Method 3.1: Implement a Range Adaptor without arguments

To implement a Range Adaptor without arguments (e.g. reversed) you need to:

Provide a range for your return type, for example:

#include <boost/range/iterator_range.hpp>
#include <boost/iterator/reverse_iterator.hpp>

template< typename R >
struct reverse_range :
    boost::iterator_range<
        boost::reverse_iterator<
            typename boost::range_iterator<R>::type> >
{
private:
    typedef boost::iterator_range<
        boost::reverse_iterator<
            typename boost::range_iterator<R>::type> > base;

public:
    typedef boost::reverse_iterator<
        typename boost::range_iterator<R>::type > iterator;

    reverse_range(R& r)
        : base(iterator(boost::end(r)), iterator(boost::begin(r)))
    { }
};

Provide a tag to uniquely identify your adaptor in the operator| function overload set
```
namespace detail {
    struct reverse_forwarder {};
}
```

Implement operator|

template< class BidirectionalRng >
inline reverse_range<BidirectionalRng>
operator|( BidirectionalRng& r, detail::reverse_forwarder )
{
	return reverse_range<BidirectionalRng>( r );
}

template< class BidirectionalRng >
inline reverse_range<const BidirectionalRng>
operator|( const BidirectionalRng& r, detail::reverse_forwarder )
{
	return reverse_range<const BidirectionalRng>( r );
}

Declare the adaptor itself (it is a variable of the tag type).

namespace
{
    const detail::reverse_forwarder reversed = detail::reverse_forwarder();
}