SET是STL中的标准容器,SET里面的元素会根据键值自动排序,它不像map那样拥有实值value和键值key的对应,set只有实值。SET的底层实现时RB-tree,当插入到RB-tree中后,其值不能再更改,因为更改就意味着可能不符合RB-tree的特性了,所以其迭代器set<T>::iterator是RB-tree的constrant iterator。由于SET底层是RB-tree,所以SET在插入等操作之后,迭代器不会失效,但删除元素的迭代器是个例外。
G++ 2.91.57,cygnus\cygwin-b20\include\g++\stl_set.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_SET_H #define __SGI_STL_INTERNAL_SET_H __STL_BEGIN_NAMESPACE #if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32) #pragma set woff 1174 #endif //less<Key>说明默认使用递增排序 #ifndef __STL_LIMITED_DEFAULT_TEMPLATES template <class Key, class Compare = less<Key>, class Alloc = alloc> #else template <class Key, class Compare, class Alloc = alloc> #endif class set { public: // typedefs: //key_type和 value_type类型都是实值 typedef Key key_type; typedef Key value_type; // 注意,以下 key_compare 和 value_compare 使用相同的比较函数 typedef Compare key_compare; typedef Compare value_compare; private: /* 注意,identity 定义于 <stl_function.h>,参考第7章,其定义为: template <class T> struct identity : public unary_function<T, T> { const T& operator()(const T& x) const { return x; } }; */ // 以下,rb_tree<Key, Value, KeyOfValue, Compare, Alloc> typedef rb_tree<key_type, value_type, identity<value_type>, key_compare, Alloc> rep_type; rep_type t; // 底层采用红黑树 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; //用的是RB-tree的 const_iterator。不允许修改其值,也不允许使用者在任意处插入元素 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_iterator const_reverse_iterator; typedef typename rep_type::size_type size_type; typedef typename rep_type::difference_type difference_type; // allocation/deallocation // 注意, set 一定使用 insert_unique() 而不使用 insert_equal()。 // multiset 才使用 insert_equal()。 set() : t(Compare()) {} explicit set(const Compare& comp) : t(comp) {} //初始化SET #ifdef __STL_MEMBER_TEMPLATES template <class InputIterator> set(InputIterator first, InputIterator last) : t(Compare()) { t.insert_unique(first, last); } template <class InputIterator> set(InputIterator first, InputIterator last, const Compare& comp) : t(comp) { t.insert_unique(first, last); } #else set(const value_type* first, const value_type* last) : t(Compare()) { t.insert_unique(first, last); } set(const value_type* first, const value_type* last, const Compare& comp) : t(comp) { t.insert_unique(first, last); } set(const_iterator first, const_iterator last) : t(Compare()) { t.insert_unique(first, last); } set(const_iterator first, const_iterator last, const Compare& comp) : t(comp) { t.insert_unique(first, last); } #endif /* __STL_MEMBER_TEMPLATES */ set(const set<Key, Compare, Alloc>& x) : t(x.t) {} set<Key, Compare, Alloc>& operator=(const set<Key, Compare, Alloc>& x) { t = x.t; return *this; } //一下所有的SET操作,RB-tree都已经提供,SET只是调用而已 // accessors: key_compare key_comp() const { return t.key_comp(); } // 以下注意,set 的value_comp() 实际上就是RB-tree 的key_comp()。 value_compare value_comp() const { return t.key_comp(); } iterator begin() const { return t.begin(); } iterator end() const { return t.end(); } reverse_iterator rbegin() const { return t.rbegin(); } reverse_iterator rend() const { return t.rend(); } bool empty() const { return t.empty(); } size_type size() const { return t.size(); } size_type max_size() const { return t.max_size(); } void swap(set<Key, Compare, Alloc>& x) { t.swap(x.t); } // insert/erase typedef pair<iterator, bool> pair_iterator_bool; pair<iterator,bool> insert(const value_type& x) { pair<typename rep_type::iterator, bool> p = t.insert_unique(x); return pair<iterator, bool>(p.first, p.second); } iterator insert(iterator position, const value_type& x) { typedef typename rep_type::iterator rep_iterator; return t.insert_unique((rep_iterator&)position, x); } #ifdef __STL_MEMBER_TEMPLATES template <class InputIterator> void insert(InputIterator first, InputIterator last) { t.insert_unique(first, last); } #else void insert(const_iterator first, const_iterator last) { t.insert_unique(first, last); } void insert(const value_type* first, const value_type* last) { t.insert_unique(first, last); } #endif /* __STL_MEMBER_TEMPLATES */ void erase(iterator position) { typedef typename rep_type::iterator rep_iterator; t.erase((rep_iterator&)position); } size_type erase(const key_type& x) { return t.erase(x); } void erase(iterator first, iterator last) { typedef typename rep_type::iterator rep_iterator; t.erase((rep_iterator&)first, (rep_iterator&)last); } void clear() { t.clear(); } // set operations: //使用的是RB-tree的搜索函数,而不是STL的find,STL的find的只是 //循序搜索,效率不如关联容器自己定义的效率高 iterator find(const key_type& x) const { return t.find(x); } size_type count(const key_type& x) const { return t.count(x); } iterator lower_bound(const key_type& x) const { return t.lower_bound(x); } iterator upper_bound(const key_type& x) const { return t.upper_bound(x); } pair<iterator,iterator> equal_range(const key_type& x) const { return t.equal_range(x); } friend bool operator== __STL_NULL_TMPL_ARGS (const set&, const set&); friend bool operator< __STL_NULL_TMPL_ARGS (const set&, const set&); }; template <class Key, class Compare, class Alloc> inline bool operator==(const set<Key, Compare, Alloc>& x, const set<Key, Compare, Alloc>& y) { return x.t == y.t; } template <class Key, class Compare, class Alloc> inline bool operator<(const set<Key, Compare, Alloc>& x, const set<Key, Compare, Alloc>& y) { return x.t < y.t; } #ifdef __STL_FUNCTION_TMPL_PARTIAL_ORDER template <class Key, class Compare, class Alloc> inline void swap(set<Key, Compare, Alloc>& x, set<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 #endif __STL_END_NAMESPACE #endif /* __SGI_STL_INTERNAL_SET_H */ // Local Variables: // mode:C++ // End:
《STL源码剖析》---stl_set.h阅读笔记
时间: 2024-10-27 17:53:56