从Vector生成类数据成员 [英] Generating class datamembers from a Vector
问题描述
请考虑以下C ++问题:
Please consider this C++ question:
#include <cstdio>
#include <iostream>
#include <vector>
using namespace std;
class ParseURL{
private:
int qualify; // 0 means we qualify
public:
string node;
string service;
bool primary;
bool health;
string epoch;
// methods
ParseURL(string URL);
~ParseURL();
};
ParseURL::ParseURL(string URL){
vector<string> g2 = {"node", "service", "primary", "health", "epoch"};
for (string tag : g2){
auto found = URL.find(tag);
if ( found != string::npos ){
auto cut_from = found + 1 + tag.size() ;
auto meh = URL.substr(cut_from, URL.substr(cut_from).find("&") );
// is there a way we can avoid these lines below?
if (tag.find("node",0) == 0){
this->node = meh;
} else if (tag.find("service",0) == 0 ){
this->service = meh;
} else if (tag.find("epoch",0) == 0) {
this->epoch = meh;
} else if (tag.find("health",0) == 0){
this->health = (meh == "OK");
} else if (tag.find("primary",0) == 0 ){
this->primary == (this->node == meh);
}
}
}
}
ParseURL::~ParseURL(){
cout << "Tearing Down the class\n";
}
int main(){
char req[] = "GET /register?node=hostrpi3&service=potatoservice&primary=node1&health=OK&epoch=1559345106 HTTP";
string Request = req;
Request = Request.substr(Request.find_first_of(" ") );
Request = Request.substr(0, Request.find(" HTTP"));
ParseURL *a = new ParseURL(Request);
cout.width(12);
cout << "a->node: " << a->node << endl;
cout.width(12);
cout << "a->service: " << a->service << endl;
cout.width(12);
cout << "a->epoch: " << a->epoch << endl;
cout.width(12);
cout << "a->health: " << a->health << endl;
cout.width(12);
cout << "a->primary: " << a->primary << endl;
delete(a);
return 0;
}
我需要基于URL查询字符串表示一个对象,我需要这些标签用向量g2表示,如您所见,我在这些标记中为 ParseURL
制作了数据成员。
I need to represent a object based on URL Query Strings, the tags I need are represented in vector g2, and as you can see, I make datamembers for ParseURL
out of those tags.
o / p如下:
a->node: hostrpi3
a->service: potatoservice
a->epoch: 1559345106
a->health: 1
a->primary: 0
Tearing Down the class
尽管此版本有效,但仍可以改进。尽管在Vector中具有所有功能,但我还是对每个这些属性重复执行 tag.find
。我希望一定有更好的方法。您能指出正确的方向吗?谢谢!
Although this version works, it feels this can be improved much. Despite having it all in the Vector, I am repeatedly doing tag.find
for each of those attributes. There must be a better way, I hope. Could you please point in the right direction? Thanks!
编辑1
谢谢,我按照以下建议更新了构造函数:
Thanks, I updated the constructor following the suggestions:
ParseURL::ParseURL(string URL){
char tags[10][100] = {"node", "service", "primary", "health", "epoch"};
int i = 0;
for (auto tag : tags){
auto found = URL.find(tag);
if ( found != string::npos ){
auto cut_from = found + 1 + strlen(tag);
auto tag_info = URL.substr(cut_from, URL.substr(cut_from).find("&") );
switch (i){
case 0:
this->node = tag_info;
break;
case 1:
this->service = tag_info;
break;
case 2:
this->primary = (this->node == tag_info);
break;
case 3:
this->health = (tag_info == "OK");
break;
case 4:
this->epoch = tag_info;
break;
}
}
i++;
}
}
bash提供了变量的间接引用-是,一个变量可能包含另一个变量的名称:
bash for example, offers indirect reference of variables - that is, one variable may contain the name of another variable:
$ cat indirect.sh
#!/bin/bash
values="value1 value2"
value1="this is value1"
value2="this is value2"
for i in $values; do
echo "$i has value ${!i}"
done
$ ./indirect.sh
value1 has value this is value1
value2 has value this is value2
我一直希望类似的情况存在,但我了解到这里有价值的教训。谢谢!
I was hoping something similar exists for cases like this, nevertheless, I learned valuable lessons here. thank you!
推荐答案
我相信问题可以分解:
- URL解析,然后
- 将结果分配给对象数据成员。
regex提供了紧凑而强大的解决方案,用于将URL键值对(参数)提取到地图中。
regex gives compact and robust solution for extracting URL key value pairs (parameters) into map:
#include <iostream>
#include <iterator>
#include <map>
#include <string>
#include <regex>
using namespace std;
int main()
{
map<string, string> keyValues;
string s = "GET /register?node=hostrpi3&service=potatoservice&primary=node1&health=OK&epoch=1559345106 HTTP";
regex keyValueRegex("[?&](\\w+)=(\\w+)");
auto pairsBegin = std::sregex_iterator(s.begin(), s.end(), keyValueRegex);
auto pairsEnd = std::sregex_iterator();
for (std::sregex_iterator i = pairsBegin; i != pairsEnd; ++i)
{
std::smatch match = *i;
keyValues[match[1]] = match[2];
}
for (auto p : keyValues)
{
cout << p.first << " " << p.second << endl;
}
}
给出输出:
epoch 1559345106
health OK
node hostrpi3
primary node1
service potatoservice
另一种方法(用于非常精细的URL解析)是使用cpp-netlib库(建议用于Boost包含)。
Another approach (for very granular URL parsing) is using cpp-netlib library (proposed for Boost inclusion).
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