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

BoostCon 2009: Call for Participation
by Hartmut Kaiser 15 Dec '08

15 Dec '08

Hi all, before we all relax into the holidays I wanted to remind you all about next year's Boost Conference in Aspen, CO, USA, May 3-9. Even if all important dates are listed in the attached Call for Participation, I'll list them here once again: Proposals for submissions due: January 10th 2009. Proposals acceptances sent (tentative program available): February 10th, 2009 Fully scheduled program available: March 1st, 2009 Session materials due: April 1st 2009. IOW, you might want to use some of your free time during the next weeks to think about a possible contribution. It really doesn't take much time to come up with a short abstract! Let's make sure BoostCon 2009 will be a major C++ event! Happy holidays! Regards Hartmut Program Committee Chair BoostCon 2009

3 4

Buffering and ASIO
by Vadim Shmelev 15 Dec '08

15 Dec '08

Good day. I'm trying to read video data transferred by HTTP. I use the following function in order to read HTTP header: boost::asio::async_read_until(m_socket, m_headerBuffer, "\r\n\r\n", boost::bind(&CAXISParser::read_header, this, boost::asio::placeholders::error,boost::asio::placeholders::bytes_transferred)); , where m_headerBuffer is asio::streambuf object. During header parsing i can get video sample length. Now I want to read all video data in one function call, for example: boost::asio::async_read(m_socket, boost::asio::buffer(pSample->GetBody(), m_currentSampleLength),boost::bind(&CAXISParser::read_body, this, pSample, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); , where pSample is object with buffer for video data. There is problem that async_read_until captures some data from video data, and that call's behavior is incorrect. How can i fight that problem? For example, how can i figure out number of bytes left in streambuf and copy them to my buffer, and then read rest with async_read? I'm will very appreciate for any advices. Thanks in advance, Vadim

2 2

Fast XML Parser
by Jeff Dunlap 15 Dec '08

15 Dec '08

I've been looking at a bunch of C++ libraries for parsing XML and RapidXML looks very interesting to me. They have some very impressive benchmarks on their site due to it being a in-situ parser: http://rapidxml.sourceforge.net/ (way faster than most other XML parsers). I think that this is something that can be most useful for many of us. I know that existing boost libs can get this done but probably more complex than an exclusive lib for XML parsing. Anyway, I cannot find samples anywhere and I am not experienced enough to know how to use the lib. This is working code that I have so far (important comments include): #include "../test_utils.hpp" #include "../../rapidxml.hpp" #include "../../rapidxml_utils.hpp" #include "../../rapidxml_print.hpp" #include <string> #include <vector> #include <fstream> #include <stdexcept> #include <cstring> #include <sstream> using namespace std; void test() { char xml[] = "<?xml version=\"1.0\" encoding=\"latin-1\"?>" "<book>" "</book>"; //Parse the original document rapidxml::xml_document<> doc; // character type defaults to char doc.parse<0>(xml); // 0 means default parse flags // doc object is now a root of DOM tree containing representation of the parsed XML. // Because all RapidXml interface is contained inside namespace rapidxml, users must either bring contents of this namespace into scope, or fully qualify all the names. // Class xml_document represents a root of the DOM hierarchy. By means of public inheritance, it is also an xml_node and a memory_pool. // Template parameter of xml_document::parse() function is used to specify parsing flags, with which you can fine-tune behaviour of the parser. // Note that flags must be a compile-time constant. // To access the DOM tree, use methods of xml_node and xml_attribute classes: std::cout << "Name of my first node is: " << doc.first_node()->name() << "\n"; // Name of my first node is: book // This works but is less descriptive than 'Create proper node type' below //rapidxml::xml_node<> *node; // Create proper node type rapidxml::xml_node<char> *node = 0; node = doc.allocate_node(/*rapidxml::node_declaration*/ rapidxml::node_element, "author", "John Doe"); doc.first_node()->append_node(node); node = doc.allocate_node(rapidxml::node_element, "author", "Jane Doe"); doc.first_node()->append_node(node); node = doc.allocate_node(rapidxml::node_element, "author", "Bob Doe"); doc.first_node()->append_node(node); std::stringstream ss; ss << *doc.first_node(); std::string result_xml = ss.str(); std::cout <<result_xml<<std::endl; } int main() { test(); return 0; } I just don't have the skill to figure out how to use this. If anyone can provide some beginner snippets on how to use this library, it would be much appreciated. Idiot proof snippets on how to add, edit, delete with comments would be awsome. Thank you -- ELKNews FREE Edition - Empower your News Reader! http://www.atozedsoftware.com

4 5

linking error while using Boost-regex and Stlport in the same project
by ashish 15 Dec '08

15 Dec '08

> Hi, I'm working on a project which needs both boost-regex, and STLPORT. When these two libraries are used individually for some sample examples, they work fine. But when used both in the same project, I get linking errors as follows: >______________________________________________________________________ main/main.cpp:6: instantiated from here /home/kpendyal/software/STLport-5.1.5/stlport/stl/_algobase.c:374: warning: unused parameter '__comp2' /usr/bin/ld: warning: libstdc++.so.5, needed by /home/kpendyal/software/xerces-c_2_8_0/lib/libxerces-c.so, may conflict with libstdc++.so.6 main/main.o(.gnu.linkonce.t._ZN5boost9re_detail12perl_matcherIPKcN8stlp_ std9allocatorINS_9sub_matchIS3_EEEENS_12regex_traitsIcNS_16cpp_regex_ traitsIcEEEEE11match_matchEv+0xa3): In function `boost::re_detail::perl_matcher<char const*, stlp_std::allocator<boost::sub_match<char const*> >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::match_match()': : undefined reference to `boost::match_results<char const*, stlp_std::allocator<boost::sub_match<char const*> > >::maybe_assign(boost::match_results<char const*, stlp_std::allocator<boost::sub_match<char const*> > > const&)' main/main.o(.gnu.linkonce.t._ZN5boost12regex_searchIPKcN8stlp_ std9allocatorINS_9sub_matchIS2_EEEEcNS_12regex_traitsIcNS_16cpp_ regex_traitsIcEEEEEEbT_SC_RNS_13match_resultsISC_T0_EERKNS_11basic_ regexIT1_T2_EENS_15regex_constants12_match_flagsESC_+0x8e): In function `bool boost::regex_search<char const*, stlp_std::allocator<boost::sub_match<char const*> >, char, boost::regex_traits<char, boost::cpp_regex_ traits<char> > >(char const*, char const*, boost::match_results<char const*, stlp_std::allocator<boost::sub_match<char const*> > >&, boost::basic_ regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags, char const*)': : undefined reference to `boost::re_detail::perl_matcher<char const*, stlp_std::allocator<boost::sub_match<char const*> >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::construct_init(boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags)' main/main.o(.gnu.linkonce.t._ZN5boost9re_detail11raise_errorINS_ 20regex_traits_wrapperINS_12regex_traitsIcNS_16cpp_regex_ traitsIcEEEEEEEEvRKT_NS_15regex_constants10error_typeE+0xa3): In function `void boost::re_detail::raise_error<boost::regex_traits_wrapper<boost::regex_ traits<char, boost::cpp_regex_traits<char> > > >(boost::regex_traits_wrapper<boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::error _type)': : undefined reference to `boost::re_detail::raise_runtime_error(stlp_std::runtime _error const&)' main/main.o(.gnu.linkonce.t._ZN5boost9re_detail18basic_regex _parserIcNS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEE4failENS_ 15regex_constants10error_typeEi+0x108): In function `boost::re_detail::basic_regex_parser<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::fail(boost::regex_constants::error_type, int)': : undefined reference to `boost::regex_error::regex_error(stlp_std::basic_string<char, stlp_std::char_traits<char>, stlp_std::allocator<char> > const&, boost::regex_constants::error_type, int)' collect2: ld returned 1 exit status make: *** [ctoolkit] Error 1 ______________________________________________________________________ > > I tried to build boost with STLPORT, but never could get the library with '-p' in it's name, which I suppose is required here. How can I get it, or is there some other way???? Please help asap... >

4 8

[thread] targetting win32 in cygwin/mingw
by JOAQUIN M. LOPEZ MUÑOZ 15 Dec '08

15 Dec '08

Hi, We're having some problems in the Boost testing lists setting up a mingw environment to target Win32 when building Boost.Thread, please see the thread starting at: http://lists.boost.org/boost-testing/2008/12/6068.php Is there any documented (or undocumented) way to do this? We've been playing with DBOOST_THREAD_WIN32 and BOOST_HAS_WINTHREADS to no avail. Thank you, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

2 1

Meaning of or_<> with empty arguments
by Reetesh Mukul 15 Dec '08

15 Dec '08

Hi, This code compiles:- #include <boost/mpl/or.hpp> using boost::mpl; int main() { typedef boost::mpl::or_<> A; A a; } What is the meaning an empty or_<> ? On my gcc compiler I can see that there is no type/value inside A. With Regards, Reetesh Mukul

2 3

[Regex] problems compiling with gcc 4.4
by Aonghus Lawlor 14 Dec '08

14 Dec '08

Hi, I am using boost 1.37 on osx from macports and I have a problem using the regex library with gcc 4.4, although it seems to work perfectly with gcc 4.3 and 4.2. The problem is with creating a boost::regex object- simple program below: #include <boost/regex.hpp> #include <string> int main(int argc, char **argv) { std::string s("(.*)bar|(.*)bah"); boost::regex re_node(s); return 1; } The backtrace it produces is below: (gdb) bt #0 0x90d90b9e in __kill () #1 0x90d90b91 in kill$UNIX2003 () #2 0x90e07ec2 in raise () #3 0x90e1747f in abort () #4 0x0026792c in __gnu_cxx::__verbose_terminate_handler () #5 0x00265239 in __cxxabiv1::__terminate () #6 0x0026527d in std::terminate () #7 0x0026539c in __cxa_throw () #8 0x001eeb00 in std::__throw_bad_cast () #9 0x00370d25 in std::use_facet<std::messages<char> > () #10 0x00127c93 in boost::re_detail::cpp_regex_traits_base<char>::imbue () at cpp_regex_traits.hpp:215 #11 regex_data [inlined] () at basic_regex.hpp:173 #12 basic_regex_implementation (this=0x500200) at cpp_regex_traits.hpp:93 #13 0x001256a6 in shared_ptr<boost::re_detail::basic_regex_implementation<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > > [inlined] () at shared_ptr.hpp:525 #14 boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::do_assign (this=0xbfffe790, p1=0x5001ec "(.*)bar|(.*)bah", p2=0x5001fb "", f=0) at basic_regex.hpp:525 #15 0x00001d6a in boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::assign () #16 0x00001d3e in boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::assign<std::char_traits<char>, std::allocator<char> > () #17 0x00001c9f in boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::basic_regex<std::char_traits<char>, std::allocator<char> > () #18 0x00001b20 in main () (gdb) Is this a problem with boost, or with the compiler? Any ideas for a fix? many thanks, a

3 5

Re: [Boost-users] [boost] [review][constrained_value] compile-time lambdas
by Gordon Woodhull 14 Dec '08

14 Dec '08

>> I guess we have to wait for decltype to be able to use lambda >> expressions as predicates here? > > Why? There are already examples with lambda predicates in the docs. Yes, constrained_value does support lambdas at runtime using runtime boost::function. I was hoping that we will also be possible to specify lambdas at compile time, which is more efficient because boost::function incurs cost equivalent to a virtual method call (it prohibits inlining and dereferences a pointer). And there is the cost of storing the function pointer too... I am imagining things like constrained_value<int, decltype(_1>0 && ! bind(isnan,_1))>. In my perfect imaginary world this would be a zero-size predicate which is default constructable because it carries no data. Thus the expression doesn't need to be duplicated on construction and is stored entirely in the constrained_value typedef. 0 might have to be construct<mpl::integral_c<0> >() :-D I'm sure there are 1000 things wrong with this, just fantasizing... I guess this also falls into the bin of "what's the perfect predicate library?"

3 2

Confused with Lambda library usage
by QPlace 14 Dec '08

14 Dec '08

Cannot figure out how to properly use lambda library in following situation (pseudo-code below): class Unit { }; class Test { public: void dosmth(Unit* unit) {} }; int main() { vector<Unit*> lst; Test t; for_each (lst.begin(), lst.end(), ?// I want to call t.dosmth with each Unit* in list } Any help will be greatly appreciated.

3 5

Sobol generator
by Laurent GIORELLO 13 Dec '08

13 Dec '08

Hi all, In GSL, we can find an implementation for the sobol distribution (quasi monte carlo). Maybe we could insert this into Boost. Cheers, Laurent

1 0