const _NOEXCEPT;
  virtual int do_length(state_type&, const extern_type* __frm, const extern_type* __end, size_t __mx) const;
  virtual int do_max_length() const _NOEXCEPT;
};
#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS

// template <> class codecvt<char16_t, char, mbstate_t> // deprecated in C++20

template <>
class _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_EXPORTED_FROM_ABI codecvt<char16_t, char, mbstate_t>
    : public locale::facet, public codecvt_base {
public:
  typedef char16_t intern_type;
  typedef char extern_type;
  typedef mbstate_t state_type;

  _LIBCPP_HIDE_FROM_ABI explicit codecvt(size_t __refs = 0) : locale::facet(__refs) {}

  _LIBCPP_HIDE_FROM_ABI result
  out(state_type& __st,
      const intern_type* __frm,
      const intern_type* __frm_end,
      const intern_type*& __frm_nxt,
      extern_type* __to,
      extern_type* __to_end,
      extern_type*& __to_nxt) const {
    return do_out(__st, __frm, __frm_end, __frm_nxt, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI result
  unshift(state_type& __st, extern_type* __to, extern_type* __to_end, extern_type*& __to_nxt) const {
    return do_unshift(__st, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI result
  in(state_type& __st,
     const extern_type* __frm,
     const extern_type* __frm_end,
     const extern_type*& __frm_nxt,
     intern_type* __to,
     intern_type* __to_end,
     intern_type*& __to_nxt) const {
    return do_in(__st, __frm, __frm_end, __frm_nxt, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI int encoding() const _NOEXCEPT { return do_encoding(); }

  _LIBCPP_HIDE_FROM_ABI bool always_noconv() const _NOEXCEPT { return do_always_noconv(); }

  _LIBCPP_HIDE_FROM_ABI int
  length(state_type& __st, const extern_type* __frm, const extern_type* __end, size_t __mx) const {
    return do_length(__st, __frm, __end, __mx);
  }

  _LIBCPP_HIDE_FROM_ABI int max_length() const _NOEXCEPT { return do_max_length(); }

  static locale::id id;

protected:
  _LIBCPP_HIDE_FROM_ABI explicit codecvt(const char*, size_t __refs = 0) : locale::facet(__refs) {}

  ~codecvt() override;

  virtual result
  do_out(state_type& __st,
         const intern_type* __frm,
         const intern_type* __frm_end,
         const intern_type*& __frm_nxt,
         extern_type* __to,
         extern_type* __to_end,
         extern_type*& __to_nxt) const;
  virtual result
  do_in(state_type& __st,
        const extern_type* __frm,
        const extern_type* __frm_end,
        const extern_type*& __frm_nxt,
        intern_type* __to,
        intern_type* __to_end,
        intern_type*& __to_nxt) const;
  virtual result do_unshift(state_type& __st, extern_type* __to, extern_type* __to_end, extern_type*& __to_nxt) const;
  virtual int do_encoding() const _NOEXCEPT;
  virtual bool do_always_noconv() const _NOEXCEPT;
  virtual int do_length(state_type&, const extern_type* __frm, const extern_type* __end, size_t __mx) const;
  virtual int do_max_length() const _NOEXCEPT;
};

#ifndef _LIBCPP_HAS_NO_CHAR8_T

// template <> class codecvt<char16_t, char8_t, mbstate_t> // C++20

template <>
class _LIBCPP_EXPORTED_FROM_ABI codecvt<char16_t, char8_t, mbstate_t> : public locale::facet, public codecvt_base {
public:
  typedef char16_t intern_type;
  typedef char8_t extern_type;
  typedef mbstate_t state_type;

  _LIBCPP_HIDE_FROM_ABI explicit codecvt(size_t __refs = 0) : locale::facet(__refs) {}

  _LIBCPP_HIDE_FROM_ABI result
  out(state_type& __st,
      const intern_type* __frm,
      const intern_type* __frm_end,
      const intern_type*& __frm_nxt,
      extern_type* __to,
      extern_type* __to_end,
      extern_type*& __to_nxt) const {
    return do_out(__st, __frm, __frm_end, __frm_nxt, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI result
  unshift(state_type& __st, extern_type* __to, extern_type* __to_end, extern_type*& __to_nxt) const {
    return do_unshift(__st, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI result
  in(state_type& __st,
     const extern_type* __frm,
     const extern_type* __frm_end,
     const extern_type*& __frm_nxt,
     intern_type* __to,
     intern_type* __to_end,
     intern_type*& __to_nxt) const {
    return do_in(__st, __frm, __frm_end, __frm_nxt, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI int encoding() const _NOEXCEPT { return do_encoding(); }

  _LIBCPP_HIDE_FROM_ABI bool always_noconv() const _NOEXCEPT { return do_always_noconv(); }

  _LIBCPP_HIDE_FROM_ABI int
  length(state_type& __st, const extern_type* __frm, const extern_type* __end, size_t __mx) const {
    return do_length(__st, __frm, __end, __mx);
  }

  _LIBCPP_HIDE_FROM_ABI int max_length() const _NOEXCEPT { return do_max_length(); }

  static locale::id id;

protected:
  _LIBCPP_HIDE_FROM_ABI explicit codecvt(const char*, size_t __refs = 0) : locale::facet(__refs) {}

  ~codecvt() override;

  virtual result
  do_out(state_type& __st,
         const intern_type* __frm,
         const intern_type* __frm_end,
         const intern_type*& __frm_nxt,
         extern_type* __to,
         extern_type* __to_end,
         extern_type*& __to_nxt) const;
  virtual result
  do_in(state_type& __st,
        const extern_type* __frm,
        const extern_type* __frm_end,
        const extern_type*& __frm_nxt,
        intern_type* __to,
        intern_type* __to_end,
        intern_type*& __to_nxt) const;
  virtual result do_unshift(state_type& __st, extern_type* __to, extern_type* __to_end, extern_type*& __to_nxt) const;
  virtual int do_encoding() const _NOEXCEPT;
  virtual bool do_always_noconv() const _NOEXCEPT;
  virtual int do_length(state_type&, const extern_type* __frm, const extern_type* __end, size_t __mx) const;
  virtual int do_max_length() const _NOEXCEPT;
};

#endif

// template <> class codecvt<char32_t, char, mbstate_t> // deprecated in C++20

template <>
class _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_EXPORTED_FROM_ABI codecvt<char32_t, char, mbstate_t>
    : public locale::facet, public codecvt_base {
public:
  typedef char32_t intern_type;
  typedef char extern_type;
  typedef mbstate_t state_type;

  _LIBCPP_HIDE_FROM_ABI explicit codecvt(size_t __refs = 0) : locale::facet(__refs) {}

  _LIBCPP_HIDE_FROM_ABI result
  out(state_type& __st,
      const intern_type* __frm,
      const intern_type* __frm_end,
      const intern_type*& __frm_nxt,
      extern_type* __to,
      extern_type* __to_end,
      extern_type*& __to_nxt) const {
    return do_out(__st, __frm, __frm_end, __frm_nxt, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI result
  unshift(state_type& __st, extern_type* __to, extern_type* __to_end, extern_type*& __to_nxt) const {
    return do_unshift(__st, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI result
  in(state_type& __st,
     const extern_type* __frm,
     const extern_type* __frm_end,
     const extern_type*& __frm_nxt,
     intern_type* __to,
     intern_type* __to_end,
     intern_type*& __to_nxt) const {
    return do_in(__st, __frm, __frm_end, __frm_nxt, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI int encoding() const _NOEXCEPT { return do_encoding(); }

  _LIBCPP_HIDE_FROM_ABI bool always_noconv() const _NOEXCEPT { return do_always_noconv(); }

  _LIBCPP_HIDE_FROM_ABI int
  length(state_type& __st, const extern_type* __frm, const extern_type* __end, size_t __mx) const {
    return do_length(__st, __frm, __end, __mx);
  }

  _LIBCPP_HIDE_FROM_ABI int max_length() const _NOEXCEPT { return do_max_length(); }

  static locale::id id;

protected:
  _LIBCPP_HIDE_FROM_ABI explicit codecvt(const char*, size_t __refs = 0) : locale::facet(__refs) {}

  ~codecvt() override;

  virtual result
  do_out(state_type& __st,
         const intern_type* __frm,
         const intern_type* __frm_end,
         const intern_type*& __frm_nxt,
         extern_type* __to,
         extern_type* __to_end,
         extern_type*& __to_nxt) const;
  virtual result
  do_in(state_type& __st,
        const extern_type* __frm,
        const extern_type* __frm_end,
        const extern_type*& __frm_nxt,
        intern_type* __to,
        intern_type* __to_end,
        intern_type*& __to_nxt) const;
  virtual result do_unshift(state_type& __st, extern_type* __to, extern_type* __to_end, extern_type*& __to_nxt) const;
  virtual int do_encoding() const _NOEXCEPT;
  virtual bool do_always_noconv() const _NOEXCEPT;
  virtual int do_length(state_type&, const extern_type* __frm, const extern_type* __end, size_t __mx) const;
  virtual int do_max_length() const _NOEXCEPT;
};

#ifndef _LIBCPP_HAS_NO_CHAR8_T

// template <> class codecvt<char32_t, char8_t, mbstate_t> // C++20

template <>
class _LIBCPP_EXPORTED_FROM_ABI codecvt<char32_t, char8_t, mbstate_t> : public locale::facet, public codecvt_base {
public:
  typedef char32_t intern_type;
  typedef char8_t extern_type;
  typedef mbstate_t state_type;

  _LIBCPP_HIDE_FROM_ABI explicit codecvt(size_t __refs = 0) : locale::facet(__refs) {}

  _LIBCPP_HIDE_FROM_ABI result
  out(state_type& __st,
      const intern_type* __frm,
      const intern_type* __frm_end,
      const intern_type*& __frm_nxt,
      extern_type* __to,
      extern_type* __to_end,
      extern_type*& __to_nxt) const {
    return do_out(__st, __frm, __frm_end, __frm_nxt, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI result
  unshift(state_type& __st, extern_type* __to, extern_type* __to_end, extern_type*& __to_nxt) const {
    return do_unshift(__st, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI result
  in(state_type& __st,
     const extern_type* __frm,
     const extern_type* __frm_end,
     const extern_type*& __frm_nxt,
     intern_type* __to,
     intern_type* __to_end,
     intern_type*& __to_nxt) const {
    return do_in(__st, __frm, __frm_end, __frm_nxt, __to, __to_end, __to_nxt);
  }

  _LIBCPP_HIDE_FROM_ABI int encoding() const _NOEXCEPT { return do_encoding(); }

  _LIBCPP_HIDE_FROM_ABI bool always_noconv() const _NOEXCEPT { return do_always_noconv(); }

  _LIBCPP_HIDE_FROM_ABI int
  length(state_type& __st, const extern_type* __frm, const extern_type* __end, size_t __mx) const {
    return do_length(__st, __frm, __end, __mx);
  }

  _LIBCPP_HIDE_FROM_ABI int max_length() const _NOEXCEPT { return do_max_length(); }

  static locale::id id;

protected:
  _LIBCPP_HIDE_FROM_ABI explicit codecvt(const char*, size_t __refs = 0) : locale::facet(__refs) {}

  ~codecvt() override;

  virtual result
  do_out(state_type& __st,
         const intern_type* __frm,
         const intern_type* __frm_end,
         const intern_type*& __frm_nxt,
         extern_type* __to,
         extern_type* __to_end,
         extern_type*& __to_nxt) const;
  virtual result
  do_in(state_type& __st,
        const extern_type* __frm,
        const extern_type* __frm_end,
        const extern_type*& __frm_nxt,
        intern_type* __to,
        intern_type* __to_end,
        intern_type*& __to_nxt) const;
  virtual result do_unshift(state_type& __st, extern_type* __to, extern_type* __to_end, extern_type*& __to_nxt) const;
  virtual int do_encoding() const _NOEXCEPT;
  virtual bool do_always_noconv() const _NOEXCEPT;
  virtual int do_length(state_type&, const extern_type* __frm, const extern_type* __end, size_t __mx) const;
  virtual int do_max_length() const _NOEXCEPT;
};

#endif

// template <class _InternT, class _ExternT, class _StateT> class codecvt_byname

template <class _InternT, class _ExternT, class _StateT>
class _LIBCPP_TEMPLATE_VIS codecvt_byname : public codecvt<_InternT, _ExternT, _StateT> {
public:
  _LIBCPP_HIDE_FROM_ABI explicit codecvt_byname(const char* __nm, size_t __refs = 0)
      : codecvt<_InternT, _ExternT, _StateT>(__nm, __refs) {}
  _LIBCPP_HIDE_FROM_ABI explicit codecvt_byname(const string& __nm, size_t __refs = 0)
      : codecvt<_InternT, _ExternT, _StateT>(__nm.c_str(), __refs) {}

protected:
  ~codecvt_byname() override;
};

_LIBCPP_SUPPRESS_DEPRECATED_PUSH
template <class _InternT, class _ExternT, class _StateT>
codecvt_byname<_InternT, _ExternT, _StateT>::~codecvt_byname() {}
_LIBCPP_SUPPRESS_DEPRECATED_POP

extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char, char, mbstate_t>;
#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<wchar_t, char, mbstate_t>;
#endif
extern template class _LIBCPP_DEPRECATED_IN_CXX20
_LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char16_t, char, mbstate_t>; // deprecated in C++20
extern template class _LIBCPP_DEPRECATED_IN_CXX20
_LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char32_t, char, mbstate_t>; // deprecated in C++20
#ifndef _LIBCPP_HAS_NO_CHAR8_T
extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char16_t, char8_t, mbstate_t>; // C++20
extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char32_t, char8_t, mbstate_t>; // C++20
#endif

template <size_t _Np>
struct __narrow_to_utf8 {
  template <class _OutputIterator, class _CharT>
  _OutputIterator operator()(_OutputIterator __s, const _CharT* __wb, const _CharT* __we) const;
};

template <>
struct __narrow_to_utf8<8> {
  template <class _OutputIterator, class _CharT>
  _LIBCPP_HIDE_FROM_ABI _OutputIterator operator()(_OutputIterator __s, const _CharT* __wb, const _CharT* __we) const {
    for (; __wb < __we; ++__wb, ++__s)
      *__s = *__wb;
    return __s;
  }
};

_LIBCPP_SUPPRESS_DEPRECATED_PUSH
template <>
struct _LIBCPP_EXPORTED_FROM_ABI __narrow_to_utf8<16> : public codecvt<char16_t, char, mbstate_t> {
  _LIBCPP_HIDE_FROM_ABI __narrow_to_utf8() : codecvt<char16_t, char, mbstate_t>(1) {}
  _LIBCPP_SUPPRESS_DEPRECATED_POP

  ~__narrow_to_utf8() override;

  template <class _OutputIterator, class _CharT>
  _LIBCPP_HIDE_FROM_ABI _OutputIterator operator()(_OutputIterator __s, const _CharT* __wb, const _CharT* __we) const {
    result __r = ok;
    mbstate_t __mb;
    while (__wb < __we && __r != error) {
      const int __sz = 32;
      char __buf[__sz];
      char* __bn;
      const char16_t* __wn = (const char16_t*)__wb;
      __r = do_out(__mb, (const char16_t*)__wb, (const char16_t*)__we, __wn, __buf, __buf + __sz, __bn);
      if (__r == codecvt_base::error || __wn == (const char16_t*)__wb)
        __throw_runtime_error("locale not supported");
      for (const char* __p = __buf; __p < __bn; ++__p, ++__s)
        *__s = *__p;
      __wb = (const _CharT*)__wn;
    }
    return __s;
  }
};

_LIBCPP_SUPPRESS_DEPRECATED_PUSH
template <>
struct _LIBCPP_EXPORTED_FROM_ABI __narrow_to_utf8<32> : public codecvt<char32_t, char, mbstate_t> {
  _LIBCPP_HIDE_FROM_ABI __narrow_to_utf8() : codecvt<char32_t, char, mbstate_t>(1) {}
  _LIBCPP_SUPPRESS_DEPRECATED_POP

  ~__narrow_to_utf8() override;

  template <class _OutputIterator, class _CharT>
  _LIBCPP_HIDE_FROM_ABI _OutputIterator operator()(_OutputIterator __s, const _CharT* __wb, const _CharT* __we) const {
    result __r = ok;
    mbstate_t __mb;
    while (__wb < __we && __r != error) {
      const int __sz = 32;
      char __buf[__sz];
      char* __bn;
      const char32_t* __wn = (const char32_t*)__wb;
      __r = do_out(__mb, (const char32_t*)__wb, (const char32_t*)__we, __wn, __buf, __buf + __sz, __bn);
      if (__r == codecvt_base::error || __wn == (const char32_t*)__wb)
        __throw_runtime_error("locale not supported");
      for (const char* __p = __buf; __p < __bn; ++__p, ++__s)
        *__s = *__p;
      __wb = (const _CharT*)__wn;
    }
    return __s;
  }
};

template <size_t _Np>
struct __widen_from_utf8 {
  template <class _OutputIterator>
  _OutputIterator operator()(_OutputIterator __s, const char* __nb, const char* __ne) const;
};

template <>
struct __widen_from_utf8<8> {
  template <class _OutputIterator>
  _LIBCPP_HIDE_FROM_ABI _OutputIterator operator()(_OutputIterator __s, const char* __nb, const char* __ne) const {
    for (; __nb < __ne; ++__nb, ++__s)
      *__s = *__nb;
    return __s;
  }
};

_LIBCPP_SUPPRESS_DEPRECATED_PUSH
template <>
struct _LIBCPP_EXPORTED_FROM_ABI __widen_from_utf8<16> : public codecvt<char16_t, char, mbstate_t> {
  _LIBCPP_HIDE_FROM_ABI __widen_from_utf8() : codecvt<char16_t, char, mbstate_t>(1) {}
  _LIBCPP_SUPPRESS_DEPRECATED_POP

  ~__widen_from_utf8() override;

  template <class _OutputIterator>
  _LIBCPP_HIDE_FROM_ABI _OutputIterator operator()(_OutputIterator __s, const char* __nb, const char* __ne) const {
    result __r = ok;
    mbstate_t __mb;
    while (__nb < __ne && __r != error) {
      const int __sz = 32;
      char16_t __buf[__sz];
      char16_t* __bn;
      const char* __nn = __nb;
      __r              = do_in(__mb, __nb, __ne - __nb > __sz ? __nb + __sz : __ne, __nn, __buf, __buf + __sz, __bn);
      if (__r == codecvt_base::error || __nn == __nb)
        __throw_runtime_error("locale not supported");
      for (const char16_t* __p = __buf; __p < __bn; ++__p, ++__s)
        *__s = *__p;
      __nb = __nn;
    }
    return __s;
  }
};

_LIBCPP_SUPPRESS_DEPRECATED_PUSH
template <>
struct _LIBCPP_EXPORTED_FROM_ABI __widen_from_utf8<32> : public codecvt<char32_t, char, mbstate_t> {
  _LIBCPP_HIDE_FROM_ABI __widen_from_utf8() : codecvt<char32_t, char, mbstate_t>(1) {}
  _LIBCPP_SUPPRESS_DEPRECATED_POP

  ~__widen_from_utf8() override;

  template <class _OutputIterator>
  _LIBCPP_HIDE_FROM_ABI _OutputIterator operator()(_OutputIterator __s, const char* __nb, const char* __ne) const {
    result __r = ok;
    mbstate_t __mb;
    while (__nb < __ne && __r != error) {
      const int __sz = 32;
      char32_t __buf[__sz];
      char32_t* __bn;
      const char* __nn = __nb;
      __r              = do_in(__mb, __nb, __ne - __nb > __sz ? __nb + __sz : __ne, __nn, __buf, __buf + __sz, __bn);
      if (__r == codecvt_base::error || __nn == __nb)
        __throw_runtime_error("locale not supported");
      for (const char32_t* __p = __buf; __p < __bn; ++__p, ++__s)
        *__s = *__p;
      __nb = __nn;
    }
    return __s;
  }
};

// template <class charT> class numpunct

template <class _CharT>
class _LIBCPP_TEMPLATE_VIS numpunct;

template <>
class _LIBCPP_EXPORTED_FROM_ABI numpunct<char> : public locale::facet {
public:
  typedef char char_type;
  typedef basic_string<char_type> string_type;

  explicit numpunct(size_t __refs = 0);

  _LIBCPP_HIDE_FROM_ABI char_type decimal_point() const { return do_decimal_point(); }
  _LIBCPP_HIDE_FROM_ABI char_type thousands_sep() const { return do_thousands_sep(); }
  _LIBCPP_HIDE_FROM_ABI string grouping() const { return do_grouping(); }
  _LIBCPP_HIDE_FROM_ABI string_type truename() const { return do_truename(); }
  _LIBCPP_HIDE_FROM_ABI string_type falsename() const { return do_falsename(); }

  static locale::id id;

protected:
  ~numpunct() override;
  virtual char_type do_decimal_point() const;
  virtual char_type do_thousands_sep() const;
  virtual string do_grouping() const;
  virtual string_type do_truename() const;
  virtual string_type do_falsename() const;

  char_type __decimal_point_;
  char_type __thousands_sep_;
  string __grouping_;
};

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <>
class _LIBCPP_EXPORTED_FROM_ABI numpunct<wchar_t> : public locale::facet {
public:
  typedef wchar_t char_type;
  typedef basic_string<char_type> string_type;

  explicit numpunct(size_t __refs = 0);

  _LIBCPP_HIDE_FROM_ABI char_type decimal_point() const { return do_decimal_point(); }
  _LIBCPP_HIDE_FROM_ABI char_type thousands_sep() const { return do_thousands_sep(); }
  _LIBCPP_HIDE_FROM_ABI string grouping() const { return do_grouping(); }
  _LIBCPP_HIDE_FROM_ABI string_type truename() const { return do_truename(); }
  _LIBCPP_HIDE_FROM_ABI string_type falsename() const { return do_falsename(); }

  static locale::id id;

protected:
  ~numpunct() override;
  virtual char_type do_decimal_point() const;
  virtual char_type do_thousands_sep() const;
  virtual string do_grouping() const;
  virtual string_type do_truename() const;
  virtual string_type do_falsename() const;

  char_type __decimal_point_;
  char_type __thousands_sep_;
  string __grouping_;
};
#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS

// template <class charT> class numpunct_byname

template <class _CharT>
class _LIBCPP_TEMPLATE_VIS numpunct_byname;

template <>
class _LIBCPP_EXPORTED_FROM_ABI numpunct_byname<char> : public numpunct<char> {
public:
  typedef char char_type;
  typedef basic_string<char_type> string_type;

  explicit numpunct_byname(const char* __nm, size_t __refs = 0);
  explicit numpunct_byname(const string& __nm, size_t __refs = 0);

protected:
  ~numpunct_byname() override;

private:
  void __init(const char*);
};

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <>
class _LIBCPP_EXPORTED_FROM_ABI numpunct_byname<wchar_t> : public numpunct<wchar_t> {
public:
  typedef wchar_t char_type;
  typedef basic_string<char_type> string_type;

  explicit numpunct_byname(const char* __nm, size_t __refs = 0);
  explicit numpunct_byname(const string& __nm, size_t __refs = 0);

protected:
  ~numpunct_byname() override;

private:
  void __init(const char*);
};
#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___LOCALE