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[Tokenmap] A (perfect) hash container library chcked-in to sandbox (RFC)
by Slawomir Lisznianski 08 Mar '10

08 Mar '10

http://svn.boost.org/svn/boost/sandbox/tokenmap/libs/tokenmap/doc/html/inde… A tokenmap is a data structure that uniquely maps pseudo-random generated keys with elements of the collection. Boost.Tokenmap is a (perfect) hash container library for C++. An important distinction between tokenmap and other dictionary-like containers, such as std::map or Boost.Unordered, is that tokenmap generates keys internally (referred to as "tokens") rather than relying on user to provide them. Specifically, when a new element is inserted into the tokenmap, an apparently random key is returned back to the caller which uniquely maps to the stored element. The returned key can later be used in a very efficient lookup. Although the code and documentation are far from complete, the implementation in the repo is functional and hopefully serves as a basis for further work. Slawomir

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[Itl] Review
by Phil Endecott 08 Mar '10

08 Mar '10

My review of the proposed Interval Template Library follows. This is based only on studying the documentation, and previous discussion of the library on the Boost mailing list (e.g. http://lists.boost.org/Archives/boost/2009/03/149396.php ). Joachim has clearly put a lot of work into what is a substantial and well-documented library. Unfortunately, it seems to me that it is built on a weak foundation. One of the most well-known problems involving intervals is to determine which of a given set of intervals contains a particular point. How to store a set of intervals in such a way as to make this problem efficient has been extensively studied. If an "interval tree" (See e.g. Wikipedia: http://en.wikipedia.org/wiki/Interval_tree) is used, then the problem can be answered in logarithmic time and linear space. (More precisely: if there are N intervals in the container and M overlap the point of interest, finding them should take O(M + log N) time and the data structure should take O(N) space.) I was hoping to find that this library was an implementation of an interval tree. But it is not: it is built on top of normal standard-library containers. The implementation used can find the intervals that overlap a point in O(M + log N) time, but to do so it needs worst-case O(N^2) space and I think it needs O(N^2 log N) time to build that structure. Presumably this complexity is not an issue in Joachim's application. Unfortunately, library code will be used in many different applications including those where optimal complexity is required. For example, consider trying to store the lifespans of people in a genealogy program: recording a few thousand people living over a few hundred years would approach the worse-case space complexity and need megabytes of storage. Perhaps other reviewers will feel that there are sufficient applications where this library is suitable to justify its inclusion in Boost. My feeling is that since the interval tree data structure is so well known and its performance is so much better, we should not accept this library. Ideally it would be possible for Joachim to replace ITL's current standard containers with an interval tree implementation. Could an interval tree be implemented with an interval sufficiently similar to a std::set/map to make that possible, without losing the complexity benefits? Once again, I believe that apart from this weak foundation this looks like an excellent submission that is comprehensive and well-documented. Regards, Phil.

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[Review] ITL review starts today, February 18th
by Hartmut Kaiser 07 Mar '10

07 Mar '10

Hi all, The formal review of the Interval Template Library (ITL) starts today, February 18th, 2010 and will end February 27th, 2010. ITL is being developed by Joachim Faulhaber. ------------------------------------------------ About the library: The Interval Template Library (ITL) is a library of interval containers that facilitates computations on collections of intervals and associated values. Use cases of such computations typically occur in the date and time problem domain, when collections of time intervals with associated data are analyzed, combined and aggregated. But the scope of applications for interval containers is more general and not limited to date and time problems. Interval containers allow to access and manipulate collections of intervals on an abstract level as sets and maps (of elements), but also to exploit segmental information that is given by the interval borders. Interval containers are fairly generic. They can be instantiated with discrete domain (or key) types like integral numeric types or boost::date or time types. But they also work with continuous domain types like double, rational or string. Using the latter allows to represent infinite sets and maps. The interface of the interval containers strives to be very intuitive and in line with the stl and other boost libraries. * The set theoretic operations union, difference, intersection and symmetric difference are available as operators for all interval containers and for many useful overloads between them. * There is iterator support on the level of segments and interval containers can be combined with stl containers of intervals via stl algorithms. * For discrete domain types, element iterators are available which makes interval sets and maps models of SortedAssociative Containers so they can be used with many stl algorithms. All interval containers are addable and subtractable. The addability and subtractability concept of the ITL leads to a general mechanism of aggregation on interval_maps which is called 'aggregate on overlap'. Exploiting 'aggregate on overlap' allows to compute many useful aggregation results in a simple and abstract manner. The ITL's Set and Map concepts are defined by a signature and collections of laws or axioms. Those semantical constraints have been validated using automatic law based tests. This gives the library both a well founded formal specification and an unusual thorough test base. The ITL emerged out of real world use cases and is successfully used at Cortex Software GmbH since a couple of years in the production code of various applications. On the boost developer's list it has been proposed in four previews and a review request since May 2008 and has been refactored and refined according to boost standards and suggestions from the list. The ITL is available from the boost vault: http://www.boostpro.com/vault/index.php?action=downloadfile&filename=itl_3_2 _0.zip&directory=Containers Documentation is online available at: http://www.herold-faulhaber.de/boost_itl/doc/libs/itl/doc/html/index.html The current sources are in the sandbox: https://svn.boost.org/svn/boost/sandbox/itl/ ------------------------------------------------ Everybody on this list is invited to participate in this formal review. I hope to see your review of this library, including your vote, and I welcome your participation in the discussions on the Boost mailing list. Please always state in your review, whether you think the library should be accepted as a Boost library. Additionally, please consider giving feedback on the following general topics: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? Regards Hartmut Review Manager --------------- Meet me at BoostCon www.boostcon.com

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[Boost][Test] Small issue with explicit function initialization
by Sylvain Bougerel 07 Mar '10

07 Mar '10

Hi, I'm not sure if it's an issue or not. But I noticed that the given code does not compile: #define BOOST_TEST_MAIN #include <boost/test/included/unit_test.hpp> template <typename Tp1, typename Tp2> inline Tp2 stupid_cast (const Tp1& arg) { return static_cast<Tp2>(arg); } BOOST_AUTO_TEST_CASE( test_details_key ) { BOOST_CHECK(stupid_cast<float, int>(1.0) == 1); } It give the following error with g++ (GCC) 4.4.3: try.cpp:40:48: error: macro "BOOST_CHECK" passed 2 arguments, but takes just 1 try.cpp: In member function 'void test_details_key::test_method()': try.cpp:40: error: 'BOOST_CHECK' was not declared in this scope While the following does compile (and runs well): #define BOOST_TEST_MAIN #include <boost/test/included/unit_test.hpp> template <typename Tp1, typename Tp2> inline Tp2 stupid_cast (const Tp1& arg) { return static_cast<Tp2>(arg); } BOOST_AUTO_TEST_CASE( test_details_key ) { BOOST_CHECK((stupid_cast<float, int>(1.0) == 1)); // <----- I wrapped it in parenthesis } So I was wondering whether the BOOST_<level> macro (I did check that the others suffer the same problem) are expected to behave in this way, or they are just missing an extra layer of parenthesis around the arguments, or even GCC is at fault, or I'm missing something definitely... Regards, Sylvain

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Re: [boost] [Review] ITL review starts today, February 18th
by Brian Wood 07 Mar '10

07 Mar '10

Joachim Faulhaber writes: > Let me put it this way: > std::set : could be model of itl::Set, if operators were implemented > itl::set : is model of itl::Set > itl::interval_set : is model of itl::Set but implemented via intervals > boost::dynamic_bitset : is almost model of itl::Set but implemented > via arrays of machine words. Joachim and I have previously discussed the names of some of the classes in his library in the context of serialization: *http://preview.tinyurl.com/y86phqg* I don't have plans yet to add support for this library to the C++ Middleware Writer, but I would suggest that you consider where you will be able to come up with serialization support for the library. I believe your options will be to add it yourself with Boost Serialization or go without it. If you stick with the names of some of the classes that you have today, at the very least, I'll put off developing marshalling support for the library. Brian Wood http://webEbenezer.net (651) 251-9384 "Then Samuel took a rock and set it up between Mizpah and Shen. He named it Ebenezer [Rock of Help] and said, 'Until now the L-RD has helped us.'"

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[transact] Handling with user exceptions
by vicente.botet 07 Mar '10

07 Mar '10

Hi, I would like to initiate a discussion on how to manage with user exceptions. Here follows some thougth I'm implementing in Boost.STM. There are two main ways to manage with user exceptions: * exceptions commit transactions - corresponds to the current C++ behavior * exceptions abort on exit - corresponds to rollback The behavior associated to the curent language-like macros is to throw the catched exception. In this case, the exception shouldn't contain references to transaction specific objects. I was wondering if we cannot add a second family of macros that before a user exception leaves the transaction block the transaction is commited. BOOST_TRANSACT_A_ family will abort the transaction on user exception BOOST_TRANSACT_C_ family will commit the transaction on user exception This will allows to explore which both approaches, and see which approach is more usable, or if there is an approach that is better adapted to some particuler contexts. * Exceptions Commit Transactions - How to get this? While trying to commit on destruction we have catched any exception to release the commit_on_destruction variable. commit_on_destruction __comm( __txn ) ; t ry { i f ( false ) ; else / / to for ce a sentence / / t r a n s a c t i o n sentence } catch ( . . . ) { __comm. release ( ) ; throw ; } To make exception commit transactions by default, we should not release the committer. However, we need to avoid exception throw by commit when the transaction has been set as forced to abort or during unwinding exception. commit_on_destruction __comm( __txn ) ; t ry { <sentence > } catch ( . . . ) { i f ( __txn_.forced_to_abort ( ) ) __comm.release ( ) ; else __comm.commit ( ) ; throw ; } We need how to override the default behavior. If we have Exceptions Commit Transactions - we can abort the transaction in two ways: * Explicit try-block to Abort Transactions * Explicitly abort before throw - Explicit try-block to Abort Transactions The user may want the exception abort the transaction while leaving the transaction block. The user must explicitly state that this is the desired behavior by adding a try-catch block as shown below: BOOST_STM_C_TRANSACTION t ry { / / t r a n s a c t i o n block } catch (Ex&) { BOOST_STM_ABORT( ) ; throw ; } BOOST_STM_C_END_TRANSACTION; - Explicitly abort before throw The user may want the transaction to be aborted before throwing an exception. The user may explicitly state that this is the desired either by setting the current transaction as forced to abort, BOOST_STM_ABORT( ) ; throw except ( ) ; or by throwing the exception using the macro : / / . . . BOOST_STM_ABORT_AND_THROW( except ( ) ) ; / / . . . If we have Exceptions Abort on Exit we can commit the transaction as follows: - Explicit try-block to Commit Transactions The user must explicitly state that this is the desired behavior by adding a try-catch block as shown below: BOOST_STM_TRANSACTION t ry { / / t r a n s a c t i o n block } catch (Ex &ex ) { BOOST_STM_COMMIT( ) ; throw ; } BOOST_STM_END_TRANSACTION; boost::exception_ptr error; BOOST_STM_TRANSACTION t ry { / / t r a n s a c t i o n block } catch (Ex &) { error=boost::current_exception(); } BOOST_STM_END_TRANSACTION; if( error) boost::rethrow_exception(error); } Please let me know what do you think? Do you find this useful? Should we provide two families of macros? Best regards, _____________________ Vicente Juan Botet Escribá

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[Review] The review of the ITL library ends today, March 7th
by Hartmut Kaiser 07 Mar '10

07 Mar '10

Hey all, The review of Joachim Faulhabers ITL library ends today, March 7th 2010. Please get your reviews in today or get in contact with me to agree on some offline schedule. Regards Hartmut Review Manager --------------- Meet me at BoostCon www.boostcon.com

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Re: [boost] [transact] transaction language macros (was: Re: [transact] code in sandbox)
by vicente.botet 07 Mar '10

07 Mar '10

Hi, ----- Original Message ----- From: <strasser(a)uni-bremen.de> To: "vicente.botet" <vicente.botet(a)wanadoo.fr> Sent: Saturday, March 06, 2010 3:55 PM Subject: Re: [boost] [transact] transaction language macros (was: Re: [transact] code in sandbox) > > hi again, > > another thing, are you experienced with the various parsing libraries > of boost? No, I have made only some toy examples with Spirit long time ago. > I know that they're not capable of analyzing C++ code, but it seems to > me that the code transformation required for our little language > extension is fairly simple. > > boost has compliant preprocessor, so macros aren't a problem. > the most complicated thing would be to detect if a transaction is in a > user-loop or not, so the grammar would have to be able to read > for/while/... loops and correctly parse c++ scopes. > does anything like that already exist? To do something like that I will use LLVM that gives already this possibility. Of course starting to use LLVM will be not easy, but will open much more possibilities than a specific parsing. Best, Vicente

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Re: [boost] [Boost-users] [Review] ITL review starts today, February 18th
by Joachim Faulhaber 06 Mar '10

06 Mar '10

Hi John, thank you for reviewing the ITL library! 2010/3/3 John Reid <j.reid(a)mail.cryst.bbk.ac.uk>: > Hartmut Kaiser wrote: >> >> The ITL is available from the boost vault: >> >> http://www.boostpro.com/vault/index.php?action=downloadfile&filename=itl_3_2 >> _0.zip&directory=Containers > > I have to say first I have been evaluating the version of ITL called > itl_plus_3_2_1 rather than the version in the boost vault. Perhaps someone > can tell me whether that is a big mistake or not. Using itl_plus_3_2_1 is completely ok. It is a later release than the review version itl_3_2_0. But the differences are marginal. Also itl_plus_3_2_1 contains more than the core library that is submitted for review. But you did not refer to these parts. So everything is fine. >> Please always state in your review, whether you think the library should >> be >> accepted as a Boost library. > > I think it should be accepted subject to the inclusion of an interval tree > implementation. > >> >> - What is your evaluation of the design? > > I suspect that making the open/closedness of an interval a template > parameter would suit more users although I don't have a strong opinion on > this one. There has been a discussion on this point already. http://permalink.gmane.org/gmane.comp.lib.boost.devel/199905 For continuous data types it seems like interval bounds are needed as data member. For intervals of integral types the bound_type can be a static property. I will adapt the design in this point. >> - What is your evaluation of the implementation? > > I would have liked to see interval trees in the implementation. For what > I've needed the library for so far this has not been a problem as most of > the intervals don't overlap. In the future I can see use cases where the > lack of interval trees would make the library impractical. I don't know how > much impact adding an interval tree implementation would have on the > existing interface. I think the current implementation has its value and application. It should not and can not completely be replaced by an implementation based on an interval_tree. This would improve certain use cases but lead to problems in others. I will report on this in more detail. An interval_tree based split_interval_map will be a valuable optimization that should be done as an additional class template. The current implementation is fully functional, correct, useful and efficient in most cases of application. >> - What is your evaluation of the documentation? > > Good. A tutorial would be a welcome addition. Some functions were > undocumented, I'm assuming they're documented in the review version. The "handcrafted" documentation relates to the major interface of overloaded functions and function templates. In order to keep that short, more specific functions are only documented in the part of the documentation that is generated from doxygen comments: http://www.joachim-faulhaber.de/boost_itl/doc/libs/itl/doc/html/interval_te… And yes, there may be few that have been forgotten. Please tell me, which ones you missed specifically. >> - What is your evaluation of the potential usefulness of the library? > > Very useful. It seems to have many applications in several different > domains. > >> - Did you try to use the library? With what compiler? Did you have any >> problems? > > I used gcc 4.4.1 and boost.python to make a python module for most of the > main elements of the library. I used this module successfully in an > application in genomics. However so far I have only had use for the > SplitIntervalMap so I have not used most of the library. > >> - How much effort did you put into your evaluation? A glance? A quick >> reading? In-depth study? > > A reasonable amount - enough to get up to speed and use the library. > >> - Are you knowledgeable about the problem domain? > > Not especially. > Thank you again. Best regards, Joachim

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[BGL] Testing a graph for bipartiteness
by Matthias Walter 06 Mar '10

06 Mar '10

Hi, I'm working on a project where I need to determine whether a given graph is bipartite (possible yielding certificates for the two cases). As such a test can be perfectly implemented via BFS and visitor patterns, I wondered why there is no implementation in the BGL. Is there any reason or am I just to blind to find it? If I'm forced to write my own one, how about submitting it to BGL? best regards Matthias Walter

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