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//----------------------------------------------------------------------------
/// @file merge_four.hpp
/// @brief This file have the functions for to merge 4 buffers
///
/// @author Copyright (c) 2016 Francisco José Tapia (fjtapia@gmail.com )\n
/// Distributed under the Boost Software License, Version 1.0.\n
/// ( See accompanying file LICENSE_1_0.txt or copy at
/// http://www.boost.org/LICENSE_1_0.txt )
/// @version 0.1
///
/// @remarks
//-----------------------------------------------------------------------------
#ifndef __BOOST_SORT_PARALLEL_DETAIL_UTIL_MERGE_FOUR_HPP
#define __BOOST_SORT_PARALLEL_DETAIL_UTIL_MERGE_FOUR_HPP
#include <boost/sort/common/util/traits.hpp>
#include <boost/sort/common/range.hpp>
#include <functional>
#include <iterator>
#include <memory>
#include <vector>
namespace boost
{
namespace sort
{
namespace common
{
//
//############################################################################
// ##
// F U S I O N O F ##
// ##
// F O U R E L E M E N T S R A N G E ##
// ##
//############################################################################
//
//-----------------------------------------------------------------------------
// function : less_range
/// @brief Compare the elements pointed by it1 and it2, and if they
/// are equals, compare their position, doing a stable comparison
///
/// @param it1 : iterator to the first element
/// @param pos1 : position of the object pointed by it1
/// @param it2 : iterator to the second element
/// @param pos2 : position of the element pointed by it2
/// @param comp : comparison object
/// @return result of the comparison
//-----------------------------------------------------------------------------
template<class Iter_t, class Compare = typename util::compare_iter<Iter_t> >
inline bool less_range(Iter_t it1, uint32_t pos1, Iter_t it2, uint32_t pos2,
Compare comp = Compare())
{
return (comp(*it1, *it2)) ? true :
(pos2 < pos1) ? false : not (comp(*it2, *it1));
};
//-----------------------------------------------------------------------------
// function : full_merge4
/// @brief Merge four ranges
///
/// @param dest: range where move the elements merged. Their size must be
/// greater or equal than the sum of the sizes of the ranges
/// in vrange_input
/// @param vrange_input : array of ranges to merge
/// @param nrange_input : number of ranges in vrange_input
/// @param comp : comparison object
/// @return range with all the elements moved with the size adjusted
//-----------------------------------------------------------------------------
template<class Iter1_t, class Iter2_t, class Compare>
range<Iter1_t> full_merge4(const range<Iter1_t> &rdest,
range<Iter2_t> vrange_input[4],
uint32_t nrange_input, Compare comp)
{
typedef range<Iter1_t> range1_t;
typedef util::value_iter<Iter1_t> type1;
typedef util::value_iter<Iter2_t> type2;
static_assert (std::is_same< type1, type2 >::value,
"Incompatible iterators\n");
size_t ndest = 0;
uint32_t i = 0;
while (i < nrange_input)
{
if (vrange_input[i].size() != 0)
{
ndest += vrange_input[i++].size();
}
else
{
for (uint32_t k = i + 1; k < nrange_input; ++k)
{
vrange_input[k - 1] = vrange_input[k];
};
--nrange_input;
};
};
if (nrange_input == 0) return range1_t(rdest.first, rdest.first);
if (nrange_input == 1) return move_forward(rdest, vrange_input[0]);
if (nrange_input == 2)
{
return merge(rdest, vrange_input[0], vrange_input[1], comp);
};
//------------------------------------------------------------------------
// Initial sort
//------------------------------------------------------------------------
uint32_t pos[4] =
{ 0, 1, 2, 3 }, npos = nrange_input;
//-----------------------------------------------------------------------
// thanks to Steven Ross by their suggestion about the optimal
// sorting networks
//-----------------------------------------------------------------------
if (less_range(vrange_input[pos[1]].first, pos[1],
vrange_input[pos[0]].first, pos[0], comp))
{
std::swap(pos[0], pos[1]);
};
if (npos == 4 and less_range(vrange_input[pos[3]].first, pos[3],
vrange_input[pos[2]].first, pos[2], comp))
{
std::swap(pos[3], pos[2]);
};
if (less_range (vrange_input[pos[2]].first, pos[2],
vrange_input[pos[0]].first, pos[0], comp))
{
std::swap(pos[0], pos[2]);
};
if (npos == 4
and less_range (vrange_input[pos[3]].first, pos[3],
vrange_input[pos[1]].first, pos[1], comp))
{
std::swap(pos[1], pos[3]);
};
if (less_range (vrange_input[pos[2]].first, pos[2],
vrange_input[pos[1]].first, pos[1], comp))
{
std::swap(pos[1], pos[2]);
};
Iter1_t it_dest = rdest.first;
while (npos > 2)
{
*(it_dest++) = std::move(*(vrange_input[pos[0]].first++));
if (vrange_input[pos[0]].size() == 0)
{
pos[0] = pos[1];
pos[1] = pos[2];
pos[2] = pos[3];
--npos;
}
else
{
if (less_range(vrange_input[pos[1]].first, pos[1],
vrange_input[pos[0]].first, pos[0], comp))
{
std::swap(pos[0], pos[1]);
if (less_range(vrange_input[pos[2]].first, pos[2],
vrange_input[pos[1]].first, pos[1], comp))
{
std::swap(pos[1], pos[2]);
if (npos == 4
and less_range(vrange_input[pos[3]].first,
pos[3],
vrange_input[pos[2]].first,
pos[2], comp))
{
std::swap(pos[2], pos[3]);
};
};
};
};
};
range1_t raux1(rdest.first, it_dest), raux2(it_dest, rdest.last);
if (pos[0] < pos[1])
{
return concat(raux1,merge(raux2, vrange_input[pos[0]],
vrange_input[pos[1]], comp));
}
else
{
return concat(raux1, merge (raux2, vrange_input[pos[1]],
vrange_input[pos[0]], comp));
};
};
//-----------------------------------------------------------------------------
// function : uninit_full_merge4
/// @brief Merge four ranges and put the result in uninitialized memory
///
/// @param dest: range where create and move the elements merged. Their
/// size must be greater or equal than the sum of the sizes
/// of the ranges in the array R
/// @param vrange_input : array of ranges to merge
/// @param nrange_input : number of ranges in vrange_input
/// @param comp : comparison object
/// @return range with all the elements move with the size adjusted
//-----------------------------------------------------------------------------
template<class Value_t, class Iter_t, class Compare>
range<Value_t *> uninit_full_merge4(const range<Value_t *> &dest,
range<Iter_t> vrange_input[4],
uint32_t nrange_input, Compare comp)
{
typedef util::value_iter<Iter_t> type1;
static_assert (std::is_same< type1, Value_t >::value,
"Incompatible iterators\n");
size_t ndest = 0;
uint32_t i = 0;
while (i < nrange_input)
{
if (vrange_input[i].size() != 0)
{
ndest += vrange_input[i++].size();
}
else
{
for (uint32_t k = i + 1; k < nrange_input; ++k)
{
vrange_input[k - 1] = vrange_input[k];
};
--nrange_input;
};
};
if (nrange_input == 0) return range<Value_t *>(dest.first, dest.first);
if (nrange_input == 1) return move_construct(dest, vrange_input[0]);
if (nrange_input == 2)
{
return merge_construct(dest, vrange_input[0], vrange_input[1], comp);
};
//------------------------------------------------------------------------
// Initial sort
//------------------------------------------------------------------------
uint32_t pos[4] = { 0, 1, 2, 3 }, npos = nrange_input;
//-----------------------------------------------------------------------
// thanks to Steven Ross by their suggestion about the optimal
// sorting networks
//-----------------------------------------------------------------------
if (less_range(vrange_input[pos[1]].first, pos[1],
vrange_input[pos[0]].first, pos[0], comp))
{
std::swap(pos[0], pos[1]);
};
if (npos == 4 and less_range(vrange_input[pos[3]].first, pos[3],
vrange_input[pos[2]].first, pos[2], comp))
{
std::swap(pos[3], pos[2]);
};
if (less_range(vrange_input[pos[2]].first, pos[2],
vrange_input[pos[0]].first, pos[0], comp))
{
std::swap(pos[0], pos[2]);
};
if (npos == 4 and less_range(vrange_input[pos[3]].first, pos[3],
vrange_input[pos[1]].first, pos[1], comp))
{
std::swap(pos[1], pos[3]);
};
if (less_range(vrange_input[pos[2]].first, pos[2],
vrange_input[pos[1]].first, pos[1], comp))
{
std::swap(pos[1], pos[2]);
};
Value_t *it_dest = dest.first;
while (npos > 2)
{
util::construct_object(&(*(it_dest++)),
std::move(*(vrange_input[pos[0]].first++)));
if (vrange_input[pos[0]].size() == 0)
{
pos[0] = pos[1];
pos[1] = pos[2];
pos[2] = pos[3];
--npos;
}
else
{
if (less_range (vrange_input[pos[1]].first, pos[1],
vrange_input[pos[0]].first, pos[0], comp))
{
std::swap(pos[0], pos[1]);
if (less_range (vrange_input[pos[2]].first, pos[2],
vrange_input[pos[1]].first, pos[1], comp))
{
std::swap(pos[1], pos[2]);
if (npos == 4 and less_range(vrange_input[pos[3]].first,
pos[3],
vrange_input[pos[2]].first,
pos[2], comp))
{
std::swap(pos[2], pos[3]);
};
};
};
};
}; // end while (npos > 2)
range<Value_t *> raux1(dest.first, it_dest), raux2(it_dest, dest.last);
if (pos[0] < pos[1])
{
return concat(raux1,
merge_construct(raux2, vrange_input[pos[0]],
vrange_input[pos[1]], comp));
}
else
{
return concat(raux1,
merge_construct(raux2, vrange_input[pos[1]],
vrange_input[pos[0]], comp));
};
};
//****************************************************************************
};// End namespace common
};// End namespace sort
};// End namespace boost
//****************************************************************************
//
#endif
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