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。有人会这么好心帮助我吗？

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

Link: https://regex101.com/r/WFxZh4/1

我想我现在已经拥有了我需要的东西，也许可以帮助别人。

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

Answer 1

与 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)

与 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

在这里你可以看到这两种口味的区别：

source of the screenshot

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

正则表达式搜索文本然后匹配元素

Regex search for Text then match elements

c++

regex

regex-group