// -*- 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 <__availability>
#include <__config>
#include <string>
#include <memory>
#include <utility>
#include <mutex>
#include <cstdint>
#include <cctype>
#include <locale.h>
#if defined(_LIBCPP_MSVCRT_LIKE)
# include <cstring>
# include <__support/win32/locale_win32.h>
#elif defined(_AIX) || defined(__MVS__)
# include <__support/ibm/xlocale.h>
#elif defined(__ANDROID__) && !defined(BUILD_EUREKA)
# include <__support/android/locale_bionic.h>
#elif defined(__sun__)
# include <xlocale.h>
# include <__support/solaris/xlocale.h>
#elif defined(_NEWLIB_VERSION)
# include <__support/newlib/xlocale.h>
#elif defined(__OpenBSD__)
# include <__support/openbsd/xlocale.h>
#elif (defined(__APPLE__)      || defined(__FreeBSD__) \
    || defined(__EMSCRIPTEN__) || defined(__IBMCPP__))
# include <xlocale.h>
#elif defined(__Fuchsia__)
# include <__support/fuchsia/xlocale.h>
#elif defined(__wasi__)
// WASI libc uses musl's locales support.
# include <__support/musl/xlocale.h>
#elif defined(_LIBCPP_HAS_MUSL_LIBC)
# include <__support/musl/xlocale.h>
#endif

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

_LIBCPP_BEGIN_NAMESPACE_STD

#if !defined(_LIBCPP_LOCALE__L_EXTENSIONS)
struct __libcpp_locale_guard {
  _LIBCPP_INLINE_VISIBILITY
  __libcpp_locale_guard(locale_t& __loc) : __old_loc_(uselocale(__loc)) {}

  _LIBCPP_INLINE_VISIBILITY
  ~__libcpp_locale_guard() {
    if (__old_loc_)
      uselocale(__old_loc_);
  }

  locale_t __old_loc_;
private:
  __libcpp_locale_guard(__libcpp_locale_guard const&);
  __libcpp_locale_guard& operator=(__libcpp_locale_guard const&);
};
#elif defined(_LIBCPP_MSVCRT_LIKE)
struct __libcpp_locale_guard {
    __libcpp_locale_guard(locale_t __l) :
        __status(_configthreadlocale(_ENABLE_PER_THREAD_LOCALE)) {
      // Setting the locale can be expensive even when the locale given is
      // already the current locale, so do an explicit check to see if the
      // current locale is already the one we want.
      const char* __lc = __setlocale(nullptr);
      // If every category is the same, the locale string will simply be the
      // locale name, otherwise it will be a semicolon-separated string listing
      // each category.  In the second case, we know at least one category won't
      // be what we want, so we only have to check the first case.
      if (_VSTD::strcmp(__l.__get_locale(), __lc) != 0) {
        __locale_all = _strdup(__lc);
        if (__locale_all == nullptr)
          __throw_bad_alloc();
        __setlocale(__l.__get_locale());
      }
    }
    ~__libcpp_locale_guard() {
      // The CRT documentation doesn't explicitly say, but setlocale() does the
      // right thing when given a semicolon-separated list of locale settings
      // for the different categories in the same format as returned by
      // setlocale(LC_ALL, nullptr).
      if (__locale_all != nullptr) {
        __setlocale(__locale_all);
        free(__locale_all);
      }
      _configthreadlocale(__status);
    }
    static const char* __setlocale(const char* __locale) {
      const char* __new_locale = setlocale(LC_ALL, __locale);
      if (__new_locale == nullptr)
        __throw_bad_alloc();
      return __new_locale;
    }
    int __status;
    char* __locale_all = nullptr;
};
#endif

class _LIBCPP_TYPE_VIS locale;

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

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

class _LIBCPP_TYPE_VIS locale
{
public:
    // types:
    class _LIBCPP_TYPE_VIS facet;
    class _LIBCPP_TYPE_VIS id;

    typedef int category;
    _LIBCPP_AVAILABILITY_LOCALE_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_INLINE_VISIBILITY 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;
    bool operator!=(const locale& __y) const {return !(*this == __y);}
    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_;

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

    virtual ~facet();

//    facet(const facet&) = delete;     // effectively done in __shared_count
//    void operator=(const facet&) = delete;
private:
    virtual void __on_zero_shared() _NOEXCEPT;
};

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

    static int32_t __next_id;
public:
    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR id() :__id_(0) {}
private:
    void __init();
    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_INLINE_VISIBILITY
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 (!_VSTD::has_facet<_Facet>(__other))
        __throw_runtime_error("locale::combine: locale missing facet");

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

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

template <class _Facet>
inline _LIBCPP_INLINE_VISIBILITY
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_INLINE_VISIBILITY
    explicit collate(size_t __refs = 0)
        : locale::facet(__refs) {}

    _LIBCPP_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    _LIBCPP_ALWAYS_INLINE
    string_type transform(const char_type* __lo, const char_type* __hi) const
    {
        return do_transform(__lo, __hi);
    }

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

    static locale::id id;

protected:
    ~collate();
    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);
}

_LIBCPP_EXTERN_TEMPLATE_EVEN_IN_DEBUG_MODE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS collate<char>)
#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
_LIBCPP_EXTERN_TEMPLATE_EVEN_IN_DEBUG_MODE(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_TYPE_VIS 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();
    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;
};

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <>
class _LIBCPP_TYPE_VIS 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();

    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;
};
#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 _VSTD::use_facet<_VSTD::collate<_CharT> >(*this).compare(
                                       __x.data(), __x.data() + __x.size(),
                                       __y.data(), __y.data() + __y.size()) < 0;
}

// template <class charT> class ctype

class _LIBCPP_TYPE_VIS 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__)
    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 = 0x80;
# define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_PRINT
#elif defined(__APPLE__) || defined(__FreeBSD__) || defined(__EMSCRIPTEN__) || defined(__NetBSD__)
# ifdef __APPLE__
    typedef __uint32_t mask;
# elif defined(__FreeBSD__)
    typedef unsigned long mask;
# elif defined(__EMSCRIPTEN__) || 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(__sun__) || 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 = 0x80;
#elif defined(_NEWLIB_VERSION)
    // Same type as Newlib's _ctype_ array in newlib/libc/include/ctype.h.
    typedef char mask;
    static const mask space  = _S;
    static const mask print  = _P | _U | _L | _N | _B;
    static const mask cntrl  = _C;
    static const mask upper  = _U;
    static const mask lower  = _L;
    static const mask alpha  = _U | _L;
    static const mask digit  = _N;
    static const mask punct  = _P;
    static const mask xdigit = _X | _N;
    static const mask blank  = _B;
    static const mask __regex_word = 0x80;
# define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_PRINT
# define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_ALPHA
# define _LIBCPP_CTYPE_MASK_IS_COMPOSITE_XDIGIT
#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_INLINE_VISIBILITY ctype_base() {}
};

template <class _CharT> class _LIBCPP_TEMPLATE_VIS ctype;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    _LIBCPP_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    char_type toupper(char_type __c) const
    {
        return do_toupper(__c);
    }

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

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

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

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

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

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

    _LIBCPP_INLINE_VISIBILITY
    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_INLINE_VISIBILITY 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

protected:
    ~ctype();
    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_TYPE_VIS 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();
    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;
};

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <>
class _LIBCPP_TYPE_VIS 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();
    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 _CharT>
inline _LIBCPP_INLINE_VISIBILITY
bool
isspace(_CharT __c, const locale& __loc)
{
    return use_facet<ctype<_CharT> >(__loc).is(ctype_base::space, __c);
}

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

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

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

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

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

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

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

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

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

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

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

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

// codecvt_base

class _LIBCPP_TYPE_VIS codecvt_base
{
public:
    _LIBCPP_INLINE_VISIBILITY 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_TYPE_VIS 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_INLINE_VISIBILITY
    explicit codecvt(size_t __refs = 0)
        : locale::facet(__refs) {}

    _LIBCPP_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    int encoding() const  _NOEXCEPT
    {
        return do_encoding();
    }

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

    _LIBCPP_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    int max_length() const  _NOEXCEPT
    {
        return do_max_length();
    }

    static locale::id id;

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

    ~codecvt();

    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_TYPE_VIS 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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    int encoding() const  _NOEXCEPT
    {
        return do_encoding();
    }

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

    _LIBCPP_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    int max_length() const  _NOEXCEPT
    {
        return do_max_length();
    }

    static locale::id id;

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

    ~codecvt();

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

    _LIBCPP_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    int encoding() const  _NOEXCEPT
    {
        return do_encoding();
    }

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

    _LIBCPP_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    int max_length() const  _NOEXCEPT
    {
        return do_max_length();
    }

    static locale::id id;

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

    ~codecvt();

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

    _LIBCPP_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    int encoding() const  _NOEXCEPT
    {
        return do_encoding();
    }

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

    _LIBCPP_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    int max_length() const  _NOEXCEPT
    {
        return do_max_length();
    }

    static locale::id id;

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

    ~codecvt();

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

    _LIBCPP_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    int encoding() const  _NOEXCEPT
    {
        return do_encoding();
    }

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

    _LIBCPP_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    int max_length() const  _NOEXCEPT
    {
        return do_max_length();
    }

    static locale::id id;

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

    ~codecvt();

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

    _LIBCPP_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    int encoding() const  _NOEXCEPT
    {
        return do_encoding();
    }

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

    _LIBCPP_INLINE_VISIBILITY
    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_INLINE_VISIBILITY
    int max_length() const  _NOEXCEPT
    {
        return do_max_length();
    }

    static locale::id id;

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

    ~codecvt();

    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_INLINE_VISIBILITY
    explicit codecvt_byname(const char* __nm, size_t __refs = 0)
        : codecvt<_InternT, _ExternT, _StateT>(__nm, __refs) {}
    _LIBCPP_INLINE_VISIBILITY
    explicit codecvt_byname(const string& __nm, size_t __refs = 0)
        : codecvt<_InternT, _ExternT, _StateT>(__nm.c_str(), __refs) {}
protected:
    ~codecvt_byname();
};

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

_LIBCPP_EXTERN_TEMPLATE_EVEN_IN_DEBUG_MODE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char, char, mbstate_t>)
#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
_LIBCPP_EXTERN_TEMPLATE_EVEN_IN_DEBUG_MODE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<wchar_t, char, mbstate_t>)
#endif
_LIBCPP_EXTERN_TEMPLATE_EVEN_IN_DEBUG_MODE(class _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char16_t, char, mbstate_t>) // deprecated in C++20
_LIBCPP_EXTERN_TEMPLATE_EVEN_IN_DEBUG_MODE(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
_LIBCPP_EXTERN_TEMPLATE_EVEN_IN_DEBUG_MODE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS codecvt_byname<char16_t, char8_t, mbstate_t>) // C++20
_LIBCPP_EXTERN_TEMPLATE_EVEN_IN_DEBUG_MODE(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_INLINE_VISIBILITY
    _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_TYPE_VIS __narrow_to_utf8<16>
    : public codecvt<char16_t, char, mbstate_t>
{
    _LIBCPP_INLINE_VISIBILITY
    __narrow_to_utf8() : codecvt<char16_t, char, mbstate_t>(1) {}
_LIBCPP_SUPPRESS_DEPRECATED_POP

    ~__narrow_to_utf8();

    template <class _OutputIterator, class _CharT>
    _LIBCPP_INLINE_VISIBILITY
    _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_TYPE_VIS __narrow_to_utf8<32>
    : public codecvt<char32_t, char, mbstate_t>
{
    _LIBCPP_INLINE_VISIBILITY
    __narrow_to_utf8() : codecvt<char32_t, char, mbstate_t>(1) {}
_LIBCPP_SUPPRESS_DEPRECATED_POP

    ~__narrow_to_utf8();

    template <class _OutputIterator, class _CharT>
    _LIBCPP_INLINE_VISIBILITY
    _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_INLINE_VISIBILITY
    _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_TYPE_VIS __widen_from_utf8<16>
    : public codecvt<char16_t, char, mbstate_t>
{
    _LIBCPP_INLINE_VISIBILITY
    __widen_from_utf8() : codecvt<char16_t, char, mbstate_t>(1) {}
_LIBCPP_SUPPRESS_DEPRECATED_POP

    ~__widen_from_utf8();

    template <class _OutputIterator>
    _LIBCPP_INLINE_VISIBILITY
    _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_TYPE_VIS __widen_from_utf8<32>
    : public codecvt<char32_t, char, mbstate_t>
{
    _LIBCPP_INLINE_VISIBILITY
    __widen_from_utf8() : codecvt<char32_t, char, mbstate_t>(1) {}
_LIBCPP_SUPPRESS_DEPRECATED_POP

    ~__widen_from_utf8();

    template <class _OutputIterator>
    _LIBCPP_INLINE_VISIBILITY
    _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_TYPE_VIS numpunct<char>
    : public locale::facet
{
public:
    typedef char char_type;
    typedef basic_string<char_type> string_type;

    explicit numpunct(size_t __refs = 0);

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

    static locale::id id;

protected:
    ~numpunct();
    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_TYPE_VIS 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_INLINE_VISIBILITY char_type decimal_point() const {return do_decimal_point();}
    _LIBCPP_INLINE_VISIBILITY char_type thousands_sep() const {return do_thousands_sep();}
    _LIBCPP_INLINE_VISIBILITY string grouping() const         {return do_grouping();}
    _LIBCPP_INLINE_VISIBILITY string_type truename() const    {return do_truename();}
    _LIBCPP_INLINE_VISIBILITY string_type falsename() const   {return do_falsename();}

    static locale::id id;

protected:
    ~numpunct();
    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_TYPE_VIS 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();

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

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <>
class _LIBCPP_TYPE_VIS 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();

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

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___LOCALE