ceph/src/boost/libs/numeric/odeint/include/boost/numeric/odeint/util/split_adaptor.hpp

   1 /*
   2  [auto_generated]
   3  boost/numeric/odeint/util/split_adaptor.hpp
   4
   5  [begin_description]
   6  A range adaptor which returns even-sized slices.
   7  [end_description]
   8
   9  Copyright 2013 Karsten Ahnert
  10  Copyright 2013 Mario Mulansky
  11  Copyright 2013 Pascal Germroth
  12
  13  Distributed under the Boost Software License, Version 1.0.
  14  (See accompanying file LICENSE_1_0.txt or
  15  copy at http://www.boost.org/LICENSE_1_0.txt)
  16  */
  17
  18
  19 #ifndef BOOST_NUMERIC_ODEINT_UTIL_SPLIT_ADAPTOR_INCLUDED
  20 #define BOOST_NUMERIC_ODEINT_UTIL_SPLIT_ADAPTOR_INCLUDED
  21
  22 #include <boost/range/adaptor/argument_fwd.hpp>
  23 #include <boost/range/size_type.hpp>
  24 #include <boost/range/iterator_range.hpp>
  25 #include <algorithm>
  26
  27 namespace boost {
  28 namespace numeric {
  29 namespace odeint {
  30 namespace detail {
  31
  32 /** \brief Returns the begin and end offset for a sub-range */
  33 inline std::pair<std::size_t, std::size_t>
  34 split_offsets( std::size_t total_length, std::size_t index, std::size_t parts )
  35 {
  36     BOOST_ASSERT( parts > 0 );
  37     BOOST_ASSERT( index < parts );
  38     const std::size_t
  39         slice = total_length / parts,
  40         partial = total_length % parts,
  41         lo = (std::min)(index, partial),
  42         hi = (std::max<std::ptrdiff_t>)(0, index - partial),
  43         begin_offset = lo * (slice + 1) + hi * slice,
  44         length = slice + (index < partial ? 1 : 0),
  45         end_offset = begin_offset + length;
  46     return std::make_pair( begin_offset, end_offset );
  47 }
  48
  49 /** \brief Return the sub-range `index` from a range which is split into `parts`.
  50  *
  51  * For example, splitting a range into three about equal-sized sub-ranges:
  52  * \code
  53  * sub0 = make_split_range(rng, 0, 3);
  54  * sub1 = rng | split(1, 3);
  55  * sub2 = rng | split(2, 3);
  56  * \endcode
  57  */
  58 template< class RandomAccessRange >
  59 inline iterator_range< typename range_iterator<RandomAccessRange>::type >
  60 make_split_range( RandomAccessRange& rng, std::size_t index, std::size_t parts )
  61 {
  62     const std::pair<std::size_t, std::size_t> off = split_offsets(boost::size(rng), index, parts);
  63     return make_iterator_range( boost::begin(rng) + off.first, boost::begin(rng) + off.second );
  64 }
  65
  66 template< class RandomAccessRange >
  67 inline iterator_range< typename range_iterator<const RandomAccessRange>::type >
  68 make_split_range( const RandomAccessRange& rng, std::size_t index, std::size_t parts )
  69 {
  70     const std::pair<std::size_t, std::size_t> off = split_offsets(boost::size(rng), index, parts);
  71     return make_iterator_range( boost::begin(rng) + off.first, boost::begin(rng) + off.second );
  72 }
  73
  74
  75 struct split
  76 {
  77     split(std::size_t index, std::size_t parts)
  78         : index(index), parts(parts) {}
  79     std::size_t index, parts;
  80 };
  81
  82 template< class RandomAccessRange >
  83 inline iterator_range< typename range_iterator<RandomAccessRange>::type >
  84 operator|( RandomAccessRange& rng, const split& f )
  85 {
  86     return make_split_range( rng, f.index, f.parts );
  87 }
  88
  89 template< class RandomAccessRange >
  90 inline iterator_range< typename range_iterator<const RandomAccessRange>::type >
  91 operator|( const RandomAccessRange& rng, const split& f )
  92 {
  93     return make_split_range( rng, f.index, f.parts );
  94 }
  95
  96
  97 }
  98 }
  99 }
 100 }
 101
 102 #endif