February 2014 - Boost-users - lists.preview.boost.org

[asio] resolver::cancel() problem
by Matthew Edwards 14 Mar '14

14 Mar '14

In my application (and a separate test program) it seems as though the cancel() function on the resolver does not work as intended. For async resolves, the cancel functionality should abort them immediately and pass an 'operation aborted' error code to the callback handler. In my tests, I will resolve an invalid domain (this causes the resolve to take a few seconds, to demonstrate the problem), sleep for 100ms, then call cancel on the resolver object. No cancelling actually occurs, and the callback is simply triggered after a few seconds with a "No host found" error code, not the expected operation aborted. Has anyone experienced this before, or know how I might be using the resolver incorrectly?

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Boost qi parser
by Uthpal Urubail 04 Mar '14

04 Mar '14

{ name = "new" sub_name = "SUBTITLE" values = { 1, 2, 3; } input_values = { 1, 2, 3; 5, 5, 6 10, 12, 3} type = input intval = 100 } Can some one help me to write the parser for the above format? I am trying something like below and this doesn’t seem to work for me. template <typename Iterator> struct keys_and_values : qi::grammar<Iterator, mapDef()> { keys_and_values() : keys_and_values::base_type(query) { using namespace qi; query = '{' >> *lit(' ') >> pair >> *(lit(' ') >> *lit(' ') >> pair) >> *lit(' ') >> '}'; pair = key >> -(*lit(' ') >> "=" >> *lit(' ') >> value); key = +char_("a-zA-Z0-9_") ; value = +char_("a-zA-Z0-9") | lexeme[('{' >> +char_("\"@+*.( , ) $ a-zA-Z0-9_ -") >> '}')] | lexeme[('"' >> +char_("\"@+*.( , ) $ a-zA-Z0-9_ -") >> '"')]; } qi::rule<Iterator, mapDef()> query; qi::rule<Iterator, std::pair<std::string, std::string>()> pair; qi::rule<Iterator, std::string()> key, value; }; Any help would be highly appriciated. Regards, UJ

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[BGL] Shared nodes on path
by Sensei 03 Mar '14

03 Mar '14

Dear all, I have a simple question about the most efficient way of finding shared nodes between a path and a graph. Let me be more explicit. I have an oriented graph G, and a very simple graph P, which is actually a simple oriented path (n0 -> n1 -> ... -> nK). I need to find *all* the possible shared paths between P and G with the same length as P. For instance, being P = n1 -> n2 -> n3 -> n4 -> n5 -> n6 we may find that the G and P share only two sub-paths n1 -> n2 -> n3 n5 -> n6 I'd like to find all sub-graphs that connect the two paths, for instance having n1 -> n2 -> n3 -> n10 -> n5 -> n6 n1 -> n2 -> n3 -> n42 -> n5 -> n6 with the constraint that the solution must be a path with the same length as P, therefore a solution as these n1 -> n2 -> n3 -> n9 -> n8 -> n5 -> n6 n1 -> n2 -> n3 -> n5 -> n6 would not be acceptable. I know I can do it manually, but I think a BGL-aware solution is quite better that a manual search :) Thanks & Cheers!

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Error compiling Boost::graph crs_graph
by Andrea Cassioli 28 Feb '14

28 Feb '14

Dear all, I have been using the compressed_sparse_row_graph quite extensively in past. Now, I am working under Linux with Boost 1.55 and I am lost trying to compile the following toy piece of code: #include <vector> #include <boost/graph/compressed_sparse_row_graph.hpp> int main() { typedef boost::compressed_sparse_row_graph<boost::directedS, boost::no_property, int> gtype; std::vector<boost::graph_traits<gtype>::edge_descriptor> edges; std::vector< int > distances; gtype graph(boost::edges_are_unsorted_t(), edges.begin(), edges.end(), distances.begin(), edges.size()); return 0; } Just compile with g++ 4.8.2 and you get In file included from /usr/include/boost/graph/detail/compressed_sparse_row_struct.hpp:33:0, from /usr/include/boost/graph/compressed_sparse_row_graph.hpp:29, from prova_icl.cpp:2: /usr/include/boost/graph/detail/histogram_sort.hpp: In instantiation of ��void boost::graph::detail::split_into_separate_coords(InputIterator, InputIterator, std::vector<Property>&, std::vector<Property>&) [with InputIterator = __gnu_cxx::__normal_iterator<boost::detail::csr_edge_descriptor<long unsigned int, long unsigned int>*, std::vector<boost::detail::csr_edge_descriptor<long unsigned int, long unsigned int> > >; VerticesSize = long unsigned int]��: /usr/include/boost/graph/compressed_sparse_row_graph.hpp:466:46: required from ��boost::compressed_sparse_row_graph<boost::directedS, VertexProperty, EdgeProperty, GraphProperty, Vertex, EdgeIndex>::compressed_sparse_row_graph(boost::edges_are_unsorted_t, InputIterator, InputIterator, EdgePropertyIterator, boost::compressed_sparse_row_graph<boost::directedS, VertexProperty, EdgeProperty, GraphProperty, Vertex, EdgeIndex>::vertices_size_type, const GraphProperty&) [with InputIterator = __gnu_cxx::__normal_iterator<boost::detail::csr_edge_descriptor<long unsigned int, long unsigned int>*, std::vector<boost::detail::csr_edge_descriptor<long unsigned int, long unsigned int> > >; EdgePropertyIterator = __gnu_cxx::__normal_iterator<int*, std::vector<int, std::allocator<int> > >; VertexProperty = boost::no_property; EdgeProperty = int; GraphProperty = boost::no_property; Vertex = long unsigned int; EdgeIndex = long unsigned int; boost::compressed_sparse_row_graph<boost::directedS, VertexProperty, EdgeProperty, GraphProperty, Vertex, EdgeIndex>::vertices_size_type = long unsigned int]�� prova_icl.cpp:14:34: required from here /usr/include/boost/graph/detail/histogram_sort.hpp:226:51: error: conversion from ��boost::detail::csr_edge_descriptor<long unsigned int, long unsigned int>�� to non-scalar type ��std::pair<long unsigned int, long unsigned int>�� requested std::pair<VerticesSize, VerticesSize> edge = *begin; What the xxx is happening? In my understanding sounds like there conversion from an edge_descriptor to a pair....Any ideas?? Best, Andrea Cassioli

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boost::optional with BOOST_FUSION_ADAPT_ADT broken?
by Andrew 28 Feb '14

28 Feb '14

There's an issue using get expressions returning optionals with BOOST_FUSION_ADAPT_ADT, demonstrated in the simplest case below. Optional<T> is trying initialize its internal T object using the attribute proxy object returned by fusion, but this can only degrade to optional<T> and not T, so the assignment fails. C++ wizard, K-Ballo, took a quick look at this in #boost and seemed to suggest it's the way op= is SFINAEd up for optional. Does anyone have a work around for this? #include <boost/optional.hpp> #include <boost/fusion/adapted/struct/adapt_struct.hpp> #include <boost/fusion/adapted/adt/adapt_adt.hpp> #include <boost/fusion/algorithm/auxiliary/copy.hpp> struct A { boost::optional<int> x; }; struct B { boost::optional<int> y; }; BOOST_FUSION_ADAPT_STRUCT(B, (boost::optional<int>, y)) BOOST_FUSION_ADAPT_ADT(A, (boost::optional<int>, boost::optional<int>, obj.x, obj.x = val)) int main() { A a; B b; // doesn't work: boost::fusion::copy (a, b); // this works: // boost::fusion::copy (b, a); }

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boost graph, Using Bundled Properties and Internal Properties at the same time
by Paolo Bolzoni 27 Feb '14

27 Feb '14

Dear list, Related to the other email of me I woud like to use the subgraphs class, but the base graph needs two internal properties: vertex_index and edge_index. However in my program I use bundled properties as suggested in this list some time ago. Now I have this problem, is possible to use internal and bundled properties in the same graph? Or can I use subgraph in another way? Your faithfully, Paolo

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Strange problem with boost/graph/subgraph.hpp
by Paolo Bolzoni 27 Feb '14

27 Feb '14

Dear list, I cannot compile a simple example using the subgraph implementation. I enclosed the code in the bottom of this email. It is quite short, but it is the whole code. It does not compile with errors from inside boost/graph/detail/adjacency_list.hpp about the impossiblity of making a reference to void. I read the subgraph documentation but I cannot understand why it does not work. Can anyone enlighten me? Your faithfully, Paolo The code: ------------------ >8 #include <boost/graph/adjacency_list.hpp> #include <boost/graph/subgraph.hpp> typedef boost::adjacency_list < boost::listS, boost::listS, boost::undirectedS > main_graph; typedef boost::subgraph <main_graph> sub_graph; typedef boost::graph_traits<sub_graph>::vertex_descriptor Bvertex; 8< ------------------

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[ASIO] Streambuf not containing full line
by Gonzalo Garramuno 27 Feb '14

27 Feb '14

I am using asio asynchronically. I have: void tcp_session::start_read() { // Set a deadline for the read operation. // input_deadline_.expires_from_now(boost::posix_time::seconds(30)); // input_deadline_.expires_at(boost::posix_time::pos_infin); // Start an asynchronous operation to read a newline-delimited message. boost::asio::async_read_until(socket(), input_buffer_, '\n', boost::bind(&tcp_session::handle_read, shared_from_this(), boost::asio::placeholders::error)); } void tcp_session::handle_read(const boost::system::error_code& ec) { if (stopped()) return; if (!ec) { // Extract the newline-delimited message from the buffer. std::string msg; std::istream is(&input_buffer_); is.exceptions( std::ifstream::failbit | std::ifstream::badbit | std::ifstream::eofbit ); try { while ( std::getline(is, msg) ) { // parse msg here (gets truncated to last 256 chars or so) std::cerr << msg << std::endl; } } catch ( const std::ios_base::failure& e ) { std::cerr << "getline failure " << e.what() << std::endl; } } My problem is that I am seeing messages that are not a full line, but a truncation of the line, as if a buffer gets full with 256 characters. I am unsure what I am doing wrong. I get a getline failure saying basic_ios::clear.

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[fusion] nth runtime element of a sequence
by MM 26 Feb '14

26 Feb '14

Hello, I just wanted to confirm there's no provided method to get the n'th element of say a fusion vector where n is known at runtime, except of handling it explicitkly with a switch case? Thanks MM

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Project link error with Wave on OSX
by Olivier Prat 26 Feb '14

26 Feb '14

I've just updated a project that was working under XCode 4 with boost 1.48 to XCode 5 and boost 1.55 (installed with MacPorts). Now I have a link error with Wave which wasn't the case before. This somehow baffles me as I thought everything was template based. I am also linking with libboost-wave.mt.a but that doesn't solve the problem. The linker errors are, among 6 others: Undefined symbols for architecture x86_64: "boost::wave::cpplexer::new_lexer_gen<__gnu_cxx::__normal_iterator<char*, std::string>, boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > >, boost::wave::cpplexer::lex_token<boost::wave::util::file_position< boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > > >::new_lexer(__gnu_cxx::__normal_iterator<char*, std::string> const&, __gnu_cxx::__normal_iterator<char*, std::string> const&, boost::wave::util::file_position<boost::wave::util::flex_string<char, std::char_traits<char>, std::allocator<char>, boost::wave::util::CowString<boost::wave::util::AllocatorStringStorage<char, std::allocator<char> >, char*> > > const&, boost::wave::language_support)", referenced from: I've tried forcing std::string as the BOOST_WAVE_STRINGTYPE, but that just changes the signatures of the undefined symbols. I fail to see what has changed and I am completely stuck. I would have understood if I had a compiler error but this is a link error. Is this something to do with the standard C++ library? For my project, C++ dialect is C++98 and the standard library is libstdc++. Thanks in advance, Olivier

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