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Re: [boost] unicode tools and an unicode string type
by Graham 30 Mar '09

30 Mar '09

> Re: [gsoc] unicode tools and an unicode string type (Mathias Gaunard) Mathias, We are overdue a full string Unicode support library in boost. Rogier and I developed the Unicode character library that was going to underly the Unicode string libraries to provide full Unicode char, string, and iterator support [grapheme, word, paragraph iterators etc] but never had time to complete it. Any compliant Unicode text presentation system will need this and it is not possible to write a compliant Unicode text editor without it. Please have a look at the Unicode character library at: http://www.boostpro.com/vault/ Unicode_lib.zip. Good luck. Yours, Graham Barnett

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[proto] transforms && rvalue refs
by troy d. straszheim 30 Mar '09

30 Mar '09

I'm playing with proto on gcc 4.3 with c++0x enabled and trying to see if I can use rvalue refs inside callable transforms, to tell what is/isn't temporary while transforming an expression. I have a different way to do this, involving embedding the 'rvalueness' of an object in its type... yuck. Hopefully something better is out there. The use case: a = exp(exp(b)); (as below), where a and b are terminals and exp is a proto lazy function. This expression should result in only one copy of b... You'd want the inner call 'exp(b)' to see that it is being passed an lvalue, copy the value to a temp, modify and return std::move(temp). The outer call to exp() should see that an rvalue has arrived and feel free to overwrite it and return it by std::move. I think. The closest I can get is below. I thought I'd ask for a sanity-check on this before go any further... I have the feeling the check will come back negative. Thanks in advance, -t #include <boost/proto/proto.hpp> #include <boost/ref.hpp> #include <cassert> namespace bp = boost::proto; // // Tag for calls to exp() in our DSEL // struct exp_tag { friend std::ostream& operator<<(std::ostream& os, exp_tag) { return os << "exp_tag"; } }; // // The terminal. Assume this thing is very heavy. Some construtors // have assert(0) in them to verify they aren't called. // // struct array_impl { std::string name; array_impl() : name("NONAME") { } array_impl(const std::string& name_) : name(name_) { std::cout << "name=" << name << "\n"; } // // constructors // array_impl(array_impl& rhs) : name(rhs.name + "_copied") { } array_impl(const array_impl& rhs) : name(rhs.name+ "_copied") { } array_impl(array_impl&& rhs) { name.swap(rhs.name); name += "_moved"; } array_impl& operator=(array_impl&& rhs) { name.swap(rhs.name); name += "_moved"; return *this; } // // not called // array_impl& operator=(array_impl& rhs) { assert(0); // just to be sure what is and isn't getting called } array_impl& operator=(const array_impl& rhs) { assert(0); // just to be sure what is and isn't getting called } array_impl& operator=(const array_impl&& rhs) { assert(0); // just to be sure what is and isn't getting called } friend std::ostream& operator<<(std::ostream& os, const array_impl&) { return os << "array_impl"; } }; // // The transform for calls to exp. You'd like to be able to see if // this is getting called with a movable object. // struct UnaryFnCall : bp::callable { typedef array_impl result_type; template <typename Tag> result_type operator()(Tag, const array_impl& t) { std::cout << "transform a const ref\n"; array_impl tmp(t); return std::move(tmp); } template <typename Tag> result_type operator()(Tag, array_impl&& t) { // this guy doesn't get called, but I'd like him to. assert(0); // if this trips, something good happened. return std::move(t); } }; struct Grammar : bp::or_<bp::when<bp::terminal<array_impl>, bp::_value>, bp::when<bp::unary_expr<exp_tag, Grammar>, UnaryFnCall(exp_tag(), Grammar(bp::_child0))> > { }; template <typename T> struct Expression; struct Domain : bp::domain<bp::pod_generator<Expression>, Grammar> { }; template <typename Expr> struct Expression { BOOST_PROTO_EXTENDS(Expr, Expression<Expr>, Domain); }; template<class T> typename bp::result_of::make_expr< exp_tag, Domain, T& >::type exp (T&& t) { return bp::make_expr<exp_tag, Domain>(boost::ref(t)); } // // Our expression type that // struct array : public Expression<bp::terminal<array_impl>::type> { typedef array_impl impl_t; impl_t& self() { return boost::proto::value(*this); } array() { assert(0); } array(const std::string& name) { self().name = name; } array(const array&) { assert(0); } array(array&&) { assert(0); } template <typename Expr> array& operator=(Expr const& expr) { bp::display_expr(expr, std::cout); BOOST_MPL_ASSERT(( bp::matches<Expr, Grammar> )); typedef typename boost::result_of<Grammar(Expr const&)>::type result_t; result_t r = Grammar()(expr); self().operator=(std::move(r)); return *this; } }; int main(int, char**) { array a("a"), b("b"); // Here, only one copy is made a = exp(b); std::cout << "a's name:" << a.self().name << "\n\n"; // Here, two copies are made a = exp(exp(exp(b))); std::cout << "a's name:" << a.self().name << "\n"; }

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[gsoc] unicode tools and an unicode string type
by Mathias Gaunard 30 Mar '09

30 Mar '09

I plan to submit during the week my proposal for the Summer of Code about Unicode. I plan to provide: - iterator adaptors to iterate sequences of code units, code points and graphemes, and eventually more, from a sequence in UTF-8, UTF-16, UCS-2 or UTF-32/UCS-4. - miscellaneous utilities, such as categorization of code points - normalization functions - comparisons but not collations - substring search algorithms - and finally, an unicode string type I am well aware defining yet another new string type is quite controversial, but I believe this is quite useful. A dedicated type would be able to maintain certain invariants, such as maintaining a special normalization form. Also, I believe it can be possible to come up with a string design that allows easy integration with any other existing string type, such as the ones from the standard or Qt.

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[Boost] How to generate a Bernuolli number under probablity p
by Barco You 30 Mar '09

30 Mar '09

Hi, I want to randomly generate a Bernuolli number [0, 1],with probability p ~[0 1]. How to do that with boost? Thanks! -- ------------------------------- Enjoy life! Barco You

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"[gsoc] Thread scheduler support for boost"
by Indradip Ghosh 30 Mar '09

30 Mar '09

Hi Phil and Hartmut, I am following up with the earlier thread on of extending the current threadpool library present in boost. The current approach implements N:M model by internally using the pthread APIs (pthread_schedule() and its related classes). However, for high performance latency sensitive application code, we would not only like to parellize but would also like to (i) reduce load variance against the threads (ii) create asymmetric scheduling: where a set of threads are forced to run on a subset of processors (iii) prioritize the tasks amongst threads.. One that I am thinking is to create a userland scheduler through which all scheduling decisions are made. For OS specific case, the userland scheduler can be made to use features exposed by the OS such as different scheduling algos, processor affinity,... Please let me know if you think that this direction is admissible as a plausible extension for the Boost library. I am working on this and would be sending you more details on how i think on implementing this. Regards, Indradip. > Message: 4 > Date: Wed, 25 Mar 2009 07:36:12 -0500 > From: "Hartmut Kaiser" <hartmut.kaiser(a)gmail.com> > Subject: Re: [boost] "[gsoc] Thread scheduler support for boost" > To: <boost(a)lists.boost.org> > Message-ID: <49ca2540.47c1f10a.61b0.ffffdbac(a)mx.google.com> > Content-Type: text/plain; charset="us-ascii" > >> However, I thought of your suggested extension of threadpool class >> exploiting processor affinity techniques and it sounds very >> interesting as well but I guess we would run into the same portability >> issues with regard to availability of the lower level API exposing the >> hooks to be able to develop such a facility. Another issue would be to >> qualify and justify how much improvement would this type of >> parallelism enable on top of the instruction level parallelism already >> in place for all modern processors. Although, I would still like to >> find out if you have any concrete lead in mind. > > FWIW, processor affinity is supported on many operating systems, so it > shouldn't be problematic to come up with a portable implementation. > Moreover, I believe Oliver already included something like that into his > thread_pool library (see http://tinyurl.com/cqgt5u, file > boost-threadpool.v24.tar.gz). > >> I know for sure that there are those hard engineering problems in high >> performance computing domain to ensure QOS guarantees to distributed >> real-time embedded systems. They look into processor utilization >> optimizations in the face of uncertainty of computational load on the >> system. These usually require some kind of mathematical validation of >> the scheme for the system under construction. I guess that would be >> beyond the scope of the GSOC project, given the time frame. > > I'm sure that controlling processor affinity is something to consider not > only for real time applications or high end computing. With the rising > number of cores in a chip we need to be able to influence this for everyday > tasks as well. But that's only IHMO. > >> M:N type of models would also have the same portability issue as it >> requires changing kernel code as well as the userland code in thread >> library. > > You shouldn't shy away of some feature just because Boost requires portable > implementations. Most of the time this is possible to achieve, as modern > OS's have very similar functionality, just exposed using different API's. > > Regards Hartmut >

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[gsoc] A graph visualization tool proposal
by naresh shenoy 29 Mar '09

29 Mar '09

Hi, I am applying for GSoC 2009. I just wanted to gauge the interest in the community for an implementation of a Graph Visualization library. This would enable the user to "see" the graphs and possibly manipulate them a la Graphviz. The proposal could be implemented using gtk+.

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Re: [boost] [gsoc]built-in support for dictionary words
by raindog＠macrohmasheen.com 29 Mar '09

29 Mar '09

------Original Message------ From: Vicente Botet Sender: boost-bounces(a)lists.boost.org To: boost(a)lists.boost.org ReplyTo: boost(a)lists.boost.org Sent: Mar 28, 2009 9:39 AM Subject: Re: [boost] [gsoc]built-in support for dictionary words ----- Original Message ----- From: "Phil Endecott" <spam_from_boost_dev(a)chezphil.org> To: <boost(a)lists.boost.org> Sent: Saturday, March 28, 2009 1:30 PM Subject: Re: [boost] [gsoc]built-in support for dictionary words > > kannan venkat wrote: >> Hi ,I am a student applying for GSoC 2009. I had an idea of providing >> inbuilt support for English words found on the dictionary. > > There was a thread a few days ago about Bloom filters, did you see > that? Several people expressed an interest. I think that a Bloom > filter would work well for the problem you describe i.e. checking > password strength. Is this the sort of thing that you have in mind? > For substring searching things get more complicated e.g. suffix trees. > I guess there would be interest in that too, if it could be done in the > available time. As you know I would like to see Bloom Filters in Boost. It would be great if this support for dictionaries come with them. Vicente _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost Sent from my Verizon Wireless BlackBerry

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type traites - is_virtual_base
by Robert Ramey 29 Mar '09

29 Mar '09

I've noticed that this is returning true when it should be returning false in the tests on 64 bit compilers. Is it possible that 64 bit structure alignment might be breaking the implementation? tests for SUN compilers also manifest this symptom. Maybe the has a similar cause. Robert Ramey

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[gsoc] interest check for BigDecimal class
by kannan venkat 29 Mar '09

29 Mar '09

Hi, I am a student applying for GSoC 2009. I was always interested in a BigInteger class for c++ like the one provided by JAVA.i learnt that it was implemented in a previous year's GSoC. But i could not find it in the boost package i downloaded(i beg your pardon if i am wrong). Please let me know if there is scope to work on that. One more feature missing in boost is a BigDecimal class.Would it be good idea to implement the BigDecimal class with all their functionalities -overloading all arithmetic,assignement & comparison operators , functions for other basic operations. bye kannan

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[gsoc]built-in support for dictionary words
by kannan venkat 29 Mar '09

29 Mar '09

Hi ,I am a student applying for GSoC 2009. I had an idea of providing inbuilt support for English words found on the dictionary. As far as i have searched i found that there isn't support for dictionary words in boost (please correct me if i am wrong & if i am trying to reinvent the wheel). In many situations i had wanted to have a list af all meaningful english words(inclusive of places & common names of people) , specially in cryptographic applications which include deciphering ciphers & other applications related to words(like finding meaningful words in a random grid of characters) . And I could not find any in-built support for this requirement.I had to write my own algorithm to work on an external list. Thus i think it might be useful. I plan to provide *support for list of all meaningful words . *efficient methods to search if a string is a valid english word. *advanced searched options for checking if a given string is a substring is of any valid english word in an efficient manner. *methods to check if any anagram of a given string is a valid english word. could you tell me if this will be a useful contribution & give suggestions if there can be any other useful feature related to this.. bye kannan

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