Chris@102: /*
Chris@102:  [auto_generated]
Chris@102:  boost/numeric/odeint/util/split_adaptor.hpp
Chris@102: 
Chris@102:  [begin_description]
Chris@102:  A range adaptor which returns even-sized slices.
Chris@102:  [end_description]
Chris@102: 
Chris@102:  Copyright 2013 Karsten Ahnert
Chris@102:  Copyright 2013 Mario Mulansky
Chris@102:  Copyright 2013 Pascal Germroth
Chris@102: 
Chris@102:  Distributed under the Boost Software License, Version 1.0.
Chris@102:  (See accompanying file LICENSE_1_0.txt or
Chris@102:  copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@102:  */
Chris@102: 
Chris@102: 
Chris@102: #ifndef BOOST_NUMERIC_ODEINT_UTIL_SPLIT_ADAPTOR_INCLUDED
Chris@102: #define BOOST_NUMERIC_ODEINT_UTIL_SPLIT_ADAPTOR_INCLUDED
Chris@102: 
Chris@102: #include <boost/range/adaptor/argument_fwd.hpp>
Chris@102: #include <boost/range/size_type.hpp>
Chris@102: #include <boost/range/iterator_range.hpp>
Chris@102: #include <algorithm>
Chris@102: 
Chris@102: namespace boost {
Chris@102: namespace numeric {
Chris@102: namespace odeint {
Chris@102: namespace detail {
Chris@102: 
Chris@102: /** \brief Returns the begin and end offset for a sub-range */
Chris@102: inline std::pair<std::size_t, std::size_t>
Chris@102: split_offsets( std::size_t total_length, std::size_t index, std::size_t parts )
Chris@102: {
Chris@102:     BOOST_ASSERT( parts > 0 );
Chris@102:     BOOST_ASSERT( index < parts );
Chris@102:     const std::size_t
Chris@102:         slice = total_length / parts,
Chris@102:         partial = total_length % parts,
Chris@102:         lo = (std::min)(index, partial),
Chris@102:         hi = (std::max<std::ptrdiff_t>)(0, index - partial),
Chris@102:         begin_offset = lo * (slice + 1) + hi * slice,
Chris@102:         length = slice + (index < partial ? 1 : 0),
Chris@102:         end_offset = begin_offset + length;
Chris@102:     return std::make_pair( begin_offset, end_offset );
Chris@102: }
Chris@102: 
Chris@102: /** \brief Return the sub-range `index` from a range which is split into `parts`.
Chris@102:  *
Chris@102:  * For example, splitting a range into three about equal-sized sub-ranges:
Chris@102:  * \code
Chris@102:  * sub0 = make_split_range(rng, 0, 3);
Chris@102:  * sub1 = rng | split(1, 3);
Chris@102:  * sub2 = rng | split(2, 3);
Chris@102:  * \endcode
Chris@102:  */
Chris@102: template< class RandomAccessRange >
Chris@102: inline iterator_range< typename range_iterator<RandomAccessRange>::type >
Chris@102: make_split_range( RandomAccessRange& rng, std::size_t index, std::size_t parts )
Chris@102: {
Chris@102:     const std::pair<std::size_t, std::size_t> off = split_offsets(boost::size(rng), index, parts);
Chris@102:     return make_iterator_range( boost::begin(rng) + off.first, boost::begin(rng) + off.second );
Chris@102: }
Chris@102: 
Chris@102: template< class RandomAccessRange >
Chris@102: inline iterator_range< typename range_iterator<const RandomAccessRange>::type >
Chris@102: make_split_range( const RandomAccessRange& rng, std::size_t index, std::size_t parts )
Chris@102: {
Chris@102:     const std::pair<std::size_t, std::size_t> off = split_offsets(boost::size(rng), index, parts);
Chris@102:     return make_iterator_range( boost::begin(rng) + off.first, boost::begin(rng) + off.second );
Chris@102: }
Chris@102: 
Chris@102: 
Chris@102: struct split
Chris@102: {
Chris@102:     split(std::size_t index, std::size_t parts)
Chris@102:         : index(index), parts(parts) {}
Chris@102:     std::size_t index, parts;
Chris@102: };
Chris@102: 
Chris@102: template< class RandomAccessRange >
Chris@102: inline iterator_range< typename range_iterator<RandomAccessRange>::type >
Chris@102: operator|( RandomAccessRange& rng, const split& f )
Chris@102: {
Chris@102:     return make_split_range( rng, f.index, f.parts );
Chris@102: }
Chris@102: 
Chris@102: template< class RandomAccessRange >
Chris@102: inline iterator_range< typename range_iterator<const RandomAccessRange>::type >
Chris@102: operator|( const RandomAccessRange& rng, const split& f )
Chris@102: {
Chris@102:     return make_split_range( rng, f.index, f.parts );
Chris@102: }
Chris@102: 
Chris@102: 
Chris@102: }
Chris@102: }
Chris@102: }
Chris@102: }
Chris@102: 
Chris@102: #endif