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

Subject: [boost] [iterator] Is there general const_iterator adaptor?
From: TONGARI (tongari95_at_[hidden])
Date: 2013-04-28 02:50:38

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