This is a mini-review, based just on reading the documentation, not on trying to compile anything. My comments on documentation, with a few questions are attached below. Design looks well thought out; library is potentially useful. Documentation was good. I only read the user documentation, not the reference docs. Are you knowledgeable about the problem domain? I've used boost.regex and spirit, as well as using regexes a lot in scripting languages. Do you think the library should be accepted as a Boost library? Yes, but conditional on having benchmarks showing a worthwhile speed improvement over boost.regex. (Or alternatively over spirit.) Without that there is no strong reason to have it in Boost along with both Spirit and boost.regex. Darren ------------------- URLs are relative to http://boost-sandbox.sourceforge.net/libs/xpressive/doc/html/xpressive/ * user_s_guide.html As I read I assumed "sregex" meant static (compile-time) regex. I then thought compile() must be very clever and wondered why bother with the alternative ">>" syntax. So I think you need to make it clearer on this page that sregex means std::string regex, and that compile() is for a run-time regex, and the ">>" syntax is for a compile-time regex. * creating_a_regex_object.html 1. Either the meaning of Perl's /s modifier needs to be defined clearly, or the difference between "_" and "~_n" needs to be shown with an example (incidentally none of your examples at examples.html match strings with carriage-returns). 2. I see I can use icase("Abc") but is there a way to say the whole regex should be case-insensitive? I.e. the equivalent of: "/match something/i" * grammars_and_nested_matches.html In the example that starts: sregex parentheses; parens = '(' should "parens" actually be "parentheses" ? If not, I don't understand what is happening, and this example needs more explanation. 2. In Filtering Nested Results, I wasn't clear what the purpose was. Is it to show all the name matches before all the id matches? If so, choosing a less regular example string would help, e.g. with more names than ids, names following names some of the time, etc. 3. "See the definition of output_nested_results in the Examples section." I think that function should be moved to grammars_and_nested_matches.html; it seemed out of place in examples.html. * Other 1. I'd like to see some fuller examples, that show the I/O part as well. E.g. a full program that takes a list of email addresses on stdin, one per line, and spits out a list of the illegal ones. 2. Benchmarking. I wanted to see the relative speed of compile-time vs. run-time vs. boost::regex (and ideally vs. PCRE or a scripting language) on some realistic application.