Convenience function for the compose_f_gx_hx adapter

[aruljothi]

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
#include <functional>

#include <iostream>

/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
    typename T::const_iterator pos;

    std::cout << optcstr;
    for (pos=coll.begin(); pos!=coll.end(); ++pos) {
        std::cout << *pos << ' ';
    }
    std::cout << std::endl;
}





/* class for the compose_f_gx_hx adapter
*/
template <class OP1, class OP2, class OP3>
class compose_f_gx_hx_t
: public std::unary_function<typename OP2::argument_type,
                              typename OP1::result_type>
{
  private:
    OP1 op1;    // process: op1(op2(x),op3(x))
    OP2 op2;
    OP3 op3;
  public:
    // constructor
    compose_f_gx_hx_t (const OP1& o1, const OP2& o2, const OP3& o3)
     : op1(o1), op2(o2), op3(o3) {
    }

    // function call
    typename OP1::result_type
    operator()(const typename OP2::argument_type& x) const {
        return op1(op2(x),op3(x));
    }
};

/* convenience function for the compose_f_gx_hx adapter
*/
template <class OP1, class OP2, class OP3>
inline compose_f_gx_hx_t<OP1,OP2,OP3>
compose_f_gx_hx (const OP1& o1, const OP2& o2, const OP3& o3) {
    return compose_f_gx_hx_t<OP1,OP2,OP3>(o1,o2,o3);
}




int main()
{
    vector<int> coll;

    // insert elements from 1 to 9
    for (int i=1; i<=9; ++i) {
        coll.push_back(i);
    }
    PRINT_ELEMENTS(coll);

    // remove all elements that are greater than four and less than seven
    // - retain new end
    vector<int>::iterator pos;
    pos = remove_if (coll.begin(),coll.end(),
                     compose_f_gx_hx(logical_and<bool>(),
                                     bind2nd(greater<int>(),4),
                                     bind2nd(less<int>(),7)));

    // remove ''removed'' elements in coll
    coll.erase(pos,coll.end());

    PRINT_ELEMENTS(coll);
}