July 2012 - Boost - lists.boost.org

[stratified] library for micro-/userland-threads
by Oliver Kowalke 04 Jul '12

04 Jul '12

Hi, some of the community members ask me to provide a micro-/userland-thread library based on boost.context - I hope boost.stratified is a sufficient implementation. The library contains classes and interfaces similar to boost.thread. Examples and documentation (not finished and needs some updates/correction) is included. I hope I get some feedback from you. best regards, Oliver source: http://olk.bplaced.net/boost-stratified.zip documentation: http://olk.bplaced.net/boost/libs/stratified/doc/html/

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[c++11] compile_if utility
by Lorenzo Caminiti 04 Jul '12

04 Jul '12

Hello all, I was thinking how to program assertion requirements in C++11. I need to program something like this if "has_equal_to<T>" then "assert(back() == value)" else do nothing, don't even compile "assert(back() == value)" Using C++11 lambdas, I was able to program a compile_if utility to do the following: compile_if< boost::has_equal_to<T> >([&]() { assert(this->back() == value); // compiled and executed iff has_equal_to<T> }); Any interest in adding compile_if to Boost.Utility? It could be renamed exec_if if compile_if is too "strong". I didn't play with compile_if much so there might cases where it doesn't work... but I wanted to share it with the ML anyway: #include <boost/type_traits.hpp> #include <cassert> #include <vector> #include <iostream> template< bool Boolean > struct compile_if_c { template< typename UnaryFunc > compile_if_c ( UnaryFunc f ) { std::cout << "compiling" << std::endl; f(); } }; template< > struct compile_if_c <false> { compile_if_c ( ... ) { std::cout << "not compiling" << std::endl; } }; template< class BooleanMetafunc, class UnaryFunc > void compile_if ( UnaryFunc f ) { compile_if_c<BooleanMetafunc::value> compile(f); } template< typename T > class vector { public: typedef typename std::vector<T>::const_reference const_reference; public: void push_back ( T const& value ) { vector_.push_back(value); compile_if< boost::has_equal_to<T> >([&]() { assert(this->back() == value); }); } public: const_reference back ( void ) const { return vector_.back(); } private: std::vector<T> vector_; }; struct x {}; // no operator== int main ( void ) { vector<x>().push_back(x()); // no == so skip assertion back() == value vector<int>().push_back(123); // has == so assert back() == value return 0; } Thanks. --Lorenzo P.S. Eh, if C++11 lambda had constant captures [const&](){ assert(this->back() == value; } I could have even made the assertion constant-correct...

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[Review Request] Inclusion of the Boost.Polygon Voronoi Library
by Andrii Sydorchuk 04 Jul '12

04 Jul '12

Boost community, It has been two years since I started development of the Voronoi library as part of the Google Summer of Code 2010. Finally I feel that the library is ready to become public and would like to request a review for the inclusion into the Boost.Polygon library. Features: - Robust and efficient implementation of the sweepline algorithm that allows to construct Voronoi diagram, Delaunay triangulation and medial axis of a set of points and line segments. - Coordinates of the output geometries are computed within the 64 machine epsilon relative error (6 mantissa bits). - Voronoi diagram data structure that allows efficient traversal and data association with the output Voronoi graph. - No 3rd party dependencies (e.g. GMP, MPFR), all the required multiple precision types are implemented as part of the library. - The input and output coordinate type domains are configurable via coordinate type traits, thus allowing to compute coordinates of the Voronoi vertices within any required precision. - The full construction of the Voronoi diagram of 100 000 points takes only 0.27 seconds (see benchmarks). The full list of features could be found here: http://svn.boost.org/svn/boost/sandbox/gtl/doc/voronoi_main.htm Limitations: - Input geometries should have integer coordinates; - Input segment data sets should not contain intersection points, except segment's endpoints. Information on why the first limitation is not sufficient is explained here: http://svn.boost.org/svn/boost/sandbox/gtl/doc/voronoi_advanced_tutorial.htm The second limitation could be waved using native Boost.Polygon functionality: http://svn.boost.org/svn/boost/sandbox/gtl/doc/gtl_polygon_set_concept.htm Resources: The code is already merged with the Boost.Polygon sandbox branch. All the Voronoi related files are prefixed with "voronoi". - Code location: http://svn.boost.org/svn/boost/sandbox/gtl - Main documentation page: http://svn.boost.org/svn/boost/sandbox/gtl/doc/voronoi_main.htm or http://svn.boost.org/svn/boost/sandbox/gtl/doc/index.htm - Benchmarks: http://svn.boost.org/svn/boost/sandbox/gtl/doc/voronoi_benchmark.htm - Examples: http://svn.boost.org/svn/boost/sandbox/gtl/libs/polygon/example/output_data/ - Tests: http://svn.boost.org/svn/boost/sandbox/gtl/libs/polygon/test/ - Tutorials: http://svn.boost.org/svn/boost/sandbox/gtl/doc/voronoi_basic_tutorial.htm and http://svn.boost.org/svn/boost/sandbox/gtl/doc/voronoi_advanced_tutorial.htm - Official Google+ page: https://plus.google.com/b/109395909314556242008/ Review manager: I would kindly ask Simonson, Lucanus J. the author of the Boost.Polygon library to be my review manager. PS. The library was designed in a user friendly way, so I would invite everyone to give it a try! No configuration of the geometric or predicate kernels is required. Simply follow the basic tutorial: http://svn.boost.org/svn/boost/sandbox/gtl/doc/voronoi_basic_tutorial.htm Thanks and have fun, Andrii

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[ratio] error in template specialization: template parameter n1 depends on another template parameter
by Krzysztof Czainski 04 Jul '12

04 Jul '12

Hello, In order to use Boost.Ratio with my poor compiler from TI, I had to apply the attached fix. I suspect a more general fix would be desirable, should such a fix be added to Boost. However, before investigating further, I'd like to ask, if such a fix would be welcome, or is my compiler too poor to be supported by Boost.Ratio? Regards, Kris

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boost.stratified -> boost.fiber
by Oliver Kowalke 04 Jul '12

04 Jul '12

Hi, as requested I've renamed boost.stratified to boost.fiber. archive is avialble at : http://olk.bplaced.net/boost-fiber.zip for those in Japan, Korea, etc please use http://www.hidemyass.com/ (proxy) to circumvent http 403 from the web-hoster. regards, Oliver

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[type_index] C++03 implementation in boost?
by Agustín K-ballo Bergé 03 Jul '12

03 Jul '12

After crafting my own `type_info_ptr` as a thin wrapper to be able to use `std::type_info` as key in maps, I found out about the new `std::type_index` in C++11. It seems that a C++03 implementation would be trivial, except for the hashing functionality. Could that functionality be built by leveraging implementation specific details like whether there is only one `type_info` instance for each type, or whether the name member function returns distinct values? I believe it would be a nice addition to Boost, perhaps as part of the utility library. It would be useful for those wanting to use C++11 features while still writing C++03 compatible code. Agustín K-ballo Bergé.- http://fusionfenix.com

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Large Integer Library
by Michael Tryhorn 03 Jul '12

03 Jul '12

Dear Boosters, I have written a Boost-compatible library for the representation and manipulation of integers of large or arbitrary size (including 128bit and above). I would like to make a preliminary submission of this library for your review and input, for potential inclusion into Boost v1.51.0 or later, as per the Boost Library Submission Process. The library and all its files are publicly available on github, at: http://github.com/mjtryhorn/Boost.LargeInt A tagged .zip of these files (v1.0.0) is available for download at: http://github.com/mjtryhorn/Boost.LargeInt/tags This library has been written for strict conformance to C++03 and the Boost coding guidelines. This library is also header-only, and as such may be directly merged into existing Boost installations without the need for recompilation. All files are distributed under the Boost Software License, Version 1.0. Now a quick explanation of why I've written this library and what it does: I have found myself on several occasions to be working with unsigned 64bit numbers, mostly for the sizes of files or C++ collections. Where I had a need to perform a calculation upon those numbers, there was often the possibility of overflow. 128bit integers would have been an appropriate fix, but these are either entirely unavailable, non-portable, or in a library which I preferred not to use either due to its complexity or incompatible licensing. Floating-point arithmetic is also a means around the problem, but is inherently inaccurate. I decided to fix this problem once-and-for-all by writing a new integer arithmetic library, making judicious use of C++'s template-metaprogramming and Boost to make my solution both as simple and as transparent as possible. Now, what started out as 128bit integers for my own use has grown into a fully- functional library which has the ability to compose any two integer or integer- like types into a new, larger, signed or unsigned integer type, including all the standard integral operators and a number of utility functions to support them. Thus, Boost.LargeInt supports not only signed and unsigned 128bit integer arithmetic but 24bit, 64bit, 160bit, 192bit, 256bit, 512bit and more. Boost.LargeInt is compatible and has been tested with the following compilers and platforms: GNU GCC 4.6.1, 4.6.2 (Linux, Ubuntu 11.10 (64bit) & openSUSE 12.1 (32bit)) Borland C++ 5.6.4 (Windows XP SP3, Borland C++ Builder 6) Microsoft Visual C++ 2010 (Windows XP SP3, Microsoft Visual Studio 2010) (I have also tried to add compatibility for Microsoft Visual C++ 6, but unfortunately this compiler's support for template-metaprogramming is insufficient and the tests for Boost.LargeInt fail to compile.) Documentation is included in BoostBook format (.qbk), but a pre-compiled version is available alongside the library code itself for your convenience. Please, if you have the time, download this library and give it a try. Any comments, or information upon its compatibility (or lack thereof) with compilers which are or are not listed would be greatly appreciated. If no-one has any comments (I think that unlikely ;-) ), then I shall resubmit this library for formal review. Thanks, Michael J. Tryhorn

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CRC 16 Bit Implementation
by GAURAV GUPTA 03 Jul '12

03 Jul '12

Hi, In my application I need to use crc_64_type. I did not find its implemetation in crc.hpp. Anyone implemented it? -- Regards, Gaurav

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[range] treating N-ary function with N-1 default args as unary
by Nathan Ridge 03 Jul '12

03 Jul '12

Hi, Some Boost.Range adaptors, such as 'transformed' or 'filtered', require a unary function. The documentation does not formally define "unary function", but it's pretty clear what it ought to be: a function (object) that's callable with one argument. Thus, to me, the following is a perfectly valid unary function: int foo(int a, int b = 0); as it is callable with one argument. However, Boost.Range does not accept such a function as an argument to 'transformed' or 'filtered'. For example, the following code: #include <boost/range/adaptor/transformed.hpp> int foo(int a, int b = 0); int main() { int A[5]; A | boost::adaptors::transformed(foo); } produces the following compiler errors (recent Boost trunk, with GCC 4.7): In file included from boost/preprocessor/iteration/detail/iter/forward1.hpp:52:0, from boost/utility/result_of.hpp:113, from boost/iterator/transform_iterator.hpp:23, from boost/range/adaptor/transformed.hpp:16, from test.cpp:1: boost/utility/detail/result_of_iterate.hpp: In instantiation of 'struct boost::detail::cpp0x_result_of_impl<int (* const(int&))(int, int)>': boost/utility/detail/result_of_iterate.hpp:46:8: required from 'struct boost::result_of<int (* const(int&))(int, int)>' boost/mpl/eval_if.hpp:38:31: required from 'struct boost::mpl::eval_if<boost::is_same<boost::use_default, boost::use_default>, boost::result_of<int (* const(int&))(int, int)>, boost::mpl::identity<boost::use_default> >' boost/iterator/iterator_adaptor.hpp:160:12: required from 'struct boost::detail::ia_dflt_help<boost::use_default, boost::result_of<int (* const(int&))(int, int)> >' boost/iterator/transform_iterator.hpp:50:17: required from 'struct boost::detail::transform_iterator_base<int (*)(int, int), int*, boost::use_default, boost::use_default>' c++/4.7.0/bits/stl_iterator_base_types.h:143:1: recursively required from 'constexpr const bool std::__has_iterator_category_helper<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >::value' c++/4.7.0/bits/stl_iterator_base_types.h:143:1: required from 'struct std::__has_iterator_category<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >' c++/4.7.0/bits/stl_iterator_base_types.h:160:12: required from 'struct std::iterator_traits<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >' boost/detail/iterator.hpp:81:8: required from 'struct boost::detail::iterator_traits<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >' boost/iterator/iterator_traits.hpp:30:75: required from 'struct boost::iterator_value<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >' boost/range/iterator_range_core.hpp:139:49: required from 'class boost::iterator_range<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >' boost/range/adaptor/transformed.hpp:25:16: required from 'struct boost::range_detail::transformed_range<int (*)(int, int), int [5]>' test.cpp:8:41: required from here boost/utility/detail/result_of_iterate.hpp:69:5: error: too few arguments to function In file included from boost/range/iterator_range_core.hpp:22:0, from boost/range/iterator_range.hpp:13, from boost/range/adaptor/transformed.hpp:15, from test.cpp:1: boost/iterator/iterator_traits.hpp: In instantiation of 'struct boost::iterator_value<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >': boost/range/iterator_range_core.hpp:139:49: required from 'class boost::iterator_range<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >' boost/range/adaptor/transformed.hpp:25:16: required from 'struct boost::range_detail::transformed_range<int (*)(int, int), int [5]>' test.cpp:8:41: required from here boost/iterator/iterator_traits.hpp:30:75: error: no type named 'value_type' in 'struct boost::detail::iterator_traits<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >' boost/iterator/iterator_traits.hpp: In instantiation of 'struct boost::iterator_difference<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >': boost/range/iterator_range_core.hpp:143:54: required from 'class boost::iterator_range<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >' boost/range/adaptor/transformed.hpp:25:16: required from 'struct boost::range_detail::transformed_range<int (*)(int, int), int [5]>' test.cpp:8:41: required from here boost/iterator/iterator_traits.hpp:49:80: error: no type named 'difference_type' in 'struct boost::detail::iterator_traits<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >' boost/iterator/iterator_traits.hpp: In instantiation of 'struct boost::iterator_reference<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >': boost/range/iterator_range_core.hpp:157:53: required from 'class boost::iterator_range<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >' boost/range/adaptor/transformed.hpp:25:16: required from 'struct boost::range_detail::transformed_range<int (*)(int, int), int [5]>' test.cpp:8:41: required from here boost/iterator/iterator_traits.hpp:36:74: error: no type named 'reference' in 'struct boost::detail::iterator_traits<boost::transform_iterator<int (*)(int, int), int*, boost::use_default, boost::use_default> >' Would it be possible to treat N-ary functions with N-1 default arguments as unary? Thanks, Nate

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[Trac] New components
by Daniel James 03 Jul '12

03 Jul '12

Hello, Please can someone with the appropriate trac permissions add two new components "functional/overloaded function" and "local function", both have maintainer "lcaminiti". Maybe also "utility/identity type", or does that come under "utility"? thanks, Daniel

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