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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

2 2

trim() erroring out?
by Michael Wieher 02 Apr '08

02 Apr '08

/usr/include/boost/algorithm/string/trim.hpp:366: instantiated from 'void boost::algorithm::trim(SequenceT&, const std::locale&) [with SequenceT = char*]' datad/datarequest.cpp:32: instantiated from here /usr/include/boost/algorithm/string/trim.hpp:121: error: request for member 'erase' in 'Input', which is of non-class type 'char*' .. I'm passing trim() a char * ... seems like that doesn't make it happy, though?

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Boost.Regex vs. Boost.Spirit
by Boris 02 Apr '08

02 Apr '08

Can anyone tell me why Boost.Spirit (which reuses Boost.Regex for regular expressions) works while the code below where Boost.Regex is used directly can not be compiled? std::string in = "test"; boost::wregex expr(L"test"); boost::match_results<std::string::const_iterator> what; boost::regex_search(in, what, expr); // COMPILER ERROR std::string out; boost::spirit::rxstrlit<wchar_t> expr2(L"test"); boost::spirit::parse(in.c_str(), expr2[boost::spirit::assign_a(out)]); The basic problem is of course that the regular expressions are based on wchar_t while the input string is based on char. Thus I'm not so much surprised why Boost.Regex does not work. I'm much more surprised though that my compiler (VC++ 2008) doesn't report an error with the code above which uses Boost.Spirit. I don't know why the code using Boost.Spirit compiles (is this implementation-dependent or guaranteed behavior)? It would make using regular expressions in templates much easier though as regular expressions don't seem to depend on the Char type of strings (assuming this is a feature I can rely on)? Boris

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1.35.0 - what is the correct tag in SVN?
by Andrey Tcherepanov 02 Apr '08

02 Apr '08

Hello! I am wondering by what tag or branch (besides "release") (or just version) I can retrieve exatly same snapshot that was used for 1.35.0 from Subversion? Previous releases are available by RC_* tags, so I am wondering which one is used for 1.35? As general comment - may be is a good idea to have top "branch" called "releases" and then all packaged releases under it, so it is easier to find them in one place instead of going trhough all new and old working folders under branches subtree? Thank you very much, Andrey

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Need boost's help with poor design
by Robert Dailey 02 Apr '08

02 Apr '08

Hi, Currently I'm using Boost.Signals to transfer Packet objects to subscribers. Right now my Boost.Signal looks like below: boost::signal<void (Packet const& p)> Right now Packet is the base class for several other packet types, each having the specific data a subscriber needs access to. Of course, given this design, the only way to obtain the data is to perform a downcast via static_cast or dynamic_cast: WalkPacket const& wp = static_cast<WalkPacket const&>( p ); // 'p' here is a generic Packet object. This is obviously bad design since it isn't type safe at all. It's also repetitive and tedious since each subscriber must duplicate the logic to perform the downcast. I'm wondering if there's anything in Boost you guys can suggest that I use to make this a little better. I would prefer to have a common Signal object that can take differently typed Slot objects. For example, I want to pass in a slot that looks like: "void (WalkPacket& p)" and have the signal utilize implicit conversions or something. Templates aren't even being used here because I can't find a way to fit them in, since everything is being done at runtime and not compile time. Keep this important note in mind: The type of the packet that will be dispatched to subscribers can only be known at compile time via a factory method. Data is received from the network, and that data is packed into the correct packet and returned as a Packet* base class pointer, so that we can transfer the data to subscribers through a common interface.

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boost::regex - how to do a search_rev() ?
by fxplus 02 Apr '08

02 Apr '08

Hi all, String classes usually have a search_rev() function to start search from the rightmost end. Is it possible to do such a search using boost::regex? I need to find out if a text buffer (usually of size in hundreds of MBs) has certain sequences in the end. Thanks. -- Fab Ximi

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