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Name generators for Boost Uuids
by Arindam Mukherjee 22 May '14

22 May '14

What is the specific use case for name generators for Boost Uuids? The generated uuids are still globally unique right, not just in the scope of a named domain? How is the algorithm different from the random generator? Are MAC addresses used in both cases? Thanks, Arindam

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[Xpressive] Placeholder for user defined assertion
by LOL 22 May '14

22 May '14

I am trying to use a placeholder object for the check function in an xpressive regex. The error I usually get is "error C2064: term does not evaluate to a function taking 1 arguments" Please see my example below that uses the three_or_six user-defined assertion as described at http://www.boost.org/doc/libs/1_51_0/doc/html/xpressive/user_s_guide.html#b…. I am using boost 1.51 and Visual Studio 2010 Express. This is a contrived example; the real reason I am trying to do this is because my assertion has state that is not known at the time the regex is compiled. In the interim I have worked around it by using static variables instead of placeholders but that makes for more brittle code than I would like. Also, is there any way to reuse the match_results objects that are created by the iterator syntax? Thanks, Michael Mitchell //Inspired by https://groups.google.com/forum/#!topic/boost-list/hTBAT7KMgd4 #include <iostream> #include <boost/xpressive/regex_actions.hpp> #include <boost/xpressive/xpressive_static.hpp> using namespace std; using namespace boost::xpressive; // A predicate that is true IFF a sub-match is // either 3 or 6 characters long. struct three_or_six { bool operator()(ssub_match const &sub) const { return sub.length() == 3 || sub.length() == 6; } }; int main(int argc, char* argv[]) { int cnt = 0; string a_str("a_aaaaa___a_aa_aaa_"); // match words of 3 characters or 6 characters (this works). sregex expr1 = (bow >> +_w >> eow)[ check(three_or_six()) ] ; placeholder<three_or_six> tos_ph; sregex expr2 = (bow >> +_w >> eow)[ check(tos_ph) ] ; // The above does not work (error C2064: term does not evaluate to a function taking 1 arguments) placeholder<three_or_six*> tos_ptr_ph; sregex expr3 = (bow >> +_w >> eow)[ check(*tos_ptr_ph) ] ; // The above does not work (error 2676: binary '&&' : 'three_or_six' does not define this operator or a converstion to a type acceptable to the predefinied operator) sregex_iterator iter1(a_str.begin(), a_str.end(), expr1); three_or_six tos; sregex_iterator iter2(a_str.begin(), a_str.end(), expr2, let(tos_ph = tos)); three_or_six* tos_ptr = new three_or_six(); sregex_iterator iter3(a_str.begin(), a_str.end(), expr3, let(tos_ptr_ph = tos_ptr)); return 0; }

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[ANN] libstudxml - modern XML API for C++
by Boris Kolpackov 21 May '14

21 May '14

Hi, libstudxml is an XML library for modern, standard C++. It has an API that I believe should have already been in Boost or even in the C++ standard library. The API was first presented at the C++Now 2014 conference. Based on the positive feedback and encouragement I received during the talk, I've decided to make the implementation generally available. As an example, we can parse this XML: <person id="123"> <name>John Doe</name> <age>23</age> <gender>male</gender> </person> With the following C++ code, which performs all the validation necessary for this XML vocabulary: enum class gender {...}; ifstream ifs (argv[1]); parser p (ifs, argv[1]); p.next_expect (parser::start_element, "person", content::complex); long id = p.attribute<long> ("id"); string n = p.element ("name"); short a = p.element<short> ("age"); gender g = p.element<gender> ("gender"); p.next_expect (parser::end_element); // person The API has the following interesting features: * Streaming pull parser and streaming serializer * Two-level API: minimum overhead low-level & more convenient high-level * Content model-aware (empty, simple, complex, mixed) * Whitespace processing based on content model * Validation based on content model * Validation of missing/extra attributes * Validation of unexpected events (elements, etc) * Data extraction to value types * Attribute map with extended lifetime (high-level API) libstudxml is compact, external dependency-free, and reasonably efficient. The XML parser is a conforming, non-validating XML 1.0 implementation that is based on tested and proven code. The library is released under the MIT license. More information, documentation, and source code are available from: http://www.codesynthesis.com/projects/libstudxml/ Or, you can jump directly to the API description with examples: http://www.codesynthesis.com/projects/libstudxml/doc/intro.xhtml#2 Enjoy, Boris

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Boost test and openmpi
by Martin Vymazal 21 May '14

21 May '14

Hello, I have the following code: #define BOOST_TEST_DYN_LINK #define BOOST_TEST_MODULE mpi_functionality #include <boost/test/unit_test.hpp> #include "mpi.h" struct MPI_Functionality_Fixture { MPI_Functionality_Fixture() { m_argc = boost::unit_test::framework::master_test_suite().argc; m_argv = boost::unit_test::framework::master_test_suite().argv; } int m_argc; char** m_argv; }; BOOST_FIXTURE_TEST_SUITE( MPI_Functionality_TestSuite, MPI_Functionality_Fixture ) BOOST_AUTO_TEST_CASE( mpi_functionality_parenv_init ) { MPI_Init(&m_argc,&m_argv); } BOOST_AUTO_TEST_CASE( mpi_functionality_parenv_finalize ) { MPI_Finalize(); } BOOST_AUTO_TEST_SUITE_END() The code compiles fine, but I have the following problem when I try to run it. When I run as 'mpirun ./my_executable' or 'mpirun -np 3 ./my_executable' everything goes fine. On the other hand, when I run as ./my_executable I get the following error: unknown location(0): fatal error in "mpi_functionality_parenv_finalize": unrecognized signal Outside of Boost, it is perfectly possible to write a program which calls MPI_Init and MPI_Finalize and it does not have to be used with mpirun. I wonder if this (different) behavior of Boost test is normal. I did not find any remarks regarding Boost test and mpi in the tutorial. Best regards, Martin Vymazal

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Wrapper for maybe an iterator
by Jens Müller 20 May '14

20 May '14

Hi, I am looking for an iterator that can be incremented safely (but not dereferenced) without when it has been default-constructed, and when it has been constructed with another iterator, it is just a proxy for that iterator. Is there such a thing in Boost? BR, Jens

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Graph Library Question
by Ken Kazinski 20 May '14

20 May '14

Hi, I was able to find the shortest distances between my starting node and the rest of the nodes. Now I would like to output the path between my starting node and destination node. I have tried a number of different examples but none of them seem to do what I want. I am pretty sure I need to use some type of get but I can not find it in the documentation. Thanks for any help.

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Re: [Boost-users] [Graph] CSR from list of tuples
by Jeremiah Willcock 20 May '14

20 May '14

Is there any that you could build three separate vectors for the different components? That would allow the storage from two of the vectors to be reused as-is in the CSR graph. Otherwise, the best you can do is probably to accept an extra copy (but you should be able to get it to that using multi-pass iteration over the input vector). -- Jeremiah Willcock <div>-------- Original message --------</div><div>From: Sensei <senseiwa(a)gmail.com> </div><div>Date:05/20/2014 9:52 AM (GMT-07:00) </div><div>To: boost-users(a)lists.boost.org </div><div>Subject: [Boost-users] [Graph] CSR from list of tuples </div><div> </div>Dear all, I need to construct (and use) a graph that can handle millions of nodes, with minimal overhead, and as suggested I am using a CSR graph. As I understand from the documentation, it is unmodifiable. Arcs are created at runtime in a parallel fashion, and my choice was to use a vector of std::tuple<std::size_t, std::size_t, int> (that is, node, node, weight) with Intel's TBB. This is the problem: can I avoid temporary vectors to construct my graph? Right now the only way I see is to create the vector of arcs (as std::pair) and the vector of weights, but this is a waste of time and memory. Do you have any helpful suggestions? Cheers & Thanks! _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Compiling with Python 3.3.5?
by Paul Hoffman 20 May '14

20 May '14

Greetings. I am compiling Boost 1.54.0 from source on a Debian 7.0.0 system built on a virtual machine. When that system has Python 3.1.5, Boost compiles. However, for a different program on that system, I need a newer Python. I started a new VM, installed Python 3.3.5 instead of 3.1.5, and tried to build Boost the same way. That dies, spewing a lot of stuff that looks like: ...found 10793 targets... ...updating 68 targets... gcc.compile.c++ bin.v2/libs/python/build/gcc-4.7/release/threading-multi/numeric.o In file included from ./boost/python/detail/prefix.hpp:13:0, from ./boost/python/numeric.hpp:8, from libs/python/src/numeric.cpp:6: ./boost/python/detail/wrap_python.hpp:50:23: fatal error: pyconfig.h: No such file or directory compilation terminated. "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pthread -fPIC -DBOOST_ALL_NO_LIB=1 -DBOOST_PYTHON_SOURCE -DNDEBUG -I"." -I"/usr/local/include/python3.3" -c -o "bin.v2/libs/python/build/gcc-4.7/release/threading-multi/numeric.o" "libs/python/src/numeric.cpp" ...failed gcc.compile.c++ bin.v2/libs/python/build/gcc-4.7/release/threading-multi/numeric.o... gcc.compile.c++ bin.v2/libs/python/build/gcc-4.7/release/threading-multi/list.o In file included from ./boost/python/detail/prefix.hpp:13:0, from ./boost/python/list.hpp:8, from libs/python/src/list.cpp:5: ./boost/python/detail/wrap_python.hpp:50:23: fatal error: pyconfig.h: No such file or directory compilation terminated. . . . I don't see anything on the requirements page about a particular version of Python, but I could have missed it. Clues greatly appreciated. --Paul Hoffman

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[Test] Boost.Test for Property Tree Issue
by Pritesh Acharya 19 May '14

19 May '14

Boost version: 1.55.0 OS: Windows 8 IDE: Visual Studio 2010 I have a small class which just parses a std::string using boost::property_tree::read_json. I'm trying to test my method with invalid input to make sure my method handles the exception. However, when I execute GetPropertyTreeFromJsonInValidInput2 (source code in attachment), I get exception in the visual studio itself and I have to break the execution. (snapshot is included in attachment). I'm a new user of boost, so don't know where to look for the solution.

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What is the best way to obtain a constant one for any numeric type?
by Javier Dehesa 19 May '14

19 May '14

Is there any trait in Boost that allows me to get the value of one for any numeric type? What I'm looking for is something that would work like the following: boost::numeric_traits<int>::one; // 1 boost::numeric_traits<long>::one; // 1L boost::numeric_traits<double>::one; // 1.0 boost::numeric_traits<float>::one; // 1.0f And so on. Does it exist, or something equivalent? I've looked into NumericConversion, but I haven't quite found something similar. What I'm using now is something equivalent to the following: template<class Number> Number one() { return Number(1); } Maybe this is safe enough? I know I can do this trait by myself, but I would like to avoid it if possible, specially considering that I'm working on an already complex Boost library. Thanks. -- Javier Dehesa

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