April 2008 - Boost - lists.preview.boost.org

[Regex] A bug with #define BOOST_REGEX_MATCH_EXTRA in using char type
by sevenjay 18 Apr '08

18 Apr '08

Dear all: if you #define BOOST_REGEX_MATCH_EXTRA, using char type will crash, but using string is well. Is that a bug? My environment is Windows XP, C++ Builder 2007. I show the example below: #define BOOST_REGEX_MATCH_EXTRA #include <boost/regex.hpp> #include <iostream> using namespace std; int main() { boost::regex reg("(.*)(\\d{2})"); boost::cmatch m; const char* text = "Note that I'm 31 years old, not 32."; if(boost::regex_search(text,m, reg)) { if (m[1].matched) std::cout << "(.*) matched: " << m[1].str() << '\n'; if (m[2].matched) std::cout << "Found the age: " << m[2] << '\n'; } } It will crash..... If don't #define BOOST_REGEX_MATCH_EXTRA, it works well. And the string type works both well. Maybe this is a bug? thank you for reading.

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[functional] A new version of a selector (Boost.Select)
by Dean Michael C. Berris 18 Apr '08

18 Apr '08

Hi Everyone, Is there interest in a real simple utility which chooses either the first or second element in a pair that can be used with STL algorithms? I'm attaching it with the appropriate Boost Software License. I hope this helps! -- Dean Michael Berris Software Engineer, Friendster, Inc. <dmberris(a)friendster.com> +639287291459

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‎ [serialization]JSON Archive for Boost Serialization
by Kasun Indrasiri 18 Apr '08

18 Apr '08

Hi, If we implement the JSON archives for boost serialization, it follows the Boost serialization proprietary JSON format. So to test it with any other JSON producer/consumer it is mandatory that the other parties have to follow the format that used in Boost.serialization. Is there a way make (or a format) a format that can be globally used as the Boost.serialization JSON format. Regards, Kasun

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[ptr_container] Pointer Hash Tables
by Robert Dailey 17 Apr '08

17 Apr '08

Hey, I'm not sure if anyone has thought of this, but with the new unordered containers coming up (they've already been introduced in the first visual studio feature pack), it sure would be nice to have some new additions to ptr_container: ptr_unordered_set ptr_unordered_multiset ptr_unordered_map ptr_unordered_multimap They might need better names, but you get the basic idea. Any plans on implementing these?

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[serialization] bug in wide character strings
by Jeffrey Faust 17 Apr '08

17 Apr '08

We've discovered an issue Boost has writing and reading wide character strings (wchar_t* and std::wstrings) to non-wide character file streams (std::ifstream and std::ofstream). The issue stems from the fact that wide characters are written and read as a sequence of characters (in text_oarchive_impl.ipp and text_iarchive_impl.ipp, respectively). For text streams, an EOF character terminates the reading of a file on Windows. Some wide characters have EOF (value = 26 decimal) as one of the bytes so reading that byte causes early termination of the read. We have worked around the issue by deriving our own input and output archives from text_i|oarchive_impl<Archive> and overriding load_override() and save_override for std::wstring and wchar_t*. Our implementation just sequences through the wide characters and writes them 1 by 1 as wchar_t to the archive. This isn't very elegant and is even less readable in the file than the current implementation but does resolve the problem. I looked at both Boost 1.34.1 and 1.35 and didn't see a difference in the implementation here so I'm assuming 1.35 still has the issue. I've been working with 1.34.1. Is this a known issue? Does 1.35 solve it in some other subtle way? Is there a better way that doesn't require us to derive our own streams? If not, is there a more elegant way of implementing the reading and writing of wide characters ourselves? Thanks in advance. Jeff Faust

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Spirit2 lexer feature request
by Felipe Magno de Almeida 17 Apr '08

17 Apr '08

Hi Hartmut, I'm looking at the lexer library, and I must say I'm loving it. But there's a feature request I would like to make. Is it possible to allow paramiterization of the ID type. It is now fixed in std::size_t, and it is possibly a very good default. But how would one do to parse UTF-32 in a 32 bit machine? Also, allowing any other type (EqualComparable) would let people use string types as IDs, making it easier to log a execution, since you wouldn't have to map enum values to strings. Thanks, -- Felipe Magno de Almeida

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Signal 4 in Boost Exception tests
by Emil Dotchevski 17 Apr '08

17 Apr '08

In testing Boost Exception, I get exit code 132 (signal 4, illegal instruction) from http://www.boost.org/development/tests/trunk/developer/output/HP-UX_pa_risc…. I do not know how to troubleshoot this; any ideas? -- Emil Dotchevski Reverge Studios, Inc. http://www.revergestudios.com/reblog/index.php?n=ReCode

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Spirit2 Boost 1.35.0 and proto
by Felipe Magno de Almeida 17 Apr '08

17 Apr '08

Hi, I'm trying to use spirit2, first, I downloaded boost 1.35.0 release from https://svn.boost.org/svn/boost/branches/release Then I downloaded spirit2 from https://spirit.svn.sourceforge.net/svnroot/spirit/trunk/final Tried to use it. It gave me lots of errors, so I downloaded proto from https://svn.boost.org/svn/boost/branches/proto/v3 and replaced the boost/xpressive/proto directory. It worked, except that when compiling example 6 from the lexer, it chokes on a lot of places: template <typename Lexer> struct example6_tokens : lexer_def<Lexer> { typedef typename Lexer::token_set token_set; template <typename Self> void def (Self& self) { identifier = "[a-zA-Z_][a-zA-Z0-9_]*"; constant = "[0-9]+"; white_space = token_def<>("[ \\t\\n]+") | "\\/\\*[^*]*\\*+([^/*][^*]*\\*+)*\\/" ; self = token_def<>('(') | ')' | '{' | '}' | '=' | ';'; // This chokes with conversion loses qualifiers self.add (constant, ID_CONSTANT) // This too ("if", ID_IF) ("else", ID_ELSE) ("while", ID_WHILE) (identifier, ID_IDENTIFIER) // This too ; self("WS") = white_space; // This chokes with other different errors. } token_def<std::string> identifier; token_def<unsigned int> constant; token_set white_space; }; They give these errors: D:\development\new_boost\last_svn_spirit2\boost/fusion/container/list/cons.hpp(82) : error C2440: 'initializing' : cannot convert from 'const boost::spirit::lex::terminal_holder<T,Terminal>' to 'boost::spirit::lex::terminal_holder<T,Terminal> &' with [ T=boost::spirit::lex::token_def<> *, Terminal=boost::spirit::lex::token_def<> ] Conversion loses qualifiers D:\development\new_boost\last_svn_spirit2\boost/type_traits/is_convertible.hpp(257) : see reference to function template instantiation 'boost::fusion::cons<Car,Cdr>::cons<T,boost::fusion::nil>(const boost::fusion::cons<T,Cdr> &)' being compiled with [ Car=boost::spirit::lex::terminal_holder<boost::spirit::lex::token_def<> *,boost::spirit::lex::token_def<>> &, Cdr=boost::fusion::nil, T=const boost::spirit::lex::terminal_holder<boost::spirit::lex::token_def<> *,boost::spirit::lex::token_def<>> ] D:\development\new_boost\last_svn_spirit2\boost/type_traits/is_convertible.hpp(289) : see reference to class template instantiation 'boost::detail::is_convertible_basic_impl<From,To>' being compiled with [ From=boost::fusion::cons<boost::spirit::lex::terminal_holder<boost::spirit::lex::token_def<> *,boost::spirit::lex::token_def<>>,boost::fusion::nil> &, To=boost::fusion::cons<boost::spirit::lex::terminal_holder<boost::spirit::lex::token_def<> *,boost::spirit::lex::token_def<>> &,boost::fusion::nil> ] D:\development\new_boost\last_svn_spirit2\boost/type_traits/is_convertible.hpp(366) : see reference to class template instantiation 'boost::detail::is_convertible_impl<From,To>' being compiled with [ From=boost::fusion::cons<boost::spirit::lex::terminal_holder<boost::spirit::lex::token_def<> *,boost::spirit::lex::token_def<>>,boost::fusion::nil>, To=boost::fusion::cons<boost::spirit::lex::terminal_holder<boost::spirit::lex::token_def<> *,boost::spirit::lex::token_def<>> &,boost::fusion::nil> ] And goes on. How should I proceed? Regards, -- Felipe Magno de Almeida

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Re: [boost] [multi_index] iterator invalidation of ordered_indezes after erase?
by joaquin＠tid.es 17 Apr '08

17 Apr '08

Hi Oliver, Kowalke Oliver (QD IT PA AS) escribió: > Hello, > become iterators of an ordered_non_unique index invalidated if I call: > > iterator erase(iterator position)? > > Or are all other iterators still valid and point to the same item as before? > All iterators except those pointing to the deleted element will remain valid and pointing to whatever they were pointing before deletion. This is true of all types of indices, not only ordered ones. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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[smart_ptr] enable_shared_from_this::shared_from_this( this );
by Daniel Frey 17 Apr '08

17 Apr '08

I had yet another idea which might improve the situation for the virtual inheritance problem that my optimized implementation of enable_shared_from_this<T> has. Additionally, the solution provides another useful feature. Currently, shared_from_this() has no parameter and thus needs to either store the pointer to T* (as part of the internal weak_ptr<T>) like the 1.35.0-solution does, or it needs to use the this-pointer. The this-pointer for the class is of type enable_shared_from_this<T>*, not of type T* - this is why my improved version needs to static-cast the this-pointer, which in turn requires a non-virtual inheritance between enable_shared_from_this<T> and T. The problem can be solved by either extending or modifying the interface: When we add the following method(s): template< typename U > shared_ptr<U> shared_from_this( U* u ); template< typename U > shared_ptr<U const> shared_from_this( U const* u ); it's then possible for a method of T to call shared_from_this(this) instead of shared_from_this() to gain a shared_ptr<T>. Additionally, the interface is generally useful, as it could be called with other pointers, e.g. to sub-objects (member variables) of T. It's IMHO a nice match to the shared_ptr-constructor which takes a shared_ptr and an additional plain pointer. Peter, Frank, what do you think?

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