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// -*- 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___BIT_REFERENCE 
#define _LIBCPP___BIT_REFERENCE 
 
#include <__config> 
#include <__bits> 
#include <algorithm> 
 
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 
#pragma GCC system_header 
#endif 
 
_LIBCPP_PUSH_MACROS 
#include <__undef_macros> 
 
 
_LIBCPP_BEGIN_NAMESPACE_STD 
 
template <class _Cp, bool _IsConst, class = typename _Cp::__storage_type> 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_; 
 
    friend typename _Cp::__self; 
 
    friend class __bit_const_reference<_Cp>; 
    friend class __bit_iterator<_Cp, false>; 
public: 
    _LIBCPP_INLINE_VISIBILITY 
    __bit_reference(const __bit_reference&) = default; 
 
    _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>(__libcpp_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> 
inline _LIBCPP_INLINE_VISIBILITY 
void 
swap(__bit_reference<_Cp> __x, __bit_reference<_Cp> __y) _NOEXCEPT 
{ 
    bool __t = __x; 
    __x = __y; 
    __y = __t; 
} 
 
template <class _Cp, class _Dp> 
inline _LIBCPP_INLINE_VISIBILITY 
void 
swap(__bit_reference<_Cp> __x, __bit_reference<_Dp> __y) _NOEXCEPT 
{ 
    bool __t = __x; 
    __x = __y; 
    __y = __t; 
} 
 
template <class _Cp> 
inline _LIBCPP_INLINE_VISIBILITY 
void 
swap(__bit_reference<_Cp> __x, bool& __y) _NOEXCEPT 
{ 
    bool __t = __x; 
    __x = __y; 
    __y = __t; 
} 
 
template <class _Cp> 
inline _LIBCPP_INLINE_VISIBILITY 
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_; 
 
    friend typename _Cp::__self; 
    friend class __bit_iterator<_Cp, true>; 
public: 
    _LIBCPP_INLINE_VISIBILITY 
    __bit_const_reference(const __bit_const_reference&) = default; 
 
    _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>(__libcpp_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&) = delete; 
}; 
 
// 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 int __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::__libcpp_ctz(__b))); 
        if (__n == __dn) 
            return __first + __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::__libcpp_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::__libcpp_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; 
    const int __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::__libcpp_ctz(__b))); 
        if (__n == __dn) 
            return __first + __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::__libcpp_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::__libcpp_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 _VSTD::__find_bool_true(__first, static_cast<typename _Cp::size_type>(__last - __first)); 
    return _VSTD::__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; 
    const int __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::__libcpp_popcount(*__first.__seg_ & __m); 
        __n -= __dn; 
        ++__first.__seg_; 
    } 
    // do middle whole words 
    for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word) 
        __r += _VSTD::__libcpp_popcount(*__first.__seg_); 
    // do last partial word 
    if (__n > 0) 
    { 
        __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n); 
        __r += _VSTD::__libcpp_popcount(*__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; 
    const int __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::__libcpp_popcount(~*__first.__seg_ & __m); 
        __n -= __dn; 
        ++__first.__seg_; 
    } 
    // do middle whole words 
    for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word) 
        __r += _VSTD::__libcpp_popcount(~*__first.__seg_); 
    // do last partial word 
    if (__n > 0) 
    { 
        __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n); 
        __r += _VSTD::__libcpp_popcount(~*__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 _VSTD::__count_bool_true(__first, static_cast<typename _Cp::size_type>(__last - __first)); 
    return _VSTD::__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; 
    const int __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_address(__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; 
    const int __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_address(__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> 
inline _LIBCPP_INLINE_VISIBILITY 
void 
fill_n(__bit_iterator<_Cp, false> __first, typename _Cp::size_type __n, bool __value_) 
{ 
    if (__n > 0) 
    { 
        if (__value_) 
            _VSTD::__fill_n_true(__first, __n); 
        else 
            _VSTD::__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; 
    const int __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_address(__result.__seg_), 
                       _VSTD::__to_address(__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 int __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 _VSTD::__copy_aligned(__first, __last, __result); 
    return _VSTD::__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; 
    const int __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_address(__result.__seg_), 
                       _VSTD::__to_address(__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; 
    const int __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 _VSTD::__copy_backward_aligned(__first, __last, __result); 
    return _VSTD::__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_backward(__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; 
    const int __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; 
    const int __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 _VSTD::__swap_ranges_aligned(__first1, __last1, __first2); 
    return _VSTD::__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; 
    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 int __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 int __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 _VSTD::__equal_aligned(__first1, __last1, __first2); 
    return _VSTD::__equal_unaligned(__first1, __last1, __first2); 
} 
 
template <class _Cp, bool _IsConst, 
          class> 
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 
    {} 
 
    // When _IsConst=false, this is the copy constructor. 
    // It is non-trivial. Making it trivial would break ABI. 
    // When _IsConst=true, this is a converting constructor; 
    // the copy and move constructors are implicitly generated 
    // and trivial. 
    _LIBCPP_INLINE_VISIBILITY 
    __bit_iterator(const __bit_iterator<_Cp, false>& __it) _NOEXCEPT 
        : __seg_(__it.__seg_), __ctz_(__it.__ctz_) {} 
 
    // When _IsConst=false, we have a user-provided copy constructor, 
    // so we must also provide a copy assignment operator because 
    // the implicit generation of a defaulted one is deprecated. 
    // When _IsConst=true, the assignment operators are 
    // implicitly generated and trivial. 
    _LIBCPP_INLINE_VISIBILITY 
    __bit_iterator& operator=(const _If<_IsConst, struct __private_nat, __bit_iterator>& __it) { 
        __seg_ = __it.__seg_; 
        __ctz_ = __it.__ctz_; 
        return *this; 
    } 
 
    _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) {} 
 
    friend typename _Cp::__self; 
 
    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 
 
_LIBCPP_POP_MACROS 
 
#endif // _LIBCPP___BIT_REFERENCE