stl_deque.h

gcc3.2.1源代码

                             _Alloc_traits<_Tp, _Alloc>::_S_instanceless>
          _Base;
  typedef typename _Base::allocator_type             allocator_type;
  typedef _Deque_iterator<_Tp,_Tp&,_Tp*>             iterator;
  typedef _Deque_iterator<_Tp,const _Tp&,const _Tp*> const_iterator;

  _Deque_base(const allocator_type& __a, size_t __num_elements)
    : _Base(__a), _M_start(), _M_finish()
    { _M_initialize_map(__num_elements); }
  _Deque_base(const allocator_type& __a) 
    : _Base(__a), _M_start(), _M_finish() {}
  ~_Deque_base();    

protected:
  void _M_initialize_map(size_t);
  void _M_create_nodes(_Tp** __nstart, _Tp** __nfinish);
  void _M_destroy_nodes(_Tp** __nstart, _Tp** __nfinish);
  enum { _S_initial_map_size = 8 };

protected:
  iterator _M_start;
  iterator _M_finish;
};


template <class _Tp, class _Alloc>
_Deque_base<_Tp,_Alloc>::~_Deque_base()
{
  if (_M_map) {
    _M_destroy_nodes(_M_start._M_node, _M_finish._M_node + 1);
    _M_deallocate_map(_M_map, _M_map_size);
  }
}

/**
 *  @if maint
 *  @brief Layout storage.
 *  @param  num_elements  The count of T's for which to allocate space at first.
 *  @return   Nothing.
 *
 *  The initial underlying memory layout is a bit complicated...
 *  @endif
*/
template <class _Tp, class _Alloc>
void
_Deque_base<_Tp,_Alloc>::_M_initialize_map(size_t __num_elements)
{
  size_t __num_nodes = 
    __num_elements / __deque_buf_size(sizeof(_Tp)) + 1;

  _M_map_size = max((size_t) _S_initial_map_size, __num_nodes + 2);
  _M_map = _M_allocate_map(_M_map_size);

  _Tp** __nstart = _M_map + (_M_map_size - __num_nodes) / 2;
  _Tp** __nfinish = __nstart + __num_nodes;
    
  try 
    { _M_create_nodes(__nstart, __nfinish); }
  catch(...)
    {
      _M_deallocate_map(_M_map, _M_map_size);
      _M_map = 0;
      _M_map_size = 0;
      __throw_exception_again;
    }
  
  _M_start._M_set_node(__nstart);
  _M_finish._M_set_node(__nfinish - 1);
  _M_start._M_cur = _M_start._M_first;
  _M_finish._M_cur = _M_finish._M_first +
               __num_elements % __deque_buf_size(sizeof(_Tp));
}

template <class _Tp, class _Alloc>
void _Deque_base<_Tp,_Alloc>::_M_create_nodes(_Tp** __nstart, _Tp** __nfinish)
{
  _Tp** __cur;
  try {
    for (__cur = __nstart; __cur < __nfinish; ++__cur)
      *__cur = _M_allocate_node();
  }
  catch(...)
    { 
      _M_destroy_nodes(__nstart, __cur);
      __throw_exception_again; 
    }
}

template <class _Tp, class _Alloc>
void
_Deque_base<_Tp,_Alloc>::_M_destroy_nodes(_Tp** __nstart, _Tp** __nfinish)
{
  for (_Tp** __n = __nstart; __n < __nfinish; ++__n)
    _M_deallocate_node(*__n);
}


/**
 *  @ingroup Containers
 *  @ingroup Sequences
 *
 *  Meets the requirements of a <a href="tables.html#65">container</a>, a
 *  <a href="tables.html#66">reversible container</a>, and a
 *  <a href="tables.html#67">sequence</a>, including the
 *  <a href="tables.html#68">optional sequence requirements</a>.
 *
 *  Placeholder:  see http://www.sgi.com/tech/stl/Deque.html for now.
 *
 *  In previous HP/SGI versions of deque, there was an extra template parameter
 *  so users could control the node size.  This extension turned out to violate
 *  the C++ standard (it can be detected using template template parameters),
 *  and it was removed.
 *
 *  @if maint
 *  Here's how a deque<Tp> manages memory.  Each deque has 4 members:
 *  
 *  - Tp**        _M_map
 *  - size_t      _M_map_size
 *  - iterator    _M_start, _M_finish
 *  
 *  map_size is at least 8.  %map is an array of map_size pointers-to-"nodes".
 *  (The name has nothing to do with the std::map class.)
 *  
 *  A "node" has no specific type name as such, but it is referred to as
 *  "node" in this file.  It is a simple array-of-Tp.  If Tp is very large,
 *  there will be one Tp element per node (i.e., an "array" of one).
 *  For non-huge Tp's, node size is inversely related to Tp size:  the
 *  larger the Tp, the fewer Tp's will fit in a node.  The goal here is to
 *  keep the total size of a node relatively small and constant over different
 *  Tp's, to improve allocator efficiency.
 *  
 *  **** As I write this, the nodes are /not/ allocated using the high-speed
 *  memory pool.  There are 20 hours left in the year; perhaps I can fix
 *  this before 2002.
 *  
 *  Not every pointer in the %map array will point to a node.  If the initial
 *  number of elements in the deque is small, the /middle/ %map pointers will
 *  be valid, and the ones at the edges will be unused.  This same situation
 *  will arise as the %map grows:  available %map pointers, if any, will be on
 *  the ends.  As new nodes are created, only a subset of the %map's pointers
 *  need to be copied "outward".
 *
 *  Class invariants:
 * - For any nonsingular iterator i:
 *    - i.node points to a member of the %map array.  (Yes, you read that
 *      correctly:  i.node does not actually point to a node.)  The member of
 *      the %map array is what actually points to the node.
 *    - i.first == *(i.node)    (This points to the node (first Tp element).)
 *    - i.last  == i.first + node_size
 *    - i.cur is a pointer in the range [i.first, i.last).  NOTE:
 *      the implication of this is that i.cur is always a dereferenceable
 *      pointer, even if i is a past-the-end iterator.
 * - Start and Finish are always nonsingular iterators.  NOTE: this means that
 *   an empty deque must have one node, a deque with <N elements (where N is
 *   the node buffer size) must have one node, a deque with N through (2N-1)
 *   elements must have two nodes, etc.
 * - For every node other than start.node and finish.node, every element in the
 *   node is an initialized object.  If start.node == finish.node, then
 *   [start.cur, finish.cur) are initialized objects, and the elements outside
 *   that range are uninitialized storage.  Otherwise, [start.cur, start.last)
 *   and [finish.first, finish.cur) are initialized objects, and [start.first,
 *   start.cur) and [finish.cur, finish.last) are uninitialized storage.
 * - [%map, %map + map_size) is a valid, non-empty range.  
 * - [start.node, finish.node] is a valid range contained within 
 *   [%map, %map + map_size).  
 * - A pointer in the range [%map, %map + map_size) points to an allocated node
 *   if and only if the pointer is in the range [start.node, finish.node].
 *
 *  Here's the magic:  nothing in deque is "aware" of the discontiguous storage!
 *
 *  The memory setup and layout occurs in the parent, _Base, and the iterator
 *  class is entirely responsible for "leaping" from one node to the next.  All
 *  the implementation routines for deque itself work only through the start
 *  and finish iterators.  This keeps the routines simple and sane, and we can
 *  use other standard algorithms as well.
 *  @endif
*/
template <class _Tp, class _Alloc = allocator<_Tp> >
class deque : protected _Deque_base<_Tp, _Alloc>
{
  // concept requirements
  __glibcpp_class_requires(_Tp, _SGIAssignableConcept)

  typedef _Deque_base<_Tp, _Alloc> _Base;

public:
  typedef _Tp                                value_type;
  typedef value_type*                        pointer;
  typedef const value_type*                  const_pointer;
  typedef value_type&                        reference;
  typedef const value_type&                  const_reference;
  typedef size_t                             size_type;
  typedef ptrdiff_t                          difference_type;

  typedef typename _Base::allocator_type allocator_type;
  allocator_type get_allocator() const { return _Base::get_allocator(); }

  typedef typename _Base::iterator           iterator;
  typedef typename _Base::const_iterator     const_iterator;
  typedef reverse_iterator<const_iterator>   const_reverse_iterator;
  typedef reverse_iterator<iterator>         reverse_iterator;

protected:
  typedef pointer* _Map_pointer;
  static size_t _S_buffer_size() { return __deque_buf_size(sizeof(_Tp)); }

  // Functions controlling memory layout, and nothing else.
  using _Base::_M_initialize_map;
  using _Base::_M_create_nodes;
  using _Base::_M_destroy_nodes;
  using _Base::_M_allocate_node;
  using _Base::_M_deallocate_node;
  using _Base::_M_allocate_map;
  using _Base::_M_deallocate_map;

  /** @if maint
   *  A total of four data members accumulated down the heirarchy.  If the
   *  _Alloc type requires separate instances, then two of them will also be
   *  included in each deque.
   *  @endif
  */
  using _Base::_M_map;
  using _Base::_M_map_size;
  using _Base::_M_start;
  using _Base::_M_finish;

public:                         // Basic accessors
  iterator begin() { return _M_start; }
  iterator end() { return _M_finish; }
  const_iterator begin() const { return _M_start; }
  const_iterator end() const { return _M_finish; }

  reverse_iterator rbegin() { return reverse_iterator(_M_finish); }
  reverse_iterator rend() { return reverse_iterator(_M_start); }
  const_reverse_iterator rbegin() const 
    { return const_reverse_iterator(_M_finish); }
  const_reverse_iterator rend() const 
    { return const_reverse_iterator(_M_start); }

  reference operator[](size_type __n)
    { return _M_start[difference_type(__n)]; }
  const_reference operator[](size_type __n) const 
    { return _M_start[difference_type(__n)]; }

  void _M_range_check(size_type __n) const {
    if (__n >= this->size())
      __throw_out_of_range("deque");
  }

  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]; }

  reference front() { return *_M_start; }
  reference back() {
    iterator __tmp = _M_finish;
    --__tmp;
    return *__tmp;
  }
  const_reference front() const { return *_M_start; }
  const_reference back() const {
    const_iterator __tmp = _M_finish;
    --__tmp;
    return *__tmp;
  }

  size_type size() const { return _M_finish - _M_start; }
  size_type max_size() const { return size_type(-1); }
  bool empty() const { return _M_finish == _M_start; }

public:                         // Constructor, destructor.
  explicit deque(const allocator_type& __a = allocator_type()) 
    : _Base(__a, 0) {}
  deque(const deque& __x) : _Base(__x.get_allocator(), __x.size()) 
    { uninitialized_copy(__x.begin(), __x.end(), _M_start); }
  deque(size_type __n, const value_type& __value,
        const allocator_type& __a = allocator_type()) : _Base(__a, __n)
    { _M_fill_initialize(__value); }

  explicit
  deque(size_type __n)
  : _Base(allocator_type(), __n)
  { _M_fill_initialize(value_type()); }

  // Check whether it's an integral type.  If so, it's not an iterator.
  template<class _InputIterator>
    deque(_InputIterator __first, _InputIterator __last,
          const allocator_type& __a = 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_map(__n);
      _M_fill_initialize(__x);
    }

  template<class _InputIter>
    void
    _M_initialize_dispatch(_InputIter __first, _InputIter __last, __false_type)
    {
      typedef typename iterator_traits<_InputIter>::iterator_category _IterCategory;
      _M_range_initialize(__first, __last, _IterCategory());
    }

  ~deque()
  { _Destroy(_M_start, _M_finish); }

  deque& operator= (const deque& __x) {
    const size_type __len = size();
    if (&__x != this) {
      if (__len >= __x.size())
        erase(copy(__x.begin(), __x.end(), _M_start), _M_finish);
      else {
        const_iterator __mid = __x.begin() + difference_type(__len);
        copy(__x.begin(), __mid, _M_start);
        insert(_M_finish, __mid, __x.end());
      }
    }
    return *this;
  }        

  void swap(deque& __x) {
    std::swap(_M_start, __x._M_start);
    std::swap(_M_finish, __x._M_finish);
    std::swap(_M_map, __x._M_map);
    std::swap(_M_map_size, __x._M_map_size);
  }

public: 
  // 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.

  void _M_fill_assign(size_type __n, const _Tp& __val) {
    if (__n > size()) {
      fill(begin(), end(), __val);
      insert(end(), __n - size(), __val);
    }
    else {
      erase(begin() + __n, end());
      fill(begin(), end(), __val);
    }
  }

  void
  assign(size_type __n, const _Tp& __val)
  { _M_fill_assign(__n, __val); }

  template<class _InputIterator>
    void
    assign(_InputIterator __first, _InputIterator __last)
    {
      typedef typename _Is_integer<_InputIterator>::_Integral _Integral;
      _M_assign_dispatch(__first, __last, _Integral());
    }

private:                        // helper functions for assign() 

  template<class _Integer>
    void
    _M_assign_dispatch(_Integer __n, _Integer __val, __true_type)
    { _M_fill_assign(static_cast<size_type>(__n), static_cast<_Tp>(__val)); }

  template<class _InputIterator>
    void
    _M_assign_dispatch(_InputIterator __first, _InputIterator __last, __false_type)
    {
      typedef typename iterator_traits<_InputIterator>::iterator_category _IterCategory;
      _M_assign_aux(__first, __last, _IterCategory());
    }

  template <class _InputIterator>
  void _M_assign_aux(_InputIterator __first, _InputIterator __last,
                     input_iterator_tag);

  template <class _ForwardIterator>
  void _M_assign_aux(_ForwardIterator __first, _ForwardIterator __last,
                     forward_iterator_tag) {
    size_type __len = distance(__first, __last);
    if (__len > size()) {
      _ForwardIterator __mid = __first;
      advance(__mid, size());
      copy(__first, __mid, begin());
      insert(end(), __mid, __last);
    }
    else
      erase(copy(__first, __last, begin()), end());
  }

public:                         // push_* and pop_*
  
  void
  push_back(const value_type& __t)
  {
    if (_M_finish._M_cur != _M_finish._M_last - 1) {
      _Construct(_M_finish._M_cur, __t);
      ++_M_finish._M_cur;
    }
    else
      _M_push_back_aux(__t);
  }

  void
  push_back()
  {
    if (_M_finish._M_cur != _M_finish._M_last - 1) {
      _Construct(_M_finish._M_cur);
      ++_M_finish._M_cur;
    }
    else
      _M_push_back_aux();
  }