void _Init_bounds() {
    _M_iter_list._Orphan(_M_start);
    _M_iter_list._Orphan(_M_finish);
  }
  void _Invalidate_iterator(const _Bit_iterator& __it) { 
    __invalidate_iterator(&_M_iter_list,__it);
  }
  void _Invalidate_all() {
    _M_iter_list._Invalidate_all();
  }
# endif
};


// The next few lines are confusing.  What we're doing is declaring a
//  partial specialization of vector<T, Alloc> if we have the necessary
//  compiler support.  Otherwise, we define a class bit_vector which uses
//  the default allocator. 

#if defined(__STL_CLASS_PARTIAL_SPECIALIZATION) \
 && !defined(__STL_PARTIAL_SPECIALIZATION_BUG) && ! defined(__STL_NO_BOOL)
# define __SGI_STL_VECBOOL_TEMPLATE
# define __BVEC_TMPL_HEADER template <class _Alloc>
#else
# undef __SGI_STL_VECBOOL_TEMPLATE
# ifdef __STL_NO_BOOL
#  define __BVEC_TMPL_HEADER
# else
#  define __BVEC_TMPL_HEADER __STL_TEMPLATE_NULL
# endif
# define _Alloc __STL_DEFAULT_ALLOCATOR(bool)
#endif

#ifdef __STL_NO_BOOL
# define __BVECTOR_QUALIFIED bit_vector
# define __BVECTOR           bit_vector
#else
# ifdef __SGI_STL_VECBOOL_TEMPLATE
#  define __BVECTOR_QUALIFIED vector<bool, _Alloc>
# else
#  define __BVECTOR_QUALIFIED vector<bool>
# endif
#ifdef __STL_PARTIAL_SPEC_NEEDS_TEMPLATE_ARGS
# define __BVECTOR __BVECTOR_QUALIFIED
#else
# define __BVECTOR vector
#endif
#endif


__BVEC_TMPL_HEADER
class __BVECTOR_QUALIFIED : public _Bvector_base<_Alloc >
{
  typedef _Bvector_base<_Alloc > _Base;
  typedef __BVECTOR_QUALIFIED _Self;
public:
  typedef bool value_type;
  typedef size_t size_type;
  typedef ptrdiff_t difference_type; 
  typedef _Bit_reference reference;
  typedef bool const_reference;
  typedef _Bit_reference* pointer;
  typedef const bool* const_pointer;

  typedef _Bit_iterator                iterator;
  typedef _Bit_const_iterator          const_iterator;

#if defined ( __STL_CLASS_PARTIAL_SPECIALIZATION ) && \
  ! defined (__STL_PARTIAL_SPECIALIZATION_BUG)
  typedef __STLPORT_STD::reverse_iterator<const_iterator> const_reverse_iterator;
  typedef __STLPORT_STD::reverse_iterator<iterator> reverse_iterator;
#else /* __STL_CLASS_PARTIAL_SPECIALIZATION */
# if defined (__STL_MSVC50_COMPATIBILITY)
  typedef __STLPORT_STD::reverse_iterator<const_iterator, value_type, const_reference, 
  const_pointer, difference_type> const_reverse_iterator;
  typedef __STLPORT_STD::reverse_iterator<iterator, value_type, reference, reference*, 
  difference_type> reverse_iterator;
# else
  typedef __STLPORT_STD::reverse_iterator<const_iterator, value_type, const_reference, 
                                  difference_type> const_reverse_iterator;
  typedef __STLPORT_STD::reverse_iterator<iterator, value_type, reference, difference_type>
          reverse_iterator;
# endif
#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */

# ifdef __SGI_STL_VECBOOL_TEMPLATE
  typedef typename _Base::allocator_type allocator_type;
# else
  typedef _Base::allocator_type allocator_type;
# endif

#if defined( __STL_HAS_NAMESPACES )
  __STL_USING_BASE_MEMBER _Bvector_base<_Alloc >::get_allocator;
protected:
  __STL_USING_BASE_MEMBER _Bvector_base<_Alloc >::_M_bit_alloc;
  __STL_USING_BASE_MEMBER _Bvector_base<_Alloc >::_M_deallocate;
  __STL_USING_BASE_MEMBER _Bvector_base<_Alloc >::_M_start;
  __STL_USING_BASE_MEMBER _Bvector_base<_Alloc >::_M_finish;
  __STL_USING_BASE_MEMBER _Bvector_base<_Alloc >::_M_end_of_storage;
# ifdef __STL_DEBUG
  __STL_USING_BASE_MEMBER _Bvector_base<_Alloc >::_M_iter_list;
# endif
#endif /* __STL_HAS_NAMESPACES */

protected:
# if defined (__STL_DEBUG)
# define _Make_iterator(__x,__y,__z) iterator(&_M_iter_list,__x,__y,__z)
# define _Make_const_iterator(__x,__y,__z) const_iterator(&_M_iter_list,__x,__y,__z)
# else
# define _Make_iterator(__x,__y,__z) iterator(__x,__y)
# define _Make_const_iterator(__x,__y,__z) const_iterator(__x,__y)
# endif

  void _M_initialize(size_type __n) {
    unsigned int* __q = _M_bit_alloc(__n);
    _M_end_of_storage._M_data = __q + (__n + __WORD_BIT - 1)/__WORD_BIT;
    __stl_debug_do(_M_iter_list._Safe_init(&_M_start));
    _M_start = _Make_iterator(__q, 0, false);
    __stl_debug_do(_M_start._Set_overrun(true));
    _M_finish = _M_start + difference_type(__n);
    __stl_debug_do(_Init_bounds());
  }
  void _M_insert_aux(iterator __position, bool __x) {
    __stl_debug_do(_M_finish._Set_overrun(true));
    if (_M_finish._M_p != _M_end_of_storage._M_data) {
      copy_backward(__position, _M_finish, _M_finish + 1);
      *__position = __x;
      ++_M_finish;
    }
    else {
      size_type __len = size() ? 2 * size() : __WORD_BIT;
      unsigned int* __q = _M_bit_alloc(__len);
      iterator __i = copy(begin(), __position, _Make_iterator(__q, 0, true));
      *__i++ = __x;
      _M_finish = copy(__position, end(), __i);
      __stl_debug_do(_M_iter_list._Orphan(_M_finish));
      _M_deallocate();
      _M_end_of_storage._M_data = __q + (__len + __WORD_BIT - 1)/__WORD_BIT;
      _M_start = _Make_iterator(__q, 0, false);
      __stl_debug_do(_M_iter_list._Orphan(_M_start));
    }
    __stl_debug_do(_M_finish._Set_overrun(false));
  }

#ifdef __STL_MEMBER_TEMPLATES
  template <class _InputIterator>
  void _M_initialize_range(_InputIterator __first, _InputIterator __last,
			input_iterator_tag) {
    __stl_debug_check(__check_range(__first,__last));
    __stl_debug_do(_Safe_init(&_M_start));
    _M_start = iterator();
    _M_finish = iterator();
    __stl_debug_do(_Init_bounds());
    _M_end_of_storage._M_data = 0;
# if defined (__STL_DEBUG) && defined (__STL_USE_EXCEPTIONS)
    try {
# endif
      for ( ; __first != __last; ++__first) 
        push_back(*__first);
# if defined (__STL_DEBUG) && defined (__STL_USE_EXCEPTIONS)
    }
    catch (...) {
      __stl_debug_do(_M_start._Invalidate());
      __stl_debug_do(_M_finish._Invalidate());
      __stl_debug_do(_M_iter_list._Invalidate());        
    }
# endif
  }

  template <class _ForwardIterator>
  void _M_initialize_range(_ForwardIterator __first, _ForwardIterator __last,
                           forward_iterator_tag) {
    size_type __n = 0;
    distance(__first, __last, __n);
    _M_initialize(__n);
    copy(__first, __last, _M_start);
  }

  template <class _InputIterator>
  void _M_insert_range(iterator __pos,
                       _InputIterator __first, _InputIterator __last,
                       input_iterator_tag) {
    for ( ; __first != __last; ++__first) {
      __pos = insert(__pos, *__first);
      ++__pos;
    }
  }

  template <class _ForwardIterator>
  void _M_insert_range(iterator __position,
                       _ForwardIterator __first, _ForwardIterator __last,
                       forward_iterator_tag) {
    __stl_debug_check(__check_range(__first,__last));
    if (__first != __last) {
      size_type __n = 0;
      distance(__first, __last, __n);
      __stl_debug_do(_M_finish._Set_overrun(true));
      __stl_debug_do(__position._Set_overrun(true));
      if (capacity() - size() >= __n) {
        copy_backward(__position, end(), _M_finish + difference_type(__n));
        copy(__first, __last, __position);
        _M_finish += difference_type(__n);
      }
      else {
        size_type __len = size() + max(size(), __n);
        unsigned int* __q = _M_bit_alloc(__len);
        iterator __i = copy(begin(), __position, _Make_iterator(__q, 0, true));
        __i = copy(__first, __last, __i);
        _M_finish = copy(__position, end(), __i);
	__stl_debug_do(_M_iter_list._Orphan(_M_finish));
        _M_deallocate();
        _M_end_of_storage._M_data = __q + (__len + __WORD_BIT - 1)/__WORD_BIT;
        _M_start = _Make_iterator(__q, 0, false);
	__stl_debug_do(_M_iter_list._Orphan(_M_start));
      }
    }
    __stl_debug_do(_M_finish._Set_overrun(false));
  }      

#endif /* __STL_MEMBER_TEMPLATES */

public:
  iterator begin() { return _M_start; }
  const_iterator begin() const { return *(const const_iterator*)&_M_start; }
  iterator end() { return _M_finish; }
  const_iterator end() const { return *(const const_iterator*)&_M_finish; }

  reverse_iterator rbegin() { return reverse_iterator(end()); }
  const_reverse_iterator rbegin() const { 
    return const_reverse_iterator(end()); 
  }
  reverse_iterator rend() { return reverse_iterator(begin()); }
  const_reverse_iterator rend() const { 
    return const_reverse_iterator(begin()); 
  }

  size_type size() const { return size_type(end() - begin()); }
  size_type max_size() const { return size_type(-1); }
  size_type capacity() const {
    return size_type(_Make_const_iterator(_M_end_of_storage._M_data, 0, false) - begin());
  }
  bool empty() const { return begin() == end(); }
  reference operator[](size_type __n) 
  { return *(begin() + difference_type(__n)); }
  const_reference operator[](size_type __n) const 
  { return *(begin() + difference_type(__n)); }

#ifdef __STL_THROW_RANGE_ERRORS
  void _M_range_check(size_type __n) const {
    if (__n >= this->size())
      __stl_throw_range_error("vector<bool>");
  }

  reference at(size_type __n)
    { _M_range_check(__n); return (*this)[__n]; }
  const_reference at(size_type __n) const
    { _M_range_check(__n); return (*this)[__n]; }
#endif /* __STL_THROW_RANGE_ERRORS */


  explicit __BVECTOR(const allocator_type& __a = 
		     __STL_ALLOC_INSTANCE(allocator_type))
    : _Bvector_base<_Alloc >(__a) {}

  __BVECTOR(size_type __n, bool __value,
            const allocator_type& __a = 
	    __STL_ALLOC_INSTANCE(allocator_type))
    : _Bvector_base<_Alloc >(__a)
  {
    _M_initialize(__n);
    fill(_M_start._M_p, (__chunk_type*)_M_end_of_storage._M_data, __value ? ~0 : 0);
  }

  explicit __BVECTOR(size_type __n)
    : _Bvector_base<_Alloc >(allocator_type())
  {
    _M_initialize(__n);
    fill(_M_start._M_p, (__chunk_type*)_M_end_of_storage._M_data, 0);
  }

  __BVECTOR(const _Self& __x) : _Bvector_base<_Alloc >(__x.get_allocator()) {
    _M_initialize(__x.size());
    copy(__x.begin(), __x.end(), _M_start);
  }

#if defined (__STL_MEMBER_TEMPLATES) && !(defined (__GNUC__) && __GNUC_MINOR__ < 90) 
  // Check whether it's an integral type.  If so, it's not an iterator.
  template <class _InputIterator>
  __BVECTOR(_InputIterator __first, _InputIterator __last,
            const allocator_type& __a = __STL_ALLOC_INSTANCE(allocator_type))
    : _Base(__a)
  {
    typedef typename _Is_integer<_InputIterator>::_Integral _Integral;
    _M_initialize_dispatch(__first, __last, _Integral());
  }
    
  template <class _Integer>
  void _M_initialize_dispatch(_Integer __n, _Integer __x, __true_type) {
    _M_initialize(__n);
    fill(_M_start._M_p, _M_end_of_storage._M_data, __x ? ~0 : 0);
  }
    
  template <class _InputIterator>
  void _M_initialize_dispatch(_InputIterator __first, _InputIterator __last,
                              __false_type) {
    _M_initialize_range(__first, __last, __ITERATOR_CATEGORY(__first));
  }
#else /* __STL_MEMBER_TEMPLATES */
  __BVECTOR(const_iterator __first, const_iterator __last,
            const allocator_type& __a = __STL_ALLOC_INSTANCE(allocator_type))
    : _Bvector_base<_Alloc >(__a)
  {
    size_type __n = 0;
    distance(__first, __last, __n);
    _M_initialize(__n);
    copy(__first, __last, _M_start);
  }
  __BVECTOR(const bool* __first, const bool* __last,
            const allocator_type& __a = __STL_ALLOC_INSTANCE(allocator_type))
    : _Bvector_base<_Alloc >(__a)
  {
    size_type __n = 0;
    distance(__first, __last, __n);
    _M_initialize(__n);
    copy(__first, __last, _M_start);
  }
#endif /* __STL_MEMBER_TEMPLATES */

  ~__BVECTOR() { }

  __BVECTOR_QUALIFIED& operator=(const __BVECTOR_QUALIFIED& __x) {
    if (&__x == this) return *this;
    __stl_debug_do(_Invalidate_all());
    if (__x.size() > capacity()) {
      _M_deallocate();
      _M_initialize(__x.size());
    }
    copy(__x.begin(), __x.end(), begin());
    _M_finish = begin() + difference_type(__x.size());
    __stl_debug_do(_M_iter_list._Orphan(_M_finish));
    return *this;
  }

  // assign(), a generalized assignment member function.  Two
  // versions: one that takes a count, and one that takes a range.
  // The range version is a member template, so we dispatch on whether
  // or not the type is an integer.