include/__bit_reference

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___BIT_REFERENCE
#define _LIBCPP___BIT_REFERENCE

#include <__config>
#include <algorithm>

#include <__undef_min_max>

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

_LIBCPP_BEGIN_NAMESPACE_STD

template <class _Cp, bool _IsConst, typename _Cp::__storage_type = 0> class __bit_iterator;
template <class _Cp> class __bit_const_reference;

template <class _Tp>
struct __has_storage_type
{
 static const bool value = false;
};

template <class _Cp, bool = __has_storage_type<_Cp>::value>
class __bit_reference
{
 typedef typename _Cp::__storage_type __storage_type;
 typedef typename _Cp::__storage_pointer __storage_pointer;

 __storage_pointer __seg_;
 __storage_type __mask_;

#if defined(__clang__) || defined(__IBMCPP__)
 friend typename _Cp::__self;
#else
 friend class _Cp::__self;
#endif
 friend class __bit_const_reference<_Cp>;
 friend class __bit_iterator<_Cp, false>;
public:
 _LIBCPP_INLINE_VISIBILITY operator bool() const _NOEXCEPT
 {return static_cast<bool>(*__seg_ & __mask_);}
 _LIBCPP_INLINE_VISIBILITY bool operator ~() const _NOEXCEPT
 {return !static_cast<bool>(*this);}

 _LIBCPP_INLINE_VISIBILITY
 __bit_reference& operator=(bool __x) _NOEXCEPT
 {
 if (__x)
 *__seg_ |= __mask_;
 else
 *__seg_ &= ~__mask_;
 return *this;
 }

 _LIBCPP_INLINE_VISIBILITY
 __bit_reference& operator=(const __bit_reference& __x) _NOEXCEPT
 {return operator=(static_cast<bool>(__x));}

 _LIBCPP_INLINE_VISIBILITY void flip() _NOEXCEPT {*__seg_ ^= __mask_;}
 _LIBCPP_INLINE_VISIBILITY __bit_iterator<_Cp, false> operator&() const _NOEXCEPT
 {return __bit_iterator<_Cp, false>(__seg_, static_cast<unsigned>(__ctz(__mask_)));}
private:
 _LIBCPP_INLINE_VISIBILITY
 __bit_reference(__storage_pointer __s, __storage_type __m) _NOEXCEPT
 : __seg_(__s), __mask_(__m) {}
};

template <class _Cp>
class __bit_reference<_Cp, false>
{
};

template <class _Cp>
_LIBCPP_INLINE_VISIBILITY inline
void
swap(__bit_reference<_Cp> __x, __bit_reference<_Cp> __y) _NOEXCEPT
{
 bool __t = __x;
 __x = __y;
 __y = __t;
}

template <class _Cp, class _Dp>
_LIBCPP_INLINE_VISIBILITY inline
void
swap(__bit_reference<_Cp> __x, __bit_reference<_Dp> __y) _NOEXCEPT
{
 bool __t = __x;
 __x = __y;
 __y = __t;
}

template <class _Cp>
_LIBCPP_INLINE_VISIBILITY inline
void
swap(__bit_reference<_Cp> __x, bool& __y) _NOEXCEPT
{
 bool __t = __x;
 __x = __y;
 __y = __t;
}

template <class _Cp>
_LIBCPP_INLINE_VISIBILITY inline
void
swap(bool& __x, __bit_reference<_Cp> __y) _NOEXCEPT
{
 bool __t = __x;
 __x = __y;
 __y = __t;
}

template <class _Cp>
class __bit_const_reference
{
 typedef typename _Cp::__storage_type __storage_type;
 typedef typename _Cp::__const_storage_pointer __storage_pointer;

 __storage_pointer __seg_;
 __storage_type __mask_;

#if defined(__clang__) || defined(__IBMCPP__)
 friend typename _Cp::__self;
#else
 friend class _Cp::__self;
#endif
 friend class __bit_iterator<_Cp, true>;
public:
 _LIBCPP_INLINE_VISIBILITY
 __bit_const_reference(const __bit_reference<_Cp>& __x) _NOEXCEPT
 : __seg_(__x.__seg_), __mask_(__x.__mask_) {}

 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR operator bool() const _NOEXCEPT
 {return static_cast<bool>(*__seg_ & __mask_);}

 _LIBCPP_INLINE_VISIBILITY __bit_iterator<_Cp, true> operator&() const _NOEXCEPT
 {return __bit_iterator<_Cp, true>(__seg_, static_cast<unsigned>(__ctz(__mask_)));}
private:
 _LIBCPP_INLINE_VISIBILITY
 _LIBCPP_CONSTEXPR
 __bit_const_reference(__storage_pointer __s, __storage_type __m) _NOEXCEPT
 : __seg_(__s), __mask_(__m) {}

 __bit_const_reference& operator=(const __bit_const_reference& __x);
};

// find

template <class _Cp, bool _IsConst>
__bit_iterator<_Cp, _IsConst>
__find_bool_true(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
{
 typedef __bit_iterator<_Cp, _IsConst> _It;
 typedef typename _It::__storage_type __storage_type;
 static const unsigned __bits_per_word = _It::__bits_per_word;
 // do first partial word
 if (__first.__ctz_ != 0)
 {
 __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
 __storage_type __dn = _VSTD::min(__clz_f, __n);
 __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 __storage_type __b = *__first.__seg_ & __m;
 if (__b)
 return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__ctz(__b)));
 if (__n == __dn)
 return _It(__first.__seg_, __first.__ctz_ + __n);
 __n -= __dn;
 ++__first.__seg_;
 }
 // do middle whole words
 for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word)
 if (*__first.__seg_)
 return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__ctz(*__first.__seg_)));
 // do last partial word
 if (__n > 0)
 {
 __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 __storage_type __b = *__first.__seg_ & __m;
 if (__b)
 return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__ctz(__b)));
 }
 return _It(__first.__seg_, static_cast<unsigned>(__n));
}

template <class _Cp, bool _IsConst>
__bit_iterator<_Cp, _IsConst>
__find_bool_false(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
{
 typedef __bit_iterator<_Cp, _IsConst> _It;
 typedef typename _It::__storage_type __storage_type;
 static const unsigned __bits_per_word = _It::__bits_per_word;
 // do first partial word
 if (__first.__ctz_ != 0)
 {
 __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
 __storage_type __dn = _VSTD::min(__clz_f, __n);
 __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 __storage_type __b = ~*__first.__seg_ & __m;
 if (__b)
 return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__ctz(__b)));
 if (__n == __dn)
 return _It(__first.__seg_, __first.__ctz_ + __n);
 __n -= __dn;
 ++__first.__seg_;
 }
 // do middle whole words
 for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word)
 {
 __storage_type __b = ~*__first.__seg_;
 if (__b)
 return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__ctz(__b)));
 }
 // do last partial word
 if (__n > 0)
 {
 __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 __storage_type __b = ~*__first.__seg_ & __m;
 if (__b)
 return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__ctz(__b)));
 }
 return _It(__first.__seg_, static_cast<unsigned>(__n));
}

template <class _Cp, bool _IsConst, class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
__bit_iterator<_Cp, _IsConst>
find(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value_)
{
 if (static_cast<bool>(__value_))
 return __find_bool_true(__first, static_cast<typename _Cp::size_type>(__last - __first));
 return __find_bool_false(__first, static_cast<typename _Cp::size_type>(__last - __first));
}

// count

template <class _Cp, bool _IsConst>
typename __bit_iterator<_Cp, _IsConst>::difference_type
__count_bool_true(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
{
 typedef __bit_iterator<_Cp, _IsConst> _It;
 typedef typename _It::__storage_type __storage_type;
 typedef typename _It::difference_type difference_type;
 static const unsigned __bits_per_word = _It::__bits_per_word;
 difference_type __r = 0;
 // do first partial word
 if (__first.__ctz_ != 0)
 {
 __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
 __storage_type __dn = _VSTD::min(__clz_f, __n);
 __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 __r = _VSTD::__pop_count(*__first.__seg_ & __m);
 __n -= __dn;
 ++__first.__seg_;
 }
 // do middle whole words
 for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word)
 __r += _VSTD::__pop_count(*__first.__seg_);
 // do last partial word
 if (__n > 0)
 {
 __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 __r += _VSTD::__pop_count(*__first.__seg_ & __m);
 }
 return __r;
}

template <class _Cp, bool _IsConst>
typename __bit_iterator<_Cp, _IsConst>::difference_type
__count_bool_false(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
{
 typedef __bit_iterator<_Cp, _IsConst> _It;
 typedef typename _It::__storage_type __storage_type;
 typedef typename _It::difference_type difference_type;
 static const unsigned __bits_per_word = _It::__bits_per_word;
 difference_type __r = 0;
 // do first partial word
 if (__first.__ctz_ != 0)
 {
 __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
 __storage_type __dn = _VSTD::min(__clz_f, __n);
 __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 __r = _VSTD::__pop_count(~*__first.__seg_ & __m);
 __n -= __dn;
 ++__first.__seg_;
 }
 // do middle whole words
 for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word)
 __r += _VSTD::__pop_count(~*__first.__seg_);
 // do last partial word
 if (__n > 0)
 {
 __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 __r += _VSTD::__pop_count(~*__first.__seg_ & __m);
 }
 return __r;
}

template <class _Cp, bool _IsConst, class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
typename __bit_iterator<_Cp, _IsConst>::difference_type
count(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value_)
{
 if (static_cast<bool>(__value_))
 return __count_bool_true(__first, static_cast<typename _Cp::size_type>(__last - __first));
 return __count_bool_false(__first, static_cast<typename _Cp::size_type>(__last - __first));
}

// fill_n

template <class _Cp>
void
__fill_n_false(__bit_iterator<_Cp, false> __first, typename _Cp::size_type __n)
{
 typedef __bit_iterator<_Cp, false> _It;
 typedef typename _It::__storage_type __storage_type;
 static const unsigned __bits_per_word = _It::__bits_per_word;
 // do first partial word
 if (__first.__ctz_ != 0)
 {
 __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
 __storage_type __dn = _VSTD::min(__clz_f, __n);
 __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 *__first.__seg_ &= ~__m;
 __n -= __dn;
 ++__first.__seg_;
 }
 // do middle whole words
 __storage_type __nw = __n / __bits_per_word;
 _VSTD::memset(_VSTD::__to_raw_pointer(__first.__seg_), 0, __nw * sizeof(__storage_type));
 __n -= __nw * __bits_per_word;
 // do last partial word
 if (__n > 0)
 {
 __first.__seg_ += __nw;
 __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 *__first.__seg_ &= ~__m;
 }
}

template <class _Cp>
void
__fill_n_true(__bit_iterator<_Cp, false> __first, typename _Cp::size_type __n)
{
 typedef __bit_iterator<_Cp, false> _It;
 typedef typename _It::__storage_type __storage_type;
 static const unsigned __bits_per_word = _It::__bits_per_word;
 // do first partial word
 if (__first.__ctz_ != 0)
 {
 __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
 __storage_type __dn = _VSTD::min(__clz_f, __n);
 __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 *__first.__seg_ |= __m;
 __n -= __dn;
 ++__first.__seg_;
 }
 // do middle whole words
 __storage_type __nw = __n / __bits_per_word;
 _VSTD::memset(_VSTD::__to_raw_pointer(__first.__seg_), -1, __nw * sizeof(__storage_type));
 __n -= __nw * __bits_per_word;
 // do last partial word
 if (__n > 0)
 {
 __first.__seg_ += __nw;
 __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 *__first.__seg_ |= __m;
 }
}

template <class _Cp>
_LIBCPP_INLINE_VISIBILITY inline
void
fill_n(__bit_iterator<_Cp, false> __first, typename _Cp::size_type __n, bool __value_)
{
 if (__n > 0)
 {
 if (__value_)
 __fill_n_true(__first, __n);
 else
 __fill_n_false(__first, __n);
 }
}

// fill

template <class _Cp>
inline _LIBCPP_INLINE_VISIBILITY
void
fill(__bit_iterator<_Cp, false> __first, __bit_iterator<_Cp, false> __last, bool __value_)
{
 _VSTD::fill_n(__first, static_cast<typename _Cp::size_type>(__last - __first), __value_);
}

// copy

template <class _Cp, bool _IsConst>
__bit_iterator<_Cp, false>
__copy_aligned(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last,
 __bit_iterator<_Cp, false> __result)
{
 typedef __bit_iterator<_Cp, _IsConst> _In;
 typedef typename _In::difference_type difference_type;
 typedef typename _In::__storage_type __storage_type;
 static const unsigned __bits_per_word = _In::__bits_per_word;
 difference_type __n = __last - __first;
 if (__n > 0)
 {
 // do first word
 if (__first.__ctz_ != 0)
 {
 unsigned __clz = __bits_per_word - __first.__ctz_;
 difference_type __dn = _VSTD::min(static_cast<difference_type>(__clz), __n);
 __n -= __dn;
 __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz - __dn));
 __storage_type __b = *__first.__seg_ & __m;
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b;
 __result.__seg_ += (__dn + __result.__ctz_) / __bits_per_word;
 __result.__ctz_ = static_cast<unsigned>((__dn + __result.__ctz_) % __bits_per_word);
 ++__first.__seg_;
 // __first.__ctz_ = 0;
 }
 // __first.__ctz_ == 0;
 // do middle words
 __storage_type __nw = __n / __bits_per_word;
 _VSTD::memmove(_VSTD::__to_raw_pointer(__result.__seg_),
 _VSTD::__to_raw_pointer(__first.__seg_),
 __nw * sizeof(__storage_type));
 __n -= __nw * __bits_per_word;
 __result.__seg_ += __nw;
 // do last word
 if (__n > 0)
 {
 __first.__seg_ += __nw;
 __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 __storage_type __b = *__first.__seg_ & __m;
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b;
 __result.__ctz_ = static_cast<unsigned>(__n);
 }
 }
 return __result;
}

template <class _Cp, bool _IsConst>
__bit_iterator<_Cp, false>
__copy_unaligned(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last,
 __bit_iterator<_Cp, false> __result)
{
 typedef __bit_iterator<_Cp, _IsConst> _In;
 typedef typename _In::difference_type difference_type;
 typedef typename _In::__storage_type __storage_type;
 static const unsigned __bits_per_word = _In::__bits_per_word;
 difference_type __n = __last - __first;
 if (__n > 0)
 {
 // do first word
 if (__first.__ctz_ != 0)
 {
 unsigned __clz_f = __bits_per_word - __first.__ctz_;
 difference_type __dn = _VSTD::min(static_cast<difference_type>(__clz_f), __n);
 __n -= __dn;
 __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 __storage_type __b = *__first.__seg_ & __m;
 unsigned __clz_r = __bits_per_word - __result.__ctz_;
 __storage_type __ddn = _VSTD::min<__storage_type>(__dn, __clz_r);
 __m = (~__storage_type(0) << __result.__ctz_) & (~__storage_type(0) >> (__clz_r - __ddn));
 *__result.__seg_ &= ~__m;
 if (__result.__ctz_ > __first.__ctz_)
 *__result.__seg_ |= __b << (__result.__ctz_ - __first.__ctz_);
 else
 *__result.__seg_ |= __b >> (__first.__ctz_ - __result.__ctz_);
 __result.__seg_ += (__ddn + __result.__ctz_) / __bits_per_word;
 __result.__ctz_ = static_cast<unsigned>((__ddn + __result.__ctz_) % __bits_per_word);
 __dn -= __ddn;
 if (__dn > 0)
 {
 __m = ~__storage_type(0) >> (__bits_per_word - __dn);
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b >> (__first.__ctz_ + __ddn);
 __result.__ctz_ = static_cast<unsigned>(__dn);
 }
 ++__first.__seg_;
 // __first.__ctz_ = 0;
 }
 // __first.__ctz_ == 0;
 // do middle words
 unsigned __clz_r = __bits_per_word - __result.__ctz_;
 __storage_type __m = ~__storage_type(0) << __result.__ctz_;
 for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first.__seg_)
 {
 __storage_type __b = *__first.__seg_;
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b << __result.__ctz_;
 ++__result.__seg_;
 *__result.__seg_ &= __m;
 *__result.__seg_ |= __b >> __clz_r;
 }
 // do last word
 if (__n > 0)
 {
 __m = ~__storage_type(0) >> (__bits_per_word - __n);
 __storage_type __b = *__first.__seg_ & __m;
 __storage_type __dn = _VSTD::min(__n, static_cast<difference_type>(__clz_r));
 __m = (~__storage_type(0) << __result.__ctz_) & (~__storage_type(0) >> (__clz_r - __dn));
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b << __result.__ctz_;
 __result.__seg_ += (__dn + __result.__ctz_) / __bits_per_word;
 __result.__ctz_ = static_cast<unsigned>((__dn + __result.__ctz_) % __bits_per_word);
 __n -= __dn;
 if (__n > 0)
 {
 __m = ~__storage_type(0) >> (__bits_per_word - __n);
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b >> __dn;
 __result.__ctz_ = static_cast<unsigned>(__n);
 }
 }
 }
 return __result;
}

template <class _Cp, bool _IsConst>
inline _LIBCPP_INLINE_VISIBILITY
__bit_iterator<_Cp, false>
copy(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, __bit_iterator<_Cp, false> __result)
{
 if (__first.__ctz_ == __result.__ctz_)
 return __copy_aligned(__first, __last, __result);
 return __copy_unaligned(__first, __last, __result);
}

// copy_backward

template <class _Cp, bool _IsConst>
__bit_iterator<_Cp, false>
__copy_backward_aligned(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last,
 __bit_iterator<_Cp, false> __result)
{
 typedef __bit_iterator<_Cp, _IsConst> _In;
 typedef typename _In::difference_type difference_type;
 typedef typename _In::__storage_type __storage_type;
 static const unsigned __bits_per_word = _In::__bits_per_word;
 difference_type __n = __last - __first;
 if (__n > 0)
 {
 // do first word
 if (__last.__ctz_ != 0)
 {
 difference_type __dn = _VSTD::min(static_cast<difference_type>(__last.__ctz_), __n);
 __n -= __dn;
 unsigned __clz = __bits_per_word - __last.__ctz_;
 __storage_type __m = (~__storage_type(0) << (__last.__ctz_ - __dn)) & (~__storage_type(0) >> __clz);
 __storage_type __b = *__last.__seg_ & __m;
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b;
 __result.__ctz_ = static_cast<unsigned>(((-__dn & (__bits_per_word - 1)) +
 __result.__ctz_) % __bits_per_word);
 // __last.__ctz_ = 0
 }
 // __last.__ctz_ == 0 || __n == 0
 // __result.__ctz_ == 0 || __n == 0
 // do middle words
 __storage_type __nw = __n / __bits_per_word;
 __result.__seg_ -= __nw;
 __last.__seg_ -= __nw;
 _VSTD::memmove(_VSTD::__to_raw_pointer(__result.__seg_),
 _VSTD::__to_raw_pointer(__last.__seg_),
 __nw * sizeof(__storage_type));
 __n -= __nw * __bits_per_word;
 // do last word
 if (__n > 0)
 {
 __storage_type __m = ~__storage_type(0) << (__bits_per_word - __n);
 __storage_type __b = *--__last.__seg_ & __m;
 *--__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b;
 __result.__ctz_ = static_cast<unsigned>(-__n & (__bits_per_word - 1));
 }
 }
 return __result;
}

template <class _Cp, bool _IsConst>
__bit_iterator<_Cp, false>
__copy_backward_unaligned(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last,
 __bit_iterator<_Cp, false> __result)
{
 typedef __bit_iterator<_Cp, _IsConst> _In;
 typedef typename _In::difference_type difference_type;
 typedef typename _In::__storage_type __storage_type;
 static const unsigned __bits_per_word = _In::__bits_per_word;
 difference_type __n = __last - __first;
 if (__n > 0)
 {
 // do first word
 if (__last.__ctz_ != 0)
 {
 difference_type __dn = _VSTD::min(static_cast<difference_type>(__last.__ctz_), __n);
 __n -= __dn;
 unsigned __clz_l = __bits_per_word - __last.__ctz_;
 __storage_type __m = (~__storage_type(0) << (__last.__ctz_ - __dn)) & (~__storage_type(0) >> __clz_l);
 __storage_type __b = *__last.__seg_ & __m;
 unsigned __clz_r = __bits_per_word - __result.__ctz_;
 __storage_type __ddn = _VSTD::min(__dn, static_cast<difference_type>(__result.__ctz_));
 if (__ddn > 0)
 {
 __m = (~__storage_type(0) << (__result.__ctz_ - __ddn)) & (~__storage_type(0) >> __clz_r);
 *__result.__seg_ &= ~__m;
 if (__result.__ctz_ > __last.__ctz_)
 *__result.__seg_ |= __b << (__result.__ctz_ - __last.__ctz_);
 else
 *__result.__seg_ |= __b >> (__last.__ctz_ - __result.__ctz_);
 __result.__ctz_ = static_cast<unsigned>(((-__ddn & (__bits_per_word - 1)) +
 __result.__ctz_) % __bits_per_word);
 __dn -= __ddn;
 }
 if (__dn > 0)
 {
 // __result.__ctz_ == 0
 --__result.__seg_;
 __result.__ctz_ = static_cast<unsigned>(-__dn & (__bits_per_word - 1));
 __m = ~__storage_type(0) << __result.__ctz_;
 *__result.__seg_ &= ~__m;
 __last.__ctz_ -= __dn + __ddn;
 *__result.__seg_ |= __b << (__result.__ctz_ - __last.__ctz_);
 }
 // __last.__ctz_ = 0
 }
 // __last.__ctz_ == 0 || __n == 0
 // __result.__ctz_ != 0 || __n == 0
 // do middle words
 unsigned __clz_r = __bits_per_word - __result.__ctz_;
 __storage_type __m = ~__storage_type(0) >> __clz_r;
 for (; __n >= __bits_per_word; __n -= __bits_per_word)
 {
 __storage_type __b = *--__last.__seg_;
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b >> __clz_r;
 *--__result.__seg_ &= __m;
 *__result.__seg_ |= __b << __result.__ctz_;
 }
 // do last word
 if (__n > 0)
 {
 __m = ~__storage_type(0) << (__bits_per_word - __n);
 __storage_type __b = *--__last.__seg_ & __m;
 __clz_r = __bits_per_word - __result.__ctz_;
 __storage_type __dn = _VSTD::min(__n, static_cast<difference_type>(__result.__ctz_));
 __m = (~__storage_type(0) << (__result.__ctz_ - __dn)) & (~__storage_type(0) >> __clz_r);
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b >> (__bits_per_word - __result.__ctz_);
 __result.__ctz_ = static_cast<unsigned>(((-__dn & (__bits_per_word - 1)) +
 __result.__ctz_) % __bits_per_word);
 __n -= __dn;
 if (__n > 0)
 {
 // __result.__ctz_ == 0
 --__result.__seg_;
 __result.__ctz_ = static_cast<unsigned>(-__n & (__bits_per_word - 1));
 __m = ~__storage_type(0) << __result.__ctz_;
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b << (__result.__ctz_ - (__bits_per_word - __n - __dn));
 }
 }
 }
 return __result;
}

template <class _Cp, bool _IsConst>
inline _LIBCPP_INLINE_VISIBILITY
__bit_iterator<_Cp, false>
copy_backward(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, __bit_iterator<_Cp, false> __result)
{
 if (__last.__ctz_ == __result.__ctz_)
 return __copy_backward_aligned(__first, __last, __result);
 return __copy_backward_unaligned(__first, __last, __result);
}

// move

template <class _Cp, bool _IsConst>
inline _LIBCPP_INLINE_VISIBILITY
__bit_iterator<_Cp, false>
move(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, __bit_iterator<_Cp, false> __result)
{
 return _VSTD::copy(__first, __last, __result);
}

// move_backward

template <class _Cp, bool _IsConst>
inline _LIBCPP_INLINE_VISIBILITY
__bit_iterator<_Cp, false>
move_backward(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, __bit_iterator<_Cp, false> __result)
{
 return _VSTD::copy(__first, __last, __result);
}

// swap_ranges

template <class __C1, class __C2>
__bit_iterator<__C2, false>
__swap_ranges_aligned(__bit_iterator<__C1, false> __first, __bit_iterator<__C1, false> __last,
 __bit_iterator<__C2, false> __result)
{
 typedef __bit_iterator<__C1, false> _I1;
 typedef typename _I1::difference_type difference_type;
 typedef typename _I1::__storage_type __storage_type;
 static const unsigned __bits_per_word = _I1::__bits_per_word;
 difference_type __n = __last - __first;
 if (__n > 0)
 {
 // do first word
 if (__first.__ctz_ != 0)
 {
 unsigned __clz = __bits_per_word - __first.__ctz_;
 difference_type __dn = _VSTD::min(static_cast<difference_type>(__clz), __n);
 __n -= __dn;
 __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz - __dn));
 __storage_type __b1 = *__first.__seg_ & __m;
 *__first.__seg_ &= ~__m;
 __storage_type __b2 = *__result.__seg_ & __m;
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b1;
 *__first.__seg_ |= __b2;
 __result.__seg_ += (__dn + __result.__ctz_) / __bits_per_word;
 __result.__ctz_ = static_cast<unsigned>((__dn + __result.__ctz_) % __bits_per_word);
 ++__first.__seg_;
 // __first.__ctz_ = 0;
 }
 // __first.__ctz_ == 0;
 // do middle words
 for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first.__seg_, ++__result.__seg_)
 swap(*__first.__seg_, *__result.__seg_);
 // do last word
 if (__n > 0)
 {
 __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 __storage_type __b1 = *__first.__seg_ & __m;
 *__first.__seg_ &= ~__m;
 __storage_type __b2 = *__result.__seg_ & __m;
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b1;
 *__first.__seg_ |= __b2;
 __result.__ctz_ = static_cast<unsigned>(__n);
 }
 }
 return __result;
}

template <class __C1, class __C2>
__bit_iterator<__C2, false>
__swap_ranges_unaligned(__bit_iterator<__C1, false> __first, __bit_iterator<__C1, false> __last,
 __bit_iterator<__C2, false> __result)
{
 typedef __bit_iterator<__C1, false> _I1;
 typedef typename _I1::difference_type difference_type;
 typedef typename _I1::__storage_type __storage_type;
 static const unsigned __bits_per_word = _I1::__bits_per_word;
 difference_type __n = __last - __first;
 if (__n > 0)
 {
 // do first word
 if (__first.__ctz_ != 0)
 {
 unsigned __clz_f = __bits_per_word - __first.__ctz_;
 difference_type __dn = _VSTD::min(static_cast<difference_type>(__clz_f), __n);
 __n -= __dn;
 __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 __storage_type __b1 = *__first.__seg_ & __m;
 *__first.__seg_ &= ~__m;
 unsigned __clz_r = __bits_per_word - __result.__ctz_;
 __storage_type __ddn = _VSTD::min<__storage_type>(__dn, __clz_r);
 __m = (~__storage_type(0) << __result.__ctz_) & (~__storage_type(0) >> (__clz_r - __ddn));
 __storage_type __b2 = *__result.__seg_ & __m;
 *__result.__seg_ &= ~__m;
 if (__result.__ctz_ > __first.__ctz_)
 {
 unsigned __s = __result.__ctz_ - __first.__ctz_;
 *__result.__seg_ |= __b1 << __s;
 *__first.__seg_ |= __b2 >> __s;
 }
 else
 {
 unsigned __s = __first.__ctz_ - __result.__ctz_;
 *__result.__seg_ |= __b1 >> __s;
 *__first.__seg_ |= __b2 << __s;
 }
 __result.__seg_ += (__ddn + __result.__ctz_) / __bits_per_word;
 __result.__ctz_ = static_cast<unsigned>((__ddn + __result.__ctz_) % __bits_per_word);
 __dn -= __ddn;
 if (__dn > 0)
 {
 __m = ~__storage_type(0) >> (__bits_per_word - __dn);
 __b2 = *__result.__seg_ & __m;
 *__result.__seg_ &= ~__m;
 unsigned __s = __first.__ctz_ + __ddn;
 *__result.__seg_ |= __b1 >> __s;
 *__first.__seg_ |= __b2 << __s;
 __result.__ctz_ = static_cast<unsigned>(__dn);
 }
 ++__first.__seg_;
 // __first.__ctz_ = 0;
 }
 // __first.__ctz_ == 0;
 // do middle words
 __storage_type __m = ~__storage_type(0) << __result.__ctz_;
 unsigned __clz_r = __bits_per_word - __result.__ctz_;
 for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first.__seg_)
 {
 __storage_type __b1 = *__first.__seg_;
 __storage_type __b2 = *__result.__seg_ & __m;
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b1 << __result.__ctz_;
 *__first.__seg_ = __b2 >> __result.__ctz_;
 ++__result.__seg_;
 __b2 = *__result.__seg_ & ~__m;
 *__result.__seg_ &= __m;
 *__result.__seg_ |= __b1 >> __clz_r;
 *__first.__seg_ |= __b2 << __clz_r;
 }
 // do last word
 if (__n > 0)
 {
 __m = ~__storage_type(0) >> (__bits_per_word - __n);
 __storage_type __b1 = *__first.__seg_ & __m;
 *__first.__seg_ &= ~__m;
 __storage_type __dn = _VSTD::min<__storage_type>(__n, __clz_r);
 __m = (~__storage_type(0) << __result.__ctz_) & (~__storage_type(0) >> (__clz_r - __dn));
 __storage_type __b2 = *__result.__seg_ & __m;
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b1 << __result.__ctz_;
 *__first.__seg_ |= __b2 >> __result.__ctz_;
 __result.__seg_ += (__dn + __result.__ctz_) / __bits_per_word;
 __result.__ctz_ = static_cast<unsigned>((__dn + __result.__ctz_) % __bits_per_word);
 __n -= __dn;
 if (__n > 0)
 {
 __m = ~__storage_type(0) >> (__bits_per_word - __n);
 __b2 = *__result.__seg_ & __m;
 *__result.__seg_ &= ~__m;
 *__result.__seg_ |= __b1 >> __dn;
 *__first.__seg_ |= __b2 << __dn;
 __result.__ctz_ = static_cast<unsigned>(__n);
 }
 }
 }
 return __result;
}

template <class __C1, class __C2>
inline _LIBCPP_INLINE_VISIBILITY
__bit_iterator<__C2, false>
swap_ranges(__bit_iterator<__C1, false> __first1, __bit_iterator<__C1, false> __last1,
 __bit_iterator<__C2, false> __first2)
{
 if (__first1.__ctz_ == __first2.__ctz_)
 return __swap_ranges_aligned(__first1, __last1, __first2);
 return __swap_ranges_unaligned(__first1, __last1, __first2);
}

// rotate

template <class _Cp>
struct __bit_array
{
 typedef typename _Cp::difference_type difference_type;
 typedef typename _Cp::__storage_type __storage_type;
 typedef typename _Cp::__storage_pointer __storage_pointer;
 typedef typename _Cp::iterator iterator;
 static const unsigned __bits_per_word = _Cp::__bits_per_word;
 static const unsigned _Np = 4;

 difference_type __size_;
 __storage_type __word_[_Np];

 _LIBCPP_INLINE_VISIBILITY static difference_type capacity()
 {return static_cast<difference_type>(_Np * __bits_per_word);}
 _LIBCPP_INLINE_VISIBILITY explicit __bit_array(difference_type __s) : __size_(__s) {}
 _LIBCPP_INLINE_VISIBILITY iterator begin()
 {
 return iterator(pointer_traits<__storage_pointer>::pointer_to(__word_[0]), 0);
 }
 _LIBCPP_INLINE_VISIBILITY iterator end()
 {
 return iterator(pointer_traits<__storage_pointer>::pointer_to(__word_[0]) + __size_ / __bits_per_word,
 static_cast<unsigned>(__size_ % __bits_per_word));
 }
};

template <class _Cp>
__bit_iterator<_Cp, false>
rotate(__bit_iterator<_Cp, false> __first, __bit_iterator<_Cp, false> __middle, __bit_iterator<_Cp, false> __last)
{
 typedef __bit_iterator<_Cp, false> _I1;
 typedef typename _I1::difference_type difference_type;
 typedef typename _I1::__storage_type __storage_type;
 difference_type __d1 = __middle - __first;
 difference_type __d2 = __last - __middle;
 _I1 __r = __first + __d2;
 while (__d1 != 0 && __d2 != 0)
 {
 if (__d1 <= __d2)
 {
 if (__d1 <= __bit_array<_Cp>::capacity())
 {
 __bit_array<_Cp> __b(__d1);
 _VSTD::copy(__first, __middle, __b.begin());
 _VSTD::copy(__b.begin(), __b.end(), _VSTD::copy(__middle, __last, __first));
 break;
 }
 else
 {
 __bit_iterator<_Cp, false> __mp = _VSTD::swap_ranges(__first, __middle, __middle);
 __first = __middle;
 __middle = __mp;
 __d2 -= __d1;
 }
 }
 else
 {
 if (__d2 <= __bit_array<_Cp>::capacity())
 {
 __bit_array<_Cp> __b(__d2);
 _VSTD::copy(__middle, __last, __b.begin());
 _VSTD::copy_backward(__b.begin(), __b.end(), _VSTD::copy_backward(__first, __middle, __last));
 break;
 }
 else
 {
 __bit_iterator<_Cp, false> __mp = __first + __d2;
 _VSTD::swap_ranges(__first, __mp, __middle);
 __first = __mp;
 __d1 -= __d2;
 }
 }
 }
 return __r;
}

// equal

template <class _Cp, bool _IC1, bool _IC2>
bool
__equal_unaligned(__bit_iterator<_Cp, _IC1> __first1, __bit_iterator<_Cp, _IC1> __last1,
 __bit_iterator<_Cp, _IC2> __first2)
{
 typedef __bit_iterator<_Cp, _IC1> _It;
 typedef typename _It::difference_type difference_type;
 typedef typename _It::__storage_type __storage_type;
 static const unsigned __bits_per_word = _It::__bits_per_word;
 difference_type __n = __last1 - __first1;
 if (__n > 0)
 {
 // do first word
 if (__first1.__ctz_ != 0)
 {
 unsigned __clz_f = __bits_per_word - __first1.__ctz_;
 difference_type __dn = _VSTD::min(static_cast<difference_type>(__clz_f), __n);
 __n -= __dn;
 __storage_type __m = (~__storage_type(0) << __first1.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
 __storage_type __b = *__first1.__seg_ & __m;
 unsigned __clz_r = __bits_per_word - __first2.__ctz_;
 __storage_type __ddn = _VSTD::min<__storage_type>(__dn, __clz_r);
 __m = (~__storage_type(0) << __first2.__ctz_) & (~__storage_type(0) >> (__clz_r - __ddn));
 if (__first2.__ctz_ > __first1.__ctz_)
 {
 if ((*__first2.__seg_ & __m) != (__b << (__first2.__ctz_ - __first1.__ctz_)))
 return false;
 }
 else
 {
 if ((*__first2.__seg_ & __m) != (__b >> (__first1.__ctz_ - __first2.__ctz_)))
 return false;
 }
 __first2.__seg_ += (__ddn + __first2.__ctz_) / __bits_per_word;
 __first2.__ctz_ = static_cast<unsigned>((__ddn + __first2.__ctz_) % __bits_per_word);
 __dn -= __ddn;
 if (__dn > 0)
 {
 __m = ~__storage_type(0) >> (__bits_per_word - __dn);
 if ((*__first2.__seg_ & __m) != (__b >> (__first1.__ctz_ + __ddn)))
 return false;
 __first2.__ctz_ = static_cast<unsigned>(__dn);
 }
 ++__first1.__seg_;
 // __first1.__ctz_ = 0;
 }
 // __first1.__ctz_ == 0;
 // do middle words
 unsigned __clz_r = __bits_per_word - __first2.__ctz_;
 __storage_type __m = ~__storage_type(0) << __first2.__ctz_;
 for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first1.__seg_)
 {
 __storage_type __b = *__first1.__seg_;
 if ((*__first2.__seg_ & __m) != (__b << __first2.__ctz_))
 return false;
 ++__first2.__seg_;
 if ((*__first2.__seg_ & ~__m) != (__b >> __clz_r))
 return false;
 }
 // do last word
 if (__n > 0)
 {
 __m = ~__storage_type(0) >> (__bits_per_word - __n);
 __storage_type __b = *__first1.__seg_ & __m;
 __storage_type __dn = _VSTD::min(__n, static_cast<difference_type>(__clz_r));
 __m = (~__storage_type(0) << __first2.__ctz_) & (~__storage_type(0) >> (__clz_r - __dn));
 if ((*__first2.__seg_ & __m) != (__b << __first2.__ctz_))
 return false;
 __first2.__seg_ += (__dn + __first2.__ctz_) / __bits_per_word;
 __first2.__ctz_ = static_cast<unsigned>((__dn + __first2.__ctz_) % __bits_per_word);
 __n -= __dn;
 if (__n > 0)
 {
 __m = ~__storage_type(0) >> (__bits_per_word - __n);
 if ((*__first2.__seg_ & __m) != (__b >> __dn))
 return false;
 }
 }
 }
 return true;
}

template <class _Cp, bool _IC1, bool _IC2>
bool
__equal_aligned(__bit_iterator<_Cp, _IC1> __first1, __bit_iterator<_Cp, _IC1> __last1,
 __bit_iterator<_Cp, _IC2> __first2)
{
 typedef __bit_iterator<_Cp, _IC1> _It;
 typedef typename _It::difference_type difference_type;
 typedef typename _It::__storage_type __storage_type;
 static const unsigned __bits_per_word = _It::__bits_per_word;
 difference_type __n = __last1 - __first1;
 if (__n > 0)
 {
 // do first word
 if (__first1.__ctz_ != 0)
 {
 unsigned __clz = __bits_per_word - __first1.__ctz_;
 difference_type __dn = _VSTD::min(static_cast<difference_type>(__clz), __n);
 __n -= __dn;
 __storage_type __m = (~__storage_type(0) << __first1.__ctz_) & (~__storage_type(0) >> (__clz - __dn));
 if ((*__first2.__seg_ & __m) != (*__first1.__seg_ & __m))
 return false;
 ++__first2.__seg_;
 ++__first1.__seg_;
 // __first1.__ctz_ = 0;
 // __first2.__ctz_ = 0;
 }
 // __first1.__ctz_ == 0;
 // __first2.__ctz_ == 0;
 // do middle words
 for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first1.__seg_, ++__first2.__seg_)
 if (*__first2.__seg_ != *__first1.__seg_)
 return false;
 // do last word
 if (__n > 0)
 {
 __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
 if ((*__first2.__seg_ & __m) != (*__first1.__seg_ & __m))
 return false;
 }
 }
 return true;
}

template <class _Cp, bool _IC1, bool _IC2>
inline _LIBCPP_INLINE_VISIBILITY
bool
equal(__bit_iterator<_Cp, _IC1> __first1, __bit_iterator<_Cp, _IC1> __last1, __bit_iterator<_Cp, _IC2> __first2)
{
 if (__first1.__ctz_ == __first2.__ctz_)
 return __equal_aligned(__first1, __last1, __first2);
 return __equal_unaligned(__first1, __last1, __first2);
}

template <class _Cp, bool _IsConst,
 typename _Cp::__storage_type>
class __bit_iterator
{
public:
 typedef typename _Cp::difference_type difference_type;
 typedef bool value_type;
 typedef __bit_iterator pointer;
 typedef typename conditional<_IsConst, __bit_const_reference<_Cp>, __bit_reference<_Cp> >::type reference;
 typedef random_access_iterator_tag iterator_category;

private:
 typedef typename _Cp::__storage_type __storage_type;
 typedef typename conditional<_IsConst, typename _Cp::__const_storage_pointer,
 typename _Cp::__storage_pointer>::type __storage_pointer;
 static const unsigned __bits_per_word = _Cp::__bits_per_word;

 __storage_pointer __seg_;
 unsigned __ctz_;

public:
 _LIBCPP_INLINE_VISIBILITY __bit_iterator() _NOEXCEPT
#if _LIBCPP_STD_VER > 11
 : __seg_(nullptr), __ctz_(0)
#endif
 {}

 _LIBCPP_INLINE_VISIBILITY
 __bit_iterator(const __bit_iterator<_Cp, false>& __it) _NOEXCEPT
 : __seg_(__it.__seg_), __ctz_(__it.__ctz_) {}

 _LIBCPP_INLINE_VISIBILITY reference operator*() const _NOEXCEPT
 {return reference(__seg_, __storage_type(1) << __ctz_);}

 _LIBCPP_INLINE_VISIBILITY __bit_iterator& operator++()
 {
 if (__ctz_ != __bits_per_word-1)
 ++__ctz_;
 else
 {
 __ctz_ = 0;
 ++__seg_;
 }
 return *this;
 }

 _LIBCPP_INLINE_VISIBILITY __bit_iterator operator++(int)
 {
 __bit_iterator __tmp = *this;
 ++(*this);
 return __tmp;
 }

 _LIBCPP_INLINE_VISIBILITY __bit_iterator& operator--()
 {
 if (__ctz_ != 0)
 --__ctz_;
 else
 {
 __ctz_ = __bits_per_word - 1;
 --__seg_;
 }
 return *this;
 }

 _LIBCPP_INLINE_VISIBILITY __bit_iterator operator--(int)
 {
 __bit_iterator __tmp = *this;
 --(*this);
 return __tmp;
 }

 _LIBCPP_INLINE_VISIBILITY __bit_iterator& operator+=(difference_type __n)
 {
 if (__n >= 0)
 __seg_ += (__n + __ctz_) / __bits_per_word;
 else
 __seg_ += static_cast<difference_type>(__n - __bits_per_word + __ctz_ + 1)
 / static_cast<difference_type>(__bits_per_word);
 __n &= (__bits_per_word - 1);
 __ctz_ = static_cast<unsigned>((__n + __ctz_) % __bits_per_word);
 return *this;
 }

 _LIBCPP_INLINE_VISIBILITY __bit_iterator& operator-=(difference_type __n)
 {
 return *this += -__n;
 }

 _LIBCPP_INLINE_VISIBILITY __bit_iterator operator+(difference_type __n) const
 {
 __bit_iterator __t(*this);
 __t += __n;
 return __t;
 }

 _LIBCPP_INLINE_VISIBILITY __bit_iterator operator-(difference_type __n) const
 {
 __bit_iterator __t(*this);
 __t -= __n;
 return __t;
 }

 _LIBCPP_INLINE_VISIBILITY
 friend __bit_iterator operator+(difference_type __n, const __bit_iterator& __it) {return __it + __n;}

 _LIBCPP_INLINE_VISIBILITY
 friend difference_type operator-(const __bit_iterator& __x, const __bit_iterator& __y)
 {return (__x.__seg_ - __y.__seg_) * __bits_per_word + __x.__ctz_ - __y.__ctz_;}

 _LIBCPP_INLINE_VISIBILITY reference operator[](difference_type __n) const {return *(*this + __n);}

 _LIBCPP_INLINE_VISIBILITY friend bool operator==(const __bit_iterator& __x, const __bit_iterator& __y)
 {return __x.__seg_ == __y.__seg_ && __x.__ctz_ == __y.__ctz_;}

 _LIBCPP_INLINE_VISIBILITY friend bool operator!=(const __bit_iterator& __x, const __bit_iterator& __y)
 {return !(__x == __y);}

 _LIBCPP_INLINE_VISIBILITY friend bool operator<(const __bit_iterator& __x, const __bit_iterator& __y)
 {return __x.__seg_ < __y.__seg_ || (__x.__seg_ == __y.__seg_ && __x.__ctz_ < __y.__ctz_);}

 _LIBCPP_INLINE_VISIBILITY friend bool operator>(const __bit_iterator& __x, const __bit_iterator& __y)
 {return __y < __x;}

 _LIBCPP_INLINE_VISIBILITY friend bool operator<=(const __bit_iterator& __x, const __bit_iterator& __y)
 {return !(__y < __x);}

 _LIBCPP_INLINE_VISIBILITY friend bool operator>=(const __bit_iterator& __x, const __bit_iterator& __y)
 {return !(__x < __y);}

private:
 _LIBCPP_INLINE_VISIBILITY
 __bit_iterator(__storage_pointer __s, unsigned __ctz) _NOEXCEPT
 : __seg_(__s), __ctz_(__ctz) {}

#if defined(__clang__) || defined(__IBMCPP__)
 friend typename _Cp::__self;
#else
 friend class _Cp::__self;
#endif
 friend class __bit_reference<_Cp>;
 friend class __bit_const_reference<_Cp>;
 friend class __bit_iterator<_Cp, true>;
 template <class _Dp> friend struct __bit_array;
 template <class _Dp> friend void __fill_n_false(__bit_iterator<_Dp, false> __first, typename _Dp::size_type __n);
 template <class _Dp> friend void __fill_n_true(__bit_iterator<_Dp, false> __first, typename _Dp::size_type __n);
 template <class _Dp, bool _IC> friend __bit_iterator<_Dp, false> __copy_aligned(__bit_iterator<_Dp, _IC> __first,
 __bit_iterator<_Dp, _IC> __last,
 __bit_iterator<_Dp, false> __result);
 template <class _Dp, bool _IC> friend __bit_iterator<_Dp, false> __copy_unaligned(__bit_iterator<_Dp, _IC> __first,
 __bit_iterator<_Dp, _IC> __last,
 __bit_iterator<_Dp, false> __result);
 template <class _Dp, bool _IC> friend __bit_iterator<_Dp, false> copy(__bit_iterator<_Dp, _IC> __first,
 __bit_iterator<_Dp, _IC> __last,
 __bit_iterator<_Dp, false> __result);
 template <class _Dp, bool _IC> friend __bit_iterator<_Dp, false> __copy_backward_aligned(__bit_iterator<_Dp, _IC> __first,
 __bit_iterator<_Dp, _IC> __last,
 __bit_iterator<_Dp, false> __result);
 template <class _Dp, bool _IC> friend __bit_iterator<_Dp, false> __copy_backward_unaligned(__bit_iterator<_Dp, _IC> __first,
 __bit_iterator<_Dp, _IC> __last,
 __bit_iterator<_Dp, false> __result);
 template <class _Dp, bool _IC> friend __bit_iterator<_Dp, false> copy_backward(__bit_iterator<_Dp, _IC> __first,
 __bit_iterator<_Dp, _IC> __last,
 __bit_iterator<_Dp, false> __result);
 template <class __C1, class __C2>friend __bit_iterator<__C2, false> __swap_ranges_aligned(__bit_iterator<__C1, false>,
 __bit_iterator<__C1, false>,
 __bit_iterator<__C2, false>);
 template <class __C1, class __C2>friend __bit_iterator<__C2, false> __swap_ranges_unaligned(__bit_iterator<__C1, false>,
 __bit_iterator<__C1, false>,
 __bit_iterator<__C2, false>);
 template <class __C1, class __C2>friend __bit_iterator<__C2, false> swap_ranges(__bit_iterator<__C1, false>,
 __bit_iterator<__C1, false>,
 __bit_iterator<__C2, false>);
 template <class _Dp> friend __bit_iterator<_Dp, false> rotate(__bit_iterator<_Dp, false>,
 __bit_iterator<_Dp, false>,
 __bit_iterator<_Dp, false>);
 template <class _Dp, bool _IC1, bool _IC2> friend bool __equal_aligned(__bit_iterator<_Dp, _IC1>,
 __bit_iterator<_Dp, _IC1>,
 __bit_iterator<_Dp, _IC2>);
 template <class _Dp, bool _IC1, bool _IC2> friend bool __equal_unaligned(__bit_iterator<_Dp, _IC1>,
 __bit_iterator<_Dp, _IC1>,
 __bit_iterator<_Dp, _IC2>);
 template <class _Dp, bool _IC1, bool _IC2> friend bool equal(__bit_iterator<_Dp, _IC1>,
 __bit_iterator<_Dp, _IC1>,
 __bit_iterator<_Dp, _IC2>);
 template <class _Dp, bool _IC> friend __bit_iterator<_Dp, _IC> __find_bool_true(__bit_iterator<_Dp, _IC>,
 typename _Dp::size_type);
 template <class _Dp, bool _IC> friend __bit_iterator<_Dp, _IC> __find_bool_false(__bit_iterator<_Dp, _IC>,
 typename _Dp::size_type);
 template <class _Dp, bool _IC> friend typename __bit_iterator<_Dp, _IC>::difference_type
 __count_bool_true(__bit_iterator<_Dp, _IC>, typename _Dp::size_type);
 template <class _Dp, bool _IC> friend typename __bit_iterator<_Dp, _IC>::difference_type
 __count_bool_false(__bit_iterator<_Dp, _IC>, typename _Dp::size_type);
};

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___BIT_REFERENCE