August 2006 - Boost-users - lists.preview.boost.org

[regex] - Doubts of a regex beginner on boost::regex getting aborted.
by kiran 30 Aug '06

30 Aug '06

Hi, I have 2 doubts 1) Why is regex expr("Resurfacing.*?Home", boost::regex::icase) getting aborted. ? 2) How to make boost regex behave like perl regex ? I mean "dot" in boost::regex is taking new lines as well. How to prevent this ? Is "boost::regex::perl" flag the answer to the question ? Thanks in advance Kiran.

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Mismatch and regex newbie problem still problem
by david v 30 Aug '06

30 Aug '06

So to sum-up. If the regex i'm looking for is "testing" and the string to search the regex for is "tastung" (obviously this is a short example but i'm dealing with more complex regular expressions. how can i get the number of mismatches. Basically the output of the program would tell me: >2 mismatches found in string "tastung" at position 2 (a) and 5(u). I have tried the iterator above but does not seem to do what i want??? std::string::const_iterator start = in.begin(); std::string::const_iterator end = in.end(); boost::sregex_token_iterator i(start, end, *regex, -1), j; while(i != j) { cout << *i << endl; }

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timed_mutex::scoped_timed_lock
by Andrew Wingorodov 30 Aug '06

30 Aug '06

Why result of my program such? auth() sleeps one second, and I have established four in timeout. I thought, that will be "okey". why timeout? # ./a auth auth end timeout! timeout! timeout! # ///----------------------------- static timed_mutex mut; void timeout () { timed_mutex::scoped_timed_lock lk (mut,4); if ( lk.locked ()) cout << "timeout!" << endl; else cout << "okey!" << endl; } timed_mutex::scoped_timed_lock *lock; void auth () { cout << "auth" << endl; boost::thread::sleep ( delay(1)); cout << "auth end" << endl; delete lock; } int main () { lock = new timed_mutex::scoped_timed_lock (mut,10); thread_group run; run.create_thread ( &auth); run.create_thread ( &timeout); run.create_thread ( &timeout); run.create_thread ( &timeout); run.join_all(); } -- andr.ru

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reference_wrapper question
by Ovanes Markarian 29 Aug '06

29 Aug '06

Hello, I have a small problem. Some of my data holders have dereference operator which returns refernces to contained types. The problem I face here is that I have some noncopyable types and the dereference operator fails to compile. I thought using a reference_wrapper class could do the trick, but then I can not call functions on the contained type without explict casting, regardless operator T&() const defined. here is a small test app to simulate the behavior: #include <boost/ref.hpp> #include <boost/array.hpp> #include <boost/utility.hpp> using namespace std; template<class T> struct test { test() : ptr(new T()) {} ~test() { delete ptr; } boost::reference_wrapper<T> operator*() { return boost::ref(*ptr); } T* ptr; }; template<class T, int N> class array : public boost::array<T,N> , private boost::noncopyable {}; int main(int argc, char* argv[]) { test< array<int,10> > t; int size = (static_cast<array<int,10>&>(*t)).size(); } Is there any way to call the last line like: int size = (*t).size(); operator ->() would work just fine, but I need to support both. Thanks for help, Ovanes Markarian

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Build program_options using stdcall
by Ben Weatherman 29 Aug '06

29 Aug '06

I want to build the program_options library, but using the stdcall calling convention. Is there a command-line parameter I can pass to bjam that will do this? Thanks in advance, Ben

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bind trouble
by Sebastian Weber 29 Aug '06

29 Aug '06

Hello everybody! I ran into a very weird problem with boost::bind and boost::function. I am using boost 1.33.1 with a g++ 4.0.3 on a Ubuntu dapper system. The code which does not compile is: boost::function< double(double) > pFunc = boost::bind(std::pow, _1, -3); While this code fragment does: double f(double k, double p) { return std::pow(double(k), p); } boost::function< double(std::size_t) > pFunc = boost::bind(f, _1, -3); Ok, I got a solution, but may someone enlighten me what is wrong with the first version? The error message from g++ is correlFunc.cpp: In function 'int main(int, char**)': correlFunc.cpp:184: error: no matching function for call to 'bind(<unknown type>, boost::arg<1>&, double)' Thanks in advance! Greetings, Sebastian Weber

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[Regex] - Is this a limitation of sregex_iterator ?
by kiran 29 Aug '06

29 Aug '06

Hi I am using sregex_iterator to parse an html file like below. string htmlFile; //populate htmlFile with a file contents regex regExpr("Resurfacing(.|\\n)*Home", boost::regex::icase); sregex_iterator itr(htmlFile.begin(), htmlFile.end(), regExpr); But that is throwing and std::runtime_error exception with message "Regular expression too big". What can i do to avoid this ? I went through http://www.boost.org/libs/regex/doc/configuration.html and changed the variables like below #define BOOST_REGEX_NON_RECURSIVE #define BOOST_REGEX_BLOCKSIZE (4096 * 10) #define BOOST_REGEX_MAX_BLOCKS 1024 Even after that i am getting the same error message. I found that when i changed the regular expression ( i mean a simpler 'regExpr' variable) to a simpler one, the exception (std::runtime_error) was not thrown. I need to parse big html files for some complex regular expressions. I dont mind even if the sregex_iterator takes much memory or time.How can i solve this error. ? Or is this a limitatiton of boost::regex library. Thanks In Advance Kiran.

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Mismatch and regex newbie problem still problem
by david v 29 Aug '06

29 Aug '06

Yes i think there were some misunderstanding here.. I think that comes by the definition you have of mistake. A mistake for me is as follows: Regex: "testing" String_to_search: "tastung". The output should be that the regex testing was found but with 2 mismatches that are "a" and "u". So a mismatch is a letter that was not found. It may sound weird to you but the way i'm using the regex is to identify genomic regions, so in other words for biological applications. In some cases my regex is a piece of DNA such as "atgcta" and i want to search for this regex in another piece of DNA. Given the fact that the regex "atgcta" can be found in the genome many times i will get probably get a lot of matches. But in some cases i want to be able to search for "atgcta" but i want to allow some mismatches. Obviuously i will even get more matches but i think regex can be a more much efficient way that by building ip aligment matrices. ANy idea how to handle the example above >-----Original Message----- >From: boost-users-bounces_at_[hidden] [mailto:boost-users- >bounces_at_[hidden]] On Behalf Of david v >Sent: Tuesday, August 29, 2006 9:08 AM >To: boost-users_at_[hidden] >Subject: [Boost-users] Mismatch and regex newbie problem still problem > >So to sum-up. >If the regex i'm looking for is "testing" and the string to search the >regex >for is "tastung" (obviously this is a short example but i'm dealing with >more complex regular expressions. > >how can i get the number of mismatches. Basically the output of the >program >would tell me: > >2 mismatches found in string "tastung" at position 2 (a) and 5(u). [Nat] Maybe I'm completely misunderstanding you. If so, please forgive me. I think you're saying that you want to start with the regex "testing" and have the library detect that the string "tastung" is somehow similar but nonetheless distinct. My belief is that, given the regex "testing", the library will not recognize the string "tastung" in any way. It will simply report that no match was found. You could construct a more complex regex that would handle this particular example. You could, for instance, say that you want to match a "t", followed by an arbitrary character, followed by "st", followed by another arbitrary character, followed by "ng". The library would report that the string "tastung" matches that regex, and you could ask it to tell you the specific substrings matching the variable parts. But if you want to allow arbitrary variance in any character position -- as long as some other set of character positions matches -- then I'm a little perplexed as to how to express that in a regular expression. Maybe an exhaustive family of acceptable alternatives? But if you're dealing with longer expression strings, that could explode really quickly. I think you need to get really specific about the rules you want to use to detect a "mismatch." Then you need to figure out whether the regex library is the right tool to help you apply those rules. Again, sorry if I'm way off base here.

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Mismatch and regex newbie problem still problem"
by david v 29 Aug '06

29 Aug '06

Hello, As James pointed out the right place to start with will be suffix tree algorithms. The only thing i don't know if this is going to be very time consuming ??? ######For Brian.... 1) What's the longest string you're searching for? For the moment is limited to 6 to 8 characters. 2) What's the smallest bit-width of any cpu on which you're running your code? I'm on 64 dual opteron machine 3) How familiar with string searching/matching are you? Quite familiar but was looking for a cpp library that could handle it instead of trying to rewrite things. Best, david

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Re: [Boost-users] Mismatch and regex newbie problem still problem
by Nat Goodspeed 29 Aug '06

29 Aug '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of david v > Sent: Tuesday, August 29, 2006 10:02 AM > To: boost-users(a)lists.boost.org > Subject: [Boost-users] Mismatch and regex newbie problem still problem > > It may sound weird to you but the way i'm using the regex is to identify > genomic regions, so in other words for biological applications. > In some cases my regex is a piece of DNA such as "atgcta" and i want to > search for this regex in another piece of DNA. [Nat] That's not weird. I wasn't questioning your desired processing, just trying to figure out where the disconnect lies. > in some cases i want to be able to search for "atgcta" but i > want to allow some mismatches. Obviuously i will even get more matches but > i > think regex can be a more much efficient way that by building ip aligment > matrices. [Nat] This is where you have to get really specific about what kinds of mismatches you want to recognize. For example, will the sequence always begin with "at" and end with "ta" and be separated by exactly two items? ("atxxta") In that case regex is perfect for the problem. If the variable items are at fixed positions within the original pattern, it's easy. But since I don't yet know the full set of cases you intend to allow as a "mismatch," there's room for me to speculate that you might want to find "xtgcta" or "axgcta" or "atxcta" or "atgxta" or "atgcxa" or "atgctx" (one item wrong) or "xxgcta" or "xtxcta" or ... That's for a sequence length of 6. The full list of permutations is so long that you'd want to generate it programmatically. Step up to a length of 7 and that list gets alarmingly longer. That's what I meant when I said that it could quickly explode. How many items must match the original pattern before you recognize a valid "mismatch"? Presumably it's at least 1, otherwise you'd validly "mismatch" every position in every string. In practice, matching only 1 item out of 6 makes little sense to me either. You need to define what does make sense. It may be that regex is still the best tool for the job. But depending on the full set of possibilities that you mean by "mismatch," you might have to hand-code the (mis)match testing instead. I can imagine generating a regex string that would choke the library.

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