STL笔记之multimap

multimap的特性和map完全相同，唯一的差别在于它允许键值重复，因此它的插入操作采用的是底层机制RBtree的insert_equal()而非insert_unique()。

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) :firsr(a), second(b) {}
};

template<class Key, class T,
	class Compare = less<Key>,
	class Alloc = alloc>
	class multimap
{
	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,
		selectlst<value_type>, key_compare, Alloc> rep_type;
	rep_type t;
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;

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

	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);
	}

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

	key_compare key_comp()const { return t.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(); }

	T& operator[](const key_type& k) {
		return (*((insert(value_type(k, T()))).first)).second;
	}
	void swap(multimap<Key, T, Compare, Alloc>& x) { t.swap(x.t); }

	pair<iterator, bool> insert(const value_type& x) {
		return t.insert_equal(x);
	}
	iterator insert(iterator position, const value_type& x) {
		return t.insert_equal(position, x);
	}
	template<class InputIterator>
	void insert(InputIterator first, InputIterator last) {
		t.insert_equal(first, last);
	}

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

	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&);

};

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

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