如何在C ++ 11中使用正则表达式匹配多个模式 [英] How to match multiple patterns with a regex in C++ 11

问题描述

假设有一个名为path的字符串，需要匹配多个模式.正则表达式字符串如下:

Suppose there is a string named path that needs to match multiple patterns. The regular expression string is as follows:

std::string regexString="(/api/Attachment)|(/api/Attachment/upload)|(/api/Attachment/download)|(/api/v1/ApiTest)|(/api/v1/ApiTest/get/[^/]*/[^/]*)|(/api/v1/ApiTest/[^/]*/List)";

匹配的代码如下:

std::smatch result;
if (std::regex_match(path, result, regexString))
{
    for (size_t i = 1; i < result.size(); i++)
    {
        /// Question: Is there any better way to find the sub-match index without using a loop?
        if (!result[i].matched)
            continue;
        if (result[i].str() == path)
        {
            std::cout<<"Match a pattern with index "<<i<<std::endl;
            /// Do something with it;
            break;
        }
     }
 }
 else
 {
     std::cout<<"Match none"<<std::endl;
 }

上面的程序可以工作，但是考虑到大量的模式，其中的循环有点难看且效率低下.如代码中的注释所示，我的问题是有没有一种方法可以找到不使用循环的子匹配索引?

The above program works, but considering a large number of patterns, the loop in it is a bit ugly and inefficient. As the comments in the code show, my question is is there a way to find the sub-match index without using loops?

任何评论将不胜感激，谢谢！

Any comments would be greatly appreciated, thank you!

推荐答案

尝试仅使用覆盖所有变体的单个交替.在下面的模式中，我还交替关闭捕获.这给我们留下了相当简单的匹配逻辑.如果 smatch 结果没有有一个条目，则它应该是具有完整匹配路径的单个条目.否则，它应该为空.

Try just using a single alternation which covers all variations. In the pattern below, I also turn off capturing in the alternation. This leaves us with fairly straightforward matching logic. If the smatch result does have an entry, then it should be a single entry with the entire matching path. Otherwise, it should be empty.

std::string regexString="/api/(?:Attachment|Attachment/upload|Attachment/download|v1/ApiTest|v1/ApiTest/get/[^/]*/[^/]*|v1/ApiTest/[^/]*/List)";
std::string s ("/api/Attachment/upload");
std::regex e (regexString);

std::smatch sm;
std::regex_match (s,sm,e);

if (sm.size() > 0) {
    std::cout << "found a matching path: " << sm[0];
}

found a matching path: /api/Attachment/upload

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