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index_iterator.h

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#ifndef __INDEX_ITERATOR_H__
#define __INDEX_ITERATOR_H__


#include <iterator>
#include <functional>
#include "../src/scale.h"

namespace Generic {


template <class C, class TransformFnType=Scale::Identity<typename C::value_type> >
class index_iterator {
  typedef index_iterator self;
  typedef C Container;
  
  typedef typename Container::iterator        iterator;
  typedef typename Container::const_iterator  const_iterator;
  typedef typename Container::size_type       size_type;

public:
  typedef std::input_iterator_tag             iterator_category;
  typedef typename Container::value_type      value_type;
  typedef typename Container::difference_type difference_type;
  typedef typename Container::value_type*     pointer;
  typedef typename Container::value_type      reference;
  
  index_iterator(const const_iterator& i_, TransformFnType fn_=TransformFnType())
    : i(i_), c(0), fn(fn_) {}

  bool       operator==(const self& o) {  return (o.i == i);       }
  bool       operator!=(const self& o) {  return (o.i != i);       }
  self&      operator++ ()             {  ++i; ++c;  return *this; }
  self&      operator++ (int)          {  i++; c++;  return *this; }
  //pointer  operator-> ()             {  return &c; } // Not meaningful for an index
  reference  operator*  ()             {  return fn(c);  }
  
  const value_type& value() const { return *i;  }
  
private:
  const_iterator i;
  size_type c;

  TransformFnType fn;
};



} /* namespace Generic */
#endif /* __INDEX_ITERATOR_H__ */

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