STL在列表list它是一种经常使用的容器。list不连续双向链表在内存，而且是环形。
理解列表如何操作的详细信息，然后。阅读STL名单上的代码是最好的方法。
G++ 2.91.57。cygnus\cygwin-b20\include\g++\stl_list.h 完整列表 /*
*
* Copyright (c) 1994
* Hewlett-Packard Company
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Hewlett-Packard Company makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
*
* Copyright (c) 1996,1997
* Silicon Graphics Computer Systems, Inc.
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Silicon Graphics makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*/ /* NOTE: This is an internal header file, included by other STL headers.
* You should not attempt to use it directly.
*/ #ifndef __SGI_STL_INTERNAL_LIST_H
#define __SGI_STL_INTERNAL_LIST_H __STL_BEGIN_NAMESPACE #if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)
#pragma set woff 1174
#endif // List结点结构，List是双向的
template <class T>
struct __list_node {
typedef void* void_pointer;
void_pointer next; // 事实上能够设为 __list_node<T>*
void_pointer prev;
T data;
}; //list是一个双向链表，其迭代器能够向前移、向后移
//因此迭代器类型为bidirectional_iterator_tag
template<class T, class Ref, class Ptr>
struct __list_iterator { // 没有继承 std::iterator
typedef __list_iterator<T, T&, T*> iterator;
typedef __list_iterator<T, const T&, const T*> const_iterator;
typedef __list_iterator<T, Ref, Ptr> self; // 没有继承 std::iterator，自定义迭代器5个类别
typedef bidirectional_iterator_tag iterator_category; // (1)
typedef T value_type; // (2)
typedef Ptr pointer; // (3)
typedef Ref reference; // (4)
typedef __list_node<T>* link_type;
typedef size_t size_type;
typedef ptrdiff_t difference_type; // (5) link_type node; // 原生态指针，指向实际的List结点 //迭代器的构造函数
__list_iterator(link_type x) : node(x) {}
__list_iterator() {}
__list_iterator(const iterator& x) : node(x.node) {} // 迭代器须要重载的运算符，为了支持标准算法STL
bool operator==(const self& x) const { return node == x.node; }
bool operator!=(const self& x) const { return node != x.node; } //对迭代器dereference。取的是迭代器所维护的结点的值
reference operator*() const { return (*node).data; } #ifndef __SGI_STL_NO_ARROW_OPERATOR //假设支持->操作
/*
返回的是所维护结点的地址（能够理解为指针）。
这时，能够把迭代器当作原生态指针来调用结点的函数
*/
pointer operator->() const { return &(operator*()); }
#endif /* __SGI_STL_NO_ARROW_OPERATOR */ //迭代器前进、后退的支持
self& operator++() {
node = (link_type)((*node).next);
return *this;
}
self operator++(int) {
self tmp = *this;
++*this;
return tmp;
} self& operator--() {
node = (link_type)((*node).prev);
return *this;
}
self operator--(int) {
self tmp = *this;
--*this;
return tmp;
}
};
//假设编译器不支持partial specialization偏特性化
#ifndef __STL_CLASS_PARTIAL_SPECIALIZATION
template <class T, class Ref, class Ptr>
inline bidirectional_iterator_tag
iterator_category(const __list_iterator<T, Ref, Ptr>&) {
return bidirectional_iterator_tag();
} template <class T, class Ref, class Ptr>
inline T*
value_type(const __list_iterator<T, Ref, Ptr>&) {
return 0;
} template <class T, class Ref, class Ptr>
inline ptrdiff_t*
distance_type(const __list_iterator<T, Ref, Ptr>&) {
return 0;
}
#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */ //以下是List的定义
template <class T, class Alloc = alloc> // 默觉得 alloc 为配置器
class list {
protected:
typedef void* void_pointer;
typedef __list_node<T> list_node;
// List的空间配置器。每次仅仅配置一个结点
typedef simple_alloc<list_node, Alloc> list_node_allocator;
public:
typedef T 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* link_type;
typedef size_t size_type;
typedef ptrdiff_t difference_type; public:
/*
当开发人员定义一个迭代器时list<T>::iterator。首先调用的是
__list_iterator<T, T&, T*>的构造函数。假设有初始值，便会
因此设定迭代器和容器的联结关系
*/
typedef __list_iterator<T, T&, T*> iterator;
typedef __list_iterator<T, const T&, const T*> 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:
// 配置一个结点（未初始化）。返回其指针
link_type get_node() { return list_node_allocator::allocate(); }
// 释放一个结点
void put_node(link_type p) { list_node_allocator::deallocate(p); } // 配置一个结点，并用x初始化
link_type create_node(const T& x) {
link_type p = get_node();
__STL_TRY {
construct(&p->data, x); // 全局函数
}
__STL_UNWIND(put_node(p));
return p;
}
// 销毁一个结点
void destroy_node(link_type p) {
destroy(&p->data); //全局函数
put_node(p);
} protected:
//初始化一个空链表。首尾相连
void empty_initialize() {
node = get_node();
node->next = node;
node->prev = node;
}
//初始化长为n的链表。值都为value
void fill_initialize(size_type n, const T& value) {
empty_initialize();
__STL_TRY {
insert(begin(), n, value);
}
__STL_UNWIND(clear(); put_node(node));
} #ifdef __STL_MEMBER_TEMPLATES
//以迭代器的区间初始化一个链表
template <class InputIterator>
void range_initialize(InputIterator first, InputIterator last) {
empty_initialize();
__STL_TRY {
insert(begin(), first, last);
}
//commit or rollback
__STL_UNWIND(clear(); put_node(node));
}
#else /* __STL_MEMBER_TEMPLATES */
void range_initialize(const T* first, const T* last) {
empty_initialize();
__STL_TRY {
insert(begin(), first, last);
}
__STL_UNWIND(clear(); put_node(node));
}
void range_initialize(const_iterator first, const_iterator last) {
empty_initialize();
__STL_TRY {
insert(begin(), first, last);
}
__STL_UNWIND(clear(); put_node(node));
}
#endif /* __STL_MEMBER_TEMPLATES */ protected:
/*
List仅仅维护这一个结点。它指向List未结点的下一个位置。即头结点。由于List是一个
环形的双向链表。
该结点是空结点，next指向头结点。 */
link_type node; // 能够觉得它是哨兵结点（在算法导论中有讲哨兵结点） public:
list() { empty_initialize(); } // 默认构造函数，空链表。
//指向头结点的迭代器
iterator begin() { return (link_type)((*node).next); }
const_iterator begin() const { return (link_type)((*node).next); } //指向尾结点下一个位置的迭代器。所以返回node
iterator end() { return node; }
const_iterator end() const { return 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());
}
//链表仅仅有node结点时为空链表
bool empty() const { return node->next == node; }
size_type size() const {
size_type result = 0;
distance(begin(), end(), result); // 在<stl_iterator.h>定义，result是引用传递
return result;
}
//链表最大容量。没什么意义吧？
size_type max_size() const { return size_type(-1); }
// 取链表头结点的内容
reference front() { return *begin(); }
const_reference front() const { return *begin(); }
// 取链表尾结点的内容
reference back() { return *(--end()); }
const_reference back() const { return *(--end()); }
//交换两个链表
void swap(list<T, Alloc>& x) { __STD::swap(node, x.node); } // 在迭代器 position 所指位置前插入一个结点。其值为x。 //在函数中 tmp为指针。返回的却是迭代器
iterator insert(iterator position, const T& x) {
link_type tmp = create_node(x); // 生成结点并用x初始化
// 调整指针
tmp->next = position.node;
tmp->prev = position.node->prev;
//prev和next指针都是void*，所以须要指针类型转换
(link_type(position.node->prev))->next = tmp;
position.node->prev = tmp;
return tmp;
}
//在迭代器 position 所指位置前插入一个结点，其值为T的默认值。这也说明List的元素要有默认构造函数
iterator insert(iterator position) { return insert(position, T()); } //在position所指位置前插入多个元素
#ifdef __STL_MEMBER_TEMPLATES
template <class InputIterator>
void insert(iterator position, InputIterator first, InputIterator last);
#else /* __STL_MEMBER_TEMPLATES */
void insert(iterator position, const T* first, const T* last);
void insert(iterator position,
const_iterator first, const_iterator last);
#endif /* __STL_MEMBER_TEMPLATES */
void insert(iterator pos, size_type n, const T& x);
void insert(iterator pos, int n, const T& x) {
insert(pos, (size_type)n, x);
}
void insert(iterator pos, long n, const T& x) {
insert(pos, (size_type)n, x);
} // 在头结点前插入元素
void push_front(const T& x) { insert(begin(), x); }
// 在尾结点后插入元素
void push_back(const T& x) { insert(end(), x); } // 移除迭代器 position 所指结点
iterator erase(iterator position) {
link_type next_node = link_type(position.node->next);
link_type prev_node = link_type(position.node->prev);
prev_node->next = next_node;
next_node->prev = prev_node;
destroy_node(position.node);
return iterator(next_node);
}
iterator erase(iterator first, iterator last);
void resize(size_type new_size, const T& x);
void resize(size_type new_size) { resize(new_size, T()); }
void clear(); // 移除头结点
void pop_front() { erase(begin()); }
// 移除尾结点
void pop_back() {
iterator tmp = end();
erase(--tmp);
}
//几个构造函数
list(size_type n, const T& value) { fill_initialize(n, value); }
list(int n, const T& value) { fill_initialize(n, value); }
list(long n, const T& value) { fill_initialize(n, value); }
explicit list(size_type n) { fill_initialize(n, T()); } //用迭代器区间初始化List
#ifdef __STL_MEMBER_TEMPLATES
template <class InputIterator>
list(InputIterator first, InputIterator last) {
range_initialize(first, last);
} #else /* __STL_MEMBER_TEMPLATES */
list(const T* first, const T* last) { range_initialize(first, last); }
list(const_iterator first, const_iterator last) {
range_initialize(first, last);
}
#endif /* __STL_MEMBER_TEMPLATES */
//用一个List初始化
list(const list<T, Alloc>& x) {
range_initialize(x.begin(), x.end());
}
~list() {
clear();//清除全部结点。哨兵结点除外
put_node(node);//释放唯一的一个结点
}
list<T, Alloc>& operator=(const list<T, Alloc>& x); protected:
// 将[first,last) 內的全部元素搬移到position 前，不包含last元素。 void transfer(iterator position, iterator first, iterator last) {
if (position != last) {
/*
要把[first,last)在原有链表去除，然后安接到position前
(1)-(7)步相应后面的图
*/
(*(link_type((*last.node).prev))).next = position.node; // (1)
(*(link_type((*first.node).prev))).next = last.node; // (2)
(*(link_type((*position.node).prev))).next = first.node; // (3)
link_type tmp = link_type((*position.node).prev); // (4)
(*position.node).prev = (*last.node).prev; // (5)
(*last.node).prev = (*first.node).prev; // (6)
(*first.node).prev = tmp; // (7)
}
} public:
// 將 x 链表插入到 position 所指位置之前。x 不是 *this。 void splice(iterator position, list& x) {
if (!x.empty())
transfer(position, x.begin(), x.end());
}
// 將 i 所指元素插入到 position 所指位置之前。position 和i 可在同一个list。
void splice(iterator position, list&, iterator i) {
iterator j = i;
++j;
if (position == i || position == j) return;
transfer(position, i, j);
}
// 將 [first,last) 內的全部元素插入到 position 所指位置之前。
// position 和[first,last)可指在同一个list，
// 但position不能位于[first,last)之內。
void splice(iterator position, list&, iterator first, iterator last) {
if (first != last)
transfer(position, first, last);
}
void remove(const T& 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 */ friend bool operator== __STL_NULL_TMPL_ARGS (const list& x, const list& y);
}; //推断2个链表是否同样
template <class T, class Alloc>
inline bool operator==(const list<T,Alloc>& x, const list<T,Alloc>& y) {
typedef typename list<T,Alloc>::link_type link_type;
link_type e1 = x.node;
link_type e2 = y.node;
link_type n1 = (link_type) e1->next;
link_type n2 = (link_type) e2->next;
for ( ; n1 != e1 && n2 != e2 ;
n1 = (link_type) n1->next, n2 = (link_type) n2->next)
if (n1->data != n2->data)
return false;
return n1 == e1 && n2 == e2;
} //lexicographical_compare是STL算法
template <class T, class Alloc>
inline bool operator<(const list<T, Alloc>& x, const list<T, Alloc>& y) {
return lexicographical_compare(x.begin(), x.end(), y.begin(), y.end());
} #ifdef __STL_FUNCTION_TMPL_PARTIAL_ORDER template <class T, class Alloc>
//交换两个链表
inline void swap(list<T, Alloc>& x, list<T, Alloc>& y) {
x.swap(y);
} #endif /* __STL_FUNCTION_TMPL_PARTIAL_ORDER */ #ifdef __STL_MEMBER_TEMPLATES
//在position之前插入迭代器区间的元素
template <class T, class Alloc> template <class InputIterator>
void list<T, Alloc>::insert(iterator position,
InputIterator first, InputIterator last) {
for ( ; first != last; ++first)
insert(position, *first);
} #else /* __STL_MEMBER_TEMPLATES */ template <class T, class Alloc>
void list<T, Alloc>::insert(iterator position, const T* first, const T* last) {
for ( ; first != last; ++first)
insert(position, *first);
} template <class T, class Alloc>
void list<T, Alloc>::insert(iterator position,
const_iterator first, const_iterator last) {
for ( ; first != last; ++first)
insert(position, *first);
} #endif /* __STL_MEMBER_TEMPLATES */ //在position位置之前插入n个元素x
template <class T, class Alloc>
void list<T, Alloc>::insert(iterator position, size_type n, const T& x) {
for ( ; n > 0; --n)
insert(position, x);
}
//擦除两个迭代器区间之间的元素
template <class T, class Alloc>
list<T,Alloc>::iterator list<T, Alloc>::erase(iterator first, iterator last) {
while (first != last) erase(first++);
return last;
}
/*
又一次调整链表大小为 new_size
假设new_size大于原来的链表。则在链表末尾插入x
假设new_size小于原来的链表，则在末尾直接擦除多余的元素
*/
template <class T, class Alloc>
void list<T, Alloc>::resize(size_type new_size, const T& 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);
} // 清除全部结点，（哨兵结点除外）
template <class T, class Alloc>
void list<T, Alloc>::clear()
{
link_type cur = (link_type) node->next; // begin()
while (cur != node) {
link_type tmp = cur;
cur = (link_type) cur->next;
destroy_node(tmp);
}
// 恢复哨兵结点。链表此时为空链表
node->next = node;
node->prev = node;
}
//重载赋值=操作符
template <class T, class Alloc>
list<T, Alloc>& list<T, Alloc>::operator=(const list<T, Alloc>& x) {
if (this != &x) {//防止自身赋值
iterator first1 = begin();
iterator last1 = end();
const_iterator first2 = x.begin();
const_iterator last2 = x.end();
//通过更改结点的值来赋值
while (first1 != last1 && first2 != last2) *first1++ = *first2++;
/*
假设x链表小于this链表，擦除多余的。否则在this后面插入
*/
if (first2 == last2)
erase(first1, last1);
else
insert(last1, first2, last2);
}
return *this;
} // 将数值为value的结点移除
template <class T, class Alloc>
void list<T, Alloc>::remove(const T& value) {
iterator first = begin();
iterator last = end();
while (first != last) { // 巡访每一個節點
iterator next = first;
++next;
if (*first == value) erase(first); // 找到就移除
first = next;
}
} // 移除数值同样的连续元素
template <class T, class Alloc>
void list<T, Alloc>::unique() {
iterator first = begin();
iterator last = end();
if (first == last) return;
iterator next = first;
while (++next != last) {
if (*first == *next)//假设数值同样，则移除后面的那个
erase(next);
else
first = next;
next = first;
}
} //将x合并到*this上面。两个链表都要先经过递增排序。相当于合并排序的最后一步
template <class T, class Alloc>
void list<T, Alloc>::merge(list<T, Alloc>& x) {
iterator first1 = begin();
iterator last1 = end();
iterator first2 = x.begin();
iterator last2 = x.end(); //注意：此时已经假设两个链表都已经非递减排序好了
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);
} // 将 *this 的內容逆向重置
template <class T, class Alloc>
void list<T, Alloc>::reverse() { //假设链表是空，或者仅仅有一个元素，就不做不论什么处理
//不是用size()==0或size()==1来推断。由于这样比較慢
if (node->next == node || link_type(node->next)->next == node) return;
iterator first = begin();
++first;
while (first != end()) {
iterator old = first;
++first;
transfer(begin(), old, first);
}
} /*
STL的sort算法仅仅能接受迭代器类型为RamdonAccessIterator的容器。所以list无法
使用，故自己重写排序算法。这里使用的是高速排序。详细能够參考这里：<a target=_blank href="http://blog.csdn.net/zhizichina/article/details/7538974">http://blog.csdn.net/zhizichina/article/details/7538974</a>
*/
template <class T, class Alloc>
void list<T, Alloc>::sort() { if (node->next == node || link_type(node->next)->next == node) return; // carry作为tmp
list<T, Alloc> carry;
list<T, 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
/*
pred是一个函数，假设容器内的元素经过pred函数推断为真。则移除
*/
template <class T, class Alloc> template <class Predicate>
void list<T, 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;
}
}
/*
依据函数binary_pred来推断是否移除两个相邻的结点
*/
template <class T, class Alloc> template <class BinaryPredicate>
void list<T, 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;
}
}
/*
假设两个链表均已经有序，用comp函数来推断怎样合并两个链表
*/
template <class T, class Alloc> template <class StrictWeakOrdering>
void list<T, Alloc>::merge(list<T, 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);
}
/*
用函数comp来推断怎样排序链表
*/
template <class T, class Alloc> template <class StrictWeakOrdering>
void list<T, Alloc>::sort(StrictWeakOrdering comp) {
if (node->next == node || link_type(node->next)->next == node) return;
list<T, Alloc> carry;
list<T, 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
#endif __STL_END_NAMESPACE #endif /* __SGI_STL_INTERNAL_LIST_H */ // Local Variables:
// mode:C++
// End:
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