STL源码剖析 - 第5章 关联式容器 - multiset

5.5 multiset

       multiset的特性及其用法和set完全相同，唯一的区别就是multiset允许键值key重复，因此multiset的插入操作采用的是底层RB-Tree的insert_equal()(可以插入重复的键)而非insert_unique()。本文的源码出自SGI
STL中的<stl_multiset.h>文件。

#ifndef __SGI_STL_INTERNAL_MULTISET_H
#define __SGI_STL_INTERNAL_MULTISET_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

//multiset的特性及其用法和set完全相同，唯一的区别就是multiset允许键值key重复
//因此multiset的插入操作采用的是底层RB-Tree的insert_equal()而非insert_unique()
//有关set容器的剖析见前面博文

// Forward declaration of operators <and ==, needed for friend declaration.

//multiset内部元素默认使用递增排序less
//用户可自行制定比较类型
//内部维护的数据结构是红黑树, 具有非常优秀的最坏情况的时间复杂度
template <class _Key, class _Compare__STL_DEPENDENT_DEFAULT_TMPL(less<_Key>),
class _Alloc = __STL_DEFAULT_ALLOCATOR(_Key) >
class multiset;

template <class _Key, class _Compare,class _Alloc>
inline bool operator==(constmultiset<_Key,_Compare,_Alloc>& __x,
constmultiset<_Key,_Compare,_Alloc>& __y);

template <class _Key, class _Compare,class _Alloc>
inline bool operator<(constmultiset<_Key,_Compare,_Alloc>& __x,
constmultiset<_Key,_Compare,_Alloc>& __y);

template <class _Key, class _Compare,class _Alloc>
class multiset {
//requirements:

__STL_CLASS_REQUIRES(_Key, _Assignable);
__STL_CLASS_BINARY_FUNCTION_CHECK(_Compare, bool, _Key, _Key);

public:

//typedefs:

//以下的定义与set相同
typedef _Key key_type;
typedef _Key value_type;
typedef _Compare key_compare;
typedef _Compare value_compare;
private:
//底层机制是采用RB-Tree
typedef_Rb_tree<key_type, value_type,
_Identity<value_type>,key_compare, _Alloc> _Rep_type;
_Rep_type _M_t; // red-black treerepresenting multiset
public:
typedef typename _Rep_type::const_pointer pointer;
typedef typename _Rep_type::const_pointer const_pointer;
typedef typename _Rep_type::const_reference reference;
typedef typename _Rep_type::const_reference const_reference;
typedef typename _Rep_type::const_iterator iterator;
typedef typename _Rep_type::const_iterator const_iterator;
typedef typename _Rep_type::const_reverse_iterator reverse_iterator;
typedef typename _Rep_type::const_reverse_iteratorconst_reverse_iterator;
typedef typename _Rep_type::size_type size_type;
typedef typename _Rep_type::difference_type difference_type;
typedef typename _Rep_type::allocator_type allocator_type;

//allocation/deallocation
/*
构造函数
multiset();
explicitmultiset (const key_compare& comp = key_compare(),
const allocator_type& alloc =allocator_type());

template<class InputIterator>
multiset(InputIterator first, InputIterator last,
constkey_compare& comp = key_compare(),
constallocator_type& alloc = allocator_type());

multiset(const multiset& x);
*/

multiset() : _M_t(_Compare(), allocator_type()) {}
explicit multiset(const _Compare& __comp,
const allocator_type&__a = allocator_type())
:_M_t(__comp, __a) {}

#ifdef __STL_MEMBER_TEMPLATES

//multiset的插入操作采用的是底层RB-Tree的insert_equal()而非insert_unique()
template <class _InputIterator>
multiset(_InputIterator __first, _InputIterator __last)
:_M_t(_Compare(), allocator_type())
{_M_t.insert_equal(__first, __last); }

template <class _InputIterator>
multiset(_InputIterator __first, _InputIterator __last,
const _Compare& __comp,
const allocator_type& __a = allocator_type())
:_M_t(__comp, __a) { _M_t.insert_equal(__first, __last); }

#else

multiset(const value_type* __first, const value_type* __last)
:_M_t(_Compare(), allocator_type())
{_M_t.insert_equal(__first, __last); }

multiset(const value_type* __first, const value_type* __last,
const _Compare& __comp,
const allocator_type& __a = allocator_type())
:_M_t(__comp, __a) { _M_t.insert_equal(__first, __last); }

multiset(const_iterator __first, const_iterator __last)
:_M_t(_Compare(), allocator_type())
{_M_t.insert_equal(__first, __last); }

multiset(const_iterator __first, const_iterator __last,
const _Compare& __comp,
const allocator_type& __a = allocator_type())
:_M_t(__comp, __a) { _M_t.insert_equal(__first, __last); }

#endif /* __STL_MEMBER_TEMPLATES */

multiset(constmultiset<_Key,_Compare,_Alloc>& __x) : _M_t(__x._M_t) {}
multiset<_Key,_Compare,_Alloc>&
operator=(const multiset<_Key,_Compare,_Alloc>& __x) {
_M_t = __x._M_t;//调用了底层红黑树的operator=操作函数
return *this;
}

//以下所有的multiset操作行为，RB-tree都已提供，所以multiset只要调用即可
//accessors:

//返回用于key比较的函数,调用RB-Tree的key_comp()
key_compare key_comp() const { return _M_t.key_comp(); }
//由于multiset的性质, value和key使用同一个比较函数
value_compare value_comp() const { return _M_t.key_comp(); }
allocator_type get_allocator() const { return _M_t.get_allocator(); }

iterator begin() const { return _M_t.begin(); }
iterator end() const { return _M_t.end(); }
reverse_iterator rbegin() const { return _M_t.rbegin(); }
reverse_iterator rend() const { return _M_t.rend(); }
bool empty() const { return _M_t.empty(); }
size_type size() const { return _M_t.size(); }
size_type max_size() const { return _M_t.max_size(); }
//这里调用的swap()函数是专属于RB-Tree的swap()，并不是STL的swap()算法
void swap(multiset<_Key,_Compare,_Alloc>& __x) {_M_t.swap(__x._M_t); }

//insert/erase
/*
插入节点
iteratorinsert (const value_type& val);

iteratorinsert (iterator position, const value_type& val);

template<class InputIterator>
voidinsert (InputIterator first, InputIterator last);
*/
//插入数据节点
iterator insert(const value_type& __x) {
return _M_t.insert_equal(__x);
}
//在指定位置插入节点
iterator insert(iterator __position, const value_type& __x) {
typedef typename _Rep_type::iterator _Rep_iterator;
return _M_t.insert_equal((_Rep_iterator&)__position, __x);
}

#ifdef __STL_MEMBER_TEMPLATES
template <class _InputIterator>
void insert(_InputIterator __first, _InputIterator __last) {
_M_t.insert_equal(__first, __last);
}
#else
void insert(const value_type* __first, const value_type* __last) {
_M_t.insert_equal(__first, __last);
}
void insert(const_iterator __first, const_iterator __last) {
_M_t.insert_equal(__first, __last);
}
#endif /* __STL_MEMBER_TEMPLATES */
//擦除指定位置的元素
void erase(iterator __position) {
typedef typename _Rep_type::iterator _Rep_iterator;
_M_t.erase((_Rep_iterator&)__position);
}
//擦除元素值为x的节点
size_type erase(const key_type& __x) {
return _M_t.erase(__x);
}
//擦除指定区间的节点
void erase(iterator __first, iterator __last) {
typedef typename _Rep_type::iterator _Rep_iterator;
_M_t.erase((_Rep_iterator&)__first, (_Rep_iterator&)__last);
}
//清除multiset
void clear() { _M_t.clear(); }

//multiset operations:

//查找元素值为x的节点
iterator find(const key_type& __x) const { return _M_t.find(__x); }
//返回指定元素的个数
size_type count(const key_type& __x) const { return _M_t.count(__x);}
//Returns an iterator pointing to the first element in the container
//whose key is not considered to go before k (i.e., either it isequivalent or goes after).
iterator lower_bound(const key_type& __x) const {
return _M_t.lower_bound(__x);
}
//Returns an iterator pointing to the first element that is greater thankey.
iterator upper_bound(const key_type& __x) const {
return _M_t.upper_bound(__x);
}
//Returns the bounds of a range that includes all the elements in thecontainer
//which have a key equivalent to k
//Because the elements in a map container have unique keys,
//the range returned will contain a single element at most.
pair<iterator,iterator> equal_range(const key_type& __x) const{
return _M_t.equal_range(__x);
}

//以下是操作符的重载

#ifdef __STL_TEMPLATE_FRIENDS
template <class _K1, class _C1, class _A1>
friend bool operator== (const multiset<_K1,_C1,_A1>&,
constmultiset<_K1,_C1,_A1>&);
template <class _K1, class _C1, class _A1>
friend bool operator< (const multiset<_K1,_C1,_A1>&,
constmultiset<_K1,_C1,_A1>&);
#else /* __STL_TEMPLATE_FRIENDS */
friend bool __STD_QUALIFIER
operator== __STL_NULL_TMPL_ARGS (const multiset&, constmultiset&);
friend bool __STD_QUALIFIER
operator< __STL_NULL_TMPL_ARGS (const multiset&, constmultiset&);
#endif /* __STL_TEMPLATE_FRIENDS */
};

template <class _Key, class _Compare,class _Alloc>
inline bool operator==(constmultiset<_Key,_Compare,_Alloc>& __x,
constmultiset<_Key,_Compare,_Alloc>& __y) {
return __x._M_t == __y._M_t;
}

template <class _Key, class _Compare,class _Alloc>
inline bool operator<(constmultiset<_Key,_Compare,_Alloc>& __x,
const multiset<_Key,_Compare,_Alloc>&__y) {
return __x._M_t < __y._M_t;
}

#ifdef __STL_FUNCTION_TMPL_PARTIAL_ORDER

template <class _Key, class _Compare,class _Alloc>
inline bool operator!=(constmultiset<_Key,_Compare,_Alloc>& __x,
constmultiset<_Key,_Compare,_Alloc>& __y) {
return !(__x == __y);
}

template <class _Key, class _Compare,class _Alloc>
inline bool operator>(constmultiset<_Key,_Compare,_Alloc>& __x,
const multiset<_Key,_Compare,_Alloc>&__y) {
return __y < __x;
}

template <class _Key, class _Compare,class _Alloc>
inline bool operator<=(constmultiset<_Key,_Compare,_Alloc>& __x,
constmultiset<_Key,_Compare,_Alloc>& __y) {
return !(__y < __x);
}

template <class _Key, class _Compare,class _Alloc>
inline bool operator>=(constmultiset<_Key,_Compare,_Alloc>& __x,
constmultiset<_Key,_Compare,_Alloc>& __y) {
return !(__x < __y);
}

template <class _Key, class _Compare, class_Alloc>
inline voidswap(multiset<_Key,_Compare,_Alloc>& __x,
multiset<_Key,_Compare,_Alloc>& __y) {
__x.swap(__y);
}

#endif /* __STL_FUNCTION_TMPL_PARTIAL_ORDER*/

#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_MULTISET_H */

// Local Variables:
// mode:C++
// End: