June 2006 - Boost-users - lists.preview.boost.org

Serialization of valarray, Problem with Text Type
by Thomas DAVID 09 Jun '06

09 Jun '06

Hi all (again), I'm able to send a valarray with the XML archive but I have a problem with the Text archive. I displayed the received size in valarray.hpp. template<class Archive, class U> void load( Archive & ar, STD::valarray<U> &t, const unsigned int file_version ) { collection_size_type count; ar >> BOOST_SERIALIZATION_NVP(count); cerr << "Received size : " << count << endl; t.resize(count); if (count) ar >> make_array(detail::get_data(t), t.size()); } I have a correct "512" with XML but I have "0" with Text. But the message received is like "0 1 0 0 512 2 2 2 2 2 ...". So it seems that the message is correctly sent. Is the valarray with text buggy or I missed something (I'm quite sure this is the second option). Regards, Thomas DAVID

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set() of dynamic_bitset is too slow.
by Bo Peng 09 Jun '06

09 Jun '06

Dear list, I am using dynamic_bitset to store a sequence of random 0/1. The program generates repeatedly 32bit random numbers and assign the result to a dynamic_bitset. for(UINT i=0; i < m_N; ++i) { if(bit == block) // generate a block { ri = rng().randInt(m_max); bit = 0; } if((ri >> bit) & 0x1) succ.set(i); bit++; } When I profile this program, I surprisingly find out that succ.set(i) uses >50% of the execution time. Is there anyway I can assign block by block to dynamic_bitset, or assign sequentially so the position of i does not have to be calculated each time? Many thanks in advance. Bo

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Help to BUILD AND INSTALL Boost Libraries
by Hemal patel 08 Jun '06

08 Jun '06

Hello!! All, I ned help for BUILDING and INSTALLING the Boost Libraries through VC++ Express Edition . I tweaked it for couple of hrs unscussefully. Here is a run down of the steps I have taken Downloaded following three packs boost_1_33_1 boost-build-2.0-m10 boost-jam-3.1.12 Changed vcvars32.bat for PATH,INCLUDE and LIB settings for Platform SDK OS Environemental variables BOOST BOOST_BUILD_PATH VC80_ROOTS VC80CMNTOOLS Use of 'bjam install' or 'bjam "-sTOOLS=vc8" install ' generates following ERRORS/MESSAGE ------------------------------------------------------------------------------------------------------------------------------------------------------------------ C:/dnld/BOOST/boost_1_33_1/tools/build/v2\build-system.jam:48: in load rule os.environ unknown in module build-system. ------------------------------------------------------------------------------------------------------------------------------------------------------------------ C:\dnld\BOOST\boost-build-2.0-m10\boost-build\kernel\modules.jam:259: in import C:\dnld\BOOST\boost-build-2.0-m10\boost-build\kernel\bootstrap.jam:120: in boost-build C:\dnld\BOOST\boost-build-2.0-m10\boost-build\boost-build.jam:1: in module scope can someone of you take a while to show pointers to correct me. Thanks for all your time. Hemal Patel

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Re: [Boost-users] [multi index].[composite key] Index creation at run-time.
by Prashant Thakre 08 Jun '06

08 Jun '06

One final suggestion :) regarding the choice of index_container in terms of performance, memory requirements, serialization support and insert/lookup opreations considering that std::vector<const std::string> will be the basis for this container : 1.Composite keys and hashed indices. 2.Hashed indices. Thanks a lot for clarifying all the doubts. -- regards, Prashant Thakre ----- Original Message ----- From: "Joaquín Mª López Muñoz" <joaquin(a)tid.es> Newsgroups: gmane.comp.lib.boost.user Sent: Thursday, June 08, 2006 6:51 PM Subject: Re: [multi index].[composite key] Index creation at run-time. Prashant Thakre ha escrito: > Hi, > > > OK, here, instead of a composite_key instantiation, > > you can take advantage directly of std::vector comparison > > semantics (you don't really need tuple_element): > > > > typedef multi_index_container< > > element, > > indexed_by< > > hashed_unique< > > member<element,std::vector<const std::string>,&element::tp> > > > > > // other indices, maybe > > > > > > element_collection; > > > > Is this equivalent to having a member std::string tp which is constructed at > run-time from all the elements of std::vector< const std::string > ? Depends on how you construct that string: if you just concatenate the vector elements, then no, it's not equivalent. For instance, the following two vectors {"mast","err","apparent"} {"master","rap","parent"} both map to "masterrapparent". > Also, how does the hash function generate the key ? Boost.Hash combines the vector element's hash values as described at http://boost.org/doc/html/id2490467.html B.MI also lets you specify your own hashing mechanism if you need it: http://boost.org/libs/multi_index/doc/advanced_topics.html#hash_spec Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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Re: [Boost-users] [multi_index].[composite_key] Index creation at run-time.
by Prashant Thakre 08 Jun '06

08 Jun '06

Hi, Guess, I should have given a code snippet :( >But, how are you planning to actually implement this? >Certainly you can't do the following: struct element { public: boost::tuple<t0,t1,...tn> tp; // ... }; As per your first suggestion: >1. If the maxium number of keys of the composite_key is bounded >then you can use that maximum and later on, at run-time, take >advantage of only the first N key slots. struct element { //Assumption: no more than 10 elements, a reasonable limit I guess. // boost::tuple<t0,t1,...t9> tp; const std::string & tuple_element(const int ind) const { return tp.get<ind>; } //... }; As per this suggestion: >2. You can have std::vector<> as the key, the comparison semantics >of this container in some ways resembles that of an infinite-length >composite key. struct element { std::vector<const std::string > tp; const std::string & tuple_element(const int ind) const { return tp[ind]; } //... }; template < std::size_t hash_table_size> struct element_hash { int operator() ( const std::string & hash_string ) const { std::string::const_iterator hash_iter = hash_string.begin(); register int hash_value = 0; //... return hash_value; } }; typedef multi_index_container< element, indexed_by< hashed_unique < // indexed by elements of tuple/vector composite_key< element, const_mem_fun< element, const std::string &, &element::tuple_element(0) > >, // end of composite key def composite_key_hash < element_hash< 8191 > > // end of key hash > // end of hash > // end of inedexed_by > > > element_collection; regards, Prashant Thakre > ----- Mensaje original ----- > De: Prashant Thakre <prashant.thakre_at_[hidden]> > Fecha: Martes, Junio 6, 2006 9:06 pm > Asunto: Re: [Boost-users] [multi_index].[composite_key] Index creation > atrun-time. > > > > Hi, > > Thanks for the reply. > > You're welcome. I'm afraid I'll have to ask > for some more info before I can try to answer > your original question, though :( > > > > This is what I am trying to achieve: > > a) Each entry in the container will have tuple containing n-elements > > tuple < t0, t1 ..., tn >, where n is known at run-time. This entry > > will also have other elements. > > > But, how are you planning to actually implement this? > Certainly you can't do the following: > > > class element > { > public: > boost::tuple<t0,t1,...tn> tp; > ... > }; > > > because you don't know n at compile time. This question > is important, since how you actually implement the > run-time knowledge of n will surely determine the way > you can plug a composite_key into the scheme. If you > can provide some actual code, no matter how sketchy, > showing how you implement your element type, so much > the better. > > > Looking fwd to your feedback, > > > Joaquín M López Muñoz > Telefónica, Investigación y Desarrollo

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Re: [Boost-users] [date_time] posix_time input/output facet symme try
by LABELLE, Maxime 08 Jun '06

08 Jun '06

Jeff Garland wrote something like: > (...) I'm afraid this is a parser bug. I've put together a fix I'd like you to try out. (...) > Download (...) time_facet.hpp and patch it into your boost/date_time/ directory. > > Thanks, > > Jeff Thanks a lot Jeff. It does indeed solve my problem. Thank you for your time. Cheers. Maxime.

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regex_search and match_results issue?
by dave＠superelite.net 08 Jun '06

08 Jun '06

Hi, im having trouble with a base case for regex_search and the number of hits it finds in a haystack. I am wondering if i am not setting flags that need to be set, but i cannot find anything for this in the docs. My usage only seems to find the string "HELLO" once, as the cout indicates xcmMatch.size() is 1 after i run this. I am using boost libs 1.31.00 . Thanks! Heres my code: string sMatchMe = "HELLO"; int theseflags=0; boost::regex xreMatchme(sMatchMe.c_str(), theseflags); boost::cmatch xcmMatch; string stupid = "sdfaHELLOdsfh*sadhfas1d3ahsdf%as&d!adfasdfsdHELLObnbc"; if(regex_search(stupid.c_str(), xcmMatch, xreMatchme)) { cout << "number of matches here should be " << xcmMatch.size() << endl; }

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delaying destructor compile on imcomplete type
by Gottlob Frege 08 Jun '06

08 Jun '06

IIRC, one of boost's smart ptrs can be used with an incomplete type. How is the compile of the destructor delayed? ie ~my_smart_ptr() { get()->~T(); // error: T is an incomplete type } I wondered through lots of the shared_ptr code, but I got a bit bleary-eyed. On that note, does anyone have a script or preprocessor call or something that converts all the boost code into the 'clean and ideal boost'? ie the one without the layers and layers of compiler workarounds, etc? I think that version would be a much easier read. And maybe some day all compilers will support that version too. We can but dream... Tony

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Re: [Boost-users] [spirit] trouble using parse function with rules
by Gabriel Redner 08 Jun '06

08 Jun '06

Sorry, fat-fingered things and the message was sent too early. trying again: Hi all, I am new to spirit, and my only source of information has been the current spirit documentation. I am running into a curious problem in which the manual suggests some code should compile, yet it does not. Test case: ---------------------------------------------------------------------------------------------- #include <boost/spirit/core.hpp> using namespace boost::spirit; int main() { const char *s = "(1)"; rule<> r = ch_p('(') >> int_p >> ch_p(')'); parse(s, r); // compiles OK parse(s, r, space_p); // does NOT compile parse(s, ch_p('(') >> int_p >> ch_p(')'), space_p); // compiles OK } ---------------------------------------------------------------------------------------------- Why does the third parse() compile, but not the second? Does the rule require some kind of adaptor to work in this context? Thanks, -Gabe

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[date_time] posix_time input/output facet symmetry
by LABELLE, Maxime 08 Jun '06

08 Jun '06

I'm experiencing a problem using custom formatting of fractional seconds. const std::string date_string = "2006 Jun 01 999000 23.59.59"; const std::string format_string = "%Y %b %d %f %H.%M.%S"; When using a time_facet together with the "%f" flag, I get a correct output containing a 6-digit number in place of the fractional part. However, using a time_input_facet together with the "%f" flag, I cannot get a correct ptime from an input using the same format as the above example. The problem is twofold : 1) First, the input facet expects a leading '.' otherwise, it parses a special value and fails. [see time_facet.hpp(1035-1049)] This is not the case in an output facet. 2) Second, even if I include a leading dot, the space after the fractional seconds is not consumed, and the parsing of the remainder fails. This means that I need to add an extra space to the input format string. Here is a sample program: --------- #include <cassert> #include <boost/posix_time/posix_time.hpp> Using namespace boost; ... posix_time::ptime time; const std::string input_format = "%Y %b %d %f %H.%M.%S"; // formats are const std::string output_format = "%Y %b %d .%f %H.%M.%S"; // not symmetric const std::string input_date_string = "2006 Jun 01 .999000 23.59.59"; std::string output_date_string; { posix_time::time_input_facet* input_facet = new posix_time::time_input_facet(input_format.c_str()); std::istringstream in(input_date_string); in.imbue(std::locale(std::locale::classic(), input_facet)); in >> time; } { posix_time::time_facet* output_facet = new posix_time::time_facet(output_format.c_str()); std::ostringstream out; out.imbue(std::locale(std::locale::classic(), output_facet)); out << time; output_date_string = out.str(); } assert( output_date_string == input_date_string ); --------- Am I missing something ? Thanks for your help. Maxime LABELLE.

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