October 2011 - Boost-users - lists.boost.org

How efficient is the boost::regex library?
by Alec Taylor 28 Oct '11

28 Oct '11

Good afternoon, I am looking for the most efficient open-source C++ regex library. Reading this article: http://swtch.com/~rsc/regexp/regexp1.html - It seems that GNU awk is the best overall: http://pdos.csail.mit.edu/~rsc/regexp-img/grep1p.png How does the boost::regex library compare? Would you recommend boost::regex as the most efficient one, or would you suggest another? Thanks for all information, Alec Taylor

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[serialization] tracking objects
by Matthias Brantner 28 Oct '11

28 Oct '11

Hello, I have n objects sharing common (sub)objects in a pool (i.e. via pointers). I would like to save (serialize) these n objects separately. Each result should contain one copy of the shared object and can be used stand alone. However, when loading (deserializing) multiple of those n objects, I would like to recreate the original state, i.e. subobjects previously pooled are again shared and contained in the pool. For example, object O1 contains a pointer to object P1. Object O2 also contains a pointer to object P1. O1 and O2 are separately serialized and each serialization will contain a copy of P1. After deserializing, the deserialized versions of O1 and O2 should both contain pointers to the same object P1. My current idea is to deserialize P1 (in the process of deserializing O1 or O2) by implementing the load function for P1's class. In this function, I would like to check if an object equal to P1 already exists in the pool. If it exists, I would like to return a pointer to the existing object. Otherwise, I would like to insert it into the pool and return the newly created object. However, I have not found a way to return a pointer that was not created by boost. Is there such a way or is there a better way to do what I'm trying to do? Thanks in advance. Best regards Matthias

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Boost 1.47 and exception_ptr
by Travis Gockel 28 Oct '11

28 Oct '11

I'm working on upgrading from Boost 1.46.1 to 1.47 and having one tiny little problem with exception_ptr. Currently, some of my systems keep an exception_ptr around to denote if they have a "current exception" or not. At times, we need to "clear" the current exception (it was resolved or whatever), which we used to do by calling ex->reset(). However, as of 1.47, excecption_ptr is no longer just a shared_ptr, so reset() has gone away. What is the new preferred way of getting this old functionality? I can't seem to find the way in the source. -- Travis Gockel C++ Pirate

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Event system using signals2
by Chris Cranford 28 Oct '11

28 Oct '11

In the past, I have typically seen a lot of event systems leverage an abstract base listener class that all classes were derived from if they wanted to wire themselves up to a particular system, such as an event dispatcher. This lead to giant switch statements inside the listener's handle event method. I've used this methodology in the past and it has worked. But noticing that a number of articles have suggested using a signal/slot mechanism rather than the above approach, I started trying to implement a simple event dispatcher based on boost signals2; however I cannot seem to make it work as I would like. See code below: // holds relationship of type and signal object struct event_signal { int type; boost::signals2::signal<void(void)> sig; }; typedef struct event_signal event_signal_t; class EventDispatcher { // other stuff left out public: void addListener(int type, boost::function<void(void)> pFunction) { std::map<int,even_signal_t*>::iterator i = m_events.begin(); if(i == m_events.end()) { event_signal_t* p = new event_signal_t; p->type = type; p->sig.connect(p); m_events.insert(std::make_pair(type, p)); } else { m_events[type]->sig.connect(pFunction); } } private: std::map<int, event_signal_t*> m_events; }; Since signals are not copyable, I had to store a pointer to a signal. I chose a struct in case I want to add more information later; however I could have easily used the signal directly. The classes that I want to wire to my event dispatcher must derive from boost::signals2::trackable because I want their connection to be automatically deleted upon the tracked object's destruction; so here is my tracked object: // base class for event system tracking class EventTrackedObject : public boost::signal2::trackable { public: EventTrackedObject() { } ~EventTrackedObject() { } }; class MyObject : public EventTrackedObject { public: MyObject(EventDispatcher* pDispatcher) { pDispatcher->addListener(E_MY_EVENT, boost::bind(&MyObject::OnMyEvent, this)); } ~MyObject() { } void OnMyEvent(void) { } }; The problem with this I found is that the tracked object appears to be getting copied at the time the boost::bind is passing itself to the addListener() method. Is there a way to avoid this so that the tracked object's disconnect happens as expected? Secondly, I would prefer not to have to reference this and use the bind call at all in my base objects and rather simply have a call that looks like: pDispatcher->addListener(E_MY_EVENT, &MyObject::OnMyEvent); Or is there a more ideal approach to my problem that I am missing? Chris

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Problem compiling
by Matteo 28 Oct '11

28 Oct '11

Hi guys, I am writing a class that include gboy's libraries ( http://gobysoft.com/#/software/goby) but I have a problem with boost libraries. The code is: (from gobymodule.cc) void GobyModule::start() { // // 1. Create and initialize MMDriver // // goby::acomms::ModemDriverBase* driver = 0; goby::acomms::protobuf::DriverConfig cfg; // set the serial port given on the command line cfg.set_serial_port(serial_path); using google::protobuf::uint32; // set the source id of this modem // uint32 our_id = goby::util::as<uint32>(argv[2]); cfg.set_modem_id(ID); goby::glog.set_name("WHIO Micromodem"); goby::glog.add_stream(goby::util::logger::DEBUG1, &std::clog); // default to WHOI MicroModem // if (!driver) // { std::cout << "Starting WHOI Micro-Modem MMDriver" << std::endl; driver = new goby::acomms::MMDriver; // turn data quality factor message on // (example of setting NVRAM configuration) cfg.AddExtension(micromodem::protobuf::Config::nvram_cfg, "DQF,1"); // } /////////////////////////////////////// // THE PROBLEM IS HERE ///////////////////////////////////// function_pointer = &handle_data_receive; goby::acomms::connect(&driver->signal_receive, function_pointer); // // 2. Startup the driver // driver->startup(cfg); } (from gobyModule.h) class GobyModule: { public: void function(str::string); } void (*function_pointer)(const goby::acomms::protobuf::ModemTransmission & data_msg, GobyModule* foo); void handle_data_receive(const goby::acomms::protobuf::ModemTransmission & data_msg, GobyModule* foo) { foo->payload_parser(str.str()); } The problem, compiling, is: In file included from /usr/include/boost/function/detail/maybe_include.hpp:18:0, from /usr/include/boost/function/detail/function_iterate.hpp:14, from /usr/include/boost/preprocessor/iteration/detail/iter/forward1.hpp:52, from /usr/include/boost/function.hpp:64, from /usr/include/boost/thread/future.hpp:20, from /usr/include/boost/thread.hpp:24, from /usr/local/include/goby/acomms/modemdriver/driver_base.h:23, from /usr/local/include/goby/acomms/modem_driver.h:23, from gobyModule.h:10, from gobyModule.cc:1: /usr/include/boost/function/function_template.hpp:913:60: instantiated from ‘void boost::function1<R, T1>::assign_to(Functor) [with Functor = void (*)(const goby::acomms::protobuf::ModemTransmission&, GobyModule*), R = void, T0 = const goby::acomms::protobuf::ModemTransmission&]’ /usr/include/boost/function/function_template.hpp:722:7: instantiated from ‘boost::function1<R, T1>::function1(Functor, typename boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, int>::type) [with Functor = void (*)(const goby::acomms::protobuf::ModemTransmission&, GobyModule*), R = void, T0 = const goby::acomms::protobuf::ModemTransmission&, typename boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, int>::type = int]’ /usr/include/boost/function/function_template.hpp:1064:16: instantiated from ‘boost::function<R(T0)>::function(Functor, typename boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, int>::type) [with Functor = void (*)(const goby::acomms::protobuf::ModemTransmission&, GobyModule*), R = void, T0 = const goby::acomms::protobuf::ModemTransmission&, typename boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, int>::type = int]’ /usr/include/boost/signals/slot.hpp:111:122: instantiated from ‘boost::slot<SlotFunction>::slot(const F&) [with F = void (*)(const goby::acomms::protobuf::ModemTransmission&, GobyModule*), SlotFunction = boost::function<void(const goby::acomms::protobuf::ModemTransmission&)>]’ /usr/local/include/goby/acomms/connect.h:35:11: instantiated from ‘void goby::acomms::connect(Signal*, Slot) [with Signal = boost::signal<void(const goby::acomms::protobuf::ModemTransmission&)>, Slot = void (*)(const goby::acomms::protobuf::ModemTransmission&, GobyModule*)]’ gobyModule.cc:404:66: instantiated from here /usr/include/boost/function/function_template.hpp:112:11: error: too few arguments to function Thank you so much, Matteo

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Serializing handles to opaque objects
by James Amundson 28 Oct '11

28 Oct '11

I am trying to use Boost Serialization with a set of classes which contain handles to opaque objects written in C. (Specifically, the objects are MPI communicator objects and the handles are of the MPI_Comm type, but I don't think that's important for the problem.) Now, I can easily extract the information from the objects necessary to serialize and de-serialize them; that is not the problem. The problem is that several classes have handles to the *same* object. When I restore the objects I need to make certain that all the identical handles end up pointing to the same object. I don't see an easy way to do that. The problem seems to me to be highly analogous to the (solved) problem of serializing pointers, except that the handles are not literally pointers. I'd be grateful for any advice Thanks, Jim Amundson

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[graph] how do i test at compile time if a Graph is directed or undirected?
by Christoph 28 Oct '11

28 Oct '11

Hi, ist it possible to test at compile time if a graph is directed or undirected? I would like the compiler to give an error message if the graph is directed. best regards Christoph

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[boost-users] Cartesian product
by Christoph Heindl 27 Oct '11

27 Oct '11

Hi, I'm on search for an algorithm that produces the cartesian product for n-dimension. The coordinates of each dimension are not limited to numbers. Ideally I'd like to write something along the lines of std::vector<int> d0; // (assume d0 = [0, 3, 2]); std::vector<bool> d1; // (assume d1 = [true]); std::vector<std::string> d2; // (assume d2 = ["hello", "world"]) typedef boost::fusion::vector< std::vector<int>, std::vector<bool>, std::vector<std::string> > tt; tt space(d0, d1, d2); boost::cartesian_product<tt> cp(space); BOOST_FOREACH(const boost::cartesian_product<tt>::value_type &t, cp) { // Invoked for every possible combination of the three dimension. // t is boost::tuple<int, bool, std::string> or similar } I think that something similar can be accomplished using boost.fusion, but I cannot derive the algorithm. What I have found so far is a meta cartesian product [1]. Has anyone such an algorithm lying around? Any help would be greatly appreciated. Best regards, Christoph [1] http://organicvectory.com/index.php?option=com_content&view=article&id=75:b…

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[Tokenizer] Error - Missing Binary operator
by Collin Day 27 Oct '11

27 Oct '11

Hi all, I have been trying to compile some example source code that uses the tokenizer. I am using GCC 4.5.3 with boost 1.47. I get the following compile error: In file included from ../../include/boost/mpl/apply.hpp:23:0, from ../../include/boost/iterator/iterator_facade.hpp:34, from ../../include/boost/iterator/iterator_adaptor.hpp:15, from ../../include/boost/token_iterator.hpp:21, from ../../include/boost/tokenizer.hpp:20, from Path.cpp:4: ../../include/boost/mpl/apply_wrap.hpp:81:31: error: missing binary operator before token "(" ../../include/boost/mpl/apply_wrap.hpp:173:31: error: missing binary operator before token "( I looked on the web, and everything that looks remotley like this said it was a problem with GCC > 4.4, but was fixed in boost 1.37. I have tried with both gcc 4.4.6 and 4.5.3. I don't think I am missing anything since it is just an include file, but I could be wrong. any help would be appreciated. Thanks!

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dijkstra_shortest_paths with a graph with bundled edge properties
by David Doria 27 Oct '11

27 Oct '11

This example works fine: http://programmingexamples.net/index.php?title=CPP/Boost/BGL/DijkstraUndire… However, if I change typedef boost::property<boost::edge_weight_t, float> EdgeWeightProperty; to struct EdgeWeightProperty{float weight;}; (and of course remove the lines adding the weights as properties: boost::add_edge(v1, v2, weight1, g); ) I get crazy template errors: /usr/include/boost/graph/dijkstra_shortest_paths.hpp: In member function ‘void boost::detail::dijkstra_bfs_visitor<UniformCostVisitor, UpdatableQueue, WeightMap, PredecessorMap, DistanceMap, BinaryFunction, BinaryPredicate>::examine_edge(Edge, Graph&) [with Edge = boost::detail::edge_desc_impl<boost::undirected_tag, unsigned int>, Graph = const boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::no_property, EdgeWeightProperty>, UniformCostVisitor = boost::dijkstra_visitor<>, UpdatableQueue = boost::d_ary_heap_indirect<unsigned int, 4u, boost::iterator_property_map<unsigned int*, boost::vec_adj_list_vertex_id_map<boost::no_property, unsigned int>, unsigned int, unsigned int&>, int*, std::less<int>, std::vector<unsigned int> >, WeightMap = boost::adj_list_edge_property_map<boost::undirected_tag, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, unsigned int, const boost::property<boost::edge_bundle_t, EdgeWeightProperty, boost::no_property>, boost::edge_weight_t>, PredecessorMap = unsigned int*, DistanceMap = int*, BinaryFunction = boost::closed_plus<int>, BinaryPredicate = std::less<int>]’: /usr/include/boost/graph/breadth_first_search.hpp:77:47: instantiated from ‘void boost::breadth_first_visit(const IncidenceGraph&, typename boost::graph_traits<IncidenceGraph>::vertex_descriptor, Buffer&, BFSVisitor, ColorMap) [with IncidenceGraph = boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::no_property, EdgeWeightProperty>, Buffer = boost::d_ary_heap_indirect<unsigned int, 4u, boost::iterator_property_map<unsigned int*, boost::vec_adj_list_vertex_id_map<boost::no_property, unsigned int>, unsigned int, unsigned int&>, int*, std::less<int>, std::vector<unsigned int> >, BFSVisitor = boost::detail::dijkstra_bfs_visitor<boost::dijkstra_visitor<>, boost::d_ary_heap_indirect<unsigned int, 4u, boost::iterator_property_map<unsigned int*, boost::vec_adj_list_vertex_id_map<boost::no_property, unsigned int>, unsigned int, unsigned int&>, int*, std::less<int>, std::vector<unsigned int> >, boost::adj_list_edge_property_map<boost::undirected_tag, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, unsigned int, const boost::property<boost::edge_bundle_t, EdgeWeightProperty, boost::no_property>, boost::edge_weight_t>, unsigned int*, int*, boost::closed_plus<int>, std::less<int> >, ColorMap = boost::two_bit_color_map<boost::vec_adj_list_vertex_id_map<boost::no_property, unsigned int> >, typename boost::graph_traits<IncidenceGraph>::vertex_descriptor = unsigned int]’ /usr/include/boost/graph/dijkstra_shortest_paths.hpp:332:5: instantiated from ‘void boost::dijkstra_shortest_paths_no_init(const Graph&, typename boost::graph_traits<Graph>::vertex_descriptor, PredecessorMap, DistanceMap, WeightMap, IndexMap, Compare, Combine, DistZero, DijkstraVisitor, ColorMap) [with Graph = boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::no_property, EdgeWeightProperty>, DijkstraVisitor = boost::dijkstra_visitor<>, PredecessorMap = unsigned int*, DistanceMap = int*, WeightMap = boost::adj_list_edge_property_map<boost::undirected_tag, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, unsigned int, const boost::property<boost::edge_bundle_t, EdgeWeightProperty, boost::no_property>, boost::edge_weight_t>, IndexMap = boost::vec_adj_list_vertex_id_map<boost::no_property, unsigned int>, Compare = std::less<int>, Combine = boost::closed_plus<int>, DistZero = int, ColorMap = boost::two_bit_color_map<boost::vec_adj_list_vertex_id_map<boost::no_property, unsigned int> >, typename boost::graph_traits<Graph>::vertex_descriptor = unsigned int]’ /usr/include/boost/graph/dijkstra_shortest_paths.hpp:383:5: instantiated from ‘void boost::dijkstra_shortest_paths(const VertexListGraph&, typename boost::graph_traits<VertexListGraph>::vertex_descriptor, PredecessorMap, DistanceMap, WeightMap, IndexMap, Compare, Combine, DistInf, DistZero, DijkstraVisitor, ColorMap) [with VertexListGraph = boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::no_property, EdgeWeightProperty>, DijkstraVisitor = boost::dijkstra_visitor<>, PredecessorMap = unsigned int*, DistanceMap = int*, WeightMap = boost::adj_list_edge_property_map<boost::undirected_tag, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, unsigned int, const boost::property<boost::edge_bundle_t, EdgeWeightProperty, boost::no_property>, boost::edge_weight_t>, IndexMap = boost::vec_adj_list_vertex_id_map<boost::no_property, unsigned int>, Compare = std::less<int>, Combine = boost::closed_plus<int>, DistInf = int, DistZero = int, ColorMap = boost::two_bit_color_map<boost::vec_adj_list_vertex_id_map<boost::no_property, unsigned int> >, typename boost::graph_traits<VertexListGraph>::vertex_descriptor = unsigned int]’ /usr/include/boost/graph/dijkstra_shortest_paths.hpp:353:5: instantiated from ‘void boost::dijkstra_shortest_paths(const VertexListGraph&, typename boost::graph_traits<VertexListGraph>::vertex_descriptor, PredecessorMap, DistanceMap, WeightMap, IndexMap, Compare, Combine, DistInf, DistZero, DijkstraVisitor, const boost::bgl_named_params<T, Tag, Base>&, typename boost::enable_if_c<boost::is_base_and_derived<boost::vertex_list_graph_tag, typename boost::graph_traits<VertexListGraph>::traversal_category>::value, boost::graph::detail::no_parameter>::type) [with VertexListGraph = boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::no_property, EdgeWeightProperty>, DijkstraVisitor = boost::dijkstra_visitor<>, PredecessorMap = unsigned int*, DistanceMap = int*, WeightMap = boost::adj_list_edge_property_map<boost::undirected_tag, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, unsigned int, const boost::property<boost::edge_bundle_t, EdgeWeightProperty, boost::no_property>, boost::edge_weight_t>, IndexMap = boost::vec_adj_list_vertex_id_map<boost::no_property, unsigned int>, Compare = std::less<int>, Combine = boost::closed_plus<int>, DistInf = int, DistZero = int, T = int*, Tag = boost::vertex_distance_t, Base = boost::bgl_named_params<unsigned int*, boost::vertex_predecessor_t, boost::no_property>, typename boost::graph_traits<VertexListGraph>::vertex_descriptor = unsigned int, typename boost::enable_if_c<boost::is_base_and_derived<boost::vertex_list_graph_tag, typename boost::graph_traits<VertexListGraph>::traversal_category>::value, boost::graph::detail::no_parameter>::type = boost::graph::detail::no_parameter]’ /usr/include/boost/graph/dijkstra_shortest_paths.hpp:423:7: instantiated from ‘void boost::detail::dijkstra_dispatch2(const VertexListGraph&, typename boost::graph_traits<VertexListGraph>::vertex_descriptor, DistanceMap, WeightMap, IndexMap, const Params&) [with VertexListGraph = boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::no_property, EdgeWeightProperty>, DistanceMap = int*, WeightMap = boost::adj_list_edge_property_map<boost::undirected_tag, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, unsigned int, const boost::property<boost::edge_bundle_t, EdgeWeightProperty, boost::no_property>, boost::edge_weight_t>, IndexMap = boost::vec_adj_list_vertex_id_map<boost::no_property, unsigned int>, Params = boost::bgl_named_params<int*, boost::vertex_distance_t, boost::bgl_named_params<unsigned int*, boost::vertex_predecessor_t, boost::no_property> >, typename boost::graph_traits<VertexListGraph>::vertex_descriptor = unsigned int]’ /usr/include/boost/graph/dijkstra_shortest_paths.hpp:455:7: instantiated from ‘void boost::detail::dijkstra_dispatch1(const VertexListGraph&, typename boost::graph_traits<VertexListGraph>::vertex_descriptor, DistanceMap, WeightMap, IndexMap, const Params&) [with VertexListGraph = boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::no_property, EdgeWeightProperty>, DistanceMap = int*, WeightMap = boost::adj_list_edge_property_map<boost::undirected_tag, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, unsigned int, const boost::property<boost::edge_bundle_t, EdgeWeightProperty, boost::no_property>, boost::edge_weight_t>, IndexMap = boost::vec_adj_list_vertex_id_map<boost::no_property, unsigned int>, Params = boost::bgl_named_params<int*, boost::vertex_distance_t, boost::bgl_named_params<unsigned int*, boost::vertex_predecessor_t, boost::no_property> >, typename boost::graph_traits<VertexListGraph>::vertex_descriptor = unsigned int]’ /usr/include/boost/graph/dijkstra_shortest_paths.hpp:473:5: instantiated from ‘void boost::dijkstra_shortest_paths(const VertexListGraph&, typename boost::graph_traits<IncidenceGraph>::vertex_descriptor, const boost::bgl_named_params<P, T, R>&) [with VertexListGraph = boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::no_property, EdgeWeightProperty>, Param = int*, Tag = boost::vertex_distance_t, Rest = boost::bgl_named_params<unsigned int*, boost::vertex_predecessor_t, boost::no_property>, typename boost::graph_traits<IncidenceGraph>::vertex_descriptor = unsigned int]’ Any chance anyone can interpret these? Thanks, David

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