September 2015 - Boost-users

switch_
by MM 25 Sep '15

25 Sep '15

I see Boost.Switch_ was provisionally accepted back inJan 2008. I see some doc here: http://dancinghacker.com/switch But I can't see it released in recent boost versions I need to select a type to dynamic_cast to based on a runtime index, so I would have the type in a mpl::vector, and use the switch_ to pick up the right type? I have under 20 types. in pseudo c++11: void f(std::size_t i, const T* obj) { typedef mpl::vector<T0, .... Tn> alltypes_t; const auto* drvobj = dynamic_cast<...>(obj); /// what do I set as arg of dynamic_cast } If switch_ can help, where do I get the code for it? Rds,

2 1

spirit help: segfault
by Littlefield, Tyler 25 Sep '15

25 Sep '15

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hello all: I'm getting a segfault when I run this. It looks like the debug prints, but when I debug it I just get an endless loop of backtrace. If anyone can help point me in the right direction, I'd appreciate it. I'd also appreciate, if possible any tips/tricks for cleaning up this grammar. Thanks! //code here: /*** *I-EBNF parser * *This defines a grammar for BNF. */ //Speeds up compilation times. //This is a relatively small grammar, this is useful. #define BOOST_SPIRIT_NO_PREDEFINED_TERMINALS #define BOOST_SPIRIT_QI_DEBUG #include <boost/config/warning_disable.hpp> #include <boost/spirit/include/qi.hpp> #include <boost/spirit/include/phoenix_operator.hpp> #include <boost/fusion/adapted.hpp> #include <boost/fusion/support.hpp> #include <vector> #include <string> #include <iostream> namespace Parser { namespace qi = boost::spirit::qi; namespace ascii = boost::spirit::ascii; enum class RHSType { Terminal, Identifier }; struct RHS { RHSType type; std::string value; }; struct Rule { std::string identifier; //lhs std::vector<RHS> rhs; }; } //expose our structs to fusion: BOOST_FUSION_ADAPT_STRUCT( Parser::RHS, (Parser::RHSType, type) (std::string, value) ) BOOST_FUSION_ADAPT_STRUCT( Parser::Rule, (std::string, identifier) (std::vector<Parser::RHS>, rhs) ) namespace Parser { typedef std::vector<Rule> RuleList; //our grammar definition template <typename Iterator> struct Grammar: qi::grammar<Iterator, std::list<Rule>, ascii::space_type> { Grammar(): Grammar::base_type(rules) { qi::char_type char_; letter = char_("a-zA-Z"); digit = char_('0', '9'); symbol = char_('[') | ']' | '[' | ']' | '(' | ')' | '<' | '>' | '\'' | '\"' | '=' | '|' | '.' | ',' | ';'; character = letter | digit | symbol | '_'; identifier = letter >> *(letter | digit | '_'); terminal = (char_('\'') >> character >> *character >> char_('\'')) | (char_('\"') >> character >> *character >> char_('\"')); lhs = identifier; rhs = terminal | identifier | char_('[') >> rhs >> char_(']') | char_('{') >> rhs >> char_('}') | char_('(') >> rhs >> char_(')') | rhs >> char_('|') >> rhs | rhs >> char_(',') >> rhs; rule = identifier >> char_('=') >> rhs; rules = rule >> *rule; } private: qi::rule<Iterator, char(), ascii::space_type> letter, digit, symbol, character; qi::rule<Iterator, std::string(), ascii::space_type> identifier, lhs, terminal; qi::rule<Iterator, RHS, ascii::space_type> rhs; qi::rule<Iterator, Rule, ascii::space_type> rule; qi::rule<Iterator, std::list<Rule>, ascii::space_type> rules; }; } int main() { Parser::Grammar<std::string::const_iterator> parser; boost::spirit::ascii::space_type space; std::string input; std::vector<std::string> output; bool result; while (std::getline(std::cin, input)) { if (input.empty()) { break; } std::string::const_iterator it, itEnd; it = input.begin(); itEnd = input.end(); result = phrase_parse(it, itEnd, parser, space, output); if (result && it == itEnd) { std::cout << "success" << std::endl; } } return 0; } - -- Take care, Ty twitter: @sorressean web:http://tysdomain.com pubkey: http://tysdomain.com/files/pubkey.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBAgAGBQJWBJSYAAoJEAdP60+BYxejpMwH/0EeVKIALYQOdl9esFIe9fIX JSor6vD/xn3e+L93TcsfpCSgtJiITfGgCPIURVX4FAE1Tf7PZSsd5lvQS6MgjyhQ q1EjDaAZNVt+cQhAftCoGcOPElx2aJXhNy/aTzcQqW1ui72t780GrF+MCo3tdq8p 5wIePhVbk0Gq8f3WBVGRXsKLi0hzwAPNXdHndNdYklNndKvClfHN8cwAZa5rFbMN b9eULQNtw42oT9tABAtpTfCl+tvExL3DMftXoALP5wONSv3ewjX8vNVWb5iv0XeZ yaYxLlnAGF314NgXOZKrtnXumDofnIzMDCZKxYFH+UfZfA7eFobGKOF3t/pN1JQ= =gD3u -----END PGP SIGNATURE-----

2 1

slow gunzip
by Andy C 24 Sep '15

24 Sep '15

Hi, I am trying to write a simple program which processes large gziped files as streams. However, it turns out, that for some reason reading is very slow and it takes almost 10 times more to even count single lines as compared to a Java equivalent or "gunzip -c largefile.gz | wc -l". I would like to ask experts to point out what assumption I make. The source is attached below. Thanks in advance, Andy #include <iostream> #include <fstream> #include <boost/iostreams/filtering_stream.hpp> #include <boost/iostreams/filter/gzip.hpp> int main(int argc, char** argv) { char buf[10*4096]; std::cout << argv[1] << '\n'; long c=0; std::ifstream file(argv[1], std::ios_base::in | std::ios_base::binary); file.rdbuf()->pubsetbuf(buf, 10*4096); try { boost::iostreams::filtering_istream in; in.push(boost::iostreams::gzip_decompressor()); in.push(file); for(std::string str; std::getline(in, str); ) c++; } catch(const boost::iostreams::gzip_error& e) { std::cout << e.what() << '\n'; } std::cout << c << '\n'; return 0; }

1 0

any_cast and added low-level const -> throws
by nice sw123 23 Sep '15

23 Sep '15

Hi, can anyone explain why an any_cast that adds a low-level const throws?? Example: char str[] = "a2"; boost::any ay(str); boost::any_cast<const char*>(ay); // throws, since a const is added!!! The only way to do this (without throwing), seems to be: boost::any_cast<char*>(ay); But why this mild "design deficiency"?? I call it "design deficiency", since the following is legal and works: char str2[] = "str2"; static_cast<const char *>(str2); So we should be able to add a low-level const, to make something read-only, right. Thanks for comments and explanations. n. Here's some test-code: /////// #include <iostream> #include <algorithm> #include <boost/any.hpp> int main() { char str[] = "a1"; boost::any ay(str); std::cout << "1 -- " << boost::any_cast<char *>(ay) << std::endl; strcpy(str, "a2"); /* throws!! */ //std::cout << "2 -- " << boost::any_cast<const char*>(ay) << std::endl; strcpy(str, "a3"); std::cout << "3 -- " << *boost::any_cast<char *>(&ay) << std::endl; strcpy(str, "a4"); /* segfault!! */ //std::cout << "4 -- " << *boost::any_cast<const char *>(&ay) << std::endl; char str2[] = "str2"; std::cout << "str2 -- " << static_cast<const char *>(str2) << std::endl; return 0; } ///////

1 2

Boost.Locale on Windows not building with runtime-link=static
by Thomas Ziegenhagen 23 Sep '15

23 Sep '15

Hello there, once every year or so I have to rebuilt boost for the current compiler/settings combination I work with. This time it's the following: Visual Studio 2015 32 and 64bit static linking statically linked runtime I built boost from within the VS2015 developer console using this command line: c:\projects\boost_1_59_0>.\b2 variant=debug,release link=static runtime-link=static address-model=32 --stagedir=stage32 -sICU_PATH=C:\projects\icu Works great. Except that Boost.Locale does not respect the "runtime-link=static" and builds for dynamically linked runtime instead. The build log looks like this: ...patience... ...found 19297 targets... ...updating 76 targets... common.mkdir stage32 common.mkdir stage32\lib common.copy stage32\lib\libboost_atomic-vc140-mt-sgd-1_59.lib common.copy stage32\lib\libboost_system-vc140-mt-sgd-1_59.lib common.copy stage32\lib\libboost_chrono-vc140-mt-sgd-1_59.lib common.copy stage32\lib\libboost_container-vc140-mt-sgd-1_59.lib common.copy stage32\lib\libboost_thread-vc140-mt-sgd-1_59.lib common.copy stage32\lib\libboost_context-vc140-mt-sgd-1_59.lib common.copy stage32\lib\libboost_coroutine-vc140-mt-sgd-1_59.lib common.copy stage32\lib\libboost_date_time-vc140-mt-sgd-1_59.lib common.copy stage32\lib\libboost_exception-vc140-mt-sgd-1_59.lib common.copy stage32\lib\libboost_filesystem-vc140-mt-sgd-1_59.lib common.copy stage32\lib\libboost_regex-vc140-mt-sgd-1_59.lib common.copy stage32\lib\libboost_graph-vc140-mt-sgd-1_59.lib common.copy stage32\lib\libboost_iostreams-vc140-mt-sgd-1_59.lib common.copy stage32\lib\libboost_system-vc140-mt-gd-1_59.lib common.copy stage32\lib\libboost_chrono-vc140-mt-gd-1_59.lib common.copy stage32\lib\libboost_thread-vc140-mt-gd-1_59.lib common.copy stage32\lib\libboost_locale-vc140-mt-gd-1_59.lib common.copy stage32\lib\libboost_log-vc140-mt-sgd-1_59.lib Shortened. Please note the build process working correctly up until iostreams - all libraries have a 's' in the filename, denoting the statically linked runtime. Then comes Boost.Locale. And Boost.Locale does not respect the static runtime linking and instead builds for DLL runtime. The build process therefore builds all dependencies (system, chrono, thread) again with dynamic runtime linking and then builds Boost.Locale. When I'm trying to use this setup in my game, the boost auto-linking mechanism correctly determines that Boost.Locale is required, but requires the static runtime linked version, which obviously doesn't exist. So this is a bug in the build files? Is there a simple quickfix I can apply to my local installation to be able to carry on? Should I open an issue in Trac? Thanks for your time. Bye, Thomas

3 3

Regarding property maps
by Rohith Reddy 23 Sep '15

23 Sep '15

Hi all, I have been working on a graph using boost graph library with edge properties as bundled properties.I have the following struct as my edge property, typedef struct Edge{ int id; int source; int target; float cost; float reverse_cost; } Edge; Provided that I am inserting the data correctly,how do I get a property map for each of the elements of the struct,that is a property map for id,a property map for the source and so on.And moreover I also want to know how to extract the type of property map,as it is required to pass its type to other function as a template parameter. Thanks in advance.

2 3

fatal error LNK1104 cannot open file 'boost_unit_test_framework.lib'
by Anshuman Sinha 23 Sep '15

23 Sep '15

Hi, I'm building Quantlib 16.2 and have built Boost 1.59.0 using the NuGet package in VS2013. Of the 19 projects in Quantlib, 18 are built successfully while 1 project, testsuite, fails. I am getting the error that 'boost_unit_test_framework.lib' cannot be opened. The file physically does not exist on my computer, possibly because I am using NuGet in VS2013 to install boost and it's doing the header only thing. Can you please recommend how I can solve this issue? Thanks, Amatya -- *Pretty simple neat puzzle*: Assume the earth is a perfect sphere. Show that at any given time, there exist two antipodal points with the same temperature.

2 1

problem with boost units
by Robert Ramey 23 Sep '15

23 Sep '15

the following small example fails to compile and points to error in assignment. For the life of me I can't figure why this should fail. Any help appreciated. Robert Ramey // include headers to implement output operations for quantities with units #include <iostream> #include <boost/units/io.hpp> #include <boost/units/systems/si/volume.hpp> int main(){ boost::units::si::volume fuel_capacity; fuel_capacity = 9.0f * boost::units::si::cubic_meters; ------------------^ std::cout << " " << fuel_capacity << "\n"; return 0; }

3 2

[ublas.matrix] Bug in reversed column
by Yuan Yao 20 Sep '15

20 Sep '15

Dear all, The following is a short example: ==================================================== #include <boost/numeric/ublas/matrix.hpp> #include <boost/numeric/ublas/matrix_proxy.hpp> #include <boost/range/adaptors.hpp> #include <iostream> int main() { boost::numeric::ublas::matrix<int> m(1, 2); std::cout << boost::size(column(m, 0)) << "\n"; std::cout << boost::size(column(m, 0) | boost::adaptors::reversed) << "\n"; return 0; } ==================================================== BOOST 1.59 VS 2015 outputs: 1 2147483649 CLANG on coliru outputs: 1 9223372036854775809 g++ on coliru outputs: 1 9223372036854775809

1 0

boost::interprocess mapped_file binary compatibility
by Vladimir Kotlyar 17 Sep '15

17 Sep '15

What, if anything, can be assumed about cross-platform and backwards binary compatibility of files generated using boost::ipc classes? I could not find any explicit statement in the IPC library docs. Thanks. -- View this message in context: http://boost.2283326.n4.nabble.com/boost-interprocess-mapped-file-binary-co… Sent from the Boost - Users mailing list archive at Nabble.com.

2 1