abir basak wrote:
Hi, I am facing some more range problem from boost::range; According to the CVS RC_1_34 works. Revision 1.21 version specified by Thorsten Ottosen , most of the classes work. What is my interest is to have a get_range function inside some of the container class like std::vector and boost::circular_buffer (from boost CVS) Here I have test class to show the problem I am facing. First, when I inherit from a vector , and specify a range function just like iterator functions ( begin() and end() )
template<typename T> class range_vector : public std::vector<T>{ public: typedef boost::sub_range<range_vector> range; typedef boost::sub_range<const range_vector> const_range; range get_range(size_type from,size_type to){ std::cout<<"range"<<std::endl; return range(begin()+from,begin()+to); } const_range get_range(size_type from,size_type to)const{ std::cout<<"const range"<<std::endl; return const_range(begin()+from,begin()+to); } }; int main(){ range_vector<int> v; int x[] = {0,1,2,3,4,5,6,7,8}; v.insert(v.end(),x,x+9); std::copy(v.begin(),v.end(),std::ostream_iterator<int>(std::cout," ")); std::cout<<std::endl; range_vector<int>::range r = v.get_range(1,5); r[0] = 100; copy(r.begin(),r.end(),std::ostream_iterator<int>(std::cout," ")); std::cout<<std::endl; range_vector<int>::const_range cr = v.get_range(1,5); copy(cr.begin(),cr.end(),std::ostream_iterator<int>(std::cout," ")); std::cout<<std::endl; const range_vector<int>& cv = v; range_vector<int>::const_range cr1 = cv.get_range(1,5); copy(cr.begin(),cr.end(),std::ostream_iterator<int>(std::cout," ")); std::cout<<std::endl; } This code compiles perfectly and gives result as expected. It also works with deque .
However when I compile the same code for boost::circular_buffer,i.e template<typename T> class range_vector : public boost::circular_buffer<T>{ public: typedef boost::sub_range<range_vector> range; typedef boost::sub_range<const range_vector> const_range; range get_range(size_type from,size_type to){ std::cout<<"range"<<std::endl; return range(begin()+from,begin()+to); } const_range get_range(size_type from,size_type to)const{ std::cout<<"const range"<<std::endl; return const_range(begin()+from,begin()+to); } }; It has a same interface that of a vector, it fails to compile when I call the non-const get_range function. i.e //Initialized the circular_buffer with a few elements. range_vector<int> v; int x[] = {0,1,2,3,4,5,6,7,8}; v.insert(v.end(),x,x+9); std::copy(v.begin(),v.end(),std::ostream_iterator<int>(std::cout," ")); std::cout<<std::endl;
///got a const reference and invoking const version of get_range. works fine. const range_vector<int>& cv = v; range_vector<int>::const_range cr1 = cv.get_range(1,5); copy(cr1.begin(),cr1.end(),std::ostream_iterator<int>(std::cout," ")); std::cout<<std::endl; ///now trying to get a non-const version range_vector<int>::range r = v.get_range(1,5); Here it gives error in Visual Studio e:\boost_1_33_1\boost\range\iterator_range.hpp(60): error C2440: 'type cast' : cannot convert from 'boost::range_iterator<C>::type' to 'boost::range_iterator<C>::type' with [ C=const boost::sub_range<range_vector<int>> ] and [ C=range_vector<int> ]
///now trying to get a non-version and assign it to const version range_vector<int>::const_range r = v.get_range(1,5); It gives the same error. Here C (container) is passed as correct one. begin() and end() are too executes correct version (non-const one). Not getting why it won't work.
Any kind of help is highly appreciated. Thanks to boost community in advance.
abir basak To make the problem little clearer, typedef boost::circular_buffer<int> cbi; typedef std::vector<int> vi; This code works, boost::sub_range<vi> get_range(vi& v,int from,int to){ return boost::sub_range<vi>(v.begin()+from,v.begin()+to); } But this don't. boost::sub_range<cbi> get_range(cbi& v,int from,int to){ return boost::sub_range<cbi>(v.begin()+from,v.begin()+to); }
-- Abir Basak, Member IEEE Software Engineer, Read Ink Technologies B. Tech, IIT Kharagpur email: abir@abirbasak.com homepage: www.abirbasak.com