October 2005 - Boost-users - lists.preview.boost.org

Boost Graph Library and Boehm Garbage Collector
by FBSL 08 Sep '08

08 Sep '08

Hello I am having trouble to garbage-collect adjacency_list<>. I have instanciated it with correctly garbage-collected vectors and lists (I have copied vecS and listS definitions, and added Boehm GC's default allocator so that they are garbage-collected). In my application I need to dynamically allocate many graphs, but it does not work, there is a (big) memory leak. Unfortunately, there is no template argument in adjacency_list<> to specify Boehm GC's allocator. Does anyone have a hint ? Snippet code "main.cpp" follows, compiled with Boost Graph Library 1.32, Boehm GC 6.4 and G++ 3.3.5, with command line : $ g++ -o main main.cpp -lgc -lgccpp -- #include <boost/graph/adjacency_list.hpp> #include <gc/gc_allocator.h> #include <gc/gc_cpp.h> #include <iostream> #include <vector> #include <list> using namespace std; using namespace boost; namespace boost { struct collected_vecS {}; struct collected_listS {}; template <class ValueType> struct container_gen<collected_vecS, ValueType> { typedef vector<ValueType,gc_allocator<ValueType> > type; }; template <class ValueType> struct container_gen<collected_listS, ValueType> { typedef list<ValueType,gc_allocator<ValueType> > type; }; template <> struct parallel_edge_traits<collected_vecS> { typedef allow_parallel_edge_tag type; }; template <> struct parallel_edge_traits<collected_listS> { typedef allow_parallel_edge_tag type; }; namespace detail { template <> struct is_random_access<collected_vecS> { enum { value = true }; typedef true_type type; }; } } typedef adjacency_list<collected_vecS, collected_vecS, directedS, no_property, no_property, no_property, collected_listS> graph; int main() { // leaks... while(true){ graph * g=new (UseGC) graph; for(unsigned int i=0; i<100; ++i){ add_vertex(*g); } for(unsigned int i=0; i<100; ++i){ for(unsigned int j=0; j<100; ++j){ add_edge(i,j,*g); } } } }

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[statechart] history transitions make state-local-storage "un-cool"
by Mick Hollins 26 Jun '08

26 Jun '08

Apologies if this has been discussed before, but I couldn't find any mention of it: I am currently using the history facility of boost::fsm. I've discovered that when I re-enter a state, X, via a history transition I don't actually re-enter the same instance of X that I was in before, but instead enter a newly constructed instance of X. I just checked the UML spec regarding history transitions and it says that "Any necessary entry actions are performed", so given that boost::fsm uses constructors to represent entry actions I guess a new instance of X has to be constructed to ensure UML compliance. My actual concern is the effect this has on the "coolness" of state-local-storage (see http://boost-sandbox.sourceforge.net/libs/statechart/doc/faq.html#Whats_so_…) It seems to me that state-local-storage, which I agree is generally cool, is particularly un-cool (and bug-inducing) in the presence of history transitions. I'm not sure what a good alternative is, but just thought I'd raise the discussion. cheers, mick PS: does the history facility display the same semantics in boost::statechart? I plan to move to statechart real soon now ...

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BGL: INTERNAL COMPILER ERROR in VC7.1
by Yariv Tal 10 Jun '07

10 Jun '07

This one was already posted by Nicholas Burlett awhile back (see http://lists.boost.org/MailArchives/boost-users/msg06534.php) but I have some new info that may help. The problem: ========= When compiling code that uses the boost.graph library the VC7.1 compiler shouts: c:\boost_1_32_0\boost\mpl\aux_\preprocessed\plain\apply_wrap.hpp(48) : fatal error C1001: INTERNAL COMPILER ERROR As Nicholas already noted, this seems to be due to some compiler problem with the boost.graph out_edge_iterators since it is caused by the following lines in my code: (FilteredGraphGenerator::FilteredGraph is a typedef of a boost::filtered_graph) typedef boost::graph_traits<FilteredGraphGenerator::FilteredGraph> ::out_edge_iterator oedge_iterator; oedge_iterator edgesItr, edgesEnd; boost::tie(edgesItr, edgesEnd) = boost::out_edges(itr->first, m_g.m_filteredGraph); while (edgesItr != edgesEnd) { // do anything! } In fact, it seems to be related to the operator!= between iterators (if the while loop is commented out it compiles). How ever, the error persists even after changing the operator!= to operator== : while (edgesItr == edgesEnd) { // do anything! } ========================================================================== Some findings: =========== * We used to use boost_1_30_0 and the code used to compile PERFECTLY. The problem only appeared after migrating to boost_1_32_0. * Calling directly to the "equal" function in iterator_core_access instead of the operator== works. typedef boost::graph_traits<FilteredGraphGenerator::FilteredGraph> ::out_edge_iterator oedge_iterator; oedge_iterator edgesItr, edgesEnd; boost::tie(edgesItr, edgesEnd) = boost::out_edges(itr->first,m_g.m_filteredGraph); while (boost::iterator_core_access::equal(edgesItr, edgesEnd, boost::mpl::true_())) { // do somthing } * The error message location is at the mpl::apply_wrap2 function. Any relation to the mpl::apply2 function used for declaring the operator== in the BOOST_ITERATOR_FACADE_INTEROP_HEAD macro? Have these functions changed since v1.30.0?

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[BGL] how to actually search with DFS/BFS?
by martin f krafft 22 Nov '06

22 Nov '06

This may seem like a silly question, but how does one actually search with DFS or BFS? Say I want to find the first node for which a predicate returns true in a BFS traversal starting at node N... The function signatures don't have a parameter for "criteria" or "predicate", so I guess it's up for a Visitor to implement such a check. What is not clear to me is how the visitor functions can break out of the search once a condition is true. Thanks, -- martin; (greetings from the heart of the sun.) \____ echo mailto: !#^."<*>"|tr "<*> mailto:" net@madduck invalid/expired pgp subkeys? use subkeys.pgp.net as keyserver! spamtraps: madduck.bogus(a)madduck.net "information superhighway" is just an anagram for "i'm on a huge wispy rhino fart".

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Building boost for 64-bit on AIX
by Patrik Jonsson 17 Aug '06

17 Aug '06

Hi, I'm trying to build boost (1.32.0) on an IBM SP2 under AIX5, using the 64-bit ABI. This is troublesome. I do: bjam "-sTOOLS=gcc" "-sGXX=g++ -maix64 -pthread" --prefix=$HOME --libdir=$HOME/lib64-gcc --includedir=$HOME/include-gcc install But it doesn't work. I get loads of errors like: gcc-Link-action bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/libboost_date_time-gcc-d-1_32.so ld: 0711-738 ERROR: Input file bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/greg_month.o: XCOFF32 object files are not allowed in 64-bit mode. collect2: ld returned 8 exit status set -e LIBPATH=bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true:$LIBPATH export LIBPATH "g++" -maix64 -pthread -g -fPIC -shared -o "bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/libboost_date_time-gcc-d-1_32.so" "bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/greg_month.o" "bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/greg_weekday.o" "bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/date_generators.o" ...failed gcc-Link-action bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/libboost_date_time-gcc-d-1_32.so... ...skipped <@boost!lib64-gcc>libboost_date_time-gcc-d-1_32.so for lack of <@boost!libs!date_time!build/libboost_date_time.so/gcc/debug/shared-linkable-true>libboost_date_time-gcc-d-1_32.so... It seems it's using -maix64 ok when trying to build the library, but not when compiling... Can anyone tell me what the proper way of building boost under these conditions are? Thanks, /Patrik Jonsson

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case insensitive less_than string comparison
by Matthias Kaeppler 07 Mar '06

07 Mar '06

Hi, I am aware that string_algo has an if_iequal functor. Is there also an equivalent for a less-than comparison? I have to compare strings ignoring the case but taking locales into account. Right now I'm calling boost::algorithm::to_lower on two copies of the original strings. I'm not so sure if this is very efficient when I'm comparing thousands of strings. Here's the functor as it is now: struct FileLessNameA : std::binary_function<const File&,const File&,bool> { bool operator() (const File& lhs, const File& rhs) const { std::string path1( lhs.get_name().c_str() ); std::string path2( rhs.get_name().c_str() ); boost::algorithm::to_lower( path1 ); boost::algorithm::to_lower( path2 ); return path1 < path2; } }; Any suggestions for improvements appreciated :) Regards, Matthias -- Matthias Kaeppler

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MultiArrays of Std::Lists: why const iterators?
by Joshua Schpok 12 Nov '05

12 Nov '05

I want to make a 3D array of std::lists: boost::multi_array<std::list<CSomething>,3> listbin; Then I'd like to actually use those lists: /// Walk through list at x,y,z for(std::list<CSomething>::iterator iter = listbin[x][y][z].begin(); reti != iter[x][y][z].end(); iter++) { iter->m_foo += 42; } But multi_array is giving me back *const* list iterators, producing the error: error: conversion from `std::_List_const_iterator<CSomething>' to non-scalar type `std::_List_iterator<CSomething>' requested Why is this so? I can trick the compiler by doing a cast like: std::list<CSomething>::iterator iter = ((std::list<CSomething>)listbin[x][y][z]).begin(); but this seems to poop out at runtime. Is there a proper way to do this? Joshua Schpok

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[BGL] a.k.a. [Graph] -- bundled properties not compiling for me under MS Dev
by Goldman, Jon 08 Nov '05

08 Nov '05

Hello, I am using Microsoft Development Environment 2002. I am trying to compile a Graph and use bundled properties. The error I am getting: \src\vtkSNL\Applications\RouteViz\rtrGraph.cxx(37) : error C2676: binary '[' : 'SimpleGraph' does not define this operator or a conversion to a type acceptable to the predefined operator \src\vtkSNL\Applications\RouteViz\rtrGraph.cxx(37) : error C2228: left of '.i' must have class/struct/union type The code snippet below exhibits the problem: struct nodeProp { int i; }; struct edgeProp { int i; }; typedef adjacency_list<boost::listS, boost::vecS, boost::bidirectionalS, nodeProp, edgeProp> SimpleGraph; void someFunc() { SimpleGraph someGraph(3); Graph::vertex_descriptor v = *vertices(someGraph).first; someGraph[v].i = 7; // This line is where the error is occuring } Anybody familiar with this problem? Thanks for looking this over, -Jon

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[iostreams] problem with gzip_compressor
by Tiago de Paula Peixoto 07 Nov '05

07 Nov '05

Hello. I've been experiencing the following problem with the gzip_compressor filter: It always writes data down the stream, regardless if any data has been written to the filtering_stream. Consider the following program: -------------------------------------------------------- #include <iostream> #include <fstream> #include <boost/iostreams/filtering_stream.hpp> #include <boost/iostreams/filter/gzip.hpp> using namespace std; using namespace boost; int main() { ofstream file; file.open("hello.gz", ios_base::out | ios_base::app | ios_base::binary); iostreams::filtering_stream<boost::iostreams::output> stream; stream.push(iostreams::gzip_compressor()); stream.push(file); return 0; } -------------------------------------------------------- If compiled as "test", the following behavior is observed: $ ./test; ls -l hello.gz -rw-r--r-- 1 count0 users 8 2005-10-30 19:51 hello.gz $ ./test; ls -l hello.gz -rw-r--r-- 1 count0 users 16 2005-10-30 19:51 hello.gz $ ./test; ls -l hello.gz -rw-r--r-- 1 count0 users 24 2005-10-30 19:51 hello.gz That is, it always adds 8 bytes to the file, despite the fact that nothing was written to the stream. To top things off, the data inside the file isn't even recognizable by gzip: $ gunzip hello.gz gunzip: hello.gz: not in gzip format When bzip2_compressor is used, this strange behavior doesn't happen, and the file remains with 0 bytes. I guess this is a bug, right? I'm using boost 1.33.0 with GCC 4.0.1 in a GNU/Linux system. Thanks for any help. -- Tiago de Paula Peixoto <tiago(a)forked.de>

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Translating an absolute path to a path relative to the current directory
by Hermann Rodrigues 06 Nov '05

06 Nov '05

Hi, I am running into the following problem these days: I need to translate an absolute path to a path relative to the current directory on Windows. The translation process need to include all required ".." directory specifiers in the path to make sure it can be accessed from the current directory. The following path samples may clarify the problem. -------------------------------------------------------------------------------- Current Directory: C:\x\y\z Absolute Path: C:\x\y\z\k\w.txt Translated Path: k\w.txt (C:\x\y\z is a common parent) Current Directory: C:\x\y\z Absolute Path: D:\a\b\c\d.txt Translated Path: D:\a\b\c\d.txt (no common parent found) Current Directory: C:\x\y\z Absolute Path: C:\x\k\w.txt Translated Path: ..\..\k\w.txt (C:\x is a common parent) -------------------------------------------------------------------------------- Is there any built-in support in the boost filesystem library to achieve such translation? At first I thought the path::relative_path could solve my problem but it does not seem to take into account the current directory, only the path itself. Any sugestion? Thanks in advance. Hermann

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