Lynn Allan wrote:
Is the following getting closer to "best practice" to use xpressive-static for the kinds of specialized searches I'm attempting. When I'm further along on the learning curve, I'll try to prepare some "apples and apples" timing comparisons between boost::regex, xpressive, spirit, a hand-tuned state-machine searcher, and an automatic FSM generator utility.
I think I'm conforming to the guidelines on this page: X:\DevTools\Boost\libs\xpressive\doc\html\boost_xpressive\user_s_guide\tips_n_tricks.html except I don't understand how to specify syntax_option_type::optimize (does it apply to xpressive-static, or only xpressive-dynamic)?
Static regexes assume the optimize flag.
boost::xpressive::regex_constants::syntax_option_type flags = boost::xpressive::regex_constants::optimize; sregex rexStatic = (s1 = (as_xpr("Sunday") | "Sun")) | (s2 = (as_xpr("Monday") | "Mon")) | (s3 = (as_xpr("Tuesday") | "Tue")) | (s4 = (as_xpr("Wednesday") | "Wed")) | (s5 = (as_xpr("Thursday") | "Thu")) | (s6 = (as_xpr("Friday") | "Fri")) | (s7 = (as_xpr("Saturday") | "Sat")) ;
Yep, you got it.
//??? rexStatic.compile(rexStatic, flags); smatch what;
std::string testStr = "Alternate days of the week are Tue and Thursday and Sat and Monday. " "And then Monday and Wed and Friday and Sun. "; std::string::const_iterator start = testStr.begin(); std::string::const_iterator finish = testStr.end(); int foundCount = 0; while (regex_search(start, finish, what, rexStatic)) { foundCount++; size_t limit = what.size(); size_t matchIndex = 1; while (matchIndex <= limit) { if (what[matchIndex].matched == true) { break; } ++matchIndex; } #ifdef _DEBUG cout << "FoundCount: " << foundCount << " Index: " << static_cast<int>(matchIndex) << " what[0]: " << what[0] << endl; #endif start = what[0].second; }
Ah, you're trying to find all the matches. Check out regex_iterator. sregex_iterator begin(testStr.begin(), testStr.end(), rexStatic), end; for(; begin != end; ++begin, ++foundCount) { smatch const &what = *begin; size_t limit = what.size(); size_t matchIndex = 1; for(; matchIndex <= limit; ++matchIndex) if(what[matchIndex].matched == true) break; #ifdef _DEBUG cout << "FoundCount: " << foundCount << " Index: " << static_cast<int>(matchIndex) << " what[0]: " << what[0] << endl; #endif } HTH, -- Eric Niebler Boost Consulting www.boost-consulting.com