January 2005 - Boost-users - lists.boost.org

Boost::filesystem : possible addition
by Georgios Diamantopoulos 05 Jan '05

05 Jan '05

Hello, I've always wanted some functionality to determine the relative path between two paths. Maybe something like this can be added to the convinience.hpp or otherwise: fs::path relative_path_of(fs::path const &base, fs::path const &full) { std::string fullStr = full.string(); std::string baseStr = base.string() + "/"; // add a slash so that it returns the relative path boost::erase_first(fullStr, baseStr); return fs::path(fullStr); } Cheers, Georgios

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Problem serializing (restoring) through base pointer
by Bill Lear 05 Jan '05

05 Jan '05

I have spent several hours combing the documentation and archives, but can't seem to find an answer to my problem. I have an abstract base class, Operation with a pure virtual function 'double value() = 0'. I derive a class, BinaryOperation from Operation. It takes as arguments an operation type (+, -, *, /) and two Operation pointers --- one for the left operand, one for the right. It stores these two pointers internally and uses them when the value() method is invoked. I derive two more classes from Operation, trivial, made-up, useless ones. One is called IncrementOperation, one is called DecrementOperation. I can save to an XML archive properly, but when I try to restore, it core dumps. I am running gcc-3.2. I have tried everything I can think of, but am stuck. I have tried using polymorphic_xml_iarchive (and corresponding output version), but it still fails. The first few stack frames from GDB are: #0 0x0808897f in ?? () #1 0x08052f7d in boost::archive::detail::basic_iarchive::load_pointer(void*&, boost::archive::detail::basic_pointer_iserializer const*, boost::archive::detail::basic_pointer_iserializer const* (*)(boost::serialization::extended_type_info const&)) () #2 0x0804c78a in boost::archive::detail::load_pointer_type<boost::archive::xml_iarchive, Operation*>::invoke(boost::archive::xml_iarchive&, Operation*&) ( ar=@0xbffff0e0, t=@0xbffff330) at /usr/local/include/boost-1_32/boost/archive/detail/iserializer.hpp:450 #3 0x0804c51a in load<boost::archive::xml_iarchive, Operation*> ( ar=@0xbffff0e0, t=@0xbffff330) at /usr/local/include/boost-1_32/boost/archive/detail/iserializer.hpp:529 Following my sig, I've posted the xml input file that is generated by the save, and then following that, the C++ code (fairly short). It is failing on the following line: ia & BOOST_SERIALIZATION_NVP(t); Any help would be appreciated. Thanks. Bill <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="3"> <t class_id="1" class_name="BinaryOperation" tracking_level="1" version="0" object_id="_0"> <Operation class_id="0" tracking_level="1" version="0" object_id="_1"></Operation> <_op>42</_op> <_left_operand class_id_reference="1" object_id="_2"> <Operation object_id="_3"></Operation> <_op>43</_op> <_left_operand class_id="2" class_name="IncrementOperation" tracking_level="1" version="0" object_id="_4"> <Operation object_id="_5"></Operation> <_init>33</_init> </_left_operand> <_right_operand class_id="3" class_name="DecrementOperation" tracking_level="1" version="0" object_id="_6"> <Operation object_id="_7"></Operation> <_init>333</_init> </_right_operand> </_left_operand> <_right_operand class_id_reference="1" object_id="_8"> <Operation object_id="_9"></Operation> <_op>45</_op> <_left_operand class_id_reference="3" object_id="_10"> <Operation object_id="_11"></Operation> <_init>444</_init> </_left_operand> <_right_operand class_id_reference="2" object_id="_12"> <Operation object_id="_13"></Operation> <_init>44</_init> </_right_operand> </_right_operand> </t> </boost_serialization> #include <string> #include <iomanip> #include <iostream> #include <fstream> #include <stdexcept> #include <boost/serialization/nvp.hpp> #include <boost/archive/xml_iarchive.hpp> #include <boost/archive/xml_oarchive.hpp> //#include <boost/archive/polymorphic_xml_iarchive.hpp> //#include <boost/archive/polymorphic_xml_oarchive.hpp> #include <boost/serialization/export.hpp> class Operation { public: Operation() { } virtual ~Operation() { } virtual double value() = 0; private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int /* file_version */){ } }; BOOST_IS_ABSTRACT(Operation); class BinaryOperation: public Operation { public: BinaryOperation() : _op(' '), _left_operand(0), _right_operand(0) { } BinaryOperation(char op, Operation* left_operand, Operation* right_operand) : _op(op), _left_operand(left_operand), _right_operand(right_operand) { } virtual ~BinaryOperation() { } virtual double value() { switch (_op) { case '+': return _left_operand->value() + _right_operand->value(); break; case '-': return _left_operand->value() - _right_operand->value(); break; case '*': return _left_operand->value() * _right_operand->value(); break; case '/': return _left_operand->value() / _right_operand->value(); break; } } protected: char _op; Operation* _left_operand; Operation* _right_operand; friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int /* file_version */){ ar & BOOST_SERIALIZATION_BASE_OBJECT_NVP(Operation) & BOOST_SERIALIZATION_NVP(_op) & BOOST_SERIALIZATION_NVP(_left_operand) & BOOST_SERIALIZATION_NVP(_right_operand); } }; BOOST_CLASS_EXPORT_GUID(BinaryOperation, "BinaryOperation"); class IncrementOperation : public Operation { public: IncrementOperation() : _init(0) { } IncrementOperation(double init) : _init(init) { } virtual double value() { return _init++; } protected: double _init; friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int /* file_version */){ ar & BOOST_SERIALIZATION_BASE_OBJECT_NVP(Operation) & BOOST_SERIALIZATION_NVP(_init); } }; BOOST_CLASS_EXPORT_GUID(IncrementOperation, "IncrementOperation"); class DecrementOperation : public Operation { public: DecrementOperation() : _init(0) { } DecrementOperation(double init) : _init(init) { } virtual double value() { return _init--; } protected: double _init; friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int /* file_version */){ ar & BOOST_SERIALIZATION_BASE_OBJECT_NVP(Operation) & BOOST_SERIALIZATION_NVP(_init); } }; BOOST_CLASS_EXPORT_GUID(DecrementOperation, "DecrementOperation"); void save_Operation(const Operation* t) { std::ofstream ofs("operation.xml"); assert(ofs.good()); boost::archive::xml_oarchive oa(ofs); //boost::archive::polymorphic_xml_oarchive oa(ofs); oa & BOOST_SERIALIZATION_NVP(t); } void restore_Operation(Operation*& t) { std::ifstream ifs("operation.xml"); if (!ifs.good()) { throw std::runtime_error("No input archive file"); } boost::archive::xml_iarchive ia(ifs); //boost::archive::polymorphic_xml_iarchive ia(ifs); std::cout << "Reading ...\n"; ia & BOOST_SERIALIZATION_NVP(t); std::cout << "Done reading ...\n"; } int main(int, char *[]) { try { Operation* a = new BinaryOperation('+', new IncrementOperation(33), new DecrementOperation(333)); Operation* b = new BinaryOperation('-', new DecrementOperation(444), new IncrementOperation(44)); Operation* c = new BinaryOperation('*', a, b); save_Operation(c); Operation* new_c; std::cout << "Restoring\n"; restore_Operation(new_c); } catch (std::exception e) { std::cerr << e.what() << '\n'; return 1; } return 0; }

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why doesn't scoped_ptr have a custom deleter?
by Pablo Aguilar 04 Jan '05

04 Jan '05

Hi, I'm currently playing around with Apache's Xerces XML library, and found myself needing to ->release some pointers. shared_ptr + mem_fn works great: shared_ptr<DOMBuilder> db( impl->createBuilder() , mem_fn(&DOMBuilder::release) ); But for the objects I'm using, I don't need a shared_ptr, but just a scoped_ptr. So I'm wondering about the rationale behind not giving scoped_ptr a custom deleter? Is it that shared_ptr's overhead is negligible (when not being shared I mean)? thanks

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Boost.Serialization problems in VC 7.1
by James Trotter 04 Jan '05

04 Jan '05

Hi, I'm trying to get the boost.serialization library to work, but I'm having some problems. I'm running VC 7.1, and I've tried both boost 1.32, and the latest CVS. I manage to compile and install the library, but when I try to compile and run the demo application that comes with it, I get a runtime error. It's compiling and linking perfectly, but at runtime I get a message box saying: "Unhandled exception at 0x7c59bbf3 in Test.exe: Microsoft C++ exception: __non_rtti_object @ 0x0012f8b0." Anyone had a problem like this before? Anyone know how to fix it?

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thread::thread() in Windows
by Yuval Ronen 04 Jan '05

04 Jan '05

Hi. I believe that there is a bug in thread::thread() under Windows. The code uses GetCurrentThread() WinAPI function, but this is not enough. If you'll try to create such a thread object, and pass its reference to another thread which will join it - something like struct SomeThread { thread *m_thread; SomeThread(thread *a_thread) : m_thread(a_thread) { } void operator()() { do_some_work() m_thread->join(); delete m_thread; } }; { ...somewhere in the code... SomeThread st(new thread()); thread other_thread(st); } then it won't work. The following is a quote from MSDN about GetCurrentThread(): "The return value is a pseudo handle for the current thread... A pseudo handle is a special constant that is interpreted as the current thread handle... The function cannot be used by one thread to create a handle that can be used by other threads to refer to the first thread. The handle is always interpreted as referring to the thread that is using it. A thread can create a "real" handle to itself that can be used by other threads, or inherited by other processes, by specifying the pseudo handle as the source handle in a call to the DuplicateHandle function." The conclusion is that a call to DuplicateHandle() is needed after GetCurrentThread(). Thanks, Yuval

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[MPL] map question
by David Greene 04 Jan '05

04 Jan '05

I'm not understanding something about the interaction of map with the algorithms. I've got a map whose value_type is another map. I'd like to iterate through the map entries and add all the "sub-map" entries to the "primary" map. I wrote a little testcase, attached below. When I compile it with g++ 3.3.3, I get this: boost-1_32/boost/mpl/pair.hpp: In instantiation of `boost::mpl::second<mpl_::_2>': fold2.cc:23: instantiated from `boost::mpl::value_type_impl<boost::mpl::aux::map_tag>::apply<map_types, mpl_::_2>' fold2.cc:23: instantiated from `boost::mpl::value_type<map_types, mpl_::_2>' fold2.cc:23: instantiated from here boost-1_32/boost/mpl/pair.hpp:56: error: no type named `second' in `struct mpl_::_2' fold2.cc:23: error: `types' is not a member of type ` boost::mpl::value_type<map_types, mpl_::_2>' fold2.cc:24: error: template argument 1 is invalid fold2.cc:24: error: ISO C++ forbids declaration of `type name' with no type boost-1_32/boost/mpl/aux_/preprocessed/gcc/fold_impl.hpp: In instantiation of `boost::mpl::apply_wrap2<int, map_types, boost::mpl::pair<key1, entry> >': boost-1_32/boost/mpl/aux_/preprocessed/gcc/fold_impl.hpp:49: instantiated from `boost::mpl::apply2<int, map_types, boost::mpl::pair<key1, entry> >' boost-1_32/boost/mpl/aux_/preprocessed/gcc/fold_impl.hpp:49: instantiated from `boost::mpl::aux::fold_impl<1, boost::mpl::m_iter<map_types, 2, 3>, boost::mpl::m_iter<map_types, 3, 3>, map_types, int>' boost-1_32/boost/mpl/fold.hpp:39: instantiated from `boost::mpl::fold<map_types, map_types, int>' fold2.cc:24: instantiated from here boost-1_32/boost/mpl/aux_/preprocessed/gcc/fold_impl.hpp:49: error: ` int' is not a class, struct, or union type boost-1_32/boost/mpl/aux_/preprocessed/gcc/fold_impl.hpp: In instantiation of `boost::mpl::aux::fold_impl<1, boost::mpl::m_iter<map_types, 2, 3>, boost::mpl::m_iter<map_types, 3, 3>, map_types, int>': boost-1_32/boost/mpl/fold.hpp:39: instantiated from `boost::mpl::fold<map_types, map_types, int>' fold2.cc:24: instantiated from here boost-1_32/boost/mpl/aux_/preprocessed/gcc/fold_impl.hpp:49: error: no type named `type' in `struct boost::mpl::apply2<int, map_types, boost::mpl::pair<key1, entry> >' boost-1_32/boost/mpl/aux_/preprocessed/gcc/fold_impl.hpp: In instantiation of `boost::mpl::aux::fold_impl<1, boost::mpl::m_iter<map_types, 2, 3>, boost::mpl::m_iter<map_types, 3, 3>, map_types, int>': boost-1_32/boost/mpl/fold.hpp:39: instantiated from `boost::mpl::fold<map_types, map_types, int>' fold2.cc:24: instantiated from here boost-1_32/boost/mpl/aux_/preprocessed/gcc/fold_impl.hpp:53: error: no type named `type' in `struct boost::mpl::apply2<int, map_types, boost::mpl::pair<key1, entry> >' boost-1_32/boost/mpl/fold.hpp: In instantiation of `boost::mpl::fold<map_types, map_types, int>': fold2.cc:24: instantiated from here boost-1_32/boost/mpl/fold.hpp:39: error: no type named `state' in `struct boost::mpl::aux::fold_impl<1, boost::mpl::m_iter<map_types, 2, 3>, boost::mpl::m_iter<map_types, 3, 3>, map_types, int>' fold2.cc:24: error: syntax error before `;' token fold2.cc:26: error: syntax error before `::' token An EDG-based compiler gives much the same error. What am I doing wrong? Much thanks for the help! -Dave #include <boost/mpl/fold.hpp> #include <boost/mpl/placeholders.hpp> #include <boost/mpl/copy.hpp> #include <boost/mpl/map.hpp> #include <boost/mpl/value_type.hpp> #include <boost/mpl/inserter.hpp> #include <boost/mpl/insert.hpp> #include <boost/mpl/pair.hpp> using namespace boost; using namespace boost::mpl; struct key1 {}; struct key2 {}; struct entry { typedef map<pair<key2, int> > types; }; typedef map<pair<key1, entry> > map_types; typedef fold<map_types, map_types, copy<value_type<map_types, _2>::types, inserter<_1, insert<_1, _2> > > >::type result; result::blah; // Get a printout

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Serialization demo.
by Ken Perry 03 Jan '05

03 Jan '05

has anyone been able to get demo_xml.cpp to compile using mingw in either cygwin, msys, or just at the regular command line in XP pro? If you ahve what is the command line you used to compile it. I haven't been able to find a Jamfile or a Makefile for them so I have been trying to figure out the correct libraries to link with it and am having no luck. Ken

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[Regex] How to match the "End of buffer"/"End of string"?
by jordi 03 Jan '05

03 Jan '05

Hi, I'm new in regex and this is my first post, so maybe the solution is obvious but I couldn't find it in google... I need to parse the multiline output of a command, every line ends with a \n except the last one, which actually it ends with the end of buffe ("\0" character). The output I need to parse is something like: "text1 this is a multiple-word text\n text2 another text" (the second line does not have a newline) As a result I want only two sub-expression in a line using a regex like: (\w+)\s+([^\n]+)\n The first submatch should be the first word ("text1" and "text2"), while the second submatch would be the rest of the line ("this is a multiple-word text" and "another text") In my program I use regex_search with the boost::match_continuous option, all the other regex objects are created with the default options. The first line matchs the regex expression without any problem but as the second line does not end with a "\n" it does not. I'm unable to find a good regex expression which can match the two possible "ends of line" (the \n or \0 character).. I've tried some expressions without success: 1.- First I tried to match \n || \0 using: (\w+)\s+([^\n\x00]+)([\n\x00]) but it seems the \x00 is not part of the buffer, so the second line does not match. 2.- Then I tried to use the "$" string without success (By the way, I assumed "$" would work as "\n" but it does not match the "end of line" character. When should I use??) 3.- In google I found that I should use "\z" or "\Z". I tried both, but they didn't work: The last line of the text never matches! (I suppose I need to add a new option to a regex object in order the "\z" o "\Z" strings to work) Finally I've found a workaround using the regex: (\w+)\s+([^\n]+)\n* and now it works but I would like to find a way to match the end of buffer/end of string. Any idea?? Thanks in advance, Jordi

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Problems with regex lib and Codewarrior
by Steve Folly 02 Jan '05

02 Jan '05

Hi, I'm having a problem trying to compile the regex library for Codewarrior 9.3 on the Mac, for an x86 target. There wasn't a Codewarrior project so I created my own and included the source code under libs/regex/src, I'm creating a static library. 1.31.0 and 1.32.0 have the same problem: The problem is that for a Codewarrior x86 target (running on a Mac), boost configures it's BOOST_USE_FACET macro to be the standard conforming std::use_facet. Codewarrior's use_facet takes two parameters in this case. I added the two following #defines to the C++ Preprocessor preference panel: #define BOOST_NO_STD_USE_FACET #define BOOST_HAS_TWO_ARG_USE_FACET and it compiled. Is this the right fix? Should all that boost configuration stuff have spotted this set up and configured accordingly? Thanks for any help. -- Steve.

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thread (1.32.0, vc 7.1) memory & resource leak
by Sergey Skorniakov 02 Jan '05

02 Jan '05

Hello, All! I have found that threadmon_mutex, created at line 29 in tss_hooks.cpp never destroyed. Is this the intention? Why it can not be deleted during DLL_PROCESS_DETACH? With best regards, Sergey.

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