- Boost - lists.preview.boost.org

[Bind] Function arithmetic (sample impl inside)
by ivan.lelann＠free.fr 12 Apr '10

12 Apr '10

Hi, It's my first message here, so please excuse possible mistakes. I found that Boost.Bind offers logical operators but no arithmetical operators. Looking into boost/bind/bind.hpp, and using "logical_not" impl, I wrote the following naive patch against version 1.40. It is certainly not as robust as Boost exspects, it is quickly tested, but it seems to do the job, as you can see in the test. Please use attached documents as you see fit. Regards, Ivan. PS: attached main.cpp is compiled with g++ 4.4.1, -std=c++0x, "my" bind.hpp in same directory, and boost 1.40 in include path.

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Re: [boost] Crypto Proposal
by Chad Seibert 12 Apr '10

12 Apr '10

> Hi, > > Perhaps this link will work: > > http://socghop.appspot.com/gsoc/student_proposal/show/google/gsoc2010/chads… > Yep, it worked, thanks. > Thanks to all who gave advice, please ask if you have any questions! > It all sounds very good. Can you give an example of what porting some > Botan functionality would look like? Would it be as simple as replacing > the namespace Botan with boost::crypto/whatever in the source code? > An example of what one of the Botan tutorial examples would look like in > the new world would be nice. > Honestly, I think there is no point if you can't commit to part 2. > However, splitting it up into GSoC/non-GSoC is smart on your part. How > do you plan to commit to part 2? > Thanks and good luck :) Here's an example of boostified code, from one of the examples on the site. It's not too different from the original code (it's just commented out); this is because I don't want it to be a chore to port from Botan to Boost.Botan. Also, it is intuitively designed and I see no reason to change it. Of course, if it needs redesigning, we can discuss that afterwards. Also, there are at least 600 files to move that total 2 mb's of source, so it'll take a while, even if it is just changing namespaces and the like. But I'll get started on part 2 if part 1 finishes early. As for committing to part 2, I have some (rough) guidelines for the work to be done afterwards. I'm also taking a lighter courseload so I can spend more time working. I don't know how else to convince you. Anyways, thank you for considering my proposal! Chad Seibert #include <boost/botan.h> #include <iostream> #include <memory> int main(int argc, char* argv[]) { if(argc != 5) { std::cout << "Usage: " << argv[0] << " <passphrase> " << "<ca cert> <ca key> <pkcs10>" << std::endl; return 1; } try { const std::string arg_passphrase = argv[1]; const std::string arg_ca_cert = argv[2]; const std::string arg_ca_key = argv[3]; const std::string arg_req_file = argv[4]; //AutoSeeded_RNG rng; boost::botan::rng::auto_seeded rng; //X509_Certificate ca_cert(arg_ca_cert); boost::botan::x509::certificate ca_cert(arg_ca_cert); //std::auto_ptr<PKCS8_PrivateKey> privkey(PKCS8::load_key(arg_ca_key, rng, arg_passphrase)); std::auto_ptr<boost::botan::pkcs8::private_key> privkey(pkcs8::load_key(arg_ca_key, rng, arg_passphrase)); //X509_CA ca(ca_cert, *privkey); boost::botan::x509::ca ca(ca_cert, *privkey); // got a request //PKCS10_Request req(arg_req_file); boost::botan::pkcs10::request req(arg_req_file); // you would insert checks here, and perhaps modify the request // (this example should be extended to show how) // now sign the request //X509_Time start_time(system_time()); //X509_Time end_time(system_time() + 365 * 60 * 60 * 24); //X509_Certificate new_cert = ca.sign_request(req, rng,start_time, end_time); boost::botan::x509::time start_time(system_time()); boost::botan::x509::time end_time(system_time() + 365*60*60*24); boost::botan::x509::certificate new_cert = ca.sign_request(req, rng, start_time, end_time); // send the new cert back to the requestor //std::cout << new_cert.PEM_encode(); std::cout << new_cert.pem_encode(); } catch(std::exception& e) { std::cout << e.what() << std::endl; return 1; } return 0; } _________________________________________________________________ The New Busy is not the too busy. Combine all your e-mail accounts with Hotmail. http://www.windowslive.com/campaign/thenewbusy?tile=multiaccount&ocid=PID28…

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[preprocessor] BOOST_PP_IS_UNARY()
by Lorenzo Caminiti 11 Apr '10

11 Apr '10

Hello all, Do you know what are the drawbacks of using BOOST_PP_IS_UNARY()? If you have used it, what is your experience with its portability? BOOST_PP_IS_UNARY() is *not* part of the Boost.Preprocessor public API as it is #defined in boost/preprocessor/detail/is_unary.hpp. However, Boost.Preprocessor, Boost.Typeof, and Boost.Spirit seem to use BOOST_PP_IS_UNARY() at least internally: $ find /usr/include/boost/ -name "*.[hc]pp" -exec grep -Hn "BOOST_PP_IS_UNARY" {} \; /usr/include/boost/preprocessor/facilities/apply.hpp:24:# define BOOST_PP_APPLY_I(x) BOOST_PP_EXPR_IIF(BOOST_PP_IS_UNARY(x), BOOST_PP_TUPLE_REM_1 x) /usr/include/boost/typeof/template_encoding.hpp:61: BOOST_PP_IS_UNARY(x),\ /usr/include/boost/spirit/utility/rule_parser.hpp:826: BOOST_PP_EXPR_IIF(BOOST_PP_COMPL(BOOST_PP_IS_UNARY(elem)),elem) In addition, Paul Mensonides mentioned the following in http://lists.boost.org/Archives/boost/2004/08/70238.php > Paul Mensonides wrote: > I know. They (and other types of detection macros) are very useful. Right now, > the Borland configuration is used by the IBM preprocessor and the Sun > preprocessor also. I'd like to know whether or not those macro definitions work > correctly on those preprocessors before I add it. Though those macros aren't > part of the public interface, they are part of the internal interface. I.e. > they are used internally as if they were a public interface (though they are > used carefully on some preprocessors). They are stable, and the worst thing > that might happen in the future is that they will be moved to a different > directory. Thus, you can use them, but beware of VC and versions of MWCW prior > to v9. They in particular have severe problems with expansion order. E.g. VC > will even fail this test: My Boost.Contract code internally uses BOOST_PP_IS_UNARY() and it works fine on GCC 4.2.4 (Ubuntu Linux), MSVC 8.0 (Windows XP), and GCC 3.4.4 (Cygwin) but I have not tried other compilers (including Borland's). Thank you. Lorenzo

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[Locale] Static locale initialisation
by Alexander Lamaison 11 Apr '10

11 Apr '10

I'm encountering a crash with Boost.Locale as the process terminates I initialise the global Boost.Locale in the contructor of a class with a single static instance (the ATL module to be exact) as I don't have access to the code of my main method (it comes from the Boost.Test runner). A static object seems to be the only logical place to put this code: #include <boost/locale.hpp> // boost::locale::generator class CModule : public ATL::CAtlModule { public : CModule() : ATL::CAtlModule() { try { // Initialise Boost.Locale translation mechanism generator gen; gen.add_messages_path("C:/My/Path"); gen.add_messages_domain("swish"); std::locale::global(gen("")); // default locale } catch (std::exception) {} } HRESULT AddCommonRGSReplacements(IRegistrarBase*) { return S_OK; } }; CModule _AtlModule; // Global module instance However, when I run my EXE, it crashes as it terminates with: Unhandled exception at 0x5ba43d93 (msvcp80d.dll) in test-shell_folder.exe: 0xC0000005: Access violation reading location 0x0321f4e4. and the following stack trace: msvcp80d.dll!std::_DebugHeapDelete<std::locale::facet>(std::locale::facet * _Ptr=0x023af590) msvcp80d.dll!_Deletegloballocale(void * ptr=0x5bb25258) msvcp80d.dll!tidy_global() msvcp80d.dll!_Init_atexit::~_Init_atexit() msvcp80d.dll!`dynamic atexit destructor for 'init_atexit''() msvcp80d.dll!_CRT_INIT(void * hDllHandle=0x5ba30000, unsigned long dwReason=0x00000000, void * lpreserved=0x00000001) msvcp80d.dll!__DllMainCRTStartup(void * hDllHandle=0x5ba30000, unsigned long dwReason=0x00000000, void * lpreserved=0x00000001) msvcp80d.dll!_DllMainCRTStartup(void * hDllHandle=0x5ba30000, unsigned long dwReason=0x00000000, void * lpreserved=0x00000001) ntdll.dll!_LdrpCallInitRoutine@16() ntdll.dll!_LdrShutdownProcess@0() ntdll.dll!_RtlExitUserProcess@4() kernel32.dll!76843b69() msvcr80d.dll!__crtExitProcess(int status=0x00000000) msvcr80d.dll!doexit(int code=0x00000000, int quick=0x00000000, int retcaller=0x00000000) msvcr80d.dll!exit(int code=0x00000000) test-shell_folder.exe!__tmainCRTStartup() test-shell_folder.exe!mainCRTStartup() If I move the initialisation code to run just before each point I need to use translate() then it works fine. So maybe this has something to do with the way static data is destroyed. This is on Windows - not sure about other platforms. Any ideas? Many thanks. Alex Lamaison P.S. I realise Boost.Locale isn't in Boost yet but previous discussions have been here so it seems a reasonable place to ask.

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Re: [boost] [GSoC]Bits and Ints
by shiyang yang 10 Apr '10

10 Apr '10

Hi Thanks for the help. But I am still not very sure about the meaning of dynamic_bitfields. Does it mean the size of the bitfield is dynamic? Shiyang

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[GSoC]Bits and Ints
by shiyang yang 10 Apr '10

10 Apr '10

Hi I have been working on the proposal of this project, but still have some questions, could anyone please give me some help? For the bits part, what does the 'compressed' mean, what is the main difference between the array, vector and the normal ones? Is there any other existing integral special functions that mentioned in the second part? Where can I find them? Thanks a lot Shiyang Yang

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Re: [boost] Boost.Botan final proposal
by Chad Seibert 10 Apr '10

10 Apr '10

Hi, Perhaps this link will work: http://socghop.appspot.com/gsoc/student_proposal/show/google/gsoc2010/chads… Thanks to all who gave advice, please ask if you have any questions! Chad Seibert _________________________________________________________________ The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with Hotmail. http://www.windowslive.com/campaign/thenewbusy?tile=multicalendar&ocid=PID2…

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Message Hashing Interface (SHA-1/256/384/512, MD4/5)
by Scott McMurray 10 Apr '10

10 Apr '10

I wrote up some SHA message hashers recently, which came out rather nicely using templates to handle the commonalities between SHA-1/256/384/512. The one issue that came up is how to handle retrieving the hash from the accumulator. When working with just the raw SHA compressor it's not a problem, but when hashing messages, getting the hash of the message requires appending padding and a length. That means that SHA and MD[45] hashing cannot use the same simple interface of Boost.CRC that, in essence, consists of calling process_byte() and inspecting the cheap, const member function hash() as needed. Here are a couple of options: 1) The hash() function is non-const, and it appends the passing and length, calculates the hash, and resets the accumulator to be ready for the next message. This is perhaps the most efficient interface. 2) The hash() function is const, and copies the accumulator, then pads and length-appends the copied version, getting the hash from there instead. That gives perhaps the nicest interface, but the extra copying would be somewhat expensive. That said, it's overhead per message, not dependant on the length of the message, so it may be acceptable. Also, the hash function would still be quite expensive, contrary to usual expectations for const member functions. 3) The hash() function is just a cheap const that returns the current state of the compressor. This would require an additional end_of_message() function that would apply the padding and probably things up such that the next process_byte function would start a new message by resetting the compressor. That would allow the hash() function to be cheaply called as many times as desired between calling end_of_message() and providing the data for the next message. One big problem with this one is that hash() can be called after providing data but before calling end_of_message(), at which point is return value is essentially useless. I think I like (1) best, because it allows the user to copy it and get (2) if they'd rather, and doesn't have the potential call sequencing problem of (3). Any opinions, suggestions, alternatives, or comments? ~ Scott McMurray P.S. Yes, the point here is to create Boost.MD and Boost.SHA libraries. The first client would be Boost.UUID to allow it to offer the MD5 name-based UUIDs it currently cannot. It needs a hashing concept so that it can parametrise name_generator similarly to how it currently parametrises basic_random_generator [1]. [1] http://www.boost.org/doc/libs/1_42_0/libs/uuid/uuid.html#Random%20Generator

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Log/tropical semiring for boost math
by Alex Graves 10 Apr '10

10 Apr '10

Hi, I work in machine learning, and often need to do probability computations in the log scale to avoid underflows. A nice way to do this is to use a class where the add, divide etc. operators are overloaded by their log scale equivalents (e.g. log(a*b) = log(a) + log(b)). In other words a class implementing the log semiring <http://en.wikipedia.org/wiki/Semiring>. Also useful in this context is the tropical semiring, where adding is replaced by taking the maximum (or minimum) of the arguments. I looked for these in the boost math library, but couldn't find anything. So I wrote my own. Did I miss something? And if not, is anyone interested in adding my implementation to boost math? Alex

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Phoenix.bind VS Lambda.bind
by Alexey Tkachenko 10 Apr '10

10 Apr '10

Hi, Now I'm looking at Phoenix and Lambda libraries. Could somebody explain why Lambda allows to use the following expression: void foo(int) { ... } ... bind(foo, _1)(10); yet Phoenix does not. Phoenix requires to use helper variable: void foo(int) { ... } ... int i = 0; bind(foo, _1)(i); I've read document about "Forwarding Function Problem" (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2002/n1385.htm) I understand the core issue, but how does Lambda.bind solve it? Thank you, Alexey.

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[serialization][1_42_0] basic_binary_oarchive - warning: comparison is always true due to limited range of data type
by Jeff Flinn 09 Apr '10

09 Apr '10

basic_binary_oarchive.hpp has this member: void save_override(const class_id_type & t, int){ // upto 32K classes assert(t.t <= boost::integer_traits<boost::int_least16_t>::const_max); const boost::int_least16_t x = static_cast<const boost::int_least16_t>(t.t); * this->This() << x; } It doesn't seem that there is a need for this runtime assert at all given the definition: BOOST_ARCHIVE_STRONG_TYPEDEF(int_least16_t, class_id_type) Can't the assert be removed to quiet the gcc warning? Jeff

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[utility/value_init] boost::value_initialized<T> direct-initialized?
by Niels Dekker - address until 2010-10-10 09 Apr '10

09 Apr '10

Can anybody please have a look at the following feature request by Edward Diener? https://svn.boost.org/trac/boost/ticket/3472 He proposed to add an explicit constructor, value_initialized(T const&), to boost::value_initialized<T>. This constructor would copy the value of its argument to the object held by value_initialized<T>. When such a constructor would be added, an object held by value_initialized<T> might no longer be value-initialized. Instead it might be direct-initialized. Does anybody have any moral (?) objections against the idea that value_initialized<T> might hold a non-value-initialized object? Personally I think it would be useful to allow the wrapped object to be direct-initialized. But I do think there's a small risk that the new explicit constructor might cause ambiguities in legacy user code. Therefor I suggested adding an extra "tag" parameter to the new constructor, of a new type, boost::direct_initialized_t: struct direct_initialized_t { }; value_initialized(T const&, direct_initialized_t) Does anyone else also think that's a good idea? Or does anyone prefer the explicit value_initialized(T const&) constructor originally proposed by Edward? See also the thread starting at: "Re: [boost] Transfer of Maintenance Rights (utility/value_init)" http://lists.boost.org/Archives/boost/2010/03/164125.php Kind regards, Niels -- Niels Dekker http://www.xs4all.nl/~nd/dekkerware Scientific programmer at LKEB, Leiden University Medical Center

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xml?
by Maarten L. Hekkelman 09 Apr '10

09 Apr '10

Hi, I saw there was some discussion on this list regarding an XML library. I wrote a C++ based XML library recently as part of the work I do on e.g. MRS, a full-text retrieval system for biological databanks. (See http://mrs.cmbi.ru.nl/ ) I extracted the XML and SOAP code from the MRS project and wrapped it into a new library. This library is called libzeep and I've put the code on Berlios (http://libzeep.berlios.de/) License is Boost. The library currently consists of: - a SAX parser with validation support based on DTD. - a simple XML library for nodes, elements, etc. - an XML writing utility/wrapper. - an xpath implementation And then the code contains a full high-performance SOAP server implementation. This code generated all SOAP related code and WSDL generator code based on the signature of exported server methods. No need to run a separate code generating tool. Network code is based on asio and I've implemented an optional pre-forked mode of operation. A previous version of libzeep is in production use for over a year now and I recently added the parser and xpath stuff to be able to drop libxml2 from the requirements for MRS. Code comes with quite a few test sets. Documentation is not updated yet for the parser and xpath but there is some for the SOAP part. I need to do a bit more testing before I can release a new version. My question now is, would this library be of interest to Boost? Perhaps it can be used, or parts of it can be recycled. And if there is interest, I'm sure there must be suggestions for improvement. You can browse the code at https://svn.cmbi.ru.nl/libzeep/trunk/ (There's also a copy at Berlios, but that may be out-of-date) The application zeep-test is a simple SOAP server, in ./tests/ you can find two simple test drivers, one for the parser and one for xpaths. Best regards, -maarten hekkelman

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[GSoC] Students; Please note..
by Rene Rivera 09 Apr '10

09 Apr '10

GSoC students, Now that the GSoC submission deadline has passed it is vitally important that you pay attention to your proposals and the comments the mentors add to them. Please address questions and suggestions we put on the comments ASAP. As it will both make our lives easier, and hence more likely to make accurate assesments of proposals. And it will increase the chances that we consider your proposals serious enough to want to move forward, if we get our feedback resolved. Good luck to all :-) -- -- Grafik - Don't Assume Anything -- Redshift Software, Inc. - http://redshift-software.com -- rrivera/acm.org (msn) - grafik/redshift-software.com -- 102708583/icq - grafikrobot/aim,yahoo,skype,efnet,gmail

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[config] New defect macro: BOOST_NO_COMPLETE_VALUE_INITIALIZATION
by Niels Dekker - address until 2010-10-10 09 Apr '10

09 Apr '10

FYI, John Maddock has just added the tests to trunk/libs/config that I wrote for a new defect macro: BOOST_NO_COMPLETE_VALUE_INITIALIZATION https://svn.boost.org/trac/boost/changeset/61153 And some documentation: https://svn.boost.org/trac/boost/changeset/61154 A test failure indicates that the specific compiler doesn't have completely implemented value-initialization. In the coming few days, the test is likely to cause regression failures, because I still need to define the defect macro for those specific compilers (at boost/config/compiler). Although I already expect certain compilers to fail (MSVC <= 2010, CodeGear/Borland <= 2010, GCC < 4.4, and various versions of Sun) I chose not to define the defect macro /beforehand/, because the test output provides some extra information about the particular compiler issue. Moreover, once the defect macro is defined, the test framework no longer indicates whether the compiler defect is really there. I'll keep an eye on the regression page, http://www.boost.org/development/tests/trunk/developer/config_.html and fix them one by one, but please don't hesitate to remind me if there's a regression failure regarding the new defect macro that I overlooked. The defect macro will allow fixing ticket #3869, "Unconditional call to memset in value_initialized()", reported by Aleksey Gurtovoy: https://svn.boost.org/trac/boost/ticket/3869 by adding an #ifdef to utility/value_init.hpp: #ifdef BOOST_NO_COMPLETE_VALUE_INITIALIZATION std::memset(&x, 0, sizeof(x)); #endif Kind regards, Niels -- Niels Dekker http://www.xs4all.nl/~nd/dekkerware Scientific programmer at LKEB, Leiden University Medical Center

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Re: [boost] [msm] new version available
by Christophe Henry 09 Apr '10

09 Apr '10

> The new package on Vault is missing boost/msm/back/default_compile_policy.hpp. > Everything seems to compile fine once I grabbed it from the sandbox, so I assume > the other files in the package are the proper versions. I found the problem. SVN refuses to correctly update the directory I used to build the zip. Even cleanup has no effect, so I will delete the whole stuff and checkout again. There are actually 2 important files missing, so I had no other choice than to upload the correct version again. For all who downloaded from the vault, sorry about it, you will need to download again (the sandbox is ok though). > Also, I very much dislike that metafunctions.hpp does 'namespace mpl = > boost::mpl;' in global scope. Isn't putting anything in global scope against the > boost guidelines? Even if not, I find it quite inappropriate to inject another > library's namespace into global scope. This line is not even needed as all mpl types are qualified inside the library with ::boost::mpl so I just removed the line. This problem is there since at least the 1.20 and went unnoticed. Sadly, some of the tutorials fail to fully qualify the mpl types, so I updated them too. Both versions, sandbox and vault should now be up to date and with these 2 problems solved. Thanks, Christophe

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GSoC 2010: Heaps and Queues
by Dan Larkin 09 Apr '10

09 Apr '10

I'm another potential student throwing my hat in the ring for the heap project. I'll save most of my personal details for my proposal, but for right now I thought I'd try to get a bit of a dialogue going with the community to help me understand what it is you guys are looking for and what it is I can work towards. So I'll start with my current understanding of the situation. The way I see it, the current heap implementations in boost/pending are rather fractured. They just have simple push/pop interfaces with no mutability (well, there's mutable_heap.hpp, but that's separate and not fleshed out). All in all, what seems to be needed is a standardized heap concept/API along with a few fully-implemented models. Standard heap functionality begs the following functions: - findMin - deleteMin - insert - changeKey - merge These can all be implemented quite efficiently (either worst case or amortized O(logn) time or better) for any heap model. I would be looking to implement the d-ary, binomial, and Fibonacci heaps for sure, with relaxed and Brodal heaps as a possibility, should time allow it. These heap models would be built as extensions of a base Heap class, which could be easily wrapped in a PriorityQueue class which takes the heap-type as a construction parameter (and defaults to a d-ary heap for instance). I know that a stable priority queue was mentioned in earlier discussion, but I'm not sure what to do about that just yet. It'll take a little more thinking before I could say whether I think it'd fall under the scope of the summer project, or if it should be put on the back-burner for later addition to the library. I guess that's basically how I see the problem so far. Please let me know what you think, or what other sort of information/planning/etc. you would like to hear from me prior to my proposal/draft. Dan Larkin

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Boost.Botan final proposal
by Chad Seibert 09 Apr '10

09 Apr '10

Hi, Pending any other revisions, here's my final proposal: http://socghop.appspot.com/gsoc/student_proposal/edit/google/gsoc2010/chads… Thanks to all who gave advice, please ask if you have any questions! Chad Seibert _________________________________________________________________ Hotmail is redefining busy with tools for the New Busy. Get more from your inbox. http://www.windowslive.com/campaign/thenewbusy?ocid=PID28326::T:WLMTAGL:ON:…

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[GSoC] Bits & Ints proposal
by Murilo Adriano Vasconcelos 09 Apr '10

09 Apr '10

Here is my proposal for Bits & Ints idea: http://socghop.appspot.com/gsoc/student_proposal/show/google/gsoc2010/muril… Any comments? -- Murilo Adriano Vasconcelos

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boost::interprocess
by Rohit Goel 09 Apr '10

09 Apr '10

Hi, How can I synchronize mutlipe read/single write on a file available on a shared folder ? The multiple read/write need to be synchronized b/w different processes running on different machine. -Rohit

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[msm] new version available
by Christophe Henry 09 Apr '10

09 Apr '10

Hi all, I just finished the newest MSM version. Unfortunately, I'm afraid I'm a bit late to get it shipped with boost v1.43 but at least it will give us time to have a look at it. What is new: - the doc was rewritten almost from the ground up. - internal transitions: for all front-ends, and both ways: either in the transition table or inside state's internal transition tables - more row types (yes, even more) allowing actions to be defined in state machines or in states The last 2 points aim at making states more useful - some performance gain - new eUML syntax to get rid of parens and to better support attributes - policy for better compile-time at cost of dispatch speed. And a few minor improvements. It was not possible to implement every wish and excellent idea offered during the review at this point, but they are in no way forgotten and I do not intend to stop development now. I'm interested in any comments, especially about the doc, which, like everything new, probably is not perfect but I hope, still an improvement. You can find the new version, like always: - in the Vault (http://www.boostpro.com/vault/index.php?directory=Msm) - in the sandbox (http://svn.boost.org/svn/boost/sandbox/msm/) Regards, Christophe

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GSoC Generic Sweep Algorithm
by Sweta Yamini 09 Apr '10

09 Apr '10

Hi, I am writing my proposal for GSoC and I'm interested in writing a generic sweep algorithm. I want to write a generic algorithm which takes in functions to determine the priority of the elements to be considered in the sweep line, and a function to perform necessary computations at each such point. And supplement it with inbuilt functions for line sweep, angular sweep about a point for 2 dimensions and plane sweep for 3 dimensions. Also, implement some algorithms like Voronoi diagrams, Delaunay triangulations, visibility problems using the generic sweep algorithm. I have looked through the documentation and could not find anything related to this. Is there something I have missed? Also, could I contact anyone to discuss? Sweta Yamini Fourth Year Student Department of Computer Science And Engineering Indian Institute of Technology, Kharagpur

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[GSoC] Some new ideas for this year's GSoC
by Stefan 09 Apr '10

09 Apr '10

Hello, I am Stefan and this is my first year at GSoC as it's the first time I'm eligible to participate as a student. Since I have been using C++ and the Boost libraries for quite some time, I would be thrilled to be able to code for Boost. I have quite a few ideas, and I was wondering which ones you consider to benefit the most, therefore I'm awaiting for your feedback. Also, please let me know if any of these ideas are already implemented in any of the libraries. Here we go: * Selection algorithm (find the kth smallest element in a container, O(n) worst-case, very easy to implement) * Optimize Boost String Algorithm finders to use an efficient substring matching algorithm as opposed to the naive algorithm. Most likely because of the fact that boost has implemented the finders for strings as generic algorithms, they haven't used efficient algorithms such as KMP, Boyer-Moore, Rabin-Karp etc. \see boost/algorithm/string/detail/finder.hpp The idea is to implement efficient algorithms such as the ones mentioned above to replace the current naive implementation. Note: it may be difficult to find nth matching substring position using some of these algorithms. Difficulty: easy-medium * Implement a string algorithm for generating the suffix array. The suffix array, after being precomputed on a certain string, allows for very efficient substring searches in the future. This is useful when the string doesn't change too often but there are plenty of substring to search against. * Yet another efficient associative data structure, skip lists? * Space partitioning data structures? kd-trees? quadtrees? octtrees? collision detectors? closest neighbors? * A parser capable of evaluating mathematical expressions which contains operands,operators,function calls,variable names and constant names (also considering priority of operators): 1. a list of valid operators described by: a) number of operands (unary/binary/ternary?); b) allowed operand types; c) the precedence (priority of the operator) 2. a list of existent functions described by: a) function name; b) number of parameters; c) type of each parameter and return type; d) a callback (maybe just automatically deduce type based on the callback's type if possible) 3. a list of constants 4. a list of allowed variable names and types Here's a pseudo-C++ code sample on how it should look like: namespace m = boost::math_expressions_parser; m::parser p; p.add_operators() ('+', 1, ret<int32_t>(_1+_2)) // binary +, precedence 1 ('*', 2, ret<int32_t>(_1*_2)) // binary -, precedence 2 ('+', 3, ret<int32_t>(_1)) // unary +, precedence 3 ('-', 3, ret<int32_t>(-_1)); // unary - (also a funny face), precedence 3 p.add_functions() ("sin", ret<int32_t>(sin(_1))); p.add_constants() ("PI", 3); p.add_allowed_variables() (allowed_var<int32_t>("x")); m::expression E("1 + 3*sin(PI*x)", p); // evaluates mathematical expression E against parser p if (!E.valid()) { /* ... */ } else { std::cout << E.evaluate( ("x", 3) ); // evaluate this expression by letting x=3 E.let() ("x",4); std::cout << E.evaluate(); } //Maybe an optimization so only the parts that depend on the changed variable will be recalculated every time?. E.g.: for expression f(x)+y, f(x) is recomputed only when x is changed. This may cause problems for functions that do not always yield the same results for the same input. Maybe make this optimization optional, only if the user marks the function/operator as "volatile" or something Difficulty: hard-very hard * Someone suggested on this ml earlier that a crypto suite would be useful for boost. Maybe, but it would take a lot of time and dedication to implement. I believe that we should at least add some Cryptographic hash functions (such as md5, sha1, sha256 etc.). No one wants to install Crypto++ or something similar just to be able to compute the SHA1 sum of a file. It is a common necessity to want to compute a hash function of a string. Difficulty: very easy if you copy the implementation and just create a boost-ish interface * In-place radix sort? Radix sort is a very efficient algorithm which performs better than std::sort (my implementation) (also asymptotically better) for some particular types such as: uint8_t, uint16_t, uint32_t, unsigned char, unsigned char[2], unsigned char[4] etc. Radix sorting takes linear time, but unfortunately, linear memory. It is very useful for sorting very large amounts of numbers tho (or genetic codes and maybe some other stuff). I am able to implement some of these stuff and I'm waiting for your opinion in what would be most useful to be part of boost. Let me know if you believe that none will have any use. Yours sincerely, Stefan

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[GSoC] - Graph.boost - Graph Connectives
by Davi Barbosa 09 Apr '10

09 Apr '10

Hi, I am interested in participation in GSoC 2010 in Boost.Graph. I liked the first two options, but between these two I am much more interested in the second (graph connectives) because it seems more useful and challenging. Unfortunately, I will be having classes until the end of June (some of them will end early), so I will have a restricted time at the beginning. Of course I am explaining this in my proposal and making the schedule work with this big restriction. Do you think this could be a big problem? I am having exams right now so I did not had the time to join the list, get in contact, etc. I already started writing a proposal, but I still have one exam in a 4 hours and only after that I will be able to really write it. After finishing a draft, I would like to know if I can send it in pvt to someone for a quick review. Is anyone able to do this big favor? I had some other questions, but I already asked them in the IRC channel (with the nick "recife"). Thanks for everyone who answered! Davi Barbosa.

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[GSoC] Graph layout algorithms - proposal draft
by Milos Djuric 08 Apr '10

08 Apr '10

Hello everyone, I've put together a draft of my proposal for a GSoC project to work on graph layout algorithms. The proposal can be found here: http://socghop.appspot.com/gsoc/student_proposal/show/google/gsoc2010/djura… I'd really appreciate if I could get some feedback (especially from possible mentors, and maybe someone from the Parallel BGL ?). All suggestions are more than welcome. Thanks, Milos

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