list (仿sgi stl)

#include <iostream>
#include <iterator>
#include <memory>
#include <algorithm>
using namespace std;

template <typename T>    // 結點結構
struct __list_node 
{
	typedef void* void_pointer;
	void_pointer prev;
	void_pointer next;
	T data;
};

template <typename T, typename Ref = T&, typename Ptr = T*>    //迭代器
struct __list_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;

	typedef bidirectional_iterator_tag iterator_category;
	typedef T value_type;
	typedef Ptr pointer;
	typedef Ref reference;
	typedef __list_node<T>* link_type;
	typedef size_t size_type;
	typedef ptrdiff_t difference_type;

	link_type node;     //迭代器實際管理的資源指針

	__list_iterator(link_type x) : node(x) {}
	__list_iterator() {}
	__list_iterator(const iterator &x) : node(x.node) {}

	bool operator==(const self &x) const
	{
		return node == x.node;
	}
	bool operator!=(const self &x) const
	{
		return node != x.node;
	}
	reference operator*() const   //  重載解引用運算符
	{
		return (*node).data;
	}
	reference operator->() const   // 重載箭頭運算符
	{
		return &(operator*());
	}
	self& operator++()   // 前增版本
	{
		node = (link_type)((*node).next);
		return *this;
	}
	self& operator++(int)    // 後增版本
	{
		self tmp = *this;
		++*this;
		return *this;
	}
	self& operator--() 
	{
		node = (link_type)((*node).prev);
		return *this;
	}
	self& operator--(int)
	{
		self tmp = *this;
		--*this;
		return *this;
	}
};

template <typename T, typename Alloc = allocator<T>>
class list
{
protected:
	typedef void* void_pointer;
	typedef __list_node<T> list_node;
	//typedef allocator<T> 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;    // 指針類型
	typedef size_t size_type;
	typedef ptrdiff_t difference_type;

public:
	typedef __list_iterator<T> iterator;
	typedef __list_iterator<T, const T&, const T*> const_iterator;

	typedef reverse_iterator<const_iterator> const_reverse_iterator;
	typedef reverse_iterator<iterator> reverse_iterator;

protected:
	link_type get_node() { return list_node_allocator.allocate(1); } // 分配一個結點的內存 但不構造
	void put_node(link_type p) { list_node_allocator.deallocate(p, 1); } // 釋放指定結點內存 但不析構

	link_type creat_node(const T &x)  //  創建並構造一個結點
	{
		link_type p = get_node();
		list_node_allocator.construct(&(p->data), x);
		return p;
	}
	void destory_node(link_type p) // 析構並且釋放一個結點
	{
		list_node_allocator.destory(&(p->data));
		put_node(p);
	}

protected:
	void empty_initialize() //用於空鏈表的建立
	{
		node = get_node();
		node->next = node;
		node->prev = node;
	}

	void fill_initialize(size_type n, const T& value) // 創建n個值爲value的結點的鏈表
	{
		empty_initialize();
		insert(begin(), n, value);
	}
	
	template <typename InputIterator>
	void range_initialize(InputIterator first, InputIterator last) // 創建一個由區間初始化的鏈表
	{
		empty_initialize();
		insert(begin(), first, last);
	}

protected:
	link_type node; //指向空白尾後結點
	Alloc list_node_allocator; // 管理內存分配回收 

public:
	list() { empty_initialize(); } // 構造一個空鏈表

	list(size_type n, const T &value) { fill_initialize(n, value); } // 以n個相同元素初始化
	explicit list(size_type n) { fill_initialize(n, T()); }

	template <typename InputIterator> // 以一個區間初始化
	list(InputIterator first, InputIterator last)
	{
		range_initialize(first, last);
	}

	list(const list<T, Alloc> &x) // 複製構造
	{
		range_initialize(x.begin(), x.end()); 
	}

	list<T, Alloc>& operator=(const list<T, Alloc>& x);

	~list() // 析構函數 清空鏈表
	{
		clear();
		put_node(node); // 釋放尾後結點所佔的內存
	}

	iterator begin() { return (link_type)((*node).next); }
	const_iterator begin() const { return (link_type)((*node).next); }

	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()); }

	bool empty() const // 判空
	{
		return node->next == node;
	}

	size_type size() const // 調用全局函數distance() 時間複雜度：O(n)
	{
		size_type result = distance(begin(), end());
		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<T, Alloc> &x) // j交換指針
	{
		std::swap(node, x.node);
	}

	iterator insert(iterator position, const T &x) // 在指定位置前插入一個元素
	{
		link_type tmp = creat_node(x);
		tmp->next = position.node;
		tmp->prev = (position.node)->prev;
		(link_type(position.node->prev))->next = tmp;
		position.node->prev = tmp;

	}
	iterator insert(iterator position)
	{
		return insert(position, T());
	}

	template <class InputIterator> // 在指定位置前插入一個區間
	void insert(iterator position, InputIterator first, InputIterator last);

	void insert(iterator pos, size_type n, const T& x); // 在指定位置前插入n個x元素

	void push_front(const T &x) { insert(begin(), x); }
	void push_back(const T &x) { insert(end(), x); }

	iterator erase(iterator position) // 擦除指定結點
	{
		link_type prev_node = (link_type)((position.node)->prev);
		link_type next_node = (link_type)((position.node)->next);
		prev_node->next = next_node;
		next_node->prev = prev_node;
		destory_node(position.node);
		return iterator(next_node);
	}

	iterator erase(iterator first, iterator last); // 擦除一個區間

	void pop_front() { erase(begin()); } // 刪除鏈表首元結點
	void pop_back() // 刪除鏈表最後一個結點
	{
		iterator tmp = end();
		erase(--tmp);
	}

	void resize(size_type new_size, const T &x); // 調整鏈表大小
	void resize(size_type new_size) { resize(new_size, T()); }
	void clear(); // 請空鏈表

protected:
	// 將[first, last)內的元素遷移到position之前
	void transfer(iterator position, iterator first, iterator last)
	{
		if (position != last)
		{
			(*(link_type((*last.node).prev))).next = position.node;
			(*(link_type((*first.node).prev))).next = last.node;
			(*(link_type((*position.node).prev))).next = first.node;
			link_type tmp = link_type((*position.node).prev);
			(*position.node).prev = (*last.node).prev;
			(*last.node).prev = (*first.node).prev;
			(*first.node).prev = tmp;
		}
	}
	
public:
	void splice(iterator position, list& x) // 將鏈表x移動到pos之前 x不能和*this相同
	{
		if (!x.empty())
			transfer(position, x.begin(), x.end());
	}

	void splice(iterator position, list&, iterator i) // 將i所指向元素接合於position之前 pos和i可能指向同一個list
	{
		iterator j = i;
		++j;
		if (position == i || position == j)
		{
			return;
		}
		transfer(position, i, j);
	}

	// 將[first,last)內的所有元素接合於pos之前， pos可能和[first,last)指向同一個list 但pos不能位於[first,last)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();

	//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);
};



// 判斷兩個鏈表是否相等
template <typename T, typename 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 = e1->next;
	link_type n2 = e2->next;
	for (; n1 != e1 && n2 != e2; n1 = (link_type)n1->next, (link_type)n2 = n2->next)
	{
		if (n1->data != n2->data) return false;
	}
	return n1 == e1 && n2 == e2;
}

// 字典序比較鏈表大小
template <typename T, typename 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());
}

template <typename T, typename Alloc>
inline void swap(list<T, Alloc> &x, list<T, Alloc> &y)
{
	x.swap(y);
}

template <typename T, typename Alloc>
list<T, Alloc>& list<T, Alloc>::operator=(const list<T, 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)   // x的元素少於原list
			erase(first1, last1);
		else
			insert(last1, first2, last2); // x的元素多餘原list
	}
	return *this;
}


template <typename T, typename Alloc>
template <typename InputIterator>
void list<T, Alloc>::insert(iterator position, InputIterator first, InputIterator last)
{
	for (; first != last; ++first)
	{
		insert(position, *first);
	}
}

template <typename T, typename Alloc>
void list<T, Alloc>::insert(iterator posistion, size_type n, const T &x)
{
	for (; n > 0; --n)
	{
		insert(posistion, x);
	}
}

template <typename T, typename Alloc>
list<T, Alloc>::iterator list<T, Alloc>::erase(iterator first, iterator last)
{
	while (first != last)
	{
		erase(first++);
		return last;
	}
}

template <typename T, typename 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
		insert(end(), new_size - len, x);
}

template <typename T, typename Alloc>
void list<T, Alloc>::clear()
{
	link_type cur = (link_type)node->next;
	while (cur != node) // 從頭結點到最後一個結點
	{
		link_type tmp = cur;
		cur = (link_type)cur->next;
		destory_node(tmp);
	}
	node->next = node;
	node->prev = node;
}

template <typename T, typename Alloc>
void list<T, Alloc>::remove(const T &value) // 移除特定值的所有結點
{
	iterator first = begin();
	iterator last = end();

	for (first != last)
	{
		iterator next = first;
		++next;
		if (*first == value)
			erase(first);
		first = next;
	}
}

template <typename T, typename Alloc> 
void list<T, Alloc>::unique()    // 刪除容器內所有相鄰的重複結點
{
	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 <typename T, typename Alloc>
void list<T, Alloc>::merge(list<T, Alloc> &x) // 將x合併到*this中去 前提是兩個list分別增序排序過
{
	iterator first1 = begin();
	iterator last1 = end();
	iterator first2 = x.begin();
	iterator last2 = x.end();

	while (first1 != last1 && first2 != last2)
	{
		if (*first1 < *first2)
		{
			iterator next = first2;
			transfer(first1, first2, ++next);
			first2 = next;
		}
		else
			++first1;
	}
	if (first2 != last2)
		transfer(last1, first2, last2);
}

template <typename T, typename Alloc>
void list<T, Alloc>::reverse() // 反轉鏈表
{
	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);
	}
}

// 參考 http://blog.csdn.net/chenhanzhun/article/details/39337331
// 因爲list的迭代器是雙向迭代器 所以不能用全局的sort函數 list內部提供了一個sort成員函數

template <typename T, typename Alloc>
void list<T, Alloc>::sort()
{
	if (node->next == node || link_type(node->next)->next == node)  // 如果是空鏈表或者僅有一個元素 就不進行任何操作
		return;
	list<T, Alloc> carry;  // 起到搬運作用
	list<T, Alloc> counter[64]; // 中轉站 其中對於counter[i]裏面最多的存儲數據爲2^(i+1)個節點 若超出則向高位進位即counter[i+1] 
	while (!empty())
	{
		carry.splice(carry.begin(), *this, begin());//把當前鏈表的第一個節點放在carry鏈表頭
		int i = 0;
		while (i < fill && !counter[i].empty())
		{
			counter[i].merge(carry); // 把鏈表carry合併到counter[i]
			carry.swap(counter[i++]);//交換鏈表carry和counter[i]內容
		}
		carry.swap(counter[i]);//交換鏈表carry和counter[i]內容 
		if (i == fill) ++fill;

		for (int i = 1; i < fill; ++i) counter[i].merge(counter[i - 1]); //把低位不滿足進位的剩餘數據全部有序的合併到上一位  
		swap(counter[fill - 1]);//最後把已排序好的鏈表內容交換到當前鏈表
	}
}