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I would like to add boost::algorithm::is_clamped, how to proceed?
by Ivan Matek 13 Aug '21

13 Aug '21

Hi, I would like to add is_clamped (that tests if the value is clamped, similar how we have std::is_sorted, std::sort). What would be the proper procedure? I have never committed to boost, so I have no access to any repository, no "contacts", so I have no idea if small proposals like this require just approval from owner or it needs broader discussion(for example in some cases it would be nice fix for missing chain comparison <https://www.geeksforgeeks.org/chaining-comparison-operators-python/> in core language, but then is_clamped name is not that nice, is_between might be nicer,...). Also I am not sure if this is the best place to ask for directions and do discussions, if you have some slack channel or forum you prefer please let me know. There was a proposal <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1440r0.html>for std::, but it is not in C++20. I have no relation to that proposal. regards, Ivan

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is_constant_evaluated
by Robert Ramey 11 Aug '21

11 Aug '21

Any chance of seeing a feature macro for HAS_IS_CONSTANT_EVALUATED appearing in Boost.Config any time soon? Robert Ramey

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[release] Boost 1.77.0 Release Candidate 1
by Marshall Clow 06 Aug '21

06 Aug '21

The first release candidates for the 1.77.0 release are now available at: <https://boostorg.jfrog.io/artifactory/main/release/1.77.0/source/> The SHA256 checksums are as follows: fc9f85fc030e233142908241af7a846e60630aa7388de9a5fafb1f3a26840854 boost_1_77_0_rc1.tar.bz2 f2dd9722b21450daf5ce8ef82c2d99c7ec304f913ee6c6b7f047d5639503dda1 boost_1_77_0_rc1.7z 5347464af5b14ac54bb945dc68f1dd7c56f0dad7262816b956138fc53bcc0131 boost_1_77_0_rc1.tar.gz d2886ceff60c35fc6dc9120e8faa960c1e9535f2d7ce447469eae9836110ea77 boost_1_77_0_rc1.zip As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. -- The Release managers

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[multiprecision/mpc][math/quadrature] Why boost::multiprecision::exp gets stuck when evaluating complex-valued integral?
by Kirill Kudashkin 05 Aug '21

05 Aug '21

Dear all, I have encountered a problem while using Boost C++ libraries ( multiprecision/mpc.hpp, math/quadrature) which I cannot resolve. This problems appears when running the following piece of code || |#include <boost/math/constants/constants.hpp> #include <boost/math/quadrature/exp_sinh.hpp> #include <boost/multiprecision/mpc.hpp> #include <boost/multiprecision/mpfr.hpp> #include <boost/math/special_functions/fpclassify.hpp> namespace mpns = boost::multiprecision; typedef mpns::number<boost::multiprecision::mpc_complex_backend <50> > mpc_type ; typedef mpc_type::value_type mp_type ; int main() { using boost::math::constants::root_pi ; mpc_type z{mp_type(1),mp_type(1)} ; auto f = [&](mp_type x) { //actually I did not test if all these conditions are needed... if (boost::math::fpclassify<mp_type> (x) == FP_ZERO) { return mpc_type(mp_type(1)) ; }; if (boost::math::fpclassify<mp_type> (x) == FP_INFINITE) { return mpc_type(mp_type(0)) ; }; mp_type x2 = mpns::pow(x,2U) ; if (boost::math::fpclassify<mp_type> (x2) == FP_ZERO) { return mpc_type(mp_type(1)) ; }; if (boost::math::fpclassify<mp_type> (x2) == FP_INFINITE) { return mpc_type(mp_type(0)) ; }; mpc_type ex2 = mpns::exp(-z*x2) ; if (boost::math::fpclassify<mpc_type> (ex2) == FP_ZERO) { return mpc_type(mp_type(0)) ; }; return ex2 ; } ; mp_type termination = boost::math::tools::root_epsilon <mp_type> () ; mp_type error; mp_type L1; size_t max_halvings = 12; boost::math::quadrature::exp_sinh<mp_type> integrator(max_halvings) ; mpc_type res = integrator.integrate(f,termination,&error,&L1) ; mpc_type div = 2U*mpns::sqrt(z) ; mpc_type result = (mpc_type(root_pi<mp_type> ())/div) - res ; return 0; } | ||Namely, the problem appears when evaluating the exponent. The code is compiled without any problems, but hangs on computing | mpc_type ex2 = mpns::exp(-z*x2) ;| It was possible to go into the function while debugging. It crashed eventually, when the compiler reached "unable to resolve non-existing file.../src/init2.c". I let it run for a while checking the call stack. It appears that the programs is stuck atcalling ___gmpn_sub_n_coreisbr(). Or better, in the call stuck it appeared frequently. I did several tests. The real-valued version (with mpfr_backend <2000>) works without any problems. cpp_complex_backend <100> works fine, but I could not test higher precision yet, since it is much slower. I found a work-around which is not ideal. Namely, mpc_type ex2 = mpc_type(mpns::exp(x2)) ; mpc_type ezx2 = mpns::pow(ex2,-z) ; works fine with mpc_complex_backend <2000>. The lambda-function as it is declared in the code above works and yields correct numbers. The problem appears when it is called from the integrator. My system. I use openSUSE Tumbeleweed. I installed boost libraries as provided by |boost_1_76_0-gnu-mpich-hpc-devel.| Complier -> g++, cppStandard gnu+17. I check that I have all libs, e.g. libgmp, libmpc, libmpfr and etc. All headers are present (the programs is complied without any warnings). Sorry for a lengthy question. Thank you in advance and Best wishes, Kirill ||

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Reminder: The Master branch will be closing for the 1.77.0 release on WEDNESDAY 4-August
by Marshall Clow 04 Aug '21

04 Aug '21

Release calendar here: https://www.boost.org/development/index.html — Marshall

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Re: [boost] Reminder: The Master branch will be closing for the 1.77.0 release on WEDNESDAY 4-August
by Gavin Lambert 03 Aug '21

03 Aug '21

On 3/08/2021 11:57 am, Andrey Semashev wrote: >> The docker image that the tools get run from doesn’t have “linux/magic.h” >> >> More as we discover it. > > I would like to know more about this issue. In particular, what Linux > system lacks this file (distro, kernel version, etc.). Maybe, this is > worth fixing before the release. Git history suggests that the file started existing in linux kernel 2.6.19 and remains since. Although it moved from one folder to another in the internal kernel source tree in kernel 3.7, but that shouldn't affect its existence in the userspace include dirs, unless something is using the wrong include paths.

3 3

Regexp performance guarantees
by Phil Endecott 30 Jul '21

30 Jul '21

Dear Experts, I recently wanted to add some input-sanitising code to a C++ web application, and as I had some existing Javascript code I decided to port its regex-based input checking to the C++ code. This didn't go as well as I had expected! Here's an example of the sort of thing I have: if (!regexp_match(s, regex("[A-Za-z0-9-_/]{1,8192}"))) throw MalformedInput(); The Javascript equivalent seems to be fine. In C++, with libstdc++'s regex implementation, it seems to take about 2 seconds to run. Boost.Regex didn't like the '-' after the '9' but when I fixed that the execution time became negligible. Boost.Xpressive seems also to be fast. On investigation it seems that this is due to there being two different algorithms, one of which (DFA) is linear in the string size but exponential in the pattern size (which in this case seems to mean exponential in the max repeat value of 8192), and the other (backtracking) is linear in the pattern size but exponential in the string size. It seems that the standard deliberately doesn't specify complexity guarantees for std::regex, leaving the choice of algorithm to the implementation. I find this a bit surprising. It's true that both algorithms have their strengths, but not knowing which you are going to get is the worst of both worlds - you would have to assume that it will be exponential in both pattern and string sizes in portable code! (Imagine a container that doesn't disclose whether it has vector or list complexity!) So I'm wondering if it would be useful for regex libraries to somehow be explicit about which algorithm they are and what the complexity is. Compare, for example, with the text search algorithms (Boyer-Moore etc) which indicate the algorithm in their names. Could we have regex_dfa / regex_backtracking, or something? Now having said that, I think that what I really need for my application is something that is worst-case linear in both the pattern size and the input string. I'm not sure if the apparently-fast Boost.Regex algorithm has a worst-case input that is slow. ("Regular Expression Denial Of Service"). It's clear that my example can be written without a regex as a simple linear loop, and maybe some regex libraries have heuristics that do that. Thoughts anyone? Regards, Phil.

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[release] 1.77.0 post-beta merges
by Marshall Clow 30 Jul '21

30 Jul '21

The master branch is is now open for post-beta merges, but only as described in the Post-Beta Merge Policy. See <https://github.com/boostorg/wiki/wiki/Releases%3A-Beta-Merge-Policy> Reminder: The master branch closes for the release on Wednesday, August 4th. Full calendar here: https://www.boost.org/development/ <https://www.boost.org/development/> — Marshall P.S Doc changes and test changes do NOT require release manager approval to be merged.

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Different Lib/CMake Layout between Pre-Build-Binaries and Build from source
by Dennis Luehring 26 Jul '21

26 Jul '21

target_link_libaries(... Boost::boost) seems not to work if the stagedir/<lib> folder is missing but the pre-build binaries missing this folder https://sourceforge.net/projects/boost/files/boost-binaries/1.75.0/ https://sourceforge.net/projects/boost/files/boost-binaries/1.75.0/boost_1_… boost_1_75_0 <boost> ... bootstrap.bat bootstrap.sh <lib64-msvc-14.1> <cmake> *.lib if i build 1.75.0 from source with b2 --toolset=msvc-14.1 --stagedir=./lib64-msvc-14.1 address-model=64 architecture=x86 link=static threading=multi i've get this hierachy c:\Boost\boost_1_75_0 <boost> ... bootstrap.bat bootstrap.sh ... <lib64-msvc-14.1> <-- stagedir <lib> <cmake> *.lib what is the very same hierarchy with Qt6 cmake-configs (so its seems to be "more" standard) C:\Qt\6.1.2 <msvc2017_64> <-- aka "stagedir" <lib> <cmake> Qt6*.lib why does the pre build binary package got a different hierarchy?

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[bimap][PR RFC] Add std::initializer_list constructor
by Hu Jialun 23 Jul '21

23 Jul '21

C++11 allows list initialization for classes. STL map has been added a constructor with the signature map(initializer_list<value_type> il, const allocator_type& alloc = allocator_type()); Added a similar constructor to bimap, allowing for initialization in the form of initializer list, such as boost::bimap<double, long> tdn { {114.514, 1919}, {891.931, 810} }; --- Seems that the pull request is not being seen for a while... Could someone please take a quick look at it and possibly give some directions? :) https://github.com/boostorg/bimap/pull/31 include/boost/bimap/bimap.hpp | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/include/boost/bimap/bimap.hpp b/include/boost/bimap/bimap.hpp index 5fe7a3f..a3603e5 100644 --- a/include/boost/bimap/bimap.hpp +++ b/include/boost/bimap/bimap.hpp @@ -265,6 +265,29 @@ class bimap {} + #ifndef BOOST_NO_CXX11_HDR_INITIALIZER_LIST + bimap(std::initializer_list<BOOST_DEDUCED_TYPENAME base_::core_type::value_type> init, + const allocator_type& al = allocator_type()) : + + base_::relation_set( + ::boost::multi_index::get< + BOOST_DEDUCED_TYPENAME base_::logic_relation_set_tag>(core) + ), + + core(init,ctor_args_list(),al), + + left ( + ::boost::multi_index::get< + BOOST_DEDUCED_TYPENAME base_::logic_left_tag>(core) + ), + right ( + ::boost::multi_index::get< + BOOST_DEDUCED_TYPENAME base_::logic_right_tag>(core) + ) + + {} + #endif + bimap(const bimap& x) : base_::relation_set(

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