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[Boost Serialization] Cannot handle UTF-8 BOM bytes in XML file
by Tijmen van Voorthuijsen 13 Apr '11

13 Apr '11

Hi, I am using boost::archive::xml_woarchive to create XML files under Windows, Visual Studio 2008, and in wide character mode. The boost::archive::xml_woarchive does not write the UTF-8 three BOM bytes to the file and from http://en.wikipedia.org/wiki/Byte_order_mark I understand that this is all right since it is optional and even not recommended. Problems start when I want to edit the file in for example XML Notepad which adds the three BOM bytes when saving. Under Windows this seems normal behavior. Then parsing the XML file throws an exception through the boost::archive::xml_wiarchive. My question/recommendation: - Why can't the boost::archive::xml_serialization library not cope with the UTF-8 BOM bytes? - I would recommend that the library can handle XML UTF-8 files, with and without the three BOM bytes. Both are in fact valid UTF-8 XML files. I now check for the BOM bytes myself before I parse the ifstream in boost::xml_serialization and that works fine. Many thanks for your answer. Tijmen van Voorthuijsen

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Re: [Boost-users] Cycle detection in a directed graph with adjacency_matrix
by Jeremiah Willcock 13 Apr '11

13 Apr '11

On Tue, 12 Apr 2011, albert kao wrote: > After adding "boost::" before "graph_traits", the compile errors are: > adjacency_matrix_is_cyclic.cpp:9: error: expected class-name before ‘{’ token > adjacency_matrix_is_cyclic.cpp: In function ‘bool has_cycle(const Graph&)’: > adjacency_matrix_is_cyclic.cpp:26: error: ‘generic_dfs_v1’ was not declared in this scope > > adjacency_matrix_is_cyclic.cpp: > #include <iostream> > #include <boost/graph/graph_utility.hpp> > #include <boost/graph/adjacency_matrix.hpp> > > typedef boost::adjacency_matrix<boost::directedS> Graph; > typedef boost::graph_traits<Graph>::edge_descriptor edge_t; > > struct cycle_detector : public dfs_visitor_default > { > cycle_detector(bool & cycle): has_cycle(cycle) > { > } > void > back_edge(edge_t, const Graph &) > { > has_cycle = true; > } > bool & has_cycle; > }; > > bool > has_cycle(const Graph & g) > { > bool has_cycle = false; > cycle_detector vis(has_cycle); > generic_dfs_v1(g, vis); > return has_cycle; > } > > enum { A, B, C, D, E, F, N }; > const char* name = "ABCDEF"; > > int main(int argc, char *argv[]) > { > Graph g(N); > add_edge(B, C, g); > add_edge(B, F, g); > add_edge(C, A, g); > add_edge(C, C, g); > add_edge(D, E, g); > add_edge(E, D, g); > add_edge(F, A, g); > > std::cout << "vertex set: "; > boost::print_vertices(g, name); > std::cout << std::endl; > > std::cout << "edge set: "; > boost::print_edges(g, name); > std::cout << std::endl; > > std::cout << "out-edges: " << std::endl; > boost::print_graph(g, name); > std::cout << std::endl; > > std::cout << "has_cycle(g) " << has_cycle(g) << std::endl; > > return 0; > } You also need boost:: before dfs_visitor_default. You should also use boost::depth_first_search instead of generic_dfs_v1 (which is internal). -- Jeremiah Willcock

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Cycle detection in a directed graph with adjacency_matrix
by albert kao 13 Apr '11

13 Apr '11

Is it possible to detect any cycle in a directed graph with the adjacency_matrix of the Boost Graph Library? My test program has this compile errors: adjacency_matrix_is_cyclic.cpp:6: error: expected initializer before ‘<’ token adjacency_matrix_is_cyclic.cpp:9: error: expected class-name before ‘{’ token adjacency_matrix_is_cyclic.cpp:14: error: ‘edge_t’ has not been declared adjacency_matrix_is_cyclic.cpp: In function ‘bool has_cycle(const Graph&)’: adjacency_matrix_is_cyclic.cpp:26: error: ‘generic_dfs_v1’ was not declared in this scope $ cat adjacency_matrix_is_cyclic.cpp #include <iostream> #include <boost/graph/graph_utility.hpp> #include <boost/graph/adjacency_matrix.hpp> typedef boost::adjacency_matrix<boost::directedS> Graph; typedef graph_traits<Graph>::edge_descriptor edge_t; struct cycle_detector : public dfs_visitor_default { cycle_detector(bool & cycle): has_cycle(cycle) { } void back_edge(edge_t, const Graph &) { has_cycle = true; } bool & has_cycle; }; bool has_cycle(const Graph & g) { bool has_cycle = false; cycle_detector vis(has_cycle); generic_dfs_v1(g, vis); return has_cycle; } enum { A, B, C, D, E, F, N }; const char* name = "ABCDEF"; int main(int argc, char *argv[]) { Graph g(N); add_edge(B, C, g); add_edge(B, F, g); add_edge(C, A, g); add_edge(C, C, g); add_edge(D, E, g); add_edge(E, D, g); add_edge(F, A, g); std::cout << "vertex set: "; boost::print_vertices(g, name); std::cout << std::endl; std::cout << "edge set: "; boost::print_edges(g, name); std::cout << std::endl; std::cout << "out-edges: " << std::endl; boost::print_graph(g, name); std::cout << std::endl; std::cout << "has_cycle(g) " << has_cycle(g) << std::endl; return 0; }

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[Fusion] Adapting read-only fields of ADTs
by Sebastian Redl 12 Apr '11

12 Apr '11

Hi, How would I use BOOST_FUSION_ADAPT_ADT to turn an ADT that doesn't expose setters into a read-only sequence? In other words, what do I pass as set_exprN if there is no valid set expression? Sebastian

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a quick question regarding boost::bind, with a test case
by Littlefield, Tyler 12 Apr '11

12 Apr '11

Hello all: I have a quick question regarding boost::bind, as the subject line says. This isn't a very viable example, but it works well enough to show what I want. I have a callback I am using boost::bind to bind to, and I am passing a function object in as shown by the following code: #include <cstdio> #include <boost/bind.hpp> #include <boost/function.hpp> class Math { public: void Add(int a, int b, int c, boost::function<void (int)> printer); { printer(a+b+c); } }; void Printer(int p) { printf("%d\n", p); }How might I make this work? I am not sure how I can pass that as the fourth argument so that the function can be called like (1,2,3) etc. Also, in the actual problem I moved the function object to the first argument, (which just ment changing the prototype and actual function), but I still got errors. -- Thanks, Ty

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[function] How to get boost::function parameters, return type.
by Mostafa 12 Apr '11

12 Apr '11

Hi, Is it possible to decompose boost::function into it's "constituent" parameters and return type, a la Boost.FunctionTypes? Thanks, Mostafa

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[boost-user][asio] is packet analysis feasible, and if so how to proceed (references for learning about it needed)
by Ted Byers 12 Apr '11

12 Apr '11

I am investigating the possibility of developing something like a web-shield using boost::asio. What I mean is this. One vulnerability for ecommerce sites is that a session may be hijacked once a user has been validated. Someone intent on fraud may then use that session for a variety of different kinds of fraud. I expect that the lowest level IP address has to be the actual machine making each request (otherwise the attacker would not be able to get the responses to requests he's made), and that one of the things a fraudster may be doing is falsifying the IP addresses in HTTP headers. I also expect some may be using proxy servers to hide their real identity or location. The first thing I need to learn about is whether there are classes or structs defined within asio that facilitate getting packets in a form that would support the sort of packet analysis that may be useful. I would suppose I would need to make a set of classes that collects HTTP headers, to ease examining them particularly for IP data. Ideally, I'd like to be able to examine each major OSI layer (in part, just to learn how they work in real life). And I' like to try to examine the route by which a given HTTP request as arrived at the server that is to handle it, if that is at all possible. And, I'd like to investigate what sorts of patterns ought to be considered with a view toward detecting any form of misbehaviour a fraudster may resort to. If any of this proves feasible, I'd like to create an intelligent 'shield' based on asio that receives incoming http traffic, examines it for misconduct, and if no such behaviour is found just forward the request on to the real server, and if there is evidence of misbehaviour, redirect the user to either static advertizing pages or whatever challenge-response system a merchant may want to try to use in order to reduce his vulnerability to online fraud. I have yet to see any ecommerce software that tries to protect both consumers and merchants from online fraud in this manner, and have spent much of my time writing code that tries to detect fraud, among other problems, after the fact. But it is such a costly process for some merchants, I would like to become more pro-active, to try to prevent it. Alas, although I have written plenty of quantitative code, I have no experience with network programming in C++, so I don't really know what is feasible (but being an R&D kind of guy, I have no qualms about trying to learn stuff that is new to me ;-) Any insights into what is available and what is possible (with URLs to useful resources) would be greatly appreciated. Thanks Ted

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[Boost.MPI] Scattering/Sending a complicated object
by Ryan Lewis 12 Apr '11

12 Apr '11

I have an object which has as a private type a boost::unordered_map<Object,Struct>, and an iterator, which iterates over the map elements. For a given <Object, Struct> map element, the value Struct has a member variable, which is an integer storing a value between 0,...,#NUM_PROCESSORS-1. I'd like to 'scatter' the object by creating new instances of this object on all the threads, where a given <key,value> pair is on processor i, if value has this integer set to be value i. I suppose I could perform a large number of Sends and Receives, i.e. iterate over the complex, and then send a <key,value> pair to the correct worker node every time I find it, but, this seems bad communication wise? Would there be a way to somehow buffer the sends happen at once? Or is there possibly an even better way of doing this? -rhl

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[Serialization] How to serialize a derived type but deserialize it as a base type pointer?
by Jerry 12 Apr '11

12 Apr '11

I know that we can serialize/deserialize a derived type through a base type pointer (using register_type()). But I cannot serialize a derived type and deserialize it through a base type pointer. It seems to me the data type in serialization and deserialization should be extactly the same one. What I want is, Base{...}; Derived : Base{...}; Derived d; boost::archive::binary_oarchive oa(...); oa << d; // serialize a derived object Base *b; boost::archive::binary_iarchive ia(...); ia.register_type(); ia >> b // Deseiralize to a base type pointer I have tried this but it does not work. Is there any way to make this work? Many thanks!!! -- View this message in context: http://boost.2283326.n4.nabble.com/Serialization-How-to-serialize-a-derived… Sent from the Boost - Users mailing list archive at Nabble.com.

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Boost Install fails?
by Dreamcat4 12 Apr '11

12 Apr '11

Hello, I am completely new to Boost framework. However like many others I am finding the initial stage(s) - namely that what is happening during the install seems particularly complicated. I guess most people here have been able to get going with Boost by glazing over the install and "it just works". Other people can run into a myriad of issues. So I guess my problem sits somewhere in-between those two extremes. One thing I cannot vouch for is not knowning (or wanting to know!) what boost is doing, and not seeing anywhere some firm list of requirements (eg system paths for libraries, etc) - I cannot be sure that my system has some misconfiguration somewhere that (is probably) causing this issue. However what is clear to me is that many other people can install boost on *their* systems with no apparent issue. So... whats the problem? In a nutshell, boost will only compile if i am UID=0 (root user / sudo superuser). As a normal, regular user boost install fails with the following error(s): janitors-Mac-mini:boost_1_46_1 id$ ./bootstrap.sh --show-libraries -n Building Boost.Jam with toolset darwin... Failed to build Boost.Jam Consult 'bootstrap.log' for more details bootstrap.log: https://gist.github.com/915620 It doesnt seem to matter the exact version of boost, or even the "CMake" version of boost. They all behave the same way. Whats unfortunate for me especially is that after successfully compiling jam (as root), and chown'ing down all the created files in the boost directory. The same error still seems to occur afterward. For example to compile such selected library. Has anyone seen anything like this? What could be the possible issue here? Is it really normal to compile everything as root?!!? Operating system - Mac OS-X Snow Leopard. Thanks in advance. dreamcat4 dreamcat4(a)gmail.com

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