Re: [boost] stride_iterator_policy

From: Jeremy Siek (jsiek_at_[hidden])
Date: 2001-08-27 09:06:06

Sounds good! :) I assume you'll add all the other iterator operations such
as decrement, advance, etc.

Cheers,
Jeremy

On Mon, 27 Aug 2001, Toon Knapen wrote:

toon> If others would also be interested I would like to see iterator_adaptors
toon> extended with a strided_iterator_policy.
toon>
toon> Using the strided_iterator_policy, every increment of the iterator will
toon> advance the iterator according a user defined 'stride'
toon>
toon> { // begin example :
toon>
toon>    template < int N >
toon>    class stride_iterator_policy : public boost::default_iterator_policies
toon>    {
toon>    public:
toon>      template <class BaseType>
toon>      static void increment(BaseType& x) { std::advance( x, N ); }
toon>    };
toon>
toon> boost::iterator_adaptor< RealValues::const_iterator,
toon>    stride_iterator_policy<3> > dof_it( dof_values.begin() );
toon> prod = std::inner_product( shapes.begin(), shapes.end(), dof_it, 0.0 );
toon>
toon> } // end example
toon>
toon> The iterator is here used to traverse the first row of every column in a
toon> column-major matrix.
toon>
toon>
toon>
toon> This type of iterator is frequently used within for instance matrix
toon> operations.
toon>
toon> toon
toon>
toon>
toon> Info: http://www.boost.org  Unsubscribe: <mailto:boost-unsubscribe_at_[hidden]>
toon>
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toon>
toon>
toon>

----------------------------------------------------------------------
 Jeremy Siek                          http://php.indiana.edu/~jsiek/
 Ph.D. Student, Indiana Univ. B'ton   email: jsiek_at_[hidden]
 C++ Booster (http://www.boost.org)   office phone: [phone]
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