7.6. Exercises

7-0.	Write a test program that exercises our zip_view implementation. Try to arrange your program so that it will only compile if the tests succeed.
7-1.	Our implementation of zip_iterator uses transform to generate its nested ::type, but the one in MPL uses transform_view instead. What advantage does the MPL approach have?
7-2.	Modify zip_iterator so that its ::iterator_category reflects the least-refined concept modeled by any of its underlying iterators. Extend the iterator implementation to satisfy all potential requirements of the computed category.
7-3.	Use mpl::joint_view to implement a rotate_view sequence view, presenting a shifted and wrapped view onto the original sequence: typedef mpl::vector_c<int,5,6,7,8,9,0,1,2,3,4> v; typedef rotate_view< v , mpl::advance_c<mpl::begin<v>::type,5>::type > view; BOOST_STATIC_ASSERT(( mpl::equal< view , mpl::range_c<int,0,10> >::value ));
7-4.	Design and implement an iterator adaptor that adapts any Random Access Iterator by presenting the elements it traverses in an order determined by a sequence of nonnegative integer indices. Make your permutation_iterator a forward iterator.
7-5.	Change the permutation iterator from exercise 7-4 so its traversal category is determined by the category of the sequence of indices.
7-6.	Implement a permutation_view using your permutation iterator adaptor, so that: permutation_view< mpl::list_c<int,2,1,3,0,2> // indices , mpl::vector_c<int,11,22,33,44> // elements > yields sequence [33,22,44,11,33]
7-7.	Design and implement a reverse iterator adaptor with semantics analogous to those of std::reverse_iterator. Make its category the same as the category of the underlying iterator. Use the resulting iterator to implement a reverse_view template.
7-8.	Implement a crossproduct_view template that adapts two original sequences by presenting all possible pairs of their elements in a right cross product order.