[Boost-users] using transform_iterator with std::lower_bound

From: Alexis H. Rivera-Rios (ahrivera_at_[hidden])
Date: 2008-02-05 00:05:04

Hi,

I'm trying to use a transform iterator and lower_bound
to search a list of integers as if it was list of
booleans.  

According to the message the const_mem_fun_ref_t
doesn't have a default constructor. Is there a way to
make this code compile?  

Your help will be appreciated!
Alex

#include<functional>
#include <vector>
#include <algorithm>
#include <boost/iterator/transform_iterator.hpp>

class T
{
public:
        int _a;
        T(int a) : _a(a) {}
        bool greaterZero() const { return _a > 0; }
};

int main(void)
{
        typedef std::vector<T> Tlist;
        typedef std::const_mem_fun_ref_t<bool,T> Function;
    typedef boost::transform_iterator<Function,
                                     
Tlist::const_iterator> Iterator;
        
        Tlist x;
        Iterator
b(x.begin(),std::mem_fun_ref<bool,T>(&T::greaterZero)),
                
e(x.end(),std::mem_fun_ref<bool,T>(&T::greaterZero));
                
   
        std::lower_bound(b,e,false);   
}

Error log:
BD Software STL Message Decryptor v3.10 for gcc 2/3/4
matob.cpp:28:2: warning: no newline at end of file
/cygdrive/c/opt/boost_1_34_1/boost/iterator/transform_iterator.hpp:
In
    constructor 
   `boost::transform_iterator<
        main()::Function, vector<T>::const_iterator,
boost::use_default
      , boost::use_default
    >::transform_iterator()':
stl_algo.h:2627:   instantiated from 
   `boost::transform_iterator<
        main()::Function, vector<T>::const_iterator,
boost::use_default
      , boost::use_default
    > lower_bound(
        boost::transform_iterator<
            main()::Function,
vector<T>::const_iterator, boost::use_default
          , boost::use_default
        >, boost::transform_iterator<
            main()::Function,
vector<T>::const_iterator, boost::use_default
          , boost::use_default
        >, const bool &
    )'
matob.cpp:26:   instantiated from here
/cygdrive/c/opt/boost_1_34_1/boost/iterator/transform_iterator.hpp:100:
error:
    No match for `const_mem_fun_ref_t<bool,
T>::const_mem_fun_ref_t()'
stl_function.h:640: candidates are:
const_mem_fun_ref_t<bool, T>
    ::const_mem_fun_ref_t(const
const_mem_fun_ref_t<bool, T> &)
stl_function.h:644:  const_mem_fun_ref_t<
        bool, T>::const_mem_fun_ref_t(bool (T::*)()
const)

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