On Wednesday 16 November 2011, Alexandru Ciobanu wrote: > Hi, > > I was successful in making CMake work with PCRE. As expected, it was > straightforward. > > The problem is that PCRE is also slow. So, I tested the same string and > regex with multiple different libraries in order to assess performance. > > The regular expression in question is: > ([^:]+): warning[ \t]*[0-9]+[ \t]*: > > The string is a 6k character string, a typical compiler command line. (See > my first message for sample code). > > For each library the steps are: > - regcomp() the regular expression > - regexec() the expression on the string > > Here is how much time it takes to process the string *one* time: > current CMake -- 860ms > TRex -- 680ms > PCRE -- 610ms ( with pcre_exec() ) > PCRE -- 990ms ( with pcre_dfa_exec() ) > re2 -- 0.085ms > /usr/include/regex.h -- 0.075ms
I wouldn't have expected this. > As it can be seen re2 and the standard regex.h are orders of magnitude > faster in executing this particular regular expression. > > The difference between PCRE and re2 is also confirmed by this study: > http://swtch.com/~rsc/regexp/regexp3.html > > CONCLUSTION: > - PCRE is not fast enough > > QUESTION: > - is there a reason we shouldn't use the standard regex.h? Does it exist everywhere, e.g. on Windows, e.g. with MSVC 6 ? Alex -- Powered by www.kitware.com Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Follow this link to subscribe/unsubscribe: http://public.kitware.com/cgi-bin/mailman/listinfo/cmake-developers
