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