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[spirit] working with end_p
by james.jones＠firstinvestors.com 07 Jul '06

07 Jul '06

From: Neil Hunt <boost(a)thehunts.id.au> > Hello all, > > Given a simple spirit grammar (simplified from my real grammer and > untested) such as: > > file = *line; > line = sensible_line >> ending >> *comment; > sensible_line = confix_p( '\"', *c_escape_ch_p, '\"' ); > comment = !( ch_p(';') >> ( anychar_p - eol_p ) ) >> ending; > ending = *blank_p >> ( eol_p | end_p ); > > > Note: any given line can be legitimately terminated by the end of the > file or end of line > > And there can be arbitrary numbers of comment lines between sensible lines. > > However since 'comment' is terminated with 'ending', the parser ends up > in an infinite loop matching the kleene star on end_p because it returns > zero length (doesn't advance the scanner). At least I think this is the > problem. Indeed. You can fix it by adjusting your grammar thus: line = sensible_line >> (ending >> comment)* >> ending; sensible_line ... as before comment = !( ch_p(';') >> ( anychar_p - eol_p ) ); ending ... as before - James Jones Administrative Data Mgmt. Webmaster 375 Raritan Center Pkwy, Suite A Data Architect Edison, NJ 08837

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[serialization] Facets for writing and reading infinity and nan to text streams
by Johan Råde 07 Jul '06

07 Jul '06

Following a suggestion of Robert Ramey's, I have put together facets for writing and reading non-finite floating point numbers, such as infinity and nan, to text streams, in a consistent and portable way. This is useful when serializing to text archives, but should have other applications as well. I have attached a zip file. It contains three files: 1. the actual code: non_finite_num_facets.hpp 2. documentation: non_finite_num_facets_doc.txt 3. tests: non_finite_num_facets_test.cpp The code handles char and wchar_t. It handles float, double and long double. The code has been tested with VC++ 7.1 but should work with other compilers as well. Any feedback is wellcome. --Johan Råde (rade(a)maths.lth.se)

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std::find_if, boost::mem_fn and boost::not1
by Pete Hodgson 06 Jul '06

06 Jul '06

Hi All, I'm just getting into using boost and stl algorithms, and I'm getting some indecipherable compiler errors that I'd like some help understanding. Here's some sample code: <------------------------SNIP------------------------> #include <boost/shared_ptr.hpp> #include <boost/functional.hpp> #include <boost/bind.hpp> class CEgg { public: bool IsHatched() const; }; typedef std::vector< boost::shared_ptr<CEgg> > tEggsVector; //this function compiles with no problems bool SomeEggsHaveHatched() { tEggsVector basketOfEggs; tEggsVector::const_iterator it = std::find_if( basketOfEggs.begin(), basketOfEggs.end(), boost::mem_fn( &CEgg::IsHatched ) ); bool bSomeEggsHaveHatched = ( it != basketOfEggs.end() ); return bSomeEggsHaveHatched; } //this function doesn't compile, //presumably because of the boost::not1 usage bool AllEggsHaveHatched() { tEggsVector basketOfEggs; tEggsVector::iterator it = std::find_if( basketOfEggs.begin(), basketOfEggs.end(), boost::not1( boost::mem_fn( &CEgg::IsHatched ) ) ); bool bSomeEggsHaventHatched = ( it != basketOfEggs.end() ); return !bSomeEggsHaventHatched; } <------------------------SNIP------------------------> When I try and compile this in Visual C++ 2003 I get the following compile errors for AllEggsHaveHatched(): c:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\algorithm(64) : error C2664: 'bool boost::unary_negate<Predicate>::operator ()(const boost::call_traits<T>::param_type) const' : cannot convert parameter 1 from 'std::allocator<_Ty>::value_type' to 'const boost::call_traits<T>::param_type' with [ Predicate=boost::_mfi::cmf0<bool,CEgg>, T=boost::unary_traits<boost::_mfi::cmf0<bool,CEgg>>::argument_type ] and [ _Ty=boost::shared_ptr<CEgg> ] and [ T=boost::unary_traits<boost::_mfi::cmf0<bool,CEgg>>::argument_type ] No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called c:\WORK\4DCapture_Soln\VideoCapture\PixelinkCaptureFacade.h(46) : see reference to function template instantiation '_InIt std::find_if<std::vector<_Ty>::iterator,boost::unary_negate<Predicate>>(_InIt,_InIt,_Pr)' being compiled with [ _InIt=std::vector<boost::shared_ptr<CEgg>>::iterator, _Ty=boost::shared_ptr<CEgg>, Predicate=boost::_mfi::cmf0<bool,CEgg>, _Pr=boost::unary_negate<boost::_mfi::cmf0<bool,CEgg>> ] Any idea why boost::not1 seems to be causing problems? Should I be using std::not1? or boost::mem_fun instead of boost:mem_fn? Cheers and TIA, Pete

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Boost compile fails on Visual C++ 6, warnings on VS8
by Sagnes, Frederic 06 Jul '06

06 Jul '06

Hello, I'm using the Boost libraries for my project (archive, threads, program_options, date_time) and these are really helpful, saved me a lot of time and the great designs make them easy to use. I'm compiling my project with Visual Studio 2005 (8.0) and gcc 4.0.1. Both work quite well, I only have warnings on VS8 because it seems to render integer operation in 64 bit and no cast is being done (a static cast would fix this), some deprecation warning which are normal, and the GCC build works well. But the VC++ 6 compilation is a real pain, here is the command line for BJam: bjam "-sTOOLS=msvc" "-sMSVC_ROOT=C:\Programme\Microsoft Visual Studio\VC98" "-sVISUALC=C:\Programme\Microsoft Visual Studio\VC98" --prefix=D:\ALM\Boost\msvc install I get a lot of compilation errors, including internal compiler errors which are quite alarming. I thought Boost libraries were meant to be portable and compile on VS6. The archive library for instance fails to build. Is there a workaround to build Boost libraries on VS6? Did I miss a switch or setting? Is VS6 that bad that it can't render complex but standard C++ code? Where can I check with which compiler Boost libraries are compatible? Best regards _______________________________________________ Frédéric Sagnes, A&D AS RD DH K3 Siemens AG Karlsruhe

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boost::bind question
by Surya Kiran Gullapalli 06 Jul '06

06 Jul '06

Hi, I've a std::map with the following structure. std::map < int, tuple<std::string, std::string> > mapTuple ; typedef map < int, tuple<string, string> > mapTuple ; Now i've say 10 elements in this container. Now i'd like to iterate thru this container and find a specific element which matches a certain criteria. Right now I'm doing this. MapIntTuple::iterator iter ; for (iter = mymap.begin(); iter != mymap.end(); ++iter) { if (iter->second.get<0>() == current_field) break ; } I'd like to iterate thru the container and find the element whose first string in the tuple matches with my search string. How can i do this using boost::lamdba::bind and std::find_if. May be that will help me in understanding boost::bind better. iter = find_if (mymap.begin(), mymap.end(), ???) ; Thanks in advance, Surya

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[date_time] unused parameter warnings with gcc
by Brian Neal 05 Jul '06

05 Jul '06

Just a suggestion: We like to compile with lots of warning turned on and try to strive for warning free builds. Under gcc, with the -Wall -W options, we get a lot of "warning: unused parameter" warnings with the date_time library. For example, /usr/include/boost-1_33/boost/date_time/time_facet.hpp:202: warning: unused parameter 'a_ref' It looks like a lot of these could be fixed by /* commenting out */ the unused parameter names; e.g. explicit time_facet(::size_t /* a_ref */ = 0) ... Thanks.

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Re: [Boost-users] [boost] [Announce] Boost Installer for Visual C++ 7.1/8.0
by Trent Nelson 05 Jul '06

05 Jul '06

> Boost Consulting is pleased to announce the availability of a Windows > installer for the current Boost release (1.33.1). See: > > http://www.boost-consulting.com/download.html Any plans to make the .nsi file you're using public? There may be a few of us out there that have experience with Nullsoft and could contribute to the installer in some way, shape or form. Trent.

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vectors with multiindex
by Adán Cosgaya 05 Jul '06

05 Jul '06

hi, i am new using the multiindex library, and I need to do the following. I have a set of d-dimensional points (e.g (3,5,8,9,5) is a 5-dimensional point), and I need to sort the points on each of the coordinates. I want to store the points in a vector, and use multiindex to have all the points (vectors in this case) sorted in each of the coordinates. E.g. sorted by x: x y z w ----------- 0 0 0 0 1 2 7 4 2 3 1 1 3 1 3 3 4 5 2 9 sorted by y: 0 0 0 0 3 1 3 3 1 2 7 4 2 3 1 1 4 5 2 9 etc... would you mind pointing me in the right direction with an example of how to do it with multiindex library? thanks

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[mpl] a few questions about set and map
by Yuval Ronen 05 Jul '06

05 Jul '06

I spent some time reading the mpl docs, and I have a few questions about mpl::set and mpl::map. 1. The docs assert there is a 'front' algorithm for set and map. This sounds weird to me, as the order of the types is them unspecified. But if I'm wrong, and 'front' is in place, then where is 'back'? 2. Where's multiset and multimap? In the boost/mpl directory I see something about multiset, but no real boost/mpl/multiset.hpp header, and there's absolutely nothing about multimap. 3. The docs say that the size of joint_view is the arithmetic sum of the sizes of the sequences of which it's composed. Is that true also in the case of set/map? For an mpl newbie it sounds reasonable that it will removed duplicates and might end up with a size that is smaller than the sum of its components. If it's not, then it sounds quite useless to use it for set/map. Thanks, Yuval

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How to find ancestor nodes in a graph, thanks
by sean yang 05 Jul '06

05 Jul '06

Hi folks, I want to find all the nodes that can reach a specific node 'target_n'. Let's say, an example graph looks like this: G= (V, E), where V={A, B, C, target_1, target_2, D, E, F}, and E= { (A-->B), (B-->target_1), (C-->target_2), (A-->target_2), (D-->E), (E-->F), (F-->D), } In this example, I want to find out(say print them out) 'A', 'B', 'C'. Now, I have a graph representation like the following one . ------------------------------ typedef adjacency_list<vecS, vecS, bidirectionalS, VertexNameProperty > Graph; Graph travel; --------------------------------- And I have already read in the above information to the Graph travel. One way I am thinking of to achieve the above goal is: reverse the direction of edges in G, i.e., getting a G', first; and then do BFS from target_n nodes. My question is: (1) is there an easy (some API, sorry I am not familar with the library) way to reverse edge direction? (2) is there an easy way to add a 'printf()' during BFS? Thanks, Sean _________________________________________________________________ FREE pop-up blocking with the new MSN Toolbar get it now! http://toolbar.msn.click-url.com/go/onm00200415ave/direct/01/

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