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Boost.Coroutine + objects
by Van Pers 01 Oct '13

01 Oct '13

Hello guys, I am using Boost Coroutines but I would like to use them in a Objected-Oriented way. So, I tried to rewrite parallel.cpp (boost/libs/coroutine/example) using the example functions like class methods, but it did not work. This is my code, anybody can help me? My code: typedef boost::coroutines::coroutine< void() > coroutine_t; class Abc{ public: void first( coroutine_t::caller_type & self) { std::cout << "started first! "; for ( int i = 0; i < 10; ++i) { self(); std::cout << "a" << i; } } void second( coroutine_t::caller_type & self) { std::cout << "started second! "; for ( int i = 0; i < 10; ++i) { self(); std::cout << "b" << i; } } void third(){ coroutine_t c1( boost::bind( first, _1) ); coroutine_t c2( boost::bind( second, _1) ); while ( c1 && c2) { c1(); std::cout << " "; c2(); std::cout << " "; } } }; int main( int argc, char * argv[]) { Abc* myabc = new Abc(); myabc->third(); std::cout << "\nDone" << std::endl; return EXIT_SUCCESS; } Thank you, Van

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returning range adaptor generator
by Nick Stokes 01 Oct '13

01 Oct '13

What should be the return type for a function that returns an adapted range? E.g. template<class Range> xxx getIndirected( const Range& r ) { return r | boost::adaptors::indirected; } The use case being, providing a API with these little useful helpers without forcing the user to know about Boost.Range at all. Like so: #include <myapi.hpp> #include <boost/foreach.hpp> LegacyPointerContainers f; // contains Foo pointers BOOST_FOREACH( Foo& f, TraverseFoo( f ) ) { } /// where in myapi.hpp xxx TraverseFoo( LegacyPointerContainers& f ) { return getIndirected( makeRange(f) ) ; } PS: This is all C++03. No autos. Thanks Nick

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BGL: write_graphviz_dp taking in count values of dynamic_properties
by Pablo Madoery 30 Sep '13

30 Sep '13

Hi, I have the following code that print a graph taking in count values of dynamic_properties: #include<iostream> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/graphviz.hpp> using namespace std; using namespace boost; struct VertexInfo { int id; }; struct EdgeInfo { double weight; bool enable; }; typedef adjacency_list<listS, vecS, bidirectionalS, VertexInfo, EdgeInfo> Graph; int main() { //////////////////////////////////////////////////////////////////////////////////////////// Graph graph; Graph::vertex_descriptor a = add_vertex(graph); Graph::vertex_descriptor b = add_vertex(graph); Graph::vertex_descriptor c = add_vertex(graph); Graph::vertex_descriptor d = add_vertex(graph); Graph::edge_descriptor e1 = (add_edge(a, b, graph)).first; Graph::edge_descriptor e2 = (add_edge(a, b, graph)).first; Graph::edge_descriptor e3 = (add_edge(b, c, graph)).first; Graph::edge_descriptor e4 = (add_edge(c, a, graph)).first; Graph::edge_descriptor e5 = (add_edge(c, a, graph)).first; Graph::edge_descriptor e6 = (add_edge(c, d, graph)).first; graph[e1].weight = 5; graph[e2].weight = 10; graph[e3].weight = 6; graph[e4].weight = 14; graph[e5].weight = 2; graph[e6].weight = 3; graph[e1].enable = true; graph[e2].enable = false; graph[e3].enable = true; graph[e4].enable = false; graph[e5].enable = true; graph[e6].enable = false; ofstream ofs("graph.dot"); dynamic_properties dp; dp.property("node_id", get(vertex_index, graph)); dp.property("label", get(&EdgeInfo::weight, graph)); dp.property("taillabel", get(&EdgeInfo::enable, graph)); write_graphviz_dp(ofs, graph, dp); cout << "fin" << endl; return 0; } /////////////////////////////////////////////////////////////////////////////////// there is a property called "enable" in the edges that I print in the tails of the arrows. But what i really want is that when enable = false the style of the arrow be different ("invis" for example). How can i do that? Thanks!

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Tree traversal in boost spirit
by Olivier Austina 30 Sep '13

30 Sep '13

Hi, I would like to traverse a parsed tree. The parsing is fine. I am using this tutorial : http://en.highscore.de/cpp/boost/parser.html This is the instruction used for parsing : boost::spirit::parse_info<> pi = boost::spirit::parse(data.c_str(), g, boost::spirit::space_p); I would like to traverse the parsed tree like classical tree (Pre-order, In-order, Post-order) to have data in a given order. Any suggestion will be appreciated. Thank you. Regards Olivier

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[Graph] Stable topological_sort? And topological_sort woes in general.
by Dominique Devienne 30 Sep '13

30 Sep '13

I'm sorting a set of SQL tables with foreign-key constraints. I'm currently using BGL's topological_sort for that, but struggled quite a bit because: * I didn't manage to adapt my own data-structure, so ended-up sorting indices to an array of my entries, and generated the edges as indice pairs on in this array (like the doc example). * Discovered via unit testing topological_sort didn't like vertices with no associated edges (a "free standing" table, with no relationships), so I'm "manually" removing those. * Discovered via unit testing topological_sort didn't like "duplicate" edges (a table with several columns referencing the same parent table), so I'm also manually removing those too. I confess to not trying to fully understand the BGL, nor to have read the book. Given what I was trying to do, as outlined above, was using topological_sort really the best tool for the job? What are the alternatives, if any? For my own education, why "singleton" vertices and duplicate edges make topological_sort break? But what brings me here today is to ask about a "stable" topo-sort. When I have several vertices which are all "unrelated" and thus sort at the same "level", topological_sort does not preserve the relative order of those "sibling" vertices, and I'd like something fully deterministic that I can count on. What are my options? Does BGL provide something like this? As a concrete example, given tables A, B, C, with A depending on both B, C, topological_sort gives me the C, B, A order (or adding the "levels" (C, B), A), while I'd like B, C, A, i.e. preserving the relative order of B, C. Thanks for any insight. --DD PS: What about getting a topo-sort, but which also gives you the "levels", so that you can schedule those independent tasks (on each level) in parallel for example? Does BGL provide something like this? I've done it in the past with the help of the Sedgewick book, but I see a single topo-sort in BGL.

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[Serialization] How do I make boost::serialization work with std::shared_ptr?
by Arman Schwarz 30 Sep '13

30 Sep '13

Hi everyone, this is my first post so I apologies if I got some of the housekeeping wrong. I did my best. I also realise that this is likely to be a common question but all the responses I could find on Stackoverflow (among others) were related to older implementations of boost. My understanding is that Boost 1.54 is supposed to support `std::shared_ptr`. To illustrate the issue I am having, suppose we want to serialize a class containing a vector of shared pointers, along with a static `load` function that will build the class from a file and a `save` function that will store the instance to a file, and suppose that we can't just use the `serialize` member function for whatever reason (this particular example doesn't really illustrate such a case but in my code I can't use the `serialize` member function so this example doesn't use it either): #include <boost/archive/text_iarchive.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/serialization/vector.hpp> #include <boost/serialization/shared_ptr.hpp> #include <fstream> #include <memory> #include <vector> class A { public: std::vector<std::shared_ptr<int>> v; void A::Save(char * const filename); static A * const Load(char * const filename); ////////////////////////////////// // Boost Serialization: // private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int file_version) {} }; // save the world to a file: void A::Save(char * const filename) { // create and open a character archive for output std::ofstream ofs(filename); // save data to archive { boost::archive::text_oarchive oa(ofs); // write the pointer to file oa << this; } } // load world from file A * const A::Load(char * const filename) { A * a; // create and open an archive for input std::ifstream ifs(filename); boost::archive::text_iarchive ia(ifs); // read class pointer from archive ia >> a; return a; } namespace boost { namespace serialization { template<class Archive> inline void save_construct_data( Archive & ar, A const * t, unsigned const int file_version ) { ar << t->v; } template<class Archive> inline void load_construct_data( Archive & ar, A * t, const unsigned int file_version ) { ar >> t->v; } } } int main() { } Why doesn't this code compile? What am I doing wrong here? The error message states that 'serialize' is not a member of 'shared_ptr'. Why am I am getting this message?

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Re: [Boost-users] Running Regular expression (RE) over a list, array or map
by Olivier Austina 28 Sep '13

28 Sep '13

Hi, I try to use pattern matching approach for a dataset with multilevel tags. Suppose we have 2 sets of features: F and H with the following tags F={f0, f1, f2, f3} and H={h0, h1, h2, h3, h4} to describe a set of elements E={e1, e2, e3.....en}. We have in a table a sequence of E elements describe as following: E e1 e2 e3 e4 e5 e6 e7 e8 ...........en F *f3 f0 f0 f0* f2 *f3 f0 * f2 f0 H h4 h0 h4 *h1* h0 h2 *h3* h2 h1 The order in which e1, e2 e3...... appear is important as words in a sentence. Suppose we have the following RE with f3 and f0 as following: f3f0+ . It will match the corresponding sequence e1, e2, e3, e4 and e6, e7 in E. Now we want to add additional constraint as the last f0 should map a h1 in H. In this case the final result will be only the sequence e1, e2, e3, e4 because in the last sequence e6, e7 the f0 map h3 in H.The final result is always E sequences but the RE and constraint can be based on E, F or H. May be it becomes a bit clear. Thank for your help. Regards Olivier 2013/9/27 Anthony Foiani <tkil(a)scrye.com> > Olivier, greetings -- > > Olivier Austina <olivier.austina(a)gmail.com> writes: > > > I am wondering if it is possible to run directly regular expression > > over a list and getting the indexes (begging and end) of the > > match. For example, I have a list of strings and a regular > > expression and I want to know which part of the list matches the RE > > and get the corresponding indexes in the list. > > It looks like you got some other suggestions, but if they're not what > you're looking for, you might want to clarify your request. > > In particular, it's not clear to me whether you want to match the RE > against each individual item (which can be parallelized, but the > result is a membership bitmap or subset, not a range), or if you want > to match the RE against the concatenated value, or the largest span of > continuous values (which are the requests that make the most sense if > you want a starting and ending index). > > Some sample code would probably clarify things. > > E.g., given: > > typedef std::vector< std::string > string_vec; > const string_vec sv{ "foo", "bar", "baz" }; > > And you wanted to match: > > const boost::regex re{ "ba.*" }; > > What answer do you want to see? > > * The membership bitmap would be something like: [ 0, 1, 1 ] > > * The subset would be: { "bar", "baz" } > (This is basically a "grep" operator.) > > * The "range" answer would be sv.begin()+1, sv.begin()+3 (since > "barbaz" matches). > > * The other "range" answer would be the same, but because "bar" > matches, and "baz" matches, so the range represents the (longest?) > set of elements that individually match the given regex. This > ends up being something of a meta-regex, or if you prefer, the > result of searching the concatenated string for instances of > "(?:re)+". > > Or is there some other interpretation that you're trying to get at? > > Happy hacking, > Tony > > p.s. Heh. Guess who just finished a few interviews where "spot the > under-specified problem" was important... > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users >

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Re: [Boost-users] [geometry] within(Poly, Poly)
by Barend Gehrels 27 Sep '13

27 Sep '13

> Barend Gehrels wrote: >> On 26-9-2013 23:01, Adam Wulkiewicz wrote: >>> Barend Gehrels wrote: >>> >>>> >>>>> >>>>> So must I handle each special case, analysing the exterior rings, polygons inside holes, holes inside holes, etc? Or do you see some other, clever way of doing it? >>>> >>>> Yes, all turn information should be totally independent on segments being exterior or interior (iff the orientation is correct w.r.t. the compile-time specified orientation) >>> >>> Ok so the algorithm complicates, correct me if I'm wrong: >>> >>> If P1 exterior isn't inside P2 exterior >>> return NOT_WITHIN >>> If P2 has holes >>> If P1 exterior is disjoint or only touches holes of P2 >>> return WITHIN >>> If holes of P2 which intersects P1 are also inside P1 holes >>> return WITHIN >>> else >>> return NOT_WITHIN >> >> You are right - if there are holes, this must be checked. See also the unit-tests for union.cpp (with TEST_WITH_SVG): union_wrapped, union_winded, union_within_holes_disjoint, union_intersect_holes_disjoint, ... >> >> For touches this is done in "rings_containing", this is probably possible here too. That makes it not really complex and because turns are OK for all exterior/interior combinations, the holes are not a big issue. >> >> For union/intersection, and also for dissolve in intersections, this is done in "select_rings" (the dissolve.hpp contains a simple version that might do ; the others are in overlay.hpp) They are followed by "assign_parents" but that is probably not necessary for this algorithm. >> >> >> >>> >>> And holes should be reversed before checking because they have different orientation than the exterior ring. >> >> No, we assume correct polygons. And all turn info is correct for holes. We don't have to check (besides for things located inside each other without intersections). >> I don't know if you mean this, but for information: we have a specific type for polygons where order is dynamic (both allowed: order_undetermined) but that is not yet implemented anywhere. >> > > Ok now I'm checking special cases and I think that my previous assumtions wasn't fully ok. Correct me if I'm wrong. > > Of course method 'i' and operation 'xx' is automatic fail. ? xx fails but i is ok for turns including on holes? > > Only if we have operation 'u' we must worry about > 'uu' - touches from the outside > 'ux' - is outside > 'ui' - the curve potentially goes to the other side of the second curve. ? yes but this all means failure for all turns including holes? (except ui, sometimes) > > All other combination with operations 'i' and 'c|c' are ok, also t+cc, m+cc? > > So additionally we should check if points of segments for which u|i was generated are inside the polygon. This would be ok for '[not] within *.svg', '(2-5).svg' but would fail for '1.svg'. However in those cases there would be uu there so it might be used as well. So I guess if there are some 'u|i' operations we should check if all (or some) points are inside. If there is some 'u|u' we should check if on the same point there are no other intersections to detect cases like 'ok_uu.svg'. > > Of course if there are no intersections, only one point may be tested if it's inside. > > What do you think? > sorry I don't understand it. As I said before, holes are processed correctly automatically for any turn. You don't have to process any turn special for any hole. So i is intersection, this is Ok. But u is union, then the within should fail. The interior is really the inside of a polygon, not the hole. That is outside.... Or maybe I did not understand your mail. I never handle holes separately in any turn in the whole traverse process. As long as the direction is ccw (for a cw polygon), it all goes ok. The interior is always on the right side. Of course, as we discussed before, if a hole does not have any turnpoints, we should check it separately and differently, not with turn info Regards, Barend Sent from iPad. Barend Gehrels www.barendgehrels

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[Container] Using container of BOOST_MOVABLE_BUT_NOT_COPYABLE type with std algorithm
by kwanti 27 Sep '13

27 Sep '13

I try to use std::remove_if with boost.container of BOOST_MOVABLE_BUT_NOT_COPYABLE type in c++98 compiler. The compilation failed because std::remove_if in c++98 is not implemented with boost.move emulation. Is there any implementation of remove_if in boost that is implemented with boost.move? I found one remove_if algorithm in boost.range library but I can't find in the documentation whether it is using boost.move emulation. -- View this message in context: http://boost.2283326.n4.nabble.com/Container-Using-container-of-BOOST-MOVAB… Sent from the Boost - Users mailing list archive at Nabble.com.

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Running Regular expression (RE) over a list, array or map
by Olivier Austina 26 Sep '13

26 Sep '13

Hi, I am wondering if it is possible to run directly regular expression over a list and getting the indexes (begging and end) of the match. For example, I have a list of strings and a regular expression and I want to know which part of the list matches the RE and get the corresponding indexes in the list. Any suggestion is welcome. Thank you. Regards Olivier

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