[boost] [fusion] flatten/flatten_view Proposal

Hi there, I've created the ticket, doc&test included https://svn.boost.org/trac/boost/ticket/9294 'flatten' is an algorithm which returns a view that allows you to go through the leaf elems sequentially. For example: flatten(make_vector(1, make_vector(2, 3))) == make_vector(1, 2, 3) This is developed when I use Fusion to work with SQL for simple data mapping. In addition to 'flatten', 'support/ref' is also provided in this patch for working with mutable sequence, which I had talked with Joel sometime ago. BTW, I think the ticket below is OK to close (the patch seem applied): https://svn.boost.org/trac/boost/ticket/8270 Thanks,