[boost] [yield_iterator] new iterator lib with C# yield return/yield break

Subject: [boost] [yield_iterator] new iterator lib with C# yield return/yield break
From: Oliver Kowalke (oliver.kowalke_at_[hidden])
Date: 2011-06-20 14:15:08

I've uploaded a new lib 'yield_iterator' 
(http://www.boostpro.com/vault/index.php?action=downloadfile&filename=boost.yield_iterator-0.1.0.zip&directory=Iterators&). 
Documentation can be found also here: 
http://ok73.ok.funpic.de/boost/libs/yield_iterator/docu/html/ .

The lib provides the same functionality as C# does with the 'yield 
return' and 'yield break' statements - this lib provides an easy way to 
iterate complex containers. The library uses boost.context internally.

For instance iterating an tree would usally require to traverse the 
complete tree and store the nodes in a STL container - the begin/end 
iterators of this STL container are used to iterate the tree.
With boost.yield_iterator you have only to derive a class from 
yield_adapter and overload the function 'void iterate()'.
In 'void iterate()' you can iterate locally over the internal data and 
return appropriate elements via 'yield_return()'.

class  tree_adapter  :  public  boost::yield_adapter<  leaf  >,
                                        public  visitor
{
private:
        node::ptr_t      root_;

public:
        tree_adapter()  :
                boost::yield_adapter<  leaf  >(),
                root_()
        {}

        tree_adapter(  node::ptr_t  root)  :
                boost::yield_adapter<  leaf  >(  true),
                root_(  root)
        {  BOOST_ASSERT(  root_);  }

        void  visit(  branch  &  b)
        {
                if  (  b.left)  b.left->accept(  *  this);
                if  (  b.right)  b.right->accept(  *  this);
        }

        void  visit(  leaf  &  l)
        {  yield_return(  l);  }

        void  iterate()
        {  root_->accept(  *  this);  }
};

int  main(  int  argc,  char  *  argv[])
{
        {
                node::ptr_t  root  =  create_tree();
                boost::yield_iterator<  tree_adapter  >  e;
                for  (
                                boost::yield_iterator<  tree_adapter  >  i(  root);
                                i  !=  e;  ++i)  {
                        std::cout  <<  i->value  <<   "";
                }
        }

        std::cout  <<  "\nDone"  <<  std::endl;

        return  EXIT_SUCCESS;
}

The library contains a example iterating over a tree via visitor pattern 
an yield_iterator.

I hope I get some feedback.

best regards,
Oliver