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Switch to using pcre::regex instead of boost::regex #190
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Drop dependency on Boost.Regex library and use PCRE-based regex class instead. Using PCRE-based implementation is advantageous compared to using std::regex because it has a much better performance and also supports more regex features, notably the "?<=" look-behind assertions not supported by the standard class, that are used in the existing code. With PCRE, the only regex change needed was the one replacing "\l", which is not recognized by PCRE (nor std::regex) as a character class shorthand, with the explicit use of "[:lower:]". Currently PCRE is used only under POSIX systems and so the fully functional version of test_coding_rules tool can only be built there and a stub version, which simply outputs an error, is built by default under MSW. This shouldn't be a problem in practice, because this tool is only used during lmi development, which is done only on POSIX platforms. The regex unit test has been minimally modified to build, and pass, without Boost.Regex. Finally, remove the last vestiges of Boost libraries from configure and automake makefiles.
Compare PCRE performance with std::regex under POSIX systems, where PCRE is available. The results show that PCRE is 6-12 times faster, even with the simplest possible regexes used in this test, with gcc 10 (previous test_coding_rules benchmarks show that the difference is even more pronounced with more complex regexes or older gcc versions).
The changes of a9bc62f (Count coding-rules complaints, 2021-06-28) made test_coding_rules exit with a non-zero exit code if any coding rules violations were found, but the check_concinnity makefile target still explicitly ignored the failure by using "-" in the make recipe. It is not really clear why was the exit code of test_coding_rules ignored in the first place, as it hadn't been done for the checks performed in the makefile itself prior to the introduction of a separate test_coding_rules program in 7afe844 (Quadruple the speed of 'make check_conformity', 2006-01-18), but it remained the case ever since. Stop doing it now and do fail if either any real problems are found or when running the stub version of test_coding_rules built on the systems without PCRE.
Because only Linux version of this tool is fully functional (while the MSW one just exits with an error), always use it, even in the build targeting MSW. This is enough to make concinnity checks to work in any build.
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Merged as 368ee55 and preceding commits. |
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Drop dependency on Boost.Regex library and use PCRE-based regex class
instead.
Using PCRE-based implementation is advantageous compared to using
std::regex because it has a much better performance and also has more
features, notably it supports "?<=" look-behind assertions not supported
by the standard class, that are used in the existing code.
The only regex change needed was the one replacing "\l", which is not
recognized by PCRE (nor std::regex) as a character class shorthand, with
the explicit use of "[:lower:]".
Currently PCRE is used only under POSIX systems and so the fully
functional version of test_coding_rules tool can only be built there
and a stub version, which simply outputs an error, is built by default
under MSW. This shouldn't be a problem in practice, because this tool is
only used during lmi development, which is done only on POSIX platforms.