March 2010 - Boost-users - lists.boost.org

Re: [Boost-users] [Regex] Accessing match count
by ninti＠internode.on.net 10 Mar '10

10 Mar '10

The regexes in my previous post may be borked due to email client stripping stuff out. Let's just assume that regex_consonant and regex_vowel are well formed patterns. The code below seems to be getting closer. It returns a plausible count for number of matches of regex 'expression' in string 'word': string get_m(string word) { regex c("^" + regex_consonant); regex v(regex_vowel + "$"); string re = "(" + regex_vowel + "+" + regex_consonant + "+)"; regex expression(re); string replacement = ""; word = regex_replace(word, c, replacement); word = regex_replace(word, v, replacement); boost::sregex_token_iterator itr(word.begin(), word.end(), expression); boost::sregex_token_iterator end; int size = 0; for(; itr != end; ++itr) { size++; } string s; stringstream out; out << size; s = out.str(); return s; } Is boost::sregex_token_iterator the appropriate function for subsequently counting the number of matches found in a given string? Also, don't hold back on how bad this code is, I'm here to learn! Mick

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boost::timer elapsed time
by zbierak 10 Mar '10

10 Mar '10

Hi, I've been having a problem recently with boost::timer. I have the following code: #include <iostream> #include <boost/timer.hpp> int main() { boost::timer t; // (here: some initialization stuff) t.restart(); // (here: a job that takes several seconts) std::cout << "Total time: " << t.elapsed() << "s." << std::endl; } While on my windows machine it displays the correct time, when I compile it on Ubuntu, it constantly displays zero seconds, regardless how long the job really takes. Do you have any ideas why that might be happening? I'm using boost 1.40 and Ubuntu 9.04. Thanx in advance! -- View this message in context: http://old.nabble.com/boost%3A%3Atimer-elapsed-time-tp27846807p27846807.html Sent from the Boost - Users mailing list archive at Nabble.com.

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[Fusion] The very basics!
by Robert Jones 10 Mar '10

10 Mar '10

I don't mind admitting that I'm finding Fusion a struggle to get my head round; there's something about the compile time/run time duality that makes my brain hurt! So, a really basic question... When I write this, pretty much verbatim from the examples, despite there being the appearance of a loop, this is in fact a linear invocation of three calls to print::operator(), and since the fusion vector is entirely known at compile time, as all fusion types must be, regardless of how constructed, this "loop" is completely "unrolled" at compile time. Is this correct? Thanks, - Rob. #include <typeinfo> #include <iostream> #include <boost/fusion/include/sequence.hpp> #include <boost/fusion/include/algorithm.hpp> struct print { template <typename T> void operator()(T const& x) const { std::cout << x << " "; } }; int main( ) { using namespace boost::fusion; vector<int, char, std::string> stuff(1, 'x', "howdy"); for_each(stuff, print()); std::cout << std::endl; }

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Can't compile boost::asio
by Daniel V 10 Mar '10

10 Mar '10

Hi, I'm trying to compile the client example found in http://www.boost.org/doc/libs/1_42_0/doc/html/boost_asio/tutorial/tutdaytim… tutorials), but I get the following errors: g++ -o dist/Debug/GNU-MacOSX/socketclient build/Debug/GNU-MacOSX/main.o Undefined symbols: "boost::system::get_system_category()", referenced from: boost::asio::error::get_system_category() in main.o boost::system::error_code::error_code()in main.o __static_initialization_and_destruction_0(int, int)in main.o __static_initialization_and_destruction_0(int, int)in main.o "boost::system::get_generic_category()", referenced from: __static_initialization_and_destruction_0(int, int)in main.o __static_initialization_and_destruction_0(int, int)in main.o __static_initialization_and_destruction_0(int, int)in main.o ld: symbol(s) not found collect2: ld returned 1 exit status make[2]: *** [dist/Debug/GNU-MacOSX/socketclient] Error 1 make[1]: *** [.build-conf] Error 2 make: *** [.build-impl] Error 2 BUILD FAILED (exit value 2, total time: 2s) Any idea why this is failing? Thanks Dann

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[Regex] Accessing match count
by ninti＠internode.on.net 10 Mar '10

10 Mar '10

Newbie here trying to reimplement PHP's preg_match_all() function in C++. I'm rewriting a PHP class which functions as a Porter Stemmer. I seem to have the regex_replace code working nicely but am now stuck on regex_match/regex_search. I want to count the number of times a regex matches within a string. The regex attempts to match all occurrences of one+ vowels followed by one+ consonants (known as 'm' or measure, roughly equivalent to a syllable). The original PHP function is as follows: private static function m($str) { $c = '(?:[bcdfghjklmnpqrstvwxz]|(?<=[aeiou])y|^y)'; $v = '(?:[aeiou]|(?<![aeiou])y)'; $str = preg_replace("#^$c+#", '', $str); $str = preg_replace("#$v+$#", '', $str); preg_match_all("#($v+$c+)#", $str, $matches); return count($matches[1]); } So all I'm interested in here is the number of matches. I'm afraid I'm not even really sure which boost regex function I should be using, it seems like regex_search may be the correct choice as I'm not matching a whole string. This is what I've got so far: using namespace std; using namespace boost; string regex_vowel = "(?:[aeiou]|(?<![aeiou])y)"; string regex_consonant = "(?:[bcdfghjklmnpqrstvwxz]|(?<=[aeiou])y|^y)"; string get_m(string word) { regex c("^" + regex_consonant); regex v(regex_vowel + "$"); string replacement = ""; word = regex_replace(word, c, replacement); word = regex_replace(word, v, replacement); [ ... so far so good, this does the same as the first four lines of the PHP code above ... ] string re = "(" + regex_vowel + "+" + regex_consonant + "+)"; regex expression(re); string::const_iterator start, end; start = word.begin(); end = word.end(); match_results<string::const_iterator> what; match_flag_type flags = match_default | match_partial; regex_search(start, end, what, expression, flags); string thing = what[1]; int size = thing.size(); cout << what[1] << endl; string s; stringstream out; out << size; s = out.str(); return s; } This does not replicate the last two lines of PHP code above, instead returning the number of characters in a substring of sorts. So yes, I'm lost! Have tried several variations/possibilities but can't find a good example to work with. Have tried some much simpler variations they're not working either. TIA for any tips, even on which regex function I should be using. Mick

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[filesystem] basic_path as parameter
by Alex Lamaison 10 Mar '10

10 Mar '10

I'd like to use basic_path as a function parameter so that it works correctly whether a wide or narrow string is passed. template<typename T> void func(basic_path<T> file) { do thing to file } func("myfile"); func(L"myfile"); However I can't do this because basic_path has a second Traits template parameter which is not itself a template. So I tried the following workaround: template<typename T> struct traits_chooser; template<> struct traits_chooser<char*> { typedef boost::filesystem::path_traits traits; }; template<> struct traits_chooser<wchar_t*> { typedef boost::filesystem::wpath_traits traits; }; template<typename T> void func(basic_path<T, typename traits_chooser<T>::traits> file) {...} But my compiler (MSVC 2005) still can't deduce the parameter type. Does anyone know how I can get this to work? Many thanks. Alex Lamaison

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asio tcp async_read never returns
by Tom Kent 10 Mar '10

10 Mar '10

I am trying to convert some existing code to use boost's asio tcp sockets instead of our current implementation. I am able to get a very similar example (of a chat client/server) from the boost site working, but when I attempt to put the code into my own program it stops working. What I am doing: 1. Start a server process 2. The server process makes an empty socket and uses it to listen (with a tcp::acceptor) for TCP connections on a port (10010 for example) 3. Start a client process 4. Have the client process create a socket connect to the server's port 5. When the server sees a client is connecting, it starts listening for data(with async_read) on the socket and creates another empty socket to listen for another TCP connection on the port 6. When the client sees that the server has connected, it sends 100 bytes of data (with async_write) and waits for the socket to tell it the send is finished...when that happens it prints a message and shuts down 7. When the server gets notified that its has data that has been read, it prints a message and shuts down Obviously, I have greatly trimmed this code down from what I'm trying to implement, this is as small as I could make something that reproduces the problem. I'm running on windows and have a visual studio solution file you can get (http://boost.teeks99.com/BoostConnectionTest.zip) There's some memory leaks, thread safety problems, and such, but that's because I'm taking stuff out of existing code, so don't worry about them. Anyway, here's the files one header with some common stuff, a server, and a client. Connection.hpp: #ifndef CONNECTION_HPP #define CONNECTION_HPP #include <boost/system/error_code.hpp> #include <boost/asio.hpp> #include <boost/bind.hpp> class ConnectionTransfer { public: ConnectionTransfer(char* buffer, unsigned int size) : buffer_(buffer), size_(size) { } virtual ~ConnectionTransfer(void){} char* GetBuffer(){return buffer_;} unsigned int GetSize(){return size_;} virtual void CallbackForFinished() = 0; protected: char* buffer_; unsigned int size_; }; class ConnectionTransferInProgress { public: ConnectionTransferInProgress(ConnectionTransfer* ct): ct_(ct) {} ~ConnectionTransferInProgress(void){} void operator()(const boost::system::error_code& error){Other(error);} void Other(const boost::system::error_code& error){ if(!error) ct_->CallbackForFinished(); } private: ConnectionTransfer* ct_; }; class Connection { public: Connection(boost::asio::io_service& io_service): sock_(io_service) {} ~Connection(void){} void AsyncSend(ConnectionTransfer* ct){ ConnectionTransferInProgress tip(ct); //sock_->async_send(boost::asio::buffer(ct->GetBuffer(), // static_cast<std::size_t>(ct->GetSize())), tip); boost::asio::async_write(sock_, boost::asio::buffer(ct->GetBuffer(), static_cast<std::size_t>(ct->GetSize())), boost::bind( &ConnectionTransferInProgress::Other, tip, boost::asio::placeholders::error)); } void AsyncReceive(ConnectionTransfer* ct){ ConnectionTransferInProgress tip(ct); //sock_->async_receive(boost::asio::buffer(ct->GetBuffer(), // static_cast<std::size_t>(ct->GetSize())), tip); boost::asio::async_read(sock_, boost::asio::buffer(ct->GetBuffer(), static_cast<std::size_t>(ct->GetSize())), boost::bind( &ConnectionTransferInProgress::Other, tip, boost::asio::placeholders::error)); } boost::asio::ip::tcp::socket& GetSocket(){return sock_;} private: boost::asio::ip::tcp::socket sock_; }; #endif //CONNECTION_HPP BoostConnectionClient.cpp: #include "Connection.hpp" #include <boost/asio.hpp> #include <boost/bind.hpp> #include <boost/thread.hpp> #include <iostream> using namespace boost::asio::ip; bool connected; bool gotTransfer; class FakeTransfer : public ConnectionTransfer { public: FakeTransfer(char* buffer, unsigned int size) : ConnectionTransfer(buffer, size) { } void CallbackForFinished() { gotTransfer = true; } }; void ConnectHandler(const boost::system::error_code& error) { if(!error) connected = true; } int main(int argc, char* argv[]) { connected = false; gotTransfer = false; boost::asio::io_service io_service; Connection* conn = new Connection(io_service); tcp::endpoint ep(address::from_string("127.0.0.1"), 10011); conn->GetSocket().async_connect(ep, ConnectHandler); boost::thread t(boost::bind(&boost::asio::io_service::run, &io_service)); while(!connected) { boost::this_thread::sleep(boost::posix_time::millisec(1)); } std::cout << "Connected\n"; char data[100]; FakeTransfer* ft = new FakeTransfer(data, 100); conn->AsyncReceive(ft); while(!gotTransfer) { boost::this_thread::sleep(boost::posix_time::millisec(1)); } std::cout << "Done\n"; return 0; } BoostConnectionServer.cpp: #include "Connection.hpp" #include <boost/asio.hpp> #include <boost/bind.hpp> #include <boost/thread.hpp> #include <iostream> using namespace boost::asio::ip; Connection* conn1; bool conn1Done; bool gotTransfer; Connection* conn2; class FakeAcceptor { public: FakeAcceptor(boost::asio::io_service& io_service, const tcp::endpoint& endpoint) : io_service_(io_service), acceptor_(io_service, endpoint) { conn1 = new Connection(io_service_); acceptor_.async_accept(conn1->GetSocket(), boost::bind(&FakeAcceptor::HandleAccept, this, conn1, boost::asio::placeholders::error)); } void HandleAccept(Connection* conn, const boost::system::error_code& error) { if(conn == conn1) conn1Done = true; conn2 = new Connection(io_service_); acceptor_.async_accept(conn2->GetSocket(), boost::bind(&FakeAcceptor::HandleAccept, this, conn2, boost::asio::placeholders::error)); } boost::asio::io_service& io_service_; tcp::acceptor acceptor_; }; class FakeTransfer : public ConnectionTransfer { public: FakeTransfer(char* buffer, unsigned int size) : ConnectionTransfer(buffer, size) { } void CallbackForFinished() { gotTransfer = true; } }; int main(int argc, char* argv[]) { boost::asio::io_service io_service; conn1Done = false; gotTransfer = false; tcp::endpoint endpoint(tcp::v4(), 10011); FakeAcceptor fa(io_service, endpoint); boost::thread t(boost::bind(&boost::asio::io_service::run, &io_service)); while(!conn1Done) { boost::this_thread::sleep(boost::posix_time::millisec(1)); } std::cout << "Accepted incoming connection\n"; char data[100]; FakeTransfer* ft = new FakeTransfer(data, 100); conn1->AsyncReceive(ft); while(!gotTransfer) { boost::this_thread::sleep(boost::posix_time::millisec(1)); } std::cout << "Success!\n"; return 0; } I've searched around a bit, but haven't had much luck. As far as I can tell, I'm almost exactly matching the sample, so it must be something small that I'm overlooking. Any help is much appreciated! Tom P.S. cross posted to stack overflow: http://stackoverflow.com/questions/2412520/

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problem with gather array
by alev mutlu 09 Mar '10

09 Mar '10

Hi I am trying to scatter some values to workers and then gather them. But I get strange error in gather step. Any suggestions? Below is the code and error file. //mpicxx test-boost.cpp -o test-boost -I /home1/mutlu/boost/include/boost-1_37/ /home1/mutlu/boost/lib/libboost_mpi-gcc41-mt-1_37.a #include <boost/mpi/environment.hpp> #include <boost/mpi/communicator.hpp> #include <boost/mpi/collectives.hpp> #include <boost/thread/mutex.hpp> #include <iostream> #include <vector> #define MASTER 0 namespace mpi = boost::mpi; using namespace std; struct x{ string name; int age; }; int arraySize = 23; void silly_func(int *px, int sz){ for(int i = 0; i < sz; i++) px[i] = 100; } int main(int argc, char* argv[]) { mpi::environment env(argc, argv); mpi::communicator world; int m_mySize, w_mySize, kk,i; int *myValues; vector<int> a; vector<int> aa; for(int i = 0; i < arraySize; i++) a.push_back(i); w_mySize = arraySize / world.size(); if (world.rank() == MASTER){ m_mySize = arraySize / world.size() + arraySize % world.size(); myValues = (int *) malloc(m_mySize); } else{ myValues = (int *) malloc(w_mySize); } if (world.rank() == MASTER) scatter(world, a, myValues, w_mySize, 0); else scatter(world, a, myValues, w_mySize, 0); if (world.rank() == MASTER) // append the remaining elements { for (i = w_mySize * world.size(), kk = 0; i < arraySize; i++, kk++) myValues[w_mySize + kk] = a[w_mySize * world.size() + kk]; } cout << "my rank is " << world.rank() << " and my values are" << endl; if (world.rank() == MASTER) for (int i = 0; i < m_mySize; i++) cout << myValues[i] << endl; if (world.rank() != MASTER) for (int i = 0; i < w_mySize; i++) cout << myValues[i] << endl; if (world.rank() != MASTER) silly_func(myValues, w_mySize); else silly_func(myValues, m_mySize); if (world.rank() == MASTER) gather(world, myValues, m_mySize, aa, 0); else gather(world, myValues, w_mySize, aa, 0); if (world.rank() == MASTER){ cout << "======================="<< endl; for(int i = 0; i < aa.size(); i++) cout << aa[i] << endl; } } and error file is [ceng3:23784] *** Process received signal *** [ceng3:23784] Signal: Segmentation fault (11) [ceng3:23784] Signal code: Address not mapped (1) [ceng3:23784] Failing at address: (nil) [ceng3:23784] [ 0] /lib64/libpthread.so.0 [0x30e100de80] [ceng3:23784] [ 1] /lib64/libc.so.6(memcpy+0x37) [0x30e047a107] [ceng3:23784] [ 2] /usr/mpi/gcc/openmpi-1.2.8/lib64/libmpi.so.0(ompi_ddt_copy_content_same_ddt+0xe8) [0x2b180e3b5618] [ceng3:23784] [ 3] /usr/mpi/gcc/openmpi-1.2.8/lib64/libmpi.so.0(ompi_ddt_sndrcv+0x3f3) [0x2b180e3b3ef3] [ceng3:23784] [ 4] /usr/mpi/gcc/openmpi-1.2.8/lib64/openmpi/mca_coll_basic.so(mca_coll_basic_gather_intra+0xd2) [0x2b18142f20a2] [ceng3:23784] [ 5] /usr/mpi/gcc/openmpi-1.2.8/lib64/libmpi.so.0(PMPI_Gather+0x19b) [0x2b180e3c7ccb] [ceng3:23784] [ 6] test-boost(_ZN5boost3mpi6detail11gather_implIiEEvRKNS0_12communicatorEPKT_iPS6_iN4mpl_5bool_ILb1EEE+0x6b) [0x414b29] [ceng3:23784] [ 7] test-boost(_ZN5boost3mpi6gatherIiEEvRKNS0_12communicatorEPKT_iPS5_i+0x50) [0x414c82] [ceng3:23784] [ 8] test-boost(_ZN5boost3mpi6gatherIiEEvRKNS0_12communicatorEPKT_iRSt6vectorIS5_SaIS5_EEi+0x42) [0x414ce8] [ceng3:23784] [ 9] test-boost(main+0x342) [0x40f62c] [ceng3:23784] [10] /lib64/libc.so.6(__libc_start_main+0xf4) [0x30e041d8b4] [ceng3:23784] [11] test-boost(__gxx_personality_v0+0x141) [0x40f199] [ceng3:23784] *** End of error message *** mpirun noticed that job rank 0 with PID 23784 on node ceng3-ib exited on signal 11 (Segmentation fault).

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[iostreams] State of a filtering stream
by Nicola 09 Mar '10

09 Mar '10

Hi, I have implemented a filtering stream for decompressing bzipped files, which looks as shown at the end of the message. I have tried to use it like this: bz2istream bzippedfile("myfile.bz2"); while (bzippedfile >> data) { // process data } but the program enters an endless loop. The only way I can test for the end of file is with: while (bzippedfile.peek() != EOF) { bzippedfile >> data; // process data } Isn't the first method supposed to work? Is my class missing something? Regards Nicola class bz2istream : public boost::iostreams::filtering_stream<boost::iostreams::input> { public: bz2istream(std::string const& path) : ff_(path.c_str(), std::ios_base::in | std::ios_base::binary) { if (ff_.fail()) { // Here we are not distinguishing failbit from badbit... setstate(std::ios_base::failbit); } else { push(boost::iostreams::bzip2_decompressor()); push(ff_); } } private: std::ifstream ff_; };

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Skipper in rules (Spirit)
by Xavier Pegenaute 09 Mar '10

09 Mar '10

Hi, I am trying to create some rule to parse some words until the end of line. To do it I thought to use a phrase_parser and put in the SkipT parameter something like "space - eol". The problem is that seems the SkipT parameter only accepts the space rule. error: no match for call to ‘.... const boost::spirit::qi::difference<boost::spirit::qi::char_class<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, boost::spirit::qi::eol_parser> note: candidates are: .... const boost::spirit::qi::char_class<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> > In the classic spirit I know it was possible to define. May be I should change the point of view for this new version? how I should deal with it? Thanks & Regards. Xavi.

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