#include <boost/iterator/iterator_adaptor.hpp>
#include <boost/range/iterator_range.hpp>
#include <boost/iterator/filter_iterator.hpp>

#include <iterator>
#include <string>

namespace client {

    template<typename Iterator>
    class bottom_layer_iterator
        : public boost::iterator_adaptor<
        bottom_layer_iterator<Iterator>,     // Derived
        Iterator,                        // Base
        boost::use_default,              // Value
        boost::forward_traversal_tag     // CategoryOrTraversal
        >
    {
    public:
        bottom_layer_iterator()
            : bottom_layer_iterator::iterator_adaptor_()
        { }

        explicit bottom_layer_iterator( Iterator base )
            : bottom_layer_iterator::iterator_adaptor_( base )
        { }

    private:

        friend class boost::iterator_core_access;

        void increment()
        {
            ++this->base_reference();
        }
    };

    namespace detail
    {

        template <typename CharT = char>
        struct equal_to
        {
            equal_to()
                : comment_char( '|' )
            { }

            bool operator()( CharT c ) const { return c == comment_char; }
            CharT comment_char;
        };
    }


    template <typename CharT>
    struct basic_input_iterator
    {
        typedef std::basic_string<CharT>                range_type;
        typedef bottom_layer_iterator<typename range_type::const_iterator> basic_iterator_type;
        typedef boost::filter_iterator<detail::equal_to<typename basic_iterator_type::value_type>, basic_iterator_type> type;
    };

    typedef basic_input_iterator<char>::type        default_input_iterator;

}

int main()
{
    const std::string rng;

    client::default_input_iterator first( rng.begin() );
    //client::default_input_iterator last( rng.end() );
}