c++ - 正则表达式搜索文本然后匹配元素

Question

我想安装一个条件。我已经尝试了很多但没有成功。会有人这么好心帮我吗？

我的目标:如果 SharedKeys 为真则匹配元素 (A B C D)。

SharedKeys = "A","B","C","D"

正则表达式:(?!\")[A-Z]*?(?=\")

匹配元素:A B C D

更新:(SharedKeys)?(?(1)|(?!\")[A-Z]*?(?=\"))

匹配元素:SharedKeys A B C D

链接:https://regex101.com/r/WFxZh4/1

我想我现在已经拥有了我需要的东西，也许可以帮助其他人。

SharedKeys = "A","B","C","D"

BlaBla = "B", "B", "C"

结果:(SharedKeys|BlaBla)?(?(1)|(?!\")[A-Z]*?(?=\"))

匹配元素:SharedKeys A B C D BlaBla B B C

C++ 的结果:[A-Za-z]+|(?!\")[A-Z]*?(?=\") (std::regex)

Answer 1

使用std::regex:

std::string s1( R"(SharedKeys = "A","B","C","D")" );
std::regex rx( "(SharedKeys)?(?(1)|[A-Z](?=\\\"))" );
std::match_results< std::string::const_iterator > mr;

while( std::regex_search( s1, mr, rx ) ){
    std::cout << mr.str() << '\n';
    s1 = mr.suffix().str();
}

输出:

terminate called after throwing an instance of 'std::regex_error'  
what():  Invalid special open parenthesis. Aborted (core dumped)

使用boost::regex:

std::string s1( R"(SharedKeys = "A","B","C","D")" );
boost::regex rx( "(SharedKeys)?(?(1)|[A-Z](?=\\\"))" );
boost::match_results< std::string::const_iterator > mr;

while( boost::regex_search( s1, mr, rx ) ){
    std::cout << mr.str() << '\n';
    s1 = mr.suffix().str();
}

输出:

SharedKeys
A
B
C
D

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在这里你可以看到这两种口味的区别:

source of the screenshot

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注意。 std::regex 有问题，尤其是 gcc version 6.3.0 and lower versions