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[BGL] Cannot use vertex indices managed through bundled properties with r_c_shortest_path if EdgeList is listS
by potato_research 05 Sep '13

05 Sep '13

As per the thread topic. Given the following minimal (not-)working example: http://pastebin.com/6zpwCb4X I receive the following compilation error: /usr/local/include/boost/graph/r_c_shortest_paths.hpp:244:50: error: invalid conversion from 'boost::graph_traits<boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, VertexProperty, EdgeProperty> >::vertex_descriptor {aka void*}' to 'int' [-fpermissive] int i_cur_resident_vertex_num = cur_label->resident_vertex; If I change my graph from: adjacency_list<listS, listS, bidirectionalS, VertexProperty, EdgeProperty> to adjacency_list<listS, vecS, bidirectionalS, VertexProperty, EdgeProperty> everything seems to be working fine. However, I need to use listS in my code for iterator validity purposes. Is it possible to use r_c_shortest_paths with a graph with listS EdgeList? If so, how? Thanks. -- View this message in context: http://boost.2283326.n4.nabble.com/BGL-Cannot-use-vertex-indices-managed-th… Sent from the Boost - Users mailing list archive at Nabble.com.

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[chrono] this_thread::sleep_for milliseconds
by Michael Powell 05 Sep '13

05 Sep '13

Hello, I am working on a daemon that involves a sleep_for in the main loop, while worker-threads do the "heavier" lifting in the daemon. I have a couple of signals wired up to respond to terminal, kill or other requests, as per daemonization-guidelines. Question for the list, I gather that thread-sleeps are interrupted when these type of signals occur? Which is fine, I don't need to re-sleep, per se, as some examples seem to suggest. But I do guard a flag in a mutex-critical-section and flag whether to stop running the main loop, which then joins the worker threads. Is this about right as far as daemon, thread/sleep, worker thread approaches are concerned? It seems like it to me, but I thought I should run it past the list to see if there are any pearls of wisdom on the subject. Thank you... Regards, Michael Powell

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[units] coulombs to milliamp-hours
by Michael Powell 05 Sep '13

05 Sep '13

Hello, I am looking for a Coulombs to mAh (milliamp-hours) converter. It's conversion is a ratio I think: 1000 / 3600 (A -> mA, seconds -> hours). Haven't checked yet, but does SI include Coulombs? Or for that matter Amperes, where Coulomb = A s, I think. Thank ye. Regards, Michael Powell

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[multi_index] sorted iteration of values
by Mathieu Champlon 05 Sep '13

05 Sep '13

Hello, I'm trying to use Boost.MultiIndex to store my data. The idea is to have a kind of bidirectional multimap (I initially started with Boost.BiMap) which could model : std::multimap< SomeType*, std::set< int > > left; std::multimap< int, SomeType*> right; I'll need to : . insert obviously . remove all ints based on a SomeType* . remove one given (SomeType*,int) . for a given int iterate on all SomeType* . for a given SomeType* iterate in order on all ints What I have so far is : typedef SomeType* First; typedef int Second; struct Value { First first; Second second; }; boost::multi_index::multi_index_container< Value, boost::multi_index::indexed_by< boost::multi_index::ordered_unique< boost::multi_index::composite_key< Value, boost::multi_index::member< Value, First, &Value::first >, boost::multi_index::member< Value, Second, &Value::second > > >, boost::multi_index::ordered_non_unique< boost::multi_index::member< Value, Second, &Value::second > >, boost::multi_index::ordered_non_unique< boost::multi_index::member< Value, First, &Value::first > > > > data; This works, except for the ints iteration based on a given SomeType* because I need them to be sorted, and they're not, e.g. auto range = data.get< 2 >().equal_range( someTypePtr ); for( auto it = range.first; it != range.second; ++it ) ; does not iterate in a sorted order. Is there a way to achieve this without manually sorting the iterated values ? Thank you ! MAT.

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boost::multiprecision::cpp_int encoding and decoding little endian byte arrays
by Steffen Heil (Mailinglisten) 05 Sep '13

05 Sep '13

Hello I need to decode/encode cpp_int values from/into byte arrays. The encoding must be shortest little endian two's complement representation of the value. For example: 00 = 0 01 = 1 ff = -1 ff:7f = 32767 01:80 = -32767 00:80:00 = 32768 00:80 = -32768 01:80:00 = 32769 ff:7f:ff = -32769 ff:ff:ef:9c:d2:40:43:da:4f:40:6b:06:6a:cd:92:c2:93:bf:a4:5c:c3:f1:29:63:1d = 184467440737095516151844674407370955161518446744073709551615 01:00:10:63:2d:bf:bc:25:b0:bf:94:f9:95:32:6d:3d:6c:40:5b:a3:3c:0e:d6:9c:e2 = -184467440737095516151844674407370955161518446744073709551615 I found a way to archive my goal (see below), but it seems way to complex and too inefficient. For encoding I basically converting the cpp_int to a uint8_t to get 8 bit and then shift the cpp_int by 8, creating a new cpp_int... Twice (once to compute it's length, again to encode it). For decoding I already shift the byte read to the "right" position and "|=" it into the existing cpp_int. Isn't there an easier way access the binary representation of an cpp_int? Regards, Steffen --- #include <iostream> #include <boost/multiprecision/cpp_int.hpp> using namespace std; using namespace boost::multiprecision; size_t binLength( cpp_int value ) { if ( value.is_zero() ) return 1; if ( value.sign() < 0 ) value = ~ value; size_t length = 0; uint8_t lastByte; do { lastByte = value.convert_to<uint8_t>(); value >>= 8; length ++; } while ( ! value.is_zero() ); if ( lastByte >= 0x80 ) length ++; return length; } void binEncode( cpp_int value, uint8_t* output, size_t length ) { if ( value.is_zero() ) *output = 0; else if ( value.sign() > 0 ) while ( length -- > 0 ) { *( output ++ ) = value.convert_to<uint8_t>(); value >>= 8; } else { value = ~ value; while ( length -- > 0 ) { *( output ++ ) = ~ value.convert_to<uint8_t>(); value >>= 8; } } } cpp_int binDecode( uint8_t* input, size_t length ) { boost::multiprecision::cpp_int result( 0 ); int bits = - 8; while ( length -- > 1 ) result |= (boost::multiprecision::cpp_int) *( input ++ ) << ( bits += 8 ); uint8_t a = *( input ++ ); result |= (boost::multiprecision::cpp_int) a << ( bits += 8 ); if ( a >= 0x80 ) result |= (boost::multiprecision::cpp_int) - 1 << ( bits + 8 ); return result; } void test( string s ) { cpp_int x( s ); uint8_t buffer[ 100 ]; size_t length = binLength( x ), index = 0; binEncode( x, buffer, length ); cpp_int y = binDecode( buffer, length ); cout << hex << setw( 2 ) << setfill( '0' ) << (int) buffer[ 0 ]; while ( -- length > 0 ) cout << ':' << setw( 2 ) << setfill( '0' ) << (int) buffer[ ++ index ]; cout << " = " << dec << setw( 1 ) << x << endl; if ( x != y ) cerr << "failed" << endl; } int main( int argc, const char* argv[] ) { test( "0" ); test( "1" ); test( "-1" ); test( "32767" ); test( "-32767" ); test( "32768" ); test( "-32768" ); test( "32769" ); test( "-32769" ); test( "184467440737095516151844674407370955161518446744073709551615" ); test( "-184467440737095516151844674407370955161518446744073709551615" ); }

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Re: [Boost-users] Why fusion::map<> types not the same?
by Sergey Zhuravlev 04 Sep '13

04 Sep '13

This is bug. You should add ticket to bugtracker. Try to use boost\fusion\result_of::as_map as workaround.

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[Log] How to use a channel that is constant per file?
by Timo Schmiade 03 Sep '13

03 Sep '13

Hi all, I want to use boost's log library to output messages to the console which feature a per-message severity and a per-file channel. I already tried two approaches, none of which was satisfying: === 1. approach === The class boost::log::sources::severity_channel_logger supports both severity and channel and I could define it in each source file like so: --- 8< --- BOOST_LOG_INLINE_GLOBAL_LOGGER_DEFAULT( log, boost::log::sources::severity_channel_logger< boost::log::trivial::severity_level, std::string > ) --- >8 --- Unfortunately, using it like this requires me to redundantly add the channel to each log message, which is very inconvenient because it is the same for all logs in the file. --- 8< --- // Message.cpp BOOST_LOG_CHANNEL_SEV(log, Message, trace) << "Hello, world"; --- >8 --- === 2. approach === I defined my logger like this: --- 8< --- BOOST_LOG_INLINE_GLOBAL_LOGGER_DEFAULT( log, boost::log::sources::severity_logger< boost::log::trivial::severity_level > ) --- >8 --- Then, in each file, I manually set the "Channel" attribute for the logger, like so: --- 8< --- // Message.cpp log::get().add_attribute( "Channel", boost::log::attributes::make_constant("Message")); --- >8 --- This works, but as the "log" object seems to be stored globally, I would have to "invent" new names for the logger object in each file. This is both insecure and prevents the usage of macros (I think). So here's the question: What would be the recommended / a convenient way to add a per-file constant channel to log messages? Thanks in advance! Timo

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Why fusion::map<> types not the same?
by niXman 03 Sep '13

03 Sep '13

Hi, Why 'type' is not same as 'expected' in the example below? using origin = boost::fusion::map< boost::fusion::pair<int, int> >; using expected = boost::fusion::map< boost::fusion::pair<int, int> ,boost::fusion::pair<char, char> >; using type = boost::fusion::result_of::push_back< origin ,boost::fusion::pair<char, char> >::type; static_assert(std::is_same<expected, type>::value, "error!"); The second question is, how can I get the same type as 'expected' when using 'result_of::push_back<>::type' ? -- Regards, niXman ___________________________________________________ Dual-target(32 & 64-bit) MinGW compilers for 32 and 64-bit Windows: http://sourceforge.net/projects/mingwbuilds/ ___________________________________________________ Another online IDE: http://liveworkspace.org/

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[asio][ssl] why the error of " decryption failed or bad record mac" happen?
by lx 03 Sep '13

03 Sep '13

I use the asio and ssl , the error message of " decryption failed or bad record mac" happen some tiems. What are the possible causes? Thank you

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[spirit] Parsing std::string phrase into attribute struct
by Michael Powell 03 Sep '13

03 Sep '13

Hello, Question re: parsing string into a Fusion-adapted struct. First, magic! Wow, I like it. Question about the immediate result, true/false. Let's say the operation fails for whatever reason. In our use-case, we'll be reading some text in from a Linux /sysfs -provided API. We'll parse the contents into a struct instance. If the operation fails for whatever reason, does not match the grammar, are any values mapped into the structure? My first guess, is possibly: a partial (though still failing) match, would partially populate the instance? I am using the employee-example as our boiler plate. http://www.boost.org/doc/libs/1_54_0/libs/spirit/example/qi/employee.cpp The outcome of which would be whether to consider the instance valid for reporting further into user-space, or what else to do with the outcome from there. Thank you... Regards, Michael Powell

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