VC STL的list iterator P.J實現

VC++ P.J STL list的實現

<<programmer-13-memory-pool>>

侯捷觀點 - 池內春秋— Memory Pool 的設計哲學和無痛運用

在文章中提到VC STL PJ實現這個版本的的allocator. (內存池與內存分配器).同時自己爲了需要寫一個在數據庫的大量數據緩衝池,類似內存池管理的東西和它的疊加器iterator.剛好借鑑VC list中的iterator的實現代碼,而是將list的代碼看了一下,證實了一些”侯捷觀點 - 池內春秋— Memory Pool 的設計哲學和無痛運用”,另外有一點是PJ的代碼可讀性差是差點,也不見的非常差,看多了也不覺得這可能與習慣有關,感覺PJ的代碼實現簡潔很多, 代碼沒有GCC的實現的STL多,所以看和理解沒有這麼曲折.

 

主要看看它的iterator的實現.其他list的函數很多書籍都有介紹,或者直接看list的代碼實現,這樣理解比較深刻. 清楚iterator實現,以後直接copy過來改改就行

 

STL中爲了類型的安全會使用到衆多的typedef,別看得類型眼花繚亂.J

VC的list模板聲明,它使用到了缺省的allocator內存分配器.下面有它的實現的代碼

 

文件:stddef.h

 

#ifndef _PTRDIFF_T_DEFINED

typedef int ptrdiff_t;

#define _PTRDIFF_T_DEFINED

#endif

 

 

文件:utility

空tag類,主要目的是作iterator trains用

struct input_iterator_tag {};

struct output_iterator_tag {};

struct forward_iterator_tag

         : public input_iterator_tag {};

struct bidirectional_iterator_tag

         : public forward_iterator_tag {};

struct random_access_iterator_tag

         : public bidirectional_iterator_tag  {};

 

//最基層的iterator聲明,實質是一個空類,提供類型定義

template<class _C, class _Ty, class _D = ptrdiff_t>

         struct iterator {

         typedef _C iterator_category;

         typedef _Ty value_type;

         typedef _D distance_type;

         };

 

//最基層的_Bidit聲明,實質是一個空類

template<class _Ty, class _D>

         struct _Bidit : public iterator<bidirectional_iterator_tag,

                   _Ty, _D> {};

 

 

文件:list

 

例如:iterator常使用的方式.

X::iterator it;

for(it = x.begin();it!=x.end();++it)

         ? = *it;

 

這裏涉及了list函數begin(),end(),iterator的!=操作符,*操作符,++操作符.

 

const_iterator在list的中的聲明,其實不必理會這個_Bidit基層類,可以看作沒有.

const_iterator有一個成員變量_Nodeptr _Ptr;保存當前的鏈表節點指針.指針的移動變換通過_Acc這個中間類來實現,在list中定義

 

class const_iterator : public _Bidit<_Ty, difference_type> {

public:

         const_iterator()

                   {}

         const_iterator(_Nodeptr _P)

                   : _Ptr(_P) {}

         const_iterator(const iterator& _X)

                   : _Ptr(_X._Ptr) {}

         const_reference operator*() const

                   {return (_Acc::_Value(_Ptr)); }

         _Ctptr operator->() const

                   {return (&**this); }

         const_iterator& operator++()

                   {_Ptr = _Acc::_Next(_Ptr);

                   return (*this); }

         const_iterator operator++(int)

                  {const_iterator _Tmp = *this;

                  ++*this;

                   return (_Tmp); }

         const_iterator& operator--()

                   {_Ptr = _Acc::_Prev(_Ptr);

                   return (*this); }

         const_iterator operator--(int)

                  {const_iterator _Tmp = *this;

                   --*this;

                   return (_Tmp); }

         bool operator==(const const_iterator& _X) const

                   {return (_Ptr == _X._Ptr); }

         bool operator!=(const const_iterator& _X) const

                   {return (!(*this == _X)); }

         _Nodeptr _Mynode() const

                   {return (_Ptr); }

protected:

         _Nodeptr _Ptr;

         };

 

//iterator在list的中的聲明,它繼承了const_iterator

friend class iterator;

class iterator : public const_iterator {

public:

         iterator()

                   {}

         iterator(_Nodeptr _P)

                   : const_iterator(_P) {}

         reference operator*() const

                   {return (_Acc::_Value(_Ptr)); }

         _Tptr operator->() const

                   {return (&**this); }

         iterator& operator++()

                   {_Ptr = _Acc::_Next(_Ptr);

                   return (*this); }

         iterator operator++(int)

                  {iterator _Tmp = *this;

                  ++*this;

                   return (_Tmp); }

         iterator& operator--()

                   {_Ptr = _Acc::_Prev(_Ptr);

                   return (*this); }

         iterator operator--(int)

                  {iterator _Tmp = *this;

                   --*this;

                   return (_Tmp); }

         bool operator==(const iterator& _X) const

                   {return (_Ptr == _X._Ptr); }

         bool operator!=(const iterator& _X) const

                   {return (!(*this == _X)); }

         };

 

 

template<class _Ty, class _A = allocator<_Ty> >

         class list {

protected:

         struct _Node;

         friend struct _Node;

         typedef _POINTER_X(_Node, _A) _Nodeptr;

 

         //鏈表的數據結構J

         struct _Node {

                  _Nodeptr _Next, _Prev;

                   _Ty _Value;

                   };

         struct _Acc;

         friend struct _Acc;

 

//這個結構只有是用在iterator,設計它的目的是將iterator和指針的移動實現分離.這樣使得//iterator的代碼非常的簡潔和乾淨,注意到他們都是static函數

         struct _Acc {

                  typedef _REFERENCE_X(_Nodeptr, _A) _Nodepref;

                  typedef _A::reference _Vref;

                   static _Nodepref _Next(_Nodeptr _P)

                            {return ((_Nodepref)(*_P)._Next); }

                   static _Nodepref _Prev(_Nodeptr _P)

                            {return ((_Nodepref)(*_P)._Prev); }

                   static _Vref _Value(_Nodeptr _P)

                            {return ((_Vref)(*_P)._Value); }

                   };

public:

         // 類型安全的typedef定義

         typedef list<_Ty, _A> _Myt;

         typedef _A allocator_type;

         typedef _A::size_type size_type;

         typedef _A::difference_type difference_type;

         typedef _A::pointer _Tptr;

         typedef _A::const_pointer _Ctptr;

         typedef _A::reference reference;

         typedef _A::const_reference const_reference;

         typedef _A::value_type value_type;

 

         // iterator的向前聲明

         class iterator;

         class const_iterator;

         friend class const_iterator;

        

//構造函數

         explicit list(const _A& _Al = _A())

                   : allocator(_Al),

                  _Head(_Buynode()), _Size(0) {}

         explicit list(size_type _N, const _Ty& _V = _Ty(),

                   const _A& _Al = _A())

                   : allocator(_Al),

                  _Head(_Buynode()), _Size(0)

                  {insert(begin(), _N, _V); }

         list(const _Myt& _X)

                   : allocator(_X.allocator),

                  _Head(_Buynode()), _Size(0)

                  {insert(begin(), _X.begin(), _X.end()); }

         list(const _Ty *_F, const _Ty *_L, const _A& _Al = _A())

                   : allocator(_Al),

                  _Head(_Buynode()), _Size(0)

                  {insert(begin(), _F, _L); }

         typedef const_iterator _It;

         list(_It _F, _It _L, const _A& _Al = _A())

                   : allocator(_Al),

                  _Head(_Buynode()), _Size(0)

                  {insert(begin(), _F, _L); }

         ~list()

                  {erase(begin(), end());

                  _Freenode(_Head);

                   _Head = 0, _Size = 0; }

         _Myt& operator=(const _Myt& _X)

                   {if (this != &_X)

                            {iterator _F1 = begin();

                            iterator _L1 = end();

                            const_iterator _F2 = _X.begin();

                            const_iterator _L2 = _X.end();

                            for (; _F1 != _L1 && _F2 != _L2; ++_F1, ++_F2)

                                     *_F1 = *_F2;

                            erase(_F1, _L1);

                            insert(_L1, _F2, _L2); }

                   return (*this); }

 

         // 下面是一些常用到涉及iterator的方法

         //  begin(),end()都是返回一個iterator對象,其他類似

         iterator begin()

                   {return (iterator(_Acc::_Next(_Head))); }

         const_iterator begin() const

                   {return (const_iterator(_Acc::_Next(_Head))); }

         iterator end()

                   {return (iterator(_Head)); }

         const_iterator end() const

                   {return (const_iterator(_Head)); }

         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())); }

 

// 下面是一些常用方法

         void resize(size_type _N, _Ty _X = _Ty())

                   {if (size() < _N)

                            insert(end(), _N - size(), _X);

                   else

                            while (_N < size())

                                     pop_back(); }

         size_type size() const

                   {return (_Size); }

         size_type max_size() const

                   {return (allocator.max_size()); }

         bool empty() const

                   {return (size() == 0); }

         _A get_allocator() const

                   {return (allocator); }

         reference front()

                   {return (*begin()); }

         const_reference front() const

                   {return (*begin()); }

         reference back()

                   {return (*(--end())); }

         const_reference back() const

                   {return (*(--end())); }

         void push_front(const _Ty& _X)

                  {insert(begin(), _X); }

         void pop_front()

                  {erase(begin()); }

         void push_back(const _Ty& _X)

                 {insert(end(), _X); }

         void pop_back()

                  {erase(--end()); }

         void assign(_It _F, _It _L)

                  {erase(begin(), end());

                  insert(begin(), _F, _L); }

         void assign(size_type _N, const _Ty& _X = _Ty())

                  {erase(begin(), end());

                  insert(begin(), _N, _X); }

         …………..

};

 

內存分配器實現

很明顯allocate調用_Allocate 模板函數使用了operator new實現,deallocate使用到了delete實現,所以allocate是C++new和delete的淺層包裝類.

 

文件:xmemory

 

#define _FARQ

#define _PDFT         ptrdiff_t

#define _SIZT         size_t

 

template<class _Ty> inline

         _Ty _FARQ *_Allocate(_PDFT _N, _Ty _FARQ *)

         {if (_N < 0)

                   _N = 0;

         return ((_Ty _FARQ *)operator new(

                  (_SIZT)_N * sizeof (_Ty))); }

 

 

template<class _Ty>

         class allocator {

public:

         typedef _SIZT size_type;

         typedef _PDFT difference_type;

         typedef _Ty _FARQ *pointer;

         typedef const _Ty _FARQ *const_pointer;

         typedef _Ty _FARQ& reference;

         typedef const _Ty _FARQ& const_reference;

         typedef _Ty value_type;

         pointer address(reference _X) const

                   {return (&_X); }

         const_pointer address(const_reference _X) const

                   {return (&_X); }

         pointer allocate(size_type _N, const void *)

                   {return (_Allocate((difference_type)_N, (pointer)0)); }

         char _FARQ *_Charalloc(size_type _N)

                   {return (_Allocate((difference_type)_N,

                            (char _FARQ *)0)); }

         void deallocate(void _FARQ *_P, size_type)

                  {operator delete(_P); }

         void construct(pointer _P, const _Ty& _V)

                  {_Construct(_P, _V); }

         void destroy(pointer _P)

                  {_Destroy(_P); }

         _SIZT max_size() const

                   {_SIZT _N = (_SIZT)(-1) / sizeof (_Ty);

                   return (0 < _N ? _N : 1); }

         };

 

 

附錄:

SGI的STL 實現

 

list頭文件

#ifndef __SGI_STL_LIST

#define __SGI_STL_LIST

 

#include <stl_algobase.h>

#include <stl_alloc.h>

#include <stl_construct.h>

#include <stl_uninitialized.h>

#include <stl_list.h>

 

#endif /* __SGI_STL_LIST */

 

 

stl_list.h

 

#ifndef __SGI_STL_INTERNAL_LIST_H

#define __SGI_STL_INTERNAL_LIST_H

 

#include <concept_checks.h>

 

__STL_BEGIN_NAMESPACE

 

#if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)

#pragma set woff 1174

#pragma set woff 1375

#endif

 

struct _List_node_base {

  _List_node_base* _M_next;

  _List_node_base* _M_prev;

};

 

template <class _Tp>

struct _List_node : public _List_node_base {

  _Tp _M_data;

};

 

struct _List_iterator_base {

  typedef size_t                     size_type;

  typedef ptrdiff_t                  difference_type;

  typedef bidirectional_iterator_tag iterator_category;

 

  _List_node_base* _M_node;

 

  _List_iterator_base(_List_node_base* __x) : _M_node(__x) {}

  _List_iterator_base() {}

 

  void _M_incr() { _M_node = _M_node->_M_next; }

  void _M_decr() { _M_node = _M_node->_M_prev; }

 

  bool operator==(const _List_iterator_base& __x) const {

    return _M_node == __x._M_node;

  }

  bool operator!=(const _List_iterator_base& __x) const {

    return _M_node != __x._M_node;

  }

}; 

 

template<class _Tp, class _Ref, class _Ptr>

struct _List_iterator : public _List_iterator_base {

  typedef _List_iterator<_Tp,_Tp&,_Tp*>             iterator;

  typedef _List_iterator<_Tp,const _Tp&,const _Tp*> const_iterator;

  typedef _List_iterator<_Tp,_Ref,_Ptr>             _Self;

 

  typedef _Tp value_type;

  typedef _Ptr pointer;

  typedef _Ref reference;

  typedef _List_node<_Tp> _Node;

 

  _List_iterator(_Node* __x) : _List_iterator_base(__x) {}

  _List_iterator() {}

  _List_iterator(const iterator& __x) : _List_iterator_base(__x._M_node) {}

 

  reference operator*() const { return ((_Node*) _M_node)->_M_data; }

 

#ifndef __SGI_STL_NO_ARROW_OPERATOR

  pointer operator->() const { return &(operator*()); }

#endif /* __SGI_STL_NO_ARROW_OPERATOR */

 

  _Self& operator++() {

    this->_M_incr();

    return *this;

  }

  _Self operator++(int) {

    _Self __tmp = *this;

    this->_M_incr();

    return __tmp;

  }

  _Self& operator--() {

    this->_M_decr();

    return *this;

  }

  _Self operator--(int) {

    _Self __tmp = *this;

    this->_M_decr();

    return __tmp;

  }

};

 

#ifndef __STL_CLASS_PARTIAL_SPECIALIZATION

 

inline bidirectional_iterator_tag

iterator_category(const _List_iterator_base&)

{

  return bidirectional_iterator_tag();

}

 

template <class _Tp, class _Ref, class _Ptr>

inline _Tp*

value_type(const _List_iterator<_Tp, _Ref, _Ptr>&)

{

  return 0;

}

 

inline ptrdiff_t*

distance_type(const _List_iterator_base&)

{

  return 0;

}

 

#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */

 

 

// Base class that encapsulates details of allocators.  Three cases:

// an ordinary standard-conforming allocator, a standard-conforming

// allocator with no non-static data, and an SGI-style allocator.

// This complexity is necessary only because we're worrying about backward

// compatibility and because we want to avoid wasting storage on an

// allocator instance if it isn't necessary.

 

#ifdef __STL_USE_STD_ALLOCATORS

 

// Base for general standard-conforming allocators.

template <class _Tp, class _Allocator, bool _IsStatic>

class _List_alloc_base {

public:

  typedef typename _Alloc_traits<_Tp, _Allocator>::allocator_type

          allocator_type;

  allocator_type get_allocator() const { return _Node_allocator; }

 

  _List_alloc_base(const allocator_type& __a) : _Node_allocator(__a) {}

 

protected:

  _List_node<_Tp>* _M_get_node()

   { return _Node_allocator.allocate(1); }

  void _M_put_node(_List_node<_Tp>* __p)

    { _Node_allocator.deallocate(__p, 1); }

 

protected:

  typename _Alloc_traits<_List_node<_Tp>, _Allocator>::allocator_type

           _Node_allocator;

  _List_node<_Tp>* _M_node;

};

 

// Specialization for instanceless allocators.

 

template <class _Tp, class _Allocator>

class _List_alloc_base<_Tp, _Allocator, true> {

public:

  typedef typename _Alloc_traits<_Tp, _Allocator>::allocator_type

          allocator_type;

  allocator_type get_allocator() const { return allocator_type(); }

 

  _List_alloc_base(const allocator_type&) {}

 

protected:

  typedef typename _Alloc_traits<_List_node<_Tp>, _Allocator>::_Alloc_type

          _Alloc_type;

  _List_node<_Tp>* _M_get_node() { return _Alloc_type::allocate(1); }

  void _M_put_node(_List_node<_Tp>* __p) { _Alloc_type::deallocate(__p, 1); }

 

protected:

  _List_node<_Tp>* _M_node;

};

 

template <class _Tp, class _Alloc>

class _List_base

  : public _List_alloc_base<_Tp, _Alloc,

                            _Alloc_traits<_Tp, _Alloc>::_S_instanceless>

{

public:

  typedef _List_alloc_base<_Tp, _Alloc,

                           _Alloc_traits<_Tp, _Alloc>::_S_instanceless>

          _Base;

  typedef typename _Base::allocator_type allocator_type;

 

  _List_base(const allocator_type& __a) : _Base(__a) {

    _M_node = _M_get_node();

    _M_node->_M_next = _M_node;

    _M_node->_M_prev = _M_node;

  }

  ~_List_base() {

    clear();

    _M_put_node(_M_node);

  }

 

  void clear();

};

 

#else /* __STL_USE_STD_ALLOCATORS */

 

template <class _Tp, class _Alloc>

class _List_base

{

public:

  typedef _Alloc allocator_type;

  allocator_type get_allocator() const { return allocator_type(); }

 

  _List_base(const allocator_type&) {

    _M_node = _M_get_node();

    _M_node->_M_next = _M_node;

    _M_node->_M_prev = _M_node;

  }

  ~_List_base() {

    clear();

    _M_put_node(_M_node);

  }

 

  void clear();

 

protected:

  typedef simple_alloc<_List_node<_Tp>, _Alloc> _Alloc_type;

  _List_node<_Tp>* _M_get_node() { return _Alloc_type::allocate(1); }

  void _M_put_node(_List_node<_Tp>* __p) { _Alloc_type::deallocate(__p, 1); }

 

protected:

  _List_node<_Tp>* _M_node;

};

 

#endif /* __STL_USE_STD_ALLOCATORS */

 

template <class _Tp, class _Alloc>

void

_List_base<_Tp,_Alloc>::clear()

{

  _List_node<_Tp>* __cur = (_List_node<_Tp>*) _M_node->_M_next;

  while (__cur != _M_node) {

    _List_node<_Tp>* __tmp = __cur;

    __cur = (_List_node<_Tp>*) __cur->_M_next;

    _Destroy(&__tmp->_M_data);

    _M_put_node(__tmp);

  }

  _M_node->_M_next = _M_node;

  _M_node->_M_prev = _M_node;

}

 

template <class _Tp, class _Alloc = __STL_DEFAULT_ALLOCATOR(_Tp) >

class list : protected _List_base<_Tp, _Alloc> {

  // requirements:

 

  __STL_CLASS_REQUIRES(_Tp, _Assignable);

 

  typedef _List_base<_Tp, _Alloc> _Base;

protected:

  typedef void* _Void_pointer;

 

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 _List_node<_Tp> _Node;

  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(); }

 

public:

  typedef _List_iterator<_Tp,_Tp&,_Tp*>             iterator;

  typedef _List_iterator<_Tp,const _Tp&,const _Tp*> const_iterator;

 

#ifdef __STL_CLASS_PARTIAL_SPECIALIZATION

  typedef reverse_iterator<const_iterator> const_reverse_iterator;

  typedef reverse_iterator<iterator>       reverse_iterator;

#else /* __STL_CLASS_PARTIAL_SPECIALIZATION */

  typedef reverse_bidirectional_iterator<const_iterator,value_type,

                                         const_reference,difference_type>

          const_reverse_iterator;

  typedef reverse_bidirectional_iterator<iterator,value_type,reference,

                                         difference_type>

          reverse_iterator;

#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */

 

protected:

#ifdef __STL_HAS_NAMESPACES

  using _Base::_M_node;

  using _Base::_M_put_node;

  using _Base::_M_get_node;

#endif /* __STL_HAS_NAMESPACES */

 

protected:

  _Node* _M_create_node(const _Tp& __x)

  {

    _Node* __p = _M_get_node();

    __STL_TRY {

      _Construct(&__p->_M_data, __x);

    }

    __STL_UNWIND(_M_put_node(__p));

    return __p;

  }

 

  _Node* _M_create_node()

  {

    _Node* __p = _M_get_node();

    __STL_TRY {

      _Construct(&__p->_M_data);

    }

    __STL_UNWIND(_M_put_node(__p));

    return __p;

  }

 

public:

  explicit list(const allocator_type& __a = allocator_type()) : _Base(__a) {}

 

  iterator begin()             { return (_Node*)(_M_node->_M_next); }

  const_iterator begin() const { return (_Node*)(_M_node->_M_next); }

 

  iterator end()             { return _M_node; }

  const_iterator end() const { return _M_node; }

 

  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()); }

 

  bool empty() const { return _M_node->_M_next == _M_node; }

  size_type size() const {

    size_type __result = 0;

    distance(begin(), end(), __result);

    return __result;

  }

  size_type max_size() const { return size_type(-1); }

 

  reference front() { return *begin(); }

  const_reference front() const { return *begin(); }

  reference back() { return *(--end()); }

  const_reference back() const { return *(--end()); }

 

  void swap(list<_Tp, _Alloc>& __x) { __STD::swap(_M_node, __x._M_node); }

 

  iterator insert(iterator __position, const _Tp& __x) {

    _Node* __tmp = _M_create_node(__x);

    __tmp->_M_next = __position._M_node;

    __tmp->_M_prev = __position._M_node->_M_prev;

    __position._M_node->_M_prev->_M_next = __tmp;

    __position._M_node->_M_prev = __tmp;

    return __tmp;

  }

  iterator insert(iterator __position) { return insert(__position, _Tp()); }

#ifdef __STL_MEMBER_TEMPLATES

  // Check whether it's an integral type.  If so, it's not an iterator.

 

  template<class _Integer>

  void _M_insert_dispatch(iterator __pos, _Integer __n, _Integer __x,

                          __true_type) {

    _M_fill_insert(__pos, (size_type) __n, (_Tp) __x);

  }

 

  template <class _InputIterator>

  void _M_insert_dispatch(iterator __pos,

                          _InputIterator __first, _InputIterator __last,

                          __false_type);

 

  template <class _InputIterator>

  void insert(iterator __pos, _InputIterator __first, _InputIterator __last) {

    typedef typename _Is_integer<_InputIterator>::_Integral _Integral;

    _M_insert_dispatch(__pos, __first, __last, _Integral());

  }

 

#else /* __STL_MEMBER_TEMPLATES */

  void insert(iterator __position, const _Tp* __first, const _Tp* __last);

  void insert(iterator __position,

              const_iterator __first, const_iterator __last);

#endif /* __STL_MEMBER_TEMPLATES */

  void insert(iterator __pos, size_type __n, const _Tp& __x)

    { _M_fill_insert(__pos, __n, __x); }

  void _M_fill_insert(iterator __pos, size_type __n, const _Tp& __x);

 

  void push_front(const _Tp& __x) { insert(begin(), __x); }

  void push_front() {insert(begin());}

  void push_back(const _Tp& __x) { insert(end(), __x); }

  void push_back() {insert(end());}

 

  iterator erase(iterator __position) {

    _List_node_base* __next_node = __position._M_node->_M_next;

    _List_node_base* __prev_node = __position._M_node->_M_prev;

    _Node* __n = (_Node*) __position._M_node;

    __prev_node->_M_next = __next_node;

    __next_node->_M_prev = __prev_node;

    _Destroy(&__n->_M_data);

    _M_put_node(__n);

    return iterator((_Node*) __next_node);

  }

  iterator erase(iterator __first, iterator __last);

  void clear() { _Base::clear(); }

 

  void resize(size_type __new_size, const _Tp& __x);

  void resize(size_type __new_size) { this->resize(__new_size, _Tp()); }

 

  void pop_front() { erase(begin()); }

  void pop_back() {

    iterator __tmp = end();

    erase(--__tmp);

  }

  list(size_type __n, const _Tp& __value,

       const allocator_type& __a = allocator_type())

    : _Base(__a)

    { insert(begin(), __n, __value); }

  explicit list(size_type __n)

    : _Base(allocator_type())

    { insert(begin(), __n, _Tp()); }

 

#ifdef __STL_MEMBER_TEMPLATES

 

  // We don't need any dispatching tricks here, because insert does all of

  // that anyway. 

  template <class _InputIterator>

  list(_InputIterator __first, _InputIterator __last,

       const allocator_type& __a = allocator_type())

    : _Base(__a)

    { insert(begin(), __first, __last); }

 

#else /* __STL_MEMBER_TEMPLATES */

 

  list(const _Tp* __first, const _Tp* __last,

       const allocator_type& __a = allocator_type())

    : _Base(__a)

    { this->insert(begin(), __first, __last); }

  list(const_iterator __first, const_iterator __last,

       const allocator_type& __a = allocator_type())

    : _Base(__a)

    { this->insert(begin(), __first, __last); }

 

#endif /* __STL_MEMBER_TEMPLATES */

  list(const list<_Tp, _Alloc>& __x) : _Base(__x.get_allocator())

    { insert(begin(), __x.begin(), __x.end()); }

 

  ~list() { }

 

  list<_Tp, _Alloc>& operator=(const list<_Tp, _Alloc>& __x);

 

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

 

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

 

#ifdef __STL_MEMBER_TEMPLATES

 

  template <class _InputIterator>

  void assign(_InputIterator __first, _InputIterator __last) {

    typedef typename _Is_integer<_InputIterator>::_Integral _Integral;

    _M_assign_dispatch(__first, __last, _Integral());

  }

 

  template <class _Integer>

  void _M_assign_dispatch(_Integer __n, _Integer __val, __true_type)

    { _M_fill_assign((size_type) __n, (_Tp) __val); }

 

  template <class _InputIterator>

  void _M_assign_dispatch(_InputIterator __first, _InputIterator __last,

                          __false_type);

 

#endif /* __STL_MEMBER_TEMPLATES */

 

protected:

  void transfer(iterator __position, iterator __first, iterator __last) {

    if (__position != __last) {

      // Remove [first, last) from its old position.

      __last._M_node->_M_prev->_M_next     = __position._M_node;

      __first._M_node->_M_prev->_M_next    = __last._M_node;

      __position._M_node->_M_prev->_M_next = __first._M_node;

 

      // Splice [first, last) into its new position.

      _List_node_base* __tmp      = __position._M_node->_M_prev;

      __position._M_node->_M_prev = __last._M_node->_M_prev;

      __last._M_node->_M_prev     = __first._M_node->_M_prev;

      __first._M_node->_M_prev    = __tmp;

    }

  }

 

public:

  void splice(iterator __position, list& __x) {

    if (!__x.empty())

      this->transfer(__position, __x.begin(), __x.end());

  }

  void splice(iterator __position, list&, iterator __i) {

    iterator __j = __i;

    ++__j;

    if (__position == __i || __position == __j) return;

    this->transfer(__position, __i, __j);

  }

  void splice(iterator __position, list&, iterator __first, iterator __last) {

    if (__first != __last)

      this->transfer(__position, __first, __last);

  }

  void remove(const _Tp& __value);

  void unique();

  void merge(list& __x);

  void reverse();

  void sort();

 

#ifdef __STL_MEMBER_TEMPLATES

  template <class _Predicate> void remove_if(_Predicate);

  template <class _BinaryPredicate> void unique(_BinaryPredicate);

  template <class _StrictWeakOrdering> void merge(list&, _StrictWeakOrdering);

  template <class _StrictWeakOrdering> void sort(_StrictWeakOrdering);

#endif /* __STL_MEMBER_TEMPLATES */

};

 

template <class _Tp, class _Alloc>

inline bool

operator==(const list<_Tp,_Alloc>& __x, const list<_Tp,_Alloc>& __y)

{

  typedef typename list<_Tp,_Alloc>::const_iterator const_iterator;

  const_iterator __end1 = __x.end();

  const_iterator __end2 = __y.end();

 

  const_iterator __i1 = __x.begin();

  const_iterator __i2 = __y.begin();

  while (__i1 != __end1 && __i2 != __end2 && *__i1 == *__i2) {

    ++__i1;

    ++__i2;

  }

  return __i1 == __end1 && __i2 == __end2;

}

 

template <class _Tp, class _Alloc>

inline bool operator<(const list<_Tp,_Alloc>& __x,

                      const list<_Tp,_Alloc>& __y)

{

  return lexicographical_compare(__x.begin(), __x.end(),

                                 __y.begin(), __y.end());

}

 

#ifdef __STL_FUNCTION_TMPL_PARTIAL_ORDER

 

template <class _Tp, class _Alloc>

inline bool operator!=(const list<_Tp,_Alloc>& __x,

                       const list<_Tp,_Alloc>& __y) {

  return !(__x == __y);

}

 

template <class _Tp, class _Alloc>

inline bool operator>(const list<_Tp,_Alloc>& __x,

                      const list<_Tp,_Alloc>& __y) {

  return __y < __x;

}

 

template <class _Tp, class _Alloc>

inline bool operator<=(const list<_Tp,_Alloc>& __x,

                       const list<_Tp,_Alloc>& __y) {

  return !(__y < __x);

}

 

template <class _Tp, class _Alloc>

inline bool operator>=(const list<_Tp,_Alloc>& __x,

                       const list<_Tp,_Alloc>& __y) {

  return !(__x < __y);

}

 

template <class _Tp, class _Alloc>

inline void

swap(list<_Tp, _Alloc>& __x, list<_Tp, _Alloc>& __y)

{

  __x.swap(__y);

}

 

#endif /* __STL_FUNCTION_TMPL_PARTIAL_ORDER */

 

#ifdef __STL_MEMBER_TEMPLATES

 

template <class _Tp, class _Alloc> template <class _InputIter>

void

list<_Tp, _Alloc>::_M_insert_dispatch(iterator __position,

                                      _InputIter __first, _InputIter __last,

                                      __false_type)

{

  for ( ; __first != __last; ++__first)

    insert(__position, *__first);

}

 

#else /* __STL_MEMBER_TEMPLATES */

 

template <class _Tp, class _Alloc>

void

list<_Tp, _Alloc>::insert(iterator __position,

                          const _Tp* __first, const _Tp* __last)

{

  for ( ; __first != __last; ++__first)

    insert(__position, *__first);

}

 

template <class _Tp, class _Alloc>

void

list<_Tp, _Alloc>::insert(iterator __position,

                         const_iterator __first, const_iterator __last)

{

  for ( ; __first != __last; ++__first)

    insert(__position, *__first);

}

 

#endif /* __STL_MEMBER_TEMPLATES */

 

template <class _Tp, class _Alloc>

void

list<_Tp, _Alloc>::_M_fill_insert(iterator __position,

                                  size_type __n, const _Tp& __x)

{

  for ( ; __n > 0; --__n)

    insert(__position, __x);

}

 

template <class _Tp, class _Alloc>

typename list<_Tp,_Alloc>::iterator list<_Tp, _Alloc>::erase(iterator __first,

                                                             iterator __last)

{

  while (__first != __last)

    erase(__first++);

  return __last;

}

 

template <class _Tp, class _Alloc>

void list<_Tp, _Alloc>::resize(size_type __new_size, const _Tp& __x)

{

  iterator __i = begin();

  size_type __len = 0;

  for ( ; __i != end() && __len < __new_size; ++__i, ++__len)

    ;

  if (__len == __new_size)

    erase(__i, end());

  else                          // __i == end()

    insert(end(), __new_size - __len, __x);

}

 

template <class _Tp, class _Alloc>

list<_Tp, _Alloc>& list<_Tp, _Alloc>::operator=(const list<_Tp, _Alloc>& __x)

{

  if (this != &__x) {

    iterator __first1 = begin();

    iterator __last1 = end();

    const_iterator __first2 = __x.begin();

    const_iterator __last2 = __x.end();

    while (__first1 != __last1 && __first2 != __last2)

      *__first1++ = *__first2++;

    if (__first2 == __last2)

      erase(__first1, __last1);

    else

      insert(__last1, __first2, __last2);

  }

  return *this;

}

 

template <class _Tp, class _Alloc>

void list<_Tp, _Alloc>::_M_fill_assign(size_type __n, const _Tp& __val) {

  iterator __i = begin();

  for ( ; __i != end() && __n > 0; ++__i, --__n)

    *__i = __val;

  if (__n > 0)

    insert(end(), __n, __val);

  else

    erase(__i, end());

}

 

#ifdef __STL_MEMBER_TEMPLATES

 

template <class _Tp, class _Alloc> template <class _InputIter>

void

list<_Tp, _Alloc>::_M_assign_dispatch(_InputIter __first2, _InputIter __last2,

                                      __false_type)

{

  iterator __first1 = begin();

  iterator __last1 = end();

  for ( ; __first1 != __last1 && __first2 != __last2; ++__first1, ++__first2)

    *__first1 = *__first2;

  if (__first2 == __last2)

    erase(__first1, __last1);

  else

    insert(__last1, __first2, __last2);

}

 

#endif /* __STL_MEMBER_TEMPLATES */

 

template <class _Tp, class _Alloc>

void list<_Tp, _Alloc>::remove(const _Tp& __value)

{

  iterator __first = begin();

  iterator __last = end();

  while (__first != __last) {

    iterator __next = __first;

    ++__next;

    if (*__first == __value) erase(__first);

    __first = __next;

  }

}

 

template <class _Tp, class _Alloc>

void list<_Tp, _Alloc>::unique()

{

  iterator __first = begin();

  iterator __last = end();

  if (__first == __last) return;

  iterator __next = __first;

  while (++__next != __last) {

    if (*__first == *__next)

      erase(__next);

    else

      __first = __next;

    __next = __first;

  }

}

 

template <class _Tp, class _Alloc>

void list<_Tp, _Alloc>::merge(list<_Tp, _Alloc>& __x)

{

  iterator __first1 = begin();

  iterator __last1 = end();

  iterator __first2 = __x.begin();

  iterator __last2 = __x.end();

  while (__first1 != __last1 && __first2 != __last2)

    if (*__first2 < *__first1) {

      iterator __next = __first2;

      transfer(__first1, __first2, ++__next);

      __first2 = __next;

    }

    else

      ++__first1;

  if (__first2 != __last2) transfer(__last1, __first2, __last2);

}

 

inline void __List_base_reverse(_List_node_base* __p)

{

  _List_node_base* __tmp = __p;

  do {

    __STD::swap(__tmp->_M_next, __tmp->_M_prev);

    __tmp = __tmp->_M_prev;     // Old next node is now prev.

  } while (__tmp != __p);

}

 

template <class _Tp, class _Alloc>

inline void list<_Tp, _Alloc>::reverse()

{

  __List_base_reverse(this->_M_node);

}   

 

template <class _Tp, class _Alloc>

void list<_Tp, _Alloc>::sort()

{

  // Do nothing if the list has length 0 or 1.

  if (_M_node->_M_next != _M_node && _M_node->_M_next->_M_next != _M_node) {

    list<_Tp, _Alloc> __carry;

    list<_Tp, _Alloc> __counter[64];

    int __fill = 0;

    while (!empty()) {

      __carry.splice(__carry.begin(), *this, begin());

      int __i = 0;

      while(__i < __fill && !__counter[__i].empty()) {

        __counter[__i].merge(__carry);

        __carry.swap(__counter[__i++]);

      }

      __carry.swap(__counter[__i]);        

      if (__i == __fill) ++__fill;

    }

 

    for (int __i = 1; __i < __fill; ++__i)

      __counter[__i].merge(__counter[__i-1]);

    swap(__counter[__fill-1]);

  }

}

 

#ifdef __STL_MEMBER_TEMPLATES

 

template <class _Tp, class _Alloc> template <class _Predicate>

void list<_Tp, _Alloc>::remove_if(_Predicate __pred)

{

  iterator __first = begin();

  iterator __last = end();

  while (__first != __last) {

    iterator __next = __first;

    ++__next;

    if (__pred(*__first)) erase(__first);

    __first = __next;

  }

}

 

template <class _Tp, class _Alloc> template <class _BinaryPredicate>

void list<_Tp, _Alloc>::unique(_BinaryPredicate __binary_pred)

{

  iterator __first = begin();

  iterator __last = end();

  if (__first == __last) return;

  iterator __next = __first;

  while (++__next != __last) {

    if (__binary_pred(*__first, *__next))

      erase(__next);

    else

      __first = __next;

    __next = __first;

  }

}

 

template <class _Tp, class _Alloc> template <class _StrictWeakOrdering>

void list<_Tp, _Alloc>::merge(list<_Tp, _Alloc>& __x,

                              _StrictWeakOrdering __comp)

{

  iterator __first1 = begin();

  iterator __last1 = end();

  iterator __first2 = __x.begin();

  iterator __last2 = __x.end();

  while (__first1 != __last1 && __first2 != __last2)

    if (__comp(*__first2, *__first1)) {

      iterator __next = __first2;

      transfer(__first1, __first2, ++__next);

      __first2 = __next;

    }

    else

      ++__first1;

  if (__first2 != __last2) transfer(__last1, __first2, __last2);

}

 

template <class _Tp, class _Alloc> template <class _StrictWeakOrdering>

void list<_Tp, _Alloc>::sort(_StrictWeakOrdering __comp)

{

  // Do nothing if the list has length 0 or 1.

  if (_M_node->_M_next != _M_node && _M_node->_M_next->_M_next != _M_node) {

    list<_Tp, _Alloc> __carry;

    list<_Tp, _Alloc> __counter[64];

    int __fill = 0;

    while (!empty()) {

      __carry.splice(__carry.begin(), *this, begin());

      int __i = 0;

      while(__i < __fill && !__counter[__i].empty()) {

        __counter[__i].merge(__carry, __comp);

        __carry.swap(__counter[__i++]);

      }

      __carry.swap(__counter[__i]);        

      if (__i == __fill) ++__fill;

    }

 

    for (int __i = 1; __i < __fill; ++__i)

      __counter[__i].merge(__counter[__i-1], __comp);

    swap(__counter[__fill-1]);

  }

}

 

#endif /* __STL_MEMBER_TEMPLATES */

 

#if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)

#pragma reset woff 1174

#pragma reset woff 1375

#endif

 

__STL_END_NAMESPACE

 

#endif /* __SGI_STL_INTERNAL_LIST_H */