[boost] [iterator] Is there general const_iterator adaptor?

Hi folks, I wonder if there's a general const_iterator adaptor that transforms any iterator to a const one: template<class Iterator> struct const_iterator : iterator_adaptor < const_iterator<Iterator>, Iterator , typename iterator_value<Iterator>::type const > { const_iterator() {} const_iterator(Iterator const& base) : const_iterator::iterator_adaptor_(base) {} }; Which is simple but handy for use in that we don't have to make 2 versions for both const & non-const iterators each time we make a container. Does Boost offer this which I missed somewhere, or would you think it's a good idea to add? Thanks