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[Proto] Questions about deep_copy
by Kim Kuen Tang 10 May '09

10 May '09

Hi all, consider the following code: std::vector<double> a(10,1.0), b(10,2.0); BOOST_AUTO( temp , proto::as_expr<MixedDomain>(a+b+0.1) ); // is the function proto::as_expr<MixedDomain>() needed? temp[0]; Here the expression a +b+ 0.1 is created by the MixedDomain as it is from the mixed example. And the operator[] is definde by: typedef typename boost::remove_reference< typename boost::result_of<Begin(MixedExpr<Expr> const & )>::type>::type Expr2; typedef typename proto::result_of::eval<Expr2, DereferenceCtx const>::type result_type; result_type operator[](std::size_t index) const { Expr2 expr2 = Begin()(*this); DereferenceCtx const deref = {}; return proto::eval(expr2, deref); } But the code crashes during runtime. The reason is that the number 0.1 is held by reference. So the number 0.1 goes out of scope before i try to evaluate the expression temp[0]; A way to solve this problem is to deep copy the expression with deep_copy. But on the other hand i do not want to copy the two vectors a and b. So i am asking what is the best way to solve this problem? Can this problem be solved by defining a Grammar that copies the number 0.1? Or do i need to extend the deep_copy by deep_copy_if<double>() (a+b+0.1). It should copy the terminal only if it matches the specified type. Thanks for your help. B/Rgds Kim Here is the whole code: //[ Mixed /////////////////////////////////////////////////////////////////////////////// // Copyright 2008 Eric Niebler. Distributed under the Boost // Software License, Version 1.0. (See accompanying file // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) // // This is an example of using BOOST_PROTO_DEFINE_OPERATORS to Protofy // expressions using std::vector<> and std::list, non-proto types. It is a port // of the Mixed example from PETE. // (http://www.codesourcery.com/pooma/download.html) #include <list> #include <cmath> #include <vector> #include <complex> #include <iostream> #include <stdexcept> #include <boost/proto/core.hpp> #include <boost/proto/debug.hpp> #include <boost/proto/context.hpp> #include <boost/proto/transform.hpp> #include <boost/proto/proto_typeof.hpp> #include <boost/proto/deep_copy.hpp> #include <boost/utility/enable_if.hpp> #include <boost/typeof/std/list.hpp> #include <boost/typeof/std/vector.hpp> #include <boost/typeof/std/complex.hpp> #include <boost/type_traits/remove_reference.hpp> #include <boost/utility/result_of.hpp> #include <boost/typeof/typeof.hpp> namespace proto = boost::proto; namespace mpl = boost::mpl; using proto::_; template<typename Expr> struct MixedExpr; template<typename Iter> struct iterator_wrapper { typedef Iter iterator; iterator_wrapper(Iter it) :it(it) {}; Iter it; }; struct begin_iter :proto::callable { template<class Sig> struct result; template<class This, class Cont> struct result<This(Cont)> : proto::result_of::as_expr< iterator_wrapper<typename boost::remove_reference<Cont>::type::const_iterator> > {}; template<class Cont> typename result<begin_iter(Cont const&)>::type operator()(Cont const& cont) const { iterator_wrapper<typename Cont::const_iterator> it(cont.begin()); return proto::as_expr(it); } }; template<typename Num> struct num_wrapper { typedef Num numeric; num_wrapper(Num num) :num_(num) { //BOOST_MPL_ASSERT( (boost::is_reference<Num>) ); }; Num num_; }; struct begin_num :proto::callable { template<class Sig> struct result; template<class This, class Cont> struct result<This(Cont)> : proto::result_of::make_expr<proto::tag::terminal ,num_wrapper< typename boost::remove_const< typename boost::remove_reference<Cont>::type >::type > > {}; template<class Cont> typename result<begin_num(Cont const)>::type operator()(Cont const cont) const { //BOOST_MPL_ASSERT( (boost::is_reference<result<begin_num(Cont const&)>::type>) ); num_wrapper<Cont> num(cont); return proto::make_expr<proto::tag::terminal>(num); } }; // Here is a grammar that replaces vector and list terminals with their // begin iterators struct Begin : proto::or_< proto::when< proto::terminal<std::vector<_,_> >, begin_iter(proto::_value)> ,proto::when< proto::terminal<std::list<_,_> >, begin_iter(proto::_value)> ,proto::when<proto::terminal<double>, begin_num(proto::_value) > ,proto::when<proto::terminal<_> > ,proto::nary_expr<_ , proto::vararg<Begin> > > {}; struct DereferenceCtx { template<typename Expr,typename EnableIf=void> struct eval : proto::default_eval<Expr, DereferenceCtx const> {}; template<typename Expr> struct eval<Expr, typename boost::enable_if< proto::matches<Expr, proto::terminal< iterator_wrapper<_> > > >::type > { typedef typename proto::result_of::value<Expr>::type IteratorWrapper; typedef typename IteratorWrapper::iterator iterator; typedef typename std::iterator_traits<iterator>::reference result_type; template<typename Expr> result_type operator()(Expr &expr,DereferenceCtx const&) { return *proto::value(expr).it; } }; template<typename Expr> struct eval<Expr, typename boost::enable_if< proto::matches<Expr, proto::terminal< num_wrapper<_> > > >::type > { typedef typename proto::result_of::value<Expr>::type NumWrapper; typedef typename NumWrapper::numeric result_type; template<typename Expr> result_type operator()(Expr &expr,DereferenceCtx const&) { return proto::value(expr).num_; } }; }; struct IncrementCtx { template<typename Expr,typename EnableIf=void> struct eval : proto::null_eval<Expr, IncrementCtx const> {}; template<typename Expr> struct eval<Expr, typename boost::enable_if< proto::matches<Expr, proto::terminal<iterator_wrapper<_> > > >::type> { typedef void result_type; template<typename Expr> result_type operator()(Expr& expr, IncrementCtx const & ) { ++proto::value(expr).it; } }; }; struct AdvanceCtx { std::size_t index_; template<typename Expr,typename EnableIf=void> struct eval : proto::null_eval<Expr, AdvanceCtx const> {}; template<typename Expr> struct eval<Expr, typename boost::enable_if< proto::matches<Expr, proto::terminal<iterator_wrapper<_> > > >::type> { typedef void result_type; template<typename Expr> result_type operator()(Expr& expr, AdvanceCtx const & ctx) { std::advance(proto::value(expr).it, ctx.index_); } }; }; // A grammar which matches all the assignment operators, // so we can easily disable them. struct AssignOps : proto::switch_<struct AssignOpsCases> {}; // Here are the cases used by the switch_ above. struct AssignOpsCases { template<typename Tag, int D = 0> struct case_ : proto::not_<_> {}; template<int D> struct case_< proto::tag::plus_assign, D > : _ {}; template<int D> struct case_< proto::tag::minus_assign, D > : _ {}; template<int D> struct case_< proto::tag::multiplies_assign, D > : _ {}; template<int D> struct case_< proto::tag::divides_assign, D > : _ {}; template<int D> struct case_< proto::tag::modulus_assign, D > : _ {}; template<int D> struct case_< proto::tag::shift_left_assign, D > : _ {}; template<int D> struct case_< proto::tag::shift_right_assign, D > : _ {}; template<int D> struct case_< proto::tag::bitwise_and_assign, D > : _ {}; template<int D> struct case_< proto::tag::bitwise_or_assign, D > : _ {}; template<int D> struct case_< proto::tag::bitwise_xor_assign, D > : _ {}; }; // A vector grammar is a terminal or some op that is not an // assignment op. (Assignment will be handled specially.) struct MixedGrammar : proto::or_< proto::when< proto::terminal<double const&> , begin_num(proto::_value)> , proto::terminal<_> , proto::and_< proto::nary_expr<_, proto::vararg<MixedGrammar> > , proto::not_<AssignOps> > > {}; // Expressions in the vector domain will be wrapped in VectorExpr<> // and must conform to the VectorGrammar struct MixedDomain : proto::domain<proto::generator<MixedExpr>, MixedGrammar> {}; // Here is MixedExpr, a wrapper for expression types in the MixedDomain. template<typename Expr> struct MixedExpr : proto::extends<Expr, MixedExpr<Expr>, MixedDomain> { explicit MixedExpr(Expr const &expr) : proto::extends<Expr, MixedExpr<Expr>, MixedDomain>(expr) {} typedef typename boost::remove_reference< typename boost::result_of<Begin(MixedExpr<Expr> const & )>::type>::type Expr2; typedef typename proto::result_of::eval<Expr2, DereferenceCtx const>::type result_type; result_type operator[](std::size_t index) const { //BOOST_MPL_ASSERT( (boost::is_reference<Expr2>) ); Expr2 expr2 = Begin()(*this); AdvanceCtx const adv = {index}; proto::eval(expr2, adv); DereferenceCtx const deref = {}; return proto::eval(expr2, deref); } private: // hide this: //using proto::extends<Expr, MixedExpr<Expr>, MixedDomain>::operator []; }; // Define a trait type for detecting vector and list terminals, to // be used by the BOOST_PROTO_DEFINE_OPERATORS macro below. template<typename T> struct IsMixed : mpl::false_ {}; template<typename T, typename A> struct IsMixed<std::list<T, A> > : mpl::true_ {}; template<typename T, typename A> struct IsMixed<std::vector<T, A> > : mpl::true_ {}; namespace MixedOps { // This defines all the overloads to make expressions involving // std::vector to build expression templates. BOOST_PROTO_DEFINE_OPERATORS(IsMixed, MixedDomain) struct assign_op { template<typename T, typename U> void operator ()(T &t, U const &u) const { t = u; } }; struct plus_assign_op { template<typename T, typename U> void operator ()(T &t, U const &u) const { t += u; } }; struct minus_assign_op { template<typename T, typename U> void operator ()(T &t, U const &u) const { t -= u; } }; struct sin_ { template<typename Sig> struct result; template<typename This, typename Arg> struct result<This(Arg)> : boost::remove_const<typename boost::remove_reference<Arg>::type> {}; template<typename Arg> Arg operator ()(Arg const &a) const { return std::sin(a); } }; template<typename A> typename proto::result_of::make_expr< proto::tag::function , MixedDomain , sin_ const , A const & >::type sin(A const &a) { return proto::make_expr<proto::tag::function, MixedDomain>(sin_(), boost::ref(a)); } template<typename FwdIter, typename Expr, typename Op> void evaluate(FwdIter begin, FwdIter end, Expr const &expr, Op op) { IncrementCtx const inc = {}; DereferenceCtx const deref = {}; typename boost::result_of<Begin(Expr const &)>::type expr2 = Begin()(expr); for(; begin != end; ++begin) { op(*begin, proto::eval(expr2, deref)); proto::eval(expr2, inc); } } template<typename Vector, typename Expr> Vector& assign(Vector &arr,Expr const &expr) { evaluate(arr.begin(),arr.end(),proto::as_expr<MixedDomain>(expr),assign_op()); return arr; } // Add-assign to a vector from some expression. template<typename T, typename A, typename Expr> std::vector<T, A> &operator +=(std::vector<T, A> &arr, Expr const &expr) { evaluate(arr.begin(), arr.end(), proto::as_expr<MixedDomain>(expr), plus_assign_op()); return arr; } // Add-assign to a list from some expression. template<typename T, typename A, typename Expr> std::list<T, A> &operator +=(std::list<T, A> &arr, Expr const &expr) { evaluate(arr.begin(), arr.end(), proto::as_expr<MixedDomain>(expr), plus_assign_op()); return arr; } // Minus-assign to a vector from some expression. template<typename T, typename A, typename Expr> std::vector<T, A> &operator -=(std::vector<T, A> &arr, Expr const &expr) { evaluate(arr.begin(), arr.end(), proto::as_expr<MixedDomain>(expr), minus_assign_op()); return arr; } // Minus-assign to a list from some expression. template<typename T, typename A, typename Expr> std::list<T, A> &operator -=(std::list<T, A> &arr, Expr const &expr) { evaluate(arr.begin(), arr.end(), proto::as_expr<MixedDomain>(expr), minus_assign_op()); return arr; } } int main() { using namespace MixedOps; int n = 10; std::vector<int> a,b,c,d; std::list<double> e; std::list<std::complex<double> > f; int i; for(i = 0;i < n; ++i) { a.push_back(i); b.push_back(2*i); c.push_back(3*i); d.push_back(i); e.push_back(0.0); f.push_back(std::complex<double>(1.0, 1.0)); } BOOST_AUTO(temp ,c + a + 0.1 ); for(int i=0, end=n;i<end;++i) std::cout<<temp[i]<<"\t"; //f -= sin(0.1 * e * std::complex<double>(0.2, 1.2)); //std::list<double>::const_iterator ei = e.begin(); //std::list<std::complex<double> >::const_iterator fi = f.begin(); //for (i = 0; i < n; ++i) //{ // std::cout // << "a(" << i << ") = " << a[i] // << "b(" << i << ") = " << b[i] // << "c(" << i << ") = " << c[i] // << "d(" << i << ") = " << d[i] // << "e(" << i << ") = " << *ei++ // << "f(" << i << ") = " << *fi++ // << std::endl; //} //boost::array<double,10> sad; } //]

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[regex] problem with linking to boost_regex
by Phani Deepak Parasuramuni 10 May '09

10 May '09

hi, this is the first time iam using boost::regex. when i compile the program, it lists a lot of 'undefined reference to' s to regex functions. tried setting linked flag -llibboost_regex-gcc43-mt and -L/usr/local/lib in eclipse but no use. please help. - Phani.

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building asio tutorial examples
by Paul Sutcliffe 10 May '09

10 May '09

I'm trying to build the asio tutorial code http://www.boost.org/doc/libs/1_38_0/doc/html/boost_asio/tutorial.html Is there a make file anywhere or perhaps a command line example showing exactly what libs are needed? thanks

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boost 1.38 test suite in separate files
by Nu Ai Tang 10 May '09

10 May '09

In the documentation from boost 1.38 (in the Unit Test Framework), there is this example if having multiple test suits. (Example follows..) My question is how can this be broken up and placed into different files? For example, the files could be testSuite1.cpp, testSuite2.cpp, and runTheseTestSuite.cpp. #define BOOST_TEST_MODULE example #include <boost/test/included/unit_test.hpp> BOOST_AUTO_TEST_SUITE( test_suite1 ) BOOST_AUTO_TEST_CASE( test_case1 ) { BOOST_WARN( sizeof(int) < 4 ); } BOOST_AUTO_TEST_CASE( test_case2 ) { BOOST_REQUIRE_EQUAL( 1, 2 ); BOOST_FAIL( "Should never reach this line" ); } BOOST_AUTO_TEST_SUITE_END() BOOST_AUTO_TEST_SUITE( test_suite2 ) BOOST_AUTO_TEST_CASE( test_case3 ) { BOOST_CHECK( true ); } BOOST_AUTO_TEST_CASE( test_case4 ) { BOOST_CHECK( false ); } BOOST_AUTO_TEST_SUITE_END()

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[uBLAS] Initialize a matrix by T*?
by Marco Guazzone 10 May '09

10 May '09

Hi, I'm new to uBLAS. I wonder if there is an efficient way to initialize a ublas::matrix<T> by a T*. Somthing like a copy(matrix<T>& m, T* p, size_t nrows, size_t ncols). For instance: --- [code_snip] --- double* pd = new double[10*20]; //... ublas::matrix<double> m; copy(m, pd, 10, 20); --- [/code_snip] --- Obviously I can create a 10x20 empty matrix (matrix<T> m(10,20)) and then scan the T* assigning each element one at time. But is there a more efficient way? Thank you very much in advance!! -- Marco

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boost::asio and boost::statecharts newbie question
by Dave Mazzoni 10 May '09

10 May '09

Hello all - I am using the boost::asio library to do serial I/O with simple Linux serial port(s) like /dev/ttyS0. I have found out how this works, and it is a very impressive library (I will offer a small example program so that you might include it for other users of ASIO serial ports once I've got it cleaned up). However, in addition to using boost::asio, I am using the boost::statechart library as the controller (FSM) for a project. I have managed to get the serial port working with the boost::asio library. Now, my problem is that I have an io_service defined and initialized in my statechart FSM. Is there some way to cast or otherwise use the io_service that I have therein into a serial_port? In other words, I would rather not have to put the serial port handling code in the FSM (I'd rather 'refer' to it using the io_service if it is possible). Thanks for your help! Dave

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boost::thread build with 64-bit mingw gcc
by Serge Skorokhodov 09 May '09

09 May '09

Hi, I tried to build boost 1.39 with 64-bit gcc 4.4 from www.equation.com and the thread library failed to compile. As it is stated here (http://sourceforge.net/forum/message.php?msg_id=5570690) the problem is (partly at least) lack of boost::thread support for 64-bit windows gcc. Will coming 1.40 version address this problem? TIA -- The fish that is singing in Ucayali river...

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mpl::find_if / placeholder question
by vasyl_y 09 May '09

09 May '09

Hi, I started learn mpl and here we go... I have an mpl::vector of compund types and i want to find an element in vector based on property of compound type and cannot find the way to do it, any suggestions? Here is an example how i'm trying to do it: #include <boost/mpl/vector.hpp> #include <boost/mpl/find_if.hpp> #include <boost/type_traits.hpp> namespace mpl = boost::mpl; template<typename T, int id> struct Type2IdLink { typedef T value_type; typedef mpl::int_<id> type_id; }; typedef Type2IdLink<char, 1> v1; typedef Type2IdLink<int, 2> v2; typedef Type2IdLink<unsigned, 3> v3; typedef mpl::vector<v1, v2, v3> types; // This work typedef mpl::find_if<types, boost::is_same<mpl::_1, v2> >::type iter; // This does not work: // value_type is not a member of mpl_::_1 typedef mpl::find_if<types, boost::is_same<mpl::_1::value_type, v2> >::type iter; BOOST_MPL_ASSERT_RELATION( iter::pos::value, == , 1); Using BOOST version 1.38, GCC4.3. Thank You -- View this message in context: http://www.nabble.com/mpl%3A%3Afind_if---placeholder-question-tp23463044p23… Sent from the Boost - Users mailing list archive at Nabble.com.

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boost - asio - advise
by Tim Pynegar 09 May '09

09 May '09

Hi, I'm trying to use asio for a udp client / server arrangment. I started by calling run on the io_service object on a separate thread and the using the async_read_from and the async_send_to. I was calling these from the main application thread. I was getting a lot of these errors that was causing an exception on the io_service run method. First-chance exception at 0x7c812afb in Testbed.exe: Microsoft C++ exception: boost::system::system_error at memory location 0x0012e29c. An invalid argument was supplied This happens after calling the async_send_to method. I've added in a send buffer and started to poll the io_service object instead of running it on it's own thread which has cut down the freqency this is happening however on occations it still does and i'd like to have it running on it's own thread. The question is really should i put in a mutex lock in my sendto function that call's the async_send_to that is unlocked when i recieve the handlesentto callback that's called when the async_send_to is finished. If i do this doesn't this basically make it a blocking function call in the same way as if i call the regular send_to function. There are other options i've thought of but they all seem to result in it basically becoming blocking. I've looked through the examples and there is a lot of different potential choices to make and was looking to see if anyone could advise on an arrangement that would allow for using multiple threads but block as little as possible. Thanks, Tim.

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Asio in Windows/Linux
by Kenny Stone 09 May '09

09 May '09

I'm trying to use asio in linux and windows, and I have to use a very specific way of starting my IO Service to get it to work in windows xp: void start() { tcp::endpoint endpoint = *iterator_; socket_.async_connect(endpoint, boost::bind(&MessageHandler::handle_connect, this, boost::asio::placeholders::error, ++iterator_ ) ); boost::thread t( boost::bind( &boost::asio::io_service::run, &(socket_.get_io_service() ))); t.detach(); //threadPool_.schedule(boost::bind( &boost::asio::io_service::run, &(socket_.get_io_service()) ) ); } The commented out line is what I wanted to use (threadpool), as thread detach is far from an ideal situation. To work in windows, I have to call io_service.run() in this function and thread detach; it doesn't seem to work any other way. Everything pretty much works in linux. Is there a pattern that I should be using here for cross platform usage of the library? Any ideas why the threadpool solution doesn't work in windows? ( http://threadpool.sourceforge.net/) Thanks, -- Kenny Stone Connamara Systems, LLC

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