January 2012 - Boost-users - lists.boost.org

Re: [Boost-users] Needs advices on design ( mpl or processor )
by Alex Perry 07 Jan '12

07 Jan '12

On 07 January 2012 23:28 Alex Perry wrote:- > I've been following this thread despite being a total novice with mpl (and > template meta-programming in general). However I'm not quite sure why > you are trying to pass the offset through the templates in the 1st place - can't > you just use standard : syntax and let the compiler work out the offsets? Oops just read some more messages in the thread and now understand what you were trying to do (which wasn't what I was doing at all) Sorry for the noise Alex

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Re: [Boost-users] Needs advices on design ( mpl or processor )
by Alex Perry 07 Jan '12

07 Jan '12

On Sat 07/01/2012 08:42 Allan Nielsen <a(a)awn.dk> wrote:- >I will try to illustrate my design problem in a more simple example: > >struct TagA { > enum Size { size = 4 }; > enum E { A0 = 0, A1 = 1, A2 = 2, A3 = 3, }; }; > ... I've been following this thread despite being a total novice with mpl (and template meta-programming in general). However I'm not quite sure why you are trying to pass the offset through the templates in the 1st place - can't you just use standard : syntax and let the compiler work out the offsets? Eg enum A { A0,A1,A2,A3,A4 }; enum B { B0,B1,B2,B3,B4 }; template <typename type1, int t1_numbits, typename type2, int t2_numbits> struct packed { type1 first : t1_numbits; type2 second : t2_numbits; }; Obviously accessing members via a name like first is far from ideal and specifying the size in the template would make this really unusable. However at this point my lack of knowledge of mpl kicks in - I'm sure there is some clever way of coding this up so that packed<A,B,C> is defined like mpl::vector<> which could provide a clean way of accessing the members. My total naive first attempt using partial specialisations on member functions sort of works under MSVC but fails totally on gcc - not sure if this is because this is a MS extension or whether its C++11 and so would work on a newer gcc - it works with VS2010 and VS2008 (I don't think there are any C++0x extensions in 2008) on windows 7 and fails to compile with gcc 4.1.2 on Linux. Linux errors start with :- test.cpp:53: error: explicit specialization in non-namespace scope 'struct packed<type1, type2, type3, type4>' test.cpp:53: error: enclosing class templates are not explicitly specialized It's also relying on the (probably nearly always true) assumption that the enum types packed together would always be unique so that using the type of the enum can find the unique member - this assumption should at least have some sort of compile assertion on it (mpl again I guess). It seems like an awful lot of boiler plate code would have to live behind the scenes to make this anything like useable though so not sure its worth exploring as a possible method but just in case it helps :- #include <iostream> //An enum we want to be able to compress enum A{A0,A1,A2,A3,A4}; //The bit size information for enum as per previous example code (NB this is actually wrong 3 is big enough to hold 0-7 but heck ...) struct tagA { typedef enum A enum_type; enum { size=4 }; }; //Wrapper for above tag info just to save typeing having shown it done manually above template <typename enumType,int size_ = 4> struct tag { typedef enumType enum_type; enum { size=size_ }; }; //Another couple of enums and tag structures for bit sizes enum B{B0,B1,B2,B3,B4}; typedef tag<B,4> tagB; enum C{ C0,C1,C2,C3,C4 }; typedef tag<C,3> tagC; //Just to check that size is actually doing something enum D{ D0,D1,D2,D3,D4 }; typedef tag<D,4> tagD; //Our packed structure template <typename type1,typename type2, typename type3, typename type4 > struct packed { //Just for clarity typedef typename type1::enum_type first_type; typedef typename type2::enum_type second_type; typedef typename type3::enum_type third_type; typedef typename type4::enum_type fourth_type; typedef packed<type1,type2,type3,type4> thistype; //Our packed enums using the specified bit sizes first_type first : type1::size; second_type second : type2::size; third_type third : type3::size; fourth_type fourth : type4::size; //All following is just to provide a simple get/set syntax rather than accessing via member names struct fail {}; //Only used for general case - fail will not convert to T hence compile error when used template <typename T> T get() const { return fail; }; //Specialisations to provide access to the (unique) members based on their types template<> first_type get<first_type>() const { return first;} template<> second_type get<second_type>() const { return second;} template<> third_type get<third_type>() const { return third;} template<> fourth_type get<fourth_type>() const { return fourth;} //May as well define == using the get() - note extra specialisation for whole structure equality template <typename T> bool operator == (T const & other ) const { return get<T>() == other; } template <> bool operator ==<thistype>(thistype const & other ) const { return other==get<type1::enum_type>() && other==get<type2::enum_type>() && other==get<type3::enum_type>() && other==get<type4::enum_type>(); } template <typename T> void set(T val) { return fail; }; //Specialisations to provide access to the (unique) members based on their types template<> void set<first_type>(first_type val) { first = val;} template<> void set<second_type>(second_type val) { second = val;} template<> void set<third_type>(third_type val) { third = val;} template<> void set<fourth_type>(fourth_type val) { fourth = val;} //May as well define operator = for convenient syntax l template <typename T> T operator =(T val) { set<T>(val); return val; }; }; //Oh yuk but it would be nice to pass the actual enum names rather than the tag structure name into our template //I couldn't think of any easy way other than a macro but surely there is some neater solution. #define make_packed_type(A,B,C,D) packed<tag##A,tag##B,tag##C,tag##D> int main( int , char** ) { packed<tagA,tagB,tagC,tagD> test; make_packed_type(A,B,C,D) test2; //Try the macro version test.first = A3; //Using the specific member name test.set<B>( B4 ); //Using template specialisation of member function test.set( C1 ); //Same but using ADL test = D3; //ADL on operator = test2 = A3; test2 = B4; test2 = C1; test2 = D3; //Hmm having 2nd thoughts on this syntax - it's probably too confusing and unexpected to allow std::cout << "In test A is " << test.first << " B is " << test.get<B>() << " C is " << test.get<C>() << " D is " << test.get<D>() << std::endl; std::cout << "Sizeof of test is " << sizeof( test ) << std::endl; std::cout << "Piecewise equality check is" << " ==A3 " << ((test == A3)?"true":"false") << " ==B4 " << ((test == B4)?"true":"false") << " ==C1 " << ((test == C1)?"true":"false") << " ==D3 " << ((test == D3)?"true":"false") << std::endl; std::cout << "Overall equality check test == test2 is " << (( test == test2 )?"true":"false") << std::endl; return 0; } Which returns (on windows) In test A is 3 B is 4 C is 1 D is 3 Sizeof of test is 4 Piecewise equality check is ==A3 true ==B4 true ==C1 true ==D3 true Overall equality check test == test2 is true As I said before don't know if this is of any use whatsoever to you (but it allowed me to avoid doing some real work while playing!) - As shown in the output the size of the structure is 4 bytes so is packing the 4 enums down into 1 int (without the : syntax used the sizeof this structure is 16 bytes) Alex

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boost ASIO/serialisation with different boost version. Bug or feature ?
by Avi Bahra 07 Jan '12

07 Jan '12

Currently I have built a client/server that uses ASIO with boost serialization. I built one set with boost 1.45 and another with boost 1.47 However: o start boost 1.45 server o ping using 1.47 client I get a boost::archive::archive_exception unsupported version o start boost 1.47 server o ping with boost 1.45 client Again I get a boost::archive::archive_exception unsupported version Given that there was no change in format of the ping, is this bug or feature ? Is there any way of disabling this feature of the archive , so exception is only thrown when there is format change? Any help appreciated. Ta, Avi

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Register variadic template as tags in a boost::mpl::map
by Allan Nielsen 07 Jan '12

07 Jan '12

In the following code, why can't I look up BB and CC in the mpl::map type_map? I would expect the map to look like this: map < pair<AA, A< xx > >, pair<BB, B< xx > >, pair<CC, C< xx > > > But it does not seem like this is the case... #include <iostream> #include <boost/type_traits/is_same.hpp> #include <boost/mpl/map.hpp> #include <boost/mpl/at.hpp> #include <boost/mpl/insert.hpp> struct AA {}; struct BB {}; struct CC {}; template<int OFFSET> struct A { typedef AA T; enum O { offset = OFFSET }; enum S { size = 2 }; }; template<int OFFSET> struct B { typedef AA T; enum O { offset = OFFSET }; enum S { size = 4 }; }; template<int OFFSET> struct C { typedef AA T; enum O { offset = OFFSET }; enum S { size = 4 }; }; template < template <int> class Head, template <int> class... Tail> struct X : public Head< X<Tail...>::size * X<Tail...>::offset >, public X<Tail...> { typedef Head< X<Tail...>::size * X<Tail...>::offset > _Head; enum O { offset = X<Tail...>::size * X<Tail...>::offset }; enum S { size = _Head::size * X<Tail...>::size }; typedef typename boost::mpl::insert < typename X<Tail...>::type_map, boost::mpl::pair<typename _Head::T, _Head > >::type type_map; template <typename T> int get_offset() { return boost::mpl::at<type_map, T>::type:: offset; } }; // base case template < template <int> class Head> struct X<Head> : public Head<1> { enum O { offset = Head<1>::offset }; enum S { size = Head<1>::size }; typedef boost::mpl::map< boost::mpl::pair< typename Head<1>::T, Head<1> > > type_map; }; int main() { X< A, B, C > x1; std::cout << x1.get_offset<CC>() << std::endl; // generates compile errors //std::cout << x1.get_offset<BB>() << std::endl; //std::cout << x1.get_offset<CC>() << std::endl; return 0; }

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[BGL] getting an edge_descriptor of a reverse_graph
by Alex Hagen-Zanker 06 Jan '12

06 Jan '12

I upgraded from boost 1.45 to 1.48 and there are some breaking changes related to reverse_graph The main problem that I encounter is that boost::edge(u ,v, graph) returns a edge_descriptor to the graph that underlies reverse_graph, rather than reverse_graph itself . The following therefore does not compile: template<typename Graph> void foo(Graph& graph) { boost::graph_traits<Graph>::edge_descriptor e = boost::edge(0, 1, graph).first; } int main() { boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS> graph(2); foo(graph); // this line compiles foo(boost::make_reverse_graph(graph)); // this line does not compile } Do you have suggestions how to rewrite foo(Graph& graph) in order to generically work for both plain and reversed graphs? For now I have rewritten the boost::edge function in reverse_graph.hpp to return a pair<reverse_graph_edge_descriptor, bool> but that does not seem right. Thanks, Alex

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unexpected behaviour of filtering_ostream
by Ed Keith 06 Jan '12

06 Jan '12

I have the following code: int main(int argc, char *argv[]) { io::filtering_ostream out; out.push(std::cout); out << "this is a test" << endl; out << std::cin.rdbuf(); } when I run it the string "this is a test" gets sent to cout, but input type into cin does not get echoed to cout. Can anyone clue my in as to why not? -EdK Ed Keith e_d_k(a)yahoo.com Blog: edkeith.blogspot.com

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building boost.log on OSX 10.7.2 with boost 1_48
by Chris Bartlett 06 Jan '12

06 Jan '12

Hi all, I'm trying to build boost.log. I had it built and working against boost 1_47. I now have a clean 1_47 install on OSX (10.7.2) and I pulled boost.log from the trunk in sourceforge: https://boost-log.svn.sourceforge.net/svnroot/boost-log/trunk/ but when I build it, it reports that it needs 1_48. no problem - i'l build a boost 1_48 install and try that… boost 1_48 installed fine. I downloaded the boost.log from trunk and updated my kit and ran: ./bootstrap.sh -with-libraries=log --prefix=/usr/local --includedir=/usr/local/include --libdir=/usr/local/lib followed by: sudo ./b2 and I get the following: ...found 2606 targets... ...updating 9 targets... darwin.compile.c++ bin.v2/libs/log/build/darwin-4.2.1/release/threading-multi/tick_count.o libs/log/src/tick_count.cpp:220:5: error: #error Boost.Log: POSIX timers not supported on your platform "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -dynamic -no-cpp- precomp -gdwarf-2 -fexceptions -fPIC -DBOOST_ALL_NO_LIB=1 DBOOST_DATE_TIME_DYN_LINK=1 - DBOOST_FILESYSTEM_DYN_LINK=1 -DBOOST_LOG_BUILDING_THE_LIB=1 -DBOOST_LOG_DLL - DBOOST_LOG_USE_NATIVE_SYSLOG=1 -DBOOST_SYSTEM_DYN_LINK=1 -DBOOST_THREAD_POSIX - DBOOST_THREAD_USE_DLL=1 - DDATE_TIME_INLINE -DNDEBUG -I"." -c -o "bin.v2/libs/log/build/darwin-4.2.1/release/threading-multi/tick_count.o" "libs/log/src/tick_count.cpp" Anyone shed any light on this? has the latest version of boost.log not been built on OSX lion? any help gratefully received, Chris

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boost test: link time errors/regressions with boost 1.47 test
by Avi Bahra 06 Jan '12

06 Jan '12

I have been using/linking with boost test, 1.39 -->1.45 Boost unit-test has been very robust on the whole However migrating to 1.47 I am getting links errors of the form: ld: 0711-317 ERROR: Undefined symbol: .boost::unit_test::ut_detail::auto_test_unit_registrar::auto_test_unit_registrar(boost::unit_test::basic_cstring<const char>) ld: 0711-317 ERROR: Undefined symbol: .boost::unit_test::unit_test_log_t::set_checkpoint(boost::unit_test::basic_cstring<const char>,unsigned long,boost::unit_test::basic_cstring<const char>) ld: 0711-317 ERROR: Undefined symbol: .boost::test_tools::tt_detail::check_impl(const boost::test_tools::predicate_result&,const boost::unit_test::lazy_ostream&,boost::unit_test::basic_cstring<const char>,unsigned long,boost::test_tools::tt_detail::tool_level,boost::test_tools::tt_detail::check_type,unsigned long,...) ld: 0711-317 ERROR: Undefined symbol: .boost::unit_test::ut_detail::normalize_test_case_name(boost::unit_test::basic_cstring<const char>) ld: 0711-317 ERROR: Undefined symbol: .boost::unit_test::test_case::test_case(boost::unit_test::basic_cstring<const char>,const boost::unit_test::callback0<boost::unit_test::ut_detail::unused>&) The problem is on AIX 5.3. using v11.1 compiler linking with libboost_unit_test_framework-mt-d.a has always worked in the past. The library compiles and links without any errors on other platforms like HPUX/acc,linux32/gcc,linux64/gcc Any help appreciated Best regards, Ta, Avi

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Get All Words Offset in String using Boost regex
by S Nagre 06 Jan '12

06 Jan '12

Hello, I wish to determine the "start" and "length" of all the completed words in a string using Boost Regex For example I have a String "*Hello World and Google*" I would like to create a map like this... 1, 5 //First Character position and Length of Word "Hello" 7, 5 // First Character position and Length of Word World 14, 3 //First Character position and Length of Word "And" 18, 6 // First Character position and Length of Word "Google" This is the code I have written.. void CreateOffSetMap(std::string completeInStr) { std::map<int32, int32>OffSetMap; std::string escapeChar = "\\" ; std::string bChar = "b"; std::string dotChar = "."; std::string findWordInStr = escapeChar + bChar + dotChar + escapeChar + bChar; boost::regex regExpression(findWordInStr); boost::smatch what; std::string::const_iterator start = completeInStr.begin(); std::string::const_iterator end = completeInStr.end(); while (boost::regex_search(start, end, what, regExpression)) { int32 foundPos = what.position(); int32 foundLen = what.length(); int32 endOffSet = startOffSet + foundLen; std::string foundString(start + foundPos, start + foundPos + foundLen); OffSetMap[foundPos] = foundLen; start += foundPos + foundLen; } } But is not working correct as expected, Could Anyone tell me where I am doing wrong here ? Thanks in Advance Subhash

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[Graph] need suggestion
by srinivas boppu 06 Jan '12

06 Jan '12

Hello All, I need a graph structure as follows. (Here my input is a Graph which I call it as " Control Flow Graph".) On this "Control Flow Graph", I run a algorithm it creates another graph, and on that I will run again the algorithm, it will create another "Graph" and it continues until it become a "Single Node". I should be able to access all the Graphs in each stage and my original graph information should be untouched. What is the best way to do it ? Any suggestions ? (Actually, I am trying to solve one problem using "Interval Based Analysis" of Control Flow Graphs. I would like to divide the given main control flow graph into disjoint intervals. You can have a look at the following link for more information http://nptel.iitm.ac.in/courses/106108052/module9/control-flow-ana-2.pdf ) Regards, Srinivas

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