C++实现类似python中list, dict的结构

前言

公司某段业务需要将python代码移植到c++, 其中多数情况下, 只需简单的更改词法和语法即可, 直到我遇到如下场景:

  1. 初始化时使用大量数据, 且会做多次数据拼接. 有时数据中还会混入不同的类型

    在python中, 这一需求可使用list轻松地实现, 但c++中就xx了..

  2. 大量使用dict, 且value中的数据类型不统一.

这些情况下, 如果不做些封装处理, 代码将变得非常难看. 经过查阅资料, 发现boost库中有一个类非常适合这种场景:boost::any, 遂开干.

实现

首先需要安装boost,我使用vcpkg安装的, 亦可直接到[官网][https://www.boost.org/0]下载, 参考https://zhuanlan.zhihu.com/p/235157113

  1. 安装vcpkg

    git clone https://github.com/microsoft/vcpkg
vcpkg\bootstrap-vcpkg.bat
vcpkg\vcpkg integrate install

  2. 安装boost(比较慢,须耐心等待)

    vcpkg\vcpkg install boost

  3. 实现Elem.hpp

    #pragma once

#include
#include
#include 
#include 
#include 


using namespace std;
using boost::any;

union ListElement
{
	unsigned char byte;
	unsigned short word;
	unsigned int dword;
	unsigned long long qword;
	float f;
	double d;
};

class Elem
{
public:
	Elem() = default;
	template
	Elem(const ValueType& value)
	{
		this->data = value;
	}

	Elem(const Elem& other)
	{
		this->data = other.data;
	}
	bool operator==(bool value)
	{
		return ((bool)toByte()) == value;
	}

	bool operator==(char value)
	{
		return toByte() == value;
	}
	bool operator==(unsigned char value)
	{
		return toByte() == value;
	}
	bool operator==(short value)
	{
		return toInt16() == value;
	}
	bool operator==(unsigned short value)
	{
		return toInt16() == value;
	}
	bool operator==(int value)
	{
		return toInt32() == value;
	}
	bool operator==(unsigned int value)
	{
		return toInt32() == value;
	}

	Elem operator=(const Elem& e)
	{
		this->data = e.data;
		return this->data;
	}

	/*static Elem operator+(const Elem& left ,const Elem& right)
	{
		if (left.type() == typeid(int))
			return this->data + e.toInt32();
	}*/

	unsigned char toByte()
	{
		ListElement e = this->convert();
		return e.byte;
	}
	short toInt16()
	{
		ListElement e = this->convert();
		return e.word;
	}
	int toInt32()
	{
		ListElement e = this->convert();
		return e.dword;
	}
	long long toInt64()
	{
		ListElement e = this->convert();
		return e.qword;
	}
	float toFloat()
	{
		ListElement e = this->convert();
		return e.f;
	}
	double toDouble()
	{
		ListElement e = this->convert();
		return e.d;
	}
	string toString()
	{
		if (this->isType())
			return  "\""+this->cast()+ "\"";
		else if (this->isType())
			return  "\""+string(this->cast())+ "\"";
		else if (this->isType())
			return "\""+string(this->cast())+"\"";
		else if (this->isType())
			return this->cast() ? "true" : "false";
		else if (this->isType() || this->isType())
			return to_string(this->toByte());
		else if (this->isType() || this->isType())
			return to_string(this->toInt16());
		else if (this->isType() || this->isType())
			return to_string(this->toInt32());
		else if (this->isType() || this->isType())
			return to_string(this->toInt32());
		else if (this->isType() || this->isType())
			return to_string(this->toInt64());
		else if (this->isType())
			return to_string(this->toFloat());
		else if (this->isType())
			return to_string(this->toDouble());
		else
			return string("undefined");
	}

	template
	T cast() {
		if (this->data.type() != typeid(T)) throw exception(("data type:"+string(this->data.type().name())+" is not "+string(typeid(T).name())).c_str());
		T result = boost::any_cast(this->data);
		return result;

	}
	const boost::typeindex::type_info& type()
	{
		return this->data.type();
	}

	template
	bool isType()
	{
		if (this->empty()) return false;
		return this->data.type() == typeid(T);
	}

	bool empty() {
		return this->data.empty();
	}
private:
	ListElement convert()
	{
		ListElement e{ 0 };
		if (this->data.type() == typeid(unsigned char))
			e.byte = boost::any_cast(this->data);

		else if (this->data.type() == typeid(char))
			e.byte = boost::any_cast(this->data);

		else if (this->data.type() == typeid(short))
			e.word = boost::any_cast(this->data);

		else if (this->data.type() == typeid(unsigned short))
			e.word = boost::any_cast(this->data);

		else if (this->data.type() == typeid(int))
			e.dword = boost::any_cast(this->data);

		else if (this->data.type() == typeid(unsigned int))
			e.dword = boost::any_cast(this->data);

		else if (this->data.type() == typeid(long))
			e.dword = boost::any_cast(this->data);

		else if (this->data.type() == typeid(unsigned long))
			e.dword = boost::any_cast(this->data);

		else if (this->data.type() == typeid(long long))
			e.qword = boost::any_cast(this->data);

		else if (this->data.type() == typeid(unsigned long long))
			e.qword = boost::any_cast(this->data);

		else if (this->data.type() == typeid(float))
			e.f = boost::any_cast(this->data);

		else if (this->data.type() == typeid(double))
			e.d = boost::any_cast(this->data);
		else
		{
			string name = this->data.type().name();
			throw std::exception(("data type " + name + " is not supported").c_str());
		}
		return e;
	}
private:
	any data;
};

  4. 实现List.hpp

    #pragma once


#include
#include
#include 
#include "Elem.hpp"

using namespace std;


class List
{
public:
	List() = default;
	List(const List& list, bool isRestruct = true)
	{
		if (isRestruct)
		{
			for (int i = 0; i < list.data.size(); i++)
			{
				this->data.push_back(list.data[i]);
			}
			return;
		}
		this->data.push_back(list);
	}
	List(const string& str)
	{
		for (int i = 0; i < str.size(); i++)
		{
			this->data.push_back((unsigned char)str[i]);
		}
	}



	/* 其实现必须在头文件,否则会找不到符号 */
	template
	List(Arg... args)
	{
		append(args...);
	}

	template
	void append(T value)
	{
		data.push_back(value);
	}


	template 
	void append(Head head, Rail... last)
	{
		data.push_back(head);
		append(last...);
	}


	List operator+(const int i)
	{
		this->data.push_back(i);
		return this;
	}
	List operator+(const List& list)
	{
		List tempList;
		for (int i = 0; i < this->data.size(); i++)
		{
			tempList.data.push_back(this->data[i]);
		}
		for (int i = 0; i < list.data.size(); i++)
		{
			tempList.data.push_back(list.data[i]);
		}
		return tempList;
	}

	List operator=(const List& list)
	{
		this->data.clear();
		for (int i = 0; i < list.data.size(); i++)
		{
			this->data.push_back(list.data[i]);
		}
		return this;
	}


	List operator+=(const string& str)
	{
		for (int i = 0; i < str.size(); i++)
		{
			this->data.push_back(str[i]);
		}
		return this;
	}
	List operator+=(const List& list)
	{
		for (int i = 0; i < list.data.size(); i++)
		{
			this->data.push_back(list.data[i]);
		}
		return this;
	}
	List operator+=(unsigned char c)
	{
		this->data.push_back(c);
		return this;
	}

	Elem& operator[](int index)
	{
		return data[index];
	}

	void set(int index, Elem a)
	{
		this->data[index] = a;
	}
	Elem get(int index)
	{
		return this->data[index];
	}

	void foreach(void(*callback)(Elem&))
	{
		for (int i = 0; i < this->data.size(); i++)
		{
			callback(this->data[i]);
		}
	}

	string toByteString()
	{
		string str;
		for (int i = 0; i < this->data.size(); i++)
		{
			str += this->data[i].toByte();
		}
		if (str.size() != this->data.size()) throw exception(("List to string failed,"+to_string(this->data.size() - str.size())+" byte(s) are missing").c_str());
		return str;
	}
	int size()
	{
		return this->data.size();
	}

	bool empty()
	{
		return this->data.size() == 0;
	}
	bool exist(int index)
	{
		if (this->data.size() >= index && !this->data[index].empty())
		{
			return true;
		}
		return false;
	}
	static void fromJson(string jsonValue) {

	}
	string toIntArray()
	{
		string intArray;
		for (auto i = 0; i < this->data.size() - 1; i++)
		{
			intArray += to_string((unsigned int)data[i].toByte()) + ", ";
		}
		intArray += to_string((unsigned int)data[this->data.size() - 1].toByte());
		return intArray;
	}
	string toStringArray()
	{
		string array = "[";
		for (auto i = 0; i < this->data.size(); i++)
		{
			array += data[i].toString()+ (i==(this->data.size()-1)? "":",");
		}
		array += "]";
		return array;
	}

private:
	vector  data;
};

  5. 实现Dict.hpp

    #pragma once


#include
#include
#include 
#include "Elem.hpp"


using namespace std;



class Dict
{
public:
	Dict() = default;
	Dict(const Dict& dict)
	{
		this->update(const_cast(dict));
	}
	Dict(pair)
	{

	}

	Elem& operator[](const Elem& key)
	{
		string strKey;
		Elem& e = const_cast(key);
		string name = e.type().name();
		if (e.isType())
		{
			strKey = e.cast();
		}
		else if (e.isType())
		{
			strKey = to_string(e.cast());
		}
		else if (e.isType())
		{
			strKey = e.cast();
		}
		else if (e.isType())
		{
			strKey = e.cast();
		}
		else
		{
			throw exception(("unsupport type "+ name).c_str());
		}
		if (!this->exist(strKey))
		{
			this->data[strKey] = Elem();
		}
		return this->data[strKey];
	}

	Dict& operator+(Dict& dict)
	{
		this->update(dict);
		return *this;
	}

	void operator=(const Dict& dict)
	{
		this->data.clear();
		this->update(dict);
	}

	void operator+=(Dict dict)
	{
		this->update(dict);
	}


	map::iterator begin()
	{
		return this->data.begin();
	}
	
	map::iterator end()
	{
		return this->data.end();
	}



	void foreach(void callback(string& key, Elem& value))
	{
		for (auto i = this->data.begin(); i != this->data.end(); i++)
		{
			callback((string&)i->first, (Elem&)i->second);
		}
	}

	int size()
	{
		return this->data.size();
	}

	bool empty()
	{
		return this->data.empty();
	}

	bool exist(int key)
	{
		return this->data.find(to_string(key)) != this->data.end();
	}
	bool exist(string key)
	{
		return this->data.find(key) != this->data.end();
	}

	void update(const Dict& dict)
	{
		int a = 0;
		for (auto i = dict.data.begin(); i != dict.data.end(); i++)
		{
			this->data[i->first] = i->second;
		}
	}

	vector keys()
	{
		vector keys;
		for (auto i = this->data.begin(); i != this->data.end(); i++)
		{
			keys.push_back(i->first);
		}
		return keys;
	}
    
    string toStringArray()
	{
		string array="{";
		int count = 0;
		for (auto i = this->begin(); i != this->end(); i++)
		{		
			array = array + i->first + ":" + i->second.toString() + (count == this->size()-1? "":",");
			count++;
		}
		array += "}";
		return array;
	}


private:
	map data;
};

  6. 测试案例

    // cppTest.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//

#include 
#include 
#include 
#include 
#include "List.hpp"
#include "Dict.hpp"

using namespace std;

void listTest()
{
	char c[] = { 'a','b','c','\0' };
	List list1(1, 'a', "hello world", true, (short)1234, (long long)56798, 1.2f, 3.14159264);
	List list2(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
	List list3(11, 12, 13, 14, 15, 16, 17, 18, 19, 20);

	// 往list1结尾追加元素(或 list1+=c;)
	list1.append(c);

	cout << list1.toStringArray() << endl;

	// 遍历list2
	for (auto i = 0; i < list2.size(); i++)
	{
		cout << list2[i].toString();
	}
	cout << endl;

	// 拼接list2和list3
	List listA = list2 + list3;
	cout << listA.toStringArray() << endl;

	// 当List中数据只有C语言基本类型时,List和string可以互相转换
	string byteStr = listA.toByteString();
	List strList = List(byteStr);
	cout << strList.toStringArray() << endl;	

	// 默认情况下,构造List时传入List类型,会将ListA中的元素转移过去,如果第二个参数为falst,则会产生List嵌套
	List(listA,true);
}


void dictTest()
{
	Dict dict1;
	dict1["name"] = "FeJQ";
	dict1["height"] = 180;
	dict1["male"] = true;
	
	if (!dict1.exist("email"))
	{
		dict1["email"] = "a@b.com";
	}

	for (auto i=dict1.begin();i!=dict1.end();i++)
	{
		cout << i->first << ":" << i->second.toString() << endl;
	}
	cout << dict1.toStringArray() << endl;
	
}

int main()
{
	cout << "list test:" << endl;
	listTest();

	cout <

    效果:

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