July 2009 - Boost-users - lists.preview.boost.org

[phoenix] using dereference and increment operator
by Kim Kuen Tang 20 Jul '09

20 Jul '09

Hi all, the following piece of code compiled with boost 1.39: std::vector<double> u(11,1.0), w(11,3.0); std::vector<double>::const_iterator it=w.begin(); double value=(*ph::ref(it)++)(); But if i use the expression *ph::ref(it)++ as a functional in an algorithm, std::generate(u.begin(),u.end(),*phoenix::ref(it)++ ); the compilation fails with the following error: >c:\boost\boost_msvc_2008\include\boost-1_39\boost\fusion\container\vector\detail\vector_n.hpp(68) : error C2440: '<function-style-cast>' : cannot convert from 'const boost::phoenix::composite<EvalPolicy,EvalTuple>' to 'boost::fusion::vector_data1<Derived,T0>' 1> with 1> [ 1> EvalPolicy=boost::phoenix::post_increment_eval, 1> EvalTuple=boost::fusion::vector<boost::phoenix::reference<std::_Vector_const_iterator<double,std::allocator<double>>>,boost::fusion::void_,boost::fusion::void_,boost::fusion::void_,boost::fusion::void_,boost::fusion::void_,boost::fusion::void_,boost::fusion::void_,boost::fusion::void_,boost::fusion::void_> 1> ] 1> and 1> [ 1> Derived=boost::fusion::vector1<boost::phoenix::reference<std::_Vector_const_iterator<double,std::allocator<double>>>>, 1> T0=boost::phoenix::reference<std::_Vector_const_iterator<double,std::allocator<double>>> 1> ] 1> No constructor could take the source type, or constructor overload resolution was ambiguous I remember that the compilation was fine when using boost 1.38. ( I need to check this.) Here is the code that produces the errors: # include <algorithm> # include <vector> # include <boost/spirit/include/phoenix.hpp> using namespace boost; int main() { std::vector<double> u(11,1.0), w(11,3.0); std::vector<double>::const_iterator it=w.begin(); double value=(*phoenix::ref(it)++)(); it=w.begin(); std::generate(u.begin(),u.end(),*phoenix::ref(it)++ ); return 0; } With regards, Kim Tang

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Definition of string in shared memory
by Samuel Gallard 20 Jul '09

20 Jul '09

Hello, I can't useful examples about how to store string in shared memory. I have to share a queue of Element objects (queue<Element> *) between processes. This is the signature of Element class : class Element { ... private : string dir; string file; ... } I used a shared_memory_object to use the queue. When I test it with thread, it is working fine. But when i test it with process, I obtained some segmentation fault because it can't retrieve the attributes for an Element object. it is normal because I am creating the Element object in one process the second can't access it. I have seen in boost documentation the template interprocess:basic_string. But I have no clue how to use it. I would like to have something like : typedef basic_string< string, segment> mystring class Element { ... private : mystring dir; mystring file; ... } Could you someone show me how to do that in the creation but also in the implementation. Thanks you in advance Regards Samuel

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Locale and Boost.Serialization
by Luca Cappa 20 Jul '09

20 Jul '09

Hello, on the Windows platform, in my own application (built in unicode char econding) I am experiencing this problem with Boost 1.38: if I change the locale before loading an xml archive, then the application will hang in the loading of the archive file. I must add that this only occurs in a Release build on Windows Vista, but it never occurs on Windows XP. Also, if I run the application on Vista with the Compatibility Mode set to Windows XP SP2, it does work and does not hang while loading the archive. I tryed to get a stack trace with a ReleaseWithDebInfo on Windows Vista, here it is: Warning: stack unwind information unavailable. Following frames may be wrong. application!std::vector<double, std::allocator<double> > ::push_back+0xblabl1 application!std::vector<double, std::allocator<double> > ::push_back+0xblabl2 application!std::vector<double, std::allocator<double> > ::push_back+0xblabl3 application!boost::archive::detail::oserializer<boost::archive::xml_oarchive, boost::shared_ptr<TriggerUnit> > ::save_object_data+0x18b50 application!0xblabla Any hint what to look at to resolve this issue? Many thanks. Best Regards, Luca

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Spirit 1.39 compilation times
by Avi Bahra 20 Jul '09

20 Jul '09

I am using boost spirit 1.39. On gcc the compilation times are acceptable. However on AIX with v10.1 compiler, it fails to even compile. After 24hrs waiting, I gave up. Ok I realise that the grammer needs to split. Is there any _small_ examples out there, that demonstrates this technique for a beginner ? In my case I have one grammer and ~70 rules. Take the following rule: rule<ScannerT, string_closure::context_t> identifier ; identifier = lexeme_d [ (alnum_p || ch_p('_')) >> *(alnum_p || ch_p('_')) ] [ identifier.name = construct_<std::string>(arg1, arg2) ] ; What is the technique for converting it into a grammer, that is separately compiled ? Also how would I reference it again, without including the header file, from another rule dotPath = ( str_p(".") >> +( str_p("/") >> identifier ) ) [ dotPath.name = construct_<std::string>(arg1, arg2) ] ; Any help would greatly appreciated. Best regards, Ta, Avi

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[Asio] How do I dynamically select a port?
by Robert Jones 19 Jul '09

19 Jul '09

Hi All I'm new to Asio, and not a tcp/ip expert either, so if I'm approaching this all wrong then please tell me. I have two process on one machine, one of which streams a file to the other. In fact there may be several 'others', but one other will suffice to phrase the question. I need to dynamically select port numbers on which to stream the files to these other processes, based on whether that port number is available, and once the viability of using a particular port is established that port number can be communicated to the other process(es) by other means. So, the code sequence I have is this. At what point can I detect that use of this particular port number is ok? Is it appropriate to use from_string("127.0.0.1"), or should I use some other form for local sockets? Comments appreciated. using namespace boost; using asio :: ip :: tcp; unsigned short port = 2001; asio :: io_service io; tcp :: endpoint endpoint( asio :: ip :: address :: from_string( "127.0.0.1" ), port ); tcp :: acceptor acceptor( io, endpoint ); tcp :: iostream socket_stream; acceptor.accept( * socket_stream.rdbuf( ) ); Thanks, - Rob.

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[Regex] Some help with regular expression
by Etienne Philip Pretorius 19 Jul '09

19 Jul '09

Hello List. I have been trying to get this regular expression to work without any success. Perhaps if someone could just point out my mistake in the following regexp: /* http://www.w3.org/TR/REC-xml/#NT-PITarget */ entity grammar::process_instruction_target( std::string("(?!(X|x)(M|m)(L|l))(") + name.str() + std::string(")")); The 'name' regexp looks like this (Tested and working): /* http://www.w3.org/TR/REC-xml/#NT-Name */ entity grammar::name(std::string("(") + name_start_character.str() + std::string(")(") + name_character.str() + std::string(")*")); The others (name_start_character and name_character) are as follows (UTF8 encoding assumed): /* http://www.w3.org/TR/REC-xml/#NT-NameChar */ entity grammar::name_character(name_start_character.str() + std::string("|-|\\.|[0-9]|\\x{C2}\\x{B7}|") + std::string("\\x{CC}[\\x{80}-\\x{BF}]|") + std::string("\\x{CD}[\\x{80}-\\x{AF}]|") + std::string("\\x{E2}(\\x{80}\\x{BF})|(\\x{81}\\x{80})")); /* http://www.w3.org/TR/REC-xml/#NT-NameStartChar */ entity grammar::name_start_character( ":|[A-Z]|_|[a-z]|" "(\\x{C3}[\\x{80}-\\x{96}]|[\\x{98}-\\x{B6}]|[\\x{B8}-\\x{BF}])|" "([\\x{C4}-\\x{CB}][\\x{80}-\\x{BF}])|" "(\\x{CD}[\\x{B0}-\\x{BD}]|\\x{BF})|" "([\\x{CE}-\\x{DF}][\\x{80}-\\x{BF}])|" "(\\x{E0}[\\x{A0}-\\x{BF}][\\x{80}-\\x{BF}])|" "(\\x{E1}[\\x{80}-\\x{BF}]{2})|" "(\\x{E2}(\\x{80}[\\x{8C}-\\x{8D}])|" "(\\x{81}[\\x{B0}-\\x{BF}])|" "([\\x{82}-\\x{85}][\\x{80}-\\x{BF}])|" "(\\x{86}[\\x{80}-\\x{8F})|" "([\\x{B0}-\\x{BE}][\\x{80}-\\x{BF}])|" "(\\x{BF}[\\x{80}-\\x{AF}]))|" "([\\x{E3}-\\x{EC}][\\x{80}-\\x{BF}]{2})(?!\\x{E3}\\x{80}{2})|" "(\\x{ED}[\\x{80}-\\x{9F}][\\x{80}-\\x{BF}])|" "(\\x{EF}[\\x{A4}-\\x{B6}][\\x{80}-\\x{BF}])|" "(\\x{EF}\\x{B7}([\\x{80}-\\x{8F}]|[\\x{B0}-\\x{BF}]))|" "(\\x{EF}[\\x{B8}-\\x{BE}][\\x{80}-\\x{BF}])|" "(\\x{EF}\\x{BF}[\\x{80}-\\x{BD}])|" "(\\x{F0}[\\x{90}-\\x{BF}][\\x{80}-\\x{BF}])|" "([\\x{F1}-\\x{F2}][\\x{80}-\\x{BF}]{3})|" "(\\x{F3}[\\x{80}-\\x{AF}][\\x{80}-\\x{BF}]{2})"); Any help will be apreciated. You see the 'process_instruction_target' regexp keeps on matching for xml and any variant thereof... while it should match all except for the variants of xml. Thank you, Etienne

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enable_if catch all?
by Zachary Turner 19 Jul '09

19 Jul '09

Supposing I have 4 or 5 mutually exclusive overloads of a function using enable_if as a function parameter with a default argument, is there any way for me to provide an additional version of this function that handles every other case, without manually combining all the previous cases and using another enable_if? For example: template<class T> void foo(typename enable_if<condition1>::type* dummy=0) {} template<class T> void foo(typename enable_if<condition2>::type* dummy=0) {} template<class T> void foo(typename enable_if<condition3>::type* dummy=0) {} template<class T> void foo(typename enable_if<condition4>::type* dummy=0) {} template<class T> void foo() { //default instantiation that gets invoked if and only if all of the other overloads fail }

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[test] manual test suite initialization: linking problems
by Matthias Vallentin 19 Jul '09

19 Jul '09

I am having a linking issue with Boost.Test on my Mac OS X 10.5. Consider the following example: #define BOOST_TEST_DYN_LINK #include <boost/test/unit_test.hpp> void test() { } boost::unit_test::test_suite* init_unit_test_suite(int argc, char* argv[]) { boost::unit_test::test_suite* ts = BOOST_TEST_SUITE("test suite"); ts->add(BOOST_TEST_CASE(&test)); boost::unit_test::framework::master_test_suite().add(ts); return 0; } This does not compile with the following command: g++ test.cc -L/opt/local/lib -lboost_unit_test_framework-mt I am getting the following linker error: Undefined symbols: "_main", referenced from: start in crt1.10.5.o ld: symbol(s) not found collect2: ld returned 1 exit status It works, however, using the automatic test module definition, e.g. #define BOOST_TEST_DYN_LINK #define BOOST_TEST_MODULE foo #include <boost/test/unit_test.hpp> and works also when I remove BOOST_TEST_DYN_LINK and compile the program with the static library: g++ test.cc /opt/local/lib/libboost_unit_test_framework-mt.a But I can't get the first example code above to link. Does anyone see the problem lurking? Matthias -- Matthias Vallentin vallentin(a)icsi.berkeley.edu http://www.icir.org/matthias

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[mpl] type --> wrapper<type>
by Igor R 19 Jul '09

19 Jul '09

Hello, How to do in mpl the following: template<template<class> class wrapper, class arg> struct wrap { typedef wrapper<arg> type; }; Particularly, I've got a sequence of types, and I have to get shared_ptr's of these types. Thanks!

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Creating a managed_mapped_file
by Eli Zakashansky 19 Jul '09

19 Jul '09

Hello, I would like to create a managed_mapped_file which should contain a certain number of elements[n] of a certain size [k], therefore the required size which I would like to use is n*k (size of element * number of elements). But when the file is created [new bip::managed_mapped_file (bip::create_only, fileName, n*k);] besides the elements which I would like to placed in this file, a segment manager<http://www.boost.org/doc/libs/1_39_0/doc/html/interprocess/architecture.htm…> is also placed there and occupies an uncertain space [http://www.boost.org/doc/libs/1_39_0/doc/html/interprocess/architecture.htm…] I would like to know how much memory (size of file) shall I require in the C-tor so that my file will have enough space for n elements of size k, and be as compact as possible. Thanks in advance, Eli.

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