STL源码剖析 容器 stl_map.h

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map

struct ltstr
{
  bool operator()(const char* s1, const char* s2) const
  {
    return strcmp(s1, s2) < 0;
  }
};


int main()
{
  map<const char*, int, ltstr> months;
  
  months["january"] = 31; //这里调用了两个函数, 先调用 map 的operator[] 函数返回键值对应实值的引用， 再调用该实值类型的 operator= 函数进行赋值
  months["february"] = 28;
  months["march"] = 31;
  months["april"] = 30;
  months["may"] = 31;
  months["june"] = 30;
  months["july"] = 31;
  months["august"] = 31;
  months["september"] = 30;
  months["october"] = 31;
  months["november"] = 30;
  months["december"] = 31;
  
  cout << "june -> " << months["june"] << endl;
  map<const char*, int, ltstr>::iterator cur  = months.find("june");
  map<const char*, int, ltstr>::iterator prev = cur;
  map<const char*, int, ltstr>::iterator next = cur;    
  ++next;
  --prev;
  cout << "Previous (in alphabetical order) is " << (*prev).first << endl;
  cout << "Next (in alphabetical order) is " << (*next).first << endl;
}

//stl_pair.h里 pair 的定义
template <class T1, class T2>
struct pair {
  typedef T1 first_type;
  typedef T2 second_type;


  T1 first;
  T2 second;
  pair() : first(T1()), second(T2()) {}
  pair(const T1& a, const T2& b) : first(a), second(b) {}


#ifdef __STL_MEMBER_TEMPLATES
  template <class U1, class U2>
  pair(const pair<U1, U2>& p) : first(p.first), second(p.second) {}
#endif
};

//stl_map.h 源码
#ifndef __SGI_STL_INTERNAL_MAP_H
#define __SGI_STL_INTERNAL_MAP_H


__STL_BEGIN_NAMESPACE


#if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)
#pragma set woff 1174
#endif


#ifndef __STL_LIMITED_DEFAULT_TEMPLATES
template <class Key, class T, class Compare = less<Key>, class Alloc = alloc>
#else
template <class Key, class T, class Compare, class Alloc = alloc>
#endif
class map {
public:


// typedefs:


  typedef Key key_type;  //键值类型
  typedef T data_type;   //数值类型
  typedef T mapped_type;
  typedef pair<const Key, T> value_type; //元素类型(键值/实值)
  typedef Compare key_compare; //键值比较函数
    
  // functor， 其作用是调用 "元素比较函数"	
  class value_compare
    : public binary_function<value_type, value_type, bool> {
  friend class map<Key, T, Compare, Alloc>;
  protected :
    Compare comp;
    value_compare(Compare c) : comp(c) {}
  public:
    bool operator()(const value_type& x, const value_type& y) const {
      return comp(x.first, y.first); //以 x, y 的键值调用了键值比较函数
    }
  };


private:
  typedef rb_tree<key_type, value_type, 
                  select1st<value_type>, key_compare, Alloc> rep_type;
  rep_type t;  // 以红黑树表现 map
public:
  typedef typename rep_type::pointer pointer;
  typedef typename rep_type::const_pointer const_pointer;
  typedef typename rep_type::reference reference;
  typedef typename rep_type::const_reference const_reference;
  //set 的 iterator 定义为 const ，因为它不允许改变 set 里的值
  //map 的 iterator 不定义为 const，因为它虽不允许改变键值，但允许改变实值
  typedef typename rep_type::iterator iterator;
  typedef typename rep_type::const_iterator const_iterator;
  typedef typename rep_type::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


  map() : t(Compare()) {}
  explicit map(const Compare& comp) : t(comp) {}// 传递 Compare() 产生的函数对象给底层的红黑树作为初始化时设定的比较函数


  //不允许键值重复，所以只能使用 RB-tree 的 insert_unique()
#ifdef __STL_MEMBER_TEMPLATES
  template <class InputIterator>
  map(InputIterator first, InputIterator last)
    : t(Compare()) { t.insert_unique(first, last); }


  template <class InputIterator>
  map(InputIterator first, InputIterator last, const Compare& comp)
    : t(comp) { t.insert_unique(first, last); }
#else
  map(const value_type* first, const value_type* last)
    : t(Compare()) { t.insert_unique(first, last); }
  map(const value_type* first, const value_type* last, const Compare& comp)
    : t(comp) { t.insert_unique(first, last); }


  map(const_iterator first, const_iterator last)
    : t(Compare()) { t.insert_unique(first, last); }
  map(const_iterator first, const_iterator last, const Compare& comp)
    : t(comp) { t.insert_unique(first, last); }
#endif /* __STL_MEMBER_TEMPLATES */


  map(const map<Key, T, Compare, Alloc>& x) : t(x.t) {}
  map<Key, T, Compare, Alloc>& operator=(const map<Key, T, Compare, Alloc>& x)
  {
    t = x.t;  // 调用了底层红黑树的 operator= 函数
    return *this; 
  }


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


  key_compare key_comp() const { return t.key_comp(); }
  value_compare value_comp() const { return value_compare(t.key_comp()); }
  iterator begin() { return t.begin(); }
  const_iterator begin() const { return t.begin(); }
  iterator end() { return t.end(); }
  const_iterator end() const { return t.end(); }
  reverse_iterator rbegin() { return t.rbegin(); }
  const_reverse_iterator rbegin() const { return t.rbegin(); }
  reverse_iterator rend() { return t.rend(); }
  const_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(); }
  T& operator[](const key_type& k) {
    return (*((insert(value_type(k, T()))).first)).second;
  }
  void swap(map<Key, T, Compare, Alloc>& x) { t.swap(x.t); }


  // insert/erase


  pair<iterator,bool> insert(const value_type& x) { return t.insert_unique(x); }
  iterator insert(iterator position, const value_type& x) {
    return t.insert_unique(position, x);
  }
#ifdef __STL_MEMBER_TEMPLATES
  template <class InputIterator>
  void insert(InputIterator first, InputIterator last) {
    t.insert_unique(first, last);
  }
#else
  void insert(const value_type* first, const value_type* last) {
    t.insert_unique(first, last);
  }
  void insert(const_iterator first, const_iterator last) {
    t.insert_unique(first, last);
  }
#endif /* __STL_MEMBER_TEMPLATES */


  void erase(iterator position) { t.erase(position); }
  size_type erase(const key_type& x) { return t.erase(x); }
  void erase(iterator first, iterator last) { t.erase(first, last); }
  void clear() { t.clear(); }


  // map operations:


  iterator find(const key_type& x) { return t.find(x); }
  const_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) {return t.lower_bound(x); }
  const_iterator lower_bound(const key_type& x) const {
    return t.lower_bound(x); 
  }
  iterator upper_bound(const key_type& x) {return t.upper_bound(x); }
  const_iterator upper_bound(const key_type& x) const {
    return t.upper_bound(x); 
  }
  
  pair<iterator,iterator> equal_range(const key_type& x) {
    return t.equal_range(x);
  }
  pair<const_iterator,const_iterator> equal_range(const key_type& x) const {
    return t.equal_range(x);
  }
  friend bool operator== __STL_NULL_TMPL_ARGS (const map&, const map&);
  friend bool operator< __STL_NULL_TMPL_ARGS (const map&, const map&);
};


template <class Key, class T, class Compare, class Alloc>
inline bool operator==(const map<Key, T, Compare, Alloc>& x, 
                       const map<Key, T, Compare, Alloc>& y) {
  return x.t == y.t;
}


template <class Key, class T, class Compare, class Alloc>
inline bool operator<(const map<Key, T, Compare, Alloc>& x, 
                      const map<Key, T, Compare, Alloc>& y) {
  return x.t < y.t;
}


#ifdef __STL_FUNCTION_TMPL_PARTIAL_ORDER


template <class Key, class T, class Compare, class Alloc>
inline void swap(map<Key, T, Compare, Alloc>& x, 
                 map<Key, T, 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_MAP_H */


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

STL源码剖析 容器 stl_map.h,布布扣,bubuko.com

STL源码剖析 容器 stl_map.h

标签：style   blog   http   color   使用   os   

原文地址：http://blog.csdn.net/zhengsenlie/article/details/38045119