LinkedMap的C++實現

Linkedmap的C++實現

     在網上找了半天，沒有找到能夠按照插入順序迭代輸出的map容器，所以自己按照java語言中Linkedmap的基本原理用C++實現了一個簡單的Linkedmap，結合了list容器的迭代特性和map容器的查詢效率等優點，有不足之處還望指正。

代碼：

//
// Linked_map.h
// --------------------
// Map 容器和鏈表的結合，實現按照插入順序排序輸出
//
// @author：zxinxiang
// @time：  2015.04.28
//

#ifndef __LINKED_MAP_H__
#define __LINKED_MAP_H__

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#pragma warning(disable: 4786)
#pragma warning(disable: 4503)

#include <map>
#include <list>
#include <assert.h>

class noncopyable
{
protected:
	noncopyable() {}
	~noncopyable() {}
private:
	noncopyable(const noncopyable&);
	const noncopyable& operator=(const noncopyable&);
};


// Note: assumes K and V are POD types.
template <typename K, typename V>
class Linked_map : private noncopyable
{
public:
	// The type of a value in the map.
	typedef std::pair<K, V> value_type;
	
	// The type of a non-const iterator over the map.
	typedef typename std::list<value_type>::iterator iterator;
	
	// The type of a const iterator over the map.
	typedef typename std::list<value_type>::const_iterator const_iterator;

	typedef typename std::map<K, iterator>::iterator pIterator;
	
	// Constructor.
	Linked_map()
		: sizes_(0)
	{
	}
	
	// Destructor.
	~Linked_map()
	{
	}
	
	// Get an iterator for the beginning of the map.
	iterator begin()
	{
		return values_.begin();
	}
	
	// Get an iterator for the beginning of the map.
	const_iterator begin() const
	{
		return values_.begin();
	}
	
	// Get an iterator for the end of the map.
	iterator end()
	{
		return values_.end();
	}
	
	// Get an iterator for the end of the map.
	const_iterator end() const
	{
		return values_.end();
	}
	
	// Check whether the map is empty.
	bool empty() const
	{
		return values_.empty();
	}
	
	// Find an entry in the map.
	iterator find(const K& k)
	{
		if (sizes_ > 0)
		{
			pIterator it = mappeds_.find(k);
			if (it == mappeds_.end())
				return values_.end();
			iterator find_it = it->second;
			return find_it;
		}
		return values_.end();
	}
	
	// Find an entry in the map.
	const_iterator find(const K& k) const
	{
		if (sizes_ > 0)
		{
			pIterator it = mappeds_.find(k);
			if (it == mappeds_.end())
				return values_.end();
			const_iterator find_it = it->second;
			return find_it;
		}
		return values_.end();
	}
	
	// Insert a new entry into the map.
	std::pair<iterator, bool> insert(const value_type& v)
	{
		pIterator pIt = mappeds_.find(v.first);
		if (pIt == mappeds_.end())
		{
			values_.push_back(v);
			mappeds_.insert(pair<K, iterator>(v.first, --values_.end()));
			++sizes_;
		}
		else
		{
			values_.erase(pIt->second);
			values_.push_back(v);
			pIt->second = --values_.end();
		}
		return std::pair<iterator, bool>(--values_.end(), true);
	}

	// Insert an element value to the list of the specified location.
	iterator insert(iterator it, const value_type& v)
	{
		pIterator pIt = mappeds_.find(v.first);
		if(pIt != mappeds_.end())
		{
			values_.erase(pIt->second);
			--sizes_;
		}
		iterator _it = values_.insert(it, v);
		mappeds_.insert(pair<K, iterator>(v.first, _it));
		++sizes_;
		return _it;
	}
	
	// Erase an entry from the map.
	void erase(iterator it)
	{
		assert(it != values_.end());
		assert(sizes_ != 0);

		value_type v = *it;
		values_.erase(it);
		mappeds_.erase(v.first);
		--sizes_;
	}
	
	// Erase a key from the map.
	void erase(const K& k)
	{
		iterator it = find(k);
		if (it != values_.end())
			erase(it);
	}
	
	// Remove all entries from the map.
	void clear()
	{
		// Clear the values.
		values_.clear();
		mappeds_.clear();
		sizes_ = 0;
	}
	
	// Calculate the number of elements.
	size_t size()
	{
		return sizes_;
	}

private:
	// The number of elements in the map.
	size_t sizes_;
	
	// The list of all values in the map.
	std::list<value_type> values_;
	
	// The map of list nodes.
	std::map<K, iterator> mappeds_;
};


#endif // __LINKED_MAP_H__

Test測試代碼：

#include <iostream>
#include <string>
#include <ctime>

#include "Linked_map.h"
using namespace std;

int main(int argc, char** argv)
{
    //測試效率
    clock_t start = clock(); 
    Linked_map<int,string> myMap;
    for(int i = 0; i < 1000000; i++)
    {
        //插入節點
        myMap.insert(pair<int,string>(i, "hello linked map!"));
    }
    clock_t end = clock();  
    cout << "Test my LinkedMap: \n"; 
    //調用了time.h文件的CLOCKS_PER_SEC，表示每過千分之一秒，clock()函數返回值加1
    cout << "插入1百萬 條數據耗時： "  
	<< double(end - start) / CLOCKS_PER_SEC << " 秒" << endl;
	
    //測試map效率
    start = clock();
    map<int,string> stlmap;
    for(int j = 0; j < 1000000; j++)
    {
        //插入節點
        stlmap.insert(pair<int,string>(j,"hello map!"));
    }
    end = clock();  
    cout << "Test STL Map: \n";  
    //調用了time.h文件的CLOCKS_PER_SEC，表示每過千分之一秒，clock()函數返回值加1  
    cout << "插入1百萬 條數據耗時： "  
         << double(end - start) / CLOCKS_PER_SEC << " 秒" << endl; 

    return 0;
}

 

測試結果：