April 2010 - Boost-users - lists.preview.boost.org

[Regex] Major performance difference between Boost.Regex and Linux regex library
by Kieran O'Donohoe 04 Apr '10

04 Apr '10

Hi, I am just starting to use Boost.Regex, porting from the Linux system regex library to Boost.Regex, and after doing initial testing on my first change I see a major performance impact, where Boost.Regex is about 30 times slower than the system regex library. The Boost.Regex documentation seems to imply that its performance has a positive comparsion with existing libraries so I expect that I am doing something wrong but can't see it. My regex strings are relatively short normal strings, e.g. "Authentication-Info", that is they contain no RE like syntax. The str passed to regex_search() (also tried regex_match()) can be an exact match to the regex, but may differ by case or surrounded by white space. Boost.Regex is used as follows: // I have a heap pointer to 44 boost::regex objects, all stored in a list // also associated with each boost::regex object is a function unique to each boost::regex* myRegex = new boost::regex("Authentication-Info", boost::regex::icase|boost::regex::nosubs); ... /* boost::regex_search() is called in a loop on the above list of boost::regex objects, for each test iteration there are 9 different values of name, all of which have a match in the above list, that is boost::regex_search() can be called up 396 times per test iteration, I performed a 1000 iteration test. */ // const char* name could be " authentication-info " and should match positively (and does) with the regex if(boost::regex_search(name, *myRegex, boost::match_nosubs)==true) { // do stuff on match - that is call associated function // then exit loop } I have also tried flags other than does listed, all with the same result. I put the test through a profiler and see that calls on match_results and sub_match are called a number of times (over 9 million) which makes me pretty sure that this is where the problem is, I don't need any match_results/sub_match, I just need validation that the string exists. Obviously a match needs to be made, but approx 51 match_results object constructions per search seems over the top. Fyi, here is an entry from the profiler output calling boost::regex_search() 186,000 times, which is expected: [5] 94.9 0.00 2.46 186000 bool boost::regex_search<char const*, char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >(char const*, char const*, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags) [5] But this entry where boost::match_results::match_results() is called 9,486,000 times is unexpected: [9] 35.3 0.18 0.73 9486000 boost::match_results<char const*, std::allocator<boost::sub_match<char const*> > >::match_results(std::allocator<boost::sub_match<char const*> > const&) [9] The same code executes 30 times faster if I replace new boost::regex(...) with a call to regcomp(&m_preg, "Authentication-Info", REG_EXTENDED | REG_ICASE) where m_preg is wrapped in a UDT that is heap allocated and likewise boost::regex_search(..) is replaced with a call to regexec() where nmatch is 0. _________________________________________________________________ Hotmail: Trusted email with powerful SPAM protection. https://signup.live.com/signup.aspx?id=60969

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Using type_trait-like functionality to detect incomplete types
by Michael Cox 04 Apr '10

04 Apr '10

I'm using googlemock to do some unit-testing via mock objects and I'm getting compiler errors on some of my mock methods. Because googlemock has some sophisticated meta-template programming techniques to allow it to print out the arguments passed to a mock method, I'm getting compiler errors on some of the methods that have incomplete types used as arguments. Is there anyway via boost::/tr1:: type_traits that I can detect this situation and have the gmock PrintTo template function just print "incomplete". I was hoping to find a nice "is_complete<T>" template function that would do the trick, but haven't found such a thing. Is it even possible to detect it without causing a compiler error? Michael

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[Function] requiring an exact match in function signature?
by Nathan Ridge 04 Apr '10

04 Apr '10

Hello, I'm wondering if there is a way to force boost::function to only accept functions/functors with the exact same signature. I need this because there are cases in my program where passing a function with a different but convertible signature is almost certainly an error, and it would really be nice if such uses triggered a compiler error. For instance, boost::function will readily convert a mutator function with this signature: T mutate(const T&) to a function with this signature: void mutate(T&) even though the two functions clearly have different semantics. I know I could force the signatures to be the same by simply using a plain function pointer, but I want to give the user the flexibility to pass in function objects (functors) as well. Any suggestions? Cheers, Nate. _________________________________________________________________ Got a phone? Get Hotmail & Messenger for mobile! http://go.microsoft.com/?linkid=9724464

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Spirit: simplified struct.cpp won't compile
by philip tucker 03 Apr '10

03 Apr '10

Why not? Thanks.

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[boost][serialization] Binary portable archive (eos implementation in Vault)
by Marc Perso 03 Apr '10

03 Apr '10

Hi all, Right now, we are involved in a development stage that requires data exchange between processes running on various operating systems, i.e. Windows XP 32bits <→ Windows Seven 64bits. We are using a TCP/IP communication protocol based on Boost∷Asio and Boost∷Serialization for that. In order to manage the portability of our data exchange (int, float, double,…), we have tried to use the binary portable archive posted by Christian Pfligersdorffer in Vault /Serialization but we are not able to use it; we are experiencing a lot of compilation errors. For illustrating this point, I’ve attached a very simple source file based on GPS example of Boost.Serialization: if the line #7 (#define PORTABLE_ARCHIVE) is commented the file compilation runs smoothly but with this “define” it fails. Our setup is the following: - Boost 1.40 - VC 7.1 - OS/WinXP I would like to know if someone around there has play with this portable implementation and how we must proceed. Any help? Best regards, Marc Viala

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[spirit,regex] Linking problems in VS 2008
by Adam Badura 03 Apr '10

03 Apr '10

I am using regex_p parser in Spirit. This uses Boost.Regex. The code compiles fine but does not link. Error messages are (debug mode, static linking, Boost 1.42): -------------------- 1>configuration.obj : error LNK2019: unresolved external symbol "public: void __thiscall boost::re_detail::raw_storage::resize(unsigned int)" (?resize@raw_storage@re_detail@boost@@QAEXI@Z) referenced in function "public: void * __thiscall boost::re_detail::raw_storage::extend(unsigned int)" (?extend@raw_storage@re_detail@boost@@QAEPAXI@Z) 1>configuration.obj : error LNK2019: unresolved external symbol "public: void * __thiscall boost::re_detail::raw_storage::insert(unsigned int,unsigned int)" (?insert@raw_storage@re_detail@boost@@QAEPAXII@Z) referenced in function "public: struct boost::re_detail::re_syntax_base * __thiscall boost::re_detail::basic_regex_creator<char,struct boost::regex_traits<char,class boost::cpp_regex_traits<char> > >::insert_state(int,enum boost::re_detail::syntax_element_type,unsigned int)" (?insert_state@?$basic_regex_creator@DU?$regex_traits@DV?$cpp_regex_traits@D@boost@@@boost@@@re_detail@boost@@QAEPAUre_syntax_base@23@HW4syntax_element_type@23@I@Z) 1>D:\Studies\Thesis\Debug\prover.exe : fatal error LNK1120: 2 unresolved externals -------------------- The interesting thing is that if I turn language extensions on (/Za option) in the project the problem disappears. How can this be solved? Adam Badura

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[Proto?][Phoenix?] : Advice on creating lazy data structures
by Manjunath Kudlur 03 Apr '10

03 Apr '10

With Phoenix or lambda-like DSELs implemented with Proto, it is easy to implement stuff when the expected actual parameters to the lambda expressions are primitive types. When I want to pass arbitrary types to the lambda expression and manipulate it in the lambda expression, things become complex. For example, consider the following function : struct point { float x; float y; }; float sum(point p) { return p.x+p.y; } If I want to have a lazy version of this function, I cannot simply do (arg1.x + arg1.y)(p). I have to implement functions that return Proto or Phoenix expressions and use it in the language. In the above case, it would look something like (point_get_x_(arg1) + point_get_y_(arg2))(p). So for every type I want to support in the DSEL, I have to implement lazy versions of functions to get and set the type members, or call some methods. In other words, the language has to be aware of all the data types that can be used with it. I am looking for some advice on a standard or a generic way for creating such lazy data structures. Has something like this been done before? I will be grateful for any pointers and suggestions. Thanks, Manjunath

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Boost Graph: edge indices
by Trevor Harmon 02 Apr '10

02 Apr '10

Hi, In the Boost Graph library, vertices have an index (vertex_index_t), and I was under the impression that edges have one, too. At least, there's a predefined type called edge_index_t. However, I can't figure out how to access an edge's index. For example, consider a graph defined like: typedef adjacency_list<vecS, vecS, directedS, Foo*> MyGraph; typedef graph_traits<MyGraph>::vertex_descriptor Vertex; typedef graph_traits<MyGraph>::edge_descriptor Edge; And let's say I've got a vertex descriptor called "u". I can iterate over u's outgoing edges like this: typedef graph_traits<MyGraph>::out_edge_iterator out_iter; std::pair<out_iter, out_iter> outp; for (outp = out_edges(u, g); outp.first != outp.second; ++outp.first) { Edge e = *outp.first; Vertex v = target(e, g); cout << index[v] << std::endl; // Works fine cout << index[e] << std::endl; // Compiler error } In this example, index[v] works as expected, but index[e] gives me a compiler error: "no match for ‘operator[]’ in ‘index[e]". Perhaps my graph typedef needs to be changed so that its edges have a property map for edge_index_t, although I'm not sure how to do that. (And anyway I wouldn't expect vertices to have indices by default but edges not...) Thanks for any help, Trevor

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begin, end and directory iterators
by Robert Jones 02 Apr '10

02 Apr '10

Do boost::begin() and boost::end() support directory iterators? ie., can you write void f(boost::filesystem::path&); boost::filesystem::path some_directory; std::for_each(boost::begin(some_directory), boost::end(some_directory), f); If they don't, could they and should they? - Rob.

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[1.43.0] Change of release schedule
by Beman Dawes 02 Apr '10

02 Apr '10

To allow a large block of weekend time for last tweaks, from now on the release schedule is going to be changed to the first Monday of the second month of each quarter. Updated calendar 1.43.0: http://www.boost.org/development/index.html General date info: http://svn.boost.org/trac/boost/wiki/ReleaseSchedule --Release managers

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