Re: Boost algorithm library (Was: [boost] New upload: algorithm.zip 1)

From: helmut.zeisel_at_[hidden]
Date: 2001-07-26 01:47:51

--- In boost_at_y..., helmut.zeisel_at_a... wrote:
> --- In boost_at_y..., "Vesa Karvonen" <vesa.karvonen_at_h...> wrote:
> > From: "Fernando Cacciola" <fcacciola_at_g...>

> > 
> > As related issue, it is possible to write functions that return an
> object that
> > has a container-like interface (has begin() and end()), but refers
> to the
> > elements of the container differently. 
> 

To make that idea clearer,
I include a complete tested (VC++6) code example
("copy" is a completely rewritten code,
"sort", for simplicity, just wraps std::sort)

Helmut

template<typename Iterator> struct range
{
   Iterator m_begin;
   Iterator m_end;
   range(Iterator begin, Iterator end): m_begin(begin), m_end(end) {}
   Iterator begin() const {return m_begin;}
   Iterator end() const {return m_end;}
   typedef Iterator iterator;
};

template<typename Iterator> range<Iterator>
make_range(Iterator begin, Iterator end)
{
  return range<Iterator>(begin,end);
}

template<typename Range>  void sort(Range& r)
{
  std::sort(r.begin(), r.end());
}
template<typename Range, typename Out>  void copy(Range& r, Out res)
{
  typename Range::iterator it=r.begin();
  while(it != r.end())
  {
    *res++ = *it++;
  }
}

#include <algorithm>
#include <vector>
#include <iostream>
int main()
{
  std::vector<int> v;
  v.push_back(2);
  v.push_back(3);
  v.push_back(1);
  int w[]={3,2,4,1};
  static const int n = sizeof(w)/sizeof(int);
  sort(v);
  copy(v,std::ostream_iterator<int>(std::cout," "));
  std::cout << "\n";
  sort(make_range(w,w+n));
  copy(make_range(w,w+n),std::ostream_iterator<int>(std::cout," "));

  return 0;
}