How to get a basic preg_match_all replacement for std::string in C++?
with "basic" is meant: Only the operators "+" (->fo开发者_如何学Pythonllowing..) and "|" (->or) are needed.
Prototype:
preg_match_all(std::string pattern, std::string subject, std::vector<std::string> &matches)
Usage Example:
std::vector<std::string> matches;
std::string pattern, subject;
subject = "Some text with a lots of foo foo and " + char(255) + " again " + char(255);
pattern = "/" + char(255) + char(255) + "+|foo+/";
preg_match_all(pattern, subject, matches);
The matches should be available afterwardsa via matches[n]
. Someone got a hint without using boost and/or PCRE? If not, how I got this realized with boost?
This will return a vector of all matches an the index they were found at.
std::vector<std::pair<std::string, unsigned int>> RegexPP::MatchAll(std::string pattern, std::string haystack) {
std::vector<std::pair<std::string, unsigned int>> matches;
std::regex p(pattern);
std::sregex_iterator start(haystack.begin(), haystack.end(), p), end;
for(; start != end; start++) {
auto match = *start; // dereference the iterator to get the match_result
matches.push_back(std::pair<std::string, unsigned int>(match.str(), match.position()));
}
return matches;
}
You could rollup something using std::string::find, doing matches via a functor, and pushing the results onto a string vector.
The way it's realized in boost is probably overkill for what you want -- you first would need to decompose the expression into lexems and then compile a state machine for parsing the given regexp.
Look into Boost.Regex, http://www.boost.org/doc/libs/1_41_0/libs/regex/doc/html/index.html
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