- Boost-users - lists.boost.org

Re: [Boost-users] g++ warning: comparing floating point with == or!= is unsafe
by Nat Goodspeed 30 Jul '06

30 Jul '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of David Abrahams > Sent: Saturday, July 29, 2006 5:15 PM > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] g++ warning: comparing floating point with == > or!= is unsafe > > > the warning is cause by the code: > > > > // Avoid underflow. > > if( f1 == static_cast<FPT>(0) || > > f2 > static_cast<FPT>(1) && f1 < f2 * > > (std::numeric_limits<FPT>::min)() ) > > return static_cast<FPT>(0); > > > > Could someone modify the code to allow it to compile without warnings on > > g++? > > Try replacing > > f1 == static_cast<FPT>(0) > > with > > f1 [Nat] Maybe (! f1) instead?

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boost::bind question / bug(?)
by Michael Nicolella 30 Jul '06

30 Jul '06

Having trouble compiling this code. Only tested in VC8: Removing 'const' from only the static class function seems to allow it to compile. Below is the error messages... #include <boost/bind.hpp> #include <boost/function.hpp> struct A { static void foo( const int ) { } }; void bar( const int ) { } int main() { boost::bind( &A::foo, _1 ) ; boost::bind( &bar, _1 ) ; } ------------- 1>------ Rebuild All started: Project: test_vc8, Configuration: Debug Win32 ------ 1>Deleting intermediate and output files for project 'test_vc8', configuration 'Debug|Win32' 1>Compiling... 1>main6.cpp 1>c:\projects\test_vc8\test_vc8\main6.cpp(17) : error C2665: 'boost::bind' : none of the 2 overloads could convert all the argument types 1> c:\projects\boost\boost\bind.hpp(1400): could be 'boost::_bi::bind_t<R,F,L> boost::bind<void(*)(int),boost::arg<I>>(F,A1)' 1> with 1> [ 1> R=boost::_bi::unspecified, 1> F=void (*)(int), 1> L=boost::_bi::list1<boost::arg<1>>, 1> I=1, 1> A1=boost::arg<1> 1> ] 1> c:\projects\boost\boost\bind\bind_cc.hpp(26): or 'boost::_bi::bind_t<R,F,L> boost::bind<void,int,boost::arg<I>>(R (*)(B1),A1)' 1> with 1> [ 1> R=void, 1> F=void (*)(int), 1> L=boost::_bi::list1<boost::arg<1>>, 1> I=1, 1> B1=int, 1> A1=boost::arg<1> 1> ] 1> while trying to match the argument list '(void (*)(const int), boost::arg<I>)' 1> with 1> [ 1> I=1 1> ] 1>Build log was saved at "file://c:\projects\test_vc8\test_vc8\Debug\BuildLog.htm" 1>test_vc8 - 1 error(s), 0 warning(s) ========== Rebuild All: 0 succeeded, 1 failed, 0 skipped ==========

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seeking a better way of regex replacing!
by llwaeva＠21cn.com 30 Jul '06

30 Jul '06

Hi there, boost:regex is powerful in string replacing. I am working with a complicate case which need a faster method in replacing substring. Here is my problem. I have a big string contains some pattern %K{xxx}, where xxx is a filename which may vary from place to place. e.g. BIG_STRING = ... ... %K{abc.txt} ... ... ... ... %K{foo.ini} ... ... OK, what complicated is that: I must retrieve the filename from %K{xxx}, load the content of the file and then replace %K{xxx} with the content. I search the code with a loop string::const_iterator start, end; string filename, content; boost::regex re("%K\\{(.*)\\}"); boost::match_results<std::string::const_iterator> what; boost::match_flag_type flags = boost::match_default; start = BIG_STRING.begin(); end = BIG_STRING.end(); while ( regex_search(start, end, what, re, flags) ) { if (what[1].first!=what[1].second) { filename = string(what[1].first, what[1].second); } content = LoadFile(filename); // transform the const_iterator to iterator string::iterator sbegin(BIG_STRING.begin()), send(BIG_STRING.begin()); std::advance(sbegin, distance<string::const_iterator>(sbegin, what[0].first)); std::advance(send, distance<string::const_iterator>(send, what[0].second)); // replace the content BIG_STRING.replace( sbegin, send, content ); // reset the current position of the source string to search the next pattern start = what[1].second; // I copy the code from the document of boost, don't know what the following code for flags |= boost::match_prev_avail; flags |= boost::match_not_bob; } The second approach is to retrieve the filename and load the content seperately, build the substitute format and replace all the patterns with replace_all_regex, e.g. string& escape_format( string& input ) { replace_all( input, "$", "$$" ); replace_all( input, "\\", "\\\\" ); replace_all( input, ":", "\\:" ); replace_all( input, "?", "\\?" ); replace_all( input, "(", "\$" ); replace_all( input, ")", "\$" ); return input; } stringstream reformat; string regex_text; int n=0; while ( regex_search(start, end, what, re, flags) ) { if (what[1].first!=what[1].second) { filename = string(what[1].first, what[1].second); } content = LoadFile(filename); regex_text += string(what[0].first, what[0].second); reformat << "(?" << ++n << " " << escape_format( content ) << ")"; // reset the current position of the source string to search the next pattern start = what[1].second; // I copy the code from the document of boost, don't know what the following code for flags |= boost::match_prev_avail; flags |= boost::match_not_bob; } // replace the whole string at last replace_all_regex( BIG_STRING, boost::regex(regex_text), reformat.str(), format_all ); But this approach cause exception!!! Any better idea for my problem? Thanks in advance.

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BOOST_CHECK problem!
by 袁晓辉 30 Jul '06

30 Jul '06

The doc says "It(BOOST_CHECK) also increments an error count<http://www.boost.org/libs/test/doc/components/minimal_testing/index.html>", but it seems not: #include <boost/test/included/unit_test_framework.hpp> using boost::unit_test::test_suite; void test1() { BOOST_CHECK(false); } test_suite* init_unit_test_suite( int, char* [] ) { test_suite* test= BOOST_TEST_SUITE( "Unit test ); test->add( BOOST_TEST_CASE( &test1), 1); return test; } Output: ----------------------------------------------------- Running 1 test case... xxx.cpp(171): error in "test1": check false failed *** No errors detected ----------------------------------------------------- ps. I am using boost-1_33_1.

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replace_all_regex help
by llwaeva＠21cn.com 30 Jul '06

30 Jul '06

Hi there, I wrote a piece of code to handle MIME header based on boost. The program subsitite the MIME header (from, to, subject, etc.) into a template with specific macro. Because the macro may occur everywhere in the template once or more, so I apply replace_all_regex. First of all, I need to transform the substitute string to escape special characters // input is a substitute string that will replace the macro string& escape_format( string& input ) { replace_all( input, "$", "$$" ); replace_all( input, "\\", "\\\\" ); replace_all( input, ":", "\\:" ); replace_all( input, "?", "\\?" ); replace_all( input, "(", "\$" ); replace_all( input, ")", "\$" ); return input; } There are some macros definied, some of them are listed below %s represents the subject (e.g. Re: hi philip!) %S represents the subject without prefix "Re:" (e.g hi philip!) %f represents the "form" (e.g. tom(a)hotmail.com) %t represents the "to" (e.g. philip(a)hotmail.com) ... With regex, I can replace all the macros with the help of format, something like replace_all_regex( source, boost::regex("(%f)|(%t)|(%s)|(%S)"), "(?1 xxx)(?2 yyy)(?3 aaa)(?4 bbb)", format_all ); In order to get the subject without prefix "Re:", I use erase_regex as follow string& deRe(string& input) { boost::regex regexp("^[[:space:]]*Re:[[:space:]]*"); erase_regex( input, regexp ); return input; } So simple!!! However, the order and number of macro will be changed sometimes. So I need a better way to build regex and format. I've got a function to do that // rformat is a stringstream for building a format // text is a substitute string // re_text is a string for building a regular expression // re is a string or regular expression, i.e. the macro // format_num is an global integer to hold the current number of format items (initialize to zero) void format_text(stringstream& rformat, string& text, string& re_text, const string& re) { format_num++; rformat << "(?" << format_num << " " << escape_format(text) << ")"; if (format_num>1) re_text += "|"; re_text += "(" + re + ")"; } Now, it's ready to build the regular expression and subsitiude formation dynamically. Here is an example, string regex_text; stringstream reformat; string source; // source is a string containing text and macros // spHeader is char* which is obtained from MIME parser. // if (spHeader) { format_text( reformat, string(spHeader), regex_text, "%s" ); // for %s format_text( reformat, deRe(string(spHeader)), regex_text, "%S" ); // for %S // Suppose spHeader is "Re: hi philp!", then // regex_text = "(%s)|(%S)" // reformat.str() = "(?1 Re: hi philip!)(?2 hi philip!)" replace_all_regex( source, boost::regex(regex_text), reformat.str(), format_all ); } Everything is fine except that there are some meaningless characters at the end of the output string (still source). By checking the code carefully, I found that the problem maybe caused by the format_text for %S. Hiding the second format_text solve the problem. However, just hiding the first format_text also solve the problem. It is confusing me! Someone please give me a direction. Thanks.

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[Regex]Converting from old style to new style
by John Grabner 29 Jul '06

29 Jul '06

I used to be able to write this : void LineTracker::Analyse(const std::string &Buffer) { std::string::const_iterator start, end; start = Buffer.begin(); end = Buffer.end(); boost::regex_grep(std::bind1st(std::mem_fun(&LineTracker::grep_callback), this), start, end, expression); } to get the regex to call back into my class. With the change to the new style using iterator I can do this. void LineTracker::Analyse(const std::string &Buffer) { boost::sregex_iterator m1(Buffer.begin(), Buffer.end(), expression); boost::sregex_iterator m2; std::for_each(m1, m2, *this); } However for_each makes a copy of my class, so at the end it does not update the current instance with the results. What do I need to do to have the the current instance receive the call back from regex? John.

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Re: [Boost-users] Problem with boost::multi_index
by JOAQUIN LOPEZ MU?Z 29 Jul '06

29 Jul '06

René ha escrito: > Joaquín ha escrito: > > * What happens if you fully qualify mem_fun, i.e. if > you write ::boost::multi_index::mem_fun? > > Well, when I tried this option it worked! > > It looks like gcc missed the "using boost::multi_index" > declaration. > > In order to gain experience: If you have any idea what > was the problem it will be appreciated. Not really :( Maybe the compiler gets confused by the presence of the template function std::mem_fun (does your "Item.h" explicitly or implicitly include <functional>?), but this is only a wild guess. In any case, this is a compiler bug, likely to solve if you upgrade your GCC copy. Sorry I can't give a more conclusive answer. > Thanks again. > > René Good luck with your project, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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[mpl] Collapsing sequences of integer constants
by Eric Lemings 29 Jul '06

29 Jul '06

Greetings, I'm trying to come up with an algorithm that will "collapse" a sequence of integer constants by adding like elements together. For example, typedef vector_c< int, 1,1,1,3,5,5,7,10,10 > input; would become: typedef vector_c< int, 3, 3, 10, 7, 20 > result; You can assume the sequence is already sorted. Would appreciate any tips. Thanks, Eric.

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Re: [Boost-users] Problem with boost::multi_index
by JOAQUIN LOPEZ MU?Z 28 Jul '06

28 Jul '06

Rene Tarantino wrote: > Hi : > > I'm just starting to use boost utility library and it > seems very promising. I am trying to define a new > multi_index type and gcc it's giving me error messages. > > First I properly added the includes for boost::multi_index : > > #include <boost/multi_index_container.hpp> > #include <boost/multi_index/mem_fun.hpp> > #include <boost/multi_index/hashed_index.hpp> > > then the includes for "Item" and "ObjectId" declarations: > > #include "Item.h" > > following that appears this: > > typedef multi_index_container< > Item*, > indexed_by< > hashed_unique<mem_fun<Item, ObjectId, &Item::getId> > > > > > ItemsContainer; > > When I try to compile this code gcc reports the following errors: > > error: 'mem_fun' was not declared in this scope > error: template argument 1 is invalid > error: type/value mismatch at argument 3 in template parameter > list for 'template<class Arg1, class Arg2, class Arg3, class Arg4> > struct boost::multi_index::hashed_unique' > error: expected a type, got '&emedia::lumiere::Item::getId' > error: template argument 1 is invalid > error: template argument 2 is invalid > error: expected unqualified-id before '>' token > > It seems that I'm forgetting something. It's very strange because > all ready compilled this code in another project but I can't find > any difference with this one. Hello René, I really can't reproduce the problem you describe. The attached file tries to mimic your scenario (with a dummy Item definition) and here everything works OK. Could you please try it in your environment? I guess the problem is not in what you describe, but in what you don't, I mean, sorrounding details that you're taking for granted. Things to check: * Are you using some using directive? Which one? * Are you doing some funny thing with the "mem_fun" identifier inside "Item.h"? * What happens if you fully qualify mem_fun, i.e. if you write ::boost::multi_index::mem_fun? I hope some of the above rings a bell for you. Please report back. Best, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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Problem with boost::multi_index
by Rene Tarantino 28 Jul '06

28 Jul '06

Hi : I'm just starting to use boost utility library and it seems very promising. I am trying to define a new multi_index type and gcc it's giving me error messages. First I properly added the includes for boost::multi_index : #include <boost/multi_index_container.hpp> #include <boost/multi_index/mem_fun.hpp> #include <boost/multi_index/hashed_index.hpp> then the includes for "Item" and "ObjectId" declarations: #include "Item.h" following that appears this: typedef multi_index_container< Item*, indexed_by< hashed_unique<mem_fun<Item, ObjectId, &Item::getId> > > > ItemsContainer; When I try to compile this code gcc reports the following errors: error: 'mem_fun' was not declared in this scope error: template argument 1 is invalid error: type/value mismatch at argument 3 in template parameter list for 'template<class Arg1, class Arg2, class Arg3, class Arg4> struct boost::multi_index::hashed_unique' error: expected a type, got '&emedia::lumiere::Item::getId' error: template argument 1 is invalid error: template argument 2 is invalid error: expected unqualified-id before '>' token It seems that I'm forgetting something. It's very strange because I all ready compilled this code in another project but I can't find any difference with this one. Any idea. Thanks in advance. René

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