April 2008 - Boost-users - lists.preview.boost.org

Datetime: time_of_day and time_range concept
by Jean-Pierre Bergamin 03 Apr '08

03 Apr '08

Hello everyone While implementing a job scheduler that has to start jobs at specific times (i.e. daily at 08:15) and during specific time ranges (every Monday between 16:20 and 18:00), the need for two new concepts that represents a time (detached from a date) and a time range between two time_of_day came up. While time_duration almost fits these needs, there are some things that we had to take into account: - A time_of_day must be normalized to only allow hours >= 0 && hours < 24 - Only the substract operator makes sense to calculate the duration between to times (15:30 - 12:00 = 3 hours and 30 minutes). 12:20 + 15:32 does not make sense. The implicit conversion to time_duration also allows the usage of time_of_day to create ptime instances (which is IMHO more "understandable" then using time_duration): ptime some_time(date(2008, 4, 1), time_of_day(14, 20, 0)); The implemented classes time_of_day (derived from time_duration) and time_range are very lightweight and allow the user to do things like: BOOST_AUTO_TEST_CASE( time_of_day_test2 ) { time_of_day t1(15,0,0); time_of_day t2(40,0,0); // normalized to 16:00:00 BOOST_MESSAGE("t1 " << t1); // t1 15:00:00 BOOST_MESSAGE("t2 " << t2); // t2 16:00:00 t2 += hours(3) + minutes(30); BOOST_MESSAGE("t1 " << t1); // t1 15:00:00 BOOST_MESSAGE("t2 " << t2); // t2 19:30:00 time_duration d1(t2 - t1); // Duration from 15:00 to 19:30 = 4:30 hour time_duration d2(t1 - t2); // Duration from 19:30 to 15:00 = 19:30 hours BOOST_MESSAGE("d1 " << d1); // d1 04:30:00 BOOST_MESSAGE("d2 " << d2); // d2 19:30:00 time_range afternoon(t1, t2); // From 15:00 to 19:30 time_range over_night(t2, t1); // From 19:30 to 15:00 (over midnight) ptime p1(date(2008, 4, 1), time_of_day(14, 20, 0)); ptime p2(date(2008, 4, 1), time_of_day(16, 40, 0)); BOOST_CHECK(afternoon.contains(p1) == false); BOOST_CHECK(afternoon.contains(p2) == true); BOOST_CHECK(over_night.contains(p1) == true); BOOST_CHECK(over_night.contains(p2) == false); time_range tr1(time_of_day(15, 0, 0), time_of_day(18, 0, 0)); // 15:00 to 18:00 time_range tr2(time_of_day(16, 0, 0), time_of_day(17, 0, 0)); // 16:00 to 17:00 time_range tr3(time_of_day(17, 0, 0), time_of_day(19, 0, 0)); // 17:00 to 19:00 BOOST_CHECK(tr1.contains(tr2) == true); BOOST_CHECK(tr2.contains(tr1) == false); BOOST_CHECK(tr2.contains(tr3) == false); } I think these concepts would fit well into the date time lib. What do you think? Regards James

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Re: [Boost-users] serialization, 1.34/1.35 difference: serializing a vector
by Filip Peters 03 Apr '08

03 Apr '08

I looked a bit deeper into the code and found this: in 1.34.1, a vector would use the code from collections_save_imp.hpp, which contains the following: unsigned int count = s.size(); ar << BOOST_SERIALIZATION_NVP(count); if(3 < ar.get_library_version()){ const unsigned int item_version = version< BOOST_DEDUCED_TYPENAME Container::value_type >::value; ar << BOOST_SERIALIZATION_NVP(item_version); } in 1.35.0, there is an "optimized" version in vector.hpp, const collection_size_type count(t.size()); ar << BOOST_SERIALIZATION_NVP(count); if (!t.empty()) ar << make_array(detail::get_data(t),t.size()); without the item_version. Loading a vector of a type like int or double, created in 1.34 won't work in 1.35. Filip Peters. Haven't used boost's trac before, but I'll enter it tomorrow. In the meantime, adding item_version into the optimized versions seems to solve my problem, except I have to make sure it doesn't break in the next version. ----- Original Message ---- From: Robert Ramey <ramey(a)rrsd.com> To: boost-users(a)lists.boost.org Sent: Wednesday, April 2, 2008 6:30:01 PM Subject: Re: [Boost-users] serialization, 1.34/1.35 difference: serializing a vector Hmm I don't recal where that might have come from. Open a TRAK item. Robert Ramey "Filip Peters" <filippeters(a)yahoo.com> wrote in message news:859190.51711.qm@web30705.mail.mud.yahoo.com... I just tried serializing a simple vector, std::vector<unsigned int> vectortest; If I serialize out in 1.34, I can't read it in in 1.35. xml result from 1.35: <vectortest> <count>3</count> <item>1</item> <item>2</item> <item>3</item> </vectortest> from 1.34: <vectortest> <count>3</count> <item_version>0</item_version> <item>1</item> &n bsp; <item>2</item> <item>3</item> </vectortest> Notice the item_version, this causes an exception when reading it in with 1.35.... I need a way to get the behavior from 1.34 back.... Otherwise my files aren't readable anymore. small testprogram: #include <boost/config.hpp> #include <boost/archive/xml_oarchive.hpp> #include <boost/archive/xml_iarchive.hpp> //#include <boost/archive/binary_iarchive.hpp> //#include <boost/archive/binary_oarchive.hpp> #include <boost/serialization/vector.hpp> #include <boost/serialization/export.hpp> #include <fstream> #include <iomanip> int _tmain(int argc, _TCHAR* argv[]) { std::vector<unsigned int> testvector; testvector.push_back(1.); testvector.push_back (2.); testvector.push_back(3.); //this in 1.34 std::ofstream ofs( "testing2.txt", std::ios::binary ) ; boost::archive::xml_oarchive oa(ofs); oa << boost::serialization::make_nvp("vectortest", testvector); ofs.close(); //do this in 1.35 try{ std::ifstream ofs( "testing2.txt", std::ios::binary ) ; boost::archive::xml_iarchive ia(ofs); ia >> boost::serialization::make_nvp("vectortest", testvector2); ofs.close(); } catch(boost::archi ve::archive_exception testexception){ //reading a file from 1.34, will end up here std::string error = testexception.what(); } return 0; } You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost. _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users ____________________________________________________________________________________ You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost. http://tc.deals.yahoo.com/tc/blockbuster/text5.com

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boost::iequals bug in 1.35?
by L Pocaille 03 Apr '08

03 Apr '08

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asio::async_read and buffer handling
by Axel 03 Apr '08

03 Apr '08

Hello I m a new Boost user, (and a little less but still new C++ developper) and I d like to find some advices about how to manage network communications. I m writing a daemon and I use boost::asio::async_read_until() to fill a boost::asio::streambuf buffer. Here's the corresponding handler : void Session::handleRecv(const boost::system::error_code& error, size_t size) { if(error.value() == 0 && size > 0) { size -= separator.size(); istream command_stream(&buffer_); char * command_chr = new char[size]; command_stream.read(command_chr, size); string command = command_chr; cout << "COMMAND " << command << endl; buffer_.consume(separator.size()); //doSomethingWithTheCommand(command); this->start(); } } I have some questions regarding this code. If I don't consume the full buffer_ , as soon as the this->start() is called, the handlerRecv() is called again. Is this a normal behaviour ? Is there a better way to extract the command from the buffer_ variable ? Finally how could I use an iterator of buffer_ without using an external class (like it's done in http://asio.sourceforge.net/boost_asio_1_0_0/libs/asio/doc/html/boost_asio/… , example I didn't fully understood) Thanks in advance.

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[Boost.Spirit] how to extend a grammar
by dariomt＠gmail.com 03 Apr '08

03 Apr '08

Lets say I have a simple calculator grammar like the one defined in trunk\libs\spirit\example\fundamental\calc_plain.cpp Now I would like to extend that grammar e.g. add support for sqrt() One way would be modifying the existing grammar class (patch provided) But what I would like is to create a new class that uses or inherits from the existing grammar class to provide the extended behavior. That is, I would need both the calculator and the extended_calculator classes available, and without code duplication. ¿Is this possible?

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Boost tokenizer and range support
by Florin Trofin 03 Apr '08

03 Apr '08

Hi, I've been using the boost tokenizer successfully in the past and I've been quite happy with it. I was using it with std::string as my token type, but now I need to use it differently because of performance reasons (the input string is a raw UTF8 buffer (const unsigned char*) and output is a specific UTF16 string class). So I thought: maybe I can just tokenize the unsigned char buffer in place using boost::iterator_range<const unsigned char*> as my token type. And it almost worked! With a hack: the tokenizer attempts to call assign on my TokenType but boost::iterator_range doesn't have such member function. I created a wrapper class that simply delegates to the iterator_range's assignment operator and it now works! This is great because I have no more useless string constructions: I can go directly from a raw UTF8 buffer to my output string type (UTF16 based) with only one conversion and no extra allocations! I still have the nice syntax of boost tokenizer and the maximum efficiency! I think this solution should be mentioned in the tutorial docs because it might not be obvious for everybody. Also, maybe we can eliminate the hack I did by adding an assign() to the boost range interface (this seems simpler to me than modifying the tokenizer to not call assign). Thanks for the great work you guys put into this library! Best regards, Florin.

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boost::asio async_handshake timeout using deadline_timer gets caught in loop.
by j.c. 02 Apr '08

02 Apr '08

Hi, Relevant code is bold. Thanks, j.c. /** * A TLS connection base class. */ class tls_connection_base { public: /** * Constructor * @param ios */ tls_connection_base(io_service_t & ios) : timer_(ios) , context_(ios, ssl_context_t::tlsv1_client) , socket_(ios, context_) { context_.set_verify_mode(ssl_context_t::verify_peer); try { context_.load_verify_file("ca.pem"); } catch (...) { std::cout << "tls_connection_base::tls_connection_base: " << "failed to load certificate file!" << std::endl; } } /** * Virtual Destructor */ virtual ~tls_connection_base() { // ... } /** * Performs an asyncronous connect to desired endpoint. * @param endpoint The endpoint to connect to. */ void async_connect(const stream_endpoint_t & endpoint) { endpoint_ = endpoint; socket_.lowest_layer().async_connect(endpoint, boost::bind(&tls_connection_base::handle_connect, this, boost::asio::placeholders::error) ); timer_.expires_from_now(boost::posix_time::seconds(15)); timer_.async_wait(boost::bind( &tls_connection_base::handle_timeout, this) ); } void handle_connect(const error_code_t & error) { if (!error) { socket_.async_handshake(boost::asio::ssl::stream_base::client, boost::bind(&tls_connection_base::handle_handshake, this, boost::asio::placeholders::error) ); std::cout << "tls_connection_base::handle_connect: " << "Successful connection: local_endpoint(" << socket_.lowest_layer().local_endpoint() << ")" << std::endl; } else { std::cout << "tls_connection_base::handle_connect: " << "Connect error: " << error.message() << std::endl; } } void handle_handshake(const error_code_t & error) { if (!error) { std::cout << "tls_connection_base::handle_handshake: " << "Handshake success: " << std::endl; } else { std::cout << "tls_connection_base::handle_handshake: " << "Handshake failed: " << error.message() << std::endl; } } void handle_timeout() { std::cout << "tls_connection_base::handle_timeout: " << "Connection timed out! " << std::endl; socket_.lowest_layer().close(); // If we try to re-connect here, which is fired by a asio::deadline_timer // we get caught up in a loop. // How do we do an async_connect here without it going haywire? async_connect.(endpoint_); } private: deadline_timer_t timer_; ssl_context_t context_; tls_socket_t socket_; stream_endpoint_t endpoint_; };

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[string/range] 1.34.1 -> 1.35.0 problem
by Kyle Alons 02 Apr '08

02 Apr '08

After rebuilding an app with Boost 1.35 (using Visual Studio 2008/VC9 [creating a 32-bit Unicode executable] on Windows XP SP2), some code (only in a release build) calling string_algo causes assertion failures at iterator_range.hpp lines 265 and 283 (iterator_range::begin and iterator_range::empty). The assertions are a result of calls to replace_all and istarts_with (in 2 places; each call in different functions and called multiple times from a single thread; thread data used in the calls is private to this thread). If all of these calls are removed: replace_all(<wstring variable>, L"/", L"\\"); if (istarts_with(<function returning wstring>, <function returning wstring>) return; if (istarts_with(<wstring variable>, L"www.")) <wstring variable>.erase(0, 4); the assertions do not occur. If any or all are left in, some assertions occur. When building w/ Boost 1.34.1, the original code works as expected with no assertions. Before I try to construct a repro case, does anyone have any ideas on what could be wrong? Thanks. -- --------------------- Kyle Alons http://www.kinook.com

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Serialization of a vector of variants
by Robert Wilkinson 02 Apr '08

02 Apr '08

Hello I have the following code, which compiles and runs but fails to output the elements of the vector to the XML output. #include <fstream> #include <iostream> #include <string> #include "boost/variant.hpp" #include <boost/archive/text_iarchive.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/xml_iarchive.hpp> #include <boost/archive/xml_oarchive.hpp> #include <boost/serialization/nvp.hpp> #include <boost/serialization/variant.hpp> #include <boost/serialization/vector.hpp> class my_variant { private: friend class boost::serialization::access; // When the class Archive corresponds to an output archive, the // & operator is defined similar to <<. Likewise, when the class Archive // is a type of input archive the & operator is defined similar to >>. template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & BOOST_SERIALIZATION_NVP(*this); } public: boost::variant<int,std::string> var; my_variant():var((int)0) {}; my_variant(const int & value):var(value) {} my_variant(const std::string value):var(value) {} my_variant(const char* value):var(value){} ~my_variant() {}; // make virtual if planning to use as base my_variant & operator = (const int &value) { std::cerr << "VALUE is " << value << std::endl; var = (value); std::cerr << "VAR is " << var << std::endl; return *this; } my_variant & operator = (const char* value) { std::cerr << "VALUE is " << value << std::endl; var = (value); std::cerr << "VAR is " << var << std::endl; return *this; } friend std::ostream& operator << (std::ostream & os, const my_variant &var); }; std::ostream & operator << (std::ostream & os, const my_variant &var ) { return os << var.var; } //class my_variant_vector : public std::vector<my_variant>, my_variant class my_variant_vector : public std::vector<my_variant> //class my_variant_vector : public std::vector //class my_variant_vector { private: friend class boost::serialization::access; std::vector<my_variant> my_vector; // When the class Archive corresponds to an output archive, the // & operator is defined similar to <<. Likewise, when the class Archive // is a type of input archive the & operator is defined similar to >>. template<class Archive> void serialize(Archive & ar, const unsigned int version) { // ar & boost::serialization::base_object< std::vector<my_variant> >(*this); ar & BOOST_SERIALIZATION_NVP(my_vector); // ar & BOOST_SERIALIZATION_NVP(*this); // for (unsigned int i = 0; i < my_vector.size(); ++i) // { // ar & BOOST_SERIALIZATION_NVP(my_vector[i]); // } } public: my_variant_vector() {} my_variant_vector(std::vector<my_variant> tmp) { // my_vector = tmp; for (unsigned int i = 0; i < tmp.size(); ++i) { my_vector.push_back(tmp[i]); } } virtual ~my_variant_vector() {} // void push_back(my_variant tmp) {my_vector.push_back(tmp);} // int size() {return my_vector.size();} }; int main() { //boost::variant<int,std::string> myvar; //std::vector<my_variant> myvec; my_variant_vector myvec; // const my_variant_vector & myvecref = myvec; my_variant myvar; myvar=100; myvec.push_back(myvar); std::cout << "Raw output " << myvar << std::endl; for (unsigned int i = 0; i < myvec.size(); ++i) { std::cout << "I is " << i << " and Raw output " << myvec[i] << std::endl; } std::cout << "output done" << std::endl; std::string filename; filename = "integer_variant.xml"; // save data to archive { std::ofstream ofs(filename.c_str()); assert(ofs.good()); boost::archive::xml_oarchive oa(ofs); oa << BOOST_SERIALIZATION_NVP(myvar.var); } myvar="One hundred"; myvec.push_back(myvar); std::cout << "Raw output " << myvar << std::endl; for (unsigned int i = 0; i < myvec.size(); ++i) { std::cout << "I is " << i << " and Raw output " << myvec[i] << std::endl; } filename = "string_variant.xml"; // save data to archive { std::ofstream ofs(filename.c_str()); assert(ofs.good()); boost::archive::xml_oarchive oa(ofs); oa << BOOST_SERIALIZATION_NVP(myvar.var); } std::cout << "output done" << std::endl; filename = "vector_variant.xml"; // save data to archive { std::ofstream ofs(filename.c_str()); assert(ofs.good()); boost::archive::xml_oarchive oa(ofs); // oa << BOOST_SERIALIZATION_NVP(myvecref); oa << BOOST_SERIALIZATION_NVP(myvec); } } The XML files are : bob@lapland:~/src/c++/src/testing$ cat integer_variant.xml <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="4"> <myvar.var class_id="0" tracking_level="0" version="0"> <which>0</which> <value>100</value> </myvar.var> </boost_serialization> bob@lapland:~/src/c++/src/testing$ cat string_variant.xml <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="4"> <myvar.var class_id="0" tracking_level="0" version="0"> <which>1</which> <value>One hundred</value> </myvar.var> </boost_serialization> bob@lapland:~/src/c++/src/testing$ cat vector_variant.xml <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="4"> <myvec class_id="0" tracking_level="0" version="0"> <my_vector class_id="1" tracking_level="0" version="0"> <count>0</count> <item_version>0</item_version> </my_vector> </myvec> </boost_serialization> bob@lapland:~/src/c++/src/testing$ What would I need to do to have the vector elements output in vector_variant.xml? Bob -- <hop> kb: I demand integrity and honesty in those who i do business with <hop> i know my demands are unreasonable, but a guy can dream, can't he?

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[program options] new feature
by Ovanes Markarian 02 Apr '08

02 Apr '08

Hello *! I would like to know if there is any interest to support hierarchical configuraitons in boost program options library. The idea is mainly: [Level1] Option1 Option2 Option3 [[Level2]] Option1 Option2 Option3 Access rules would be: Level1.Option1 or Level1.Level2.Option1 Sometimes it is very useful to introduce an additional level instead of putting a prefix to each option. On the other hand it might be beneficial during access. PSEUDOCODE: option_group g = parsed_options["Level1.Level2"].as<option_group>(); do_smth(g["Option1"]); With Kind Regards, Ovanes Markarian

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