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About property maps and the Boost Graph module
by Ken Yasumoto-Nicolson 26 Oct '04

26 Oct '04

Hi folks, I've searched the archives and boost.org trying to find some help, but I still can't get my head around how the property maps are supposed to work. I'm pretty new to Boost, so I'm maybe not too familiar with the underlying concepts, etc, so forgive me if my question seems a little too basic! My problem is this: Given a directed graph with a single start and end point, I want for each node (vertex) to build a list of all the other nodes that can be reached from the current node. The algorithm is simple, I think: do a depth_first_search() and implement my code on dfs_visitor::finish_vector(). This skeleton I have done. However, the bit I can't get my head around is how to use property maps to collect the info. The key parts of my best effort so far are: struct statement_list_t { typedef boost::vertex_property_tag kind; }; typedef boost::property< statement_list_t, std::set<size_t> > StatementListProperty; typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::bidirectionalS, StatementListProperty, boost::no_property > ADJ_GRAPH; struct connection_detector : public boost::dfs_visitor<> { public: connection_detector() {} template <class Vertex, class Graph> void finish_vertex(Vertex u, const Graph& g) { /* for each child in out_edges( u, g ) current node set = union_of( current, child ) */ } } However, my questions are: 1. std::set<size_t> - is the size_t the best type to store a reference to a vector in? 2. In finish_vertex<> (or other places) how do I address the StatementListProperty value for a given vertex? 3. How would I use an Exterior Property Map instead? Thanks for any advice! Ken

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shared_ptr and shared_from_this
by Timothy Ritchey 26 Oct '04

26 Oct '04

I have an interpreter that uses a visitor pattern while performing a reduction of the program tree. As part of the visitor pattern, each class that can be a node in the tree must respond to: virtual void accept(Visitor& v); where each node then implements by calling visitor with itself using the proper type. The function calls in visitor are like: void visit(shared_ptr<Node> node); void visit(shared_ptr<Type> node); etc. (where Type is a descendant of node BTW). Normally with the visitor pattern (GOF style in this case), the implementation of accept is simply: void Node::accept(Visitor &v) { v.visit(this); } I've tried adding enable_shared_from_this<...> as a superclass of my nodes, and returning shared_from_this(), which works in some cases, but in others just seems to hang. These occur in classes that are a little more complex. For example, I have a TypeTemplate<T> class that wraps to underlying types TypeTemplate<int>, TypeTemplate<float>, TypeTemplate<etc>. I've tried adding enable_shared_from_this<TypeTemplate<T> >, and then having an implmentation void TypeTemplate<T>::accept(Visitor &v) { v.visit(enable_shared_from_this<TypeTemplate<T> >::shared_from_this()); } but it just hangs on both vc7.1 on windows and Xcode on OS X. (I had to add the extra scoping because I got complaints that "shared_from_this() was ambiguous in multiple inheritance.") I read in some past postings that the shared_from_this template doesn't work so well for complex class hierarchies, and I am wondering if I am running into that. I was thinking of putting my own internal_weak_ptr into the classes, but was confused by some of the examples I have seen. Most of them seem to reference a static function create() which instantiates the weak_ptr, and returns a shared_ptr<X>. When I consider my situation: shared_ptr<Node> aNode(new Node(...)); Visitor v; aNode->accept(v); How does the accept implementation return a shared_ptr that is linked with aNode? I've looked through the enable_shared_from_this implementation, and can't figure out how it is supposed to work. even if I return shared_from_this(), I'm not sure now that is linked to aNode. Does everything have to go through a factory like create()? Sorry for the long rambling e-mail. I hope it makes sense what I am trying to do. Cheers, tim

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"nested" spirit grammars and semantic actions
by Tim Robertson 26 Oct '04

26 Oct '04

Hi, I'm looking for advice on ways to "nest" spirit grammars that use semantic actions. In the past, I have written a spirit grammar that parses 2-dimensional array data from a file, and puts the data into an array object of my choosing. To do this, the grammar defines a new functor (array_insert) and calls the functor whenever a new array element is parsed. The functor puts the element into a reference to the destination object, held within the grammar: struct array_grammar { array_grammar(MyMatrix & m) : _inserter(m) {} struct array_inserter { array_inserter(MyMatrix & m) : _m(m) {} // operator() defined here... MyMatrix & _m; } // ...the usual grammar components... array_inserter _inserter; }; This works, as expected. However, I now have to write a parser for a file containing a collection of 2D arrays, where each array is delimited by tags (say, "BEGIN" and "END"). I would like to push each array into a std::vector of MyMatrix objects. Thus, it would be nice if I could re-use the array_grammar, and write a grammar which uses it to parse each array in the larger file: struct multi_array_grammar { multi_array_grammar(std::vector<MyMatrix> & v) : _inserter(v) {} struct array_inserter { array_inserter(std::vector<MyMatrix> & v) : _v(v) {} // ... operator(), etc. std::vector<MyMatrix> & _v; }; template <typename ScannerT> struct definition { definition(multi_array_grammar const & self) { array_begin = str_p("BEGIN"); array_end = str_p("END"); // Problem: how to create array_grammar with correct reference? array_grammar array(???); r = array_begin >> +array >> array_end; } }; array_inserter _inserter; }; The problem is that I can't figure out how to instantiate an array_grammar (which requires a reference to the current MyMatrix object) in order to parse the individual arrays. I have solved this problem by creating a functor in multi_array_grammar which calls the parse function for array_grammar directly, but this seems ugly to me. Do any of you have a better way? -Tim

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[FSM] Saving/Restoring the state_machine
by spooky＠go.ro 25 Oct '04

25 Oct '04

Is it possible to save the current state of the state machine to a stream or by means of boost::serialize? Details: I am building a state machine using boost::fsm that is trying to follow the activity of items in a processing pipeline. I am trying to implement a procedure that allows the software to be turned off and on again without loosing the information about the current state. Naturally, I want to have a timer and, at some interval I checkpoint the state machine and save the binary representation to a file. The contents of the file are used during application startup to restore the state machine. Can I achieve this functionality with boost::fsm? Best regards, Emil Mieilica

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tcp/ip software
by Greg Silverman 25 Oct '04

25 Oct '04

Since Boost does not have a library for TCP/IP, I was wondering what OO interface to sockets is most popular with Boost users? Greg Silverman Northrop Grumman Sunnyvale, CA

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Boost under QNX 6.2.1
by Ghorashi, Ali 25 Oct '04

25 Oct '04

Dave, I'm also trying to compile boost_1_31_0 under qnx. Could you post the QNX libraries you mentioned? Ali Ghorashi (719) 277-5506 Hardware Engineering Lockheed Martin Mission Systems 9970 Federal Dr M/S 01P, Colorado Springs CO, 80920

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RE: [Boost-users] About properties
by Townsend, Matthew 25 Oct '04

25 Oct '04

>... > >I guess the functionality he wants is like the property keyword in VC++. >Unfortunately this is a Microsoft only extension. This is acutally stolen by Microsoft from Borland Delphi's Object Pascal. I really liked the feature and wished C++ had a solution. I haven't spent any time thinking about adding it, or how to. >Any ideas? Suggestions? > >Thanks > >-delfin -matt _______________________________________________ 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] Re: Bjam and cygwin
by Foster, Gareth 25 Oct '04

25 Oct '04

Hmm, could well be, I just downloaded a binary of bjam rather than building it, so I bet the default download is a windows build. I did get the install to work like this, however, my project doesn't find the boost includes, even though I installed to /usr/local, shouldn't they be picked up there? What autotools magic do I need if that isn't the case? Thanks Gaz -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of David Abrahams Sent: 24 October 2004 07:00 To: boost-users(a)lists.boost.org Subject: [Boost-users] Re: Bjam and cygwin "Foster, Gareth" <gareth.foster(a)siemens.com> writes: > Just for other peoples information (these mails show up in an searchable > online archive somewhere afterall afaik), I fixed this problem by setting > the path 'in a windows' way, rather than a unix way, even though I was > building from the cygwin shell. That means ... > > bjam "-sTOOLS=GCC" "--target=/usr/local" install > > Becomes ... > > bjam "-sTOOLS=GCC" "--target=c:\cygwin\usr\local" install > > That's from memory, so excuse any slight inacuracies in the syntax there. It > does get rid of the <directory-guist> weirdness. > > Hope this helps somebody somewhere. > > Regards That's surely because you're using a bjam that was built for windows, not for Cygwin. If you rebuild bjam under Cygwin I think you'll see that Cygwin paths work. -- Dave Abrahams Boost Consulting http://www.boost-consulting.com _______________________________________________ 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] Bjam and cygwin
by Foster, Gareth 24 Oct '04

24 Oct '04

Just for other peoples information (these mails show up in an searchable online archive somewhere afterall afaik), I fixed this problem by setting the path 'in a windows' way, rather than a unix way, even though I was building from the cygwin shell. That means ... bjam "-sTOOLS=GCC" "--target=/usr/local" install Becomes ... bjam "-sTOOLS=GCC" "--target=c:\cygwin\usr\local" install That's from memory, so excuse any slight inacuracies in the syntax there. It does get rid of the <directory-guist> weirdness. Hope this helps somebody somewhere. Regards Gaz -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Foster, Gareth Sent: 18 October 2004 11:37 To: 'boost-users(a)lists.boost.org' Subject: [Boost-users] Bjam and cygwin Hello all, I keep getting the following errors using bjam ... "<directory-grist>" I have set the install to use GCC and install to /usr. I also tried with /usr/local. I read that it might be a windows/unix line break thing, but I tried the zip file, bz2 and normal tarball, extracting with the windows gui tools and the cygwin cli tools. What am I doing wrong? Thanks for any help. Gaz -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Joel Sent: 15 October 2004 00:55 To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] Spirit Foster, Gareth wrote: > Hello all, > > I am trying to find some source code that uses spirit to parse C++ and > convert it to HTML, i found some on google, but i misplaced it and i > can't find it again. It looked like it could have been an example > provided with the library, but i can't see it listed in the documentation. > > On a side note, anyone know the best way to use boost with cygwin? From > source? Is there even another way? See the repository: http://spirit.sourceforge.net/repository/applications/show_contents.php Cheers, -- Joel de Guzman http://www.boost-consulting.com http://spirit.sf.net _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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help with boost thread compile
by Sara Collins 23 Oct '04

23 Oct '04

This might be very easy for a lot of you but I've been banging my head on the wall. I just installed the boost library and tried to run a simple test file using boost.thread.mutex #include <boost/thread/mutex.hpp> int main() { boost::mutex m; } I got this compilation error message: undefined reference to `boost::mutex::mutex[in-charge]()' I guess I have to link in the libboost_thread.dll file somehow but I don't seem to find a solution how. Perharps I've been searching the wrong places. Please help the newbie. Thanks a lot in advance. _______________________________ Do you Yahoo!? Declare Yourself - Register online to vote today! http://vote.yahoo.com

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