August 2012 - Boost-users - lists.preview.boost.org

[thread_group] How to limit the number of simultaneous threads
by Olivier Tournaire 09 Aug '12

09 Aug '12

Hi all, I would like to add some multithreading in my application. Suppose I have a set of m tasks to do, and I want to limit the number of simultaneous threads to n. I have really no idea on how to do this and would like to have some hints. Could you help me? Regards

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get milliseconds from boost::posix_time::time_duration
by Roland Uuesoo 09 Aug '12

09 Aug '12

Hi. I have a question regarding boost date_time library. Class time_duration doesn't have milliseconds() accessor function, what is the optimal way to get number of milliseconds using namespace boost::posix_time; ptime t1(date(2012,Aug,9), hours(19)+minutes(10)+seconds(24)+milliseconds(954)); int millisecs=t1.time_of_day().total_milliseconds()%1000; // result must be 954 Thanks, Roland

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Spriti parser for boolean expression
by soumeng78 09 Aug '12

09 Aug '12

Hi, I'm using spirit first time. I'm trying to write a boolean expression (with only &, | and ! operators) parser. I've defined my grammar like following: template <typename Iterator> struct boolean_expression_parser : qi::grammar<Iterator, std::string(), ascii::space_type> { boolean_expression_parser() : boolean_expression_parser::base_type(expr) { using namespace qi; using ascii::char_; using boost::spirit::ascii::alnum; using namespace qi::labels; using phoenix::construct; using phoenix::val; operand %= lexeme[+(alnum)]; simple_expr %= ('(' > expr > ')') | operand; unary_expr %= ('!' > simple_expr ) ; and_expr %= ( expr > '*' > expr); or_expr %= (expr > '|' > expr); expr %= simple_expr | unary_expr | *and_expr | *or_expr; // on_error<fail> // ( // unary_expr, // std::cout // << val("Error! Expecting ") // << _4 // what failed? // << val(" here: \"") // << construct<std::string>(_3, _2) // iterators to error-pos, end // << val("\"") // << std::endl // ); } qi::rule<Iterator, std::string(), ascii::space_type> operand; qi::rule<Iterator, std::string(), ascii::space_type> simple_expr; qi::rule<Iterator, std::string(), ascii::space_type> unary_expr; qi::rule<Iterator, std::string(), ascii::space_type> and_expr; qi::rule<Iterator, std::string(), ascii::space_type> or_expr; qi::rule<Iterator, std::string(), ascii::space_type> expr; }; I'm facing few hurdles here: 1. It's not working for any binary expression (like 'A + B'). It's working fine for unary expressions (like '!(A)' or '(!A)'. Can someone point me what I'm doing wrong? 2. I want store it in tree form (as I want to build a BDD out of it). Can someone point me how to do that? 3. Also, why on_error<> is not working even when I enable it? I'm using boost 1.49 and gcc-4.2.2. Regards, ~ Soumen -- View this message in context: http://boost.2283326.n4.nabble.com/Spriti-parser-for-boolean-expression-tp4… Sent from the Boost - Users mailing list archive at Nabble.com.

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statically linked boost libs with VS2010 missing ?
by trevor＠nurotek.com.au 08 Aug '12

08 Aug '12

Hi all, I'm new to boost, and I'm trying to compile a windows console app statically so the end user doesn't need vcredist. I've changed my code generation options to use /mt (static multithreaded) instead of dynamic multithreaded, but the linker cannot find any libs with libboost*-sgd*.lib (ie.any static boost libs), and they certainly don't exist on my computer. I've performed a --clean-all and recompiled boost using "b2 link=static", but the libs are still missing, even though the compile seems to work fine - and the generated libs are actually following the dynamic naming convention, not the static convention. Is this some MSVC toolchain issue ? Is there another option I need to be using for this toolchain ? thanks Trevor.

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boost::asio UnregisterWaitEx RegisterWaitForSingleObject has not been declared
by Vincent 08 Aug '12

08 Aug '12

Dear Boost'ers, I'm facing compilation troubles while using boost::asio for asynchronous timers. Including the asio.hpp header raises compilation error on Windows (Windows 7 64 bits) but not on GNU/Linux & Mac OS X: #include <boost/asio.hpp> main error messages (full error output below): ..\Tools\boost\current\boost\asio\detail\impl\win_object_handle_service.ipp:109: error: '::UnregisterWaitEx' has not been declared ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp:379: error: 'RegisterWaitForSingleObject' was not declared in this scope I tried either with a complete project (via qmake + Qt Creator), either with a "hello world" example compiled with g++ (mingw under the hood): g++ testasio.cpp -I..\Tools\boost\current -L..\Tools\boost\current\stage\lib -lboost_system-mgw44-mt-1_49 -D_WIN32_WINDOWS Where the source code example is copy-pasted from "Timer asynchrone" (it's in french but the code is universal ;-) ) http://gwenael-dunand.developpez.com/tutoriels/cpp/boost/asio/#LIII-B Thanks, Vincent Full g++ output: In file included from ..\Tools\boost\current/boost/asio/detail/win_object_handle_service.hpp:180, from ..\Tools\boost\current/boost/asio/windows/object_handle_service.hpp:24, from ..\Tools\boost\current/boost/asio/windows/basic_object_handle.hpp:27, from ..\Tools\boost\current/boost/asio.hpp:99, ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp: In member function 'void boost::asio::detail::win_object_handle_service::move_construct(boost::asio::detail::win_object_handle_service::implementation_type&, boost::asio::detail::win_object_handle_service::implementation_type&)': ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp:109: error: '::UnregisterWaitEx' has not been declared ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp: In member function 'void boost::asio::detail::win_object_handle_service::move_assign(boost::asio::detail::win_object_handle_service::implementation_type&, boost::asio::detail::win_object_handle_service&, boost::asio::detail::win_object_handle_service::implementation_type&)': ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp:161: error: '::UnregisterWaitEx' has not been declared ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp: In member function 'void boost::asio::detail::win_object_handle_service::destroy(boost::asio::detail::win_object_handle_service::implementation_type&)': ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp:203: error: '::UnregisterWaitEx' has not been declared ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp: In member function 'boost::system::error_code boost::asio::detail::win_object_handle_service::close(boost::asio::detail::win_object_handle_service::implementation_type&, boost::system::error_code&)': ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp:254: error: '::UnregisterWaitEx' has not been declared ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp: In member function 'boost::system::error_code boost::asio::detail::win_object_handle_service::cancel(boost::asio::detail::win_object_handle_service::implementation_type&, boost::system::error_code&)': ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp:305: error: '::UnregisterWaitEx' has not been declared ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp: In member function 'void boost::asio::detail::win_object_handle_service::register_wait_callback(boost::asio::detail::win_object_handle_service::implementation_type&, boost::asio::detail::scoped_lock<boost::asio::detail::win_mutex>&)': ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp:379: error: 'RegisterWaitForSingleObject' was not declared in this scope ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp: In static member function 'static void boost::asio::detail::win_object_handle_service::wait_callback(void*, BOOLEAN)': ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp:405: error: '::UnregisterWaitEx' has not been declared ..\Tools\boost\current/boost/asio/detail/impl/win_object_handle_service.ipp:421: error: 'RegisterWaitForSingleObject' was not declared in this scope

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Meeting C++ - Full Program + Early Bird
by Jens Weller 08 Aug '12

08 Aug '12

Hi C++ & boost Community, just a short note to those who are interested in C++ conferences: The Schedule of Meeting C++ is online: http://meetingcpp.com/index.php/schedule.html The Keynote "Good C++11 Coding Style" is held by Michael Wong, the focus is on C++11 and boost. Early Bird Tickets are still available for one week until next wednesday! regards, Jens Weller

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[boost.serialization] shared object plugin
by Giampiero Gabbiani 08 Aug '12

08 Aug '12

Hi together, inside the application I'm writing is defined a base class and a factory for the creation of instances through a number of plugins. The plugins auto registers when theis shared objects are dynamically loaded from the application. Each plugin instance is derived from a pure abstract interface defined in the application and used from the plugins through an header. The application maintains a list of these plugins as a member of an object. I would like use boost.serialization library in order to serialize the application container object with all the plugins contained. The library reference mentions a plugin case among its 'special considerations', but I couldn't obtain nothing working till now, so that I wonder if I should use instead the 'PIMPL' idiom (mentioned in the 'Case Studies'). I'm neither sure if the PIMPL idiom is the right waym since it would imply the definition of the base class in every plugin (so in every shared object), that means a replication of the same coding. So far, is there a complete example of boost.serialization of plugins with private implementation in shared object? Many thanks in advance Giampiero

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serialization error : boost_serialization not closed
by simone pilozzi 08 Aug '12

08 Aug '12

Dear Users, I am often incurring in an error when I try to load the xml objects serialized with boost with an xml reader (notepad 2007 for example) . The error message is always the following "The following elements are not closed: boost_serialization". In the case of vector<double> the serialized file reads like this: <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="9"> <Index_values> <count>777</count> <item_version>0</item_version> <item>0.654941</item> <item>0.61598900000000001</item> <item>0.051253</item> <item>0.03968</item> ... </Index_values> Then apparently there is boost_serialization is not closed (however, the deserialization with boost will work). Am I wrong somewhere or is it truly an issue? Thanks in advance

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Compiler errors when using Boost::Spirit
by Evan Driscoll 07 Aug '12

07 Aug '12

Hey all, I'm new to Spirit and trying to put a parser together for a very simple language of S expressions. [Note: while I'm new to Spirit, I'm not new to parsers or parser combinators.] This is sort of an obnoxious email because it's basically "here, solve my problem for me even though I haven't read the docs as well as I could", but I figured I'd ask anyway; so if you take a look, I'm much appreciative. I define some tokens template <typename Lexer> struct tokens : lex::lexer<Lexer> { tokens() { this->self.add ("(", Tokens::L_Paren) (")", Tokens::R_Paren) ("\"...\"", Tokens::String_Literal) ("[0-9]+", Tokens::Integer_Literal) ("[a-zA-Z]+", Tokens::Symbol) ; } }; Then a grammar: template <typename Iterator> struct sexp_grammar : qi::grammar<Iterator, SExp::Ptr(), space_type> { qi::rule<Iterator, SExp::Ptr(), space_type> sexp; qi::rule<Iterator, vector<SExp::Ptr>(), space_type> sexp_list; sexp_grammar() : sexp_grammar::base_type(sexp) { using qi::token; using namespace Tokens; sexp_list = *sexp; sexp = token(String_Literal) | token(Integer_Literal) | token(Symbol) | (token(L_Paren) >> sexp_list >> token(R_Paren) ); } }; (SExp is a class, and SExp::Ptr is a typedef to shared_ptr<SExp>.) If I change the also tried removing the template parameters other than Iterator in the rules, and that let it compile (albeit with a warning). I get oodles of errors (compiling with GCC 4.6 with g++ -o src/parser.os -c -std=c++0x -g -Wall -Wextra -Wnon-virtual-dtor -fPIC -Iinclude src/parser.cc) which I'm not even going to try to paste into this email and you can look at pastebin instead: http://pastebin.com/R5Hk9gJ0 The full code can be seen at https://github.com/EvanED/simple_sexp/blob/master/src/parser.cc Evan

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[iostream] Problems opening large mapped_file
by Heiko Klein 07 Aug '12

07 Aug '12

Hi, I wanted to test the mapped_file_source iostream device. My code is working well with a normal file_source device and files >= 6GB. When I change the constructor to a mapped_file_source, it works still well for smaller files (e.g. 150MB), but for files > 2GB I get (tested with 2.5GB): exception occured: failed getting file size: Value too large for defined data type And for files > 4GB (tested with 6GB) I get: exception occured: failed opening file: Bad file descriptor My constructor is as follows: using namespace boost::iostreams; typedef stream<mapped_file_source> mmStream; mmStream* mmistream = new mmStream(); mmistream->open(mapped_file_source(fileName)); I've tested against boost 1.44 and a 32bit linux (Ubuntu 10.04). Are these general mmap problems, or am I missing some flags for mapped_file_source? Best regards, Heiko

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