C++11 regex matching capturing group multiple times

Question

Could someone please help me to extract the text between the : and the ^ symbols using a JavaScript (ECMAScript) regular expression in C++11. I do not need to capture the <

Answer 1

With std::regex, you cannot keep mutliple repeated captures when matching a certain string with consecutive repeated patterns.

What you may do is to match the overall texts containing the prefix and the repeated chunks, capture the latter into a separate group, and then use a second smaller regex to grab all the occurrences of the substrings you want separately.

The first regex here may be

hw-descriptor((?::[pmu][^^]*\\^)+)

See the online demo. It will match hw-descriptor and ((?::[pmu][^^]*\\^)+) will capture into Group 1 one or more repetitions of :[pmu][^^]*\^ pattern: :, p/m/u, 0 or more chars other than ^ and then ^. Upon finding a match, use :[pmu][^^]*\^ regex to return all the real "matches".

C++ demo:

static const std::regex gRegex("hw-descriptor((?::[pmu][^^]*\\^)+)", std::regex::icase);
static const std::regex lRegex(":[pmu][^^]*\\^", std::regex::icase);
std::string foo = "hw-descriptor:pTEXT1^:mTEXT2^:uTEXT3^ hw-descriptor:pTEXT8^:mTEXT8^:uTEXT83^";
std::smatch smtch;
for(std::sregex_iterator i = std::sregex_iterator(foo.begin(), foo.end(), gRegex);
                         i != std::sregex_iterator();
                         ++i)
{
    std::smatch m = *i;
    std::cout << "Match value: " << m.str() << std::endl;
    std::string x = m.str(1);
    for(std::sregex_iterator j = std::sregex_iterator(x.begin(), x.end(), lRegex);
                         j != std::sregex_iterator();
                         ++j)
    {
        std::cout << "Element value: " << (*j).str() << std::endl;
    }
}

Output:

Match value: hw-descriptor:pTEXT1^:mTEXT2^:uTEXT3^
Element value: :pTEXT1^
Element value: :mTEXT2^
Element value: :uTEXT3^
Match value: hw-descriptor:pTEXT8^:mTEXT8^:uTEXT83^
Element value: :pTEXT8^
Element value: :mTEXT8^
Element value: :uTEXT83^