STL学习（自学手册+源码分析）之 map multimap

1.1 map

1.1.1 map主体实现

#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;
  typedef T data_type;
  typedef T mapped_type;
  typedef pair<const Key, T> value_type;//数据类型是pair封装起来的 注意key被封装成const的,即不允许修改key类型
  typedef Compare key_compare;
    
  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);
    }
  };

private:
//底层实现还是使用的红黑树
  typedef rb_tree<key_type, value_type, 
                  select1st<value_type>, key_compare, Alloc> rep_type;
  rep_type t;  // red-black tree representing map
public:
//这里的迭代器实现的就是红黑树的迭代器
  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;
  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) {}

#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;
    return *this; 
  }

  // 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&);
};

特别注意map重载的operator[]，，这里如果key不存在，则会创建一个新的key值。

T& operator[](const key_type& k) {
    return (*((insert(value_type(k, T()))).first)).second;
  }

1.2 multimap

1.2.1 multimap主体实现

#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 multimap {
public:

// typedefs:

  typedef Key key_type;
  typedef T data_type;
  typedef T mapped_type;
  typedef pair<const Key, T> value_type;
  typedef Compare key_compare;

  class value_compare : public binary_function<value_type, value_type, bool> {
  friend class multimap<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);
    }
  };

private:
  typedef rb_tree<key_type, value_type, 
                  select1st<value_type>, key_compare, Alloc> rep_type;
  rep_type t;  // red-black tree representing multimap
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;
  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

  multimap() : t(Compare()) { }
  explicit multimap(const Compare& comp) : t(comp) { }

#ifdef __STL_MEMBER_TEMPLATES  
  template <class InputIterator>
  multimap(InputIterator first, InputIterator last)
    : t(Compare()) { t.insert_equal(first, last); }

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

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

  multimap(const multimap<Key, T, Compare, Alloc>& x) : t(x.t) { }
  multimap<Key, T, Compare, Alloc>&
  operator=(const multimap<Key, T, Compare, Alloc>& x) {
    t = x.t;
    return *this; 
  }

  // 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(); }
  void swap(multimap<Key, T, Compare, Alloc>& x) { t.swap(x.t); }

  // insert/erase

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

  // multimap 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 multimap&,
                                               const multimap&);
  friend bool operator< __STL_NULL_TMPL_ARGS (const multimap&,
                                              const multimap&);
};